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Sample records for crystal forehead temperature

  1. A comparative study on accuracy of liquid crystal forehead, digital electronic axillary, infrared tympanic with glass-mercury rectal thermometer in infants and young children.

    Science.gov (United States)

    Kongpanichkul, A; Bunjongpak, S

    2000-09-01

    This study was carried out to assess the accuracy of three devices namely, liquid crystal forehead, digital electronic axillary and infrared tympanic thermometer, using a glass-mercury rectal thermometer as the control. The subjects were two hundred children aged 0-48 months. The mean rectal temperature was 38.0 +/- 0.91 degrees C; forehead, 37.83 +/- 0.94 degrees C; tympanic, 37.77 +/- 0.95 degrees C, and axillary, 37.71 +/- 0.86 degrees C. Compared to the rectal temperature, all values were significantly lower (p < 0.05). Forehead, tympanic and axillary temperature differed from rectal temperature by at least 0.5 degrees C in 33.33 per cent, 23.5 per cent and 31.5 per cent of subjects, and at least 1 degrees C in 22 per cent, 1 per cent and 6 per cent of subjects respectively. Accuracy in detection of fever was 79 per cent for forehead, 85.5 per cent for tympanic and 84 per cent for axillary thermometry. Sensitivity of the three devices was 67-83 per cent in detection of fever and 64-77 per cent in detection of high fever. Tympanic thermometry had the best performance while forehead thermometry had the poorest. After using revised diagnostic threshold temperature by ROC curves, sensitivity of each device improved but accuracy was nearly the same. It is concluded that the three devices are not suitable as a substitute for a glass-mercury rectal thermometer in assessment of fever in infants and young children.

  2. Reliability of an infrared forehead skin thermometer for core temperature measurements

    NARCIS (Netherlands)

    Kistemaker, J.A.; Hartog, E.A. den; Daanen, H.A.M.

    2006-01-01

    The SensorTouch thermometer performs an infrared measurement of the skin temperature above the Superficial Temporal Artery (STA). This study evaluates the validity and the accuracy of the SensorTouch thermometer. Two experiments were performed in which the body temperature was measured with a rectal

  3. Reconstruction of the forehead acoustic properties in an Indo-Pacific humpback dolphin (Sousa chinensis), with investigation on the responses of soft tissue sound velocity to temperature.

    Science.gov (United States)

    Song, Zhongchang; Zhang, Yu; Berggren, Per; Wei, Chong

    2017-02-01

    Computed tomography (CT) imaging and ultrasound experimental measurements were combined to reconstruct the acoustic properties (density, velocity, and impedance) of the head from a deceased Indo-Pacific humpback dolphin (Sousa chinensis). The authors extracted 42 soft forehead tissue samples to estimate the sound velocity and density properties at room temperature, 25.0  °C. Hounsfield Units (HUs) of the samples were read from CT scans. Linear relationships between the tissues' HUs and velocity, and HUs and density were revealed through regression analyses. The distributions of the head acoustic properties at axial, coronal, and sagittal cross sections were reconstructed, suggesting that the forehead soft tissues were characterized by low-velocity in the melon, high-velocity in the muscle and connective tissues. Further, the sound velocities of melon, muscle, and connective tissue pieces were measured under different temperatures to investigate tissues' velocity response to temperature. The results demonstrated nonlinear relationships between tissues' sound velocity and temperature. This study represents a first attempt to provide general information on acoustic properties of this species. The results could provide meaningful information for understanding the species' bioacoustic characteristics and for further investigation on sound beam formation of the dolphin.

  4. Behaviour of polar crystals at low temperatures

    International Nuclear Information System (INIS)

    Drozhdin, S.N.; Novik, V.K.; Gavrilova, N.D.; Koptsik, V.A.; Popova, T.V.

    1975-01-01

    Temperature dependencies of pyrocoefficient for a wide class of various pyroactive crystals in the temperature range from 4,2 to 300 deg K were investigated. The problems to be solved were: to confirm a conclusion on the pyrocoefficient γsup(sigma) tending to zero at T → 0; to compare experimental data with conclusions of existing theories; to reveal specific features in the behaviour of both linear pyroelectrics and segnetoelectrics at low temperatures. The behaviour of the total pyrocoefficient for all crystals obeys the regularity γsup(sigma) → 0 at T → O. In the range of low temperatures the pyrocoefficient varies by the power law: γsup(sigma) approximately Tsup(α). For the majority of crystals studied α is close to 3. CdS, BeO, ZiNbO 3 and other crystals were studied

  5. Median forehead flap - beyond classic indication

    Directory of Open Access Journals (Sweden)

    Cristian R. Jecan

    2016-11-01

    Full Text Available Introduction. The paramedian forehead flap is one of the best options for reconstruction of the median upper two-thirds of the face due to its vascularity, color, texture match and ability to resurface all or part of the reconstructed area. The forehead flap is the gold standard for nasal soft tissue reconstruction and the flap of choice for larger cutaneous nasal defects having a robust pedicle and large amount of tissue. Materials and Methods. We are reporting a clinical series of cutaneous tumors involving the nose, medial canthus, upper and lower eyelid through a retrospective review of 6 patients who underwent surgical excision of the lesion and primary reconstruction using a paramedian forehead flap. Results. The forehead flap was used for total nose reconstruction, eyelids and medial canthal reconstruction. All flaps survived completely and no tumor recurrence was seen in any of the patients. Cosmetic and functional results were favorable. Conclusions. The forehead flap continues to be one of the best options for nose reconstruction and for closure of surgical defects of the nose larger than 2 cm. Even though is not a gold standard, median forehead flap can be an advantageous technique in periorbital defects reconstruction.

  6. Crystal growth from low-temperature solutions

    International Nuclear Information System (INIS)

    Sangwal, K.

    1994-01-01

    The state of the art in crystal growth from solutions at low-temperatures has been done. The thermodynamic and kinetic parameters have been discussed in respect to different systems. The methods of crystal growth from water and organic solutions and different variants of their technical realizations have been reviewed. Also the growth by chemical reactions and gel growth have been described. The large number of examples have been shown. 21 refs, 30 figs, 3 tabs

  7. Quartz Crystal Temperature Sensor for MAS NMR

    Science.gov (United States)

    Simon, Gerald

    1997-10-01

    Quartz crystal temperature sensors (QCTS) were tested for the first time as wireless thermometers in NMR MAS rotors utilizing the NMR RF technique itself for exiting and receiving electro-mechanical quartz resonances. This new tool in MAS NMR has a high sensitivity, linearity, and precision. When compared to the frequently used calibration of the variable temperature in the NMR system by a solid state NMR chemical shift thermometer (CST), such as lead nitrate, QCTS shows a number of advantages. It is an inert thermometer in close contact with solid samples operating parallel to the NMR experiment. QCTS can be manufactured for any frequency to be near a NMR frequency of interest (typically 1 to 2 MHz below or above). Due to the strong response of the crystal, signal detection is possible without changing the tuning of the MAS probe. The NMR signal is not influenced due to the relative sharp crystal resonance, restricted excitation by finite pulses, high probeQvalues, and commonly used audio filters. The quadratic dependence of the temperature increase on spinning speed is the same for the QCTS and for the CST lead nitrate and is discussed in terms of frictional heat in accordance with the literature about lead nitrate and with the results of a simple rotor speed jump experiment with differently radial located lead nitrate in the rotor.

  8. Temperature fields in a growing solar silicon crystal

    Directory of Open Access Journals (Sweden)

    Kondrik A. I.

    2012-06-01

    Full Text Available The optimal thermal terms for growing by Czochralski method Si single-crystals, suitable for making photoelectric energy converters, has been defined by the computer simulation method. Dependences of temperature fields character and crystallization front form on the diameter of the crystal, stage and speed of growing, and also on correlation between diameter and height of the crystal has been studied.

  9. Preventing Crystal Agglomeration of Pharmaceutical Crystals Using Temperature Cycling and a Novel Membrane Crystallization Procedure for Seed Crystal Generation

    Directory of Open Access Journals (Sweden)

    Elena Simone

    2018-01-01

    Full Text Available In this work, a novel membrane crystallization system was used to crystallize micro-sized seeds of piroxicam monohydrate by reverse antisolvent addition. Membrane crystallization seeds were compared with seeds produced by conventional antisolvent addition and polymorphic transformation of a fine powdered sample of piroxicam form I in water. The membrane crystallization process allowed for a consistent production of pure monohydrate crystals with narrow size distribution and without significant agglomeration. The seeds were grown in 350 g of 20:80 w/w acetone-water mixture. Different seeding loads were tested and temperature cycling was applied in order to avoid agglomeration of the growing crystals during the process. Focused beam reflectance measurement (FBRM; and particle vision and measurement (PVM were used to monitor crystal growth; nucleation and agglomeration during the seeded experiments. Furthermore; Raman spectroscopy was used to monitor solute concentration and estimate the overall yield of the process. Membrane crystallization was proved to be the most convenient and consistent method to produce seeds of highly agglomerating compounds; which can be grown via cooling crystallization and temperature cycling.

  10. Anomalously temperature-independent birefringence in biaxial optical crystals

    International Nuclear Information System (INIS)

    Grechin, Sergei G; Dmitriev, Valentin G; Dyakov, Vladimir A; Pryalkin, Vladimir I

    2000-01-01

    Temperature-independent birefringence in a biaxial crystal was predicted theoretically and observed experimentally for the first time. The width of the plot against temperature (the range corresponding to the temperature independence of the birefringence) at a fundamental radiation wavelength of 632.8 nm in a KTP crystal 5.9 mm long was more than 160 0 C. (letters to the editor)

  11. Cooling Crystallization of Indomethacin: Effect of Supersaturation, Temperature and Seeding on Polymorphism and Crystal Size Distribution

    DEFF Research Database (Denmark)

    Malwade, Chandrakant Ramkrishna; Qu, Haiyan

    2018-01-01

    In this work, effect of crystallization parameters i.e., supersaturation, seeding, and temperature on polymorphism and crystal size of a non-steroidal anti-inflammatory drug, indomethacin (IMC), was investigated. Firstly, several crystallization solvents (ethanol, methanol, ethyl acetate, acetone...... of IMC from ethanol confirmed that the supersaturation, operating temperature and seeding does affect the polymorphism as well as crystal size distribution of IMC. Fine needle shaped crystals of metastable α-IMC were obtained at 5 °C with high supersaturation even in presence of γ-IMC seeds, while...... rhombic plates like crystals of thermodynamically stable γ-IMC were obtained in remaining experiments. The amount of seed loading only marginally influenced the crystal growth rate and median particle diameter (d50). Particle size analysis of crystals obtained showed bimodal distribution in all...

  12. High-quality bulk hybrid perovskite single crystals within minutes by inverse temperature crystallization

    KAUST Repository

    Saidaminov, Makhsud I.

    2015-07-06

    Single crystals of methylammonium lead trihalide perovskites (MAPbX3; MA=CH3NH3+, X=Br− or I−) have shown remarkably low trap density and charge transport properties; however, growth of such high-quality semiconductors is a time-consuming process. Here we present a rapid crystal growth process to obtain MAPbX3 single crystals, an order of magnitude faster than previous reports. The process is based on our observation of the substantial decrease of MAPbX3 solubility, in certain solvents, at elevated temperatures. The crystals can be both size- and shape-controlled by manipulating the different crystallization parameters. Despite the rapidity of the method, the grown crystals exhibit transport properties and trap densities comparable to the highest quality MAPbX3 reported to date. The phenomenon of inverse or retrograde solubility and its correlated inverse temperature crystallization strategy present a major step forward for advancing the field on perovskite crystallization.

  13. Passive Temperature Stabilization of Silicon Photonic Devices Using Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Joanna Ptasinski

    2014-03-01

    Full Text Available In this work we explore the negative thermo-optic properties of liquid crystal claddings for passive temperature stabilization of silicon photonic integrated circuits. Photonic circuits are playing an increasing role in communications and computing, but they suffer from temperature dependent performance variation. Most existing techniques aimed at compensation of thermal effects rely on power hungry Joule heating. We show that integrating a liquid crystal cladding helps to minimize the effects of a temperature dependent drift. The advantage of liquid crystals lies in their high negative thermo-optic coefficients in addition to low absorption at the infrared wavelengths.

  14. Crystallization of Polymers Investigated by Temperature-Modulated DSC

    OpenAIRE

    Maria Cristina Righetti

    2017-01-01

    The aim of this review is to summarize studies conducted by temperature-modulated differential scanning calorimetry (TMDSC) on polymer crystallization. This technique can provide several advantages for the analysis of polymers with respect to conventional differential scanning calorimetry. Crystallizations conducted by TMDSC in different experimental conditions are analysed and discussed, in order to illustrate the type of information that can be deduced. Isothermal and non-isothermal crystal...

  15. Facial nerve activity disrupts psychomotor rhythms in the forehead microvasculature.

    Science.gov (United States)

    Drummond, Peter D; O'Brien, Geraldine

    2011-10-28

    Forehead blood flow was monitored in seven participants with a unilateral facial nerve lesion during relaxation, respiratory biofeedback and a sad documentary. Vascular waves at 0.1Hz strengthened during respiratory biofeedback, in tune with breathing cycles that also averaged 0.1Hz. In addition, a psychomotor rhythm at 0.15Hz was more prominent in vascular waveforms on the denervated than intact side of the forehead, both before and during relaxation and the sad documentary. These findings suggest that parasympathetic activity in the facial nerve interferes with the psychomotor rhythm in the forehead microvasculature. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Temperature-dependent μ-Raman investigation of struvite crystals.

    Science.gov (United States)

    Prywer, Jolanta; Kasprowicz, D; Runka, T

    2016-04-05

    The effect of temperature on the vibrational properties of struvite crystals grown from silica gels was systematically studied by μ-Raman spectroscopy. The time-dependent Raman spectra recorded in the process of long time annealing of struvite crystal at 353 K do not indicate structural changes in the struvite crystal with the time of annealing. The temperature-dependent Raman spectra recorded in the range 298-423 K reveal a phase transition in struvite at about 368 K. Above this characteristic temperature, some of bands assigned to vibrations of the PO4 and NH4 tetrahedra and water molecules observed in the Raman spectra in low temperatures (orthorhombic phase) change their spectral parameters or disappear, which indicates a transition to a higher symmetry structure of struvite in the range of high temperatures. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Temperature dependence of photonic crystals based on thermoresponsive magnetic fluids

    International Nuclear Information System (INIS)

    Pu Shengli; Bai Xuekun; Wang Lunwei

    2011-01-01

    The influence mechanisms of temperature on the band gap properties of the magnetic fluids based photonic crystals are elaborated. A method has been developed to obtain the temperature-dependent structure information (A sol /A) from the existing experimental data and then two critical parameters, i.e. the structure ratio (d/a) and the refractive index contrast (Δn) of the magnetic fluids photonic crystals are deduced for band diagram calculations. The temperature-dependent band gaps are gained for z-even and z-odd modes. Band diagram calculations display that the mid frequencies and positions of the existing forbidden bands are not very sensitive to the temperature, while the number of the forbidden bands at certain strengths of magnetic field may change with the temperature variation. The results presented in this work give a guideline for designing the potential photonic devices based on the temperature characteristics of the magnetic fluids based photonic crystals and are helpful for improving their quality. - Highlights: → Mechanisms of temperature dependence of magnetic fluids based photonic crystals are elaborated. → Properties of existing forbidden bands have relatively fine temperature stability. → Disappearance of existing forbidden band is found for some magnetic fields. → Emergence of new forbidden band with temperature is found for some magnetic fields.

  18. Temperature-mediated polymorphism in molecular crystals: The impact on crystal packing and charge transport

    KAUST Repository

    Stevens, Loah A.; Goetz, Katelyn P.; Fonari, Alexandr; Shu, Ying; Williamson, Rachel M.; Bredas, Jean-Luc; Coropceanu, Veaceslav P.; Jurchescu, Oana D.; Collis, Gavin E.

    2015-01-01

    We report a novel synthesis to ultra high purity 7,14-bis((trimethylsilyl)ethynyl)dibenzo[b,def]-chrysene (TMS-DBC) and the use of this material in the growth of single crystals by solution and vapor deposition techniques. We observe that the substrate temperature has a dramatic impact on the crystal growth, producing two distinct polymorphs of TMS-DBC; low temperature (LT) fine red needles and high temperature (HT) large yellow platelets. Single crystal X-ray crystallography confirms packing structures where the LT crystals form a 1D slipped-stack structure, while the HT crystals adopt a 2D brickwork motif. These polymorphs also represent a rare example where both are extremely stable and do not interconvert to the other crystal structure upon solvent or thermal annealing. Single crystal organic field-effect transistors of the LT and HT crystals show that the HT 2D brickwork motif produces hole mobilities as high as 2.1 cm2 V-1 s-1, while the mobility of the 1D structure is significantly lower, at 0.028 cm2 V-1 s-1. Electronic-structure calculations indicate that the superior charge transport in the brickwork polymorph in comparison to the slipped-stack polymorph is due to the presence of an increased dimensionality of the charge migration pathways.

  19. Temperature-mediated polymorphism in molecular crystals: The impact on crystal packing and charge transport

    KAUST Repository

    Stevens, Loah A.

    2015-01-13

    We report a novel synthesis to ultra high purity 7,14-bis((trimethylsilyl)ethynyl)dibenzo[b,def]-chrysene (TMS-DBC) and the use of this material in the growth of single crystals by solution and vapor deposition techniques. We observe that the substrate temperature has a dramatic impact on the crystal growth, producing two distinct polymorphs of TMS-DBC; low temperature (LT) fine red needles and high temperature (HT) large yellow platelets. Single crystal X-ray crystallography confirms packing structures where the LT crystals form a 1D slipped-stack structure, while the HT crystals adopt a 2D brickwork motif. These polymorphs also represent a rare example where both are extremely stable and do not interconvert to the other crystal structure upon solvent or thermal annealing. Single crystal organic field-effect transistors of the LT and HT crystals show that the HT 2D brickwork motif produces hole mobilities as high as 2.1 cm2 V-1 s-1, while the mobility of the 1D structure is significantly lower, at 0.028 cm2 V-1 s-1. Electronic-structure calculations indicate that the superior charge transport in the brickwork polymorph in comparison to the slipped-stack polymorph is due to the presence of an increased dimensionality of the charge migration pathways.

  20. Low temperature deformation mechanisms in LiF single crystals

    International Nuclear Information System (INIS)

    Fotedar, H.L.; Stroebe, T.G.

    1976-01-01

    An analysis of the deformation behavior of high purity LiF single crystals is given using yielding and work hardening data and thermally activated deformation parameters obtained in the temperature range 77-423 0 K. It is found that while the Fleischer mechanism is apparently valid experimentally over the thermally activated temperature range, vacancies produced in large numbers at 77 0 K could also play a role in determining the critical resolved shear stress at that temperature

  1. Endoscopic forehead lift in patients with male pattern baldness.

    Science.gov (United States)

    Shipchandler, Taha Z; Sultan, Babar; Byrne, Patrick J

    2012-01-01

    The presence of male pattern baldness poses a significant challenge when attempting to optimize treatment of the upper third of the face. The purpose of this study is to demonstrate and discuss results of the endoscopic forehead lift in patients with male pattern baldness. This was a retrospective case series done in an academic medical center. Eleven patients with male pattern baldness (Norwood class IV-VII) underwent endoscopic forehead lift for forehead creases and brow ptosis. All patients achieved smoothing of the forehead and elevation of the brow with no scalp anesthesia at 1 month postoperatively. All patients were pleased with the healing of their incisions in midline, paramedian, and temporal regions. Alloplastic fixation devices used were visible postoperatively in 2 patients initially. The endoscopic forehead lift is a suitable approach for treating the upper third of the face in the presence of male pattern baldness. The use of alloplastic fixation devices may be used in this patient population, but other fixation methods should be considered. Copyright © 2012 Elsevier Inc. All rights reserved.

  2. Transitions through critical temperatures in nematic liquid crystals

    KAUST Repository

    Majumdar, Apala; Ockendon, John; Howell, Peter; Surovyatkina, Elena

    2013-01-01

    We obtain estimates for critical nematic liquid crystal (LC) temperatures under the action of a slowly varying temperature-dependent control variable. We show that biaxiality has a negligible effect within our model and that these delay estimates are well described by a purely uniaxial model. The static theory predicts two critical temperatures: the supercooling temperature below which the isotropic phase loses stability and the superheating temperature above which the ordered nematic states do not exist. In contrast to the static problem, the isotropic phase exhibits a memory effect below the supercooling temperature in the dynamic framework. This delayed loss of stability is independent of the rate of change of temperature and depends purely on the initial value of the temperature. We also show how our results can be used to improve estimates for LC material constants. © 2013 American Physical Society.

  3. Transitions through critical temperatures in nematic liquid crystals

    KAUST Repository

    Majumdar, Apala

    2013-08-06

    We obtain estimates for critical nematic liquid crystal (LC) temperatures under the action of a slowly varying temperature-dependent control variable. We show that biaxiality has a negligible effect within our model and that these delay estimates are well described by a purely uniaxial model. The static theory predicts two critical temperatures: the supercooling temperature below which the isotropic phase loses stability and the superheating temperature above which the ordered nematic states do not exist. In contrast to the static problem, the isotropic phase exhibits a memory effect below the supercooling temperature in the dynamic framework. This delayed loss of stability is independent of the rate of change of temperature and depends purely on the initial value of the temperature. We also show how our results can be used to improve estimates for LC material constants. © 2013 American Physical Society.

  4. Single Crystal Synthesis and STM Studies of High Temperature Superconductors

    Science.gov (United States)

    Barrientos, Alfonso

    1997-01-01

    This is a final report for the work initiated in September of 1994 under the grant NAG8-1085 - NASA/OMU, on the fabrication of bulk and single crystal synthesis, specific heat measuring and STM studies of high temperature superconductors. Efforts were made to fabricate bulk and single crystals of mercury based superconducting material. A systematic thermal analysis on the precursors for the corresponding oxides and carbonates were carried out to synthesized bulk samples. Bulk material was used as seed in an attempt to grow single crystals by a two-step self flux process. On the other hand bulk samples were characterized by x-ray diffraction, electrical resistivity and magnetic susceptibility, We studied the specific heat behavior in the range from 80 to 300 K. Some preliminary attempts were made to study the atomic morphology of our samples. As part of our efforts we built an ac susceptibility apparatus for measuring the transition temperature of our sintered samples.

  5. Crystallization of Polymers Investigated by Temperature-Modulated DSC

    Directory of Open Access Journals (Sweden)

    Maria Cristina Righetti

    2017-04-01

    Full Text Available The aim of this review is to summarize studies conducted by temperature-modulated differential scanning calorimetry (TMDSC on polymer crystallization. This technique can provide several advantages for the analysis of polymers with respect to conventional differential scanning calorimetry. Crystallizations conducted by TMDSC in different experimental conditions are analysed and discussed, in order to illustrate the type of information that can be deduced. Isothermal and non-isothermal crystallizations upon heating and cooling are examined separately, together with the relevant mathematical treatments that allow the evolution of the crystalline, mobile amorphous and rigid amorphous fractions to be determined. The phenomena of ‘reversing’ and ‘reversible‘ melting are explicated through the analysis of the thermal response of various semi-crystalline polymers to temperature modulation.

  6. Temperature dependence of the dispersion of single crystals SrCl/sub 2/. [Temperature coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Kuzin, M P [L' vovskij Gosudarstvennyj Univ. (Ukrainian SSR)

    1976-01-01

    The dispersion of the refractive index of SrCl/sub 2/ monocrystals in the spectral range 300-700 nm at temperatures of 223, 295 adn 373 K has been studied. The temperature coefficient of the refractive index as a function of the wave length has been determined for the room temperature. The function resembles the corresponding dependence for alkali-halide crystals.

  7. Photonic Crystal Fiber Sensors for Strain and Temperature Measurement

    Directory of Open Access Journals (Sweden)

    Jian Ju

    2009-01-01

    Full Text Available This paper discusses the applications of photonic crystal fibers (PCFs for strain and temperature measurement. Long-period grating sensors and in-fiber modal interferometric sensors are described and compared with their conventional single-mode counterparts. The strain sensitivities of the air-silica PCF sensors are comparable or higher than those implemented in conventional single-mode fibers but the temperature sensitivities of the PCF sensors are much lower.

  8. Growth of high-temperature superconductor crystals from flux

    International Nuclear Information System (INIS)

    Demianets, L.N.; Bykov, A.B.; Melnikov, O.K.; Stishov, S.M.

    1991-01-01

    Crystallization of high-temperature superconductors was studied in La-Sr-Cu-O, Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O systems. Platelet crystals YBa 2 Cu 3 Osub(6.5+x) were obtained by spontaneous crystallization from homogeneous nonstoichiometric melts enriched in barium and copper oxides. Lasub(2-x)Sr x CuO 4 was prepared by slow cooling of melts enriched in copper oxide. Bi 2 (Sr, Ca)sub(n+1)Cu n O y , (n=1;2) was obtained by melting zone travelling. The crystals show transition to superconducting state at T=93K, ΔT 0.2-0.5 K (Y, Ba cuprate), T=87K, ΔT 2K (Bi, Sr, Ca-cuprate). La, Sr-cuprate single crystals obtained by Czochralski method did not show transition to superconducting state. For flux-grown crystals T c was 5-26 K depending on the composition, growth and heat treatment. The short characterization of some accessory phases (Ba 3 Y 2 Cu 3 PtO 10 , Casub(1.75)Srsub(1.5)Cusub(0.75)PtO 6 , BaCuO 2 , Ba 41 Cu 44 O 84 Cl 2 ) is reported. (author). 15 ref s., 8 figs

  9. Remote non-endoscopic hairline approach for excision of forehead ...

    African Journals Online (AJOL)

    Background: Facial mutilation may cause socio-psychological effect on an individual. Surgery on the face can cause some level of anxiety as regards the resulting scar. We hereby present our study on the level of satisfaction among patients who had their forehead lipectomy via a remote hairline access. Patients and ...

  10. The rotational temperature of polar molecular ions in Coulomb crystals

    International Nuclear Information System (INIS)

    Bertelsen, Anders; Joergensen, Solvejg; Drewsen, Michael

    2006-01-01

    With MgH + ions as a test case, we investigate to what extent the rotational motion of smaller polar molecular ions sympathetically cooled into Coulomb crystals in linear Paul traps couples to the translational motions of the ion ensemble. By comparing the results obtained from rotational resonance-enhanced multiphoton photo-dissociation experiments with data from theoretical simulations, we conclude that the effective rotational temperature exceeds the translational temperature (<100 mK) by more than two orders of magnitude, indicating a very weak coupling. (letter to the editor)

  11. High temperature luminescence of ZnSe:Yb crystals

    Directory of Open Access Journals (Sweden)

    Makhniy V. P.

    2016-05-01

    Full Text Available The problem of obtaining of effective edge luminescence with high temperature stability in the zinc selenide crystals is discussed. This task is solved by using as the dopant rare-earth element yttrium, which is introduced into the undoped ZnSe crystal by diffusion method. Doping was carried out in an evacuated to 10 -4 Torr. and a sealed quartz ampoule, in the opposite ends of which is a sample and a mixture of the crushed Yb and Se. It has been found that the diffusion coefficient of yttrium at a temperature of 1400 K is about 5⋅10 -7 cm 2/sec. It is shown that in the luminescence spectra of ZnSe:Yb samples in the temperature range 295-470 K only blue band is observed. Dependencies of parameters of this band from the excitation level are typical for the annihilation of excitons at their inelastic scattering by free carriers. The efficacy of blue radiation at 300 K is about 30% and does not fall more than twice with increasing temperature up to 470 K, indicating its high thermal stability.

  12. Temperature and fluence effects in lead implanted cobalt single crystals

    International Nuclear Information System (INIS)

    Johansen, A.; Sarholt-Kristensen, L.; Johnson, E.; Steenstrup, S.; Chernysh, V.S.

    1988-01-01

    The channeled sputtering yields of the hcp and fcc phases of cobalt depend on the crystal structure and the radiation induced damage. Earlier irradiations of cobalt with argon ions channeled in the hcp direction give sputtering yields higher than expected in the temperature range 100-350deg C. This effect was attributed to a combination of radiation induced damage and a possible implantation induced hcp --> fcc phase transition. Sputtering yields for cobalt single crystals irradiated with 150 keV Pb + ions along the direction of the hcp phase and the direction of the fcc phase have been measured using the weightloss method. The radiation damage and the amount of lead retained in the implanted surface has been investigated by 'in situ' RBS/channeling analysis. Measured partial sputtering yields of lead ≅ 1 atom/ion indicate preferential sputtering of lead atoms. (orig.)

  13. Unusual Forehead Tremor in Four Patients with Essential Tremor

    OpenAIRE

    Gascón-Bayarri, Jordi; Campdelacreu, Jaume; Calopa, Màtil; Jaumà, Serge; Bau, Laura; Povedano, Mònica; Montero, Jordi

    2012-01-01

    Forehead tremor has only been reported in two patients with essential tremor, one with rhythmic tremor and the other with dystonic tremor. We report 4 new patients with essential tremor who present a 4–6 Hz frontal tremor registered by electromyography and unusual features like frontal tremor preceding limb tremor or unilateral involvement. Frontal tremor is present in some patients with essential tremor, sometimes preceding limb tremor. Treatment with botulinum toxin may be useful.

  14. Unusual Forehead Tremor in Four Patients with Essential Tremor

    Directory of Open Access Journals (Sweden)

    Jordi Gascón-Bayarri

    2012-01-01

    Full Text Available Forehead tremor has only been reported in two patients with essential tremor, one with rhythmic tremor and the other with dystonic tremor. We report 4 new patients with essential tremor who present a 4–6 Hz frontal tremor registered by electromyography and unusual features like frontal tremor preceding limb tremor or unilateral involvement. Frontal tremor is present in some patients with essential tremor, sometimes preceding limb tremor. Treatment with botulinum toxin may be useful.

  15. Controlling Active Liquid Crystal Droplets with Temperature and Surfactant Concentration

    Science.gov (United States)

    Shechter, Jake; Milas, Peker; Ross, Jennifer

    Active matter is the study of driven many-body systems that span length scales from flocking birds to molecular motors. A previously described self-propelled particle system was made from liquid crystal (LC) droplets in water with high surfactant concentration to move particles via asymmetric surface instabilities. Using a similar system, we investigate the driving activity as a function of SDS surfactant concentration and temperature. We then use an optical tweezer to trap and locally heat the droplets to cause hydrodynamic flow and coupling between multiple droplets. This system will be the basis for a triggerable assembly system to build and couple LC droplets. DOD AROMURI 67455-CH-MUR.

  16. High temperature microhardness of ZrB2 single crystals

    International Nuclear Information System (INIS)

    Yi Xuan; Chen Chunhua; Otani, Shigeki

    2002-01-01

    Vickers microhardness of (0001), (101-bar 0) and (112-bar 0) planes of ZrB 2 single crystal prepared by the floating zone method has been investigated at various temperatures and loading times. As the temperature increases from 25 deg. C to 1000 deg. C, hardness drops from ∼20.9 GN m -2 of all planes to ∼7.85 GN m -2 for (0001) plane and ∼4.91 GN m -2 for (101-bar 0) and (112-bar 0) planes. The hardness of (101-bar 0) and (112-bar 0) planes exhibits almost same tendency and is always lower than that of (0001) plane by about 35%. The thermal softening coefficients of all three planes strongly depends on the temperature range with clear inflections at 400 deg. C and 700 deg. C. The loading time dependence of hardness is used to calculate the activation energy for creep. In addition, a relationship was found that shows the variation of hardness with temperature to be proportional to the variation with the loading time in a specific temperature range. (rapid communication)

  17. Effect of solvent and temperature on solution-crystallized terfenadine

    International Nuclear Information System (INIS)

    Leitao, M. Luisa P.; Canotilho, Joao; Ferreira, Simone C.R.; Sousa, Adriano T.; Simoes Redinha, J.

    2004-01-01

    The aim of this work was to understand the crystallization process of terfenadine in solution. Cooling of saturated solutions prepared at 50 deg. C at different temperatures, evaporating the solvent from nearly saturated solutions at a certain temperature, and exposing ethanol solutions of terfenadine to water vapour atmosphere were the techniques used for obtaining terfenadine specimens. The characterization of these specimens was carried out by thermal microscopy, differential thermal analysis, thermogravimetry and powder X-ray diffraction. Crystalline phases, amorphous solids, and solvates were identified. For the solvents used in the present study, the crystallinity degree of terfenadine decreases from ethanol-water to ethanol and from this to methanol. Decreasing the temperature promotes the formation of amorphous solid material; at low temperatures, methanol and ethanol solvates are also formed. Desolvation, following the terfenadine aggregation process in solution accounts for the different behaviour found for the solvents and for the effect of temperature on the structure. The role of the solvent as structure-mediator is explained on the grounds of the values previously published for the enthalpy of solution of terfenadine in the solvents under study

  18. Temperature dependence of magnetoresistance in copper single crystals

    Science.gov (United States)

    Bian, Q.; Niewczas, M.

    2018-03-01

    Transverse magnetoresistance of copper single crystals has been measured in the orientation of open-orbit from 2 K to 20 K for fields up to 9 T. The experimental Kohler's plots display deviation between individual curves below 16 K and overlap in the range of 16 K-20 K. The violation of the Kohler's rule below 16 K indicates that the magnetotransport can not be described by the classical theory of electron transport on spherical Fermi surface with a single relaxation time. A theoretical model incorporating two energy bands, spherical and cylindrical, with different relaxation times has been developed to describe the magnetoresistance data. The calculations show that the electron-phonon scattering rates at belly and neck regions of the Fermi surface have different temperature dependencies, and in general, they do not follow T3 law. The ratio of the relaxation times in belly and neck regions decreases parabolically with temperature as A - CT2 , with A and C being constants.

  19. Molecular Weight and Crystallization Temperature Effects on Poly(ethylene terephthalate (PET Homopolymers, an Isothermal Crystallization Analysis

    Directory of Open Access Journals (Sweden)

    Leonardo A. Baldenegro-Perez

    2014-02-01

    Full Text Available The isothermal crystallization of poly(ethylene terephthalate (PET homopolymers with different molecular weight was studied in a wide temperature range (140–230 °C using different experimental techniques. Three different morphological regions, labeled r1, r2 and r3, were distinguished as a function of crystallization temperature (Tc. In r1 (low Tc crystallized samples were characterized by a low crystalline degree with a small spherulite texture containing thin crystals. In r2 (intermediate Tc samples showed medium size spherulites composed of two distinct crystalline families (thin and thick crystals. In this temperature range, the crystallization exhibited a maximum value and it was associated with a high content of secondary crystals. In r3 (high Tc, samples presented considerable amorphous zones and regions consisting of oversized spherulites containing only thick crystals. Time-resolved wide-angle X-ray diffraction measurements, using synchrotron radiation, indicated a rapid evolution of the crystalline degree within the second region, in contrast with the quite slow evolution observed in the third region. On the other hand, by small-angle X-ray scattering (SAXS and time-resolved SAXS experiment, it was found that the long period (L as well as the lamellar thickness (lc increase as a function of Tc, corroborating the formation of the thickest crystals in the third region. From all these observations, a morphological model was proposed for each region.

  20. Temperature effect on phase states of quartz nano-crystals in silicon single crystal

    International Nuclear Information System (INIS)

    Kalanov, M.U.; Ibragimova, E.M.; Khamraeva, R.N.; Rustamova, V.M.; Ummatov, Kh.D.

    2006-01-01

    Full text: Oxygen penetrates into the silicon lattice up to the concentration of 2·10 18 cm -3 in the course of growing [1]. By the author's opinion at a low oxygen content the formation of solid solution is possible in the local defect places of the silicon single crystal lattice due to the difference in effective ion radius of oxygen and silicon (r O 0.176 and r Si = 0.065 nm). Upon reaching some critical content (∼ 10 17 cm -3 ), it becomes favorable energetically for oxygen ions to form precipitates (SiO x ) and finally a dielectric layer (stoichiometric inclusions of SiO 2 ). It was shown later that depending on the growth conditions, indeed the quartz crystal inclusions are formed in the silicon single crystals at an amount of 0.3 /0.5 wt. % [2]. However the authors did not study a phase state of the quartz inclusions. Therefore the aim of this work was to study a phase state of the quartz inclusions in silicon crystal at various temperatures. We examined the silicon single crystals grown by Czochralski technique, which were cut in (111) plane in the form of disk of 20 mm diameter and 1.5 thickness and had hole conductivity with the specific resistance ρ o ≅ 1/10 Ohm cm. The dislocation density was N D ≅ 10 1 /10 3 cm -2 , the concentrations of oxygen and boron were N 0 ≅ 2/ 4·10 17 cm -3 and N B ≅ 3*10 15 cm -3 . Structure was analyzed at the set-up DRON-UM1 with high temperature supply UVD-2000 ( CuK = 0.1542 nm) at the temperatures of 300, 1173 and 1573 K measured with platinum-platinum-rhodium thermocouple. The high temperature diffraction spectrum measured at 1573 K in the angle range (2Θ≅10/70 d egree ) there is only one main structure reflection (111) with a high intensity and d/n ≅ 0.3136 nm (2 Θ≅ 28.5 d egree ) from the matrix lattice of silicon single crystal. The weak line at 2 Θ≅ 25.5 d egree ( d/n≅0.3136 nm) is β component of the main reflection (111), and the weak structure peak at 2Θ≅59 d egree ( d/n≅ 0.1568 nm

  1. Study of the possibility of growing germanium single crystals under low temperature gradients

    Science.gov (United States)

    Moskovskih, V. A.; Kasimkin, P. V.; Shlegel, V. N.; Vasiliev, Y. V.; Gridchin, V. A.; Podkopaev, O. I.; Zhdankov, V. N.

    2014-03-01

    The possibility of growing germanium single crystals under low temperature gradients in order to produce a dislocation-free material has been studied. Germanium crystals with a dislocation density of about 100-200 cm-2 have been grown in a system with a weight control of crystal growth at maximum axial gradients of about 1.5 K/cm.

  2. Polymorphic crystallization of metal-metalloid-glasses above the glass transition temperature

    International Nuclear Information System (INIS)

    Koster, U.; Schunemann, U.; Stephenson, G.B.; Brauer, S.; Sutton, M.

    1992-01-01

    Crystallization of metal-metalloid glasses is known to proceed by nucleation and growth processes. Using crystallization statistics in partially crystallized glasses, at temperatures below the glass transition temperature, time-dependent heterogeneous nucleation has been found to occur at a number of quenched-in nucleation sites. Close to the glass transition temperature crystallization proceeds so rapidly that partially crystallized microstructures could not be obtained. Initial results form fully crystallized glasses exhibit evidence for a transient homogeneous nucleation process at higher temperatures. These conclusions are derived post mortem. At there may be some change of the microstructure after crystallization is finished or during he subsequent quenching, it is desirable to directly obtain information during the early stages of crystallization. Recently reported work by Sutton et al. showed that structural changes can be observed in situ during crystallization by time-resolved x-ray diffraction on time scales as short as milliseconds. The aim o the paper is to present the authors study of the crystallization behavior at temperatures near the glass transition by in-situ x-ray diffraction studies and by microstructural analysis after rapid heating experiments. The results are compared to those derived from a computer model of the crystallization process

  3. Mechanical properties of low temperature proton irradiated single crystal copper

    International Nuclear Information System (INIS)

    Schildcrout, M.

    1975-01-01

    Single crystal copper samples, of varying degrees of cold work, were irradiated near either liquid helium or liquid nitrogen temperature by 10.1-MeV protons. The internal friction and dynamic Young's modulus were observed as a function of either temperature or integrated proton flux. The primary effect of irradiation was to produce dislocation pinning. The initial pinning rate was found to be very sensitive to cold work. During irradiation it was found that heavily cold worked samples (25 percent compression) exhibited, almost exclusively, exponential pinning given by Y = e/sup --lambda phi/. This is attributed to the immobilization, rather than shortening, of loop lengths and is characterized by the pinning constant lambda. Exponential pinning was also found, to a smaller degree, in less heavily cold worked samples. Cold work appears to reduce the ''effective volume'' within which the defect clusters produced by irradiation, can immobilize dislocation segments. The bulk effect was observed after dislocation pinning was completed. Expressed in terms of the fractional change in Young's modulus per unit concentration of irradiation induced defects, it was measured at liquid helium temperature to be --18.5 +- 3. An anelastic process occurring near 10 0 K for low kHz frequencies and due to stress-induced ordering of point defects produced by irradiation has also been studied. The peak height per unit fluence was found to decrease with increasing cold work. The peak was not observed in samples compressed 25 percent. For the most carefully handled sample the activation energy was (1.28 +- 0.05) x 10 -2 eV, the attempt frequency was 10/sup 11.6 +- .8/ s -1 , the shape factor was 0.20, and the half width of the peak was 11 percent larger than the theoretical value calculated from the Debye equation for a single relaxation process

  4. Optical power limiting and transmitting properties of cadmium iodide single crystals: Temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish, E-mail: m.miah@griffith.edu.a [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)] [Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)] [Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

    2009-09-14

    Optical limiting properties of the single crystals of cadmium iodide are investigated using ns laser pulses. It is found that the transmissions in the crystals increase with increasing temperature. However, they limit the transmissions at high input powers. The limiting power is found to be higher at higher temperature. From the measured transmission data, the photon absorption coefficients are estimated. The temperature dependence of the coefficients shows a decrease in magnitude with increasing temperature. This might be due to the temperature-dependent bandgap shift of the material. The results demonstrate that the cadmium iodide single crystals are promising materials for applications in optical power limiting devices.

  5. Optical power limiting and transmitting properties of cadmium iodide single crystals: Temperature dependence

    International Nuclear Information System (INIS)

    Miah, M. Idrish

    2009-01-01

    Optical limiting properties of the single crystals of cadmium iodide are investigated using ns laser pulses. It is found that the transmissions in the crystals increase with increasing temperature. However, they limit the transmissions at high input powers. The limiting power is found to be higher at higher temperature. From the measured transmission data, the photon absorption coefficients are estimated. The temperature dependence of the coefficients shows a decrease in magnitude with increasing temperature. This might be due to the temperature-dependent bandgap shift of the material. The results demonstrate that the cadmium iodide single crystals are promising materials for applications in optical power limiting devices.

  6. Monochromator for synchrotron light with temperature controlled by electrical current on silicon crystal

    Energy Technology Data Exchange (ETDEWEB)

    Cusatis, Cesar; Souza, Paulo E.N. [Universidade Federal do Parana (LORXI/UFPR), Curitiba, PR (Brazil). Dept. de Fisica. Lab. de Optica de Raios X e Instrumentacao; Franco, Margareth Kobayaski; Kakuno, Edson [Laboratorio Nacional de Luz Sincroton (LNLS), Campinas, SP (Brazil); Gobbi, Angelo; Carvalho Junior, Wilson de [Centro de Pesquisa e Desenvolvimento em Telecomunicacoes (CPqD), Campinas, SP (Brazil)

    2011-07-01

    Full text. doped silicon crystal was used simultaneously as a monochromator, sensor and actuator in such way that its temperature could be controlled. Ohmic contacts allowed resistance measurements on a perfect silicon crystal, which were correlated to its temperature. Using the ohmic contacts, an electrical current caused Joule heating on the monochromator that was used to control its temperature. A simple stand-alone electronic box controlled the system. The device was built and tested with white beam synchrotron light on the double crystal monochromator of the XRD line of LNLS, Laboratorio Nacional de Luz Sincrotron, Campinas. The first crystal of a double crystal monochromator determines the energy that is delivered to a synchrotron experimental station and its temperature instability is a major source of energy and intensity instability. If the (333) silicon monochromator is at theta Bragg near 45 degree the variation of the diffraction angle is around one second of arc per degree Kelvin. It may take several minutes for the first crystal temperature to stabilize at the beginning of the station operation when the crystal and its environment are cold. With water refrigeration, the average overall temperature of the crystal may be constant, but the temperature of the surface changes with and without the white beam. The time used to wait for stabilization of the beam energy/intensity is lost unless the temperature of the crystal surface is kept constant. One solution for keeping the temperature of the monochromator and its environment constant or nearly constant is Joule heating it with a controlled small electrical current flowing on the surface of a doped perfect crystal. When the white beam is on, this small amount of extra power will be more concentrated at the beam footpath because the resistance is lower in this region due to the higher temperature. In addition, if the crystal itself is used to detect the temperature variation by measuring the electrical

  7. Boron lattice location in room temperature ion implanted Si crystal

    International Nuclear Information System (INIS)

    Piro, A.M.; Romano, L.; Mirabella, S.; Grimaldi, M.G.

    2005-01-01

    The B lattice location in presence of a Si-self-interstitial (I Si ) supersaturation, controlled by energetic proton bombardment, has been studied by means of ion channelling and massive Monte Carlo simulations. B-doped layers of Si crystals with a B concentration of 1 x 10 2 B/cm 3 were grown by Molecular Beam Epitaxy. Point defect engineering techniques, with light energetic ion implants, have been applied to generate an I Si uniform injection in the electrically active layer. The displacement of B atoms out of substitutional lattice sites was induced by 650 keV proton irradiations at room temperature (R.T.) and the resultant defect configuration was investigated by ion channelling and Nuclear Reaction Analysis (NRA) techniques. Angular scans were measured both through and axes along the (1 0 0) plane using the 11 B(p,α) 8 Be nuclear reaction at 650 keV proton energy. Monte Carlo simulated angular scans were calculated considering a variety of theoretical defect configurations, supported by literature, and compared with experimental data. Our experimental scans can be fitted by a linear combination of small (0.3 A) and large B displacements (1.25 A) along the direction, compatible with the B-dumbbell oriented along as proposed by ab initio calculations

  8. Time lapse microscopy of temperature control during self-assembly of 3D DNA crystals

    Science.gov (United States)

    Conn, Fiona W.; Jong, Michael Alexander; Tan, Andre; Tseng, Robert; Park, Eunice; Ohayon, Yoel P.; Sha, Ruojie; Mao, Chengde; Seeman, Nadrian C.

    2017-10-01

    DNA nanostructures are created by exploiting the high fidelity base-pairing interactions of double-stranded branched DNA molecules. These structures present a convenient medium for the self-assembly of macroscopic 3D crystals. In some self-assemblies in this system, crystals can be formed by lowering the temperature, and they can be dissolved by raising it. The ability to monitor the formation and melting of these crystals yields information that can be used to monitor crystal formation and growth. Here, we describe the development of an inexpensive tool that enables direct observation of the crystal growth process as a function of both time and temperature. Using the hanging-drop crystallization of the well-characterized 2-turn DNA tensegrity triangle motif for our model system, its response to temperature has been characterized visually.

  9. Auto-oscillations of temperature and defect density in impure crystals under irradiation

    International Nuclear Information System (INIS)

    Selishchev, P.A.; Sugakov, V.I.

    1990-01-01

    Appearance of auto-oscillations in temperature and defect density of impurity crystals under irradiation is studied. It is shown that at certain critical parameters stationary distribution of temperature and defect density of the sample irradiated becomes unstable as regards the formation of temporal dissipative structures: auto-oscillations of temperature and defect density. Critical parameters are determined (the rate of defect formation, temperature of crystal environment, etc.) and the frequency of appearing auto-oscillations, its dependence on irradiation conditions and crystal properties are found

  10. Low-temperature crystallization of amorphous silicon and amorphous germanium by soft X-ray irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Heya, Akira, E-mail: heya@eng.u-hyogo.ac.jp [Department of Materials Science and Chemistry, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671–2280 (Japan); Kanda, Kazuhiro [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Toko, Kaoru; Sadoh, Taizoh [Department of Electronics, Kyushu University, 744 Nishi-ku, Motooka, Fukuoka 819–0395 (Japan); Amano, Sho [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Matsuo, Naoto [Department of Materials Science and Chemistry, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671–2280 (Japan); Miyamoto, Shuji [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan); Miyao, Masanobu [Department of Electronics, Kyushu University, 744 Nishi-ku, Motooka, Fukuoka 819–0395 (Japan); Mochizuki, Takayasu [Laboratory of Advanced Science and Technology for Industry (LASTI), University of Hyogo, 3-2-1 Koto, Kamigori, Hyogo 678–1205 (Japan)

    2013-05-01

    The low-temperature-crystallization effects of soft X-ray irradiation on the structural properties of amorphous Si and amorphous Ge films were investigated. From the differences in crystallization between Si and Ge, it was found that the effects of soft X-ray irradiation on the crystallization strongly depended on the energy band gap and energy level. The crystallization temperatures of the amorphous Si and amorphous Ge films decreased from 953 K to 853 K and 773 K to 663 K, respectively. The decrease in crystallization temperature was also related to atoms transitioning into a quasi-nucleic phase in the films. The ratio of electron excitation and migration effects to thermal effects was controlled using the storage-ring current (photon flux density). Therefore, we believe that low-temperature crystallization can be realized by controlling atomic migration through electron excitation. - Highlights: • This work investigates the crystallization mechanism for soft X-ray irradiation. • The soft X-ray crystallization depended on the energy band gap and energy level. • The decrease in the crystallization temperature for Si and Ge films was 100 K. • This decrement was related to atoms transitioning into a quasi-nucleic phase.

  11. Synthesis and characterization of L-tyrosine hydrochloride crystals submitted to high and low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Santos, C.A.A.S.; Facanha Filho, P.F.; Ribeiro, L.H.L.; Victor, F.M.S.; Abreu, D.C.; Santos, A.O. dos; Carvalho, J.O.; Soares, R.A.; Sousa, J.C.F.; Lima, R.C.; Cavaignac, A.O. [Universidade Federal do Maranhao (UFMA), MA (Brazil)

    2016-07-01

    Full text: New materials are emerging and generate advances in nonlinear optics that studies the phenomena related to changes in optical properties when occurs interaction of light with the matter. Semi organic crystals present such properties. The goal is this work is to produce semi organic single crystal of L-tyrosine hydrochloride (LTHCl) and verify their thermal stability when subjected to high and low temperatures. The single crystals of LTHCl were produced for solubilization of amino acid L-tyrosine in hydrochloric acid using slow solvent evaporation technique at a constant temperature of 25 deg C. The X-ray diffraction (XRD) and refining by the Rietveld method were used to confirm the structure of the material. The thermal stability was investigated using DSC, TGA-DTA. The LTHCl crystal belongs to the monoclinic system, with two molecules per unit cell. The refinement by the Rietveld method showed good results with Rwp= 8.49% and Rp= 6.29% with S=1.13. Thermal analysis shown an endothermic event at about 160°C, which can be associated with phase transition occurred in LTHCl crystal. It was also observed that the crystal melting point occurs at a temperature of 230°C. No water of crystallization was found in the crystal structure, which was confirmed by Raman spectroscopy and thermal analysis. From the Raman spectroscopy experiments in function of temperature, no significant changes was observe in the behavior of vibrational normal modes between temperatures of -253 and 170 deg C. Finally, a monoclinic crystal system LTHCl is stable up to 160°C at high temperatures and -253°C at low temperatures. Therefore, our investigation has proved that LTHCl crystals can be used in this range of temperature without the lost of their nonlinear optical properties. (author)

  12. Supersaturation Control using Analytical Crystal Size Distribution Estimator for Temperature Dependent in Nucleation and Crystal Growth Phenomena

    Science.gov (United States)

    Zahari, Zakirah Mohd; Zubaidah Adnan, Siti; Kanthasamy, Ramesh; Saleh, Suriyati; Samad, Noor Asma Fazli Abdul

    2018-03-01

    The specification of the crystal product is usually given in terms of crystal size distribution (CSD). To this end, optimal cooling strategy is necessary to achieve the CSD. The direct design control involving analytical CSD estimator is one of the approaches that can be used to generate the set-point. However, the effects of temperature on the crystal growth rate are neglected in the estimator. Thus, the temperature dependence on the crystal growth rate needs to be considered in order to provide an accurate set-point. The objective of this work is to extend the analytical CSD estimator where Arrhenius expression is employed to cover the effects of temperature on the growth rate. The application of this work is demonstrated through a potassium sulphate crystallisation process. Based on specified target CSD, the extended estimator is capable of generating the required set-point where a proposed controller successfully maintained the operation at the set-point to achieve the target CSD. Comparison with other cooling strategies shows a reduction up to 18.2% of the total number of undesirable crystals generated from secondary nucleation using linear cooling strategy is achieved.

  13. Architecture of the sperm whale forehead facilitates ramming combat

    Directory of Open Access Journals (Sweden)

    Olga Panagiotopoulou

    2016-04-01

    Full Text Available Herman Melville’s novel Moby Dick was inspired by historical instances in which large sperm whales (Physeter macrocephalus L. sank 19th century whaling ships by ramming them with their foreheads. The immense forehead of sperm whales is possibly the largest, and one of the strangest, anatomical structures in the animal kingdom. It contains two large oil-filled compartments, known as the “spermaceti organ” and “junk,” that constitute up to one-quarter of body mass and extend one-third of the total length of the whale. Recognized as playing an important role in echolocation, previous studies have also attributed the complex structural configuration of the spermaceti organ and junk to acoustic sexual selection, acoustic prey debilitation, buoyancy control, and aggressive ramming. Of these additional suggested functions, ramming remains the most controversial, and the potential mechanical roles of the structural components of the spermaceti organ and junk in ramming remain untested. Here we explore the aggressive ramming hypothesis using a novel combination of structural engineering principles and probabilistic simulation to determine if the unique structure of the junk significantly reduces stress in the skull during quasi-static impact. Our analyses indicate that the connective tissue partitions in the junk reduce von Mises stresses across the skull and that the load-redistribution functionality of the former is insensitive to moderate variation in tissue material parameters, the thickness of the partitions, and variations in the location and angle of the applied load. Absence of the connective tissue partitions increases skull stresses, particularly in the rostral aspect of the upper jaw, further hinting of the important role the architecture of the junk may play in ramming events. Our study also found that impact loads on the spermaceti organ generate lower skull stresses than an impact on the junk. Nevertheless, whilst an impact on the

  14. Architecture of the sperm whale forehead facilitates ramming combat.

    Science.gov (United States)

    Panagiotopoulou, Olga; Spyridis, Panagiotis; Mehari Abraha, Hyab; Carrier, David R; Pataky, Todd C

    2016-01-01

    Herman Melville's novel Moby Dick was inspired by historical instances in which large sperm whales (Physeter macrocephalus L.) sank 19th century whaling ships by ramming them with their foreheads. The immense forehead of sperm whales is possibly the largest, and one of the strangest, anatomical structures in the animal kingdom. It contains two large oil-filled compartments, known as the "spermaceti organ" and "junk," that constitute up to one-quarter of body mass and extend one-third of the total length of the whale. Recognized as playing an important role in echolocation, previous studies have also attributed the complex structural configuration of the spermaceti organ and junk to acoustic sexual selection, acoustic prey debilitation, buoyancy control, and aggressive ramming. Of these additional suggested functions, ramming remains the most controversial, and the potential mechanical roles of the structural components of the spermaceti organ and junk in ramming remain untested. Here we explore the aggressive ramming hypothesis using a novel combination of structural engineering principles and probabilistic simulation to determine if the unique structure of the junk significantly reduces stress in the skull during quasi-static impact. Our analyses indicate that the connective tissue partitions in the junk reduce von Mises stresses across the skull and that the load-redistribution functionality of the former is insensitive to moderate variation in tissue material parameters, the thickness of the partitions, and variations in the location and angle of the applied load. Absence of the connective tissue partitions increases skull stresses, particularly in the rostral aspect of the upper jaw, further hinting of the important role the architecture of the junk may play in ramming events. Our study also found that impact loads on the spermaceti organ generate lower skull stresses than an impact on the junk. Nevertheless, whilst an impact on the spermaceti organ would

  15. Micromechanical properties of C70 single crystals in the temperature range 77-350 K

    International Nuclear Information System (INIS)

    Lubenets, S.V.; Natsik, V.D.; Fomenko, L.S.; Rusakova, A.V.; Natsik, V.D.; Osip'yan, Yu.A.; Orlov, V.I.; Sidorov, N.S.; Izotov, A.N.

    2012-01-01

    Hexagonal single crystals of C 70 up to a size down to 1-2 mm were grown which allowed for the first time to investigate their low-temperature mechanical properties. Morphology, microplasticity anisotropy and the temperature dependence of Vickers microhardness HV (T) of the C 70 crystals in the temperature range 77-350 K involving all known phase transitions have been studied with the aid of optical microscopy and microindentation. The association of the features of HV (T) dependence with orientation phase transformations has been analyzed. It is suggested that anisotropy of microplasticity in the C 70 crystals correlates with the active slip systems.

  16. Dramatic improvement of crystal quality for low-­temperature-grown rabbit muscle aldolase

    OpenAIRE

    Park, HaJeung; Rangarajan, Erumbi S.; Sygusch, Jurgen; Izard, Tina

    2010-01-01

    Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination.

  17. Dramatic improvement of crystal quality for low-temperature-grown rabbit muscle aldolase

    International Nuclear Information System (INIS)

    Park, HaJeung; Rangarajan, Erumbi S.; Sygusch, Jurgen; Izard, Tina

    2010-01-01

    Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA–LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice

  18. Empirical temperature-dependent intermolecular potentials determined by data mining from crystal data

    Science.gov (United States)

    Hofmann, D. W. M.; Kuleshova, L. N.

    2018-05-01

    Modern force fields are accurate enough to describe thermal effects in molecular crystals. Here, we have extended our earlier approach to discrete force fields for various temperatures to a force field with a continuous function. For the parametrisation of the force field, we used data mining on experimental structures with the temperature as an additional descriptor. The obtained force field can be used to minimise energy at a finite temperature and for molecular dynamics with zero-K potentials. The applicability of the method has been demonstrated for the prediction of crystal density, temperature density gradients and transition temperature.

  19. Influence of the laser-diode temperature on crystal absorption and ...

    Indian Academy of Sciences (India)

    Abstract. In this work, we studied the influence of heat loaded into the laser crystal in an end- pumped solid-state Nd:YVO4 high power laser. We have shown experimentally that the optimum value of the laser-diode temperature for the maximum pump power absorption by the Nd:YVO4 crystal and the maximum Nd:YVO4 ...

  20. Formation of temperature fields in doped anisotropic crystals under spatially inhomogeneous light beams passing through them

    Energy Technology Data Exchange (ETDEWEB)

    Zaitseva, E. V.; Markelov, A. S.; Trushin, V. N., E-mail: trushin@phys.unn.ru; Chuprunov, E. V. [Nizhni Novgorod State University (Russian Federation)

    2013-12-15

    The features of formation of thermal fields in potassium dihydrophosphate crystal doped with potassium permanganate under a 532-nm laser beam passing through it have been investigated. Data on the influence of birefringence on the temperature distribution in an anisotropic crystal whose surface is illuminated by a spatially modulated light beam are presented.

  1. Effect of temperature on the morphology and electro-optical properties of liquid crystal physical gel

    International Nuclear Information System (INIS)

    Leaw, W.L.; Mamat, C.R.; Triwahyono, S.; Jalil, A.A.; Bidin, N.

    2016-01-01

    Liquid crystal physical gels were (thermally) prepared with cholesteryl stearate as a gelator in nematic liquid crystal, 4-cyano-4′-pentylbiphenyl. The electro-optical performance of liquid crystal physical gels is almost entirely dependent on the gels' inherent morphology. This study involved an empirical investigation of the relationships among all of the gelation temperature, morphology, and electro-optical properties. Besides continuous cooling at room temperature, isothermal cooling was also performed at both 18 and 0 °C, corresponding to near-solid and solid phases of 4-cyano-4′-pentylbiphenyl respectively. Nevertheless, the liquid crystal physical gel was also isothermally rapidly cooled using liquid nitrogen. Polarizing optical microscopy showed that the gel structure became thinner when isothermal cooling was carried out. These thinner gel aggregates then interconnected to form larger liquid crystal domains. Moreover, it was also revealed that the gel networks were randomized. Electron spin resonance results showed that the liquid crystal director orientation was severely randomized in the presence of gel networks. Conversely, isothermal cooling using liquid nitrogen generated a higher liquid crystal director orientation order. The 6.0 wt% cholesteryl stearate/4-cyano-4′-pentylbiphenyl physical gel that was isothermally cooled using liquid nitrogen showed the lowest response time in a twisted nematic mode optical cell. - Graphical abstract: Liquid crystal physical gel was prepared using nematic liquid crystal, 4-cyano-4′-pentylbiphenyl and cholesteryl stearate as gelator. Isothermal cooling at lower temperature produced thinner gel network and larger liquid crystal domain. - Highlights: • 5CB nematic liquid crystal was successfully gelled by cholesteryl stearate gelator. • The morphology of gel network was controlled by different cooling conditions. • Thinner gel network was formed by the rapid cooling using liquid nitrogen. • Enhanced

  2. Effect of temperature on the morphology and electro-optical properties of liquid crystal physical gel

    Energy Technology Data Exchange (ETDEWEB)

    Leaw, W.L. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Mamat, C.R., E-mail: che@kimia.fs.utm.my [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Triwahyono, S. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Jalil, A.A. [Department of Chemical Engineering, Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Centre of Hydrogen Energy, Institute of Future Energy, Univerisiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Bidin, N. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia)

    2016-12-01

    Liquid crystal physical gels were (thermally) prepared with cholesteryl stearate as a gelator in nematic liquid crystal, 4-cyano-4′-pentylbiphenyl. The electro-optical performance of liquid crystal physical gels is almost entirely dependent on the gels' inherent morphology. This study involved an empirical investigation of the relationships among all of the gelation temperature, morphology, and electro-optical properties. Besides continuous cooling at room temperature, isothermal cooling was also performed at both 18 and 0 °C, corresponding to near-solid and solid phases of 4-cyano-4′-pentylbiphenyl respectively. Nevertheless, the liquid crystal physical gel was also isothermally rapidly cooled using liquid nitrogen. Polarizing optical microscopy showed that the gel structure became thinner when isothermal cooling was carried out. These thinner gel aggregates then interconnected to form larger liquid crystal domains. Moreover, it was also revealed that the gel networks were randomized. Electron spin resonance results showed that the liquid crystal director orientation was severely randomized in the presence of gel networks. Conversely, isothermal cooling using liquid nitrogen generated a higher liquid crystal director orientation order. The 6.0 wt% cholesteryl stearate/4-cyano-4′-pentylbiphenyl physical gel that was isothermally cooled using liquid nitrogen showed the lowest response time in a twisted nematic mode optical cell. - Graphical abstract: Liquid crystal physical gel was prepared using nematic liquid crystal, 4-cyano-4′-pentylbiphenyl and cholesteryl stearate as gelator. Isothermal cooling at lower temperature produced thinner gel network and larger liquid crystal domain. - Highlights: • 5CB nematic liquid crystal was successfully gelled by cholesteryl stearate gelator. • The morphology of gel network was controlled by different cooling conditions. • Thinner gel network was formed by the rapid cooling using liquid nitrogen.

  3. Electrical conductivity of high-purity germanium crystals at low temperature

    Science.gov (United States)

    Yang, Gang; Kooi, Kyler; Wang, Guojian; Mei, Hao; Li, Yangyang; Mei, Dongming

    2018-05-01

    The temperature dependence of electrical conductivity of single-crystal and polycrystalline high-purity germanium (HPGe) samples has been investigated in the temperature range from 7 to 100 K. The conductivity versus inverse of temperature curves for three single-crystal samples consist of two distinct temperature ranges: a high-temperature range where the conductivity increases to a maximum with decreasing temperature, and a low-temperature range where the conductivity continues decreasing slowly with decreasing temperature. In contrast, the conductivity versus inverse of temperature curves for three polycrystalline samples, in addition to a high- and a low-temperature range where a similar conductive behavior is shown, have a medium-temperature range where the conductivity decreases dramatically with decreasing temperature. The turning point temperature ({Tm}) which corresponds to the maximum values of the conductivity on the conductivity versus inverse of temperature curves are higher for the polycrystalline samples than for the single-crystal samples. Additionally, the net carrier concentrations of all samples have been calculated based on measured conductivity in the whole measurement temperature range. The calculated results show that the ionized carrier concentration increases with increasing temperature due to thermal excitation, but it reaches saturation around 40 K for the single-crystal samples and 70 K for the polycrystalline samples. All these differences between the single-crystal samples and the polycrystalline samples could be attributed to trapping and scattering effects of the grain boundaries on the charge carriers. The relevant physical models have been proposed to explain these differences in the conductive behaviors between two kinds of samples.

  4. BiFeO3 Crystal Structure at Low Temperatures

    International Nuclear Information System (INIS)

    Palewicz, A.; Sosnowska, I.; Przenioslo, R.; Hewat, A.W.

    2010-01-01

    The crystal and magnetic structure of BiFeO 3 have been studied with the use of high resolution neutron diffraction between 5 K and 300 K. The atomic coordinates in BiFeO 3 are almost unchanged between 5 K and 300 K. (authors)

  5. Synthesis and room temperature single crystal EPR studies of a ...

    Indian Academy of Sciences (India)

    Unknown

    Hamiltonian parameters calculated from single crystal rotations are: g ... studies on two nickel complexes with SalX ligands (X = NH, NCH3) have shown the ..... here the positive sign is required for a shell that is less than half-filled and the ...

  6. Reconstruction of Nasal Cleft Deformities Using Expanded Forehead Flaps: A Case Series.

    Science.gov (United States)

    Ramanathan, Manikandhan; Sneha, Pendem; Parameswaran, Ananthnarayanan; Jayakumar, Naveen; Sailer, Hermann F

    2014-12-01

    Reconstruction of the nasal clefts is a challenging task considering the nasal anatomic complexity and their possible association with craniofacial defects. The reconstruction of these defects needs extensive amounts of soft tissue that warrant the use of forehead flaps. Often presence of cranial defects and low hairline compromise the amount of tissue available for reconstruction warrenting tissue expansion. To evaluate the efficacy of tissue expansion in reconstruction of congenital nasal clefts. 9 patients with congenital nasal clefts involving multiple sub units were taken up for nasal reconstruction with expanded forehead flaps. The average amount of expansion needed was 200 ml. The reconstruction was performed in 3 stages. Expanded forehead flaps proved to be best modality for reconstruction providing the skin cover needed for ala, columella and dorsum with minimal scarring at the donor site. Expansion of the forehead flap is a viable option for multiple sub unit reconstruction in congenital nasal cleft deformities.

  7. Usage of a rotational flap for coverage of a large central forehead defect

    Directory of Open Access Journals (Sweden)

    El-Sabbagh, Ahmed Hassan

    2017-02-01

    Full Text Available Background: The forehead is a donor site for facial reconstruction but has no generous donor site for its coverage. All options of the reconstructive ladder can be used. A large rotation flap was used to reconstruct a big central forehead defect following failed previous repair in an elderly diabetic patient after a motor car accident. Case presentation: A 64-year-old diabetic man presented with an extensive central forehead defect after failed previous repair following a motor car accident. Coverage of the defect was performed using a flap based around the ear on one side in a rotation movement. An accepted functional and esthetic result was achieved after 3 months of Conclusion: A rotation flap based on arteries around the ear can be used for coverage of a difficult lesion in the central forehead. Level of evidence: Level V, therapeutic study

  8. The slant of the forehead as a craniofacial feature of impulsiveness

    Directory of Open Access Journals (Sweden)

    J. David Guerrero-Apolo

    2018-03-01

    Full Text Available Objective: Impulsiveness has been the subject of much research, but little is known about the possible relationship between craniofacial anatomy and impulsiveness. The present study was designed to investigate the relationship between one aspect of craniofacial structure (the angle of inclination of the forehead and impulsiveness. Method: Photographs in profile were obtained from 131 volunteers who had been fined for driving at high speed and were undergoing a court-mandated driving license point-recovery course. They completed the Barratt Impulsiveness Scale (BIS-11, the Impulsive Behavior Scale (UPPS-P, and Zuckerman’s Sensation Seeking Scale (V. The angle of the slant of the forehead was measured with a photographic support and a protractor. Results: High positive concordance was found between forehead inclination and 14 out of the 15 impulsiveness factors studied. Conclusions: The angle of inclination of the forehead was significantly associated with self-reported impulsiveness in this sample of traffic violators.

  9. Apparent temperature versus true temperature of silicon crystals as a function of their thickness using infrared measurements

    International Nuclear Information System (INIS)

    Smither, R.K.; Fernandez, P.B.

    1993-01-01

    The very high intensity x-ray beams that will be present at the Advanced Photon Source and other third generation synchrotron sources will require that the first optical element in the beamline and, possibly, the second optical element as well, be cooled to remove the heat deposited by the x-ray beam. In many of the beamlines this heat will be in the 1 to 5 kW range, and any failure of the cooling system will require a quick response from safety control circuits to shut off the beam before damage is done to the optical element. In many cases, this first optical element will be a silicon diffraction crystal. Viewing the surface of objects subjected to high heat fluxes with an infrared camera or infrared sensor has proved to be a very effective method for monitoring the magnitude and distribution of surface temperatures on the object. This approach has been quite useful in studies of cooling silicon crystals in monochromators subject to high heat loads. The main drawback to this method is that single crystals of silicon are partially transparent to the infrared radiation monitored in most infrared cameras. This means that the infrared radiation emitted from the surface contains a component that comes from the interior of the crystal and that the intensity of the emitted radiation and thus the apparent temperature of the surface of the crystal depends on the thickness of the crystal and the kind of coating on the back (and/or the front) of the crystal. The apparent temperature of the crystal increases as the crystal is made thicker. A series of experiments were performed at Argonne National Laboratory to calibrate the apparent surface temperature of the crystal as measured with an infrared camera as a function of the crystal thickness and the type of coating (if any) on the back side of the crystal. A number of examples are given for data taken in synchrotron experiments with high intensity x-ray beams

  10. The Mobility Enhancement of Indium Gallium Zinc Oxide Transistors via Low-temperature Crystallization using a Tantalum Catalytic Layer

    OpenAIRE

    Shin, Yeonwoo; Kim, Sang Tae; Kim, Kuntae; Kim, Mi Young; Oh, Saeroonter; Jeong, Jae Kyeong

    2017-01-01

    High-mobility indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) are achieved through low-temperature crystallization enabled via a reaction with a transition metal catalytic layer. For conventional amorphous IGZO TFTs, the active layer crystallizes at thermal annealing temperatures of 600??C or higher, which is not suitable for displays using a glass substrate. The crystallization temperature is reduced when in contact with a Ta layer, where partial crystallization at the IGZO bac...

  11. Artificial crystals with 3d metal and palladium particles subjected to high-temperature heat treatment

    Science.gov (United States)

    Rinkevich, A. B.; Nemytova, O. V.; Perov, D. V.; Samoylovich, M. I.; Kuznetsov, E. A.

    2018-04-01

    High-temperature heat treatment has valuable impact on the structure and physical properties of artificial crystals with 3d metal and palladium particles. Artificial crystals are obtained by means of introduction of particles into the interspherical voids of opal matrices. The magnetic properties are studied at the temperatures ranging from 2 to 300 K and in fields up to 350 kOe. Microwave properties are investigated in the millimeter frequency range. The complex dielectric permittivity of several nanocomposites is measured. The influence of heat treatment up to 960 °C on the structure of artificial crystals is clarified.

  12. Ice crystal growth under the presence of krypton and methane at low temperature

    Science.gov (United States)

    Kawauchi, Taizo; Yoda, Yoshitaka; Fukutani, Katsuyuki

    2018-02-01

    To investigate the influence of foreign gas inclusion on the crystallization of ice, we studied the low-temperature (74 0.2) of Kr and CH4 enhance the formation of ice Ih and increase the crystal size, while at high foreign gas contents (R ⩽ 0.2) that may develop Kr or CH4 crystals below 92 K, the crystal size and relative amount of ice decrease strongly. The maximum ice Ih crystal size in the order of 200 nm was observed with either Kr or CH4 at 92 K for R = 0.2. We propose that Kr and CH4 induce the crystallization of ice by acting as a surfactant.

  13. Hydrothermal crystallization of amorphous titania films deposited using low temperature atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, D.R.G. [Institute of Materials Engineering, ANSTO, PMB 1, Menai, NSW 2234 (Australia)], E-mail: drm@ansto.gov.au; Triani, G.; Zhang, Z. [Institute of Materials Engineering, ANSTO, PMB 1, Menai, NSW 2234 (Australia)

    2008-10-01

    A two stage process (atomic layer deposition, followed by hydrothermal treatment) for producing crystalline titania thin films at temperatures compatible with polymeric substrates (< 130 deg. C) has been assessed. Titania thin films were deposited at 80 deg. C using atomic layer deposition. They were extremely flat, uniform and almost entirely amorphous. They also contained relatively high levels of residual Cl from the precursor. After hydrothermal treatment at 120 deg. C for 1 day, > 50% of the film had crystallized. Crystallization was complete after 10 days of hydrothermal treatment. Crystallization of the film resulted in the formation of coarse grained anatase. Residual Cl was completely expelled from the film upon crystallization. As a result of the amorphous to crystalline transformation voids formed at the crystallization front. Inward and lateral crystal growth resulted in voids being localized to the film/substrate interface and crystallite perimeters resulting in pinholing. Both these phenomena resulted in films with poor adhesion and film integrity was severely compromised.

  14. Determination of the Temperature Dependence of Heat Capacity for Some Molecular Crystals of Nitro Compounds

    Science.gov (United States)

    Kovalev, Yu. M.; Kuropatenko, V. F.

    2018-05-01

    An analysis of the existing approximations used for describing the dependence of heat capacity at a constant volume on the temperature of a molecular crystal has been carried out. It is shown that the considered Debye and Einstein approximations do not enable one to adequately describe the dependence of heat capacity at a constant volume on the temperature of the molecular crystals of nitro compounds. This inference requires the development of special approximations that would describe both low-frequency and high-frequency parts of the vibrational spectra of molecular crystals. This work presents a universal dependence allowing one to describe the dependence of heat capacity at a constant volume on temperature for a number of molecular crystals of nitro compounds.

  15. Deformation, Stress Relaxation, and Crystallization of Lithium Silicate Glass Fibers Below the Glass Transition Temperature

    Science.gov (United States)

    Ray, Chandra S.; Brow, Richard K.; Kim, Cheol W.; Reis, Signo T.

    2004-01-01

    The deformation and crystallization of Li(sub 2)O (center dot) 2SiO2 and Li(sub 2)O (center dot) 1.6SiO2 glass fibers subjected to a bending stress were measured as a function of time over the temperature range -50 to -150 C below the glass transition temperature (Tg). The glass fibers can be permanently deformed at temperatures about 100 C below T (sub)g, and they crystallize significantly at temperatures close to, but below T,, about 150 C lower than the onset temperature for crystallization for these glasses in the no-stress condition. The crystallization was found to occur only on the surface of the glass fibers with no detectable difference in the extent of crystallization in tensile and compressive stress regions. The relaxation mechanism for fiber deformation can be best described by a stretched exponential (Kohlrausch-Williams-Watt (KWW) approximation), rather than a single exponential model.The activation energy for stress relaxation, Es, for the glass fibers ranges between 175 and 195 kJ/mol, which is considerably smaller than the activation energy for viscous flow, E, (about 400 kJ/mol) near T, for these glasses at normal, stress-free condition. It is suspected that a viscosity relaxation mechanism could be responsible for permanent deformation and crystallization of the glass fibers below T,

  16. High-quality bulk hybrid perovskite single crystals within minutes by inverse temperature crystallization

    KAUST Repository

    Saidaminov, Makhsud I.; Abdelhady, Ahmed L.; Banavoth, Murali; Alarousu, Erkki; Burlakov, Victor M.; Peng, Wei; Dursun, Ibrahim; Wang, Lingfei; He, Yao; Maculan, Giacomo; Goriely, Alain; Wu, Tao; Mohammed, Omar F.; Bakr, Osman

    2015-01-01

    Single crystals of methylammonium lead trihalide perovskites (MAPbX3; MA=CH3NH3+, X=Br− or I−) have shown remarkably low trap density and charge transport properties; however, growth of such high-quality semiconductors is a time-consuming process

  17. Melting temperature evolution of non-reorganized crystals. Poly(3-hydroxybutyrate)

    International Nuclear Information System (INIS)

    Righetti, Maria Cristina; Di Lorenzo, Maria Laura

    2011-01-01

    In the present study the correlation between the melting behaviour of poly(3-hydroxybutyrate) (PHB) original, non-reorganized crystals and the crystallinity increase during isothermal crystallization is presented and discussed. Since the reorganization processes modify the melting curve of original crystals, it is necessary to prevent and hinder all the processes that influence and increase the lamellar thickness. PHB exhibits melting/recrystallization on heating, the occurring of lamellar thickening in the solid state being excluded. The first step of the study was the identification of the scanning rate which inhibits PHB recrystallization at sufficiently high T c . For the extrapolated onset and peak temperatures of the main melting endotherm, which is connected to fusion of dominant lamellae, a double dependence on the crystallization time was found. The crystallization time at which T onset and T peak change their trends was found to correspond to the spherulite impingement time, so that the two different dependencies were put in relation with primary and secondary crystallizations respectively. The increase of both T onset and T peak at high crystallization times after spherulite impingement was considered an effect due to crystal superheating and an indication of a stabilization process of the crystalline phase. Such stabilization, which produces an increase of the melting temperature, is probably connected with the volume filling that occurs after spherulite impingement.

  18. Influence of temperature upon dislocation mobility and elastic limit of single crystal HgI2

    International Nuclear Information System (INIS)

    Milstein, F.; Farber, B.; Kim, K.; van den Berg, L.; Schnepple, W.

    1982-01-01

    The practical importance of studying mechanical properties and dislocation structure of HgI 2 is reviewed briefly. Specifically, the performance of single crystal HgI 2 radiation detectors is evidently sensitive to crystalline imperfections; the dislocation structure, in turn, can be altered during detector fabrication, depending upon the mechanical properties of the crystal and the stresses to which the crystal is subjected. The influence of temperature upon dislocation mobility and plasticity in vapor-grown crystals of mercuric iodide is examined. Dislocation mobiity is determined by measuring the lengths of the longest arms of dislocation etch pit rosettes on (001) surfaces following microhardness indentation and chemical etch. Measurements were made in the range from room temperature to the phase transition temperature of 127 0 C. Dislocation mobility was found to be an increasing function of temperature, with the effect accelerating as the phase transition is approached. Increasing temperature was also found to lower the critical resolved shear stress for plastic deformation on slip on (001) planes. In these contexts, the vapor-grown crystals are clearly softer at their elevated growth temperatures. The results are discussed in terms of a dislocation model involving soft and hard glide dislocations

  19. Single crystal NMR studies of high temperature superconductors

    International Nuclear Information System (INIS)

    Pennington, C.H.; Durand, D.J.; Zax, D.B.; Slichter, C.P.; Rice, J.P.; Bukowski, E.D.; Ginsberg, D.M.

    1989-01-01

    The authors report Cu NMR studies in the normal state of a single crystal of the T/sub c/ = 90 K superconductor YBa 2 Cu 3 O/sub 7/minus/δ/. The authors have measured the magnetic shift tensor, the electric field gradient tensor, the nuclear spin-lattice relaxation rate tensor, and the time dependence and functional form of the transverse decay. From these data they obtain information about the charge state and magnetic state of the Cu atoms, and the existence and size of the electronic exchange coupling between spins of adjacent Cu atoms. 18 refs., 3 figs., 2 tabs

  20. The facile and low temperature synthesis of nanophase hydroxyapatite crystals using wet chemistry

    International Nuclear Information System (INIS)

    Dhand, Vivek; Rhee, K.Y.; Park, Soo-Jin

    2014-01-01

    A simple and facile wet chemistry route was used to synthesize nanophase hydroxyapatite (HaP) crystals at low temperature. The synthesis was carried out at a pH of 11.0 and at a temperature of 37 °C. The resulting samples were washed several times and subjected to further analysis. XRD studies revealed that the HaP crystals were polycrystalline in nature with a crystallite size of ∼ 15–60 ± 5 nm. SEM-EDXA images confirmed the presence of calcium (Ca), phosphorous (P), and oxygen (O) peaks. Likewise, FTIR confirmed the presence of characteristic phosphate and hydroxyl peaks in samples. Lastly, HRTEM images clearly showed distinctive lattice fringes positioned in the 100 and 002 planes. TGA analysis shows that HaP crystals can withstand higher calcination temperatures and are thermally stable. - Highlights: • Facile and low temperature nanophase HaP crystals synthesized at pH 11 and 37 °C • Electron microscopy image of HaP shows characteristic rice grain like morphology. • FTIR results show the characteristic and fingerprint functional groups of HaP. • Thermal stability of HaP crystals up to 500 °C • Growth of Hap crystals occur parallel to c-axis and a possible mechanism proposed

  1. Molecular relaxation behavior and isothermal crystallization above glass transition temperature of amorphous hesperetin.

    Science.gov (United States)

    Shete, Ganesh; Khomane, Kailas S; Bansal, Arvind Kumar

    2014-01-01

    The purpose of this paper was to investigate the relaxation behavior of amorphous hesperetin (HRN), using dielectric spectroscopy, and assessment of its crystallization kinetics above glass transition temperature (Tg ). Amorphous HRN exhibited both local (β-) and global (α-) relaxations. β-Relaxation was observed below Tg , whereas α-relaxation prominently emerged above Tg . β-Relaxation was found to be of Johari-Goldstein type and was correlated with α-process by coupling model. Secondly, isothermal crystallization experiments were performed at 363 K (Tg + 16.5 K), 373 K (Tg + 26.5 K), and 383 K (Tg + 36.5 K). The kinetics of crystallization, obtained from the normalized dielectric strength, was modeled using the Avrami model. Havriliak-Negami (HN) shape parameters, αHN and αHN .βHN , were analyzed during the course of crystallization to understand the dynamics of amorphous phase during the emergence of crystallites. HN shape parameters indicated that long range (α-like) were motions affected to a greater extent than short range (β-like) motions during isothermal crystallization studies at all temperature conditions. The variable behavior of α-like motions at different isothermal crystallization temperatures was attributed to evolving crystallites with time and increase in electrical conductivity with temperature. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

  2. Relation between the concentration of defects and the temperature on a crystal

    Energy Technology Data Exchange (ETDEWEB)

    Adorno, A T.V.; Cilense, M [UNESP, Araraquara (Brazil). Inst. de Quimica; Garlipp, W [Sao Paulo Univ., Sao Carlos (Brazil). Escola de Engenharia

    1982-01-01

    Following the basic thermodynamics principles, the relation between the concentration of defects and the temperature on a crystal was established. In the case of vacancies, the relation between the changes in the resistivity and the absolute quench temperature was also obtained.

  3. The temperature gradient on section of casting in process of primary crystallization of chromium cast iron

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2008-08-01

    Full Text Available The methodology of defining in article was introduced the temperature gradient in process of primary crystallization during cooling the casting from chromium cast iron on basis of measurements of thermal field in test DTA-K3. Insert also the preliminary results of investigations of influence temperature gradient on structure of studied wear resistance chromium cast iron.

  4. Neutron scattering experiments of the ionic crystal deformed plastically with uniaxial compression under high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Yoshinori; Minakawa, Nobuaki; Aizawa, Kazuya; Ozawa, Kunio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1996-04-01

    As an aim of huge growth of alkali halide (AH) single crystal, a mosaic structure of small size AH single crystal deformed plastically with uniaxial compression under high temperature was evaluated due to its neutron irradiation experiment. Using TAS-2 installed at JRR-3M guide hole of Japan Atomic Energy Research Institute, locking curve at a representative face factor of the specimen was measured to observe the mosaic structure accompanied with expansion of the crystal due to compression. As a result, though the specimen before compression could be supposed to be divided to some parts already, the locking curve under 10 sec. of compression time showed already some fracture to divisions to suppose finer degradation of the crystal, and division of the locking curve at 600 sec. of compression time could be observed onto its 220 face. And, every compressed specimens showed some changes of crystallization method from standard sample. (G.K.)

  5. Utilization of High-Temperature Slags From Metallurgy Based on Crystallization Behaviors

    Science.gov (United States)

    Sun, Yongqi; Zhang, Zuotai

    2018-05-01

    Here, following the principle of modifying crystallization behaviors, including avoidance and optimization, we review recent research on the utilization of hot slags. Because of the high-temperature property (1450-1650°C), the utilization of hot slags are much different from that of other wastes. We approach this issue from two main directions, namely, material recycling and heat utilization. From the respect of material recycling, the utilization of slags mainly follows total utilization and partial utilization, whereas the heat recovery from slags follows two main paths, namely, physical granulation and chemical reaction. The effective disposal of hot slags greatly depends on clarifying the crystallization behaviors, and thus, we discuss some optical techniques and their applicable scientific insights. For the purpose of crystallization avoidance, characterizing the glass-forming ability of slags is of great significance, whereas for crystallization modification, the selection of chemical additives and control of crystallization conditions comprise the central routes.

  6. Creep of crystals: High-temperature deformation processes in metals, ceramics and minerals

    Science.gov (United States)

    Poirier, J. P.

    An introductory text describing high-temperature deformation processes in metals, ceramics, and minerals is presented. Among the specific topics discussed are: the mechanical aspects of crystal deformation; lattice defects; and phenomenological and thermodynamical analysis of quasi-steady-state creep. Consideration is also given to: dislocation creep models; the effect of hydrostatic pressure on deformation; creep polygonization; and dynamic recrystallization. The status of experimental techniques for the study of transformation plasticity in crystals is also discussed.

  7. Nanostructure characterization of beta-sheet crystals in silk under various temperatures

    Directory of Open Access Journals (Sweden)

    Zhang Yan

    2014-01-01

    Full Text Available This paper studies the nanostructure characterizations of β-sheet in silk fiber with different reaction temperatures. A molecular dynamic model is developed and simulated by Gromacs software packages. The results reveal the change rules of the number of hydrogen bonds in β-sheet under different temperatures. The best reaction temperature for the β-sheet crystals is also found. This work provides theoretical basis for the designing of materials based on silk.

  8. Temperature-Frequency Converter Using a Liquid Crystal Cell as a Sensing Element

    Directory of Open Access Journals (Sweden)

    José Isidro Santos

    2012-03-01

    Full Text Available A new temperature-frequency converter based on the variation of the dielectric permittivity of the Liquid Crystal (LC material with temperature has been demonstrated. Unlike other temperature sensors based on liquid crystal processing optical signals for determining the temperature, this work presents a system that is able to sense temperature by using only electrical signals. The variation of the dielectric permittivity with temperature is used to modify the capacitance of a plain capacitor using a LC material as non-ideal dielectric. An electric oscillator with an output frequency depending on variable capacitance made of a twisted-nematic (TN liquid crystal (LC cell has been built. The output frequency is related to the temperature of LC cell through the equations associated to the oscillator circuit. The experimental results show excellent temperature sensitivity, with a variation of 0.40% of the initial frequency per degree Celsius in the temperature range from −6 °C to 110 °C.

  9. Temperature fluctuations in a LiNbO 3 melt during crystal growth

    Science.gov (United States)

    Suzuki, Tetsuro

    2004-10-01

    Variations in temperature induced by forced convection on the surface of a LiNbO3 melt during crystal growth have been studied. Temperature measurements on the melt surface of single crystals growing (∅ 50 mm) at rotation rates of 15-40 rpm on an RF-heated Czochralski puller has revealed that the melt surface continuously alternates between a steady and unsteady state of flow. This was attributed to the intermittently turbulent flow mode at intermediate rotation rates. The fluctuation period is thought to depend on the thickness of its boundary layer. The boundary layer varies in thickness due to the melt flow, which stops as the interface moves toward the crystal and resumes once the interface reverts to its former position. By contrast, at above 60 rpm, the melt surface temperature drops without fluctuation, indicating that turbulent flow is dominant at faster rotation rates.

  10. Effects of heat treatment temperature on morphology and properties of opal crystal

    International Nuclear Information System (INIS)

    Duan Tao; China Academy of Engineering Physics, Mianyang; Peng Tongjiang; Chen Jiming; Tang Yongjian

    2008-01-01

    The monodispersed SiO 2 microspheres were synthesized by reactant mixed equally. The colloid crystal templates were assemblied by vertical sedimentation method in ethanol at certain temperatures, and the effects of the heat treatment temperature on the morphology and the properties of opal colloid crystals were investigated. SEM, TCr-DSC results indicate SiO 2 colloid templates should be heat treated at 700-800 degree C, enhancing the conglutination and mechanistic intensity of opal templates. UV-Vis analysis result indicates that the heat treatment process can remove the photonic band gap location of the opal colloid crystals, and with the heat treatment temperature increasing gradually, blue shift occurs and the gap narrows. (authors)

  11. Characterization of Anodic Aluminum Oxide Membrane with Variation of Crystallizing Temperature for pH Sensor.

    Science.gov (United States)

    Yeo, Jin-Ho; Lee, Sung-Gap; Jo, Ye-Won; Jung, Hye-Rin

    2015-11-01

    We fabricated electrolyte-dielectric-metal (EDM) device incorporating a high-k Al2O3 sensing membrane from a porous anodic aluminum oxide (AAO) using a two step anodizing process for pH sensors. In order to change the properties of the AAO template, the crystallizing temperature was varied from 400 degrees C to 700 degrees C over 2 hours. The structural properties were observed by field emission scanning electron microscopy (FE-SEM). The pH sensitivity increased with an increase in the crystallizing temperature from 400 degrees C to 600 degrees C. However at 700 degrees C, deformation occurred. The porous AAO sensor with a crystallizing temperature of 600 degrees C displayed the good sensitivity and long-term stability and the values were 55.7 mV/pH and 0.16 mV/h, respectively.

  12. Defect-induced local variation of crystal phase transition temperature in metal-halide perovskites.

    Science.gov (United States)

    Dobrovolsky, Alexander; Merdasa, Aboma; Unger, Eva L; Yartsev, Arkady; Scheblykin, Ivan G

    2017-06-26

    Solution-processed organometal halide perovskites are hybrid crystalline semiconductors highly interesting for low-cost and efficient optoelectronics. Their properties are dependent on the crystal structure. Literature shows a variety of crystal phase transition temperatures and often a spread of the transition over tens of degrees Kelvin. We explain this inconsistency by demonstrating that the temperature of the tetragonal-to-orthorhombic phase transition in methylammonium lead triiodide depends on the concentration and nature of local defects. Phase transition in individual nanowires was studied by photoluminescence microspectroscopy and super-resolution imaging. We propose that upon cooling from 160 to 140 K, domains of the crystal containing fewer defects stay in the tetragonal phase longer than highly defected domains that readily transform to the high bandgap orthorhombic phase at higher temperatures. The existence of relatively pure tetragonal domains during the phase transition leads to drastic photoluminescence enhancement, which is inhomogeneously distributed across perovskite microcrystals.Understanding crystal phase transition in materials is of fundamental importance. Using luminescence spectroscopy and super-resolution imaging, Dobrovolsky et al. study the transition from the tetragonal to orthorhombic crystal phase in methylammonium lead triiodide nanowires at low temperature.

  13. Development of a CE-QUAL-W2 temperature model for Crystal Springs Lake, Portland, Oregon

    Science.gov (United States)

    Buccola, Norman L.; Stonewall, Adam J.

    2016-05-19

    During summer 2014, lake level, streamflow, and water temperature in and around Crystal Springs Lake in Portland, Oregon, were measured by the U.S. Geological Survey and the City of Portland Bureau of Environmental Services to better understand the effect of the lake on Crystal Springs Creek and Johnson Creek downstream. Johnson Creek is listed as an impaired water body for temperature by the Oregon Department of Environmental Quality (ODEQ), as required by section 303(d) of the Clean Water Act. A temperature total maximum daily load applies to all streams in the Johnson Creek watershed, including Crystal Springs Creek. Summer water temperatures downstream of Crystal Springs Lake and the Golf Pond regularly exceed the ODEQ numeric criterion of 64.4 °F (18.0 °C) for salmonid rearing and migration. To better understand temperature contributions of this system, the U.S. Geological Survey developed two-dimensional hydrodynamic water temperature models of Crystal Springs Lake and the Golf Pond. Model grids were developed to closely resemble the bathymetry of the lake and pond using data from a 2014 survey. The calibrated models simulated surface water elevations to within 0.06 foot (0.02 meter) and outflow water temperature to within 1.08 °F (0.60 °C). Streamflow, water temperature, and lake elevation data collected during summer 2014 supplied the boundary and reference conditions for the model. Measured discrepancies between outflow and inflow from the lake, assumed to be mostly from unknown and diffuse springs under the lake, accounted for about 46 percent of the total inflow to the lake.

  14. High temperature oxidation and crystallization behavior of phosphate glass compositions

    International Nuclear Information System (INIS)

    Russo, Diego; Rodriguez, Diego; Grumbaum, N.; Gonzalez Oliver, Carlos

    2003-01-01

    We analyzed the thermal transformation of three iron phosphate glasses having the following nominal compositions: M4 [70% P 2 O 5 , 30% Fe 2 O 3 ], M5 [85% M4, 15% UO 2 ] y M7 [69.7% P 2 O 5 , 28.6% Fe 2 O 3 , 1,7% Al 2 O 3 ]. Thermogravimetric analysis, DTA (differential thermal analysis) and SAXS (Small Angle X-ray Scattering) were performed.It was observed that it is easily possible to produce glasses in these systems having very low crystallinity.We could determine the final stable crystalline phases [Fe 4 (P 2 O 7 ) 3 , Fe(PO 3 ) 3 and Fe 3 (P 2 O 7 ) 2 ].The presence of uranium ions affects not only the redox effects but also the crystallization of the system.SAXS data obtained during the heating in vacuum up to ∼600degC, gave some variation of scattering intensities vs. scattering vector suggesting the development of an extra phase or some kind inhomogeneities that seems to disappear on heating

  15. Room temperature exchange bias in SmFeO_3 single crystal

    International Nuclear Information System (INIS)

    Wang, Xiaoxiong; Cheng, Xiangyi; Gao, Shang; Song, Junda; Ruan, Keqing; Li, Xiaoguang

    2016-01-01

    Exchange bias phenomenon is generally ascribed to the unidirectional magnetic shift along the field axes at interface of two magnetic materials. Room temperature exchange bias is found in SmFeO_3 single crystal. The behavior after different cooling procedure is regular, and the training behavior is attributed to the athermal training and its pinning origin is attributed to the antiferromagnetic clusters. Its being single phase and occurring at room temperature make it an appropriate candidate for application. - Graphical abstract: Room temperature exchange bias was found in oxide single crystal. Highlights: • Room temperature exchange bias has been discovered in single-crystalline SmFeO_3. • Its pinning origin is attributed to the antiferromagnetic clusters. • Its being single phase and occurring at room temperature make it an appropriate candidate for application.

  16. Intracrystalline oxygen isotope effects in CuSO4.5H2O and their dependence on crystallization temperature

    International Nuclear Information System (INIS)

    Heinzinger, K.

    1976-01-01

    In copper sulphate pentahydrate the water molecules occupy three different sites, connected with different oxygen isotope ratios. Results of measurements of the change of these isotope ratios with crystallization temperature are reported. The temperature dependence found here provides the basis for the determination of crystallization temperatures of hydrated crystals from such intracrystalline oxygen isotope fractionation. Suppositions necessary for the application of this method are discussed. (author)

  17. Defect types and room-temperature ferromagnetism in undoped rutile TiO2 single crystals

    Science.gov (United States)

    Li, Dong-Xiang; Qin, Xiu-Bo; Zheng, Li-Rong; Li, Yu-Xiao; Cao, Xing-Zhong; Li, Zhuo-Xin; Yang, Jing; Wang, Bao-Yi

    2013-03-01

    Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO2 single crystals when a magnetic field is applied parallel to the sample plane. By combining X-ray absorption near the edge structure spectrum and positron annihilation lifetime spectroscopy, Ti3+—VO defect complexes (or clusters) have been identified in annealed crystals at a high vacuum. We elucidate that the unpaired 3d electrons in Ti3+ ions provide the observed room-temperature ferromagnetism. In addition, excess oxygen ions in the TiO2 lattice could induce a number of Ti vacancies which obviously increase magnetic moments.

  18. Defect types and room-temperature ferromagnetism in undoped rutile TiO2 single crystals

    International Nuclear Information System (INIS)

    Li Dong-Xiang; Cao Xing-Zhong; Li Zhuo-Xin; Yang Jing; Wang Bao-Yi; Qin Xiu-Bo; Zheng Li-Rong; Li Yu-Xiao

    2013-01-01

    Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO 2 single crystals when a magnetic field is applied parallel to the sample plane. By combining X-ray absorption near the edge structure spectrum and positron annihilation lifetime spectroscopy, Ti 3+ —V O defect complexes (or clusters) have been identified in annealed crystals at a high vacuum. We elucidate that the unpaired 3d electrons in Ti 3+ ions provide the observed room-temperature ferromagnetism. In addition, excess oxygen ions in the TiO 2 lattice could induce a number of Ti vacancies which obviously increase magnetic moments

  19. Dramatic improvement of crystal quality for low-­temperature-grown rabbit muscle aldolase

    Science.gov (United States)

    Park, HaJeung; Rangarajan, Erumbi S.; Sygusch, Jurgen; Izard, Tina

    2010-01-01

    Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA–LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice. PMID:20445268

  20. Dramatic Improvement of Crystal Quality for Low-temperature-grown Rabbit Muscle Aldolase

    Energy Technology Data Exchange (ETDEWEB)

    Park, H.; Rangarajan, E; Sygusch, J; Izard, T

    2010-01-01

    Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA-LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 {angstrom} Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA-LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice.

  1. Dramatic improvement of crystal quality for low-temperature-grown rabbit muscle aldolase.

    Science.gov (United States)

    Park, Hajeung; Rangarajan, Erumbi S; Sygusch, Jurgen; Izard, Tina

    2010-05-01

    Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA-LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 A Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA-LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice.

  2. Effect of the Cu and Ni content on the crystallization temperature and crystallization mechanism of La–Al–Cu(Ni metallic glasses

    Directory of Open Access Journals (Sweden)

    Peiyou Li

    2016-02-01

    Full Text Available The effect of the Cu and Ni content on the crystallization mechanism and the crystallization temperatures of La–Al–Cu(Ni metallic glasses (MGs was studied by differential scanning calorimetry (DSC. The experimental results have shown that the DSC curves obtained for the La–Al–Cu and La–Al–Ni MGs exhibit two and three crystallization temperatures, respectively. The crystallization temperatures of the La–Al–Cu and La–Al–Ni MGs result from the merging and splitting of thermal events related to the corresponding eutectic atomic pairs in the La72Cu28 and La81.6Al18.4 MGs, and La72Ni28 and La81.6Al18.4 MGs, respectively. In addition, Al- and Ni-containing clusters with weak or strong atomic interaction in the Al–Ni atomic pairs strongly affect the crystallization mechanism and thus the crystallization temperature of La–Al–Ni MGs. This study provides a novel understanding of the relation between the crystallization temperature and the underlying crystallization mechanisms in La–Al–Cu(Ni MGs.

  3. Forehead Augmentation with a Methyl Methacrylate Onlay Implant Using an Injection-Molding Technique

    Directory of Open Access Journals (Sweden)

    Dong Kwon Park

    2013-09-01

    Full Text Available Background The forehead, which occupies about one third of the face, is one of the majordeterminants of a feminine or masculine look. Various methods have been used for the augmentationof the forehead using autologous fat grafts or alloplastic materials. Methylmethacrylate(MMA is the most appropriate material for augmentation of the forehead, and we have usedan injection-molding technique with MMA to achieve satisfactory results.Methods Under local anesthesia with intravenous (IV sedation, an incision was made onthe scalp and a meticulous and delicate subperiosteal dissection was then performed. MMAmonomers and polymers were mixed, the dough was injected into the space created, andmanual molding was performed along with direct inspection. This surgery was indicated forpatients who wanted to correct an unattractive appearance by forehead augmentation. Everypatient in this study visited our clinics 3 months after surgery to evaluate the results. Wejudged the postoperative results in terms of re-operation rates caused by the dissatisfactionof the patients and complications.Results During a 13-year period, 516 patients underwent forehead augmentation with MMA.With the injection-molding technique, the inner surface of the MMA implant is positionedclose to the underlying frontal bone, which minimizes the gap between the implant and bone.The borders of the implant should be tapered sufficiently until no longer palpable or visible.Only 28 patients (5.4% underwent a re-operation due to an undesirable postoperative appearance.Conclusions The injection-molding technique using MMA is a simple, safe, and ideal methodfor the augmentation of the forehead.

  4. Forehead Augmentation with a Methyl Methacrylate Onlay Implant Using an Injection-Molding Technique

    Directory of Open Access Journals (Sweden)

    Dong Kwon Park

    2013-09-01

    Full Text Available BackgroundThe forehead, which occupies about one third of the face, is one of the major determinants of a feminine or masculine look. Various methods have been used for the augmentation of the forehead using autologous fat grafts or alloplastic materials. Methylmethacrylate (MMA is the most appropriate material for augmentation of the forehead, and we have used an injection-molding technique with MMA to achieve satisfactory results.MethodsUnder local anesthesia with intravenous (IV sedation, an incision was made on the scalp and a meticulous and delicate subperiosteal dissection was then performed. MMA monomers and polymers were mixed, the dough was injected into the space created, and manual molding was performed along with direct inspection. This surgery was indicated for patients who wanted to correct an unattractive appearance by forehead augmentation. Every patient in this study visited our clinics 3 months after surgery to evaluate the results. We judged the postoperative results in terms of re-operation rates caused by the dissatisfaction of the patients and complications.ResultsDuring a 13-year period, 516 patients underwent forehead augmentation with MMA. With the injection-molding technique, the inner surface of the MMA implant is positioned close to the underlying frontal bone, which minimizes the gap between the implant and bone. The borders of the implant should be tapered sufficiently until no longer palpable or visible. Only 28 patients (5.4% underwent a re-operation due to an undesirable postoperative appearance.ConclusionsThe injection-molding technique using MMA is a simple, safe, and ideal method for the augmentation of the forehead.

  5. Extension of an anisotropic creep model to general high temperature deformation of a single crystal superalloy

    International Nuclear Information System (INIS)

    Pan, L.M.; Ghosh, R.N.; McLean, M.

    1993-01-01

    A physics based model has been developed that accounts for the principal features of anisotropic creep deformation of single crystal superalloys. The present paper extends this model to simulate other types of high temperature deformation under strain controlled test conditions, such as stress relaxation and tension tests at constant strain rate in single crystals subject to axial loading along an arbitrary crystal direction. The approach is applied to the SRR99 single crystal superalloy where a model parameter database is available, determined via analysis of a database of constant stress creep curves. A software package has been generated to simulate the deformation behaviour under complex stress-strain conditions taking into account anisotropic elasticity. (orig.)

  6. Investigation of melt structure and crystallization processes by high-temperature Raman spectroscopy method

    International Nuclear Information System (INIS)

    Voron'ko, Yu.K.; Kudryavtsev, A.B.; Osiko, V.V.; Sobol', A.A.

    1988-01-01

    A review of studies dealing with the melts of alkali, rare earth and other element phosphates, gallates, germanates, niobates and tungstates, which are carried out by the method of high-temperature Raman spectroscopy, is given. The effect of the melt structure on the mechanism of the substance cystallization is considered. It is shown that vitrification and supercooling of the melt, as well as its crystallization in the from of metastable structures, are related to the effect of nonconformity between the melt and crystal strucure. The effect of nonconformity between anion motives in the melt and crystal creates obstacles for equilibrium structure nucleation, which results in the formation mainly of metastable forms with lattice structure for from the structure of the melt, though cases of equilibrium phase crystallization are also possible. 37 refs.; 13 figs.; 2 tabs

  7. Primary crystallization in Al-rich metallic glasses at unusually low temperatures

    International Nuclear Information System (INIS)

    Bokeloh, J.; Boucharat, N.; Roesner, H.; Wilde, G.

    2010-01-01

    The initial stage of the primary crystallization reaction and the glass transition of the marginal metallic glass Al 89 Y 6 Fe 5 were investigated by conventional differential scanning calorimetry (DSC) and modulated differential scanning calorimetry (MDSC), microcalorimetry, X-ray diffraction (XRD) and transmission electron microscopy. A sharp onset of the primary crystallization was found by microcalorimetry and XRD studies at temperatures which were 120 deg. C below the primary crystallization peak observed in conventional DSC. A systematic MDSC study of annealed samples revealed a wide spectrum of glass transition onsets, which show a strong dependence on the annealing conditions. In addition, the glass transition onsets can be linked to the initial stage of the primary crystallization. The spectrum of glass transition onsets observed is discussed with respect to the occurrence of phase separation preceding the nucleation and growth of dendritic aluminium nanocrystals.

  8. Calibration of the apparent temperature of silicon single crystals as a function of their true temperature and their thickness as determined by infrared measurements

    International Nuclear Information System (INIS)

    Smither, R.K.; Fernandez, P.B.

    1993-09-01

    Viewing the surface of objects subjected to high heat fluxes with an infrared camera or infrared sensor has proved to be a very effective method for monitoring the magnitude and distribution of surface temperature on the object. This approach has been quite useful in studies of cooling silicon crystals in monochromators subject to high heat loads. The main drawback to this method is that single crystals of silicon are partially transparent to the infrared radiation monitored in most infrared cameras. This means that the infrared radiation emitted from the surface contains a component that comes from the interior of the crystal and that the intensity of the emitted radiation and thus the apparent temperature of the surface of the crystal depends on the thickness of the crystal and the kind of coating on the back (and/or the front) of the crystal. The apparent temperature of the crystal increases as the crystal is made thicker. A series of experiments were performed at Argonne National Laboratory to calibrate the apparent surface temperature of the crystal as measured with an infrared camera as a function of the crystal thickness and the type of coating (if any) on the back side of the crystal. A good reflecting surface on the back side of the crystal increases the apparent temperature of the crystal and simulates the response of a crystal twice the thickness. These measurements make it possible to interpret the infrared signals from cooled silicon crystals used in past high heat load experiments. A number of examples are given for data taken in synchrotron experiments with high intensity x-ray beams

  9. Two convenient low-temperature routes to single crystals of plutonium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Meredith, Nathan A. [Departments of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States); Wang, Shuao; Diwu, Juan [School of Radiation Medicine and Protection and School of Radiological and Interdisciplinary Sciences, Soochow University, Suzhou, Jiangsu 215123 (China); Albrecht-Schmitt, Thomas E., E-mail: talbrechtschmitt@gmail.com [Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306 (United States)

    2014-11-15

    Highlights: • Two low-temperature routes to the growth single crystals of plutonium dioxide. • Safer methods of preparing PuO{sub 2} single crystals that do not involve solid-state synthetic techniques. • Solvothermal crystal growth of plutonium dioxide. - Abstract: During the solvothermal synthesis of a low-dimensional borate, KB{sub 5}O{sub 7}(OH){sub 2}⋅2H{sub 2}O, in the presence of Pu(III), single crystals of plutonium dioxide unexpectedly formed. Single crystals of PuO{sub 2} also formed during the hydrothermal synthesis of another borate, Na{sub 2}B{sub 5}O{sub 8}(OH)⋅2H{sub 2}O, in the presence of Pu(III). The reactions were conducted at 170 °C and 150 °C, respectively, which are much lower temperature than previously reported preparations of crystalline PuO{sub 2}. Yellow–green crystals with a tablet habit were characterized by single crystal X-ray diffraction and solid-state UV–vis–NIR absorption spectroscopy. The crystal structure was solved by direct methods with R{sub 1} = 1.26% for 19 unique observed reflections. PuO{sub 2} is cubic, space group Fm3{sup ‾}m, and adopts the fluorite structure type. The lattice parameter was determined to be a = 5.421(5) Å giving a volume of 159.3(2) Å{sup 3}. The absorption spectrum is consistent with Pu(IV)

  10. Surface induces different crystal structures in a room temperature switchable spin crossover compound.

    Science.gov (United States)

    Gentili, Denis; Liscio, Fabiola; Demitri, Nicola; Schäfer, Bernhard; Borgatti, Francesco; Torelli, Piero; Gobaut, Benoit; Panaccione, Giancarlo; Rossi, Giorgio; Degli Esposti, Alessandra; Gazzano, Massimo; Milita, Silvia; Bergenti, Ilaria; Ruani, Giampiero; Šalitroš, Ivan; Ruben, Mario; Cavallini, Massimiliano

    2016-01-07

    We investigated the influence of surfaces in the formation of different crystal structures of a spin crossover compound, namely [Fe(L)2] (LH: (2-(pyrazol-1-yl)-6-(1H-tetrazol-5-yl)pyridine), which is a neutral compound thermally switchable around room temperature. We observed that the surface induces the formation of two different crystal structures, which exhibit opposite spin transitions, i.e. on heating them up to the transition temperature, one polymorph switches from high spin to low spin and the second polymorph switches irreversibly from low spin to high spin. We attributed this inversion to the presence of water molecules H-bonded to the complex tetrazolyl moieties in the crystals. Thin deposits were investigated by means of polarized optical microscopy, atomic force microscopy, X-ray diffraction, X-ray absorption spectroscopy and micro Raman spectroscopy; moreover the analysis of the Raman spectra and the interpretation of spin inversion were supported by DFT calculations.

  11. Low-Temperature Crystal Structures of the Hard Core Square Shoulder Model

    Directory of Open Access Journals (Sweden)

    Alexander Gabriëlse

    2017-11-01

    Full Text Available In many cases, the stability of complex structures in colloidal systems is enhanced by a competition between different length scales. Inspired by recent experiments on nanoparticles coated with polymers, we use Monte Carlo simulations to explore the types of crystal structures that can form in a simple hard-core square shoulder model that explicitly incorporates two favored distances between the particles. To this end, we combine Monte Carlo-based crystal structure finding algorithms with free energies obtained using a mean-field cell theory approach, and draw phase diagrams for two different values of the square shoulder width as a function of the density and temperature. Moreover, we map out the zero-temperature phase diagram for a broad range of shoulder widths. Our results show the stability of a rich variety of crystal phases, such as body-centered orthogonal (BCO lattices not previously considered for the square shoulder model.

  12. Low temperature phase of the trigonal RbIn(MoO4)2 crystal

    Science.gov (United States)

    Zapart, W.; Zapart, M. B.; Schranz, W.; Reinecker, M.

    2013-02-01

    The present article is devoted to a new low-temperature phase transition found at about T pt = 84 K in the layered RbIn(MoO4)2 crystal. This phase transition is well proved by dynamical mechanical analysis through anomalies in the temperature behaviour of both real and imaginary parts of the Young's modulus. From the polarizing microscope observations it was found that below T pt the ferroelastic phase disappears. This transition has also been seen through strong changes in the shape of the electron paramagnetic resonance lines. EPR studies, performed in the liquid nitrogen temperature, yield evidence of strong rebuilding of the crystal unit cell in comparison with that of the high temperature paraelastic phase.

  13. Transition Temperatures of Thermotropic Liquid Crystals from the Local Binary Gray Level Cooccurrence Matrix

    Directory of Open Access Journals (Sweden)

    S. Sreehari Sastry

    2012-01-01

    Full Text Available This paper presents a method which combines the statistical analysis with texture structural analysis called Local Binary Gray Level Cooccurrence Matrix (LBGLCM to investigate the phase transition temperatures of thermotropic p,n-alkyloxy benzoic acid (nOBA, n=4,6,8,10 and 12 liquid crystals. Textures of the homeotropically aligned liquid crystal compounds are recorded as a function of temperature using polarizing optical microscope attached to the hot stage and high resolution camera. In this method, second-order statistical parameters (contrast, energy, homogeneity, and correlation are extracted from the LBGLCM of the textures. The changes associatedwiththe values of extracted parameters as a function of temperature are a helpful process to identify the phases and phase transition temperatures of the samples. Results obtained from this method have validity and are in good agreement with the literature.

  14. Temperature dependences of photoconductivity of CdHgTe crystals with photoactive inclusions

    International Nuclear Information System (INIS)

    Vlasenko, A.I.; Vlasenko, Z.K.

    1999-01-01

    Temperature dependences of life time τ and spectral characteristics of photoconductivity for Cd x Hg 1-x Te crystals (x = 0.2) with photoactive inclusions are investigated. It is shown that the N-type character of effective lifetime temperature dependences in nonhomogeneous crystals, in particular, its sharp temperature activation in the region of transition from the impurity to the intrinsic conductivity is determined by not the Shockley-Read mechanism, but by the interband impact mechanism with changing effective geometrical sizes of recombination active regions under temperature increase. Within the frames of this model the smoothing of the non-monotone character of the photoconductivity spectral characteristics in the region of fundamental absorption under the heating is explained. The calculation results that are in qualitative agreement with the experimental data are presented [ru

  15. Frequency and Temperature Dependence of Fabrication Parameters in Polymer Dispersed Liquid Crystal Devices

    Science.gov (United States)

    Torres, Juan C.; Vergaz, Ricardo; Barrios, David; Sánchez-Pena, José Manuel; Viñuales, Ana; Grande, Hans Jürgen; Cabañero, Germán

    2014-01-01

    A series of polymer dispersed liquid crystal devices using glass substrates have been fabricated and investigated focusing on their electrical properties. The devices have been studied in terms of impedance as a function of frequency. An electric equivalent circuit has been proposed, including the influence of the temperature on the elements into it. In addition, a relevant effect of temperature on electrical measurements has been observed. PMID:28788632

  16. Frequency and Temperature Dependence of Fabrication Parameters in Polymer Dispersed Liquid Crystal Devices

    Directory of Open Access Journals (Sweden)

    Juan C. Torres

    2014-05-01

    Full Text Available A series of polymer dispersed liquid crystal devices using glass substrates have been fabricated and investigated focusing on their electrical properties. The devices have been studied in terms of impedance as a function of frequency. An electric equivalent circuit has been proposed, including the influence of the temperature on the elements into it. In addition, a relevant effect of temperature on electrical measurements has been observed.

  17. Variation of low temperature internal friction of microplastic deformation of high purity molybdenum single crystals

    International Nuclear Information System (INIS)

    Pal-Val, P.P.; Kaufmann, H.J.

    1984-01-01

    Amplitude and temperature spectra of ultrasound absorption in weakly deformed high purity molybdenum single crystals of different orientations were measured. The results were discussed in terms of parameter changes related to quasiparticle or dislocation oscillations, respectively, dislocation point defect interactions as well as defect generation at microplastic deformation. (author)

  18. Sensitivity of photonic crystal fiber grating sensors: biosensing, refractive index, strain, and temperature sensing

    DEFF Research Database (Denmark)

    Rindorf, Lars Henning; Bang, Ole

    2008-01-01

    We study the sensitivity of fiber grating sensors in the applications of strain, temperature, internal label-free biosensing, and internal refractive index sensing. New analytical expressions for the sensitivities, valid for photonic crystal fibers are rigorously derived. These are generally vali...

  19. A low-temperature sample orienting device for single crystal spectroscopy at the SNS

    Energy Technology Data Exchange (ETDEWEB)

    Sherline, T E; Solomon, L; Roberts, C K II; Bruce, D; Gaulin, B; Granroth, G E, E-mail: sherlinete@ornl.gov

    2010-11-01

    A low temperature sample orientation device providing three axes of rotation has been successfully built and is in testing for use on several spectrometers at the spallation neutron source (SNS). Sample rotation about the vertical ({omega}) axis of nearly 360 deg. and out of plane tilts ({phi} and v) of from -3.4 deg. to 4.4 deg. and from -2.8 deg. to 3.5 deg., respectively, are possible. An off-the-shelf closed cycle refrigerator (CCR) is mounted on a room temperature sealed rotary flange providing {omega} rotations of the sample. Out-of-plane tilts are made possible by piezoelectric actuated angular positioning devices mounted on the low temperature head of the CCR. Novel encoding devices based on magnetoresistive sensors have been developed to measure the tilt stage angles. This combination facilitates single crystal investigations from room temperature to 3.1 K. Commissioning experiments of the rotating CCR for both powder and single crystal samples have been performed on the ARCS spectrometer at the SNS. For the powder sample this device was used to continuously rotate the sample and thus average out any partial orientation of the powder. The powder rings observed in S(Q) are presented. For the single crystal sample, the rotation was used to probe different regions of momentum transfer (Q-space). Laue patterns obtained from a single crystal sample at two rotation angles are presented.

  20. Crystallization speed of salbutamol as a function of relative humidity and temperature.

    Science.gov (United States)

    Zellnitz, Sarah; Narygina, Olga; Resch, Christian; Schroettner, Hartmuth; Urbanetz, Nora Anne

    2015-07-15

    Spray dried salbutamol sulphate and salbutamol base particles are amorphous as a result of spray drying. As there is always the risk of recrystallization of amorphous material, the aim of this work is the evaluation of the temperature and humidity dependent recrystallization of spray dried salbutamol sulphate and base. Therefore in-situ Powder X-ray Diffraction (PXRD) studies of the crystallization process at various temperature (25 and 35 °C) and humidity (60%, 70%, 80%, 90% relative humidity) conditions were performed. It was shown that the crystallization speed of salbutamol sulphate and base is a non-linear function of both temperature and relative humidity. The higher the relative humidity the higher is the crystallization speed. At 60% relative humidity salbutamol base as well as salbutamol sulphate were found to be amorphous even after 12 h, however samples changed optically. At 70% and 90% RH recrystallization of salbutamol base is completed after 3 h and 30 min and recrystallization of salbutamol sulphate after 4h and 1h, respectively. Higher temperature (35 °C) also leads to increased crystallization speeds at all tested values of relative humidity. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Temperature and composition dependence of birefringence of lithium-tantalate crystals determined by holographic scattering

    International Nuclear Information System (INIS)

    Bastwoeste, K.; Schwalenberg, S.; Baeumer, Ch.; Kraetzig, E.

    2003-01-01

    Iron-doped lithium-tantalate samples with different compositions ranging from the congruently melting to the stoichiometric one are analyzed by anisotropic holographic scattering. The temperature dependence of the birefringence yields information on the composition of the crystals. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Temperature and composition dependence of birefringence of lithium-tantalate crystals determined by holographic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bastwoeste, K.; Schwalenberg, S.; Baeumer, Ch.; Kraetzig, E. [Fachbereich Physik, Universitaet Osnabrueck, D-49069 Osnabrueck (Germany)

    2003-09-01

    Iron-doped lithium-tantalate samples with different compositions ranging from the congruently melting to the stoichiometric one are analyzed by anisotropic holographic scattering. The temperature dependence of the birefringence yields information on the composition of the crystals. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Variation of low temperature internal friction of microplastic deformation of high purity molybdenum single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Pal-Val, P.P. (AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst. Nizkikh Temperatur); Kaufmann, H.J. (Akademie der Wissenschaften der DDR, Berlin)

    1984-08-01

    Amplitude and temperature spectra of ultrasound absorption in weakly deformed high purity molybdenum single crystals of different orientations were measured. The results were discussed in terms of parameter changes related to quasiparticle or dislocation oscillations, respectively, dislocation point defect interactions as well as defect generation at microplastic deformation.

  4. Na2TiGeO5: Crystal structure stability at low temperature and high pressure

    DEFF Research Database (Denmark)

    Waskowska, A.; Gerward, Leif; Olsen, J.S.

    2008-01-01

    The temperature evolution of the lattice parameters measured from 295 to 125 K exhibits a small instability below T-c approximate to 278 K, indicating ferroelastic properties of Na2TiGeO5. The behavior is related to the specific crystal structure built of polyhedral layers with shared TiO5 pyrami...

  5. Fabrication of colloidal crystal heterostructures by a room temperature floating self-assembly method

    International Nuclear Information System (INIS)

    Wang Aijun; Chen Shengli; Dong Peng

    2011-01-01

    Highlights: → Opal colloidal crystal heterostructure of several square centimeters in area was fabricated within only tens of minutes. → A fabricated colloidal crystal heterostructure was composed of a PS opal and a TiO 2 inverse opal crystal films. → The photonic heterostructure had two photonic-band gaps. → The relative position of the two photonic-band gaps can be controlled by the size of PS microspheres used to fabricate the photonic heterostructure. - Abstract: Photonic crystal heterostructures were fabricated through a room temperature floating self-assembly (RTFSA) method recently developed by our research group. Applying this method, opal colloidal crystal heterostructures of several square centimeters in area were fabricated within tens of minutes without special facilities, and a heterostructure composed of a PS opal and a TiO 2 inverse opal crystal films was fabricated. SEM image of the PS opal-TiO 2 inverse opal heterostructure showed the ordered growth of the top opal film of the heterostructure was hardly disturbed by the cracks in the TiO 2 inverse opal film. The UV-vis transmission spectra indicated that the photonic heterostructures had two photonic-band gaps, and the relative position of two photonic-band gaps can be controlled by the size of PS microspheres used to fabricated the photonic heterostructures.

  6. Temperature-modified photonic bandgap in colloidal photonic crystals fabricated by vinyl functionalized silica spheres

    International Nuclear Information System (INIS)

    Deng Tiansong; Zhang Junyan; Zhu Kongtao; Zhang Qifeng; Wu Jinlei

    2011-01-01

    Graphical abstract: A thermal annealing procedure was described for fine modifying the photonic bandgap properties of colloidal photonic crystals, which were self-assembled from vinyl-functionalized silica spheres by a gravity sedimentation process. Highlights: → We described a thermal annealing procedure for fine modifying the photonic bandgap properties of colloidal photonic crystals. → The position of its stop band had more than 25% blue shift by annealing the sample from 60 to 600 deg. C. → The annealing temperature and the Bragg peak values have a linear relationship in the 120-440 deg. C range. → The effects provide a simple and controllable method for modifying the photonic bandgap properties of colloidal photonic crystals. - Abstract: A thermal annealing procedure for fine modifying the photonic bandgap properties of colloidal photonic crystals was described. The colloidal photonic crystals were assembled from monodisperse vinyl functionalized silica spheres by a gravity sedimentation process. The samples diffract light following Bragg's law combined with Snell's law. By annealing the sample at temperatures in the range of 60-600 deg. C, the position of its stop band shifted from 943 to 706 nm. It had more than 25% blue shift. In addition, the annealing temperature and the Bragg peak values have a linear relationship in the 120-440 deg. C range. Fourier transform infrared (FT-IR) spectra and thermo-gravimetric analysis (TGA) curves of vinyl functionalized silica spheres confirmed the above results. The effects provide a simple and controllable method for modifying the photonic bandgap properties of colloidal photonic crystals.

  7. A Novel Wearable Forehead EOG Measurement System for Human Computer Interfaces.

    Science.gov (United States)

    Heo, Jeong; Yoon, Heenam; Park, Kwang Suk

    2017-06-23

    Amyotrophic lateral sclerosis (ALS) patients whose voluntary muscles are paralyzed commonly communicate with the outside world using eye movement. There have been many efforts to support this method of communication by tracking or detecting eye movement. An electrooculogram (EOG), an electro-physiological signal, is generated by eye movements and can be measured with electrodes placed around the eye. In this study, we proposed a new practical electrode position on the forehead to measure EOG signals, and we developed a wearable forehead EOG measurement system for use in Human Computer/Machine interfaces (HCIs/HMIs). Four electrodes, including the ground electrode, were placed on the forehead. The two channels were arranged vertically and horizontally, sharing a positive electrode. Additionally, a real-time eye movement classification algorithm was developed based on the characteristics of the forehead EOG. Three applications were employed to evaluate the proposed system: a virtual keyboard using a modified Bremen BCI speller and an automatic sequential row-column scanner, and a drivable power wheelchair. The mean typing speeds of the modified Bremen brain-computer interface (BCI) speller and automatic row-column scanner were 10.81 and 7.74 letters per minute, and the mean classification accuracies were 91.25% and 95.12%, respectively. In the power wheelchair demonstration, the user drove the wheelchair through an 8-shape course without collision with obstacles.

  8. Transient post-exercise hyper-perspiration of forehead area | Reza ...

    African Journals Online (AJOL)

    Information about sweating responses during exercise recovery is insufficient and mostly controversial. In the present study, particular attention is given to sweating behavior at forehead area immediately after exercise. Simultaneous changes of some underlying factors are also addressed. Eight healthy young males ...

  9. Finesse in forehead and brow rejuvenation: modern concepts, including endoscopic methods.

    Science.gov (United States)

    Drolet, Brian C; Phillips, Benjamin Z; Hoy, Erik A; Chang, Johnny; Sullivan, Patrick K

    2014-12-01

    The brow and forehead are essential elements of the facial aesthetic architecture. Although frequently overlooked in youth, signs of facial aging are often most noticeable in the upper third of the face. Ptosis and loss of contour in the brows, along with temporal volume loss, sagging of periorbital tissue, and rhytides in the forehead, are common presenting complaints for aesthetic surgery. Although use of nonsurgical procedures (e.g., neuromodulators) has become very common practice, knowledge of surgical anatomy and interventions for brow and forehead rejuvenation are critical for a plastic surgeon. The earliest descriptions of brow-lift procedures are nearly a century old. Techniques have evolved significantly, to the point that patients may now return to work within 1 week of surgery, with minimal or no stigmata from an operation. The literature and a series of cases from the senior surgeon (P.K.S.) were reviewed. A minimally invasive approach with an endoscope for dissection and repositioning of the brow was used in all patients. The authors have found that permanent suture fixation with cortical tunnels can produce an excellent, long-lasting aesthetic result for not only the forehead and brow but also the lateral periorbital and temporal regions. Although each operation is tailored to the patient's individual anatomy, the authors' approach to the endoscopic procedure is described in this article, along with a review of anatomical and surgical considerations. Finally, several patients provide demonstrative results from the senior surgeon's series of 546 patients.

  10. Temperature and concentration quenching of Tb3+ emissions in Y4Al2O9 crystals

    International Nuclear Information System (INIS)

    Boruc, Z.; Fetlinski, B.; Kaczkan, M.; Turczynski, S.; Pawlak, D.; Malinowski, M.

    2012-01-01

    Highlights: ► Spectroscopic properties of Tb 3+ :Y 4 Al 2 O 9 crystals are studied. ► Concentration and temperature dependencies of fluorescence are investigated. ► The cross-relaxation transfer rates are experimentally determined. ► Strong influence of cross relaxation process on 5 D 3 emission quenching is observed. ► Decays are modelled using Inokuti–Hirayama approach. - Abstract: Spectroscopic properties of trivalent terbium (Tb 3+ ) activated Y 4 Al 2 O 9 (abbreviated YAM) crystals were studied. Concentration and temperature dependent emission spectra and fluorescence dynamics profiles have been investigated in YAM:Tb 3+ in order to understand better processes responsible for quenching of the terbium 5 D 3 and 5 D 4 emissions. Decays were modelled using Inokuti–Hirayama approach to obtain information on the energy transfer mechanism. The cross-relaxation transfer rates were experimentally determined as a function of temperature and Tb 3+ concentration. The investigation revealed strong influence of cross-relaxation process on 5 D 3 emission quenching. The two different processes responsible for the increase of fluorescence quenching with growing temperature were observed, both related to thermal activation energy. For temperatures above 700 K, the temperature dependence of the emission intensity ratio ( 5 D 3 / 5 D 4 ) becomes linear and the decay times are rapidly decreasing monotonously with increasing temperature, what is confirming the potential of Y 4 Al 2 O 9 :Tb 3+ material in high temperature luminescence thermometry.

  11. Cu-Al-Ni Shape Memory Single Crystal Wires with High Transformation Temperature

    Science.gov (United States)

    Hautcoeur, Alain; Fouché, Florian; Sicre, Jacques

    2016-01-01

    CN-250X is a new material with higher performance than Nickel-Titanium Shape Memory Alloy (SMA). For space mechanisms, the main disadvantage of Nickel-Titanium Shape Memory Alloy is the limited transformation temperature. The new CN-250X Nimesis alloy is a Cu-Al-Ni single crystal wire available in large quantity because of a new industrial process. The triggering of actuators made with this Cu-Al-Ni single crystal wire can range from ambient temperature to 200 C in cycling and even to 250 C in one-shot mode. Another advantage of CN-250X is a better shape recovery (8 to 10%) than Ni-Ti (6 to 7%). Nimesis is the first company able to produce this type of material with its new special industrial process. A characterization study is presented in this work, including the two main solicitation modes for this material: tensile and torsion. Different tests measure the shape recovery of Cu-Al-Ni single crystals wires during heating from room temperature to a temperature higher than temperature of end of martensitic transformation.

  12. Temperature dependence of radiation colloidal centers production and annealing in alkali halide crystals

    International Nuclear Information System (INIS)

    Kristapson, J.Z.; Ozerskii, V.J.

    1981-01-01

    The investigation results on temperature dependences of production and annealing of radiation colloidal color centers have been reviewed. In order to produce such centers in NaCl, KCl and KBr crystals the doses of 10 2 -10 4 Mrad as well as irradiation temperatures of 300-600 K and post-irradiation heating of up to 800 K were applied. It has been demonstrated that to produce X-centers, it is necessary to have optimal temperature and initial critical dose during both irradiation and post-irradiation heating of crystals. It has been also found that during annealing hole centers produced are different with regard to thermal stability. The possible recombination mechanisms of hole and electron products of radiolysis during post-irradiation heating has been analyzed [ru

  13. Specific features of the temperature dependence of the exciton absorption integral in CdS crystals

    International Nuclear Information System (INIS)

    Novikov, A.B.; Solov'ev, L.E.; Talalaev, V.G.

    1986-01-01

    Cadmium sulfide crystals 0.4-2 μm thick in the 4.2-120 K temperature range are investigated experimentally. The shape of the first exciton absorption line in CdS and dependence of integral exciton absorption factor (IEAF) on the quenching constant j are calculated. Rapid growth of the absorption factor in the maximum of the absorption line and decrease of halfwidth of the factor are shown to take place with j increase. The calculation has disclosed that the Bouguer law is observed excluding negligible IEAF oscillations at variation of crystal thickness. Non-monotonous temperature dependence of IEAF is disclosed in some investigated samples; it, obviously, testifies to non-monotonous temperature dependence of j. Depolarization of the absorption line of high-energy exciton states with n=2 and n=3 is discovered in some samples for the first time

  14. Crystal growth and electronic structure of low-temperature phase SrMgF{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, Victor V. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Functional Electronics Laboratory, Tomsk State University, Tomsk 634050 (Russian Federation); Laboratory of Semiconductor and Dielectric Materials, Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Goloshumova, Alina A. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 630090 (Russian Federation); Isaenko, Ludmila I. [Laboratory of Semiconductor and Dielectric Materials, Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 630090 (Russian Federation); Jiang, Xingxing [BCCRD, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Lobanov, Sergey I. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 630090 (Russian Federation); Zhang, Zhaoming [Australian Nuclear Science & Technology Organisation, Lucas Heights, NSW 2234 (Australia); Lin, Zheshuai, E-mail: zslin@mail.ipc.ac.cn [BCCRD, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2016-04-15

    Using the vertical Bridgman method, the single crystal of low temperature phase SrMgF{sub 4} is obtained. The crystal is in a very good optical quality with the size of 10×7×5 mm{sup 3}. Detailed photoemission spectra of the element core levels are determined by a monochromatic AlKa (1486.6 eV) X-ray source. Moreover, the first-principles calculations are performed to investigate the electronic structure of SrMgF{sub 4}. A good agreement between experimental and calculated results is achieved. It is demonstrated that almost all the electronic orbitals are strongly localized and the hybridization with the others is very small, but the Mg–F bonds covalency is relatively stronger than that of Sr–F bonds. - Graphical abstract: Large size of low-temperature phase SrMgF{sub 4} crystal was obtained (right) and its electronic structure was investigated by X-ray photoelectron spectroscopy and first-principles calculation (left). - Highlights: • Large size single crystal of low-temperature phase SrMgF{sub 4} is obtained. • Electronic structure of SrMgF{sub 4} is measured by X-ray photoelectron spectroscopy. • Partial densities of states are determined by first-principles calculation. • Good agreement between experimental and calculated results is achieved. • Strong ionic characteristics of chemical bonds are exhibited in SrMgF{sub 4}.

  15. Low temperature and high pressure crystals of room temperature ionic liquid: N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate

    International Nuclear Information System (INIS)

    Abe, Hiroshi; Imai, Yusuke; Takekiyo, Takahiro; Yoshimura, Yukihiro; Hamaya, Nozomu

    2014-01-01

    Crystals of room temperature ionic liquid (RTIL) are obtained separately at low temperature or under high pressure. The RTIL is N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate, [DEME][BF 4 ]. At ambient pressure, low-temperature (LT) crystals appeared on slow cooling. By simultaneous X-ray diffraction and differential scanning calorimetry (DSC) measurements, metastable monoclinic and stable orthorhombic phases coexist in pure [DEME][BF 4 ]. Furthermore, the DSC thermal trace indicates that the metastable monoclinic phase was stabilized by adding water. In contrast, on compression process up to 7.6 GPa, crystallization is completely suppressed even upon slow compression. Direct observations using optical microscopy also support no crystal domain growth on compression process. High-pressure (HP) crystals at room temperature were seen only on decompression process, where two different kinds of crystals appeared subsequently. By crystal structure analysis, the LT crystal structures have no relation with the HP ones. Moreover, both metastable monoclinic phase at low temperature and higher pressure crystal has a folding molecular conformation and anti-parallel pairing of the [DEME] cation as the instability factors

  16. Chirp and temperature effects in parametric down conversion from crystals pumped at 800 nm

    Science.gov (United States)

    Sánchez-Lozano, X.; Wiechers, C.; Lucio, J. L.

    2018-04-01

    We consider spontaneous parametric down conversion from aperiodic poled crystals pumped at 800 nm. Our analyses account the effect of internal and external parameters, where, in the former, we include the crystal chirp and length, while in the latter temperature, also the pump chirp and other beam properties. The typical distribution produced is a pop-tab like structure in frequency-momentum space, and our results show that this system is a versatile light source, appropriated to manipulate the frequency and transverse momentum properties of the light produced. We briefly comment on the potential usefulness of the types of telecom wavelength light produced, in particular for quantum information applications.

  17. X-ray characteristic temperature of Fe-Ni alloys with different crystal lattices

    International Nuclear Information System (INIS)

    Krasnikova, G.N.; Ushakov, A.I.; Kazakov, V.G.; Bochkarev, V.F.; Gorovoj, A.M.

    1978-01-01

    Investigated has been the temperature dependence of the thermal expansion coefficient and the characteristic Debye temperature of the ferronickel films, having a body-centered (cubic) and a face-centered (cubic) lattice. In case of the body-centered lattice films the tests have been staged in the 100-200 deg C range, and in case of the face c.entered lattice films - in the 20-300 deg C range. The study of temperature dependence of the thermal expansion coefficient has revealed that a non-linear growth of the thermal expansion coefficient occurs in α-phase samples when approaching the phase transition temperature. The phase transition in the Invar composition Fe-Ni films is conductive to a considerable variation of the Debye temperature. Approaching the phase transition temperature, the crystal lattice dynamic characteristics vary

  18. Shape of isolated domains in lithium tantalate single crystals at elevated temperatures

    International Nuclear Information System (INIS)

    Shur, V. Ya.; Akhmatkhanov, A. R.; Baturin, I. S.; Chezganov, D. S.; Lobov, A. I.; Smirnov, M. M.

    2013-01-01

    The shape of isolated domains has been investigated in congruent lithium tantalate (CLT) single crystals at elevated temperatures and analyzed in terms of kinetic approach. The obtained temperature dependence of the growing domain shape in CLT including circular shape at temperatures above 190 °C has been attributed to increase of relative input of isotropic ionic conductivity. The observed nonstop wall motion and independent domain growth after merging in CLT as opposed to stoichiometric lithium tantalate have been attributed to difference in wall orientation. The computer simulation has confirmed applicability of the kinetic approach to the domain shape explanation

  19. High-Pressure High-Temperature Phase Diagram of the Organic Crystal Paracetamol

    Science.gov (United States)

    Smith, Spencer; Montgomery, Jeffrey; Vohra, Yogesh

    High-pressure high-temperature (HPHT) Raman spectroscopy studies have been performed on the organic crystal paracetamol in a diamond anvil cell utilizing boron-doped diamond as heating anvil. The HPHT data obtained from boron-doped diamond heater is cross-checked with data obtained using a standard block heater diamond anvil cell. Isobaric measurements were conducted at pressures up to 8.5 GPa and temperature up to 520 K in a number of different experiments. Solid state phase transitions from monoclinic Form I --> orthorhombic Form II were observed at various pressures and temperatures as well as transitions from Form II --> unknown Form IV. The melting temperature for paracetamol was observed to increase with increasing pressures to 8.5 GPa. Our previous angle dispersive x-ray diffraction studies at the Advanced Photon Source has confirmed the existence of two unknown crystal structures Form IV and Form V of paracetamol at high pressure and ambient temperature. The phase transformation from Form II to Form IV occurs at ~8.5 GPa and from Form IV to Form V occurs at ~11 GPa at ambient temperature. Our new data is combined with the previous ambient temperature high-pressure Raman and X- ray diffraction data to create the first HPHT phase diagram of paracetamol. Doe-NNSA Carnegie DOE Alliance Center (CDAC) under Grant Number DE-NA0002006.

  20. Room-temperature effects of UV radiation in KBr:Eu{sup 2+} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Salas, R; Melendrez, R [Centro de Investigacion Cientifica y de Educacion Superior de Ensenada - IFUNAM, Ensenada, Apartado Postal 2732 Ensenada, BC, 22800 (Mexico); Aceves, R; Rodriguez, R; Barboza-Flores, M [Centro de Investigacion en Fisica, Universidad de Sonora, Apartado Postal 5-088 Hermosillo, Sonora, 83190 (Mexico)

    1996-07-01

    Thermoluminescence and optical absorption measurements have been carried out in KBr:Eu{sup 2+} crystals irradiated with monochromatic UV light (200-300 nm) and x-rays at room temperature. For UV- and x-irradiated crystals strong similarities between the thermoluminescence glow curves have been found, suggesting that the low-energy UV radiation produces the same defects as produced by x-irradiation in this material. The thermoluminescence glow curves are composed of six glow peaks located at 337, 383, 403, 435, 475 and 509 K. Thermal annealing experiments in previously irradiated crystals show clearly a correlation between the glow peak located at 383 K and the F-centre thermal bleaching process. Also, the excitation spectrum for each thermoluminescence glow peak has been investigated, showing that the low-energy radiation induces the formation of F centres. (author)

  1. Temperature-Induced Lattice Relaxation of Perovskite Crystal Enhances Optoelectronic Properties and Solar Cell Performance

    KAUST Repository

    Banavoth, Murali

    2016-12-14

    Hybrid organic-inorganic perovskite crystals have recently become one of the most important classes of photoactive materials in the solar cell and optoelectronic communities. Albeit improvements have focused on state-of-the-art technology including various fabrication methods, device architectures, and surface passivation, progress is yet to be made in understanding the actual operational temperature on the electronic properties and the device performances. Therefore, the substantial effect of temperature on the optoelectronic properties, charge separation, charge recombination dynamics, and photoconversion efficiency are explored. The results clearly demonstrated a significant enhancement in the carrier mobility, photocurrent, charge carrier lifetime, and solar cell performance in the 60 ± 5 °C temperature range. In this temperature range, perovskite crystal exhibits a highly symmetrical relaxed cubic structure with well-aligned domains that are perpendicular to a principal axis, thereby remarkably improving the device operation. This finding provides a new key variable component and paves the way toward using perovskite crystals in highly efficient photovoltaic cells.

  2. The effect of temperature and pressure on the crystal structure of piperidine.

    Science.gov (United States)

    Budd, Laura E; Ibberson, Richard M; Marshall, William G; Parsons, Simon

    2015-01-01

    The response of molecular crystal structures to changes in externally applied conditions such as temperature and pressure are the result of a complex balance between strong intramolecular bonding, medium strength intermolecular interactions such as hydrogen bonds, and weaker intermolecular van der Waals contacts. At high pressure the additional thermodynamic requirement to fill space efficiently becomes increasingly important. The crystal structure of piperidine-d11 has been determined at 2 K and at room temperature at pressures between 0.22 and 1.09 GPa. Unit cell dimensions have been determined between 2 and 255 K, and at pressures up to 2.77 GPa at room temperature. All measurements were made using neutron powder diffraction. The crystal structure features chains of molecules formed by NH…N H-bonds with van der Waals interactions between the chains. Although the H-bonds are the strongest intermolecular contacts, the majority of the sublimation enthalpy may be ascribed to weaker but more numerous van der Waals interactions. Analysis of the thermal expansion data in the light of phonon frequencies determined in periodic DFT calculations indicates that the expansion at very low temperature is governed by external lattice modes, but above 100 K the influence of intramolecular ring-flexing modes also becomes significant. The principal directions of thermal expansion are determined by the sensitivity of different van der Waals interactions to changes in distance. The principal values of the strain developed on application of pressure are similarly oriented to those determined in the variable-temperature study, but more isotropic because of the need to minimise volume by filling interstitial voids at elevated pressure. Graphical AbstractThough H-bonds are important interactions in the crystal structure of piperidine, the response to externally-applied conditions are determined by van der Waals interactions.

  3. Enzyme catalysis captured using multiple structures from one crystal at varying temperatures

    Directory of Open Access Journals (Sweden)

    Sam Horrell

    2018-05-01

    Full Text Available High-resolution crystal structures of enzymes in relevant redox states have transformed our understanding of enzyme catalysis. Recent developments have demonstrated that X-rays can be used, via the generation of solvated electrons, to drive reactions in crystals at cryogenic temperatures (100 K to generate `structural movies' of enzyme reactions. However, a serious limitation at these temperatures is that protein conformational motion can be significantly supressed. Here, the recently developed MSOX (multiple serial structures from one crystal approach has been applied to nitrite-bound copper nitrite reductase at room temperature and at 190 K, close to the glass transition. During both series of multiple structures, nitrite was initially observed in a `top-hat' geometry, which was rapidly transformed to a `side-on' configuration before conversion to side-on NO, followed by dissociation of NO and substitution by water to reform the resting state. Density functional theory calculations indicate that the top-hat orientation corresponds to the oxidized type 2 copper site, while the side-on orientation is consistent with the reduced state. It is demonstrated that substrate-to-product conversion within the crystal occurs at a lower radiation dose at 190 K, allowing more of the enzyme catalytic cycle to be captured at high resolution than in the previous 100 K experiment. At room temperature the reaction was very rapid, but it remained possible to generate and characterize several structural states. These experiments open up the possibility of obtaining MSOX structural movies at multiple temperatures (MSOX-VT, providing an unparallelled level of structural information during catalysis for redox enzymes.

  4. Characterization and inhibitive study of gel-grown hydroxyapatite crystals at physiological temperature

    Science.gov (United States)

    Parekh, Bharat; Joshi, Mihir; Vaidya, Ashok

    2008-04-01

    Hydroxyapatite is very useful for various biomedical applications, due to its chemical similarity with mineralized bone of human. Hydroxyapatite is also responsible for arthropathy (joint disease). In the present study, the growth of hydroxyapatite crystals was carried out by using single-diffusion gel growth technique in silica hydro gel media, at physiological temperature. The growth of hydroxyapatite crystals under slow and controlled environment in gel medium can be simulated in a simple manner to the growth in human body. The crystals, formed in the Liesegang rings, were characterized by powder XRD, FTIR and dielectric study. The diffusion study is also carried out for the hydroxyapatite crystals using the moving boundary model. The inhibitive influence of various Ayurvedic medicinal plant extracts such as Boswellia serrata gum resin , Tribulus terrestris fruits, Rotula aquatica roots, Boerhaavia diffusa roots and Commiphora wightii, on the growth of hydroxyapatite was studied. Roots of R. aquatica and B. diffusa show some inhibition of the hydroxyapatite crystals in vitro. This preclinical study will be helpful to design the therapy for prevention of hydroxyapatite-based ailments.

  5. Defects of diamond single crystal grown under high temperature and high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Su, Qingcai, E-mail: suqc@sdu.edu.cn [Key Laboratory of Liquid Structure and Heredity of Materials (Ministry of Education), Shandong University, Jinan, P. R. China, 250061 (China); School of Materials Science and Engineering, Shandong University, Jinan, P. R. China, 250061 (China); Shandong Engineering Research Center for Superhard Materials, Zoucheng, P. R. China 273500 (China); Zhang, Jianhua [School of Mechanical Engineering, Shandong University, Jinan, P. R. China, 250061 (China); Li, Musen [Key Laboratory of Liquid Structure and Heredity of Materials (Ministry of Education), Shandong University, Jinan, P. R. China, 250061 (China); School of Materials Science and Engineering, Shandong University, Jinan, P. R. China, 250061 (China); Shandong Engineering Research Center for Superhard Materials, Zoucheng, P. R. China 273500 (China)

    2013-11-01

    The diamond single crystal, synthesized with Fe–Ni–C–B system of catalyst under high temperature and high pressure, had been observed by field emission scanning electron microscope and transmission electron microscope. The presence of a cellular structure suggested that the diamond grew from melted catalyst solution and there existed a zone of component supercooling zone in front of the solid–liquid interface. The main impurities in the diamond crystal was (FeNi){sub 23}C{sub 6}. The triangle screw pit revealed on the (111) plane was generated by the screw dislocation meeting the diamond (111) plane at the points of emergence of dislocations. A narrow twin plane was formed between the two (111) plane. - Highlights: • High pressure, high temperature synthesis of diamond single crystal. • Fe–Ni–C–B used as catalyst, graphite as carbon source. • The main impurity in the diamond crystal was (FeNi){sub 23}C{sub 6}. • Surface defects arose from screw dislocations and stacking faults.

  6. X-ray spectroscopic study of high-temperature plasmas by curved crystal spectrometer

    International Nuclear Information System (INIS)

    Morita, Shigeru.

    1983-07-01

    Extensive studies have been carried out on the structure of X-ray spectra from the highly stripped ions of first transition elements and their behavior in high temperature plasma, using a high resolution crystal spectrometer. Calculation was made on the design and the use of a curved crystal spectrometer for plasma diagnostics. A Johann type crystal spectrometer for measuring X-ray lines was constructed on the basis of the calculation. The characteristics of curved crystals of LiF, Ge and quartz used for the measurement of Kα lines from first transition elements were investigated. Vacuum sparks have been formed for producing high temperature plasma which emits X-ray lines from highly stripped ions. Two different structures of vacuum spark plasma were shown, that is, thermalized point plasma and extended plasma associated with non-thermal electrons. The X-ray lines from the extended plasma, those associated with the K shell from the point plasma and the Kα lines of Ti through Zn from the point plasma have been observed. (Kako, I.)

  7. High-pressure high-temperature phase diagram of organic crystal paracetamol

    Science.gov (United States)

    Smith, Spencer J.; Montgomery, Jeffrey M.; Vohra, Yogesh K.

    2016-01-01

    High-pressure high-temperature (HPHT) Raman spectroscopy studies have been performed on the organic crystal paracetamol in a diamond anvil cell utilizing boron-doped heating diamond anvil. Isobaric measurements were conducted at pressures up to 8.5 GPa and temperature up to 520 K in five different experiments. Solid state phase transitions from monoclinic Form I  →  orthorhombic Form II were observed at various pressures and temperatures as well as transitions from Form II  →  unknown Form IV. The melting temperature for paracetamol was observed to increase with increasing pressures to 8.5 GPa. This new data is combined with previous ambient temperature high-pressure Raman and x-ray diffraction data to create the first HPHT phase diagram of paracetamol.

  8. High-pressure high-temperature phase diagram of organic crystal paracetamol

    International Nuclear Information System (INIS)

    Smith, Spencer J; Montgomery, Jeffrey M; Vohra, Yogesh K

    2016-01-01

    High-pressure high-temperature (HPHT) Raman spectroscopy studies have been performed on the organic crystal paracetamol in a diamond anvil cell utilizing boron-doped heating diamond anvil. Isobaric measurements were conducted at pressures up to 8.5 GPa and temperature up to 520 K in five different experiments. Solid state phase transitions from monoclinic Form I  →  orthorhombic Form II were observed at various pressures and temperatures as well as transitions from Form II  →  unknown Form IV. The melting temperature for paracetamol was observed to increase with increasing pressures to 8.5 GPa. This new data is combined with previous ambient temperature high-pressure Raman and x-ray diffraction data to create the first HPHT phase diagram of paracetamol. (paper)

  9. Effect of smectic A temperature width on the soft mode in ferroelectric liquid crystals

    Science.gov (United States)

    Choudhary, A.; Kaur, S.; Prakash, J.; Sreenivas, K.; Bawa, S. S.; Biradar, A. M.

    2008-08-01

    The behavior of soft mode range with respect to the temperature width of smectic A (Sm A) phase has been studied in four different ferroelectric liquid crystal (FLC) materials in the frequency range 10Hz-10MHz. The studies have been carried out in a planarly well aligned cells at different temperatures and different bias fields in Sm C* and Sm A phases. Dielectric studies of these FLCs near Sm C*-Sm A phase transition show that the temperature range of soft mode relaxation frequency phenomenon varies with the temperature width of Sm A phase. The dependence of tilt angle on temperature shows the nature of the order of transition at Sm C*-Sm A phase. The coupling between order parameters of Sm C* and Sm A phase influences the soft mode and phase transition in Sm C* and Sm A phases.

  10. A Novel High-Sensitivity, Low-Power, Liquid Crystal Temperature Sensor

    Directory of Open Access Journals (Sweden)

    José Francisco Algorri

    2014-04-01

    Full Text Available A novel temperature sensor based on nematic liquid crystal permittivity as a sensing magnitude, is presented. This sensor consists of a specific micrometric structure that gives considerable advantages from other previous related liquid crystal (LC sensors. The analytical study reveals that permittivity change with temperature is introduced in a hyperbolic cosine function, increasing the sensitivity term considerably. The experimental data has been obtained for ranges from −6 °C to 100 °C. Despite this, following the LC datasheet, theoretical ranges from −40 °C to 109 °C could be achieved. These results have revealed maximum sensitivities of 33 mVrms/°C for certain temperature ranges; three times more than of most silicon temperature sensors. As it was predicted by the analytical study, the micrometric size of the proposed structure produces a high output voltage. Moreover the voltage’s sensitivity to temperature response can be controlled by the applied voltage. This response allows temperature measurements to be carried out without any amplification or conditioning circuitry, with very low power consumption.

  11. Co-doped sodium chloride crystals exposed to different irradiation temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz-Morales, A. [Unidad Profesional Interdisciplinaria de Ingenieria y Tecnologias Avanzadas, IPN, Av. Instituto Politecnico Nacional 2580, Col. La Laguna Ticoman, 07340 Mexico D.F., Mexico and Unidad de Irradiacion y Segurid (Mexico); Cruz-Zaragoza, E.; Furetta, C. [Unidad de Irradiacion y Seguridad Radiologica, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, 04510 Mexico D.F (Mexico); Kitis, G. [Nuclear Physics Laboratory, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Flores J, C.; Hernandez A, J.; Murrieta S, H. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP. 20-364, 01000 Mexico D.F (Mexico)

    2013-07-03

    Monocrystals of NaCl:XCl{sub 2}:MnCl{sub 2}(X = Ca,Cd) at four different concentrations have been analyzed. The crystals were exposed to different irradiation temperature, such as at room temperature (RT), solid water (SW), dry ice (DI) and liquid nitrogen (LN). The samples were irradiated with photon from {sup 60}Co irradiators. The co-doped sodium chloride crystals show a complex structure of glow curves that can be related to different distribution of traps. The linearity response was analyzed with the F(D) index. The F(D) value was less than unity indicating a sub-linear response was obtained from the TL response on the function of the dose. The glow curves were deconvoluted by using the CGCD program based on the first, second and general order kinetics.

  12. Advantage of low-temperature hydrothermal synthesis to grow stoichiometric crednerite crystals

    Science.gov (United States)

    Poienar, Maria; Martin, Christine; Lebedev, Oleg I.; Maignan, Antoine

    2018-06-01

    This work reports a new approach for the growth of stoichiometric crednerite CuMnO2 crystals. The hydrothermal reaction, starting from soluble metal sulphates as precursors, is assisted by ethylene glycol and the formation of crednerite is found to depend strongly on pH and temperature. This method allows obtaining small hexagonal platelets with the larger dimension about 1.0-1.5 μm and with a composition characterized by a Cu/Mn ratio of 1. Thus, these crystals differ from the needle-like millimetric ones obtained by the flux technique for which the composition departs from the expected one and is close to Cu1.04Mn0.96. This monitoring of the cationic composition in crednerite, using hydrothermal synthesis, is important as the Cu/Mn ratio controls the low temperature antiferromagnetic ground-state.

  13. Shearing single crystal magnesium in the close-packed basal plane at different temperatures

    Science.gov (United States)

    Han, Ming; Li, Lili; Zhao, Guangming

    2018-05-01

    Shear behaviors of single crystal magnesium (Mg) in close-packed (0001) basal plane along the [ 1 bar 2 1 bar 0 ], [ 1 2 bar 10 ], [ 10 1 bar 0 ] and [ 1 bar 010 ] directions were studied using molecular dynamics simulations via EAM potential. The results show that both shear stress-strain curves along the four directions and the motion path of free atoms during shearing behave periodic characteristics. It reveals that the periodic shear displacement is inherently related to the crystallographic orientation in single crystal Mg. Moreover, different temperatures in a range from 10 to 750 K were considered, demonstrating that shear modulus decreases with increasing temperatures. The results agree well with the MTS model. It is manifested that the modulus is independent with the shear direction and the size of the atomic model. This work also demonstrates that the classical description of shear modulus is still effective at the nanoscale.

  14. Room temperature ferromagnetism in Fe-doped semiconductor ZrS2 single crystals

    Science.gov (United States)

    Muhammad, Zahir; Lv, Haifeng; Wu, Chuanqiang; Habib, Muhammad; Rehman, Zia ur; Khan, Rashid; Chen, Shuangming; Wu, Xiaojun; Song, Li

    2018-04-01

    Two dimensional (2D) layered magnetic materials have obtained much attention due to their intriguing properties with a potential application in the field of spintronics. Herein, room-temperature ferromagnetism with 0.2 emu g‑1 magnetic moment is realized in Fe-doped ZrS2 single crystals of millimeter size, in comparison with diamagnetic behaviour in ZrS2. The electron paramagnetic resonance spectroscopy reveals that 5.2wt% Fe-doping ZrS2 crystal exhibit high spin value of g-factor about 3.57 at room temperature also confirmed this evidence, due to the unpaired electrons created by doped Fe atoms. First principle static electronic and magnetic calculations further confirm the increased stability of long range ferromagnetic ordering and enhanced magnetic moment in Fe-doped ZrS2, originating from the Fe spin polarized electron near the Fermi level.

  15. Pressure effect on crystallization temperature in Zr70Pd30 metallic glass

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Jeppesen, S; Saida, J.

    2004-01-01

    The pressure effect on amorphous-to-quasicrystalline-to-intermetallic phase transformations in a Zr70Pd30 metallic glass has been investigated by in situ x-ray diffraction measurements using synchrotron radiation. It is found that the glass crystallizes in two steps: (1) amorphous...... temperature for the formation of quasicrystals has been further discussed with the nucleation theory. ©2004 American Institute of Physics....

  16. Temperature dependence of CIE-x,y color coordinates in YAG:Ce single crystal phosphor

    Czech Academy of Sciences Publication Activity Database

    Rejman, M.; Babin, Vladimir; Kučerková, Romana; Nikl, Martin

    2017-01-01

    Roč. 187, Jul (2017), s. 20-25 ISSN 0022-2313 R&D Projects: GA TA ČR TA04010135 Institutional support: RVO:68378271 Keywords : YAG:Ce * single-crystal * simulation * energy level lifetime * white LED * CIE * temperature dependence Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.686, year: 2016

  17. Correlation Between Superheated Liquid Fragility And Onset Temperature Of Crystallization For Al-Based Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Guo J.

    2015-06-01

    Full Text Available Amorphous alloys or metallic glasses have attracted significant interest in the materials science and engineering communities due to their unique physical, mechanical, and chemical properties. The viscous flow of amorphous alloys exhibiting high strain rate sensitivity and homogeneous deformation is considered to be an important characteristic in thermoplastic forming processes performed within the supercooled liquid region because it allows superplastic-like deformation behavior. Here, the correlation between the superheated liquid fragility, and the onset temperature of crystallization for Al-based alloys, is investigated. The activation energy for viscous flow of the liquid is also investigated. There is a negative correlation between the parameter of superheated liquid fragility and the onset temperature of crystallization in the same Al-based alloy system. The activation energy decreases as the onset temperature of crystallization increases. This indicates that the stability of a superheated liquid can affect the thermal stability of the amorphous alloy. It also means that a liquid with a large superheated liquid fragility, when rapidly solidified, forms an amorphous alloy with a low thermal stability.

  18. Specific heat studies of pure Nb3Sn single crystals at low temperature

    International Nuclear Information System (INIS)

    Escudero, R; Morales, F; Bernes, S

    2009-01-01

    Specific heat measurements performed on high purity vapor-grown Nb 3 Sn crystals show clear features related to both the martensitic and superconducting transitions. Our measurements indicate that the martensitic anomaly does not display hysteresis, meaning that the martensitic transition could be a weak first-order or a second-order thermodynamic transition. Careful measurements of the two transition temperatures display an inverse correlation between them. At low temperature, specific heat measurements show the existence of a single superconducting energy gap feature.

  19. Temperature effects of Mach-Zehnder interferometer using a liquid crystal-filled fiber

    DEFF Research Database (Denmark)

    Ho, Bo-Yan; Su, Hsien-Pin; Tseng, Yu-Pei

    2015-01-01

    We demonstrated a simple and cost-effective method to fabricate all fiber Mach-Zehnder interferometer (MZI) based on cascading a short section of liquid crystal (LC)-filled hollow-optic fiber (HOF) between two single mode fibers by using automatically splicing technique. The transmission spectra...... of the proposed MZI with different LC-infiltrated length were measured and the temperature-induced wavelength shifts of the interference fringes were recorded. Both blue shift and red shift were observed, depending the temperature range. Based on our experimental results, interference fringe was observed...

  20. Temperature-dependent index of refraction of monoclinic Ga2O3 single crystal.

    Science.gov (United States)

    Bhaumik, Indranil; Bhatt, R; Ganesamoorthy, S; Saxena, A; Karnal, A K; Gupta, P K; Sinha, A K; Deb, S K

    2011-11-01

    We present temperature-dependent refractive index along crystallographic b[010] and a direction perpendicular to (100)-plane for monoclinic phase (β) Ga(2)O(3) single crystal grown by the optical floating zone technique. The experimental results are consistent with the theoretical result of Litimein et al.1. Also, the Sellmeier equation for wavelengths in the range of 0.4-1.55 μm is formulated at different temperatures in the range of 30-175 °C. The thermal coefficient of refractive index in the above specified range is ~10(-5)/°C. © 2011 Optical Society of America

  1. Low temperature ultrasonic investigation of ZnSe crystals doped with Ni

    Energy Technology Data Exchange (ETDEWEB)

    Gudkov, Vladimir [Institute for Metal Physics, Ural Department of the Russian Academy of Sciences, 18, Kovalevskaya st., 620219 Ekaterinburg (Russian Federation); Russian State Vocational Pedagogical University, 11, Mashinostroitelei st., 620012 Ekaterinburg (Russian Federation); Lonchakov, Alexander; Sokolov, Victor; Zhevstovskikh, Irina; Gruzdev, Nikita [Institute for Metal Physics, Ural Department of the Russian Academy of Sciences, 18, Kovalevskaya st., 620219 Ekaterinburg (Russian Federation)

    2005-03-01

    The peak of ultrasonic absorption observed at {approx}13 K in ZnSe:Ni crystals with dopant concentration of 5.5 x 10{sup 19} cm{sup -3} was interpreted as due to the Jahn-Teller effect. The dynamic contribution to the effective elastic modulus was accounted for and the temperature dependences of relaxation time, relaxed and unrelaxed modulus C{sub 44} were obtained. The procedure of accounting for the dynamic contribution resulted in a more accurate determination of the temperature of phase transition. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Laser beam propagation in nematic liquid crystals at the temperature close to the nematicisotropic critical point.

    Science.gov (United States)

    Chen, Yu-Jen; Lin, Yu-Sung; Jiang, I-Min; Tsai, Ming-Shan

    2008-03-17

    This study investigates the optical nonlinearity of beam propagation in homogeneously aligned nematic liquid crystal (NLC) cells at a temperature close to the nematic-isotropic temperature (TNI). The undulate propagation mode with convergent and divergent loops appearing alternately is reported and the thermally enhanced optical reorientation nonlinearity at the focus is described. The optically induced phase transition exists along the pump beam direction. With the application of the conscopic technique, the arrangements of LC at the focus are proposed in this study. Results of this study demonstrate that the evolution of the LC configuration was affected by the pump beam based on the analysis of conoscopic patterns.

  3. LIQUIDUS TEMPERATURE AND ONE PERCENT CRYSTAL CONTENT MODELS FOR INITIAL HANFORD HLW GLASSES

    International Nuclear Information System (INIS)

    Vienna, John D.; Edwards, Tommy B.; Crum, Jarrod V.; Kim, Dong-Sang; Peeler, David K.

    2005-01-01

    Preliminary models for liquidus temperature (TL) and temperature at 1 vol% crystal (T01) applicable to WTP HLW glasses in the spinel primary phase field were developed. A series of literature model forms were evaluated using consistent sets of data form model fitting and validation. For TL, the ion potential and linear mixture models performed best, while for T01 the linear mixture model out performed all other model forms. TL models were able to predict with smaller uncertainty. However, the lower T01 values (even with higher prediction uncertainties) were found to allow for a much broader processing envelope for WTP HLW glasses

  4. crystal

    Science.gov (United States)

    Yu, Yi; Huang, Yisheng; Zhang, Lizhen; Lin, Zhoubin; Sun, Shijia; Wang, Guofu

    2014-07-01

    A Nd3+:Na2La4(WO4)7 crystal with dimensions of ϕ 17 × 30 mm3 was grown by the Czochralski method. The thermal expansion coefficients of Nd3+:Na2La4(WO4)7 crystal are 1.32 × 10-5 K-1 along c-axis and 1.23 × 10-5 K-1 along a-axis, respectively. The spectroscopic characteristics of Nd3+:Na2La4(WO4)7 crystal were investigated. The Judd-Ofelt theory was applied to calculate the spectral parameters. The absorption cross sections at 805 nm are 2.17 × 10-20 cm2 with a full width at half maximum (FWHM) of 15 nm for π-polarization, and 2.29 × 10-20 cm2 with a FWHM of 14 nm for σ-polarization. The emission cross sections are 3.19 × 10-20 cm2 for σ-polarization and 2.67 × 10-20 cm2 for π-polarization at 1,064 nm. The fluorescence quantum efficiency is 67 %. The quasi-cw laser of Nd3+:Na2La4(WO4)7 crystal was performed. The maximum output power is 80 mW. The slope efficiency is 7.12 %. The results suggest Nd3+:Na2La4(WO4)7 crystal as a promising laser crystal fit for laser diode pumping.

  5. New Crystal-Growth Methods for Producing Lattice-Matched Substrates for High-Temperature Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Boatner, L.A.

    2008-06-24

    This effort addressed the technical problem of identifying and growing, on a commercial scale, suitable single-crystal substrates for the subsequent deposition of epitaxial thin films of high temperature semiconductors such as GaN/AlN. The lack of suitable lattice-matched substrate materials was one of the major problem areas in the development of semiconducting devices for use at elevated temperatures as well as practical opto-electronic devices based on Al- and GaN technology. Such lattice-matched substrates are necessary in order to reduce or eliminate high concentrations of defects and dislocations in GaN/AlN and related epitaxial thin films. This effort concentrated, in particular, on the growth of single crystals of ZnO for substrate applications and it built on previous ORNL experience in the chemical vapor transport growth of large single crystals of zinc oxide. This combined expertise in the substrate growth area was further complemented by the ability of G. Eres and his collaborators to deposit thin films of GaN on the subject substrates and the overall ORNL capability for characterizing the quality of such films. The research effort consisted of research on the growth of two candidate substrate materials in conjunction with concurrent research on the growth and characterization of GaN films, i.e. the effort combined bulk crystal growth capabilities in the area of substrate production at both ORNL and the industrial partner, Commercial Crystal Growth Laboratories (CCL), Naples, Florida, with the novel thin-film deposition techniques previously developed in the ORNL SSD.

  6. Scanning tunneling microscope-quartz crystal microbalance study of temperature gradients at an asperity contact.

    Science.gov (United States)

    Pan, L; Krim, J

    2013-01-01

    Investigations of atomic-scale friction frequently involve setups where a tip and substrate are initially at different temperatures. The temperature of the sliding interface upon contact has thus become a topic of interest. A method for detecting initial tip-sample temperature differences at an asperity contact is described, which consists of a scanning tunneling microscope (STM) tip in contact with the surface electrode of a quartz crystal microbalance (QCM). The technique makes use of the fact that a QCM is extremely sensitive to abrupt changes in temperature. In order to demonstrate the technique's capabilities, QCM frequency shifts were recorded for varying initial tip-substrate temperature differences as an STM tip was brought into and out of contact. The results are interpreted within the context of a recent model for thermal heat conduction at an asperity contact, and it is concluded that the transient frequency response is attributable to small changes in temperature close to the region of contact rather than a change in the overall temperature of the QCM itself. For the assumed model parameters, the results moreover reveal substantial temperature discontinuities at the boundary between the tip and the sample, for example, on the order of 10-15 °C for initial temperature differences of 20 °C.

  7. Analogy between temperature dependent radiation effects in alkali halide crystals and crystalline ammonia

    International Nuclear Information System (INIS)

    Blum, A.

    1977-01-01

    Pikaev, Ershov, and Makarov recently reported the characteristic shape of Arrhenius-type dependence for F-centers slow part (millisecond) decay in alkali halide crystals irradiated at different temperatures. The decay rate is constant when the temperature is below the limiting value (T/sub lim/) and exhibits constant activation energy (E/sub A/) at temperatures above T/sub lim/ up to the melting point. A similar dependence has been observed for crystalline ammonia radiolysis yields (H 2 and N 2 ) in the temperature range from 77 to 195 0 K (ammonia melting point) with a limiting value of 105 0 K for N 2 and 119 0 K for H 2 . The coincidence between the alkali halide and ammonia data does not seem to be formal and there are indications showing a closer analogy between these two cases

  8. High temperature defect equilibrium in ZnS:Cu single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lott, K.; Shinkarenko, S.; Tuern, L.; Nirk, T.; Oepik, A. [Department of Materials Science, Tallinn University of Technology, Tallinn (Estonia); Kallavus, U. [Centre for Materials Research, Tallinn University of Technology, Tallinn (Estonia); Gorokhova, E. [Scientific Research and Technological Institute of Optical Material Science, S. I. Vavilov State Optical Institute, All-Russia Science Center, St. Petersburg (Russian Federation); Grebennik, A.; Vishnjakov, A. [Department of Physical Chemistry, D. Mendelejev University of Chemical Technology of Russia, Moscow (Russian Federation)

    2010-07-15

    High temperature investigations in ZnS:Cu crystals were performed under defined conditions. High temperature electrical conductivity and copper solubility data were obtained under different component vapour pressures and under different sample temperatures. The experimental data at sulphur vapour pressure can be explained by the inclusion of abnormal site occupation i.e. by antistructural disorder. Compensating association of copper with this antistructure defect may occur. Antistructure disorder disappears with increasing of zinc vapour pressure and with increasing role of holes in bipolar conductivity. The method for solving the system of quasichemical reactions without approximation was used to model high temperature defect equilibrium. This model contains antistructure disorder and copper solubility limitation. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  9. An X-ray camera for single-crystal studies at high temperatures under controlled atmosphere

    International Nuclear Information System (INIS)

    Adlhart, W.; Tzafaras, N.; Sueno, S.; Jagodzinski, H.; Huber, H.

    1982-01-01

    A vacuum heating camera has been developed for extremely low background X-ray film work between room temperature and 2000 K. It can be used with modified conventional Weissenberg goniometers and with a specially designed focusing goniometer. The temperature control is maintained by a Pt/Pt-10% Rh thermocouple, a three-term proportional, integral and derivative (PID) controller and a programmable power supply. The accuracy in the absolute temperature setting is 10 K, the stability better than 1 K and the maximum thermal gradient over the crystal 7 K mm -1 at 1330 K. A small oxygen pressure can be applied, depending on the temperature, to control oxidation or reduction reactions of the sample. (Auth.)

  10. Glass transition in thaumatin crystals revealed through temperature-dependent radiation-sensitivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Warkentin, Matthew, E-mail: maw64@cornell.edu; Thorne, Robert E. [Physics Department, Cornell University, Ithaca, New York (United States)

    2010-10-01

    Radiation damage to protein crystals exhibits two regimes of temperature-activated behavior between T = 300 and 100 K, with a crossover at the protein glass transition near 200 K. These results have implications for mechanistic studies of proteins and for structure determination when cooling to T = 100 K creates excessive disorder. The temperature-dependence of radiation damage to thaumatin crystals between T = 300 and 100 K is reported. The amount of damage for a given dose decreases sharply as the temperature decreases from 300 to 220 K and then decreases more gradually on further cooling below the protein-solvent glass transition. Two regimes of temperature-activated behavior were observed. At temperatures above ∼200 K the activation energy of 18.0 kJ mol{sup −1} indicates that radiation damage is dominated by diffusive motions in the protein and solvent. At temperatures below ∼200 K the activation energy is only 1.00 kJ mol{sup −1}, which is of the order of the thermal energy. Similar activation energies describe the temperature-dependence of radiation damage to a variety of solvent-free small-molecule organic crystals over the temperature range T = 300–80 K. It is suggested that radiation damage in this regime is vibrationally assisted and that the freezing-out of amino-acid scale vibrations contributes to the very weak temperature-dependence of radiation damage below ∼80 K. Analysis using the radiation-damage model of Blake and Phillips [Blake & Phillips (1962 ▶), Biological Effects of Ionizing Radiation at the Molecular Level, pp. 183–191] indicates that large-scale conformational and molecular motions are frozen out below T = 200 K but become increasingly prevalent and make an increasing contribution to damage at higher temperatures. Possible alternative mechanisms for radiation damage involving the formation of hydrogen-gas bubbles are discussed and discounted. These results have implications for mechanistic studies of proteins and for

  11. A low temperature drift coefficient crystal-less frequency reference clock compensated by temperature sensor for microsystem

    Science.gov (United States)

    Gao, Zhiqiang; Wu, Ruixuan; Wang, Yuteng; Gao, Yuan; Liu, Xiaowei; Zhu, Jiaqi

    2018-05-01

    Quartz oscillator has been widely used as reference clock source in the microsystems due to its good performance. But a good crystal oscillator costs too much and its bulky size is not desired. This paper aims at designing an alternative integrated oscillator to replace the external quartz oscillator. The proposed circuit used maneatis delay cell to construct a ring oscillator for its superior linear I-V characteristic. As for a frequency reference clock, its frequency stability over temperature is required at first. After detailed mathematical deducing and careful analysis, a formula is proposed to describe the relationship between desired control voltage and temperature by assuming the frequency as constant. This paper utilized bipolar transistor as the temperature sensor, combining it with CTAT current source and resistor to create a first-order temperature compensation control voltage. The chip with typical frequency of 10 MHz was fabricated in a 0.35 μm CMOS technology and occupied 0.45 mm2. The measured results show that the frequency variation is ±0.2% for supply changes from 4.8 V to 5 V, and frequency variation is 48 ppm when the temperature change is from ‑40∘C to 85∘C, while the average current of the tested chip consumes 50 μA from 5 V.

  12. Temperature dependence of the defect luminescence in La2Be2O5 single crystals

    International Nuclear Information System (INIS)

    Ogorodnikov, I.N.; Pustovarov, V.A.

    2015-01-01

    Temperature quenching (TQ) curves in the temperature range of 80–500 K have been studied for both the undoped, and doped with RE 3+ -ions (RE = Ce, Eu, Er, Pr, Nd) lanthanum beryllate (BLO) single crystals. Photoluminescence spectra and TQ-curves were recorded upon excitation in the absorption bands of the lattice defects. The reaction rate model has been developed to describe the experimental results. The model includes two competing processes with characteristic temperatures: thermal quenching of intracenter PL (T 1 ) and thermally stimulated migration of electronic excitations (T 2 ). The competition between these two processes leads to the observed non-monotonic TQ-curves. The rationalized formulas using three parameters (intensity, activation energy, characteristic temperature), were developed to describe each of these processes. Within the framework of the unified model, all the experimental results were described and the best fit parameters were obtained. Classification of the investigated lanthanum beryllate crystals was carried out in line with the best fit parameters obtained for the TQ-curves. - Highlights: • We studied La 2 Be 2 O 5 (BLO) single crystals (pristine and RE 3+ -doped). • We studied PL emission spectra of defects in BLO and BLO:RE 3+ . • Temperature quenching of the defect PL emission was studied at 80–500 K. • We developed the reaction rate model to describe non-monotonic TQ-curves. • TQ-curves were parameterized for BLO, BLO:RE 3+ (RE = Ce, Pr, Eu, Nd, Er).

  13. A Novel Wearable Forehead EOG Measurement System for Human Computer Interfaces

    OpenAIRE

    Heo, Jeong; Yoon, Heenam; Park, Kwang Suk

    2017-01-01

    Amyotrophic lateral sclerosis (ALS) patients whose voluntary muscles are paralyzed commonly communicate with the outside world using eye movement. There have been many efforts to support this method of communication by tracking or detecting eye movement. An electrooculogram (EOG), an electro-physiological signal, is generated by eye movements and can be measured with electrodes placed around the eye. In this study, we proposed a new practical electrode position on the forehead to measure EOG ...

  14. Study of the effect of doping on the temperature stability of the optical properties of germanium single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Podkopaev, O. I. [Joint-Stock Company “Germanium” (Russian Federation); Shimanskiy, A. F., E-mail: shimanaf@mail.ru [Siberian Federal University (Russian Federation); Kopytkova, S. A.; Filatov, R. A. [Joint-Stock Company “Germanium” (Russian Federation); Golubovskaya, N. O. [Siberian Federal University (Russian Federation)

    2016-10-15

    The effect of doping on the optical transmittance of germanium single crystals is studied by infrared Fourier spectroscopy. It is established that the introduction of silicon and tellurium additives into germanium doped with antimony provides a means for improving the temperature stability of the optical properties of the crystals.

  15. Method of determination of temperature and heat resistance of the points on the integrated circuit crystal surface

    Directory of Open Access Journals (Sweden)

    Popov V. M.

    2011-12-01

    Full Text Available Method for visualization of integrated circuit (IC surface temperature by means of the liquid crystal film deposited from solution on its surface is proposed. The boundaries of local regions represent isotherms with corresponding phase transitions. On the base of isotherms positions and consumed by IC power thermal resistances between crystal and environment are determined.

  16. Study of the effect of doping on the temperature stability of the optical properties of germanium single crystals

    International Nuclear Information System (INIS)

    Podkopaev, O. I.; Shimanskiy, A. F.; Kopytkova, S. A.; Filatov, R. A.; Golubovskaya, N. O.

    2016-01-01

    The effect of doping on the optical transmittance of germanium single crystals is studied by infrared Fourier spectroscopy. It is established that the introduction of silicon and tellurium additives into germanium doped with antimony provides a means for improving the temperature stability of the optical properties of the crystals.

  17. Constitutive modeling of creep behavior in single crystal superalloys: Effects of rafting at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Ya-Nan, E-mail: fanyn12@mails.tsinghua.edu.cn; Shi, Hui-Ji, E-mail: shihj@mail.tsinghua.edu.cn; Qiu, Wen-Hui

    2015-09-17

    Rafting and creep modeling of single crystal superalloys at high temperatures are important for the safety assessment and life prediction in practice. In this research, a new model has been developed to describe the rafting evolution and incorporated into the Cailletaud single crystal plasticity model to simulate the creep behavior. The driving force of rafting is assumed to be the relaxation of the strain energy, and it is calculated with the local stress state, a superposition of the external and misfit stress tensors. In addition, the isotropic coarsening is introduced by the cube root dependence of the microstructure periodicity on creep time based on Ostwal ripening. Then the influence of rafting on creep deformation is taken into account as the Orowan stress in the single crystal plasticity model. The capability of the proposed model is validated with creep experiments of CMSX-4 at 950 °C and 1050 °C. It is able to predict the rafting direction at complex loading conditions and evaluate the channel width during rafting. For [001] tensile creep tests, good agreement has been shown between the model predictions and experimental results at different temperatures and stress levels. The creep acceleration can be captured with this model and is attributed to the microstructure degradation caused by the precipitate coarsening.

  18. Control of polythiophene film microstructure and charge carrier dynamics through crystallization temperature

    KAUST Repository

    Marsh, Hilary S.; Reid, Obadiah G.; Barnes, George; Heeney, Martin; Stingelin, Natalie; Rumbles, Garry

    2014-01-01

    The microstructure of neat conjugated polymers is crucial in determining the ultimate morphology and photovoltaic performance of polymer/fullerene blends, yet until recently, little work has focused on controlling the former. Here, we demonstrate that both the long-range order along the (100)-direction and the lamellar crystal thickness along the (001)-direction in neat poly(3-hexylthiophene) (P3HT) and poly[(3,3″-didecyl[2,2′:5′, 2″-terthiophene]-5,5″-diyl)] (PTTT-10) thin films can be manipulated by varying crystallization temperature. Changes in crystalline domain size impact the yield and dynamics of photogenerated charge carriers. Time-resolved microwave conductivity measurements show that neat polymer films composed of larger crystalline domains have longer photoconductance lifetimes and charge carrier yield decreases with increasing crystallite size for P3HT. Our results suggest that the classical polymer science description of temperature-dependent crystallization of polymers from solution can be used to understand thin-film formation in neat conjugated polymers, and hence, should be considered when discussing the structural evolution of organic bulk heterojunctions. © 2014 Wiley Periodicals, Inc.

  19. Control of polythiophene film microstructure and charge carrier dynamics through crystallization temperature

    KAUST Repository

    Marsh, Hilary S.

    2014-03-22

    The microstructure of neat conjugated polymers is crucial in determining the ultimate morphology and photovoltaic performance of polymer/fullerene blends, yet until recently, little work has focused on controlling the former. Here, we demonstrate that both the long-range order along the (100)-direction and the lamellar crystal thickness along the (001)-direction in neat poly(3-hexylthiophene) (P3HT) and poly[(3,3″-didecyl[2,2′:5′, 2″-terthiophene]-5,5″-diyl)] (PTTT-10) thin films can be manipulated by varying crystallization temperature. Changes in crystalline domain size impact the yield and dynamics of photogenerated charge carriers. Time-resolved microwave conductivity measurements show that neat polymer films composed of larger crystalline domains have longer photoconductance lifetimes and charge carrier yield decreases with increasing crystallite size for P3HT. Our results suggest that the classical polymer science description of temperature-dependent crystallization of polymers from solution can be used to understand thin-film formation in neat conjugated polymers, and hence, should be considered when discussing the structural evolution of organic bulk heterojunctions. © 2014 Wiley Periodicals, Inc.

  20. Temperature sensitivity of void nucleation and growth parameters for single crystal copper: a molecular dynamics study

    International Nuclear Information System (INIS)

    Rawat, S; Chavan, V M; Warrier, M; Chaturvedi, S

    2011-01-01

    The effect of temperature on the void nucleation and growth is studied using the molecular dynamics (MD) code LAMMPS (Large-Scale Atomic/Molecular Massively Parallel Simulator). Single crystal copper is triaxially expanded at 5 × 10 9  s −1 strain rate keeping the temperature constant. It is shown that the nucleation and growth of voids at these atomistic scales follows a macroscopic nucleation and growth (NAG) model. As the temperature increases there is a steady decrease in the nucleation and growth thresholds. As the melting point of copper is approached, a double-dip in the pressure–time profile is observed. Analysis of this double-dip shows that the first minimum corresponds to the disappearance of the long-range order due to the creation of stacking faults and the system no longer has a FCC structure. There is no nucleation of voids at this juncture. The second minimum corresponds to the nucleation and incipient growth of voids. We present the sensitivity of NAG parameters to temperature and the analysis of double-dip in the pressure–time profile for single crystal copper at 1250 K

  1. Structure determination of an integral membrane protein at room temperature from crystals in situ

    International Nuclear Information System (INIS)

    Axford, Danny; Foadi, James; Hu, Nien-Jen; Choudhury, Hassanul Ghani; Iwata, So; Beis, Konstantinos; Evans, Gwyndaf; Alguel, Yilmaz

    2015-01-01

    The X-ray structure determination of an integral membrane protein using synchrotron diffraction data measured in situ at room temperature is demonstrated. The structure determination of an integral membrane protein using synchrotron X-ray diffraction data collected at room temperature directly in vapour-diffusion crystallization plates (in situ) is demonstrated. Exposing the crystals in situ eliminates manual sample handling and, since it is performed at room temperature, removes the complication of cryoprotection and potential structural anomalies induced by sample cryocooling. Essential to the method is the ability to limit radiation damage by recording a small amount of data per sample from many samples and subsequently assembling the resulting data sets using specialized software. The validity of this procedure is established by the structure determination of Haemophilus influenza TehA at 2.3 Å resolution. The method presented offers an effective protocol for the fast and efficient determination of membrane-protein structures at room temperature using third-generation synchrotron beamlines

  2. Single-Crystal Tungsten Carbide in High-Temperature In-Situ Additive Manufacturing Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Kolopus, James A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Boatner, Lynn A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-05-18

    Nanoindenters are commonly used for measuring the mechanical properties of a wide variety of materials with both industrial and scientific applications. Typically, these instruments employ an indenter made of a material of suitable hardness bonded to an appropriate shaft or holder to create an indentation on the material being tested. While a variety of materials may be employed for the indenter, diamond and boron carbide are by far the most common materials used due to their hardness and other desirable properties. However, as the increasing complexity of new materials demands a broader range of testing capabilities, conventional indenter materials exhibit significant performance limitations. Among these are the inability of diamond indenters to perform in-situ measurements at temperatures above 600oC in air due to oxidation of the diamond material and subsequent degradation of the indenters mechanical properties. Similarly, boron carbide also fails at high temperature due to fracture. [1] Transition metal carbides possess a combination of hardness and mechanical properties at high temperatures that offer an attractive alternative to conventional indenter materials. Here we describe the technical aspects for the growth of single-crystal tungsten carbide (WC) for use as a high-temperature indenter material, and we examine a possible approach to brazing these crystals to a suitable mount for grinding and attachment to the indenter instrument. The use of a by-product of the recovery process is also suggested as possibly having commercial value.

  3. Temperature dependent evolution of wrinkled single-crystal silicon ribbons on shape memory polymers.

    Science.gov (United States)

    Wang, Yu; Yu, Kai; Qi, H Jerry; Xiao, Jianliang

    2017-10-25

    Shape memory polymers (SMPs) can remember two or more distinct shapes, and thus can have a lot of potential applications. This paper presents combined experimental and theoretical studies on the wrinkling of single-crystal Si ribbons on SMPs and the temperature dependent evolution. Using the shape memory effect of heat responsive SMPs, this study provides a method to build wavy forms of single-crystal silicon thin films on top of SMP substrates. Silicon ribbons obtained from a Si-on-insulator (SOI) wafer are released and transferred onto the surface of programmed SMPs. Then such bilayer systems are recovered at different temperatures, yielding well-defined, wavy profiles of Si ribbons. The wavy profiles are shown to evolve with time, and the evolution behavior strongly depends on the recovery temperature. At relatively low recovery temperatures, both wrinkle wavelength and amplitude increase with time as evolution progresses. Finite element analysis (FEA) accounting for the thermomechanical behavior of SMPs is conducted to study the wrinkling of Si ribbons on SMPs, which shows good agreement with experiment. Merging of wrinkles is observed in FEA, which could explain the increase of wrinkle wavelength observed in the experiment. This study can have important implications for smart stretchable electronics, wrinkling mechanics, stimuli-responsive surface engineering, and advanced manufacturing.

  4. Structure determination of an integral membrane protein at room temperature from crystals in situ

    Energy Technology Data Exchange (ETDEWEB)

    Axford, Danny [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Foadi, James [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Hu, Nien-Jen; Choudhury, Hassanul Ghani [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom); Iwata, So [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom); Kyoto University, Kyoto 606-8501 (Japan); Beis, Konstantinos [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom); Evans, Gwyndaf, E-mail: gwyndaf.evans@diamond.ac.uk [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Alguel, Yilmaz, E-mail: gwyndaf.evans@diamond.ac.uk [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom)

    2015-05-14

    The X-ray structure determination of an integral membrane protein using synchrotron diffraction data measured in situ at room temperature is demonstrated. The structure determination of an integral membrane protein using synchrotron X-ray diffraction data collected at room temperature directly in vapour-diffusion crystallization plates (in situ) is demonstrated. Exposing the crystals in situ eliminates manual sample handling and, since it is performed at room temperature, removes the complication of cryoprotection and potential structural anomalies induced by sample cryocooling. Essential to the method is the ability to limit radiation damage by recording a small amount of data per sample from many samples and subsequently assembling the resulting data sets using specialized software. The validity of this procedure is established by the structure determination of Haemophilus influenza TehA at 2.3 Å resolution. The method presented offers an effective protocol for the fast and efficient determination of membrane-protein structures at room temperature using third-generation synchrotron beamlines.

  5. Temperature induced Spin Switching in SmFeO3 Single Crystal

    Science.gov (United States)

    Cao, Shixun; Zhao, Huazhi; Kang, Baojuan; Zhang, Jincang; Ren, Wei

    2014-08-01

    The prospect of controlling the magnetization (M) of a material is of great importance from the viewpoints of fundamental physics and future applications of emerging spintronics. A class of rare-earth orthoferrites RFeO3 (R is rare-earth element) materials exhibit striking physical properties of spin switching and magnetization reversal induced by temperature and/or applied magnetic field. Furthermore, due to the novel magnetic, magneto-optic and multiferroic properties etc., RFeO3 materials are attracting more and more interests in recent years. We have prepared and investigated a prototype of RFeO3 materials, namely SmFeO3 single-crystal. And we report magnetic measurements upon both field cooling (FC) and zero-field cooling (ZFC) of the sample, as a function of temperature and applied magnetic field. The central findings of this study include that the magnetization of single-crystal SmFeO3 can be switched by temperature, and tuning the magnitude of applied magnetic field allows us to realize such spin switching even at room temperature.

  6. Anomalous temperature dependence of layer spacing of de Vries liquid crystals: Compensation model

    Energy Technology Data Exchange (ETDEWEB)

    Merkel, K. [Central Mining Institute, Katowice 40-166 (Poland); Kocot, A. [Institute of Physics, Silesian University, Katowice 40-007 (Poland); Vij, J. K., E-mail: jvij@tcd.ie [Department of Electronic and Electrical Engineering, Trinity College, The University of Dublin, Dublin 2 (Ireland); Stevenson, P. J.; Panov, A.; Rodriguez, D. [School of Chemistry and Chemical Engineering, Queens University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom)

    2016-06-13

    Smectic liquid crystals that exhibit temperature independent layer thickness offer technological advantages for their use in displays and photonic devices. The dependence of the layer spacing in SmA and SmC phases of de Vries liquid crystals is found to exhibit distinct features. On entering the SmC phase, the layer thickness initially decreases below SmA to SmC (T{sub A–C}) transition temperature but increases anomalously with reducing temperature despite the molecular tilt increasing. This anomalous observation is being explained quantitatively. Results of IR spectroscopy show that layer shrinkage is caused by tilt of the mesogen's rigid core, whereas the expansion is caused by the chains getting more ordered with reducing temperature. This mutual compensation arising from molecular fragments contributing to the layer thickness differs from the previous models. The orientational order parameter of the rigid core of the mesogen provides direct evidence for de Vries cone model in the SmA phase for the two compounds investigated.

  7. Posterior Ciliary Artery Occlusion Caused by Hyaluronic Acid Injections Into the Forehead: A Case Report.

    Science.gov (United States)

    Hu, Xiu Zhuo; Hu, Jun Yan; Wu, Peng Sen; Yu, Sheng Bo; Kikkawa, Don O; Lu, Wei

    2016-03-01

    Although cosmetic facial soft tissue fillers are generally safe and effective, improper injections can lead to devastating and irreversible consequences. We represent the first known case of posterior ciliary artery occlusion caused by hyaluronic acid. A 41-year-old female presented with right visual loss 7 hours after receiving cosmetic hyaluronic acid injections into her forehead. Examination revealed no light perception in the right eye and multiple dark ischemic area of injection over the forehead and nose. The right fundus revealed a pink retina with optic nerve edema. Fluorescein angiogram showed several filling defects in the choroidal circulation and late hyperfluorescence in the choroid. A right posterior ciliary artery occlusion and embolic occlusion of facial artery braches was diagnosed. With hyaluronidase injection, hyperbaric oxygen therapy, oral aspirin, oral acetazolamide and dexamethasone venotransfuse treatment, the patient's forehead and nasal skin improved and vision recovered to hand movements. With proper technique, vascular occlusion is rare following facial filler injection. Vision consequences can be severe if filler emboli enter the ocular circulation. Physicians should be aware of this potential side effect, recognize its presentation, and be knowledgeable of effective management.

  8. Forehead reflectance photoplethysmography to monitor heart rate: preliminary results from neonatal patients

    International Nuclear Information System (INIS)

    Grubb, M R; Carpenter, J; Crowe, J A; Teoh, J; Hayes-Gill, B R; Marlow, N; Ward, C; Mann, C; Sharkey, D

    2014-01-01

    Around 5%–10% of newborn babies require some form of resuscitation at birth and heart rate (HR) is the best guide of efficacy. We report the development and first trial of a device that continuously monitors neonatal HR, with a view to deployment in the delivery room to guide newborn resuscitation. The device uses forehead reflectance photoplethysmography (PPG) with modulated light and lock-in detection. Forehead fixation has numerous advantages including ease of sensor placement, whilst perfusion at the forehead is better maintained in comparison to the extremities. Green light (525 nm) was used, in preference to the more usual red or infrared wavelengths, to optimize the amplitude of the pulsatile signal. Experimental results are presented showing simultaneous PPG and electrocardiogram (ECG) HRs from babies (n = 77), gestational age 26–42 weeks, on a neonatal intensive care unit. In babies ⩾32 weeks gestation, the median reliability was 97.7% at ±10 bpm and the limits of agreement (LOA) between PPG and ECG were +8.39 bpm and −8.39 bpm. In babies <32 weeks gestation, the median reliability was 94.8% at ±10 bpm and the LOA were +11.53 bpm and −12.01 bpm. Clinical evaluation during newborn deliveries is now underway. (paper)

  9. Directional Acoustic Wave Manipulation by a Porpoise via Multiphase Forehead Structure

    Science.gov (United States)

    Zhang, Yu; Song, Zhongchang; Wang, Xianyan; Cao, Wenwu; Au, Whitlow W. L.

    2017-12-01

    Porpoises are small-toothed whales, and they can produce directional acoustic waves to detect and track prey with high resolution and a wide field of view. Their sound-source sizes are rather small in comparison with the wavelength so that beam control should be difficult according to textbook sonar theories. Here, we demonstrate that the multiphase material structure in a porpoise's forehead is the key to manipulating the directional acoustic field. Computed tomography (CT) derives the multiphase (bone-air-tissue) complex, tissue experiments obtain the density and sound-velocity multiphase gradient distributions, and acoustic fields and beam formation are numerically simulated. The results suggest the control of wave propagations and sound-beam formations is realized by cooperation of the whole forehead's tissues and structures. The melon size significantly impacts the side lobes of the beam and slightly influences the main beams, while the orientation of the vestibular sac mainly adjusts the main beams. By compressing the forehead complex, the sound beam can be expanded for near view. The porpoise's biosonar allows effective wave manipulations for its omnidirectional sound source, which can help the future development of miniaturized biomimetic projectors in underwater sonar, medical ultrasonography, and other ultrasonic imaging applications.

  10. Referred pain to the ipsilateral forehead and orbit: An unusual phenomenon during bronchial artery embolization

    International Nuclear Information System (INIS)

    Ramakantan, Ravi; Ketkar, Manoj; Maddali, Krishna; Deshmukh, Hemant

    1999-01-01

    Purpose: We report an unusual pattern of referred pain to the ipsilateral forehead and orbit observed during bronchial artery embolization (BAE) for massive hemoptysis due to pulmonary tuberculosis (TB) and postulate possible neural mechanisms for its occurrence.Methods: Seven men, from a series of 194 patients (171 men, 23 women) undergoing BAE (right bronchial artery 4, left 3) with gelatin sponge for control of massive hemoptysis due to pulmonary TB form the subject of this report.Results: Embolization was successful in achieving control of hemoptysis in these patients and there were no complications following the embolization. Transient, moderately severe, ipsilateral supraorbital and/or retroorbital pain occurred only during the injection of the gelatin sponge contrast mixture into the bronchial artery. The pain did not occur during the injection of heparinized saline or ionic contrast medium.Conclusions: Referred pain during BAE is an unusual phenomenon. Acute vessel distension triggering visceral sensations is probably the causative mechanism. Sympathetic afferents from the bronchi coursing through the posterior pulmonary plexus eventually pass to the trigeminal ganglion via the carotid sympathetic chain. The ophthalmic and maxillary divisions of the trigeminal nerve then mediate pain sensation to the ipsilateral forehead and orbit. Similarly, parasympathetic afferents from the pulmonary plexus crossing the nucleus of the spinal tract of the trigeminal nerve may be responsible for interexchange of impulses to the neurons in this nucleus. Sensory fibers of the ophthalmic and maxillary nerves relaying in this nucleus are then involved in this pain being referred to the forehead and orbit.

  11. Temperature driven structural-memory-effects in carbon nanotubes filled with Fe3C nano crystals

    Science.gov (United States)

    Boi, Filippo S.; Zhang, Xiaotian; Corrias, Anna

    2018-02-01

    We report the observation of novel temperature-driven structural-memory-effects in carbon nanotubes (CNTs) filled with Fe3C nano-crystals. These structural-transitions were measured by means of temperature (T) dependent x-ray diffraction (XRD) in the T-range from 298 K to 12 K. A clear reversible 2θ-shift in the 002-peak of the graphitic-CNTs-walls is found with the decrease of the temperature. As determined by Rietveld refinement, such 2θ-shift translates in a not previously reported decrease in the value of the CNT graphitic c-axis with the decrease of the temperature (from 298 K to 12 K). Also, a clear reversible 2θ-shift in the 031 and 131 diffraction-peaks of Fe3C is observed within the same T-range. Rietveld refinements confirm the existence of such memory-effect and also reveal a gradual decrease of the 010-axis of Fe3C with the decrease of the temperature. These observations imply that the observed structural-memory-effect is a characteristic of CNTs when Fe3C is the encapsulated ferromagnet. The generality of such memory-effects was further confirmed by additional measurements performed on other types of CNTs characterized by continuous Fe3C-filling. XRD measurements in the T-range from 298 K to 673 K revealed also an unusual reversible decrease of the Fe3C-peak intensities with the increase of the temperature. These observations can have important implications on the magnetic data recording applications of these nanostructures by helping in better understanding the unusual temperature-dependent magnetic instabilities of iron-based nano-crystals which have been recently reported in literature.

  12. Laser parameters of a Fe : ZnSe crystal in the 85-255-K temperature range

    NARCIS (Netherlands)

    Voronov, AA; Kozlovskii, [No Value; Korostelin, YV; Podmar'kov, YP; Frolov, MP

    The temperature dependence of the efficiency of a laser based on a Fe:ZnSe crystal grown from the vapour phase by the free-growth method is studied in the 85-255-K temperature range. As the temperature was increased, the slope efficiency of the laser with respect to absorbed energy decreased from

  13. Study on the temperature gradient evolution of large size nonlinear crystal based on the fluid-solid coupling theory

    Science.gov (United States)

    Sun, F. Z.; Zhang, P.; Liang, Y. C.; Lu, L. H.

    2014-09-01

    In the non-critical phase-matching (NCPM) along the Θ =90° direction, ADP and DKDP crystals which have many advantages, including a large effective nonlinear optical coefficient, a small PM angular sensitivity and non beam walk-off, at the non-critical phase-matching become the competitive candidates in the inertial confinement fusion(ICF) facility, so the reasonable temperature control of crystals has become more and more important .In this paper, the fluid-solid coupling models of ADP crystal and DKDP crystal which both have anisotropic thermal conductivity in the states of vacuum and non-vacuum were established firstly, and then simulated using the fluid analysis software Fluent. The results through the analysis show that the crystal surface temperature distribution is a ring shape, the temperature gradients in the direction of the optical axis both the crystals are 0.02°C and 0.01°C due to the air, the lowest temperature points of the crystals are both at the center of surface, and the temperatures are lower than 0.09°C and 0.05°C compared in the vacuum and non-vacuum environment, then propose two designs for heating apparatus.

  14. Room-temperature light-emission from Ge quantum dots in photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Xia Jinsong [Advanced Research Laboratories, Musashi Institute of Technolgy, 8-15-1 Todoroki, Setagaya-ku, Tokyo 158-0082 (Japan)], E-mail: jxia@sc.musashi-tech.ac.jp; Nemoto, Koudai; Ikegami, Yuta [Advanced Research Laboratories, Musashi Institute of Technolgy, 8-15-1 Todoroki, Setagaya-ku, Tokyo 158-0082 (Japan); Usami, Noritaka [Institute of Materials Research, Tohoku University, 2-2-1 Katahira, Aoba-ku, Sendai Japan (Japan)], E-mail: usa@imr.tohoku.ac.jp; Nakata, Yasushi [Horiba, Ltd., 1-7-8 Higashi-Kanda, Chiyoda-ku, Tokyo 101-0031 (Japan)], E-mail: yasushi.nakata@horiba.com; Shiraki, Yasuhiro [Advanced Research Laboratories, Musashi Institute of Technolgy, 8-15-1 Todoroki, Setagaya-ku, Tokyo 158-0082 (Japan)

    2008-11-03

    Multiple layers of Ge self-assembled quantum dots were embedded into two-dimensional silicon photonic crystal microcavities fabricated on silicon-on-insulator substrates. Microphotoluminescence was used to study the light-emission characteristic of the Ge quantum dots in the microcavities. Strong resonant room-temperature light-emission was observed in the telecommunication wavelength region. Significant enhancement of the luminescence from Ge dots was obtained due to the resonance in the cavities. Multiple sharp resonant peaks dominated the spectrum, showing strong optical resonance inside the cavity. By changing the lattice constant of photonic crystal structure, the wavelengths of the resonant peaks are tuned in the wide wavelength range from 1.2 to 1.6 {mu}m.

  15. Low Temperature Synthesis of Metal Oxides by a Supercritical Seed Enhanced Crystallization (SSEC) Process

    DEFF Research Database (Denmark)

    Jensen, Henrik; Brummerstedt Iversen, Steen; Joensen, Karsten Dan

    2006-01-01

    A novel method for producing crystalline nanosized metal oxides by a Supercritical Seed Enhanced Crystallization (SSEC) Process has been developed. The process is a modified sol-gel process taking place at temperatures as low as 95 ºC with supercritical CO2 as solvent and polypropylene as seeding...... material. The nanocrystalline product is obtained without having to resort to costly post-reaction processing and the product is obtained directly after the SSEC process. TiO2 powders produced by the SSEC process were shown to have a crystallinity of 60 % and a crystal size of 7.3 ± 2.6 nm....... The crystallinity can be controlled by changing the heating rate of the initial formation of the nanoparticles and the morphology can be altered by changing the process time....

  16. Composition dependence of crystallization temperature and magnetic property of NdFeB thin films

    Energy Technology Data Exchange (ETDEWEB)

    Khoa, T.V. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); International Training Institute for Materials Science (ITIMS), Hanoi University of Technology, 1 Dai Co Viet, Hanoi (Viet Nam); Ha, N.D. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Hong, S.M. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Jin, H.M. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Kim, G.W. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Hien, T.D. [International Training Institute for Materials Science (ITIMS), Hanoi University of Technology, 1 Dai Co Viet, Hanoi (Viet Nam); Tai, L.T. [International Training Institute for Materials Science (ITIMS), Hanoi University of Technology, 1 Dai Co Viet, Hanoi (Viet Nam); Duong, N.P. [International Training Institute for Materials Science (ITIMS), Hanoi University of Technology, 1 Dai Co Viet, Hanoi (Viet Nam); Lee, K.E. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Kim, C.G. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Kim, C.O. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of)]. E-mail: magkim@cnu.ac.kr

    2006-09-15

    Si(100)/Mo(30nm)/Nd{sub x}Fe{sub 92-x}B{sub 8}(800nm)/Mo(30nm) (x=14, 20, 30) films are prepared by RF magnetron sputtering at room temperature. As-deposited films are amorphous materials. The crystallization temperature of the Nd{sub 2}Fe{sub 14}B phase decreases from 575deg. C to 500deg. C with increase of x from 14 to 20-30. The optimum annealing temperature with 30min annealing time is 650 deg. C, 625 deg. C and 600 deg. C for x=14, 20 and 30, respectively, and the x=20 film has the largest energy product of 100118MG.

  17. Room-temperature ferromagnetism observed in C-/N-/O-implanted MgO single crystals

    Science.gov (United States)

    Li, Qiang; Ye, Bonian; Hao, Yingping; Liu, Jiandang; Zhang, Jie; Zhang, Lijuan; Kong, Wei; Weng, Huimin; Ye, Bangjiao

    2013-01-01

    MgO single crystals were implanted with 70 keV C/N/O ions at room temperature with respective doses of 2 × 1016 and 2 × 1017 ions/cm2. All samples with high-dose implantation showed room temperature hysteresis in magnetization loops. Magnetization and slow positron annihilation measurements confirmed that room temperature ferromagnetism in O-implanted samples was attributed to the presence of Mg vacancies. Furthermore, the introduction of C or N played more effective role in ferromagnetic performance than Mg vacancies. Moreover, the magnetic moment possibly occurred from the localized wave function of unpaired electrons and the exchange interaction formed a long-range magnetic order.

  18. Two-Dimensional Spatial Imaging of Charge Transport in Germanium Crystals at Cryogenic Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Moffatt, Robert [Stanford Univ., CA (United States)

    2016-03-01

    In this dissertation, I describe a novel apparatus for studying the transport of charge in semiconductors at cryogenic temperatures. The motivation to conduct this experiment originated from an asymmetry observed between the behavior of electrons and holes in the germanium detector crystals used by the Cryogenic Dark Matter Search (CDMS). This asymmetry is a consequence of the anisotropic propagation of electrons in germanium at cryogenic temperatures. To better model our detectors, we incorporated this effect into our Monte Carlo simulations of charge transport. The purpose of the experiment described in this dissertation is to test those models in detail. Our measurements have allowed us to discover a shortcoming in our most recent Monte Carlo simulations of electrons in germanium. This discovery would not have been possible without the measurement of the full, two-dimensional charge distribution, which our experimental apparatus has allowed for the first time at cryogenic temperatures.

  19. CH3NH3PbCl3 Single Crystals: Inverse Temperature Crystallization and Visible-Blind UV-Photodetector

    KAUST Repository

    Maculan, Giacomo

    2015-09-02

    Single crystals of hybrid perovskites have shown remarkably improved physical properties compared to their polycrystalline film counterparts, underscoring their importance in the further development of advanced semiconductor devices. Here we present a new method of sizeable CH3NH3PbCl3 single crystal growth based on retrograde solubility behavior of hybrid perovskites. We show, for the first time, the energy band structure, charge-carrier recombination and transport properties of single crystal CH3NH3PbCl3. The chloride-based perovskite crystals exhibit trap-state density, charge carriers concentration, mobility and diffusion length comparable with the best quality crystals of methylammonium lead iodide or bromide perovskites reported so far. The high quality of the crystal along with its suitable optical bandgap enabled us to design and build an efficient visible-blind UV-photodetector, demonstrating the potential of this material to be employed in optoelectronic applications.

  20. Effect of temperature on the luminescence of Sm{sup 3+} ions in YAM crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kaczkan, M. [Institute of Microelectronics and Optoelectronics PW, ul. Koszykowa 75, 00-662 Warsaw (Poland); Boruc, Z., E-mail: z.boruc@stud.elka.pw.edu.pl [Institute of Microelectronics and Optoelectronics PW, ul. Koszykowa 75, 00-662 Warsaw (Poland); Turczyński, S. [Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01-919 Warsaw (Poland); Malinowski, M. [Institute of Microelectronics and Optoelectronics PW, ul. Koszykowa 75, 00-662 Warsaw (Poland)

    2014-11-05

    Highlights: • Different concentration Sm{sup 3+}-doped Y{sub 4}Al{sub 2}O{sub 9} crystals are fabricated by μ-pulling down method. • Thermally activated {sup 4}F{sub 3/2} → {sup 6}H{sub 5/2} emission of Sm{sup 3+} in YAM is studied. • Temperature dependent quenching mechanism of the {sup 4}G{sub 5/2} luminescence is proposed. - Abstract: The spectroscopic features of samarium Sm{sup 3+} activated Y{sub 4}Al{sub 2}O{sub 9} (YAM) crystals are presented and discussed. Temperature sensing properties of Sm{sup 3+}:YAM phosphor was demonstrated over the 300–1200 K range. Temperature dependent luminescence spectra and decay curves for the {sup 4}G{sub 5/2} level of Sm{sup 3+} in YAM were measured. Ratio of the fluorescence intensities arising from the two close lying {sup 4}F{sub 3/2} and {sup 4}G{sub 5/2} levels (with energy separation of ΔE ∼ 1000 cm{sup −1}) followed a straight line pattern, which confirms the Boltzmann distribution of the population, and can be used to measure temperature. The lifetime for the {sup 4}G{sub 5/2} level in 1% Sm doped sample decreases from 1.65 to 0.08 ms with heating from room temperature to 1200 K. This behavior of decays is discussed in terms of radiative and multiphonon decays as well as cross-relaxation dependence on temperature.

  1. An algorythmic approach to restoration of the fronto-naso-periorbital skin defects using the forehead flaps.

    Science.gov (United States)

    Tan, Onder

    2010-01-01

    The classic forehead flaps, which are designed vertically, two-staged and exteriorised pedicled peninsular flaps, are still a reconstructive option for nasal and periorbital defects. However, some drawbacks such as conspicuous donor-site scar, multi-staged procedure, rather short pedicle, hairy appearance (in narrow foreheads), and inability to use the forehead flap when the donor site is involved are often encountered during surgery. To avoid these issues, three unusual designs of the forehead flap are presented, and also a new algorithm is proposed to guide surgeons in their solutions. Nineteen patients (10 women and nine men) were managed with 21 forehead flaps to restore the nasal, medial canthal and frontal defects caused by skin tumours. The flaps were applied as interpolation island, V-Y island, and transverse peninsular designs in 12, four and three patients, respectively. All donor sites were closed primarily except one, where a split thickness skin graft was used. The average follow-up was 14 months. All flaps survived (totally) but in one partial necrosis developed. Aesthetic and functional recoveries were acceptable in all patients. Based on the algorithm presented, the forehead flaps with their superb anatomic characteristics including rich vascular supply and pliable skin can be safely used in either classic or extraordinary fashion for small to medium sized defects of the nasoorbital and frontal regions.

  2. Effects of temperature and solvent concentration on the solvent crystallization of palm-based dihydroxystearic acid with isopropyl alcohol

    Institute of Scientific and Technical Information of China (English)

    Gregory F.L.Koay; Teong-Guan Chuah; Sumaiya Zainal-Abidin; Salmiah Ahmad; Thomas S.Y.Choong

    2012-01-01

    Palm-based dihydroxystearic acid of 69.55% purity was produced in a 500-kg-per-batch operation pilot plant and purified through solvent crystallization in a custom fabricated simultaneous batch crystallizer unit.The effects of temperature and solvent concentration on yield,particle size distribution and purity were studied.The purity was higher,while the yield and particle size were lower and smaller,respectively,at higher temperature and solvent concentration.The solvent crystallization process efficiency was rated at 66-69% when carried out with 70-80% isopropyl alcohol at 20 ℃.

  3. High-temperature Raman study of L-alanine, L-threonine and taurine crystals related to thermal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Cavaignac, A.L.O. [Centro de Ciências Sociais, Saúde e Tecnologia, Universidade Federal do Maranhão, Imperatriz, MA 65900-410 (Brazil); Lima, R.J.C., E-mail: ricardo.lima.ufma@gmail.com [Centro de Ciências Sociais, Saúde e Tecnologia, Universidade Federal do Maranhão, Imperatriz, MA 65900-410 (Brazil); Façanha Filho, P.F. [Centro de Ciências Sociais, Saúde e Tecnologia, Universidade Federal do Maranhão, Imperatriz, MA 65900-410 (Brazil); Moreno, A.J.D. [Coordenação de Ciências Naturais, Universidade Federal do Maranhão, Bacabal, MA 65700-000 (Brazil); Freire, P.T.C. [Departamento de Física, Universidade Federal do Ceará, Fortaleza, CE 60455-760 (Brazil)

    2016-03-01

    In this work high-temperature Raman spectra are used to compare temperature dependence of the lattice mode wavenumber of L-alanine, L-threonine and taurine crystals. Anharmonic effects observed are associated with intermolecular N-H· · ·O hydrogen bond that plays an important role in thermal decomposition process of these materials. Short and strong hydrogen bonds in L-alanine crystal were associated with anharmonic effects in lattice modes leading to low thermal stability compared to taurine crystals. Connection between thermal decomposition process and anharmonic effects is furnished for the first time.

  4. High-temperature Raman study of L-alanine, L-threonine and taurine crystals related to thermal decomposition

    International Nuclear Information System (INIS)

    Cavaignac, A.L.O.; Lima, R.J.C.; Façanha Filho, P.F.; Moreno, A.J.D.; Freire, P.T.C.

    2016-01-01

    In this work high-temperature Raman spectra are used to compare temperature dependence of the lattice mode wavenumber of L-alanine, L-threonine and taurine crystals. Anharmonic effects observed are associated with intermolecular N-H· · ·O hydrogen bond that plays an important role in thermal decomposition process of these materials. Short and strong hydrogen bonds in L-alanine crystal were associated with anharmonic effects in lattice modes leading to low thermal stability compared to taurine crystals. Connection between thermal decomposition process and anharmonic effects is furnished for the first time.

  5. Effect of temperature gradient and crystallization rate on morphological peculiarities of cellular-dendrite structure in iron-nickel alloys

    International Nuclear Information System (INIS)

    Kralina, A.A.; Vorontsov, V.B.

    1977-01-01

    Cellular and dendritic structure of Fe-Ni single crystals (31 and 45 wt%Ni) grown according to Bridgeman have been studied by metallography. Growth rates at which the crystallization frontier becomes unstable and splits into cells have been determined for three temperature gradients. The transition from cells to dendrites occurs gradually through the changes in the cells regular structure and formation of secondary and tertiary branches. The dependence of cell diameter and distance between dendrites on crystallization rate and temperature gradient are discussed in terms of the admixture substructures development according to the schedule: cells - cellular dendrites - dendrites

  6. Understanding size effects on the strength of single crystals through high-temperature micropillar compression

    International Nuclear Information System (INIS)

    Soler, Rafael; Wheeler, Jeffrey M.; Chang, Hyung-Jun; Segurado, Javier; Michler, Johann; Llorca, Javier; Molina-Aldareguia, Jon M.

    2014-01-01

    Compression tests of 〈1 1 1〉-oriented LiF single-crystal micropillars 1–5 μm in diameter were carried out from 25 °C to 250 °C. While the flow stress at ambient temperature was independent of the micropillar diameter, a strong size effect developed with elevated temperature. This behavior was explained by rigorously accounting for the different contributions to the flow stress of the micropillars as a function of temperature and pillar diameter: the lattice resistance, the forest hardening; and the size-dependent contribution as a result of the operation of single-arm dislocation sources. This was possible because the micropillars were obtained by chemically etching away the surrounding matrix in directionally solidified LiF–NaCl and LiF–KCl eutectics, avoiding any use of focused ion beam methods, yielding micropillars with a controlled dislocation density, independent of the sample preparation technique. In particular, the role of the lattice resistance on the size effect of micrometer-size single crystals was demonstrated unambiguously for the first time. This result rationalizes the different values of power-law exponent for the size effect found in the literature for face-centered cubic and body-centered cubic metals as well as for covalent and ionic solids

  7. Crystal structure and ionic conduction path of solid electrolytic materials by high temperature neutron diffraction method

    International Nuclear Information System (INIS)

    Yashima, Masatomo; Nomura, Katsuhiro

    2005-01-01

    Research of the distribution of oxide ions and the ionic conduction path of bismuth oxide (Bi 2 O 3 ), cerium oxide (CeO 2 ) and lanthanum gallate ((La 0.8 Sr 0.2 )(Ga 0.8 Mg 0.15 Co 0.05 )O 3-δ ) is stated. The high temperature neutron diffraction method, analytical method such as Rietveld method, crystal structure analysis of ionic conductor and MEM (Maximum- Entropy Method) are explained. The nuclear density distribution of oxide ions in bismuth oxide showed so larger distribution in the direction of and than Bi ions that the oxide ions conducted these direction in the crystal. The nuclear density distribution of oxide ions of cerium oxide indicated larger distribution in the direction of than Ce ions and its tendency was remarkable at high temperature. Accordingly, the oxide ions conducted in the direction of and . The oxide ions distribution in lanthanum gallate compound was larger and complicated than positive ions. The oxide ions conducted to by describing an arc between the two stable positions. The nuclear density on the conduction path increased with increasing temperature. This above result corresponded to increase of oxide ion conductivity in the area. (S.Y.)

  8. Filtering properties of Thue-Morse nano-photonic crystals containing high-temperature superconductor

    Science.gov (United States)

    Talebzadeh, Robabeh; Bavaghar, Mehrdad

    2018-05-01

    In this paper, we introduced new design of quasi-periodic layered structures by choosing order two of ternary Thue-Morse structure. We considered Superconductor-dielectric photonic crystal with mirror symmetric as (ABSSAB)N(BASSBA)N composed of two kinds of nano-scale dielectric layers (A and B) and high-temperature superconductor layers where N is the number of period. This structure is assumed to be the free space. By using the transfer matrix method and the two fluid model, we theoretically study the transmission spectrum of ternary Thue-Morse superconducting photonic crystals with mirror symmetry and introduce this structure as a narrow optical filter. We showed that transmission peak so-called defect mode appears itself inside the transmission spectrum of suggested structure as same as defective layered structure. Also, we analyzed the influence of various related parameters such as the operating temperature of superconductor layer on position of defect mode. The redshift of defect mode with increasing the operating temperature was observed.

  9. Temperature Dependent Surface Structures and Electronic Properties of Organic-Inorganic Hybrid Perovskite Single Crystals

    Science.gov (United States)

    Jao, M.-H.; Teague, M. L.; Huang, J.-S.; Tseng, W.-S.; Yeh, N.-C.

    Organic-inorganic hybrid perovskites, arising from research of low-cost high performance photovoltaics, have become promising materials not only for solar cells but also for various optoelectronic and spintronic applications. An interesting aspect of the hybrid perovskites is that their material properties, such as the band gap, can be easily tuned by varying the composition, temperature, and the crystalline phases. Additionally, the surface structure is critically important for their optoelectronic applications. It is speculated that different crystalline facets could show different trap densities, thus resulting in microscopically inhomogeneous performance. Here we report direct studies of the surface structures and electronic properties of hybrid perovskite CH3NH3PbI3 single crystals by scanning tunneling microscopy and spectroscopy (STM/STS). We found long-range spatially homogeneous tunneling conductance spectra with a well-defined energy gap of (1.55 +/- 0.1) eV at 300 K in the tetragonal phase, suggesting high quality of the single crystals. The energy gap increased to (1.81 +/- 0.1) eV in the orthorhombic phase, below the tetragonal-to-orthorhombic phase transition temperature at 150 K. Detailed studies of the temperature evolution in the spatially resolved surface structures and local density of states will be discussed to elucidate how these properties may influence the optoelectronic performance of the hybrid perovskites. We thank the support from NTU in Taiwan and from NSF in the US.

  10. The effects of moisture on LiD single crystals studied by temperature-programmed decomposition

    International Nuclear Information System (INIS)

    Dinh, L.N.; Cecala, C.M.; Leckey, J.H.; Balooch, M.

    2001-01-01

    Temperature-programmed decomposition (TPD) technique was performed on LiOH powders and LiD single crystals previously exposed to different moisture levels. Our results show that the LiOH decomposition process is rate-limited by an inward moving reaction front mechanism with an activation energy barrier of ∼122-149 kJ/mol. The LiOH structure is stable even if kept at 320 K. However, LiOH structures formed on the surface of LiD single crystals during moisture exposure at low dosages may have multiple activation energy barriers, some of which may be much lower than 122 kJ/mol. The rate-limiting mechanism for the decomposition of LiOH structures with reduced activation energy barriers is consistent with a unimolecular nucleation model. We attribute the lowering of the activation energy barrier for the LiOH decomposition to the existence of sub-stoichiometric Li(OH) x with x 2 O formation is observed. The release of H 2 O molecules from LiOH · H 2 O structure has small activation energy barriers in the range of 48-69 kJ/mol and follows a unimolecular nucleation process. The loosely bonded H 2 O molecules in the LiOH · H 2 O structure can be easily pumped away at room temperature in a reasonable amount of time. Our experiments also suggest that handling LiD single crystals at an elevated temperature of 340 K or more reduces the growth rate of LiOH and LiOH · H 2 O significantly

  11. Impact of growth temperature on the crystal habits, forms and structures of VO2 nanocrystals

    International Nuclear Information System (INIS)

    Loeffler, Stefan; Auer, Erwin; Lugstein, Alois; Bertagnolli, Emmerich; Weil, Matthias

    2011-01-01

    We investigated the impact of the process temperature on the habits, forms and crystal structure of VO 2 nanocrystals grown by a vapor-transport method on (0001) quartz substrates. Four distinct growth regimes were discerned: orthorhombic nanowires, sheets, hemispheres, and nanowires with a monoclinic structure. The nanostructures were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). I/V characterization of individual nanowires was enabled by Ti/Au contact formation via electron beam lithography and lift-off techniques. The expected metal-insulator transition (MIT) was found in monoclinic VO 2 nanowires. (orig.)

  12. A confocal optical microscope for detection of single impurities in a bulk crystal at cryogenic temperatures.

    Science.gov (United States)

    Karlsson, Jenny; Rippe, Lars; Kröll, Stefan

    2016-03-01

    A compact sample-scanning confocal optical microscope for detection of single impurities below the surface of a bulk crystal at cryogenic temperatures is described. The sample, lens, and scanners are mounted inside a helium bath cryostat and have a footprint of only 19 × 19 mm. Wide field imaging and confocal imaging using a Blu-ray lens immersed in liquid helium are demonstrated with excitation at 370 nm. A spatial resolution of 300 nm and a detection efficiency of 1.6% were achieved.

  13. High proton polarization at high temperature with single crystals of aromatic molecules

    International Nuclear Information System (INIS)

    Iinuma, M.; Takahashi, Y.; Shake, I.; Oda, M.; Masaike, A.; Yabuzaki, T.; Shimizu, H.M.

    2004-01-01

    Protons in single crystals of naphthalene doped with pentacene and p-terphenyl doped with pentacene have been polarized up to 32% and 18%, respectively. Such polarization has been achieved at liquid nitrogen temperature in a magnetic field of 3 kG by means of microwave-induced optical nuclear polarization. We also measured the polarization by the neutron transmission method. The relaxation time at 77 K in 7 G was found to be about 3 h and the enhancement of the obtained polarization compared with thermal polarization reached 8x10 4 . This method is applicable to neutron experiments

  14. CH3NH3PbCl3 Single Crystals: Inverse Temperature Crystallization and Visible-Blind UV-Photodetector

    KAUST Repository

    Maculan, Giacomo; Sheikh, Arif D.; Abdelhady, Ahmed L.; Saidaminov, Makhsud I.; Haque, Mohammed; Banavoth, Murali; Alarousu, Erkki; Mohammed, Omar F.; Wu, Tao; Bakr, Osman

    2015-01-01

    a new method of sizeable CH3NH3PbCl3 single crystal growth based on retrograde solubility behavior of hybrid perovskites. We show, for the first time, the energy band structure, charge-carrier recombination and transport properties of single crystal

  15. Reconfigurable Photonic Crystals Enabled by Multistimuli-Responsive Shape Memory Polymers Possessing Room Temperature Shape Processability.

    Science.gov (United States)

    Fang, Yin; Leo, Sin-Yen; Ni, Yongliang; Wang, Junyu; Wang, Bingchen; Yu, Long; Dong, Zhe; Dai, Yuqiong; Basile, Vito; Taylor, Curtis; Jiang, Peng

    2017-02-15

    Traditional shape memory polymers (SMPs) are mostly thermoresponsive, and their applications in nano-optics are hindered by heat-demanding programming and recovery processes. By integrating a polyurethane-based shape memory copolymer with templating nanofabrication, reconfigurable/rewritable macroporous photonic crystals have been demonstrated. This SMP coupled with the unique macroporous structure enables unusual all-room-temperature shape memory cycles. "Cold" programming involving microscopic order-disorder transitions of the templated macropores is achieved by mechanically deforming the macroporous SMP membranes. The rapid recovery of the permanent, highly ordered photonic crystal structure from the temporary, disordered configuration can be triggered by multiple stimuli including a large variety of vapors and solvents, heat, and microwave radiation. Importantly, the striking chromogenic effects associated with these athermal and thermal processes render a sensitive and noninvasive optical methodology for quantitatively characterizing the intriguing nanoscopic shape memory effects. Some critical parameters/mechanisms that could significantly affect the final performance of SMP-based reconfigurable photonic crystals including strain recovery ratio, dynamics and reversibility of shape recovery, as well as capillary condensation of vapors in macropores, which play a crucial role in vapor-triggered recovery, can be evaluated using this new optical technology.

  16. The Low-Temperature Crystallization and Interface Characteristics of ZnInSnO/In Films Using a Bias-Crystallization Mechanism

    International Nuclear Information System (INIS)

    Chen, K. J.; Chen, K.J.; Hung, F.Y.; Lui, T.S.; Chang, S.J.; Hu, Z.S.

    2012-01-01

    This study presents a successful bias crystallization mechanism (BCM) based on an indium/glass substrate and applies it to fabrication of ZnInSnO (ZITO) transparent conductive oxide (TCO) films. The effects of bias-crystallization on electrical and structural properties of ZITO/In structure indicate that the current-induced Joule heating and interface diffusion were critical factors for low-temperature crystallization. With biases of 4 V and 0.1 A, the resistivity of the ZITO film was reduced from 3.08x10 -4 Ω * cm to 6.3x10 -5 Ω * cm. This reduction was attributed to the bias-induced energy, which caused indium atoms to diffuse into the ZITO matrix. This effectuated crystallizing the amorphous ZITO (a-ZITO) matrix at a lower temperature (approximately 170 degree C) for a short period (≤20 min) during a bias test. The low-temperature BCM developed for this study obtained an efficient conventional annealed treatment (higher temperature), possessed energy-saving and speed advantages, and can be considered a candidate for application in photoelectric industries.

  17. Low-temperature embrittlement and fracture of metals with different crystal lattices – Dislocation mechanisms

    Directory of Open Access Journals (Sweden)

    V.M. Chernov

    2016-12-01

    Full Text Available The state of a low-temperature embrittlement (cold brittleness and dislocation mechanisms for formation of the temperature of a ductile-brittle transition and brittle fracture of metals (mono- and polycrystals with various crystal lattices (BCC, FCC, HCP are considered. The conditions for their formation connected with a stress-deformed state and strength (low temperature yield strength as well as the fracture breaking stress and mobility of dislocations in the top of a crack of the fractured metal are determined. These conditions can be met for BCC and some HCP metals in the initial state (without irradiation and after a low-temperature damaging (neutron irradiation. These conditions are not met for FCC and many HCP metals. In the process of the damaging (neutron irradiation such conditions are not met also and the state of low-temperature embrittlement of metals is absent (suppressed due to arising various radiation dynamic processes, which increase the mobility of dislocations and worsen the strength characteristics.

  18. Temperature dependence of volume thermal expansion for NaCl and KCl crystals

    International Nuclear Information System (INIS)

    Fang Zhenghua

    2005-01-01

    A new relation for predicting volume thermal expansion of alkali halides at high temperatures is derived based on the assumption that the two different diffusional driving force models presented, respectively, by Sharma and Sharma (Indian J. Pure Appl. Phys. 29 (1991) 637) and Singh (J. Phys. Chem. Solids 63 (2002) 1935) are equivalent. The input parameters needed for the calculation are the volume thermal expansion coefficient and the isothermal Anderson-Gruneisen parameter, both at room temperature and zero pressure, which are available from the literature. The tests on NaCl and KCl crystals demonstrate that the agreement between the calculated results obtained by this relation and the corresponding experimental data is very good. The applicability of the relation as well as some thermodynamic relationships included in its derivation is discussed

  19. The significance of temperature dependence on the piezoelectric energy harvesting by using a phononic crystal

    Science.gov (United States)

    Aly, Arafa H.; Nagaty, Ahmed; Khalifa, Zaki; Mehaney, Ahmed

    2018-05-01

    In this study, an acoustic energy harvester based on a two-dimensional phononic crystal has been constructed. The present structure consists of silicon cylinders in the air background with a polyvinylidene fluoride cylinder as a defect to confine the acoustic energy. The presented energy harvester depends on the piezoelectric effect (using the piezoelectric material polyvinylidene fluoride) that converts the confined acoustic energy to electric energy. The maximum output voltage obtained equals 170 mV. Moreover, the results revealed that the output voltage can be increased with increasing temperature. In addition, the effects of the load resistance and the geometry of the piezoelectric material on the output voltage have been studied theoretically. Based on these results, all previous studies about energy harvesting in phononic structures must take temperature effects into account.

  20. Investigation into the temperature dependence of isotropic- nematic phase transition of Gay- Berne liquid crystals

    Directory of Open Access Journals (Sweden)

    A Avazpour

    2014-12-01

    Full Text Available Density functional approach was used to study the isotropic- nematic (I-N transition and calculate the values of freezing parameters of the Gay- Berne liquid crystal model. New direct and pair correlation functions of a molecular fluid with Gay- Berne pair potential were used. These new functions were used in density functional theory as input to calculate the isotropic- nematic transition densities for elongation at various reduced temperatures. It was observed that the isotropic- nematic transition densities increase as the temperature increases. It was found that the new direct correlation function is suitable to study the isotropic- nematic transition of Gay- Berne liquids. Comparison to other works showed qualitative agreement

  1. Reduction of crystallization temperature of the Nd-Fe-B thin films by Cu addition

    International Nuclear Information System (INIS)

    Ma Yungui; Yang Zheng; Matsumoto, M.; Morisako, A.; Takei, S.

    2004-01-01

    Nonmagnetic Cu element has been doped into the sputtered Nd-Fe-B thin films. It is found that the introduction of suitable amount of copper atoms could reduce the crystallization temperature of the 2:14:1 phase by near 100 deg. C, compared with that without Cu. For the 15 nm Nd 16 Fe 70.2 Cu 1.8 B 12 film deposited at 340 deg. C, perpendicular coercivity and remanent magnetization ratio of 350 kA/m and 0.96 have been successfully obtained. Cu addition would lead to the grain growth, but the average grain size in the films could be greatly decreased through lowering the deposition temperature. These results are compared with those found in the fabrication of FePtCu films

  2. Hydrothermal temperature effect on crystal structures, optical properties and electrical conductivity of ZnO nanostructures

    Science.gov (United States)

    Dhafina, Wan Almaz; Salleh, Hasiah; Daud, Mohd Zalani; Ghazali, Mohd Sabri Mohd; Ghazali, Salmah Mohd

    2017-09-01

    ZnO is an wide direct band gap semiconductor and possess rich family of nanostructures which turned to be a key role in the nanotechnology field of applications. Hydrothermal method was proven to be simple, robust and low cost among the reported methods to synthesize ZnO nanostructures. In this work, the properties of ZnO nanostructures were altered by varying temperatures of hydrothermal process. The changes in term of morphological, crystal structures, optical properties and electrical conductivity were investigated. A drastic change of ZnO nanostructures morphology and decreases of 002 diffraction peak were observed as the hydrothermal temperature increased. The band gap of samples decreased as the size of ZnO nanostructure increased, whereas the electrical conductivity had no influence on the band gap value but more on the morphology of ZnO nanostructures instead.

  3. Diffraction and single-crystal elastic constants of Inconel 625 at room and elevated temperatures determined by neutron diffraction

    International Nuclear Information System (INIS)

    Wang, Zhuqing; Stoica, Alexandru D.; Ma, Dong; Beese, Allison M.

    2016-01-01

    In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.

  4. Diffraction and single-crystal elastic constants of Inconel 625 at room and elevated temperatures determined by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhuqing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Stoica, Alexandru D. [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Ma, Dong, E-mail: dongma@ornl.gov [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Beese, Allison M., E-mail: amb961@psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

    2016-09-30

    In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.

  5. Reduce synthesis temperature and improve dispersion of YAG nanopowders based on the co-crystallization method

    Energy Technology Data Exchange (ETDEWEB)

    Fan, G.F.; Tang, Y.Q.; Lu, W.Z., E-mail: lwz@mail.hust.edu.cn; Zhang, X.R.; Xu, X.

    2015-01-05

    Highlights: • YAG nanopowders were synthesized through a co-crystallization method. • A three-layer core–shell structure was made to lower the synthesis temperature. • PAA again reduced the synthesis temperature based on the core–shell structure. • YAG nanopowders were synthesized at 700 °C in normal apparatus. • Agglomeration was greatly improved by PAA. - Abstract: Pure yttrium aluminum garnet (YAG) nanopowders were synthesized at 950 °C from the co-crystallization precursor of Y(NO{sub 3}){sub 3}⋅6H{sub 2}O and Al(NO{sub 3}){sub 3}⋅9H{sub 2}O (nitrate process). When 17 wt.% of Y(NO{sub 3}){sub 3}⋅6H{sub 2}O was replaced by Y{sub 2}O{sub 3} nanopowders, so as to make up a three-layer core–shell structure of the precursor, the synthesis temperature was reduced to 850 °C (Y{sub 2}O{sub 3} process). Based on Y{sub 2}O{sub 3} process, further reducing the synthesis temperature to 700 °C was realized by adding polyacrylic acid (PAA, 50% M), which was used to shorten the distance of the metal ions and provide combustion heat (PAA process). TEM characterizations indicated that the powders produced through nitrate and Y{sub 2}O{sub 3} processes agglomerated, while the powders produced through PAA process were dispersed much better. The agglomerate size analysis results demonstrated that the powders produced through PAA process were with smaller agglomerate size and wider agglomerate size distribution than those through nitrate process or Y{sub 2}O{sub 3} process. And they were more likely to be sintered to YAG transparent ceramics.

  6. Temperature- and excitation intensity-dependent photoluminescence in TlInSeS single crystals

    International Nuclear Information System (INIS)

    Gasanly, N M; Aydinli, A; Yuksek, N S

    2002-01-01

    Photoluminescence (PL) spectra of TlInSeS layered single crystals were investigated in the wavelength region 460-800 nm and in the temperature range 10-65 K. We observed one wide PL band centred at 584 nm (2.122 eV) at T=10 K and an excitation intensity of 7.5 W cm -2 . We have also studied the variation of the PL intensity versus excitation laser intensity in the range from 0.023 to 7.5 W cm -2 . The red shift of this band with increasing temperature and blue shift with increasing laser excitation intensity was observed. The PL was found to be due to radiative transitions from the moderately deep donor level located at 0.243 eV below the bottom of the conduction band to the shallow acceptor level at 0.023 eV located above the top of the valence band. The proposed energy-level diagram permits us to interpret the recombination processes in TlInSeS layered single crystals

  7. Influence of the atomic structure of crystal surfaces on the surface diffusion in medium temperature range

    International Nuclear Information System (INIS)

    Cousty, J.P.

    1981-12-01

    In this work, we have studied the influence of atomic structure of crystal surface on surface self-diffusion in the medium temperature range. Two ways are followed. First, we have measured, using a radiotracer method, the self-diffusion coefficient at 820 K (0.6 T melting) on copper surfaces both the structure and the cleanliness of which were stable during the experiment. We have shown that the interaction between mobile surface defects and steps can be studied through measurements of the anisotropy of surface self diffusion. Second, the behavior of an adatom and a surface vacancy is simulated via a molecular dynamics method, on several surfaces of a Lennard Jones crystal. An inventory of possible migration mechanisms of these surface defects has been drawn between 0.35 and 0.45 Tsub(m). The results obtained with both the methods point out the influence of the surface atomic structure in surface self-diffusion in the medium temperature range [fr

  8. Temperature- and excitation intensity-dependent photoluminescence in TlInSeS single crystals

    CERN Document Server

    Gasanly, N M; Yuksek, N S

    2002-01-01

    Photoluminescence (PL) spectra of TlInSeS layered single crystals were investigated in the wavelength region 460-800 nm and in the temperature range 10-65 K. We observed one wide PL band centred at 584 nm (2.122 eV) at T=10 K and an excitation intensity of 7.5 W cm sup - sup 2. We have also studied the variation of the PL intensity versus excitation laser intensity in the range from 0.023 to 7.5 W cm sup - sup 2. The red shift of this band with increasing temperature and blue shift with increasing laser excitation intensity was observed. The PL was found to be due to radiative transitions from the moderately deep donor level located at 0.243 eV below the bottom of the conduction band to the shallow acceptor level at 0.023 eV located above the top of the valence band. The proposed energy-level diagram permits us to interpret the recombination processes in TlInSeS layered single crystals.

  9. Optical properties of CsI single crystals irradiated with neutrons at low temperature

    International Nuclear Information System (INIS)

    Okada, M.; Atobe, K.; Itatani, N.; Ozawa, K.

    1998-01-01

    Optical properties of the irradiation-induced-defects in neutron-irradiated CsI single crystals have been investigated. The nominally pure CsI crystals are irradiated by reactor fast neutrons (E>0.1 MeV) with a fluence of 1.4 x 10 15 n/cm 2 at 20 K and by γ-rays from 60 Co source to a dose of 1.5 x 10 4 Gy at liquid nitrogen temperature (LNT). After the irradiations, isochronal annealings are performed to investigate the thermal behavior of the defects. The glow peaks of the thermoluminescence (TL) in each sample irradiated with neutrons at 20 K and with γ-rays at LNT are observed at about 100, 160 and 220 K. In the neutron-irradiated samples at 20 K, the emission band at 338 nm is observed at LNT. It is supposed that this emission band occurs by an excitation of γ-rays from 134 Cs, which is radioactivated by thermal neutrons among the reactor radiations. It is confirmed that the temperature dependence of the 338 nm band is similar with that of the emission band due to the self-trapped exciton which is introduced into the non-irradiated samples illuminated by higher energy photons. (orig.)

  10. Optical properties of CsI single crystals irradiated with neutrons at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Okada, M. [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.; Nakagawa, M. [Faculty of Education, Kagawa Univ., Takamatsu, Kagawa (Japan); Atobe, K. [Faculty of Science, Naruto Univ. of Education, Naruto, Tokushima (Japan); Itatani, N.; Ozawa, K. [Horiba Ltd., Minamiku, Kyoto (Japan)

    1998-05-01

    Optical properties of the irradiation-induced-defects in neutron-irradiated CsI single crystals have been investigated. The nominally pure CsI crystals are irradiated by reactor fast neutrons (E>0.1 MeV) with a fluence of 1.4 x 10{sup 15} n/cm{sup 2} at 20 K and by {gamma}-rays from {sup 60}Co source to a dose of 1.5 x 10{sup 4} Gy at liquid nitrogen temperature (LNT). After the irradiations, isochronal annealings are performed to investigate the thermal behavior of the defects. The glow peaks of the thermoluminescence (TL) in each sample irradiated with neutrons at 20 K and with {gamma}-rays at LNT are observed at about 100, 160 and 220 K. In the neutron-irradiated samples at 20 K, the emission band at 338 nm is observed at LNT. It is supposed that this emission band occurs by an excitation of {gamma}-rays from {sup 134}Cs, which is radioactivated by thermal neutrons among the reactor radiations. It is confirmed that the temperature dependence of the 338 nm band is similar with that of the emission band due to the self-trapped exciton which is introduced into the non-irradiated samples illuminated by higher energy photons. (orig.) 13 refs.

  11. On the behavior of water at subfreezing temperatures in a protein crystal: evidence of higher mobility than in bulk water.

    Science.gov (United States)

    Wang, Dongqi; Böckmann, Anja; Dolenc, Jožica; Meier, Beat H; van Gunsteren, Wilfred F

    2013-10-03

    NMR experiments have shown that water molecules in the crystal of the protein Crh are still mobile at temperatures well below 273 K. In order to investigate this water anomaly, a molecular dynamics (MD) simulation study of crystalline Crh was carried out to determine the mobility of water in this crystal. The simulations were carried out at three temperatures, 150, 200, and 291 K. Simulations of bulk water at these temperatures were also done to obtain the properties of the simple point charge (SPC) water model used at these temperatures and to allow a comparison of the properties of water in the Crh crystal with those of bulk water at the same temperatures. According to the simulations, water is immobilized at 150 K both in crystal and in bulk water. As expected, at 291 K it diffuses and rotates more slowly in the protein crystal than in bulk water. However, at 200 K, the translational and rotational mobility of the water molecules is larger in the crystal than in bulk water. The enhancement of water mobility in the crystal at 200 K was further investigated by MD simulations in which the backbone or all protein atoms were positionally restrained, and in which additionally the electrostatic protein-water interactions were removed. Of these changes in the environment of the water molecules, rigidifying the protein backbones slightly enhanced water diffusion, while it slowed down rotation. In contrast, removal of electrostatic protein-water interactions did not change water diffusion but enhanced rotational motion significantly. Further investigations are required to delineate particular features of the protein crystal that induce the anomalous behavior of water at 200 K.

  12. The Mobility Enhancement of Indium Gallium Zinc Oxide Transistors via Low-temperature Crystallization using a Tantalum Catalytic Layer.

    Science.gov (United States)

    Shin, Yeonwoo; Kim, Sang Tae; Kim, Kuntae; Kim, Mi Young; Oh, Saeroonter; Jeong, Jae Kyeong

    2017-09-07

    High-mobility indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) are achieved through low-temperature crystallization enabled via a reaction with a transition metal catalytic layer. For conventional amorphous IGZO TFTs, the active layer crystallizes at thermal annealing temperatures of 600 °C or higher, which is not suitable for displays using a glass substrate. The crystallization temperature is reduced when in contact with a Ta layer, where partial crystallization at the IGZO back-channel occurs with annealing at 300 °C, while complete crystallization of the active layer occurs at 400 °C. The field-effect mobility is significantly boosted to 54.0 cm 2 /V·s for the IGZO device with a metal-induced polycrystalline channel formed at 300 °C compared to 18.1 cm 2 /V·s for an amorphous IGZO TFT without a catalytic layer. This work proposes a facile and effective route to enhance device performance by crystallizing the IGZO layer with standard annealing temperatures, without the introduction of expensive laser irradiation processes.

  13. Temperature Compensated Strain Sensor Based on Cascaded Sagnac Interferometers and All-Solid Birefringent Hybrid Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Gu, Bobo; Yuan, Wu; He, Sailing

    2012-01-01

    We demonstrate a temperature compensated strain sensor with two cascaded Sagnac interferometers, that provide strain sensing and temperature compensation, respectively. The Sagnac interferometers use an all-solid hybrid photonic crystal fiber with stress-induced birefringence. The stress-induced ...

  14. Experimental and numerical study of the high-temperature structure of copper single crystal surfaces

    International Nuclear Information System (INIS)

    Loisel, Bertrand

    1989-01-01

    The structure of copper single crystal surfaces has been investigated on an atomic scale using two complementary tools: helium beam diffraction experiments and computer simulations by molecular dynamics. In the case of stepped surfaces, the roughening transition occurs at low temperature. Our helium beam diffraction experiments in the range 70-1000 K reveal this transition at 650±50 K and 150±50 K respectively on the (331) and (310) surfaces. We emphasize the role of the terrace and step structure on the thermal roughness, which is ruled by microscopic energies related to the creation and interaction of defects on the step edges. Adsorbing oxygen on a rough (310) surface gives rise to ordered superstructures. In our computer simulations, the interatomic forces are derived from an empiric N-body potential which leads to a realistic description of the static and dynamical properties of the bulk metal and its surfaces. We analyze the results of high-temperature simulations on the (110) surface. Two types of disorder are distinguished: the creation of adatom-vacancy pairs and the enhancement of the vibrational amplitudes of the atoms near their equilibrium site. We establish that both phenomena take place in the same temperature range. These simulations also indicate the very anisotropic behaviour of the surface at high temperatures (> 1000 K). (author) [fr

  15. Near-infrared refractive index of synthetic single crystal and polycrystalline diamonds at high temperatures

    Science.gov (United States)

    Yurov, V. Yu.; Bushuev, E. V.; Popovich, A. F.; Bolshakov, A. P.; Ashkinazi, E. E.; Ralchenko, V. G.

    2017-12-01

    We measured the refractive index n(T) and thermo-optical coefficient β(T) = (1/n)(dn/dT) of high quality synthetic diamonds from room temperature to high temperatures, up to 1520 K, in near-infrared spectral range at wavelength 1.56 μm, using a low-coherence interferometry. A type IIa single crystal diamond produced by high pressure-high temperature technique and a transparent polycrystalline diamond grown by chemical vapor deposition were tested and revealed a very close n(T) behavior, with n = 2.384 ± 0.001 at T = 300 K, monotonically increasing to 2.428 at 1520 K. The n(T) data corrected to thermal expansion of diamond are well fitted with 3rd order polynomials, and alternatively, with the Bose-Einstein model with an effective oscillator frequency of 970 cm-1. Almost linear n(T) dependence is observed above 800 K. The thermo-optical coefficient is found to increase monotonically from (0.6 ± 0.1) × 10-5 K-1 (300 K) to (2.0 ± 0.1) × 10-5 K-1 (1300 K) with a tendency to saturation at >1200 K. These β(T) values are an order of magnitude lower than those known for Si, GaAs, and InP. The obtained results significantly extend the temperature range, where the refractive index of diamond was previously measured.

  16. Effect of high temperature annealing on defects and optical properties of ZnO single crystals

    International Nuclear Information System (INIS)

    Jiang, M.; Wang, D.D.; Zou, B.; Chen, Z.Q.; Kawasuso, A.; Sekiguchi, T.

    2012-01-01

    Hydrothermal grown ZnO single crystals were annealed in N 2 or O 2 between 900 and 1300 C. Positron lifetime measurements reveal a single lifetime in all the ZnO samples before and after annealing. The positron lifetime is about 181 ps after annealing at 900 C in either N 2 or O 2 atmosphere. However, increase of the positron lifetime is observed after further annealing the sample at higher temperatures up to 1300 C, and it has a faster increase in O 2 ambient. Temperature dependence measurements show that the positron lifetime has very slight increase with temperature for the 900 C annealed sample, while it shows notable variation for the sample annealed at 1300 C. This implied that annealing at high temperature introduces additional defects. These defects are supposed to be Zn vacancy-related defects. Cathodoluminescence (CL) measurements indicates enhancement of both UV and green emission after annealing, and the enhancement of green emission is much stronger for the samples annealed in O 2 ambient. The possible origin of green emission is tentatively discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Temperature and strain-rate dependence of the flow stress of ultrapure tantalum single crystals

    International Nuclear Information System (INIS)

    Werner, M.

    1987-01-01

    Measurements of the temperature dependence of the cyclic flow stress of ultrapure tantalum single crystals (RRR >∼ 14000) are extended to lower temperatures. After cyclic deformation well into saturation at 400 K, the temperature dependence of the flow stress is measured between 80 and 450 K at five different plastic resolved shear-strain rates, ε pl , in the range 2 x 10 -5 to 6 x 10 -3 s -1 . Below a critical temperature T k the flow stress is dominantly controlled by the mobility of screw dislocations. A recent theory of Seeger describes the 'thermal' component, σ*, of the flow stress (resolved shear stress) in the temperature and stress regime where the strain rate is determined by the formation and migration of kink pairs. The analytical expressions are valid in well-defined ranges of stress and temperature. The evaluation of the experimental data yields a value for the formation enthalpy of two isolated kinks 2H k = 0.98 eV. From the low-stress (σ* k = 2.0 x 10 -6 m 2 s -1 . The product of the density of mobile screw dislocations and the distance between insurmountable obstacles is found to be 2 x 10 -5 m -1 . The stress dependence of the kink-pair formation enthalpy H kp follows the theoretically predicted curve in the elastic-interaction stress regime. At the transition to the line-tension approximation (near σ* ∼ 80 MPa) the activation volume increases rather abruptly. Moreover, the quantitative analysis involves kinks other than those of minimum height. The most likely candidates are kinks on {211} planes. (author)

  18. Temperature-dependent ordering phenomena in single crystals of germanium antimony tellurides

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Philipp [Faculty of Chemistry and Mineralogy, Leipzig University, Scharnhorststr. 20, 04275 Leipzig (Germany); Schneider, Matthias N. [Department of Chemistry, LMU Munich, Butenandtstr. 5-13 (D), 81377 Munich (Germany); Oeckler, Oliver, E-mail: oliver.oeckler@gmx.de [Faculty of Chemistry and Mineralogy, Leipzig University, Scharnhorststr. 20, 04275 Leipzig (Germany)

    2015-07-15

    The temperature-dependent behavior of quenched single-crystalline (GeTe){sub n}Sb{sub 2}Te{sub 3} (n~2.8, n~5 and n~11) was investigated by semiquantitative modeling of diffuse X-ray scattering. The structure at room temperature exhibits trigonal twin domains, each comprising a stacking-disordered sequence of distorted rocksalt-type slabs with variable thicknesses. Ge and Sb share the cation position and vacancies are partially ordered in defect layers (van der Waals gaps) between the slabs. The average structure determined with resonant diffraction data corresponds to a rocksalt-type structure whose cation position is split along the stacking direction. Upon heating, cation ordering leads to a metastable superstructure of the rocksalt type at ~400 °C, which transforms to a rocksalt-type high-temperature phase with randomly distributed cations and vacancies at ~500 °C; this structure was also refined using resonant diffraction. Cooling at high or intermediate rates does not yield the long-range ordered phase, but directly leads to the twinned disordered phase. - Graphical abstract: Development of the diffraction patterns of (GeTe){sub ~11}Sb{sub 2}Te{sub 3} upon heating; the insets symbolically sketch the real structure at the corresponding temperatures. - Highlights: • The structure of disordered (GeTe){sub n}Sb{sub 2}Te{sub 3} is described as a function of temperature. • Structural changes are tracked by modeling diffuse X-ray scattering. • Quenched crystals exhibit distorted NaCl-type slabs with different thicknesses. • Vacancy ordering upon heating leads to a metastable superstructure of the NaCl type. • Further heating leads to an undistorted disordered NaCl-type high-temperature phase.

  19. Accurate dew-point measurement over a wide temperature range using a quartz crystal microbalance dew-point sensor

    Science.gov (United States)

    Kwon, Su-Yong; Kim, Jong-Chul; Choi, Buyng-Il

    2008-11-01

    Quartz crystal microbalance (QCM) dew-point sensors are based on frequency measurement, and so have fast response time, high sensitivity and high accuracy. Recently, we have reported that they have the very convenient attribute of being able to distinguish between supercooled dew and frost from a single scan through the resonant frequency of the quartz resonator as a function of the temperature. In addition to these advantages, by using three different types of heat sinks, we have developed a QCM dew/frost-point sensor with a very wide working temperature range (-90 °C to 15 °C). The temperature of the quartz surface can be obtained effectively by measuring the temperature of the quartz crystal holder and using temperature compensation curves (which showed a high level of repeatability and reproducibility). The measured dew/frost points showed very good agreement with reference values and were within ±0.1 °C over the whole temperature range.

  20. Room temperature synthesis of silver nanowires from tabular silver bromide crystals in the presence of gelatin

    Science.gov (United States)

    Liu, Suwen; Wehmschulte, Rudolf J.; Lian, Guoda; Burba, Christopher M.

    2006-03-01

    Long silver nanowires were synthesized at room temperature by a simple and fast process derived from the development of photographic films. A film consisting of an emulsion of tabular silver bromide grains in gelatin was treated with a photographic developer (4-(methylamino)phenol sulfate (metol), citric acid) in the presence of additional aqueous silver nitrate. The silver nanowires have lengths of more than 50 μm, some even more than 100 μm, and average diameters of about 80 nm. Approximately, 70% of the metallic silver formed in the reduction consists of silver nanowires. Selected area electron diffraction (SAED) results indicate that the silver nanowires grow along the [111] direction. It was found that the presence of gelatin, tabular silver bromide crystals and silver ions in solution are essential for the formation of the silver nanowires. The nanowires appear to originate from the edges of the silver bromide crystals. They were characterized by transmission electron microscopy (TEM), SAED, scanning electron microscopy (SEM), and powder X-ray diffraction (XRD).

  1. Room temperature synthesis of silver nanowires from tabular silver bromide crystals in the presence of gelatin

    International Nuclear Information System (INIS)

    Liu Suwen; Wehmschulte, Rudolf J.; Lian Guoda; Burba, Christopher M.

    2006-01-01

    Long silver nanowires were synthesized at room temperature by a simple and fast process derived from the development of photographic films. A film consisting of an emulsion of tabular silver bromide grains in gelatin was treated with a photographic developer (4-(methylamino)phenol sulfate (metol), citric acid) in the presence of additional aqueous silver nitrate. The silver nanowires have lengths of more than 50 μm, some even more than 100 μm, and average diameters of about 80 nm. Approximately, 70% of the metallic silver formed in the reduction consists of silver nanowires. Selected area electron diffraction (SAED) results indicate that the silver nanowires grow along the [111] direction. It was found that the presence of gelatin, tabular silver bromide crystals and silver ions in solution are essential for the formation of the silver nanowires. The nanowires appear to originate from the edges of the silver bromide crystals. They were characterized by transmission electron microscopy (TEM), SAED, scanning electron microscopy (SEM), and powder X-ray diffraction (XRD)

  2. Room temperature X- and gamma-ray detectors using thallium bromide crystals

    CERN Document Server

    Hitomi, K; Shoji, T; Suehiro, T; Hiratate, Y

    1999-01-01

    Thallium bromide (TlBr) is a compound semiconductor with wide band gap (2.68 eV) and high X- and gamma-ray stopping power. The TlBr crystals were grown by the horizontal travelling molten zone (TMZ) method using purified material. Two types of room temperature X- and gamma-ray detectors were fabricated from the TlBr crystals: TlBr detectors with high detection efficiency for positron annihilation gamma-ray (511 keV) detection and TlBr detectors with high-energy resolution for low-energy X-ray detection. The detector of the former type demonstrated energy resolution of 56 keV FWHM (11%) for 511 keV gamma-rays. Energy resolution of 1.81 keV FWHM for 5.9 keV was obtained from the detector of the latter type. In order to analyze noise characteristics of the detector-preamplifier assembly, the equivalent noise charge (ENC) was measured as a function of the amplifier shaping time for the high-resolution detector. This analysis shows that parallel white noise and 1/f noise were dominant noise sources in the detector...

  3. Painless lump over the forehead which turned painful: an unusual presentation of hepatocellular carcinoma

    Directory of Open Access Journals (Sweden)

    S P Susheela

    2015-05-01

    Full Text Available Hepatocellular carcinoma (HCC is one of the most common malignancies and is known to most often present with symptomatology pertaining to local hepatic disease. Although HCC is known to metastasize to lungs, abdominal lymph nodes, adrenal glands and the vertebral column, it is rather rare to come across patients with skull metastasis. The manifestation of a solitary frontal bone metastasis leading to a painless lump over the forehead as the initial presenting feature of HCC is highly unusual. This case report pertains to a 40-year-old male patient who had initially observed a painless lump over his forehead that was gradually increasing in size over a span of 3 months. He sought medical attention when, after several months, the "painless lump" suddenly became painful. Investigations revealed the involvement of both the outer and the inner table of the frontal bone, and a biopsy revealed the histopathology to be that of HCC. On further investigation, he was found to have systemic disseminated disease involving both the left and right lungs and vertebrae and treatment was initiated with sorafenib. Despite an initial partial response, the patient subsequently succumbed to hepatic failure. This case report illustrates the fact that HCC can silently progress, and even lead to dissemination and distant metastases before becoming clinically evident.

  4. [Acute epidural hematoma of the posterior fossa caused by forehead impact].

    Science.gov (United States)

    Abe, S; Furukawa, K; Endo, S; Hoshi, S; Kanaya, H

    1988-03-01

    A rare case of acute epidural hematoma of the posterior fossa caused by forehead impact is reported. This 36-year-old man fell from a truck and hit his face. He was conscious and was brought to our center 30 minutes after the injury. On admission, a contused wound of the right forehead was noticed. He was restless and had severe pain in the neck and upper extremities. Skull X-ray showed a linear fracture of the frontal bone and computed tomography (CT) scan was normal. He continued to be restless and sudden respiratory arrest and pupillary dilation occurred 10 hours after the admission. A CT scan revealed a lenticular high density area in the left posterior fossa which extended to the supratentorial region. The 4th ventricle was compressed and displaced to the right and also the quadrigeminal and ambient cisterns were not visualized at all. Immediate surgery disclosed a 30 g epidural hematoma of the left posterior fossa and the supratentorium and the clot was completely evacuated. The source of bleeding could not be identified. Opening of the dura revealed contusion in the occipital lobe. He died on the 17th postoperative day. The possible mechanism in the production of the posterior fossa hematoma in this case is discussed.

  5. Using a forehead reflectance pulse oximeter to detect changes in sympathetic tone.

    Science.gov (United States)

    Wendelken, Suzanne M; McGrath, Susan P; Akay, Metin; Blike, George T

    2004-01-01

    The extreme conditions of combat and multi-casualty rescue often make field triage difficult and put the medic or first responder at risk. In an effort to improve field triage, we have developed an automated remote triage system called ARTEMIS (automated remote triage and emergency management information system) for use in the battlefield or disaster zone. Common to field injuries is a sudden change in arterial pressure resulting from massive blood loss or shock. In effort to stabilize the arterial pressure, the sympathetic system is strongly activated and sympathetic tone is increased. This preliminary research seeks to empirically demonstrate that a forehead reflectance pulse oximeter is a viable sensor for detecting sudden changes in sympathetic tone. We performed the classic supine-standing experiment and collected the raw waveform, the photoplethysmogram (PPG), continuously using a forehead reflectance pulse oximeter. The resulting waveform was processed in Matlab using various spectral analysis techniques (FFT and AR). Our preliminary results show that a relative ratio analysis (low frequency power/high frequency power) for both the raw PPG signal and its derived pulse statistics (height, beat-to-beat interval) is a useful technique for detecting change in sympathetic tone resulting from positional change.

  6. Temperature behavior of the hole density of (Bi,Pb)-2212 single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ghafari, Aliakbar; Janowitz, Christoph; Dwelk, Helmut; Krapf, Alica; Manzke, Recardo [Institute of Physics, Humboldt University of Berlin, Newtonstr. 15, D-12489 Berlin (Germany); Ariffin, Ahmad Kamal [Dept. of Physics, Universiti Pendidikan Sultan Idris, 35900 Tanjong Malim (Malaysia)

    2012-07-01

    One of the most puzzling anomalies of high-T{sub c} cuprates is the strong temperature dependence of the Hall coefficient (R{sub H}) and the hole density (n{sub H}). Gor'kov and Teitel'baum (GT) showed by using experimental data of La{sub 2-x}Sr{sub x}CuO{sub 4} (LSCO) that the number of holes per Cu atom, n{sub H}, changes with temperature according to n{sub H}(T,x)=n{sub 0}(x)+n{sub 1}(x)exp(-{Delta}(x)/T). To clarify the temperature dependence of n{sub H} we have determined n{sub H} by X-ray absorption spectra (XAS) at the CuL{sub 3} edge for nearly optimum and slightly underdoped (Bi,Pb)-2212 single crystals. Our results point out that the GT formula cannot fit our data and therefore must be extended to the three terms.

  7. Crystal chemistry and temperature behavior of the natural hydrous borate colemanite, a mineral commodity of boron

    Science.gov (United States)

    Lotti, Paolo; Gatta, G. Diego; Demitri, Nicola; Guastella, Giorgio; Rizzato, Silvia; Ortenzi, Marco Aldo; Magrini, Fabrizio; Comboni, Davide; Guastoni, Alessandro; Fernandez-Diaz, Maria Teresa

    2018-05-01

    Colemanite, CaB3O4(OH)3ṡH2O, is the most common hydrous Ca-borate, as well as a major mineral commodity of boron. In this study, we report a thorough chemical analysis and the low-temperature behavior of a natural sample of colemanite by means of a multi-methodological approach. From the chemical point of view, the investigated sample resulted to be relatively pure, its composition being very close to the ideal one, with only a minor substitution of Sr2+ for Ca2+. At about 270.5 K, a displacive phase transition from the centrosymmetric P21/ a to the acentric P21 space group occurs. On the basis of in situ single-crystal synchrotron X-ray (down to 104 K) and neutron diffraction (at 20 K) data, the hydrogen-bonding configuration of both the polymorphs and the structural modifications at the atomic scale at varying temperatures are described. The asymmetric distribution of ionic charges along the [010] axis, allowed by the loss of the inversion center, is likely responsible for the reported ferroelectric behavior of colemanite below the phase transition temperature.

  8. Temperature dependences of the electrical conductivity and Hall coefficient of indium telluride single crystals

    International Nuclear Information System (INIS)

    Hussein, S.A.

    1989-01-01

    Conductivity type, carrier concentration and carrier mobility of InTe samples grown by Bridgman technique were determined by the Hall effect and electrical conductivity measurements. The study was performed in the temperature range 150-480 K. Two samples with different growth rate were used in the investigation. The samples under test were P-type conducting, in accordance with previous measurements of undoped material. The Hall coefficient was found to be isotropic yielding room temperature hole concentration in the range 10 15 -10 16 cm -3 . The hole mobilities of InTe samples were in the range 1.17 x 10 3 -2.06 x 10 3 cm 2 /V · sec at room temperature. The band-gap of InTe determined from Hall coefficient studies has been obtained equal to 0.34 eV. The scattering mechanism was checked, and the electrical properties were found to be sensitive to the crystal growth rate. (author)

  9. Piezoresistive polysilicon film obtained by low-temperature aluminum-induced crystallization

    International Nuclear Information System (INIS)

    Patil, Suraj Kumar; Celik-Butler, Zeynep; Butler, Donald P.

    2010-01-01

    A low-temperature deposition process employing aluminum-induced crystallization has been developed for fabrication of piezoresistive polycrystalline silicon (polysilicon) films on low cost and flexible polyimide substrates for force and pressure sensing applications. To test the piezoresistive properties of the polysilicon films, prototype pressure sensors were fabricated on surface-micromachined silicon nitride (Si 3 N 4 ) diaphragms, in a half-Wheatstone bridge configuration. Characterization of the pressure sensor was performed using atomic force microscope in contact mode with a specially modified probe-tip. Low pressure values ranging from 5 kPa to 45 kPa were achieved by this method. The resistance change was found to be - 0.1% to 0.5% and 0.07% to 0.3% for polysilicon films obtained at 500 o C and 400 o C, respectively, for the applied pressure range.

  10. Effects of low temperature neutron irradiation on the mechanical properties of iron single crystals

    International Nuclear Information System (INIS)

    Kitajima, K.; Abe, H.; Takamura, S.; Okuda, S.

    1975-01-01

    Measurements were made on tensile properties and their recovery characteristics of single crystals of pure iron and iron containing carbon of 4 to 60 ppm irradiated in reactor to the dose of 3 x 10 16 to approximately 3 x 10 17 nvt (greater than 0.1 MeV) at approximately 5 0 K. The yield stress showed large softening at less than or equal to 90 0 K saturating to a value nearly independent of orientations for greater than or equal to 1 x 10 17 nvt. The softening recovered and hardening set in at several temperature stages. The activation energies of the recovery and the activation parameters of plastic deformations at various annealing stages were determined. Carbon suppressed the softening and its recovery but much enhanced the hardening at the stage of 300 to approximately 400 0 K

  11. Photoluminescence at room temperature of liquid-phase crystallized silicon on glass

    Directory of Open Access Journals (Sweden)

    Michael Vetter

    2016-12-01

    Full Text Available The room temperature photoluminescence (PL spectrum due band-to-band recombination in an only 8 μm thick liquid-phase crystallized silicon on glass solar cell absorber is measured over 3 orders of magnitude with a thin 400 μm thick optical fiber directly coupled to the spectrometer. High PL signal is achieved by the possibility to capture the PL spectrum very near to the silicon surface. The spectra measured within microcrystals of the absorber present the same features as spectra of crystalline silicon wafers without showing defect luminescence indicating the high electronic material quality of the liquid-phase multi-crystalline layer after hydrogen plasma treatment.

  12. Characterization of polypropylene–polyethylene blends by temperature rising elution and crystallization analysis fractionation

    Science.gov (United States)

    del Hierro, Pilar

    2010-01-01

    The introduction of single-site catalysts in the polyolefins industry opens new routes to design resins with improved performance through multicatalyst-multireactor processes. Physical combination of various polyolefin types in a secondary extrusion process is also a common practice to achieve new products with improved properties. The new resins have complex structures, especially in terms of composition distribution, and their characterization is not always an easy task. Techniques like temperature rising elution fractionation (TREF) or crystallization analysis fractionation (CRYSTAF) are currently used to characterize the composition distribution of these resins. It has been shown that certain combinations of polyolefins may result in equivocal results if only TREF or CRYSTAF is used separately for their characterization. PMID:20730530

  13. Effect of irradiation temperature and initial crystal doping level on defect creation efficiency in silicon

    International Nuclear Information System (INIS)

    Korshunov, F.P.; Markevich, V.P.; Medvedeva, I.F.; Murin, L.I.

    1990-01-01

    The defect creation processes in n-type silicon irradiated by 60 Co gamma-rays or fast electrons (E = 4 MeV) have been investigated. Using electrical measurements the dependences of introduction efficiencies of the main radiation defects (A-, E-centres, carbon-related complexes) on the irradiation temperature (T irr = 77-470 K) and material doping level (N h = 2 x 10 12 - 2 x 10 15 cm -3 ) are obtained. It is shown that the efficiency of these defects formation is conditioned by the probability of the Frenkel pairs separation and depends strongly on the Fermi level position in crystals being irradiated. 9 refs.; 3 figs.; 1 tab

  14. Electronic properties of dislocations introduced mechanically at room temperature on a single crystal silicon surface

    International Nuclear Information System (INIS)

    Ogawa, Masatoshi; Kamiya, Shoji; Izumi, Hayato; Tokuda, Yutaka

    2012-01-01

    This paper focuses on the effects of temperature and environment on the electronic properties of dislocations in n-type single crystal silicon near the surface. Deep level transient spectroscopy (DLTS) analyses were carried out with Schottky electrodes and p + -n junctions. The trap level, originally found at E C -0.50 eV (as commonly reported), shifted to a shallower level at E C -0.23 eV after a heat treatment at 350 K in an inert environment. The same heat treatment in lab air, however, did not cause any shift. The trap level shifted by the heat treatment in an inert environment was found to revert back to the original level when the specimens were exposed to lab air again. Therefore, the intrinsic trap level is expected to occur at E C -0.23 eV and shift sensitively with gas adsorption in air.

  15. Thermodynamic properties of bcc crystals at high temperatures: The transition metals

    International Nuclear Information System (INIS)

    MacDonald, R.A.; Shukla, R.C.

    1985-01-01

    The second-neighbor central-force model of a bcc crystal, previously used in lowest-order anharmonic perturbation theory to calculate the thermodynamic properties of the alkali metals, is here applied to the transition metals V, Nb, Ta, Mo, and W. The limitations of the model are apparent in the thermal-expansion results, which fall away from the experimental trend above about 1800 K. The specific heat similarly fails to exhibit the sharp rise that is observed at higher temperatures. A static treatment of vacancies cannot account for the difference between theory and experiment. The electrons have been taken into account by using a model that specifically includes d-band effects in the electron ground-state energy. The results thus obtained for the bulk moduli are quite satisfactory. In the light of these results, we discuss the prerequisites for a better treatment of metals when the electrons play an important role in determining the thermodynamic properties

  16. Crystal structure of the low-temperature forms of cesium and rubidium orthophosphates

    International Nuclear Information System (INIS)

    Voronin, V.I.; Proskurina, N.V.; Goshchitskij, B.N.; Berger, I.F.; Sheptyakov, D.V.; Burmakin, E.I.; Stroev, S.S.; Shekhtman, G.Sh.

    2008-01-01

    Making use of the neutron diffraction data base Rietveld method one for the first time determined and made more clear the crystal structure of the low-temperature modifications of Cs 3 PO 4 cesium and Rb 3 PO 4 rubidium orthophosphates. Cs 3 PO 4 and Rb 3 PO 4 were found to be isostructural one as to K 3 PO 4 . The structure is a rhombic one (Pnma, Z=4 sp.gr.) with the following elementary cell parameters: a = 1.23177(6) nm, b=0.88948(4) nm, c=0.64197(3) nm and a = 1.17362(2) nm, b=0.81046(1) nm, c=0.615167(9) nm for Cs 3 PO 4 and Rb 3 PO 4 respectively [ru

  17. Preparation of single-crystal TiC (111) by radio frequency magnetron sputtering at low temperature

    International Nuclear Information System (INIS)

    Qi, Q.; Zhang, W.Z.; Shi, L.Q.; Zhang, W.Y.; Zhang, W.; Zhang, B.

    2012-01-01

    Single-crystal films of TiC (111) have been synthesized at room temperature on Al 2 O 3 (0001) substrates by radio frequency magnetron sputtering using a compound Ti–C target. The substrate temperature and bias were varied to explore the influence of deposition parameters on the crystal structure. Both Al 2 O 3 (0001) and Si (100) substrates were used for epitaxial growth of TiC films. A series of characterizations of TiC films were carried out, including Rutherford backscattering spectroscopy, X-ray diffraction, Raman and X-ray photoelectron spectroscopy. Single-crystal films of TiC (111) on the Al 2 O 3 (0001) were demonstrated. - Highlights: ► Single-crystal films of TiC (111) have been synthesized by RF magnetron sputtering. ► Both temperature and bias affect greatly the TiC crystal structure. ► Al 2 O 3 substrate is much better than Si substrate for TiC epitaxial growth. ► TiC (111) epitaxial film can be grown on Al 2 O 3 (0001) at room temperature.

  18. Complete Stokes polarimetry of magneto-optical Faraday effect in a terbium gallium garnet crystal at cryogenic temperatures.

    Science.gov (United States)

    Majeed, Hassaan; Shaheen, Amrozia; Anwar, Muhammad Sabieh

    2013-10-21

    We report the complete determination of the polarization changes caused in linearly polarized incident light due to propagation in a magneto-optically active terbium gallium garnet (TGG) single crystal, at temperatures ranging from 6.3 to 300 K. A 28-fold increase in the Verdet constant of the TGG crystal is seen as its temperature decreases to 6.3 K. In contrast with polarimetry of light emerging from a Faraday material at room temperature, polarimetry at cryogenic temperatures cannot be carried out using the conventional fixed polarizer-analyzer technique because the assumption that ellipticity is negligible becomes increasingly invalid as temperature is lowered. It is shown that complete determination of light polarization in such a case requires the determination of its Stokes parameters, otherwise inaccurate measurements will result with negative implications for practical devices.

  19. Effects of a facial nerve lesion on responses in forehead microvessels to conjunctival irritation and paced breathing.

    Science.gov (United States)

    Drummond, Peter D

    2012-08-16

    To investigate parasympathetic influences on the forehead microvasculature, blood flow was monitored bilaterally in seven participants with a unilateral facial nerve lesion during conjunctival irritation with Schirmer's strips and while breathing at 0.15 Hz. Blood flow and slow-wave frequency increased on the intact side of the forehead during Schirmer's test but did not change on the denervated side. However, a 0.15 Hz vascular wave strengthened during paced breathing, particularly on the denervated side. These findings indicate that parasympathetic activity in the facial nerve increases forehead blood flow during minor conjunctival irritation, but may interfere with the 0.15 Hz vascular wave. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. XPS analysis for cubic boron nitride crystal synthesized under high pressure and high temperature using Li3N as catalysis

    International Nuclear Information System (INIS)

    Guo, Xiaofei; Xu, Bin; Zhang, Wen; Cai, Zhichao; Wen, Zhenxing

    2014-01-01

    Highlights: • The cBN was synthesized by Li 3 N as catalyst under high pressure and high temperature (HPHT). • The film coated on the as-grown cBN crystals was studied by XPS. • The electronic structure variation in the film was investigated. • The growth mechanism of cubic boron nitride crystal was analyzed briefly. - Abstract: Cubic boron nitride (cBN) single crystals are synthesized with lithium nitride (Li3N) as catalyst under high pressure and high temperature. The variation of electronic structures from boron nitride of different layers in coating film on the cBN single crystal has been investigated by X-ray photoelectron spectroscopy. Combining the atomic concentration analysis, it was shown that from the film/cBN crystal interface to the inner, the sp 2 fractions are decreasing, and the sp 3 fractions are increasing in the film at the same time. Moreover, by transmission electron microscopy, a lot of cBN microparticles are found in the interface. For there is no Li 3 N in the film, it is possible that Li 3 N first reacts with hexagonal boron nitride to produce Li 3 BN 2 during cBN crystals synthesis under high pressure and high temperature (HPHT). Boron and nitrogen atoms, required for cBN crystals growth, could come from the direct conversion from hexagonal boron nitride with the catalysis of Li 3 BN 2 under high pressure and high temperature, but not directly from the decomposition of Li 3 BN 2

  1. Molecular-dynamic simulations of the thermophysical properties of hexanitrohexaazaisowurtzitane single crystal at high pressures and temperatures

    Science.gov (United States)

    Kozlova, S. A.; Gubin, S. A.; Maklashova, I. V.; Selezenev, A. A.

    2017-11-01

    Molecular dynamic simulations of isothermal compression parameters are performed for a hexanitrohexaazaisowurtzitane single crystal (C6H6O12N12) using a modified ReaxFF-log reactive force field. It is shown that the pressure-compression ratio curve for a single C6H6O12N12 crystal at constant temperature T = 300 K in pressure range P = 0.05-40 GPa is in satisfactory agreement with experimental compression isotherms obtained for a single C6H6O12N12 crystal. Hugoniot molecular-dynamic simulations of the shock-wave hydrostatic compression of a single C6H6O12N12 crystal are performed. Along with Hugoniot temperature-pressure curves, calculated shock-wave pressure-compression ratios for a single C6H6O12N12 crystal are obtained for a wide pressure range of P = 1-40 GPa. It is established that the percussive adiabat obtained for a single C6H6O12N12 crystal is in a good agreement with the experimental data. All calculations are performed using a LAMMPS molecular dynamics simulation software package that provides a ReaxFF-lg reactive force field to support the approach.

  2. Controllable Growth of Monolayer MoS2 and MoSe2 Crystals Using Three-temperature-zone Furnace

    Science.gov (United States)

    Zheng, Binjie; Chen, Yuanfu

    2017-12-01

    Monolayer molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) have attracted a great attention for their exceptional electronic and optoelectronic properties among the two dimensional family. However, controllable synthesis of monolayer crystals with high quality needs to be improved urgently. Here we demonstrate a chemical vapor deposition (CVD) growth of monolayer MoS2 and MoSe2 crystals using three-temperature-zone furnace. Systematical study of the effects of growth pressure, temperature and time on the thickness, morphology and grain size of crystals shows the good controllability. The photoluminescence (PL) characterizations indicate that the as-grown monolayer MoS2 and MoSe2 crystals possess excellent optical qualities with very small full-width-half-maximum (FWHM) of 96 me V and 57 me V, respectively. It is comparable to that of exfoliated monolayers and reveals their high crystal quality. It is promising that our strategy should be applicable for the growth of other transition metal dichalcogenides (TMDs) monolayer crystals.

  3. Ultrasound-induced crystallization around the glass transition temperature for Pd40Ni40P20 metallic glass

    International Nuclear Information System (INIS)

    Ichitsubo, Tetsu; Matsubara, Eiichiro; Kai, Satoshi; Hirao, Masahiko

    2004-01-01

    We have found that crystallization of a Pd 40 Ni 40 P 20 bulk metallic glass is accelerated in the vicinity of the glass transition temperature T g when it is subjected to sub/low-MHz frequency ultrasonic vibration. Resonance frequencies and internal frictions have been measured with the electromagnetic acoustic resonance (EMAR) technique. In the initial heating process of an as-cast glassy sample, the resonance frequencies jump up just above T g under ultrasonic excitation, which is attributed to nano-crystallization that is confirmed by the X-ray diffraction profile. However, such a notable change is not observed without ultrasonic vibration. The irregular Λ-shaped internal-friction peaks are also observed prior to the abrupt crystallization. This rapid crystallization is considered to be caused by a stochastic resonance, in which the jump frequency of atoms matches the frequency of the interatomic-potential change by the ultrasonic vibration

  4. Effect of deposition temperature on electron-beam evaporated polycrystalline silicon thin-film and crystallized by diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Yun, J., E-mail: j.yun@unsw.edu.au; Varalmov, S.; Huang, J.; Green, M. A. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052 (Australia); Kim, K. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052 (Australia); Suntech R and D Australia, Botany, New South Wales 2019 (Australia)

    2014-06-16

    The effects of the deposition temperature on the microstructure, crystallographic orientation, and electrical properties of a 10-μm thick evaporated Si thin-film deposited on glass and crystallized using a diode laser, are investigated. The crystallization of the Si thin-film is initiated at a deposition temperature between 450 and 550 °C, and the predominant (110) orientation in the normal direction is found. Pole figure maps confirm that all films have a fiber texture and that it becomes stronger with increasing deposition temperature. Diode laser crystallization is performed, resulting in the formation of lateral grains along the laser scan direction. The laser power required to form lateral grains is higher in case of films deposited below 450 °C for all scan speeds. Pole figure maps show 75% occupancies of the (110) orientation in the normal direction when the laser crystallized film is deposited above 550 °C. A higher density of grain boundaries is obtained when the laser crystallized film is deposited below 450 °C, which limits the solar cell performance by n = 2 recombination, and a performance degradation is expected due to severe shunting.

  5. A phenomenological creep model for nickel-base single crystal superalloys at intermediate temperatures

    Science.gov (United States)

    Gao, Siwen; Wollgramm, Philip; Eggeler, Gunther; Ma, Anxin; Schreuer, Jürgen; Hartmaier, Alexander

    2018-07-01

    For the purpose of good reproduction and prediction of creep deformation of nickel-base single crystal superalloys at intermediate temperatures, a phenomenological creep model is developed, which accounts for the typical γ/γ‧ microstructure and the individual thermally activated elementary deformation processes in different phases. The internal stresses from γ/γ‧ lattice mismatch and deformation heterogeneity are introduced through an efficient method. The strain hardening, the Orowan stress, the softening effect due to dislocation climb along γ/γ‧ interfaces and the formation of dislocation ribbons, and the Kear–Wilsdorf-lock effect as key factors in the main flow rules are formulated properly. By taking the cube slip in \\{100\\} slip systems and \\{111\\} twinning mechanisms into account, the creep behavior for [110] and [111] loading directions are well captured. Without specific interaction and evolution of dislocations, the simulations of this model achieve a good agreement with experimental creep results and reproduce temperature, stress and crystallographic orientation dependences. It can also be used as the constitutive relation at material points in finite element calculations with complex boundary conditions in various components of superalloys to predict creep behavior and local stress distributions.

  6. Very High Cycle Fatigue of Ni-Based Single-Crystal Superalloys at High Temperature

    Science.gov (United States)

    Cervellon, A.; Cormier, J.; Mauget, F.; Hervier, Z.; Nadot, Y.

    2018-05-01

    Very high cycle fatigue (VHCF) properties at high temperature of Ni-based single-crystal (SX) superalloys and of a directionally solidified (DS) superalloy have been investigated at 20 kHz and a temperature of 1000 °C. Under fully reversed conditions (R = - 1), no noticeable difference in VHCF lifetimes between all investigated alloys has been observed. Internal casting pores size is the main VHCF lifetime-controlling factor whatever the chemical composition of the alloys. Other types of microstructural defects (eutectics, carbides), if present, may act as stress concentration sites when the number of cycles exceed 109 cycles or when porosity is absent by applying a prior hot isostatic pressing treatment. For longer tests (> 30 hours), oxidation also controls the main crack initiation sites leading to a mode I crack initiation from oxidized layer. Under such conditions, alloy's resistance to oxidation has a prominent role in controlling the VHCF. When creep damage is present at high ratios (R ≥ 0.8), creep resistance of SX/DS alloys governs VHCF lifetime. Under such high mean stress conditions, SX alloys developed to retard the initiation and creep propagation of mode I micro-cracks from pores have better VHCF lifetimes.

  7. Effects of storage time and temperature on pH, specific gravity, and crystal formation in urine samples from dogs and cats.

    Science.gov (United States)

    Albasan, Hasan; Lulich, Jody P; Osborne, Carl A; Lekcharoensuk, Chalermpol; Ulrich, Lisa K; Carpenter, Kathleen A

    2003-01-15

    To determine effects of storage temperature and time on pH and specific gravity of and number and size of crystals in urine samples from dogs and cats. Randomized complete block design. 31 dogs and 8 cats. Aliquots of each urine sample were analyzed within 60 minutes of collection or after storage at room or refrigeration temperatures (20 vs 6 degrees C [68 vs 43 degrees F]) for 6 or 24 hours. Crystals formed in samples from 11 of 39 (28%) animals. Calcium oxalate (CaOx) crystals formed in vitro in samples from 1 cat and 8 dogs. Magnesium ammonium phosphate (MAP) crystals formed in vitro in samples from 2 dogs. Compared with aliquots stored at room temperature, refrigeration increased the number and size of crystals that formed in vitro; however, the increase in number and size of MAP crystals in stored urine samples was not significant. Increased storage time and decreased storage temperature were associated with a significant increase in number of CaOx crystals formed. Greater numbers of crystals formed in urine aliquots stored for 24 hours than in aliquots stored for 6 hours. Storage time and temperature did not have a significant effect on pH or specific gravity. Urine samples should be analyzed within 60 minutes of collection to minimize temperature- and time-dependent effects on in vitro crystal formation. Presence of crystals observed in stored samples should be validated by reevaluation of fresh urine.

  8. Influence of Crucible Support Rod on the Growth Rate and Temperature Gradient in a Bridgman Growth of Tin Crystal

    OpenAIRE

    IMASHIMIZU, Yuji; MIURA, Koji; KAMATA, Masaki; WATANABE, Jiro

    2003-01-01

    Bridgman growth of tincrystal was carried out in a graphite crucible that was fixed on a quartz support rod or a copper one. The growth rate and axial temperature distribution were examined by recording the temperature variation with time at each of four prescribed positions in the solid-liquidsystem during solidification, l) Actual growth rate of crystal increased with progress of solidification while the furnace elevated at a constant rate, but the tendency was different depending on the ty...

  9. [Effect of annealing temperature on the crystallization and spectroscopic response of a small-molecule semiconductor doped in polymer film].

    Science.gov (United States)

    Yin, Ming; Zhang, Xin-Ping; Liu, Hong-Mei

    2012-11-01

    The crystallization properties of the perylene (EPPTC) molecules doped in the solid film of the derivative of polyfluorene (F8BT) at different annealing temperatures, as well as the consequently induced spectroscopic response of the exciplex emission in the heterojunction structures, were studied in the present paper. Experimental results showed that the phase separation between the small and the polymer molecules in the blend film is enhanced with increasing the annealing temperature, which leads to the crystallization of the EPPTC molecules due to the strong pi-pi stacking. The size of the crystal phase increases with increasing the annealing temperature. However, this process weakens the mechanisms of the heterojunction configuration, thus, the total interfacial area between the small and the polymer molecules and the amount of exciplex are reduced significantly in the blend film. Meanwhile, the energy transfer from the polymer to the small molecules is also reduced. As a result, the emission from the exciplex becomes weaker with increasing the annealing temperature, whereas the stronger emission from the polymer molecules and from the crystal phase of the small molecules can be observed. These experimental results are very important for understanding and tailoring the organic heterojunction structures. Furthermore, this provides photophysics for improving the performance of photovoltaic or solar cell devices.

  10. Decoding Facial Esthetics to Recreate an Esthetic Hairline: A Method Which Includes Forehead Curvature.

    Science.gov (United States)

    Garg, Anil K; Garg, Seema

    2017-01-01

    The evidence suggests that our perception of physical beauty is based on how closely the features of one's face reflect phi (the golden ratio) in their proportions. By that extension, it must certainly be possible to use a mathematical parameter to design an anterior hairline in all faces. To establish a user-friendly method to design an anterior hairline in cases of male pattern alopecia. We need a flexible measuring tape and skin marker. A reference point A (glabella) is taken in between eyebrows. Mark point E, near the lateral canthus, 8 cm horizontal on either side from the central point A. A mid-frontal point (point B) is marked 8 cm from point A on the forehead in a mid-vertical plane. The frontotemporal points (C and C') are marked on the frontotemporal area, 8 cm in a horizontal plane from point B and 8 cm in a vertical plane from point E. The temporal peak points (D and D') are marked on the line joining the frontotemporal point C to the lateral canthus point E, slightly more than halfway toward lateral canthus, usually 5 cm from the frontotemporal point C. This line makes an anterior border of the temporal triangle. We have conducted a study with 431 cases of male pattern alopecia. The average distance of the mid-frontal point from glabella was 7.9 cm. The patient satisfaction reported was 94.7%. Our method gives a skeletal frame of the anterior hairline with minimal criteria, with no need of visual imagination and experience of the surgeon. It automatically takes care of the curvature of the forehead and is easy to use for a novice surgeon.

  11. Forehead Skin Blood Flow in Normal Neonates during Active and Quiet Sleep, Measured with a Diode Laser Doppler Instrument

    NARCIS (Netherlands)

    Suichies, H.E.; Aarnoudse, J.G.; Okken, A.; Jentink, H.W.; de Mul, F.F.M.; Greve, Jan

    1988-01-01

    Changes in forehead skin blood flow during active and quiet sleep were determined in 16 healthy neonates using a recently developed semi-conductor laser Doppler flow meter without light conducting fibres. Measurements were carried out at a postnatal age varying from 5 hours to 7 days. The two sleep

  12. A temperature dependent tunneling study of the spin density wave gap in EuFe2As2 single crystals.

    Science.gov (United States)

    Dutta, Anirban; Anupam; Hossain, Z; Gupta, Anjan K

    2013-09-18

    We report temperature dependent scanning tunneling microscopy and spectroscopy measurements on single crystals of EuFe2As2 in the 15-292 K temperature range. The in situ cleaved crystals show atomic terraces with homogeneous tunnel spectra that correlate well with the spin density wave (SDW) transition at a temperature, TSDW ≈ 186 K. Above TSDW the local tunnel spectra show a small depression in the density of states (DOS) near the Fermi energy (EF). The gap becomes more pronounced upon entering the SDW state with a gap value ∼90 meV at 15 K. However, the zero bias conductance remains finite down to 15 K indicating a finite DOS at the EF in the SDW phase. Furthermore, no noticeable change is observed in the DOS at the antiferromagnetic ordering transition of Eu(2+) moments at 19 K.

  13. Temperature dependence of Kerr coefficient and quadratic polarized optical coefficient of a paraelectric Mn:Fe:KTN crystal

    Directory of Open Access Journals (Sweden)

    Qieni Lu

    2015-08-01

    Full Text Available We measure temperature dependence on Kerr coefficient and quadratic polarized optical coefficient of a paraelectric Mn:Fe:KTN crystal simultaneously in this work, based on digital holographic interferometry (DHI. And the spatial distribution of the field-induced refractive index change can also be visualized and estimated by numerically retrieving sequential phase maps of Mn:Fe:KTN crystal from recording digital holograms in different states. The refractive indices decrease with increasing temperature and quadratic polarized optical coefficient is insensitive to temperature. The experimental results suggest that the DHI method presented here is highly applicable in both visualizing the temporal and spatial behavior of the internal electric field and accurately measuring electro-optic coefficient for electrooptical media.

  14. Effect of irradiation temperature on the efficiency of introduction of multivacancy defects into n-Si crystals

    International Nuclear Information System (INIS)

    Pagava, T. A.

    2006-01-01

    The n-Si single crystals are studied in order to gain insight into the effect of the temperature of irradiation T irr on the defect-production process. The samples under study were irradiated with 2-MeV electrons in the range T irr = 20-400 deg. C. Irradiated crystals were annealed isochronously in the temperature range from 80 to 600 deg. C. Measurements were carried out by the Hall method in the temperature range from 77 to 300 K. It is shown that the efficiency of introduction of radiation defects with a high thermal stability (T ann ≥ 350 deg. C) attains a maximum at T irr = 150 deg. C. The observed effect is accounted for by formation of multivacancy defects PV 2 on the basis of ionized E centers and nonequilibrium vacancies

  15. Liquidus temperature in the spinel primary phase field: A comparison between optical and crystal fraction methods

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Brian J.; Hrma, Pavel; Crum, Jarrod V.; Vienna, John D.; Schweiger, Michael J.; Rodriguez, Carmen P.; Peterson, Jacob A.

    2018-03-01

    Liquidus temperature (TL) was measured for simulated high-level waste borosilicate glasses covering a Hanford composition region, using an optical method and a crystal-fraction extrapolation method with X-ray diffraction data from isothermal heat treatments. The 38 glasses encompassed a one-component-at-a-time variation of a 16-component matrix. The TL values ranged from 1006°C to 1603°C. First-order polynomial models were fitted to data to obtain coefficients in terms of the effect of 1 mass% component addition on the TL: TL-increasing oxides Cr2O3 (264°C), “Others” (minor components, 163°C), oxides of noble metals (137°C), NiO (91°C), Al2O3 and Fe2O3 (~19–21°C); TL-decreasing oxides K2O (-26°C), Na2O (-41°C), and Li2O (-68°C); oxides of little effect MnO, P2O5, ZrO2, F, Bi2O3, SiO2, B2O3, and CaO (9 to -12°C). Also presented are temperatures (T1%) at which glasses contain 1 vol% of spinel as these values are considered relevant to the Hanford Tank Waste Treatment and Immobilization Plant. The measured and estimated values are compared and contrasted and the effect of TL and T1% on glass formulation is discussed.

  16. Influence of temperature rise distribution in second harmonic generation crystal on intensity distributions of output second harmonic wave

    International Nuclear Information System (INIS)

    Li Wei; Feng Guoying; Li Gang; Huang Yu; Zhang Qiuhui

    2009-01-01

    Second-harmonic generation (SHG) of high-intensity laser with an SHG crystal for type I angle phase matching has been studied by the use of a split-step algorithm based on the fast Fourier transform and a fourth-order Runge-Kutta (R-K) integrator. The transverse walk-off effect, diffraction, the second-order and the third-order nonlinear effects have been taken into consideration. Influences of a temperature rise distribution of the SHG crystal on the refractive indices of ordinary wave and extraordinary wave have been discussed. The rules of phase mismatching quantity, intensity distribution of output beam and frequency conversion efficiency varying with the temperature rise distribution of the SHG crystal have been analyzed quantitatively. The calculated results indicate that in a high power frequency conversion system, the temperature rise distribution of SHG crystal would result in the phase mismatching of fundamental and harmonic waves, leading to the variation of intensity distribution of the output beam and the decrease of the conversion efficiency. (authors)

  17. Phase relations study on the melting and crystallization regions of the Bi-2223 high temperature superconductor

    Directory of Open Access Journals (Sweden)

    Alexander Polasek

    2004-09-01

    Full Text Available The melting and solidification behavior of Bi2Sr2Ca2Cu3 O10 (Bi-2223 precursors has been studied. Nominal compositions corresponding to excess of liquid, Ca2CuO3 and CuO have been investigated. Each sample was made by packing a precursor powder into a silver crucible, in order to approximately simulate the situation found in 2223 silver-sheathed tapes. The samples were partially melted and then slow-cooled, being quenched from different temperatures and analyzed through X-ray diffraction (XRD and scanning electron microscopy (SEM/EDS. The precursors decomposed peritectically during melting, forming liquid and solid phases. Very long plates with compositions falling in the vicinity of the 2223 primary phase field formed upon slow-cooling. The 2223 phase may have been formed and the results suggest that long grains of this phase might be obtained by melting and crystallization if the exact peritectic region and the optimum processing conditions are found.

  18. Superlattice photonic crystal as broadband solar absorber for high temperature operation.

    Science.gov (United States)

    Rinnerbauer, Veronika; Shen, Yichen; Joannopoulos, John D; Soljačić, Marin; Schäffler, Friedrich; Celanovic, Ivan

    2014-12-15

    A high performance solar absorber using a 2D tantalum superlattice photonic crystal (PhC) is proposed and its design is optimized for high-temperature energy conversion. In contrast to the simple lattice PhC, which is limited by diffraction in the short wavelength range, the superlattice PhC achieves solar absorption over broadband spectral range due to the contribution from two superposed lattices with different cavity radii. The superlattice PhC geometry is tailored to achieve maximum thermal transfer efficiency for a low concentration system of 250 suns at 1500 K reaching 85.0% solar absorptivity. In the high concentration case of 1000 suns, the superlattice PhC absorber achieves a solar absorptivity of 96.2% and a thermal transfer efficiency of 82.9% at 1500 K, amounting to an improvement of 10% and 5%, respectively, versus the simple square lattice PhC absorber. In addition, the performance of the superlattice PhC absorber is studied in a solar thermophotovoltaic system which is optimized to minimize absorber re-emission by reducing the absorber-to-emitter area ratio and using a highly reflective silver aperture.

  19. Effect of Feed Melting, Temperature History and Minor Component Addition on Spinel Crystallization in High-Level Waste Glass

    International Nuclear Information System (INIS)

    Izak, Pavel; Hrma, Pavel R.; Arey, Bruce W.; Plaisted, Trevor J.

    2001-01-01

    This study was undertaken to help design mathematical models for high-level waste (HLW) glass melter that simulate spinel behavior in molten glass. Spinel, (Fe,Ni,Mn) (Fe,Cr)2O4, is the primary solid phase that precipitates from HLW glasses containing Fe and Ni in sufficient concentrations. Spinel crystallization affects the anticipated cost and risk of HLW vitrification. To study melting reactions, we used simulated HLW feed, prepared with co-precipitated Fe, Ni, Cr, and Mn hydroxides. Feed samples were heated up at a temperature-increase rate (4C/min) close to that which the feed experiences in the HLW glass melter. The decomposition, melting, and dissolution of feed components (such as nitrates, carbonates, and silica) and the formation of intermediate crystalline phases (spinel, sodalite (Na8(AlSiO4)6(NO2)2), and Zr-containing minerals) were characterized using evolved gas analysis, volume-expansion measurement, optical microscope, scanning electron microscope, thermogravimetric analysis, differential scanning calorimetry, and X-ray diffraction. Nitrates and quartz, the major feed components, converted to a glass-forming melt by 880C. A chromium-free spinel formed in the nitrate melt starting from 520C and Sodalite, a transient product of corundum dissolution, appeared above 600C and eventually dissolved in glass. To investigate the effects of temperature history and minor components (Ru,Ag, and Cu) on the dissolution and growth of spinel crystals, samples were heated up to temperatures above liquidus temperature (TL), then subjected to different temperature histories, and analyzed. The results show that spinel mass fraction, crystals composition, and crystal size depend on the chemical and physical makeup of the feed and temperature history

  20. Single-crystal-like GdNdO{sub x} thin films on silicon substrates by magnetron sputtering and high-temperature annealing for crystal seed layer application

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ziwei; Xiao, Lei; Liang, Renrong, E-mail: wang-j@tsinghua.edu.cn, E-mail: liangrr@tsinghua.edu.cn; Shen, Shanshan; Xu, Jun; Wang, Jing, E-mail: wang-j@tsinghua.edu.cn, E-mail: liangrr@tsinghua.edu.cn [Tsinghua National Laboratory for Information Science and Technology, Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

    2016-06-15

    Single-crystal-like rare earth oxide thin films on silicon (Si) substrates were fabricated by magnetron sputtering and high-temperature annealing processes. A 30-nm-thick high-quality GdNdO{sub x} (GNO) film was deposited using a high-temperature sputtering process at 500°C. A Gd{sub 2}O{sub 3} and Nd{sub 2}O{sub 3} mixture was used as the sputtering target, in which the proportions of Gd{sub 2}O{sub 3} and Nd{sub 2}O{sub 3} were controlled to make the GNO’s lattice parameter match that of the Si substrate. To further improve the quality of the GNO film, a post-deposition annealing process was performed at a temperature of 1000°C. The GNO films exhibited a strong preferred orientation on the Si substrate. In addition, an Al/GNO/Si capacitor was fabricated to evaluate the dielectric constant and leakage current of the GNO films. It was determined that the single-crystal-like GNO films on the Si substrates have potential for use as an insulator layer for semiconductor-on-insulator and semiconductor/insulator multilayer applications.

  1. Single-crystal-like GdNdOx thin films on silicon substrates by magnetron sputtering and high-temperature annealing for crystal seed layer application

    Directory of Open Access Journals (Sweden)

    Ziwei Wang

    2016-06-01

    Full Text Available Single-crystal-like rare earth oxide thin films on silicon (Si substrates were fabricated by magnetron sputtering and high-temperature annealing processes. A 30-nm-thick high-quality GdNdOx (GNO film was deposited using a high-temperature sputtering process at 500°C. A Gd2O3 and Nd2O3 mixture was used as the sputtering target, in which the proportions of Gd2O3 and Nd2O3 were controlled to make the GNO’s lattice parameter match that of the Si substrate. To further improve the quality of the GNO film, a post-deposition annealing process was performed at a temperature of 1000°C. The GNO films exhibited a strong preferred orientation on the Si substrate. In addition, an Al/GNO/Si capacitor was fabricated to evaluate the dielectric constant and leakage current of the GNO films. It was determined that the single-crystal-like GNO films on the Si substrates have potential for use as an insulator layer for semiconductor-on-insulator and semiconductor/insulator multilayer applications.

  2. The Silicon Environment in Silica Polymorphs, Aluminosilicate Crystals and Melts: An In Situ High Temperature XAS Study

    International Nuclear Information System (INIS)

    Cormier, L.; Neuville, D. R.; Roux, J.; Ligny, D. de; Henderson, G. S.; Flank, A.-M.; Lagarde, P.

    2007-01-01

    High temperature X-ray absorption spectroscopy at the Si K-edge has been used to obtain in situ information on SiO2 phase transitions upon heating. Important modifications are observed for the XANES spectra of the high temperature polymorphs, in relation to disordering of the SiO4 tetrahedra beyond the short-range correlations. This paper also presents the XANES spectra of anorthite (CaAl2Si2O8) from room temperature up to the melt (1900 K). This study shows the possibilities for determining the Si environment in crystals and glasses up to the liquid state using in situ XANES measurements

  3. Research of resonant losses of ultrasonic sound in the deformed single crystals in temperature range 77...300 K

    International Nuclear Information System (INIS)

    Petchenko, A.M.; Petchenko, G.A.

    2007-01-01

    The damped dislocation resonance in preliminary deformed up to 1 % single crystals KBr was investigated. The measurements of a frequency dependence of a dislocation damping decrement of ultrasonic sound were conducted in range of frequencies 7,5...217,5 MHz and temperature range 77...300 K. From the analysis of frequency spectrums the temperature course of a coefficient of phonon viscosity B was determined, which is agreed both with the theory and experimental literary data. The influencing temperature changes of length of a dislocation segment on parameters of a resonant maximum and dynamic drag of dislocations by phonons was revealed and analyzed

  4. Measurement of the electron and ion temperatures by the x-ray imaging crystal spectrometer on joint Texas experimental tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Yan, W.; Chen, Z. Y., E-mail: zychen@hust.edu.cn; Huang, D. W.; Tong, R. H.; Wang, S. Y.; Wei, Y. N.; Ma, T. K.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China); Jin, W. [Center of Interface Dynamics for Sustainability, China Academy of Engineering Physics, Chengdu, Sichuan 610200 (China); Lee, S. G. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Shi, Y. J. [Department of Nuclear Engineering, Seoul National University, Seoul 08826 (Korea, Republic of)

    2016-11-15

    An x-ray imaging crystal spectrometer has been developed on joint Texas experimental tokamak for the measurement of electron and ion temperatures from the K{sub α} spectra of helium-like argon and its satellite lines. A two-dimensional multi-wire proportional counter has been applied to detect the spectra. The electron and ion temperatures have been obtained from the Voigt fitting with the spectra of helium-like argon ions. The profiles of electron and ion temperatures show the dependence on electron density in ohmic plasmas.

  5. Ferroelectric InMnO{sub 3}: Growth of single crystals, structure and high-temperature phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Bekheet, Maged F., E-mail: maged.bekheet@ceramics.tu-berlin.de [Fachbereich Material‐ und Geowissenschaften, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Fachgebiet Keramische Werkstoffe / Chair of Advanced Ceramic Materials, Institut für Werkstoffwissenschaften und -technologien, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin (Germany); Svoboda, Ingrid; Liu, Na [Fachbereich Material‐ und Geowissenschaften, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Bayarjargal, Lkhamsuren [Institut für Geowissenschaften, Goethe-Universität, Altenhöferallee 1, d-60438 Frankfurt a.M. (Germany); Irran, Elisabeth [Institut für Chemie, Technische Universität Berlin, Straße des 17, Juni 135, 10623 Berlin (Germany); Dietz, Christian; Stark, Robert W.; Riedel, Ralf [Fachbereich Material‐ und Geowissenschaften, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Gurlo, Aleksander [Fachgebiet Keramische Werkstoffe / Chair of Advanced Ceramic Materials, Institut für Werkstoffwissenschaften und -technologien, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin (Germany)

    2016-09-15

    To understand the origin of the ferroelectricity in InMnO{sub 3}, single crystals with average size of 1 mm were grown in PbF{sub 2} flux at 950 °C. The results of single crystal X-ray diffraction, second harmonic generation and piezoresponse force microscopy studies of high-quality InMnO{sub 3} single crystals reveal that the room-temperature state in this material is ferroelectric with P6{sub 3}cm symmetry. The polar InMnO{sub 3} specimen undergoes a reversible phase transition from non-centrosymmetric P6{sub 3}cm structure to a centrosymmetric P6{sub 3}/mmc structure at 700 °C as confirmed by the in situ high-temperature Raman spectroscopic and synchrotron X-ray diffraction experiments. - Graphical abstract: Piezoresponse fore microscopy (PFM) studies of high quality InMnO{sub 3} single crystal revealed that the room-temperature state of this material is ferroelectric with a clear cloverleaf pattern corresponding to six antiphase ferroelectric domains with alternating polarization ±P{sub z}. Display Omitted - Highlights: • InMnO{sub 3} single crystals with average size of 1 mm were grown in PbF{sub 2} flux at 950 °C. • The room-temperature state of InMnO{sub 3} is ferroelectric with polar P6{sub 3}cm structure. • PolarInMnO{sub 3} reversibly transforms to a centrosymmetric P6{sub 3}/mmc structure above 700 °C.

  6. The influence of ion energy, target temperature, dose rate and crystal order on the shape of bombardment induced pyramids on copper crystals

    International Nuclear Information System (INIS)

    Tanovic, L.; Whitton, J.L.; Kofod, S.

    1978-01-01

    Following recent studies of energetic ion bombardment of copper, which established the conditions necessary for the production of cones/pyramids, investigations have been extended to include the effects of change in ion energy, target temperature and dose rate. In addition, the authors have attempted a detailed analysis of the influence of sample crystal orientation on the final form of pyramids and have investigated the stability of the pyramids as a function of the total dose. These experiments, as in earlier work, have been done using very pure copper, mass-analyzed ion beams and free of any metal contamination from, for example, defining apertures. (Auth.)

  7. Temperature sensitive molecularly imprinted microspheres for solid-phase dispersion extraction of malachite green, crystal violet and their leuko metabolites

    International Nuclear Information System (INIS)

    Tan, Lei; Chen, Kuncai; He, Rong; Peng, Rongfei; Huang, Cong

    2016-01-01

    This article demonstrates the feasibility of an alternative strategy for producing temperature sensitive molecularly imprinted microspheres (MIMs) for solid-phase dispersion extraction of malachite green, crystal violet and their leuko metabolites. Thermo-sensitive MIMs can change their structure following temperature stimulation. This allows capture and release of target molecules to be controlled by temperature. The fabrication technique provides surface molecular imprinting in acetonitrile using vinyl modified silica microspheres as solid supports, methacrylic acid and N-isopropyl acrylamide as the functional monomers, ethyleneglycol dimethacrylate as the cross-linker, and malachite green as the template. After elution of the template, the MIMs can be used for fairly group-selective solid phase dispersion extraction of malachite green, crystal violet, leucomalachite green, and leucocrystal violet from homogenized fish samples at a certain temperature. Following centrifugal separation of the microspheres, the analytes were eluted with a 95:5 mixture of acetonitrile and formic acid, and then quantified by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) with isotope internal calibration. The detection limits for malachite green, crystal violet and their metabolites typically are 30 ng·kg −1 . Positive samples were identified by UHPLC-MS/MS in the positive ionization mode with multiple reaction monitoring. The method was applied to the determination of the dyes and the respective leuko dyes in fish samples, and accuracy and precision were validated by comparative analysis of the samples by using aluminum neutral columns. (author)

  8. Upgrades of imaging x-ray crystal spectrometers for high-resolution and high-temperature plasma diagnostics on EAST

    Energy Technology Data Exchange (ETDEWEB)

    Lyu, B., E-mail: blu@ipp.ac.cn; Wang, F. D.; Fu, J.; Li, Y. Y. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Pan, X. Y.; Chen, J.; Wan, B. N. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China); Bitter, M.; Hill, K. W.; Delgado-Aparicio, L. F.; Pablant, N. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Lee, S. G. [National Fusion Research Institute, 52 Eoeun-Dong, Yusung-Gu, Daejeon 305-333 (Korea, Republic of); Shi, Y. J. [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China); WCI for Fusion Theory, National Fusion Research Institute, 52 Eoeun-Dong, Yusung-Gu, Daejeon 305-333 (Korea, Republic of); Ye, M. Y. [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-11-15

    Upgrade of the imaging X-ray crystal spectrometers continues in order to fulfill the high-performance diagnostics requirements on EAST. For the tangential spectrometer, a new large pixelated two-dimensional detector was deployed on tokamaks for time-resolved X-ray imaging. This vacuum-compatible detector has an area of 83.8 × 325.3 mm{sup 2}, a framing rate over 150 Hz, and water-cooling capability for long-pulse discharges. To effectively extend the temperature limit, a double-crystal assembly was designed to replace the previous single crystals for He-like argon line measurement. The tangential spectrometer employed two crystal slices attached to a common substrate and part of He- and H-like Ar spectra could be recorded on the same detector when crystals were chosen to have similar Bragg angles. This setup cannot only extend the measurable Te up to 10 keV in the core region, but also extend the spatial coverage since He-like argon ions will be present in the outer plasma region. Similarly, crystal slices for He-like iron and argon spectra were adopted on the poloidal spectrometer. Wavelength calibration for absolute rotation velocity measurement will be studied using cadmium characteristic L-shell X-ray lines excited by plasma radiation. A Cd foil is placed before the crystal and can be inserted and retracted for in situ wavelength calibration. The Geant4 code was used to estimate X-ray fluorescence yield and optimize the thickness of the foil.

  9. Effect of temperature gradient in the solution on spiral growth of YBa2Cu3O7-x bulk single crystals

    International Nuclear Information System (INIS)

    Kanamori, Y.; Shiohara, Y.

    1996-01-01

    Bulk single crystals of Y123 are required to clarify the superconductivity phenomena and develop electronic devices using unique superconductive properties. Only the Solute Rich Liquid endash Crystal Pulling (SRL-CP) method has succeeded in continuous growth of the Y123 single crystal. In this paper, we investigated the growth of Y123 single crystals under different temperature gradients in the solution in order to understand the growth mechanism of Y123. It was revealed that Y123 single crystals grow with a spiral growth mode, which is in good agreement with the BCF theory. copyright 1996 Materials Research Society

  10. Photocurrent response of B12As2 crystals to blue light, and its temperature- dependent electrical characterizations

    Directory of Open Access Journals (Sweden)

    R. Gul

    2016-02-01

    Full Text Available With the global shortage of 3He gas, researchers worldwide are looking for alternative materials for detecting neutrons. Among the candidate materials, semiconductors are attractive because of their light weight and ease in handling. Currently, we are looking into the suitability of boron arsenide (B12As2 for this specific application. As the first step in evaluating the material qualitatively, the photo-response of B12As2 bulk crystals to light with different wavelengths was examined. The crystals showed photocurrent response to a band of 407- and 470- nm blue light. The maximum measured photoresponsivity and the photocurrent density at 0.7 V for 470 nm blue light at room temperature were 0.25 A ⋅ W−1 and 2.47 mA ⋅ cm−2, respectively. In addition to photo current measurements, the electrical properties as a function of temperature (range: 50-320 K were measured. Reliable data were obtained for the low-temperature I-V characteristics, the temperature dependence of dark current and its density, and the resistivity variations with temperature in B12As2 bulk crystals. The experiments showed an exponential dependence on temperature for the dark current, current density, and resistivity; these three electrical parameters, respectively, had a variation of a few nA to μA, 1-100 μA ⋅ cm−2 and 7.6x105-7.7x103 Ω ⋅ cm, for temperature increasing from 50 K to 320 K. The results from this study reported the first photoresponse and demonstrated that B12As2 is a potential candidate for thermal-neutron detectors.

  11. Temperature effects on the band gaps of Lamb waves in a one-dimensional phononic-crystal plate (L).

    Science.gov (United States)

    Cheng, Y; Liu, X J; Wu, D J

    2011-03-01

    This study investigates the temperature-tuned band gaps of Lamb waves in a one-dimensional phononic-crystal plate, which is formed by alternating strips of ferroelectric ceramic Ba(0.7)Sr(0.3)TiO(3) and epoxy. The sensitive and continuous temperature-tunability of Lamb wave band gaps is demonstrated using the analyses of the band structures and the transmission spectra. The width and position of Lamb wave band gaps shift prominently with variation of temperature in the range of 26 °C-50 °C. For example, the width of the second band gap increases from 0.066 to 0.111 MHz as the temperature is increased from 26 °C to 50 °C. The strong shift promises that the structure could be suitable for temperature-tuned multi-frequency Lamb wave filters. © 2011 Acoustical Society of America

  12. Alteration of Skin Mechanical Properties in Patients Undergoing Botulinum Toxin Type A Injections of Forehead Rhytides.

    Science.gov (United States)

    Min, Peiru; Zhang, Zheng; Grassetti, Luca; Perdanasari, Aurelia Trisliana; Torresetti, Matteo; Pu, Zheming; Zhang, Yan; Han, Sheng; Marsili, Riccardo; Zhang, Yi Xin; di Benedetto, Giovanni; Lazzeri, Davide

    2016-06-01

    Although application of botulinum toxin type A (BTX-A) for the treatment of forehead rhytides has become very popular, the effects of its intramuscular injections on the skin mechanical properties remain unclear. We prospectively investigated the alterations in the mechanical properties of the skin of patients who received intramuscular injections of botulinum toxin A (BTX-A) for forehead rhytides and compared two injection doses. Of the 42 enrolled patients, one randomly assigned half received intramuscular injections of two units (group I), and the other half received four units (group II) of BTX-A in each injection point. The baseline and post-treatment skin mechanical parameters, including gross elasticity (R2), net elasticity (R5), viscoelastic ratio (R6) and biological elasticity (R7), were measured using the Cutometer(®) and compared. Treatment with BTX-A resulted in significant overall alterations in the mechanical properties of skin at the injection sites of both treatment groups during the 16-week period, and no significant differences were observed between groups. Significant decreases in biological elasticity, net elasticity and viscoelasticity properties were observed at 2 weeks follow-up and began to recover at that time. All of the skin mechanical properties recovered to baseline levels by 16 weeks of follow-up in both dosage groups, which indicates that the higher dosage (4 units) did not delay relapse compared to the two-unit dosage. We concluded that intramuscular injections of BTX-A significantly regulated the gross elasticity, net elasticity, functional elasticity and viscoelastic elasticity at the injection point over a radius of 1.5 cm at 2, 4 and 8 weeks follow-up. The alteration in the skin measurements had completely diminished by the 16-week follow-up. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or

  13. Prototyping and performance study of a single crystal diamond detector for operation at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Amit; Kumar, Arvind; Topkar, Anita, E-mail: anita@barc.gov.in; Das, D.

    2017-06-21

    Prototype single crystal diamond detectors with different types of metallization and post metallization treatment were fabricated for the applications requiring fast neutron measurements in the Indian Test Blanket Module (TBM) at the International Thermonuclear Experimental Reactor (ITER) Experiment. The detectors were characterized by leakage current measurements to ascertain that the leakage currents are low and breakdown voltages are higher than the voltage required for full charge collection. The detector response to charged particles was evaluated using a {sup 238+239} Pu dual energy alpha source. The detectors showed an energy resolution of about 2% at 5.5 MeV. In order to study their suitability for the operation at higher temperatures, leakage current variation and alpha response were studied up to 300 °C. At 300 °C, peaks corresponding to 5.156 MeV and 5.499 MeV alphas could be separated and there was no significant degradation of energy resolution. Finally, the detector response to fast neutrons was evaluated using a Deuterium-Tritium (D-T) neutron generator. The observed spectrum showed peaks corresponding to various channels of n-C interactions with a clear isolated peak corresponding to ~8.5 MeV alphas. The detectors also showed high sensitivity of 3.4×10{sup −2} cps/n/(cm{sup 2} s)–4.5×10{sup −2} cps/n/(cm{sup 2} s) and excellent linearity of response in terms of count rate at different neutron flux in the observed range of 3.2×10{sup 5} n/(cm{sup 2} s) to 2.0×10{sup 6} n/(cm{sup 2} s).

  14. Prototyping and performance study of a single crystal diamond detector for operation at high temperatures

    Science.gov (United States)

    Kumar, Amit; Kumar, Arvind; Topkar, Anita; Das, D.

    2017-06-01

    Prototype single crystal diamond detectors with different types of metallization and post metallization treatment were fabricated for the applications requiring fast neutron measurements in the Indian Test Blanket Module (TBM) at the International Thermonuclear Experimental Reactor (ITER) Experiment. The detectors were characterized by leakage current measurements to ascertain that the leakage currents are low and breakdown voltages are higher than the voltage required for full charge collection. The detector response to charged particles was evaluated using a 238+239 Pu dual energy alpha source. The detectors showed an energy resolution of about 2% at 5.5 MeV. In order to study their suitability for the operation at higher temperatures, leakage current variation and alpha response were studied up to 300 °C. At 300 °C, peaks corresponding to 5.156 MeV and 5.499 MeV alphas could be separated and there was no significant degradation of energy resolution. Finally, the detector response to fast neutrons was evaluated using a Deuterium-Tritium (D-T) neutron generator. The observed spectrum showed peaks corresponding to various channels of n-C interactions with a clear isolated peak corresponding to 8.5 MeV alphas. The detectors also showed high sensitivity of 3.4×10-2 cps/n/(cm2 s)-4.5×10-2 cps/n/(cm2 s) and excellent linearity of response in terms of count rate at different neutron flux in the observed range of 3.2×105 n/(cm2 s) to 2.0×106 n/(cm2 s).

  15. Accurate dew-point measurement over a wide temperature range using a quartz crystal microbalance dew-point sensor

    International Nuclear Information System (INIS)

    Kwon, Su-Yong; Kim, Jong-Chul; Choi, Buyng-Il

    2008-01-01

    Quartz crystal microbalance (QCM) dew-point sensors are based on frequency measurement, and so have fast response time, high sensitivity and high accuracy. Recently, we have reported that they have the very convenient attribute of being able to distinguish between supercooled dew and frost from a single scan through the resonant frequency of the quartz resonator as a function of the temperature. In addition to these advantages, by using three different types of heat sinks, we have developed a QCM dew/frost-point sensor with a very wide working temperature range (−90 °C to 15 °C). The temperature of the quartz surface can be obtained effectively by measuring the temperature of the quartz crystal holder and using temperature compensation curves (which showed a high level of repeatability and reproducibility). The measured dew/frost points showed very good agreement with reference values and were within ±0.1 °C over the whole temperature range

  16. Equation of state calculations for two-dimensional dust coulomb crystal at near zero temperature by molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Djouder, M., E-mail: djouder-madjid@ummto.dz; Kermoun, F.; Mitiche, M. D.; Lamrous, O. [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri Tizi-Ouzou, BP 17 RP, 15000 Tizi-Ouzou (Algeria)

    2016-01-15

    Dust particles observed in universe as well as in laboratory and technological plasma devices are still under investigation. At low temperature, these particles are strongly negatively charged and are able to form a 2D or 3D coulomb crystal. In this work, our aim was to check the ideal gas law validity for a 2D single-layer dust crystal recently reported in the literature. For this purpose, we have simulated, using the molecular dynamics method, its thermodynamic properties for different values of dust particles number and confinement parameters. The obtained results have allowed us to invalidate the ideal gas behaviour and to propose an effective equation of state which assumes a near zero dust temperature. Furthermore, the value of the calculated sound velocity was found to be in a good agreement with experimental data published elsewhere.

  17. Temperature dependence of Raman scattering spectra of Basub(0.50)Srsub(0.50)Nbsub(2)Osub(6) crystal

    International Nuclear Information System (INIS)

    Gorelik, V.S.; Rustamov, Kh.Sh.; Kuz'minov, Yu.S.; Sushchinskij, M.M.

    1977-01-01

    The change of the Raman spectra in the crystal Basub(x)Srsub(1-x)Nbsub(2)Osub(6) (x=0.50) in the temperature range of 80-500 K has been studied. A conventional technique with the application of an argon laser (π=4880 A) and a diffraction spectrometer was used. It has been established that in the observed spectrum a number of low frequency lines are present caused by vibrations of the crystalline lattice. It is shown that the growth of dielectric permittivity near the ferroelectric transition correlates with the observed growth of the spectral intensity in the low frequency spectrum range at the approach to the Gurie temperature. It was found that for the considered crystal, both a ''single-mode'' and a ''two-mode'' behaviour of the phonon spectrum take place

  18. Temperature dependence of Raman spectra of Basub(0.25)Srsub(0.75)Nbsub(2)Osub(6) crystal

    International Nuclear Information System (INIS)

    Rustamov, Kh.Sh.; Gorelik, V.S.; Kuz'minov, Yu.S.; Peregudov, G.V.; Sushchinskij, M.M.

    1976-01-01

    The nature of the changes is studied in the Raman spectra in a crystal of Basub(x)Srsub(1-x)Nasub(2)Osub(6) (x=0.25) with the temperature range of 80 to 373 K. Normal procedure was applied with the use of an argon laser (Λ=4880 A) and a DFS-12 spectrometer. It has been established that at low temperatures the spectrum becomes more clear-cut; in the low-frequency range some sharp lines appear in the immediate vicinity of the exciting line. On heating of the crystal one observes a redistribution of the intensity in the Raman spectrum and a general displacement of the low-frequency Raman spectrum and a general displacement of the low-frequency Raman spectrum toward the exciting line. The nature of the frequency shifts some Raman maxima was investigated, and certain anomalies were observed in the vicinity of the phase transition point

  19. Synthesis and temperature dependent Raman studies of large crystalline faces topological GeBi4Te7 single crystal

    Science.gov (United States)

    Mal, Priyanath; Bera, G.; Turpu, G. R.; Srivastava, Sunil K.; Das, Pradip

    2018-05-01

    We present a study of structural and vibrational properties of topological insulator GeBi4Te7. Modified Bridgeman technique is employed to synthesize the single crystal with relatively large crystalline faces. Sharp (0 0 l) reflection confirms the high crystallinity of the single crystal. We have performed temperature dependent Raman measurement for both parallel and perpendicular to crystallographic c axis geometry. In parallel configuration we have observed seven Raman modes whereas in perpendicular geometry only four of these are identified. Appearance and disappearance of Raman modes having different intensities for parallel and perpendicular to c measurement attribute to the mode polarization. Progressive blue shift is observed with lowering temperature, reflects the increase in internal stress.

  20. Equation of state calculations for two-dimensional dust coulomb crystal at near zero temperature by molecular dynamics simulations

    International Nuclear Information System (INIS)

    Djouder, M.; Kermoun, F.; Mitiche, M. D.; Lamrous, O.

    2016-01-01

    Dust particles observed in universe as well as in laboratory and technological plasma devices are still under investigation. At low temperature, these particles are strongly negatively charged and are able to form a 2D or 3D coulomb crystal. In this work, our aim was to check the ideal gas law validity for a 2D single-layer dust crystal recently reported in the literature. For this purpose, we have simulated, using the molecular dynamics method, its thermodynamic properties for different values of dust particles number and confinement parameters. The obtained results have allowed us to invalidate the ideal gas behaviour and to propose an effective equation of state which assumes a near zero dust temperature. Furthermore, the value of the calculated sound velocity was found to be in a good agreement with experimental data published elsewhere

  1. ESR and ENDOR of free radicals in γ-irradiated single crystals of trimethoprim at room temperature

    International Nuclear Information System (INIS)

    Krzyminiewski, R.; Kawacka, U.; Pietrzak, J.; Erickson, R.; Lund, A.

    1995-01-01

    Singe crystals of trimethoprim were examined after γ-irradiation at room temperature by ESR and ENDOR spectroscopy. A radicals is formed by abstraction of a hydrogen atom from the CH 2 group of the bridge. The unpaired electron is delocalized mainly onto the trimethoxybenzyl ring. It interacts with one proton of the bridge and with two protons in the trimethoxybenzyl ring. (au) (14 refs.)

  2. Low-temperature positron lifetime and Doppler-broadening measurements for single-crystal nickel oxide containing cation vacancies

    International Nuclear Information System (INIS)

    Waber, J.T.; Snead, C.L. Jr.; Lynn, K.G.

    1985-01-01

    Lifetime and Doppler-broadening measurements for positron annihilation in substoichiometric nickelous oxide have been made concomitantly from liquid-helium to room temperature. The concentration of cation vacancies is readily controlled by altering the ambient oxygen pressure while annealing the crystals at 1673 0 K. It was found that neither of the three lifetimes observed or their relative intensities varied significantly with the oxygen pressure, and the bulk rate only increased slightly when the specimen was cooled from room to liquid-helium temperatures. These results are interpreted as indicating that some of the positrons are trapped by the existing cation vacancies and a smaller fraction by vacancy clusters

  3. Temperature-Induced Lattice Relaxation of Perovskite Crystal Enhances Optoelectronic Properties and Solar Cell Performance

    KAUST Repository

    Banavoth, Murali; Yengel, Emre; Peng, Wei; Chen, Zhijie; Alias, Mohd Sharizal; Alarousu, Erkki; Ooi, Boon S.; Burlakov, Victor; Goriely, Alain; Eddaoudi, Mohamed; Bakr, Osman; Mohammed, Omar F.

    2016-01-01

    Hybrid organic-inorganic perovskite crystals have recently become one of the most important classes of photoactive materials in the solar cell and optoelectronic communities. Albeit improvements have focused on state-of-the-art technology including

  4. Native defect changes in CdS single crystal platelets induced by vacuum heat treatments at temperatures up to 600/sup 0/C

    Energy Technology Data Exchange (ETDEWEB)

    Christmann, M H; Dierssen, G H; Salmon, O N; Taylor, A L; Thom, W H

    1975-12-01

    Physical properties of selected CdS single crystal platelets as-grown and after vacuum heat treatments at temperatures up to 600/sup 0/C were studied using uv excited edge emission, mass spectrometry, electrical resistivity, and electron paramagnetic resonance (EPR). It was found that sulfur leaves the crystal at temperatures as low as 100/sup 0/C creating a depletion layer. The native defect changes were monitored by edge emission studies at 4.2/sup 0/K in combination with etch treatments. The defect structure throughout the crystal is not only dependent upon the temperature and atmosphere of the treatments, but is also strongly dependent upon the cooling rate. (auth)

  5. Thermal expansion and cooling rate dependence of transition temperature in ZrTiO4 single crystal

    International Nuclear Information System (INIS)

    Park, Y.

    1998-01-01

    Thermal expansion in ZrTiO 4 single crystal was investigated in the temperature range covering the normal, incommensurate, and commensurate phases. Remarkable change was found at the normal-incommensurate phase transition (T I ) in all thermal expansion coefficients a, b, and c. The spontaneous strains χ as and χ bs along the a and b axes show linear temperature dependence, while the spontaneous strain χ cs along the c axis shows a nonlinear temperature dependence. Small discontinuity along the c direction was observed at the incommensurate-commensurate transition temperature, T c = 845 C. dT I /dP and dT c /dP depend on the cooling rate

  6. Using renewable ethanol and isopropanol for lipid transesterification in wet microalgae cells to produce biodiesel with low crystallization temperature

    International Nuclear Information System (INIS)

    Huang, Rui; Cheng, Jun; Qiu, Yi; Li, Tao; Zhou, Junhu; Cen, Kefa

    2015-01-01

    Highlights: • Ethanol and isopropanol were used for transesterification in wet microalgae cell. • Decreased droplet size and polarity of lipid were observed after transesterification. • Ethanol and isopropanol dosage needed for 95% FAAE yield were 75% of methanol dosage. • Crystallization temperature of crude biodiesel decreased from 2.08 °C to −3.15 °C. - Abstract: Renewable ethanol and isopropanol were employed for lipid transesterification in wet microalgae cells to produce biodiesel with low crystallization temperature and reduce the alcohol volume needed for biodiesel production. Decreased droplet size and lipid polarity were observed after transesterification with alcohol in microalgae cells. Such decrease was beneficial in extracting lipid from microalgae with apolar hexane. The effects of reaction temperature, reaction time, and alcohol volume on microwave-assisted transesterification with ethanol and isopropanol were investigated, and results were compared with those with methanol. Microwave-assisted transesterification with ethanol and isopropanol, which were more miscible with lipid in cells, resulted in higher fatty acid alkyl ester (FAAE) yields than that with methanol when the reaction temperature was lower than 90 °C. The ethanol and isopropanol volumes in the transesterification with 95% FAAE yield were only 75% of the methanol volume. The crystallization temperatures (0.19 °C and −3.15 °C) of biodiesels produced from wet microalgae through lipid transesterification in cells with ethanol and isopropanol were lower than that with methanol (2.08 °C), which was favorable for biodiesel flow in cold districts and winter.

  7. Biomimetic and Aggregation-Driven Crystallization Route for Room-Temperature Material Synthesis: Growth of β-Ga2O3 Nanoparticles Using Peptide Assemblies as Nanoreactors

    Science.gov (United States)

    Lee, Sang-Yup; Gao, Xueyun; Matsui, Hiroshi

    2008-01-01

    The room temperature synthesis of β-Ga2O3 nanocrystal was examined by coupling two biomimetic crystallization techniques, the enzymatic peptide nano-assembly templating and the aggregation-driven crystallization. The catalytic template of peptide assembly nucleated and mineralized primary β-Ga2O3 crystals, and then fused them to grow single-crystalline and monodisperse nanoparticles in the cavity of the peptide assembly at room temperature. In this work, the peptide assembly was exploited as a nano-reactor with an enzymatic functionality catalyzing the hydrolysis of gallium precursors. In addition, the characteristic ring-structure of peptide assembly is expected to provide an efficient dehydration pathway and the crystallization control over the surface tension, which are advantageous for the β-Ga2O3 crystal growth. This multifunctional peptide assembly could be applied for syntheses of a variety of nanomaterials that are kinetically difficult to grow at room temperature. PMID:17302413

  8. Reconstruction of the columella and the tip of the nose with an island-shaped forehead flap

    Directory of Open Access Journals (Sweden)

    Vulović Dejan

    2011-01-01

    Full Text Available Background. Posttraumatic and postoperative defects of columella and the tip of the nose are difficult to reconstruct. There are several operative methods described in the literature, and many of them are step-by-step procedures with long duration. The aim of this study was to present one-step procedure for reconstruction of the columella and the tip of the nose with island-shaped arterial forehead flap. Case report. A 45-year old man was submitted to surgical excision of basocellular skin cancer. After the excision, a defect of the columella and tip of the nose the remained, 3 × 2.5 cm in dimensions, with exposed alar cartilages. During the same operation, the defect was covered with an island-shaped arterial forehead flap. Postoperative one-year course was uneventful, without signs of tumor recurrence after one year, and further surgical corrections were unnecessary. Conclusion. Considering the results of our operative technique, we believe that middle island-shaped forehead flap is suitable for reconstruction of the columella and the tip of the nose, due to the following reasons: safe vascularization of flap, similarity of the transferred tissue with the excised one, the procedure is completed in one step, simple surgical technique and uncomplicated healing of a flap-harvesting site.

  9. In-situ temperature field measurements and direct observation of crystal/melt at vertical Bridgman growth of lead chloride under stationary and dynamic arrangement

    Czech Academy of Sciences Publication Activity Database

    Král, Robert; Nitsch, Karel

    2015-01-01

    Roč. 427, Oct (2015), 7-15 ISSN 0022-0248 R&D Projects: GA MŠk(CZ) LH14266 Institutional support: RVO:68378271 Keywords : single crystal growth * temperature field measurements * crystal/melt interface * lead chloride * vertical Bridgman method Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.462, year: 2015

  10. BiI{sub 3} single crystal for room-temperature gamma ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Saito, T., E-mail: saito.tatsuya125@canon.co.jp [Frontier Research Center, Canon Inc., 3-30-2, Shimomaruko, Ohta-ku, Tokyo 146-8501 (Japan); Iwasaki, T. [Frontier Research Center, Canon Inc., 3-30-2, Shimomaruko, Ohta-ku, Tokyo 146-8501 (Japan); Kurosawa, S.; Yoshikawa, A. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Den, T. [Frontier Research Center, Canon Inc., 3-30-2, Shimomaruko, Ohta-ku, Tokyo 146-8501 (Japan)

    2016-01-11

    BiI{sub 3} single crystals were grown by the physical vapor transport method. The repeated sublimation of the starting material reduced impurities in the BiI{sub 3} single crystal to sub-ppm levels. The detector was fabricated by depositing Au electrodes on both surfaces of the 100-μm-thick BiI{sub 3} single crystal platelet. The resistivity of the BiI{sub 3} single crystal was increased by post-annealing in an iodine atmosphere (ρ=1.6×10{sup 11} Ω cm). Pulse height spectroscopy measurements showed clear peaks in the energy spectrum of alpha particles or gamma rays. It was estimated that the mobility-lifetime product was μ{sub e}τ{sub e}=3.4–8.5×10{sup −6} cm{sup 2}/V and the electron–hole pair creation energy was 5.8 eV. Our results show that BiI{sub 3} single crystals are promising candidates for detectors used in radiographic imaging or gamma ray spectroscopy.

  11. Temperature and Pressure Dependences of the Elastic Properties of Tantalum Single Crystals Under Tensile Loading: A Molecular Dynamics Study

    Science.gov (United States)

    Li, Wei-bing; Li, Kang; Fan, Kan-qi; Zhang, Da-xing; Wang, Wei-dong

    2018-04-01

    Atomistic simulations are capable of providing insights into physical mechanisms responsible for mechanical properties of the transition metal of Tantalum (Ta). By using molecular dynamics (MD) method, temperature and pressure dependences of the elastic properties of Ta single crystals are investigated through tensile loading. First of all, a comparative study between two types of embedded-atom method (EAM) potentials is made in term of the elastic properties of Ta single crystals. The results show that Ravelo-EAM (Physical Review B, 2013, 88: 134101) potential behaves well at different hydrostatic pressures. Then, the MD simulation results based on the Ravelo-EAM potential show that Ta will experience a body-centered-cubic (BCC) to face-centered-cubic (FCC) phase transition before fracture under tensile loading at 1 K temperature, and model size and strain rate have no obvious effects on tensile behaviors of Ta. Next, from the simulation results at the system temperature from 1 to 1500 K, it can be derived that the elastic modulus of E 100 linearly decrease with the increasing temperature, while the yielding stress decrease with conforming a quadratic polynomial formula. Finally, the pressure dependence of the elastic properties is performed from 0 to 140 GPa and the observations show that the elastic modulus increases with the increasing pressure overall.

  12. Effects of Phonon Coupling and Free Carriers on Band-Edge Emission at Room Temperature in n-type ZnO Crystals

    National Research Council Canada - National Science Library

    Giles, N. C; Xu, Chunchuan; Callahan, M. J; Wang, Buguo; Neal, J. S; Boatner, L. A

    2008-01-01

    Room-temperature photoluminescence has been studied in II-type bulk ZnO crystals representing three different growth methods and having free-carrier concentrations (n) ranging from 10(exp 13) to 10(exp 18) /cu cm...

  13. Single crystal growth and low-temperature properties of Er{sub 3}Al{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Suttner, Christian; Benka, Georg; Bauer, Andreas; Pfleiderer, Christian [Physik Department, Technische Universitaet Muenchen, D-85748 Garching (Germany)

    2016-07-01

    In recent years, topologically non-trivial spin whirls in condensed matter systems attracted great scientific interest. Lattices of these objects, so-called magnetic skyrmion lattices, were mainly observed in Dzyaloshinskii-Moriya driven chiral magnets with the non-centrosymmetric cubic space group P2{sub 1}3. Similar spin textures, however, may in principle also arise in a large number of further compounds. We report single-crystal growth of Er{sub 3}Al{sub 2} crystallizing in the tetragonal space group P4{sub 2}/mnm by means of optical float zoning under UHV-compatible conditions. We determined the magnetic phase diagram for fields applied along different crystallographic directions using magnetization, ac susceptibility, and specific heat measurements. Several phase pockets are observed below the Neel temperature T{sub N} = 27 K, consistent with earlier reports.

  14. Contribution of a solute atoms in the relaxation phenomenon at high temperature in Cu-Al single crystal alloys

    Science.gov (United States)

    Belamri, C.; Belhas, S.; Rivière, A.

    2009-11-01

    Two Cu-Al single crystals with 7 and 14 at. % Al respectively have been studied using isothermal mechanical spectroscopy (IMS) technique. After a 1% cold work by torsion, the samples have been progressively heated to 1140 K and then cooled until room temperature. IMS experiments allow to compare the isothermal internal friction spectra obtained during the heating (in this case, the annealing temperature is equal to the temperature of measurement) with the measurements performed at various temperature during the cooling after the annealing at 1140 K. Three relaxation peaks were observed. The first one at about 0.4 TM (TM: melting point) is a Zener relaxation peak (PZ) due to the reorientation under constraint of pairs of aluminium atoms. The high temperature annealing does not influence PZ. At about 0.6TM, a peak (P1) related to a dislocation mechanism is evidenced. The relaxation strength of P1 peak decreases with the temperature and a new relaxation peak (P2) is progressively developed. The IMS spectra obtained during the cooling evidenced only P2. The relaxation parameters obtained by the Arrhenius plots and the evolution with the annealing temperature allow to assign P1 and P2 to an interaction between the dislocations and the solute atoms according to the Darinskiy model.

  15. The effect of venous pulsation on the forehead pulse oximeter wave form as a possible source of error in Spo2 calculation.

    Science.gov (United States)

    Shelley, Kirk H; Tamai, Doris; Jablonka, Denis; Gesquiere, Michael; Stout, Robert G; Silverman, David G

    2005-03-01

    Reflective forehead pulse oximeter sensors have recently been introduced into clinical practice. They reportedly have the advantage of faster response times and immunity to the effects of vasoconstriction. Of concern are reports of signal instability and erroneously low Spo(2) values with some of these new sensors. During a study of the plethysmographic wave forms from various sites (finger, ear, and forehead) it was noted that in some cases the forehead wave form became unexpectedly complex in configuration. The plethysmographic signals from 25 general anesthetic cases were obtained, which revealed the complex forehead wave form during 5 cases. We hypothesized that the complex wave form was attributable to an underlying venous signal. It was determined that the use of a pressure dressing over the sensor resulted in a return of a normal plethysmographic wave form. Further examination of the complex forehead wave form reveal a morphology consistent with a central venous trace with atrial, cuspidal, and venous waves. It is speculated that the presence of the venous signal is the source of the problems reported with the forehead sensors. It is believed that the venous wave form is a result of the method of attachment rather than the use of reflective plethysmographic sensors.

  16. High-temperature and low-stress creep anisotropy of single-crystal superalloys

    Czech Academy of Sciences Publication Activity Database

    Jacome, L. A.; Nortershauser, P.; Heyer, J. K.; Lahni, A.; Frenzel, J.; Dlouhý, Antonín; Somsen, C.; Eggeler, G.

    2013-01-01

    Roč. 61, č. 8 (2013), s. 2926-2943 ISSN 1359-6454 R&D Projects: GA ČR(CZ) GA202/09/2073 Institutional support: RVO:68081723 Keywords : superalloy single crystals * creep anisotropy * rafting * dislocations * deformation mechanisms Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.940, year: 2013

  17. Temperature dependence of Ce:YAG single-crystal phosphors for high-brightness white LEDs/LDs

    Science.gov (United States)

    Arjoca, Stelian; Víllora, Encarnación G.; Inomata, Daisuke; Aoki, Kazuo; Sugahara, Yoshiyuki; Shimamura, Kiyoshi

    2015-05-01

    The growth of Ce:Y3Al5O12(Ce:YAG) single-crystal phosphors (SCPs) by the Czochralski technique is analyzed in terms of segregation coefficient, solubility and absorption cross-section. The emission characteristics of these SCPs are investigated in a wide temperature range, from liquid He temperature up to 500 °C. The internal quantum efficiency of SCPs achieves its maximum at about 250 °C. Thermal quenching of SCPs at high temperature is attributed to the Mott-Seitz mechanism. In the case of ceramic powder phosphors, a continuous droop is observed with the temperature due to defect-related non-radiative recombination paths. It is shown that (Ce:YAG SCPs + blue LEDs/LDs) can cover a wide range of color temperatures 5500-7000 K, with color rendering indices around 70. In conclusion, it is shown that Ce:YAG SCPs are the most efficient and temperature stable converters to fabricate high-brightness white light sources with high-power blue LEDs and LDs.

  18. Development of a new micro-furnace for "in situ" high-temperature single crystal X-ray diffraction measurements

    Science.gov (United States)

    Alvaro, Matteo; Angel, Ross J.; Marciano, Claudio; Zaffiro, Gabriele; Scandolo, Lorenzo; Mazzucchelli, Mattia L.; Milani, Sula; Rustioni, Greta; Domeneghetti, Chiara M.; Nestola, Fabrizio

    2015-04-01

    Several experimental methods to reliably determine elastic properties of minerals at non-ambient conditions have been developed. In particular, different techniques for generating high-pressure and high-temperature have been successfully adopted for single-crystal and powder X-ray diffraction measurements. High temperature devices for "in-situ" measurements should provide the most controlled isothermal environment as possible across the entire sample. It is intuitive that in general, thermal gradients across the sample increase as the temperature increases. Even if the small isothermal volume required for single-crystal X-ray diffraction experiments makes such phenomena almost negligible, the design of a furnace should also aim to reduce thermal gradients by including a large thermal mass that encloses the sample. However this solution often leads to complex design that results in a restricted access to reciprocal space or attenuation of the incident or diffracted intensity (with consequent reduction of the accuracy and/or precision in lattice parameter determination). Here we present a newly-developed H-shaped Pt-Pt/Rh resistance microfurnace for in-situ high-temperature single-crystal X-ray diffraction measurements. The compact design of the furnace together with the long collimator-sample-detector distance allows us to perform measurements up to 2θ = 70° with no further restrictions on any other angular movement. The microfurnace is equipped with a water cooling system that allows a constant thermal gradient to be maintained that in turn guarantees thermal stability with oscillations smaller than 5°C in the whole range of operating T of room-T to 1200°C. The furnace has been built for use with a conventional 4-circle Eulerian geometry equipped with point detector and automated with the SINGLE software (Angel and Finger 2011) that allows the effects of crystal offsets and diffractometer aberrations to be eliminated from the refined peak positions by the 8

  19. Effect of reactor neutron radiation and temperature on the structure of InP single crystals

    International Nuclear Information System (INIS)

    Bojko, V.M.; Kolin, N.G.; Merkurisov, D.I.; Bublik, V.T.; Voronova, M.I.; Shcherbachev, K.D.

    2006-01-01

    The structural characteristics of InP single crystals have been investigated depending on the radiation effects produced by fast and full spectrum neutrons and subsequent heat treatment. A lattice period in InP single crystals decreases under neutron irradiation. Fast neutrons make the main contribution into the change of the lattice period. Availability of the thermal neutrons initiates the formation of Sn atoms, but does not make a significant influence on the change of the lattice period. Heat treatment of the irradiated samples up to 600 deg C causes the annealing of radiation defects and recovery of the lattice period. With increasing neutron fluences a lattice period becomes even higher than before irradiation [ru

  20. Pyroelectric Properties of Potassium and Rubidium Titanyl-Arsenate Single Crystals in the Temperature Range of 4.2-300 K

    International Nuclear Information System (INIS)

    Shaldin, Yu. V.; Matyjasik, S.; Novikova, N. E.; Tseitlin, M.; Mozhaev, E.; Roth, M.

    2010-01-01

    The temperature dependences of the pyroelectric coefficients of KTiOAsO 4 and RbTiOAsO 4 single crystals grown by flux crystallization have been investigated in the temperature range of 4.2-300 K. With an increase in temperature, superionic conductivity first arises in KTiOAsO4 (at T > 200 K) and then (at T > 270 K) in RbTiOAsO 4 . This conductivity is much higher in the samples polarized at T = 4.2 K. An exponential change in the crystal resistivity along the polar direction is simultaneously observed. The results of measurements in the range of 4.2-200 K indicate larger values of pyroelectric coefficients when compared with potassium and rubidium titanyl-phosphate crystals. A correlation between the pyroelectric coefficients and a change in the lattice constants at isomorphic substitutions of K atoms for Rb and P atoms for As has been revealed within the symmetry approach.

  1. Auger electron spectroscopy analysis for growth interface of cubic boron nitride single crystals synthesized under high pressure and high temperature

    Science.gov (United States)

    Lv, Meizhe; Xu, Bin; Cai, Lichao; Guo, Xiaofei; Yuan, Xingdong

    2018-05-01

    After rapid cooling, cubic boron nitride (c-BN) single crystals synthesized under high pressure and high temperature (HPHT) are wrapped in the white film powders which are defined as growth interface. In order to make clear that the transition mechanism of c-BN single crystals, the variation of B and N atomic hybrid states in the growth interface is analyzed with the help of auger electron spectroscopy in the Li-based system. It is found that the sp2 fractions of B and N atoms decreases, and their sp3 fractions increases from the outer to the inner in the growth interface. In addition, Lithium nitride (Li3N) are not found in the growth interface by X-ray diffraction (XRD) experiment. It is suggested that lithium boron nitride (Li3BN2) is produced by the reaction of hexagonal boron nitride (h-BN) and Li3N at the first step, and then B and N atoms transform from sp2 into sp3 state with the catalysis of Li3BN2 in c-BN single crystals synthesis process.

  2. Interaction of high cycle fatigue with high temperature creep in superalloy single crystals

    Czech Academy of Sciences Publication Activity Database

    Lukáš, Petr; Kunz, Ludvík; Svoboda, Milan

    2002-01-01

    Roč. 93, č. 7 (2002), s. 661-665 ISSN 0044-3093 R&D Projects: GA AV ČR IAA2041002; GA AV ČR KSK1010104 Institutional research plan: CEZ:AV0Z2041904 Keywords : Single crystals * Creep/fatigue interaction * Persistent slip bands Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 0.636, year: 2002

  3. Crystallization and segregation in vitreous rutile films annealed at high temperature

    International Nuclear Information System (INIS)

    Omari, M.A.; Sorbello, R.S.; Aita, C.R.

    2005-01-01

    Vitreous titania films with rutile short-range order were sputter deposited on unheated fused silica substrates, sequentially annealed at 973 and 1273 K, and examined by Raman microscopy, scanning electron microscopy, and x-ray diffraction. A segregated microstructure developed after the 1273 K anneal. This microstructure consists of supermicron-size craters dispersed in a matrix of submicron rutile crystals. Ti-O short-range order in the craters is characteristic of a mixture of two high pressure phases, m-TiO 2 (monoclinic P2 1 /c space group) and α-TiO 2 (tetragonal Pbcn space group). We calculated that a high average compressive stress parallel to the substrate must be accommodated in the films at 1273 K, caused by the difference in the thermal expansion coefficients of titania and fused silica. The formation of the segregated microstructure is modeled by considering two processes at work at 1273 K to lower a film's internal energy: crystallization and nonuniform stress relief. The Gibbs-Thomson relation shows that small m-TiO 2 crystallites are able to form directly from vitreous TiO 2 at 1273 K. However, the preferred mechanism for forming α-TiO 2 is likely to be by epitaxial growth at crystalline rutile twin boundaries (secondary crystallization). Both phases are denser than crystalline rutile and reduce the average thermal stress in the films

  4. Study of the temperature evolution of defect agglomerates in neutron irradiated molybdenum single crystals

    International Nuclear Information System (INIS)

    Lambri, O.A.; Zelada-Lambri, G.I.; Cuello, G.J.; Bozzano, P.B.; Garcia, J.A.

    2009-01-01

    Small angle neutron scattering as a function of temperature, differential thermal analysis, electrical resistivity and transmission electron microscopy studies have been performed in low rate neutron irradiated single crystalline molybdenum, at room temperature, for checking the evolution of the defects agglomerates in the temperature interval between room temperature and 1200 K. The onset of vacancies mobility was found to happen in temperatures within the stage III of recovery. At around 550 K, the agglomerates of vacancies achieve the largest size, as determined from the Guinier approximation for spherical particles. In addition, the decrease of the vacancy concentration together with the dissolution of the agglomerates at temperatures higher than around 920 K was observed, which produce the release of internal stresses in the structure.

  5. Study of the temperature evolution of defect agglomerates in neutron irradiated molybdenum single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lambri, O.A. [Instituto de Fisica Rosario. Member of the CONICET' s Research Staff, Avda. Pellegrini 250, (2000) Rosario, Santa Fe (Argentina); Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Laboratorio de Materiales, Escuela de Ingenieria Electrica, Avda. Pellegrini 250, (2000) Rosario, Santa Fe (Argentina)], E-mail: olambri@fceia.unr.edu.ar; Zelada-Lambri, G.I. [Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Laboratorio de Materiales, Escuela de Ingenieria Electrica, Avda. Pellegrini 250, (2000) Rosario, Santa Fe (Argentina); Cuello, G.J. [Institut Laue Langevin, 6, rue Jules Horowitz, BP 156, 38042 Grenoble (France); Departamento de Fisica Aplicada II, Facultad de Ciencias y Tecnologia, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao, Pais Vasco (Spain); Bozzano, P.B. [Laboratorio de Microscopia Electronica. Unidad de Actividad Materiales, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Avda. Gral. Paz 1499, (1650) San Martin (Argentina); Garcia, J.A. [Departamento de Fisica Aplicada II, Facultad de Ciencias y Tecnologia, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao, Pais Vasco (Spain)

    2009-04-15

    Small angle neutron scattering as a function of temperature, differential thermal analysis, electrical resistivity and transmission electron microscopy studies have been performed in low rate neutron irradiated single crystalline molybdenum, at room temperature, for checking the evolution of the defects agglomerates in the temperature interval between room temperature and 1200 K. The onset of vacancies mobility was found to happen in temperatures within the stage III of recovery. At around 550 K, the agglomerates of vacancies achieve the largest size, as determined from the Guinier approximation for spherical particles. In addition, the decrease of the vacancy concentration together with the dissolution of the agglomerates at temperatures higher than around 920 K was observed, which produce the release of internal stresses in the structure.

  6. Design, Manufacturing, and In Vitro Testing of a Patient-Specific Shape-Memory Expander for Nose Reconstruction With Forehead Flap Technique.

    Science.gov (United States)

    Borghi, Alessandro; Rodgers, Will; Schievano, Silvia; Ponniah, Allan; O'Hara, Justine; Jeelani, Owase; Dunaway, David

    2016-01-01

    Forehead skin is widely acknowledged as a good donor site for total nasal reconstruction, thanks to its matching color, texture, and abundant vascularity. The forehead flap technique uses an axial pattern flap forehead skin to replace missing nasal tissue. To increase the amount of available tissue and reduce the size of the tissue defect after flap mobilization, tissue expanders may be used. Although this is a relatively established technique, limitations include reduced moldability of the forehead skin (which is thicker than the nasal skin), and the need for multiple sessions of expansion to achieve a sufficient yield to close the forehead.Shape-memory metals, such as nitinol, can be programmed to "remember" complex shapes. In this work, the methodology for producing a prototype of nitinol tissue expander able to mold the skin in a predetermined patient-specific skin shape is described. A realistic nose mold was manufactured using metal rapid prototyping; nitinol sheet and mesh were molded into nose-shape constructs, having hyperelastic as well as shape-memory capability. Computed tomography scanning was performed to assess the ability of the structure to regain its shape after phase transformation upon cooling within 2% of initial dimensions. The prototypes were implanted in a pig forehead to test its ability to impose a nose shape to the forehead skin.The shape-memory properties of nitinol offer the possibility of producing bespoke tissue expanders able to deliver complex, precisely designed skin envelopes. The hyperelastic properties of nitinol allow constant preprogrammed expansion forces to be generated throughout the expansion process.

  7. Low-temperature phase transition in γ-glycine single crystal. Pyroelectric, piezoelectric, dielectric and elastic properties

    Energy Technology Data Exchange (ETDEWEB)

    Tylczyński, Zbigniew, E-mail: zbigtyl@amu.edu.pl [Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Busz, Piotr [Institute of Molecular Physics, Polish Academy of Science, Smoluchowskiego 17, 60-179 Poznań (Poland)

    2016-11-01

    Temperature changes in the pyroelectric, piezoelectric, elastic and dielectric properties of γ-glycine crystals were studied in the range 100 ÷ 385 K. The pyroelectric coefficient increases monotonically in this temperature range and its value at RT was compared with that of other crystals having glycine molecules. A big maximum in the d14 component of piezoelectric tensor compared by maximum in attenuation of the resonant face-shear mode were observed at 189 K. The components of the elastic stiffness tensor and other components of the piezoelectric tensor show anomalies at this temperature. The components of electromechanical coupling coefficient determined indicate that γ-glycine is a weak piezoelectric. The real and imaginary part of the dielectric constant measured in the direction perpendicular to the trigonal axis show the relaxation anomalies much before 198 K and the activation energies were calculated. These anomalies were interpreted as a result of changes in the NH{sub 3}{sup +} vibrations through electron-phonon coupling of the so called “dynamical transition”. The anomalies of dielectric constant ε*{sub 11} and piezoelectric tensor component d{sub 14} taking place at 335 K are associated with an increase in ac conductivity caused by charge transfer of protons. - Graphical abstract: Imaginary part of dielectric constant in [100] direction. - Highlights: • Piezoelectric, elastic and dielectric constants anomalies were discovered at 189 K. • These anomalies were interpreted as a result of so called “dynamical transition”. • Relaxational dielectric anomaly was explained by the dynamics of glycine molecules. • Pyroelectric coefficient of γ-glycine was determined in a wide temperature range. • Complex dielectric & piezoelectric anomalies at 335 K were caused by protons hopping.

  8. Temperature influence on spectroscopic properties and 2.7-μm lasing of Er:YAP crystal

    Science.gov (United States)

    Švejkar, Richard; Šulc, Jan; Němec, Michal; Jelínková, Helena; Nejezchleb, Karel; Čech, Miroslav

    2018-02-01

    The spectroscopic and laser properties of Er:YAP crystal, that is appropriate for generation at 2.7 μm, in temperature range 78 - 400 K are presented. The sample of Er:YAP (1 at. % of Er3+) had face-polished plan-parallel faces without anti-reflection coatings (thickness 4.47 mm). During experiments the Er:YAP was attached to temperature controlled copper holder and it was placed in vacuum chamber. The transmission and emission spectra together with the fluorescence decay time were measured depending on temperature. The Er:YAP crystal was longitudinally pumped by radiation from laser diode that works in pulse regime (repetition rate 66.6 Hz, pulse duration 1.5 ms, pump wavelength 972.5 nm) or in CW regime. Laser resonator was hemispherical, 145 mm in length with flat pumping mirror (HR @ 2.7 μm) and spherical output coupler (r = 150 mm, R = 95 % @ 2.5 - 2.8 μm). The fluorescence decay time of manifold 4I11/2 (upper laser level) became shorter and intensity of up-conversion radiation was increasing with decreasing temperature. In pulsed regime, the highest slope efficiency with respect to absorbed mean power was 1.27 % at 78 K. The maximum output of mean power was 3.5 mW at 78 K, i.e. 8.7 times higher than measured this value at 300 K. The maximal output power 27 mW with slope efficiency up to 3.5 % was achieved in CW. The radiation generated by Er:YAP laser (2.73 μm) is close to absorption peak of water (3 μm) thus this wavelength can be use in medicine and spectroscopy.

  9. Discovery of room-temperature spin-glass behaviors in two-dimensional oriented attached single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ji; Chen, Kezheng, E-mail: kchen@qust.edu.cn

    2016-05-15

    In this study, room-temperature spin-glass behaviors were observed in flake-like oriented attached hematite (α-Fe{sub 2}O{sub 3}) and iron phosphate hydroxide hydrate (Fe{sub 5}(PO{sub 4}){sub 4}(OH){sub 3}·2H{sub 2}O) single crystals. Remarkably, their coercivity (H{sub C}) values were found to be almost invariable at various given temperatures from 5 to 300 K. The spin topographic map in these flakes was assumed as superparamagnetic (SPM) “islands” isolated by spin glass (SG)-like “bridges”. A spin-glass model was then proposed to demonstrate the spin frustration within these “bridges”, which were formed by the staggered atomic planes in the uneven surfaces belonging to different attached nanoparticles. Under the spatial limitation and coupling shield of these “bridges”, the SPM “islands” were found to be collectively frozen to form a superspin glass (SSG) state below 80 K in weak applied magnetic fields; whereas, when strong magnetic fields were applied, the magnetic coupling of these “islands” would become superferromagnetic (SFM) through tunneling superexchange, so that, these SFM spins could antiferromagnetically couple with the SG-like “bridges” to yield pronounced exchange bias (EB) effect. - Highlights: • Room-temperature spin-glass state was found in 2D oriented attached single crystals. • Coercivity values were found to be almost invariable at different temperatures. • The spin topographic map was assumed as SPM “islands” isolated by SG-like “bridges”.

  10. Hydrostatic pressure and temperature effect on the Raman spectra of the molecular crystal 2-amine-1,3,4-thiadiazole

    Science.gov (United States)

    de Toledo, T. A.; da Costa, R. C.; Bento, R. R. F.; Pizani, P. S.

    2018-03-01

    The structural, thermal and vibrational properties of the molecular crystal 2-amine-1,3,4-thiadiazole (ATD) were investigated combining X-ray diffraction, infrared spectroscopy, Raman scattering (in solid and in solution) and thermal analysis as experimental techniques and first principle calculations based on density functional theory using PZ, BLYP in condensed-phase and B3LYP/cc-pVTZ in isolated molecule methods. The structural stability and phonon anharmonicity were also studied using Raman spectroscopy at different temperatures and hydrostatic pressures. A reasonable agreement was obtained between calculated and experimental results. The main difference between experimental and computed structural and vibrational spectra occurred in the intermolecular bond distance Nsbnd H⋯N and stretching modes of NH2. The vibrational spectra were interpreted and assigned based on group theory and functional group analysis assisted by theoretical results, which led to a more comprehensive knowledge about external and internal modes at different thermodynamic conditions. As temperature increases, it was observed the line-width increases and red-shifts, indicating a phonon anharmonicity without a temperature-induced phase transition in the range 10-413 K. However, ATD crystal undergoes a phase transition in the temperature range 413-475 K, as indicated by thermal analysis curve and Raman spectra. Furthermore, increasing pressure from ambient to 3.1 GPa, it was observed the splitting of the external Raman bands centered at 122 cm-1 (at 0.2 GPa), 112 cm-1 (1.1 GPa), 93 cm-1 (2.4 GPa) in two components as well as the appearance of new band near 50 cm-1 at 1.1 GPa, indicating a possible phase-transition. The blue-shift of the Raman bands was associated to anharmonicity of the interatomic potential caused by unit cell contraction.

  11. Synthesis of indium oxide cubic crystals by modified hydrothermal route for application in room temperature flexible ethanol sensors

    Energy Technology Data Exchange (ETDEWEB)

    Seetha, M., E-mail: seetha.phy@gmail.com [Department of Physics, SRM University, Kattankulathur, Kancheepuram Dt 603 203 (India); Meena, P. [Department of Physics, PSGR Krishnammal College for Women, Coimbatore 641 046 (India); Mangalaraj, D., E-mail: dmraj800@yahoo.com [DRDO-BU Centre for Life Sciences, Bharathiar University Campus, Coimbatore (India); Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 014 (India); Masuda, Yoshitake [National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan); Senthil, K. [School of Advanced Materials Science and Engineering, Sungkyunkwan University (Suwon Campus), Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer For the first time HMT is used in the preparation of indium oxide. Black-Right-Pointing-Pointer HMT itself acts as base for the precursor and results in cubic indium hydroxide. Black-Right-Pointing-Pointer Modified hydrothermal route used for the preparation of cubic indium oxide crystals. Black-Right-Pointing-Pointer As a new approach a composite film synthesized with prepared indium oxide. Black-Right-Pointing-Pointer Film showed good response to ethanol vapours with quick response and recovery times. - Abstract: Indium oxide cubic crystals were prepared by using hexamethylenetetramine and indium chloride without the addition of any structure directing agents. The chemical route followed in the present work was a modified hydrothermal synthesis. The average crystallite size of the prepared cubes was found to be 40 nm. A blue emission at 418 nm was observed at room temperature when the sample was excited with a 380 nm Xenon lamp. This emission due to oxygen vacancies made the material suitable for gas sensing applications. The synthesized material was made as a composite film with polyvinyl alcohol which was more flexible than the films prepared on glass substrates. This flexible film was used as a sensing element and tested with ethanol vapours at room temperature. The film showed fast response as well as recovery to ethanol vapours with a sensor response of about 1.4 for 100 ppm of the gas.

  12. Synthesis of indium oxide cubic crystals by modified hydrothermal route for application in room temperature flexible ethanol sensors

    International Nuclear Information System (INIS)

    Seetha, M.; Meena, P.; Mangalaraj, D.; Masuda, Yoshitake; Senthil, K.

    2012-01-01

    Highlights: ► For the first time HMT is used in the preparation of indium oxide. ► HMT itself acts as base for the precursor and results in cubic indium hydroxide. ► Modified hydrothermal route used for the preparation of cubic indium oxide crystals. ► As a new approach a composite film synthesized with prepared indium oxide. ► Film showed good response to ethanol vapours with quick response and recovery times. - Abstract: Indium oxide cubic crystals were prepared by using hexamethylenetetramine and indium chloride without the addition of any structure directing agents. The chemical route followed in the present work was a modified hydrothermal synthesis. The average crystallite size of the prepared cubes was found to be 40 nm. A blue emission at 418 nm was observed at room temperature when the sample was excited with a 380 nm Xenon lamp. This emission due to oxygen vacancies made the material suitable for gas sensing applications. The synthesized material was made as a composite film with polyvinyl alcohol which was more flexible than the films prepared on glass substrates. This flexible film was used as a sensing element and tested with ethanol vapours at room temperature. The film showed fast response as well as recovery to ethanol vapours with a sensor response of about 1.4 for 100 ppm of the gas.

  13. Temperature-touch interaction: Weber's phenomenon revisited.

    Science.gov (United States)

    Stevens, J C; Green, B G

    1978-09-01

    The six experiments reported here stemmed from Weber's (E. H. Weber, In R. Wagner (Ed.), Handwnörterbuch der Physiologie, 1846. Vol. 3, pp. 481-588) report that cold objects on the forehead feel heavier than warm ones, implying an effect of temperature on the touch modality. The experiments arrived at first-order answers to how temperature, force of stimulation, areal size of stimulation, and body locus might influence the magnitude of touch sensation. Typically, concomitant cooling greatly intensifies touch magnitude as perceived via the forehead and the forearm. Warning has little or no effect via the forehead but gives a significant intensification (less pronounced than that of cooling) on the forearm. When the areal size of the stimulation becomes very small, the intensification effects cannot be reliably demonstrated. The findings are reviewed in the light of what is known about the physiology of the cutaneous nerves.

  14. The non-exponential relaxation of the C60 crystal around glass transition temperature

    International Nuclear Information System (INIS)

    Yan, F; Wang, Y.N.

    1999-01-01

    A model of the energy barrier of a molecule between two orientational states in the C 60 crystal, which depends on the neighboring molecules, is first proposed. Based on this model, the orientational relaxation of C 60 molecules around 90 K was simulated with the Monte Carlo method. The simulation results show that the relaxation is slightly non-exponential and can fit the Kohlrausch-Williams-Watts function with the non-exponential factor β = 0.962 ± 0.002, which is equal to the experimental data that has not been explained before. (orig.)

  15. Effect of heat-treatment on microstructure and high-temperature deformation behavior of a low rhenium-containing single crystal nickel-based superalloy

    International Nuclear Information System (INIS)

    Sun, Nairong; Zhang, Lanting; Li, Zhigang; Shan, Aidang

    2014-01-01

    A low rhenium-containing [001] oriented single crystal nickel-based superalloy with different γ′ morphologies induced by various aging treatments was compressed from room temperature to 1000 °C. All the single crystal samples with different γ′ morphologies exhibit anomalous yield behavior. The sample first aged at 1180 °C has the widest anomalous temperature domain and highest yield strengths. The sample first aged at 1000 °C has the highest anomalous peak stress temperature

  16. Thermal expansion behavior of empressite, AgTe: A structural study by means of in situ high-temperature single-crystal X-ray diffraction

    International Nuclear Information System (INIS)

    Bindi, Luca

    2009-01-01

    The crystal structure of empressite, AgTe, a rare silver telluride, has been investigated by in situ X-ray single-crystal diffraction methods within the temperature range 298-463 K. AgTe remains orthorhombic, space group Pmnb (Pnma as standard), and shows only normal thermal expansion over the entire temperature range. The unit-cell parameters show a gradual increase with the increase of temperature. Slight adjustments in the geometry of Ag-tetrahedra and in the crystal-chemical environment of tellurium atoms occur in a continuous way without abrupt structural changes. The coefficients of thermal expansion along various axes are: α a = 1.5 x 10 -5 K -1 , α b = 3.0 x 10 -5 K -1 , α c = 2.2 x 10 -5 K -1 , and the bulk thermal expansion coefficient α V is 5.4 x 10 -5 K -1 for the temperature range 298-463 K

  17. Cyclic deformation of NI/sub 3/(Al,Nb) single crystals at ambient and elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Bonda, N.R.

    1985-01-01

    Cyclic tests were performed on Ni/sub 3/(Al,Nb) (..gamma..' phase) single crystals by using a servo-hydraulic machine under fully reversed plastic strain control at a frequency of 0.1-0.2 Hz at room temperature, 400/sup 0/C and 700/sup 0/C. Since the monotonic behavior is orientation dependent, three orientations were studied. Asymmetry in tensile and compressive stresses was observed in the cyclic hardening curves of specimens tested at these temperatures and they were discussed with regard to the model suggested by Paider et al for monotonic behavior. The stress levels in the cyclic stress-strain curves (CSSC) at room temperature depended on orientation and cyclic history. No CSSCs were established at 400/sup 0/C and 700/sup 0/C. The deformation in cyclic tests at small plastic strain amplitudes was found to be different from that in monotonic tests in the microplastic regions in which the deformation is believed to be carried by a small density of edge dislocations. But in cyclic deformation, to and from motion of dislocations trap the edge dislocations into dipoles and therefore screw dislocations will be forced to participate in the deformation. Cracks on the surfaces of specimens tested at room temperature and 400/sup 0/C were found to be of stage I type, whereas at 700/sup 0/C, they were of stage II type.

  18. Room-temperature serial crystallography using a kinetically optimized microfluidic device for protein crystallization and on-chip X-ray diffraction

    Directory of Open Access Journals (Sweden)

    Michael Heymann

    2014-09-01

    Full Text Available An emulsion-based serial crystallographic technology has been developed, in which nanolitre-sized droplets of protein solution are encapsulated in oil and stabilized by surfactant. Once the first crystal in a drop is nucleated, the small volume generates a negative feedback mechanism that lowers the supersaturation. This mechanism is exploited to produce one crystal per drop. Diffraction data are measured, one crystal at a time, from a series of room-temperature crystals stored on an X-ray semi-transparent microfluidic chip, and a 93% complete data set is obtained by merging single diffraction frames taken from different unoriented crystals. As proof of concept, the structure of glucose isomerase was solved to 2.1 Å, demonstrating the feasibility of high-throughput serial X-ray crystallography using synchrotron radiation.

  19. Growth of (CH 3) 2NH 2CuCl 3 single crystals using evaporation method with different temperatures and solvents

    Science.gov (United States)

    Chen, L. M.; Tao, W.; Zhao, Z. Y.; Li, Q. J.; Ke, W. P.; Wang, X. M.; Liu, X. G.; Fan, C.; Sun, X. F.

    2010-10-01

    The bulk single crystals of low-dimensional magnet (CH 3) 2NH 2CuCl 3 (DMACuCl 3 or MCCL) are grown by a slow evaporation method with different kinds of solvents, different degrees of super-saturation of solution and different temperatures of solution, respectively. Among three kinds of solvent, methanol, alcohol and water, alcohol is found to be the best one for growing MCCL crystals because of its structural similarity to the raw materials and suitable evaporation rate. The best growth temperature is in the vicinity of 35 °C. The problem of the crystals deliquescing in air has been solved through recrystallization process. The crystals are characterized by means of X-ray diffraction, specific heat and magnetic susceptibility.

  20. P-type poly-Si prepared by low-temperature aluminum-induced crystallization and doping for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Yasuhiro; Yu, Zhenrui; Morales-Acevedo, Arturo [CINVESTAV-IPN, Mexico, D.F. (Mexico)

    2000-07-01

    P-type poly-Si thin films prepared by low temperature aluminum-induced crystallization and doping are reported. The starting material was boron-doped a-Si:H prepared by PECVD on glass substrates. Aluminum layers with different thickness were evaporated on a-Si:H surface and conventional thermal annealing was performed at temperatures ranging from 300 to 550 Celsius degrees. XRD, SIMS, and Hall effect measurements were carried out to characterize the annealed Al could be crystallized at temperature as low as 300 Celsius degrees in 60 minutes. This material has high carrier concentration as well as high Hall mobility and can be used as a p-layer of seed layer for thin film poly-Si solar cells. The technique reported here is compatible with PECVD process. [Spanish] Se informa sobre la preparacion de peliculas delgadas tipo P y Poli-Si mediante la cristalizacion inducida de aluminio a baja temperatura y el dopado. El material inicial era de boro dopado y a-Si:H preparado PECVD sobre substratos de vidrio. Se evaporaron capas de aluminio de diferente espesor sobre una superficie de a-Si:H y se llevo a cabo un destemplado termico convencional a temperaturas que varian entre 300 y 500 grados Celsius. Se llevaron a cabo mediciones de XRB, SIMS y del efecto Hall para caracterizar el aluminio destemplado para que pudiera ser cristalizado a temperaturas tan bajas como 300 grados Celsius en 60 minutos. Este material tiene una alta concentracion portadora asi como una alta movilidad Hall y puede usarse como una capa de semilla para celdas solares de pelicula delgada Poli-Si. La tecnica reportada aqui es compatible con el proceso PECVD.

  1. Temperature-dependent adsorption of surfactant molecules and associated crystallization kinetics of noncentrosymmetric Fe(IO{sub 3}){sub 3} nanorods in microemulsions

    Energy Technology Data Exchange (ETDEWEB)

    El-Kass, Moustafa [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Ladj, Rachid [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Université Lyon1, CNRS, UMR 5007, LAGEP, CPE, 43 bd 11 Novembre 1918, F-69622 Villeurbanne (France); Mugnier, Yannick, E-mail: Yannick.Mugnier@univ-savoie.fr [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Le Dantec, Ronan [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Hadji, Rachid [Institut Jean Lamour, UMR CNRS n°7198, Université de Lorraine, Nancy 1, BP 239, 54506 Vandoeuvre-lès-Nancy Cedex (France); Marty, Jean-Christophe [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Rouxel, Didier [Institut Jean Lamour, UMR CNRS n°7198, Université de Lorraine, Nancy 1, BP 239, 54506 Vandoeuvre-lès-Nancy Cedex (France); Durand, Christiane [Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy Le Vieux Cedex (France); Fontvieille, Dominique [UMR CARRTEL (INRA/Université de Savoie), Laboratoire de Microbiologie Aquatique, BP 511, 74203 Thonon Cedex (France); Rogalska, Ewa [Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565, Nancy Université, BP 70239, 54506 Vandoeuvre-lès-Nancy cedex (France); and others

    2013-11-15

    Graphical abstract: - Highlights: • Crystallization of Fe(IO{sub 3}){sub 3} in microemulsions probed by hyper-Rayleigh scattering. • A faster growth and a better shape control of nanorods are obtained at 80 °C. • Different persistent cell deformations are related to the crystallization kinetics. • A temperature-dependent adsorption of surfactants on nanorods is suggested. - Abstract: Aggregation-induced crystallization of iron iodate nanorods within organic–inorganic aggregates of primary amorphous precursors is probed by time-dependent hyper-Rayleigh scattering measurements in Triton X-100 based-microemulsions. In the context of a growing interest of noncentrosymmetric oxide nanomaterials in multi-photon bioimaging, we demonstrate by a combination of X-ray diffraction and electron microscopy that an increase in the synthesis of temperature results in faster crystallization kinetics and in a better shape-control of the final Fe(IO{sub 3}){sub 3} nanorods. For initial microemulsions of fixed composition, room-temperature synthesis leads to bundles of 1–3 μm long nanorods, whereas shorter individual nanorods are obtained when the temperature is increased. Results are interpreted in terms of kinetically unfavorable mesoscale transformations due to the strong binding interactions with Triton molecules. The interplay between the nanorod crystallization kinetics and their corresponding unit cell deformation, evidenced by lattice parameter refinements, is attributed to a temperature-dependent adsorption of surfactants molecules at the organic–inorganic interface.

  2. Effect of grain-boundary crystallization on the high-temperature strength of silicon nitride

    Science.gov (United States)

    Pierce, L. A.; Mieskowski, D. M.; Sanders, W. A.

    1986-01-01

    Si3N4 specimens having the composition 88.7 wt pct Si3N4-4.9 wt pct SiO2-6.4 wt pct Y2O3 were sintered at 2140 C under 25 atm N2 for 1 h and then subjected to a 5 h anneal at 1500 C. Crystallization of an amorphous grain-boundary phase resulted in the formation of Y2Si2O7. The short-time 1370 C strength of this material was compared with that of material of the same composition having no annealing treatment. No change in strength was noted. This is attributed to the refractory nature of the yttrium-rich grain-boundary phase (apparently identical in both glassy and crystalline phases) and the subsequent domination of the failure process by common processing flaws.

  3. High-temperature performance of the brazement of molybdenum single crystals

    International Nuclear Information System (INIS)

    Hirakoa, Y.

    1992-01-01

    Molybdenum is utilized in the fields of high-temperature vacuum industry, electrical and electronic industry, and chemical industries. For the wider application of this material, however, it is necessary to obtain a joining with good quality. In this investigation, high-temperature brazing of a single-crystalline molybdenum was performed. Then the bend properties of the brazement after a high-temperature annealing were evaluated. The single-crystalline molybdenum had been produced by the secondary recrystallization method. Brazing was performed in vacuum at 2273K using Mo-40Ru alloy powder as a brazing material. The brazement was investigated via optical microscopy, EPMA, Knoop hardness, and three point bending. In this paper the effects of annealing in hydrogen and vacuum are discussed

  4. Vertical Magnetic Levitation Force Measurement on Single Crystal YBaCuO Bulk at Different Temperatures

    Science.gov (United States)

    Celik, Sukru; Guner, Sait Baris; Ozturk, Kemal; Ozturk, Ozgur

    Magnetic levitation force measurements of HTS samples are performed with the use of liquid nitrogen. It is both convenient and cheap. However, the temperature of the sample cannot be changed (77 K) and there is problem of frost. So, it is necessary to build another type of system to measure the levitation force high Tc superconductor at different temperatures. In this study, we fabricated YBaCuO superconducting by top-seeding-melting-growth (TSMG) technique and measured vertical forces of them at FC (Field Cooling) and ZFC (Zero Field Cooling) regimes by using our new designed magnetic levitation force measurement system. It was used to investigate the three-dimensional levitation force and lateral force in the levitation system consisting of a cylindrical magnet and a permanent cylindrical superconductor at different temperatures (37, 47, 57, 67 and 77 K).

  5. Crystal structure of the high temperature phase of oxidised Pr2NiO4+δ

    International Nuclear Information System (INIS)

    Allancon, C.; Odier, P.; Bassat, J.M.; Loup, J.P.; Fernandez-Diaz, M.T.; Martinez, J.L.

    1996-01-01

    Powder neutron diffraction measurements have been carried out on oxidised Pr 2 NiO 4+δ at high temperature under O 2 atmosphere. A structural transition takes place at about 720 K from an orthorhombic symmetry to a tetragonal one. The high temperature structure has been refined in the P4 2 /ncm space group using a split-atom model for apical oxygens simulating their strong anharmonic motion. The interstitial oxygens occupy the sites (4e) and (8f) following a uniform distribution. The refined occupancy is in good agreement with the value measured by TGA, corresponding to an oxygen excess as high as δ=0.18. (orig.)

  6. Electrical properties of single crystal Yttrium Iron Garnet ultra-thin films at high temperatures

    OpenAIRE

    Thiery, Nicolas; Naletov, Vladimir V.; Vila, Laurent; Marty, Alain; Brenac, Ariel; Jacquot, Jean-François; de Loubens, Grégoire; Viret, Michel; Anane, Abdelmadjid; Cros, Vincent; Youssef, Jamal Ben; Demidov, Vladislav E.; Demokritov, Sergej O.; Klein, Olivier

    2017-01-01

    We report a study on the electrical properties of 19 nm thick Yttrium Iron Garnet (YIG) films grown by liquid phase epitaxy. The electrical conductivity and Hall coefficient are measured in the high temperature range [300,400]~K using a Van der Pauw four-point probe technique. We find that the electrical resistivity decreases exponentially with increasing temperature following an activated behavior corresponding to a band-gap of $E_g\\approx 2$ eV, indicating that epitaxial YIG ultra-thin film...

  7. Sensitivity of the crystal quality of SiGe layers grown at low temperatures by trisilane and germane

    Energy Technology Data Exchange (ETDEWEB)

    Abedin, A., E-mail: aabedin@kth.se; Moeen, M.; Cappetta, C.; Östling, M.; Radamson, H.H., E-mail: rad@kth.se

    2016-08-31

    This work investigates the crystal quality of SiGe layers grown at low temperatures using trisilane, and germane precursors. The crystal quality sensitivity was monitored for hydrogen chloride and/or minor oxygen amount during SiGe epitaxy or at the interface of SiGe/Si layers. The quality of the epi-layers was examined by quantifying noise parameter, K{sub 1/f} obtained from the power spectral density vs. 1/f curves. The results indicate that while it is difficult to detect small defect densities in SiGe layers by physical material characterization, the noise measurement could reveal the effects of oxygen contamination as low as 0.16 mPa inside and in the interface of the layers. - Highlights: • SiGe layers were grown using trisilane and germane. • Effect of HCl flow on Ge content and growth rate was investigated. • O{sub 2} partial pressures up to 4.3 mPa did not affect x-ray diffraction pattern. • O{sub 2} partial pressures as low as 0.16 mPa increased the noise level. • HCl increased metal contaminations of the layers and the noise level consequently.

  8. The influence of cobalt, tantalum, and tungsten on the elevated temperature mechanical properties of single crystal nickel-base superalloys

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1985-01-01

    The influence of composition on the tensile and creep strength of 001-line oriented nickel-base superalloy single crystals at temperatures near 1000 C was investigated. Cobalt, tantalum, and tungsten concentrations were varied according to a matrix of compositions based on the single crystal version of MAR-M247. For alloys with the baseline refractory metal level of 3 wt pct Ta and 10 wt pct W, decreases in Co level from 10 to 0 wt pct resulted in increased tensile and creep strength. Substitution of 2 wt pct W for 3 wt pct Ta resulted in decreased creep life at high stresses, but improved life at low stresses. Substitution of Ni for Ta caused large reductions in tensile strength and creep resistance, and corresponding increases in ductility. For these alloys with low Ta-plus-W totals, strength was independent of Co level. The effects of composition on properties were related to the microstructural features of the alloys. In general, high creep strength was associated with high levels of gamma-prime volume fraction, gamma-gamma-prime lattice mismatch, and solid solution hardening.

  9. Thermodynamic studies on the ferroelectric phase transition in neutron irradiated (LixK1-x)2SO4 crystals at high temperature

    International Nuclear Information System (INIS)

    Kassem, M.E.; El-Khatib, A.M.; Ammar, E.A.; Denton, M.M.

    1989-05-01

    Thermodynamic studies of (Li x K 1-x ) 2 SO 4 , LKS, mixed crystals have been made in the concentration range (x=0.1,0.2,...,x=0.5). The thermal behavior has been investigated by differential thermal analysis, DTA, and differential scanning calorimeter, DSC, in the vicinity of high temperature phases. Also, the effect of the mixed neutron field of fast and thermal neutrons (10% of the reactor neutron pile is fast neutrons) on the thermal properties of mixed crystals was studied. The results showed a change in the transition temperature Tc, as well as the value of specific heat Cp at transition temperature, due to the change of stoichiometric ratio and radiation doses. The change of enthalpy and entropy of mixed crystals have been estimated numerically. The obtained small values of ΔS/R is characteristic of incommensurate phase transition as previously confirmed by the results of neutron diffraction technique. (author). 16 refs, 5 figs, 1 tab

  10. Effects of temperature and void on the dynamics and microstructure of structural transition in single crystal iron

    Science.gov (United States)

    Shao, Jian-Li; Wang, Pei; Zhang, Feng-Guo; He, An-Min

    2018-06-01

    With classic molecular dynamics simulations, we investigate the effects of temperature and void on the bcc to hcp/fcc structural transition in single crystal iron driven by 1D ([0 0 1]) and 3D (uniform) compressions. The results show that the pressure threshold does not reduce monotonously with temperature. The pressure threshold firstly increases and then decreases in the range of 60–360 K under 1D compression, while the variation trend is just opposite under 3D compression. As expected, the initial defect may lower the pressure threshold via heterogenous nucleation. This effect is found to be more distinct at lower temperature, and the heterogenous nucleation mainly results in hcp structure. Under the condition of strain constraint, the products of structural transition will respectively form flaky hcp twin structure ((1 0 0) or (0 1 0)) and lamellar structure ({1 1 0}) of mixed phases under 1D and 3D compressions. During the structural transition, we find the shear stress (1D compression) of hcp phase is always lower than that of bcc phase. The cold energy calculations indicate that the hcp phase is the most stable under high pressure. However, we observe the evident metastable state of bcc phase, whose energy will be much higher than both hcp and fcc phases, and then provides the possibility for the occurrence of fcc nucleation.

  11. Giant volume magnetostriction in the Y{sub 2}Fe{sub 17} single crystal at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, S. A., E-mail: nikitin@phys.msu.ru; Pankratov, N. Yu.; Smarzhevskaya, A. I.; Politova, G. A. [Physics Faculty, Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Pastushenkov, Yu. G., E-mail: yupast@mail.ru; Skokov, K. P. [Physics Faculty, Tver State University, 170100 Tver (Russian Federation); Moral, A. del [Laboratorio de Magnetismo de Slidos, Departamento de Fisica de Materia Condensada and Instituto de Ciencia de Materiales de Aragn, Facultad de Ciencias, Universidad de Zaragoza-C.S.I.C, E-50009 Zaragoza (Spain)

    2015-05-21

    An investigation of the Y{sub 2}Fe{sub 17} compound belonging to the class of intermetallic alloys of rare-earth and 3d-transition metals is presented. The magnetization, magnetostriction, and thermal expansion of the Y{sub 2}Fe{sub 17} single crystal were studied. The forced magnetostriction and magnetostriction constants were investigated in the temperature range of the magnetic ordering close to the room temperature. The giant field induced volume magnetostriction was discovered in the room temperature region in the magnetic field up to 1.2 T. The contributions of both anisotropic single-ion and isotropic pair exchange interactions to the volume magnetostriction and magnetostriction constants were determined. The experimental results were interpreted within the framework of the Standard Theory of Magnetostriction and the Landau thermodynamic theory. It was found out that the giant values of the volume magnetostriction were caused by the strong dependence of the 3d-electron Coulomb charge repulsion on the deformations and width of the 3d-electron energy band.

  12. Deep level centers in electron-irradiated silicon crystals doped with copper at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Yarykin, Nikolai [Institute of Microelectronics Technology, RAS, Chernogolovka (Russian Federation); Weber, Joerg [Technische Universitaet Dresden (Germany)

    2017-07-15

    The effect of bombardment with energetic particles on the deep-level spectrum of copper-contaminated silicon wafers is studied by space charge spectroscopy methods. The p-type FZ-Si wafers were doped with copper in the temperature range of 645-750 C and then irradiated with the 10{sup 15} cm{sup -2} fluence of 5 MeV electrons at room temperature. Only the mobile Cu{sub i} species and the Cu{sub PL} centers are detected in significant concentrations in the non-irradiated Cu-doped wafers. The properties of the irradiated samples are found to qualitatively depend on the copper in-diffusion temperature T{sub diff}. For T{sub diff} > 700 C, the irradiation partially reduces the Cu{sub i} concentration and introduces additional Cu{sub PL} centers while no standard radiation defects are detected. If T{sub diff} was below ∝700 C, the irradiation totally removes the mobile Cu{sub i} species. Instead, the standard radiation defects and their complexes with copper appear in the deep-level spectrum. A model for the defects reaction scheme during the irradiation is derived and discussed. DLTS spectrum of the Cu-contaminated and then irradiated silicon qualitatively depends on the copper in-diffusion temperature. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. High Pressure Low Temperature X-Ray Diffraction Studies of UO2 and UN single crystals.

    Science.gov (United States)

    Antonio, Daniel; Mast, Daniel; Lavina, Barbara; Gofryk, Krzysztof

    Uranium dioxide is the most commonly used nuclear fuel material in commercial reactors, while uranium nitride also has many thermal and physical properties that make it attractive for potential use in reactors. Both have a cubic fcc lattice structure at ambient conditions and transition to antiferromagnetic order at low temperature. UO2 is a Mott insulator that orders in a complex non-collinear 3k magnetic structure at about 30 K, while UN has appreciable conductivity and orders in a simpler 1k magnetic structure below 52 K. Both compounds are characterized by strong magneto-structural interactions, understanding of which is vital for modeling their thermo-physical properties. While UO2 and UN have been extensively studied at and above room temperature, little work has been done to directly study the structure of these materials at low temperatures where magnetic interactions are dominant. In the course of our systematic studies on magneto vibrational behavior of UO2 and UN, here we present our recent results of high pressure X-Ray Diffraction (up to 35 GPa) measured below the Neel temperature using synchrotron radiation. Work supported by the Department of Energy, Office of Basic Energy Sciences, Materials Sciences, and Engineering Division.

  14. Room Temperature Monoclinic Phase in BaTiO3 Single Crystals

    Science.gov (United States)

    Denev, Sava; Kumar, Amit; Barnes, Andrew; Vlahos, Eftihia; Shepard, Gabriella; Gopalan, Venkatraman

    2010-03-01

    BaTiO3 is a well studied ferroelectric material for the last half century. It is well known to show phase transitions to tetragonal, orthorhombic and rhombohedral phases upon cooling. Yet, some old and some recent studies have argued that all these phases co-exist with a second phase with monoclinic distortion. Using optical second harmonic generation (SHG) at room temperature we directly present evidence for such monoclininc phase co-existing with tetragonal phase at room temperature. We observe domains with the expected tetragonal symmetry exhibiting 90^o and 180^o domain walls. However, at points of higher stress at the tips of the interpenetrating tetragonal domains we observe a well pronounced metastable ``staircase pattern'' with a micron-scale fine structure. Polarization studies show that this phase can be explained only by monoclinic symmetry. This phase is very sensitive to external perturbations such as temperature and fields, hence stabilizing this phase at room temperature could lead to large properties' tunability.

  15. The stability of PEMFC electrodes : platinum dissolution vs potential and temperature investigated by quartz crystal microbalance

    NARCIS (Netherlands)

    Dam, V.A.T.; Bruijn, de F.A.

    2007-01-01

    The stability of platinum in proton exchange membrane fuel cell (PEMFC) electrodes has been investigated by determining the dissolution of platinum from a thin platinum film deposited on a gold substrate in 1 M HClO4 at different temperatures ranging between 40 and 80°C and potentials between 0.85

  16. Carbon monoxide oxidation on Pt single crystal electrodes: understanding the catalysis for low temperature fuel cells.

    Science.gov (United States)

    García, Gonzalo; Koper, Marc T M

    2011-08-01

    Herein the general concepts of fuel cells are discussed, with special attention to low temperature fuel cells working in alkaline media. Alkaline low temperature fuel cells could well be one of the energy sources in the next future. This technology has the potential to provide power to portable devices, transportation and stationary sectors. With the aim to solve the principal catalytic problems at the anode of low temperature fuel cells, a fundamental study of the mechanism and kinetics of carbon monoxide as well as water dissociation on stepped platinum surfaces in alkaline medium is discussed and compared with those in acidic media. Furthermore, cations involved as promoters for catalytic surface reactions are also considered. Therefore, the aim of the present work is not only to provide the new fundamental advances in the electrocatalysis field, but also to understand the reactions occurring at fuel cell catalysts, which may help to improve the fabrication of novel electrodes in order to enhance the performance and to decrease the cost of low temperature fuel cells. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Kinetics and mechanisms of low temperature deformation in high purity niobium single crystals

    International Nuclear Information System (INIS)

    Karam, N.H.

    1985-01-01

    This study included three main aspects: (1) an extensive examination of the temperature and strain rate dependence of the flow stress without any thermodynamic analysis; (2) detailed thermodynamic analysis of the experimental data with no specific models involved, and (3) testing the results against specific models as well as modification of Seeger's model (1981-1983) to account for the results. The temperature and strain rate dependence of the tau/sub f/, tau/sup */, and tau/sub μ/ was experimentally determined over the temperature range 300 to 4.2 K with intervals ΔT ≤ 20K. The value of tau/sub μ/(T/sub k/) was found experimentally by decremental unloading, stress relaxation, and back extrapolation techniques giving tau/sub μ/(T/sub k/) = 19 MPa in agreement with the analytical analysis. The knee temperature was found T/sub k/ = 300K and the Peierls stress was determined as taup = 370 MPa. The strain rate sensitivity λ was evaluated using both strain rate cycle and stress relaxation techniques which were in excellent agreement. λ reached its maximum at 77K. Experimental data are best described by double kink nucleation models where deformation occurs by the formation of double kinks on screw dislocations that are resisted by a lattice friction arising from the periodic lattice potential

  18. Defect types and room temperature ferromagnetism in N-doped rutile TiO2 single crystals

    Science.gov (United States)

    Qin, Xiu-Bo; Li, Dong-Xiang; Li, Rui-Qin; Zhang, Peng; Li, Yu-Xiao; Wang, Bao-Yi

    2014-06-01

    The magnetic properties and defect types of virgin and N-doped TiO2 single crystals are probed by superconducting quantum interference device (SQUID), X-ray photoelectron spectroscopy (XPS), and positron annihilation analysis (PAS). Upon N doping, a twofold enhancement of the saturation magnetization is observed. Apparently, this enhancement is not related to an increase in oxygen vacancy, rather to unpaired 3d electrons in Ti3+, arising from titanium vacancies and the replacement of O with N atoms in the rutile structure. The production of titanium vacancies can enhance the room temperature ferromagnetism (RTFM), and substitution of O with N is the onset of ferromagnetism by inducing relatively strong ferromagnetic ordering.

  19. Spontaneous emission of semiconductor quantum dots in inverse opal SiO2 photonic crystals at different temperatures.

    Science.gov (United States)

    Yang, Peng; Yang, Yingshu; Wang, Yinghui; Gao, Jiechao; Sui, Ning; Chi, Xiaochun; Zou, Lu; Zhang, Han-Zhuang

    2016-02-01

    The photoluminescence (PL) characteristics of CdSe quantum dots (QDs) infiltrated into inverse opal SiO2 photonic crystals (PCs) are systemically studied. The special porous structure of inverse opal PCs enhanced the thermal exchange rate between the CdSe QDs and their surrounding environment. Finally, inverse opal SiO2 PCs suppressed the nonlinear PL enhancement of CdSe QDs in PCs excited by a continuum laser and effectively modulated the PL characteristics of CdSe QDs in PCs at high temperatures in comparison with that of CdSe QDs out of PCs. The final results are of benefit in further understanding the role of inverse opal PCs on the PL characteristics of QDs. Copyright © 2015 John Wiley & Sons, Ltd.

  20. Temperature-controlled two new Co(II) compounds with distinct topological networks: Syntheses, crystal structures and catalytic properties

    Science.gov (United States)

    Meng, Qing-Hua; Long, Xu; Liu, Jing-Li; Zhang, Shuan; Zhang, Guang-Hui

    2018-04-01

    Two new Co(II) coordination compounds, namely [Co2(bptc)(bpp)2]n (1) and [Co(bptc)0.5(bpp)]n (2) (H4bptc = biphenyl-3,3‧,5,5‧-tetracarboxylic acid, bpp = 1,3-di(4-pyridyl)propane), have been hydrothermally synthesized from the same reactants via tuning the reaction temperature. Single crystal X-ray diffraction analyses revealed that both 1 and 2 feature 2D sheet motifs. Topological analyses revealed that compounds 1 and 2 show distinct topological networks. Under the weak Van der Waals interactions, the 2D sheet motifs of compounds 1 and 2 are further packed into 2D→3D interdigitated supramolecular frameworks. Moreover, the two Co(II) compounds show high catalytic activities for degradation of methyl orange (MO) in a Fenten-like process.

  1. Effect of irradiation temperature on crystallization of {alpha}-Fe induced by He irradiations in Fe{sub 80}B{sub 20} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    San-noo, Toshimasa; Toriyama, Tamotsu; Wakabayashi, Hidehiko; Iijima, Hiroshi [Musashi Inst. of Tech., Tokyo (Japan); Hayashi, Nobuyuki; Sakamoto, Isao

    1997-03-01

    Since amorphous alloys are generally highly resistant to irradiation and their critical radiation dose is an order of magnitude higher for Fe-B amorphous alloy than Mo-methods, these alloys are expected to become applicable as for fusion reactor materials. The authors investigated {alpha}-Fe crystallization in an amorphous alloy, Fe{sub 80}B{sub 20} using internal conversion electron Moessbauer spectroscopy. The amount of {alpha}-Fe component was found to increase by raising the He-irradiation dose. The target part was modified to enable He ion radiation at a lower temperature (below 400 K) by cooling with Peltier element. Fe{sub 80}B{sub 20} amorphous alloy was cooled to keep the temperature at 300 K and exposed to 40 keV He ion at 1-3 x 10{sup 8} ions/cm{sup 2}. The amount of {alpha}-Fe crystal in each sample was determined. The crystal formation was not observed for He ion radiation below 2 x 10{sup 18} ions/cm{sup 2}, but that at 3 x 10{sup 8} ions/ cm{sup 2} produced a new phase ({delta} +0.40 mm/sec, {Delta} = 0.89 mm/sec). The decrease in the radiation temperature from 430 to 300 K resulted to extremely repress the production of {alpha}-Fe crystal, suggesting that the crystallization induced by He-radiation cascade is highly depending on the radiation temperature. (M.N.)

  2. Order-parameter-aided temperature-accelerated sampling for the exploration of crystal polymorphism and solid-liquid phase transitions

    International Nuclear Information System (INIS)

    Yu, Tang-Qing; Vanden-Eijnden, Eric; Chen, Pei-Yang; Chen, Ming; Samanta, Amit; Tuckerman, Mark

    2014-01-01

    The problem of predicting polymorphism in atomic and molecular crystals constitutes a significant challenge both experimentally and theoretically. From the theoretical viewpoint, polymorphism prediction falls into the general class of problems characterized by an underlying rough energy landscape, and consequently, free energy based enhanced sampling approaches can be brought to bear on the problem. In this paper, we build on a scheme previously introduced by two of the authors in which the lengths and angles of the supercell are targeted for enhanced sampling via temperature accelerated adiabatic free energy dynamics [T. Q. Yu and M. E. Tuckerman, Phys. Rev. Lett. 107, 015701 (2011)]. Here, that framework is expanded to include general order parameters that distinguish different crystalline arrangements as target collective variables for enhanced sampling. The resulting free energy surface, being of quite high dimension, is nontrivial to reconstruct, and we discuss one particular strategy for performing the free energy analysis. The method is applied to the study of polymorphism in xenon crystals at high pressure and temperature using the Steinhardt order parameters without and with the supercell included in the set of collective variables. The expected fcc and bcc structures are obtained, and when the supercell parameters are included as collective variables, we also find several new structures, including fcc states with hcp stacking faults. We also apply the new method to the solid-liquid phase transition in copper at 1300 K using the same Steinhardt order parameters. Our method is able to melt and refreeze the system repeatedly, and the free energy profile can be obtained with high efficiency

  3. On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kristie Cooper; Gary Pickrell; Anbo Wang

    2005-11-01

    This report summarizes technical progress April-September 2005 on the Phase II program ''On-Line Self-Calibrating Single Crystal Sapphire Optical Sensor Instrumentation for Accurate and Reliable Coal Gasifier Temperature Measurement'', funded by the Federal Energy Technology Center of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. The objective of this program is to bring the sensor technology, which has already been demonstrated in the laboratory, to a level where the sensor can be deployed in the harsh industrial environments and will become commercially viable. Due to the difficulties described on the last report, field testing of the BPDI system has not continued to date. However, we have developed an alternative high temperature sensing solution, which is described in this report. The sensing system will be installed and tested at TECO's Polk Power Station. Following a site visit in June 2005, our efforts have been focused on preparing for that field test, including he design of the sensor mechanical packaging, sensor electronics, the data transfer module, and the necessary software codes to accommodate this application.. We are currently ready to start sensor fabrication.

  4. Effects on humans elicited by inhaling the fragrance of essential oils: sensory test, multi-channel thermometric study and forehead surface potential wave measurement on basil and peppermint.

    Science.gov (United States)

    Satoh, Tomoko; Sugawara, Yoshiaki

    2003-01-01

    The effects on humans inhaling the fragrance of essential oils were examined in terms of a sensory test, a multi-channel skin thermometer study and a portable forehead surface electroencephalographic (IBVA-EEG) measurement. The essential oils examined in this study were those of basil and peppermint, because our previous sensory test had indicated an opposite effect of these essential oils when mental work was undertaken; the inhalation of basil produced a more favorable impression after work than before work, whereas peppermint produced an unfavorable impression under these circumstances. For subjects administered basil or peppermint before and after mental work using an inhalator, a series of multi-channel skin thermometer studies and IBVA-EEG measurements were conducted. Using such paired odorants, our results showed that when compared between before and after mental work assigned to subjects: (1) the inhalation of basil, in which a favorable impression was predominant on the whole in terms of the sensory evaluation spectrum, was shown to be associated upward tendency in finger-tip skin temperature; (2) whereas these situations were opposite in the case of peppermint, in which the reversed (unfavorable) feature in sensory profiling was accompanied by a decrease in the magnitude of beta waves and a decrease in the finger-tip skin temperature both based on Welch's method, even at p < 0.01, implying a decreasing propensity of the aroused state and of the arousal response. The elucidation of such sensory and physiological endpoints of paired odorants would be of primary importance for human chemoreception science, because these are only rarely recorded during the same experiments, and this paradigm is highly informative about non-verbal responses to odorants.

  5. The steady-state and transient electron transport within bulk zinc-blende indium nitride: The impact of crystal temperature and doping concentration variations

    International Nuclear Information System (INIS)

    Siddiqua, Poppy; O'Leary, Stephen K.

    2016-01-01

    Within the framework of a semi-classical three-valley Monte Carlo electron transport simulation approach, we analyze the steady-state and transient aspects of the electron transport within bulk zinc-blende indium nitride, with a focus on the response to variations in the crystal temperature and the doping concentration. We find that while the electron transport associated with zinc-blende InN is highly sensitive to the crystal temperature, it is not very sensitive to the doping concentration selection. The device consequences of these results are then explored.

  6. Temperature and orientation dependence of the short-term strength characteristics, Young's modulus, and linear expansion coefficient of ZhS6F alloy single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Svetlov, I L; Sukhanov, N N; Krivko, A I; Roshchina, I N; Khatsinskaia, I M

    1987-01-01

    Experimental data are presented on the temperature dependence of the short- term strength characteristics, Young's modulus, and linear expansion coefficients of single crystals of a nickel alloy, ZhS6F, with crystallographic orientations along the 001, 111, 011, and 112 lines. It is found that the mechanical properties and Young's modulus of the alloy crystals exibit anisotropy in the temperature range 20-900 C. The linear thermal expansion coefficient is isotropic up to 900 C and equal to that of the equiaxed alloy. 10 references.

  7. Redox-active porous coordination polymer based on trinuclear pivalate: Temperature-dependent crystal rearrangement and redox-behavior

    Energy Technology Data Exchange (ETDEWEB)

    Lytvynenko, Anton S. [L.V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, Prospekt Nauki 31, Kiev 03028 (Ukraine); Kiskin, Mikhail A., E-mail: mkiskin@igic.ras.ru [N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Prospect 31, GSP-1, 119991 Moscow (Russian Federation); Dorofeeva, Victoria N.; Mishura, Andrey M.; Titov, Vladimir E.; Kolotilov, Sergey V. [L.V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, Prospekt Nauki 31, Kiev 03028 (Ukraine); Eremenko, Igor L.; Novotortsev, Vladimir M. [N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Prospect 31, GSP-1, 119991 Moscow (Russian Federation)

    2015-03-15

    Linking of trinuclear pivalate Fe{sub 2}NiO(Piv){sub 6} (Piv=O{sub 2}CC(CH{sub 3}){sub 3}) by 2,6-bis(4-pyridyl)-4-(1-naphthyl)pyridine (L) resulted in formation of 1D-porous coordination polymer Fe{sub 2}NiO(Piv){sub 6}(L)·Solv, which was characterized in two forms: DMSO solvate Fe{sub 2}NiO(Piv){sub 6}(L)(DMSO)·2.5DMSO (1) or water solvate Fe{sub 2}NiO(Piv){sub 6}(L)(H{sub 2}O) (2). X-ray structure of 1 was determined. Crystal lattice of 1 at 160 K contained open channels, filled by captured solvent, while temperature growth to 296 K led to the crystal lattice rearrangement and formation of closed voids. Redox-behavior of 2 was studied by cyclic voltammetry for a solid compound, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. The presence of pores in desolvated sample Fe{sub 2}NiO(Piv){sub 6}(L) was confirmed by the measurements of N{sub 2} and H{sub 2} adsorption at 77 K. Potential barriers of the different molecules diffusion through pores were estimated by the means of molecular mechanics. - Graphical abstract: Redox-behavior of 1D-porous coordination polymer Fe{sub 2}NiO(Piv){sub 6}(L)(H{sub 2}O) was studied by cyclic voltammetry in thin film, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. Potential barriers of different molecules diffusion through pores were estimated by the means of molecular mechanics. - Highlights: • Porous 1D coordination polymer was synthesized. • Temperature growth led to pores closing due to crystal lattice rearrangement. • Redox-activity of ligand preserved upon incorporation into coordination polymer. • Redox-properties of solid coordination polymer were studied in thin film. • Diffusion barriers were evaluated by molecular mechanics.

  8. Low temperature oxidative desulfurization with hierarchically mesoporous titaniumsilicate Ti-SBA-2 single crystals.

    Science.gov (United States)

    Shi, Chengxiang; Wang, Wenxuan; Liu, Ni; Xu, Xueyan; Wang, Danhong; Zhang, Minghui; Sun, Pingchuan; Chen, Tiehong

    2015-07-21

    Hierarchically porous Ti-SBA-2 with high framework Ti content (up to 5 wt%) was firstly synthesized by employing organic mesomorphous complexes of a cationic surfactant (CTAB) and an anionic polyelectrolyte (PAA) as templates. The material exhibited excellent performance in oxidative desulfurization of diesel fuel at low temperature (40 °C or 25 °C) due to the unique hierarchically porous structure and high framework Ti content.

  9. Growth of Ca, Zr co-doped BaTiO3 lead-free ferroelectric single crystal and its room-temperature piezoelectricity

    Directory of Open Access Journals (Sweden)

    Donglin Liu

    2017-09-01

    Full Text Available Lead-free Ca, Zr co-doped BaTiO3 (BCZT single crystal with a dimension up to 2mm×2mm×2mm was grown by a spontaneous nucleation technique using KF as the flux. The composition of the studied single crystal was defined to be Ba0.798Ca0.202Zr0.006Ti0.994O3, corresponding to a tetragonal phase at room temperature. The oriented single crystal exhibited a quasi-static piezoelectric constant of approximately 232 pC/N. The effective piezoelectric coefficient d33* of the single domain crystal obtained under a unipolar electric field of 35 kV/cm was 179 pm/V. Rayleigh analysis was used to identify the intrinsic and extrinsic contributions to the room-temperature piezoelectricity of BCZT single crystal. The extrinsic contribution was estimated up to 40% due to the irreversible domain wall movement. Furthermore a sixth-order polynomial of Landau expansion was employed to analyze the intrinsic contribution to piezoelectricity of BCZT single crystal. The large energy barriers inhibited polarization rotations, leading to the relatively low piezoelectricity.

  10. Low temperature phase transition and crystal structure of CsMgPO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Orlova, Maria, E-mail: maria.p.orlova@gmail.com [Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52, Innsbruck 6020 (Austria); Khainakov, Sergey [Departamento de Química Física y Analítica, Universidad de Oviedo—CINN, 33006 Oviedo (Spain); Servicios Científico Técnicos, Universidad de Oviedo, 33006 Oviedo (Spain); Michailov, Dmitriy [Department of Chemistry, University of Nizhny Novgorod, 23 Gagarin av., Nizhny Novgorod 603950 (Russian Federation); Perfler, Lukas [Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52, Innsbruck 6020 (Austria); Langes, Christoph [Institute of Pharmacy, University of Innsbruck, Innrain 52, Innsbruck 6020 (Austria); Kahlenberg, Volker [Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52, Innsbruck 6020 (Austria); Orlova, Albina [Department of Chemistry, University of Nizhny Novgorod, 23 Gagarin av., Nizhny Novgorod 603950 (Russian Federation)

    2015-01-15

    CsMgPO{sub 4} doped with radioisotopes is a promising compound for usage as a radioactive medical source. However, a low temperature phase transition at temperatures close to ambient conditions (∼−40 °C) was observed. Information about such kind of structural changes is important in order to understand whether it can cause any problem for medical use of this compound. The phase transition has been investigated in detail using synchrotron powder diffraction, Raman spectroscopy and DFT calculations. The structure undergoes a transformation from an orthorhombic modification, space group Pnma (RT phase) to a monoclinic polymorph, space group P2{sub 1}/n (LT phase). New LT modification adopts similar to RT but slightly distorted unit cell: a=9.58199(2) Å, b=8.95501(1) Å, c=5.50344(2) Å, β=90.68583(1)°, V=472.198(3) Å{sup 3}. CsMgPO{sub 4} belongs to the group of framework compounds and is made up of strictly alternating MgO{sub 4}- and PO{sub 4}-tetrahedra sharing vertices. The cesium counter cations are located in the resulting channel-like cavities. Upon the transformation a combined tilting of the tetrahedra is observed. A comparison with other phase transitions in ABW-type framework compounds is given. - Graphical abstract: Structural behavior of β-tridymite-type phosphate CsMgPO{sub 4}, considered as potential chemical form for radioactive Cs-source has been studied at near ambient temperatures. A phase transition at (∼−40 °C) has been found and investigated. It has been established that the known orthorhombic RT modification, space group Pnma, adopts a monoclinic cell with space group P2{sub 1}/n at low temperatures. In this paper, we present results of structural analysis of changes accompanying this phase transition and discuss its possible impact on the application properties. - Highlights: • β-Tridymite type phosphate CsMgPO{sub 4} undergoes so called translationengleiche phase transition of index 2 at −40 °C. • The structure

  11. Growth of a New Ternary BON Crystal on Si(100) by Plasma-Assisted MOCVD and Study on the Effects of Fed Gas and Growth Temperature

    Science.gov (United States)

    Chen, G. C.; Lee, S.-B.; Boo, J.-H.

    A new ternary BOxNy crystal was grown on Si(100) substrate at 500°C by low-frequency (100 kHz) radio-frequency (rf) derived plasma-assisted MOCVD with an organoborate precursor. The as-grown deposits were characterized by SEM, TED, XPS, XRD, AFM and FT-IR. The experimental results showed that BOxNy crystal was apt to be formed at N-rich atmosphere and high temperature. The decrease of hydrogen flux in fed gases was of benefit to form BON crystal structure. The crystal structure of BOxNy was as similar to that of H3BO3 in this study.

  12. The use of quasi-isothermal modulated temperature differential scanning calorimetry for the characterization of slow crystallization processes in lipid-based solid self-emulsifying systems.

    Science.gov (United States)

    Otun, Sarah O; Meehan, Elizabeth; Qi, Sheng; Craig, Duncan Q M

    2015-04-01

    Slow or incomplete crystallization may be a significant manufacturing issue for solid lipid-based dosage forms, yet little information is available on this phenomenon. In this investigation we suggest a novel means by which slow solidification may be monitored in Gelucire 44/14 using quasi-isothermal modulated temperature DSC (QiMTDSC). Conventional linear heating and cooling DSC methods were employed, along with hot stage microscopy (HSM), for basic thermal profiling of Gelucire 44/14. QiMTDSC experiments were performed on cooling from the melt, using a range of incremental decreases in temperature and isothermal measurement periods. DSC and HSM highlighted the main (primary) crystallization transition; solid fat content analysis and kinetic analysis were used to profile the solidification process. The heat capacity profile from QiMTDSC indicated that after an initial energetic primary crystallisation, the lipid underwent a slower period of crystallization which continued to manifest at much lower temperatures than indicated by standard DSC. We present evidence that Gelucire 44/14 undergoes an initial crystallization followed by a secondary, slower process. QIMTDSC appears to be a promising tool in the investigation of this secondary crystallization process.

  13. Room temperature single-crystal diffuse scattering and ab initio lattice dynamics in CaTiSiO5.

    Science.gov (United States)

    Gutmann, M J; Refson, K; Zimmermann, M V; Swainson, I P; Dabkowski, A; Dabkowska, H

    2013-08-07

    Single-crystal diffuse scattering data have been collected at room temperature on synthetic titanite using both neutrons and high-energy x-rays. A simple ball-and-springs model reproduces the observed diffuse scattering well, confirming its origin to be primarily due to thermal motion of the atoms. Ab initio phonons are calculated using density-functional perturbation theory and are shown to reproduce the experimental diffuse scattering. The observed diffuse x-ray and neutron scattering patterns are consistent with a summation of mode frequencies and displacement eigenvectors associated with the entire phonon spectrum, rather than with a simple, short-range static displacement. A band gap is observed between 600 and 700 cm(-1) with only two modes crossing this region, both associated with antiferroelectric Ti-O motion along a. One of these modes (of Bu symmetry), displays a large LO-TO mode-splitting (562-701.4 cm(-1)) and has a dominant component coming from Ti-O bond-stretching and, thus, the mode-splitting is related to the polarizability of the Ti-O bonds along the chain direction. Similar mode-splitting is observed in piezo- and ferroelectric materials. The calculated phonon dispersion model may be of use to others in future to understand the phase transition at higher temperatures, as well as in the interpretation of measured phonon dispersion curves.

  14. Proton spin-lattice relaxation in a liquid crystal-Aerosil complex above the bulk isotropization temperature

    Energy Technology Data Exchange (ETDEWEB)

    Anoardo, E.; Grinberg, F.; Vilfan, M.; Kimmich, R

    2004-02-16

    We present a study of the molecular dynamics in an octylcyanobiphenyl (8CB)-Aerosil complex above the bulk isotropization temperature. Using proton nuclear magnetic relaxation experiments in the laboratory frame (T{sub 1}{sup -1}) and in the rotating-frame (T{sub 1{rho}}{sup -1}), we found a notable increase of the relaxation rates in the kHz frequency range as compared to the bulk 8CB liquid crystal at the same temperature. The field-cycling technique was used for the laboratory frame experiments while a conventional apparatus was used for the rotating frame method. The observed behavior is analyzed with the aid of Monte Carlo simulations on the basis of a two-phase fast-exchange model distinguishing surface-ordered and bulk phases. Two processes affecting the low frequency relaxation could be identified: reorientation mediated by translational displacements, accounting for molecular reorientations, and exchange losses of molecules from the surface to the bulk.

  15. P-V-T properties of a polymer liquid crystal subjected to pre-drawing at several temperatures

    International Nuclear Information System (INIS)

    Broza, Georg; Castano, Victor M.; Martinez-Barrera, Gonzalo; Menard, Kevin P.; Simoes, Carla

    2005-01-01

    We have studied the copolymer of poly(ethylene terephthalate) (PET) with 0.6mole fraction of p-hydroxybenzoic acid (PHB). It is a longitudinal polymer liquid crystal (PLC). A number of otherwise identical samples were subjected to drawing to achieve in turn 20%, 40%, 60%, 80% and 100% increase in length. The drawing was performed isothermally at 60, 100 and 140 deg. C. Pressure-volume-temperature (P-V-T) results have been obtained for pressures up to 200Jcm -3 and temperatures up to 150 deg. C or so. Parameters of the Hartmann equation of state have been evaluated. Drawing first results in an increase in specific (and also free) volume, then in a decrease caused by increased orientation of the PLC, and finally in an apparent increase caused by the appearance of voids. The tensile modulus E has been determined for all pre-drawn samples. It reflects the volumetric changes a rebours: the initial increase in specific volume results in lower E values, orientation in E increase, and void formation in a second decrease

  16. Self-Assembly of Colloidal Photonic Crystals of PS@PNIPAM Nanoparticles and Temperature-Responsive Tunable Fluorescence.

    Science.gov (United States)

    Yuan, Shuai; Ge, Fengyan; Yang, Xue; Guang, Shanyi

    2016-11-01

    A strategy for significantly enhancing fluorescence is developed based on the coupling of optical properties of colloidal photonic crystals (CPCs) with responsive microgel. In this paper, thermoresponsive microgel PNIPAM was employed for the fabrication of core-shell structure. The core-shell PS@PNIPAM nanoparticles (NPs) are then assembled to CPCs by a vertical deposition method. Subsequently, the novel functional material (RhB/CPCs) can be prepared by depositing fluorescent dye molecules (RhB) on the top of PS@PNIPAM CPCs. We obtained an increase in the fluorescent intensity up to 15-fold and 22-fold compared with RhB on the glass slid and the uneven film. Due to the unique responsive shrinking properties of PNIPAM shell, the amplifying fluorescence behavior of CPCs can be well tuned by varying the temperature. In contrast to RhB on the glass slid, a 15-fold and 12-fold fluorescence enhancement can be observed when the temperature of RhB/CPCs was 20 °C and 50 °C, respectively. The mechanism on enhancement fluorescence of tunable CPCs can be achieved by measurements of thermoresponsive properties. The results indicate that the responsive fluorescence-amplifying method based on CPCs made with responsive core-shell NPs has a potential application for the development of efficient fluorescence sensors.

  17. The Naso-labial and lateral forehead flaps as a single stage: A case report and review of literature

    Directory of Open Access Journals (Sweden)

    Adigun I

    2008-01-01

    Full Text Available We present here the case of a patient with a major traumatic nasal loses who had a near-total nasal reconstruction as a single-stage procedure. A 35 year-old civil servant who was involved in a road traffic injury about two years before presentation. He sustained extensive and multiple facial injuries with complete loss of nasal cover and lining. Reconstruction was performed by using superiorly based, bilateral, nasolabial flaps to line the floor and the nasal septum, and a paramedian forehead flap for skin cover. The patient did well postoperatively and was discharged home on the 7 th postoperative day. If the principles concerning cover, support, and lining are adhered to, excellent functional and aesthetic results can be achieved as we have obtained in our patient.

  18. Utilidad del colgajo frontal en la reconstrucción nasal Usefulness of the forehead flap in the nasal reconstruction

    Directory of Open Access Journals (Sweden)

    Julio César Gálvez Chávez

    2009-03-01

    Full Text Available INTRODUCCIÓN. La nariz constituye el centro estético de la cara y cualquier deformidad en ella afecta de modo importante a la armonía facial. Este estudio tuvo como objetivo caracterizar las experiencias en reconstrucción nasal con colgajo frontal en pacientes con defectos anatómicos de la nariz, como consecuencia fundamentalmente de una cirugía oncológica. MÉTODOS. Se realizó un estudio descriptivo, prospectivo, para caracterizar la experiencia de la reconstrucción nasal con colgajo frontal en pacientes con defectos nasales, atendidos en el Hospital «Hermanos Ameijeiras» y en el Instituto Nacional de Oncología y Radiobiología, entre junio de 1999 y mayo de 2007. RESULTADOS. Destacó que el motivo más frecuente de reconstrucción fue la lesión neoplásica, con igual número de pacientes afectados por carcinoma basocelular y epidermoide. El ala nasal fue la zona más afectada y se presentó recidiva tumoral en 5 pacientes. En todos los casos se pudo crear una cubierta externa al defecto y el diseño oblicuo fue el más utilizado. Se reconstruyó la cubierta interna nasal fundamentalmente con injerto de piel total y el soporte nasal, mayormente con injertos cartilaginosos de la concha auricular. Todos los colgajos frontales se mantuvieron vitales después de su desconexión en el segundo tiempo quirúrgico. El cierre directo de la zona donante fue el más utilizado y en algunos casos se logró con la utilización de expansión tisular. Se realizó un tercer tiempo de remodelación en los pacientes que lo necesitaron. Las complicaciones no afectaron al resultado final de la reconstrucción. CONCLUSIONES. Se demostró la utilidad y vigencia del colgajo frontal en la reconstrucción nasal.ABSTRACT INTRODUCTION. The nose is the aesthetic center of the face and any deformity in it significantly affects facial harmony. This study was aimed at characterizing the experiences in nasal reconstruction with forehead flap in patients with

  19. Middle Cerebral Artery, Ophthalmic Artery, and Multibranch Retinal Vessel Occlusion After Cosmetic Autologous Fat Transfer to Forehead.

    Science.gov (United States)

    Roshandel, Danial; Soheilian, Masoud; Pakravan, Mohammad; Aghayan, Sara; Peyman, Gholam A

    2015-05-01

    A 65-year-old woman with left hemiparesis and sudden loss of visual acuity in her right eye presented a few hours after cosmetic injection of autologous fat to her forehead. Right eye visual acuity was no light perception. Funduscopy revealed widespread retinal whitening and multibranch retinal vessel occlusion. Fluorescein angiography showed markedly delayed choroidal and retinal filling together with occlusion of multiple branches of retinal arteries and veins. On magnetic resonance imaging of the brain, multiple lesions compatible with recent infarction were detected. The authors diagnosed multibranch retinal artery and vein occlusion in the right ophthalmic and middle cerebral arteries due to fat emboli. This case emphasizes the need to reevaluate the safety of such aesthetic procedures, particularly in the facial zone to prevent devastating complications. Copyright 2015, SLACK Incorporated.

  20. Size and temperature dependent stability and phase transformation in single-crystal zirconium nanowire

    International Nuclear Information System (INIS)

    Sutrakar, Vijay Kumar; Roy Mahapatra, D.

    2011-01-01

    A novel size dependent FCC (face-centered-cubic) → HCP (hexagonally-closed-pack) phase transformation and stability of an initial FCC zirconium nanowire are studied. FCC zirconium nanowires with cross-sectional dimensions 20 Å, in which surface stresses are not enough to drive the phase transformation, show meta-stability. In such a case, an external kinetic energy in the form of thermal heating is required to overcome the energy barrier and achieve FCC → HCP phase transformation. The FCC-HCP transition pathway is also studied using Nudged Elastic Band (NEB) method, to further confirm the size dependent stability/metastability of Zr nanowires. We also show size dependent critical temperature, which is required for complete phase transformation of a metastable-FCC nanowire.

  1. Lower-temperature crystallization of CoFeB in MgO magnetic tunnel junctions by using Ti capping layer

    International Nuclear Information System (INIS)

    Ibusuki, Takahiro; Miyajima, Toyoo; Umehara, Shinjiro; Eguchi, Shin; Sato, Masashige

    2009-01-01

    Effects of capping materials on magnetoresistance (MR) properties of MgO magnetic tunnel junctions (MTJs) with a CoFeB free layer were investigated. MR ratios of samples with various capping materials showed a difference in annealing temperature dependence. MTJ with a Ti capping layer annealed at 270 deg. C showed a MR ratio 1.4 times greater than that with a conventional Ta or Ru capping layer. Secondary ion mass spectroscopy and high-resolution transmission electron microscopy images revealed that crystallization of CoFeB was remarkably affected by adjacent materials and the Ti capping layer adjoining CoFeB acted as a boron-absorption layer. These results suggest that the crystallization process can be controlled by choosing proper capping materials. Ti is one of the effective materials that accelerate the crystallization of CoFeB layers at lower annealing temperature

  2. Study of plastic deformation peculiarities in CdS single crystals within the temperature range of 25 to 300 deg C

    International Nuclear Information System (INIS)

    Bulatova, T.M.

    1990-01-01

    By the method of stress relaxation dependences of platic deformation rate on effective strain in CdS monocrystals for the temperatures of 25-300 deg C both in the darkness and in the light are obtained. In the range of the temperatures up to 150 deg C deformation activation energy is determined, which correlates with the value of point defect diffusion activation energy in the crystal. Anomalous temperature dependence of plastic deformation rate, i.e. its decrease with the temperature increase in the range of 150-300 deg C is detected

  3. Temperature dependent tunneling study of CaFe{sub 1.96}Ni{sub 0.04}As{sub 2} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Anirban, E-mail: adatta@iitk.ac.in; Gupta, Anjan K. [Department of Physics, IIT Kanpur, Kanpur-208 016 (India); Thamizhavel, A. [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400 005 (India)

    2014-04-24

    We report on temperature dependent scanning tunneling microscopy and spectroscopy studies on CaFe{sub 1.96}Ni{sub 0.04}As{sub 2} single crystals in 5.4 – 19.7 K temperature range across the normal metal - superconductor transition temperature, T{sub C} = 14K. The in-situ cleaved crystals show reasonably flat surface with signatures of atomic resolution. The tunnel spectra show significant spatial inhomogeneity below T{sub C}, which reduces significantly as the temperature goes above the T{sub C}. We discuss these results in terms of an inhomogeneous electronic phase that may exist due to the vicinity of this composition to the quantum critical point.

  4. Measurement of Gamma-ray Energy Spectrum According to Temperature Variation Using a Fiber-Optic Radiation Sensor Based on YSO:Ce Crystal

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, H.; Yoo, W. J.; Shin, S. H.; Jang, J. S.; Kim, J. S.; Kwon, G.; Lee, D. E.; Jang, K. W.; Lee, B. [BK21 Plus Research Institute of Biomedical Engineering, Konkuk University, Chungju (Korea, Republic of)

    2015-05-15

    As an alternative to conventional radiation detectors, various fiber-optic radiation sensors (FORSs) have been investigated for gamma-ray monitoring because of their various desirable advantages, such as their small sensing volume, substantial flexibility, remote operation, ability to make real-time measurement, and immunity to high electromagnetic interference. In general, the basic principle of a radiation detection using scintillators is to measure the scintillating light signals generated from the interactions between the scintillators and the radiations. To measure gamma-ray, the inorganic scintillators used in the FORS should have some properties, such as high atomic material, high light yields, fast decay time, high density, and high stopping power. For these reasons, a cerium-doped lutetium yttrium orthosilicate (LYSO:Ce) crystal has been introduced as a promising scintillator in various radiation sensor applications. According to the recent studies, however, LYSO:Ce crystal is impossible to be applied in high-temperature conditions because it serves the fluctuations of its light yields with the temperature variation (i.e., thermosluminescence). In this study, to obtain gamma-ray energy spectra by measuring scintillating light signals emitted from the scintillators in high-temperature conditions, we first fabricated an FORS system using various inorganic scintillator crystals and then evaluated the light yields of each inorganic scintillator. As a promising scintillator for use in high-temperature conditions, a cerium-doped yttrium orthosilicate (YSO:Ce) crystal was selected and evaluated its thermal property according to the elevated temperature up to 300 .deg. C. We fabricated an FORS using inorganic scintillator and an optical fiber bundle. To select an adequate scintillator to apply in high-temperature conditions, the gamma-ray energy spectra were obtained by using four kinds of inorganic scintillators. From the experimental results, we selected YSO

  5. A Crystallization-Temperature Profile Through Paleo-Oceanic Crust (Wadi Gideah Transect, Oman Ophiolite): Application of the REE-in-Plagioclase-Clinopyroxene Partitioning Thermometer

    Science.gov (United States)

    Mueller, S.; Hasenclever, J.; Garbe-Schönberg, D.; Koepke, J.; Hoernle, K.

    2017-12-01

    The accretion mechanisms forming oceanic crust at fast spreading ridges are still under controversial discussion. Thermal, petrological, and geochemical observations predict different end-member models, i.e., the gabbro glacier and the sheeted sill model. They all bear implications for heat transport, temperature distribution, mode of crystallization and hydrothermal heat removal over crustal depth. In a typical MOR setting, temperature is the key factor driving partitioning of incompatible elements during crystallization. LA-ICP-MS data for co-genetic plagioclase and clinopyroxene in gabbros along a transect through the plutonic section of paleo-oceanic crust (Wadi Gideah Transect, Oman ophiolite) reveal that REE partitioning coefficients are relatively constant in the layered gabbro section but increase for the overlying foliated gabbros, with an enhanced offset towards HREEs. Along with a systematic enrichment of REE's with crustal height, these trends are consistent with a system dominated by in-situ crystallization for the lower gabbros and a change in crystallization mode for the upper gabbros. Sun and Liang (2017) used experimental REE partitioning data for calibrating a new REE-in-plagioclase-clinopyroxene thermometer that we used here for establishing the first crystallization-temperature depth profile through oceanic crust that facilitates a direct comparison with thermal models of crustal accretion. Our results indicate crystallization temperatures of about 1220±8°C for the layered gabbros and lower temperatures of 1175±8°C for the foliated gabbros and a thermal minimum above the layered-to-foliated gabbro transition. Our findings are consistent with a hybrid accretion model for the oceanic crust. The thermal minimum is assumed to represent a zone where the descending crystal mushes originating from the axial melt lens meet with mushes that have crystallized in situ. These results can be used to verify and test thermal models (e.g., Maclennan et al

  6. In silico prediction of nematic transition temperature for liquid crystals using quantitative structure-property relationship approaches.

    Science.gov (United States)

    Fatemi, Mohammad Hossein; Ghorbanzad'e, Mehdi

    2009-11-01

    Quantitative structure-property relationship models for the prediction of the nematic transition temperature (T (N)) were developed by using multilinear regression analysis and a feedforward artificial neural network (ANN). A collection of 42 thermotropic liquid crystals was chosen as the data set. The data set was divided into three sets: for training, and an internal and external test set. Training and internal test sets were used for ANN model development, and the external test set was used for evaluation of the predictive power of the model. In order to build the models, a set of six descriptors were selected by the best multilinear regression procedure of the CODESSA program. These descriptors were: atomic charge weighted partial negatively charged surface area, relative negative charged surface area, polarity parameter/square distance, minimum most negative atomic partial charge, molecular volume, and the A component of moment of inertia, which encode geometrical and electronic characteristics of molecules. These descriptors were used as inputs to ANN. The optimized ANN model had 6:6:1 topology. The standard errors in the calculation of T (N) for the training, internal, and external test sets using the ANN model were 1.012, 4.910, and 4.070, respectively. To further evaluate the ANN model, a crossvalidation test was performed, which produced the statistic Q (2) = 0.9796 and standard deviation of 2.67 based on predicted residual sum of square. Also, the diversity test was performed to ensure the model's stability and prove its predictive capability. The obtained results reveal the suitability of ANN for the prediction of T (N) for liquid crystals using molecular structural descriptors.

  7. Time temperature transformation diagram for secondary crystal products of Co-based Co-Fe-B-Si-Nb-Mn soft magnetic nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    DeGeorge, V., E-mail: vdegeorge@cmu.edu; Zoghlin, E.; Keylin, V.; McHenry, M. [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

    2015-05-07

    Secondary crystallization is the subject of much investigation in magnetic amorphous and nanocomposites (MANCs) as it limits the long term and thermal stability of their operation in device applications, including power electronics, sensors, and electric motors. Secondary crystal products [Blazquez et al., Philos. Mag. Lett. 82(7), 409–417 (2002); Ohodnicki et al., Phys. Rev. B 78, 144414 (2008); Willard et al., Metall. Mater. Trans. A 38, 725 (2007)], nanostructure and crystallization kinetics [Hsiao et al., IEEE Trans. Magn. 38(5), 3039 (2002); McHenry et al., Scr. Mater. 48(7), 881 (2003)], and onset temperatures and activation energies [Ohodnicki et al., Acta. Mater. 57, 87 (2009); Long et al., J. Appl. Phys. 101, 09N114 (2007)] at constant heating have been reported for similar alloys. However, a time-temperature-transformation (TTT) diagram for isothermal crystallization, more typical of application environments, has not been reported in literature. Here, a TTT diagram for the Co based, Co-Fe-Si-Nb-B-Mn MANC system is presented, along with a method for determining such. The method accounts for the presence of primary crystal phases and yields crystal fraction of secondary phase(s) by using a novel four stage heating profile. The diagram, affirmed by Kissinger activation energy analysis, reports thermal stability of the MANC for millennia at conventional device operating temperatures, and stability limits less than a minute at elevated temperatures. Both extremes are necessary to be able to avoid secondary crystalline products and establish operating limits for this mechanically attractive, high induction soft magnetic nanocomposite.

  8. Micromechanical properties of single crystals and polycrystals of pure α-titanium: anisotropy of microhardness, size effect, effect of the temperature (77-300 K)

    Science.gov (United States)

    Lubenets, S. V.; Rusakova, A. V.; Fomenko, L. S.; Moskalenko, V. A.

    2018-01-01

    The anisotropy of microhardness of pure α-Ti single crystals, indentation size effect in single-crystal, course grained (CG) pure and nanocrystalline (NC) VT1-0 titanium, as well as the temperature dependences of the microhardness of single-crystal and CG Ti in the temperature range 77-300 K were studied. The minimum value of hardness was obtained when indenting into the basal plane (0001). The indentation size effect (ISE) was clearly observed in the indentation of soft high-purity single-crystal iodide titanium while it was the least pronounced in a sample of nanocrystalline VT1-0 titanium. It has been demonstrated that the ISE can be described within the model of geometrically necessary dislocations (GND), which follows from the theory of strain gradient plasticity. The true hardness and others parameters of the GND model were determined for all materials. The temperature dependence of the microhardness is in agreement with the idea of the governing role of Peierls relief in the dislocation thermally-activated plastic deformation of pure titanium as has been earlier established and justified in macroscopic tensile investigations at low temperatures. The activation energy and activation volume of dislocation motion in the strained region under the indenter were estimated.

  9. Temperature- and moisture-dependent phase changes in crystal forms of barbituric acid

    International Nuclear Information System (INIS)

    Zencirci, Neslihan; Gstrein, Elisabeth; Langes, Christoph; Griesser, Ulrich J.

    2009-01-01

    The dihydrate of barbituric acid (BAc) and its dehydration product, form II were investigated by means of moisture sorption analysis, hot-stage microscopy, differential scanning calorimetry, thermogravimetry, solution calorimetry, IR- and Raman-spectroscopy as well as powder X-ray diffraction. The dihydrate desolvates already at and below 50% relative humidity (RH) at 25 deg. C whereas form II is stable up to 80% RH, where it transforms back to the dihydrate. The thermal dehydration of barbituric acid dihydrate (BAc-H2) is a single step, nucleation controlled process. The peritectic reaction of the hydrate was measured at 77 deg. C and a transformation enthalpy of Δ trs H H2-II = 17.3 kJ mol -1 was calculated for the interconversion between the hydrate and form II. An almost identical value of 17.0 kJ mol -1 was obtained from solution calorimetry in water as solvent (Δ sol H H2 = 41.5, Δ sol H II = 24.5 kJ mol -1 ). Additionally a high-temperature form (HT-form) of BAc, which is enantiotropically related to form II and unstable at ambient conditions has been characterized. Furthermore, we observed that grinding of BAc with potassium bromide (KBr) induces a tautomeric change. Therefore, IR-spectra recorded with KBr-discs usually display a mixture of tautomers, whereas the IR-spectra of the pure trioxo-form of BAc are obtained if alternative preparation techniques are used

  10. Effects of B{sub 2}O{sub 3} content and sintering temperature on crystallization and microstructure of CBS glass–ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Li, Pengyang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Wang, Shubin, E-mail: shubinwang@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials and Engneering, Beihang University, Beijing 100191 (China); Liu, Jianggao; Feng, Mengjie; Yang, Xinwang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2015-11-30

    Graphical abstract: (a) TEM photogram of CG3 sintered at 800 °C, crystals are obvious; (b) the XRD patterns of CG3 glass samples sintered at various temperatures; (c) SEM photogram of CG3 sintered at 800 °C; (d) Kissinger, Augis–Bennett and Ozawa kinetics plots of CG3 glass samples. - Highlights: • Combining sol–gel method with direct sintering method to reduce the temperature of coatings formation. • Characterizing CaO–SiO{sub 2}–B{sub 2}O{sub 3} glass–ceramic coatings on porous substrates. • Surface crystallization of CBS glass–ceramic coatings: nucleation and kinetics. • Activation energies for crystal growth in CBS glass–ceramics with different contents of B{sub 2}O{sub 3}. - Abstract: Borosilicate glass–ceramics precursors with varying compositional ratios in the CaO–SiO{sub 2}–B{sub 2}O{sub 3} (CBS) system were synthesized by sol–gel method. The precursors were calcined at 1200 °C for 2 h to form glass powders. The glass–ceramics were prepared by overlaying glass slurries on the substrates before sintering at different temperatures. The as-prepared glasses and glass–ceramics were characterized by differential scanning calorimetry and X-ray diffraction. The crystallization activation energies (E{sub c}) were calculated using the Kissinger method from DSC results. The morphology and crystallization behavior of the glass–ceramics were monitored by scanning electron microscopy. Both glass transition and crystallization temperatures decreased, however, the metastable zone increased. The E{sub c} values of CBS glasses and glass–ceramics were 254.1, 173.2 and 164.4 kJ/mol with increasing B{sub 2}O{sub 3} content, whereas that of the calcined G3 glass was 104.9 kJ/mol. Finally, the coatings were prepared at a low temperature (700 °C). The crystals that grew on the surface of multilayer coatings demonstrated heterogeneous surface nucleation and crystallization after heat-treatment from 700 °C to 850 °C for 4 h.

  11. Temperature- and moisture-dependent phase changes in crystal forms of barbituric acid

    Energy Technology Data Exchange (ETDEWEB)

    Zencirci, Neslihan; Gstrein, Elisabeth; Langes, Christoph [Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Innsbruck, Innrain 52, 6020 Innsbruck (Austria); Griesser, Ulrich J. [Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Innsbruck, Innrain 52, 6020 Innsbruck (Austria)], E-mail: ulrich.griesser@uibk.ac.at

    2009-03-10

    The dihydrate of barbituric acid (BAc) and its dehydration product, form II were investigated by means of moisture sorption analysis, hot-stage microscopy, differential scanning calorimetry, thermogravimetry, solution calorimetry, IR- and Raman-spectroscopy as well as powder X-ray diffraction. The dihydrate desolvates already at and below 50% relative humidity (RH) at 25 deg. C whereas form II is stable up to 80% RH, where it transforms back to the dihydrate. The thermal dehydration of barbituric acid dihydrate (BAc-H2) is a single step, nucleation controlled process. The peritectic reaction of the hydrate was measured at 77 deg. C and a transformation enthalpy of {delta}{sub trs}H{sub H2-II} = 17.3 kJ mol{sup -1} was calculated for the interconversion between the hydrate and form II. An almost identical value of 17.0 kJ mol{sup -1} was obtained from solution calorimetry in water as solvent ({delta}{sub sol}H{sub H2} = 41.5, {delta}{sub sol}H{sub II} = 24.5 kJ mol{sup -1}). Additionally a high-temperature form (HT-form) of BAc, which is enantiotropically related to form II and unstable at ambient conditions has been characterized. Furthermore, we observed that grinding of BAc with potassium bromide (KBr) induces a tautomeric change. Therefore, IR-spectra recorded with KBr-discs usually display a mixture of tautomers, whereas the IR-spectra of the pure trioxo-form of BAc are obtained if alternative preparation techniques are used.

  12. Adsorption Device Based on a Langatate Crystal Microbalance for High Temperature High Pressure Gas Adsorption in Zeolite H-ZSM-5.

    Science.gov (United States)

    Ding, Wenjin; Baracchini, Giulia; Klumpp, Michael; Schwieger, Wilhelm; Dittmeyer, Roland

    2016-08-25

    We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate crystal microbalance, LCM) and its use for gas adsorption measurements in zeolite H-ZSM-5. Prior to the adsorption measurements, zeolite H-ZSM-5 crystals were synthesized on the gold electrode in the center of the LCM, without covering the connection points of the gold electrodes to the oscillator, by the steam-assisted crystallization (SAC) method, so that the zeolite crystals remain attached to the oscillating microbalance while keeping good electroconductivity of the LCM during the adsorption measurements. Compared to a conventional quartz crystal microbalance (QCM) which is limited to temperatures below 80 °C, the LCM can realize the adsorption measurements in principle at temperatures as high as 200-300 °C (i.e., at or close to the reaction temperature of the target application of one-stage DME synthesis from the synthesis gas), owing to the absence of crystalline-phase transitions up to its melting point (1,470 °C). The system was applied to investigate the adsorption of CO2, H2O, methanol and dimethyl ether (DME), each in the gas phase, on zeolite H-ZSM-5 in the temperature and pressure range of 50-150 °C and 0-18 bar, respectively. The results showed that the adsorption isotherms of these gases in H-ZSM-5 can be well fitted by Langmuir-type adsorption isotherms. Furthermore, the determined adsorption parameters, i.e., adsorption capacities, adsorption enthalpies, and adsorption entropies, compare well to literature data. In this work, the results for CO2 are shown as an example.

  13. Inducing phase decomposition and superconductivity of Bi2Sr2CaCu2Oy single crystals treated in sulphur atmosphere at low temperature

    International Nuclear Information System (INIS)

    Chen, Q.W.; China Univ. of Science and Technology, Hefei, AH; Wu, W.B.; Qian, Y.T.; China Univ. of Science and Technology, Hefei, AH; Wang, L.B.; Li, F.Q.; Zhou, G.E.; Chen, Z.Y.; Zhang, Y.H.

    1995-01-01

    As it has been pointed out, phase decomposition which may be hard to be detected in a polycrystalline system and is likely to correlate with changes in both oxygen content and microstructure, has been observed frequently in annealed single crystals especially at higher temperatures (> 500 C). This is still an open question to some degree because the mechanism of phase decomposition is very complex and is dominated by the composition of the Bi-2212 phase, the condition of heat treatment, and the atmosphere. Hence, inducing oxygen loss at low temperature to avoid the evaporation of Bi atoms and other undetected structure changes which would occur at higher temperature annealing undoubtedly provides important information about the relationship between oxygen loss and phase decomposition, as well as the relationship between oxygen content and superconductivity. In this note, we report on the results of treatments of Bi 2 Sr 2 CaCu 2 O y single crystals in sulphur atmosphere at 160 C. (orig.)

  14. Small-Scale Gravity Waves in ER-2 MMS/MTP Wind and Temperature Measurements during CRYSTAL-FACE

    Science.gov (United States)

    Wang, L.; Alexander, M. J.; Bui, T. P.; Mahoney, M. J.

    2006-01-01

    Lower stratospheric wind and temperature measurements made from NASA's high-altitude ER-2 research aircraft during the CRYSTAL-FACE campaign in July 2002 were analyzed to retrieve information on small scale gravity waves (GWs) at the aircraft's flight level (typically approximately 20 km altitude). For a given flight segment, the S-transform (a Gaussian wavelet transform) was used to search for and identify small horizontal scale GW events, and to estimate their apparent horizontal wavelengths. The horizontal propagation directions of the events were determined using the Stokes parameter method combined with the cross S-transform analysis. The vertical temperature gradient was used to determine the vertical wavelengths of the events. GW momentum fluxes were calculated from the cross S-transform. Other wave parameters such as intrinsic frequencies were calculated using the GW dispersion relation. More than 100GW events were identified. They were generally high frequency waves with vertical wavelength of approximately 5 km and horizontal wavelength generally shorter than 20 km. Their intrinsic propagation directions were predominantly toward the east, whereas their ground-based propagation directions were primarily toward the west. Among the events, approximately 20% of them had very short horizontal wavelength, very high intrinsic frequency, and relatively small momentum fluxes, and thus they were likely trapped in the lower stratosphere. Using the estimated GW parameters and the background winds and stabilities from the NCAR/NCEP reanalysis data, we were able to trace the sources of the events using a simple reverse ray-tracing. More than 70% of the events were traced back to convective sources in the troposphere, and the sources were generally located upstream of the locations of the events observed at the aircraft level. Finally, a probability density function of the reversible cooling rate due to GWs was obtained in this study, which may be useful for cirrus

  15. Investigation on structural distortions in NBCsub(x)-single crystals by means of temperature dependent channeling measurements

    International Nuclear Information System (INIS)

    Kaufmann, R.

    1981-08-01

    Investigations using channeling-experiments were performed on the magnitude of the static displacements of the niobium and the carbon atoms around C-vacancies in NbCsub(x)-single crystals (x = 0.82-0.98). Rutherford backscattering with 2 MeV He + -particles and the 12 C(d,p) 13 C-nuclear reaction with 1.27 MeV deuterons were used for the determination of the interaction yields from Nb and C, respectively. As a function of temperature the half widths at half maximum psisub(1/2) of the angular scans for Nb clearly increased with decreasing temperature in the range from 295 K to 78 K and then remained nearly constant down to 4 K. As a function of C-vacancy concentration in the range x = 0.98-0.90 psisub(1/2) also clearly decreased and then remained approximately constant in the range of x = 0.90-0.82. The C-yield did not depend on the C-concentration. The results of the channeling experiments were interpreted by Monte-Carlo-simulation calculations. A linear increase of the mean static three-dimensional displacements of the Nb-atoms form 0.025 Angstroem to 0.10 Angstroem was found in the concentration range of x = 0.98-0.90 and then the values remained nearly constant in the range of 0.90-0.82. The static displacements of the C-atoms lay below the detection limit of 0.025 Angstroem. The strain field around a vacancy for low vacancy concentrations (x = 0.98-0.96) was calculated employing the Kanzaki-method. (orig./GSCH) [de

  16. Small-scale gravity waves in ER-2 MMS/MTP wind and temperature measurements during CRYSTAL-FACE

    Directory of Open Access Journals (Sweden)

    L. Wang

    2006-01-01

    Full Text Available Lower stratospheric wind and temperature measurements made from NASA's high-altitude ER-2 research aircraft during the CRYSTAL-FACE campaign in July 2002 were analyzed to retrieve information on small scale gravity waves (GWs at the aircraft's flight level (typically ~20 km altitude. For a given flight segment, the S-transform (a Gaussian wavelet transform was used to search for and identify small horizontal scale GW events, and to estimate their apparent horizontal wavelengths. The horizontal propagation directions of the events were determined using the Stokes parameter method combined with the cross S-transform analysis. The vertical temperature gradient was used to determine the vertical wavelengths of the events. GW momentum fluxes were calculated from the cross S-transform. Other wave parameters such as intrinsic frequencies were calculated using the GW dispersion relation. More than 100GW events were identified. They were generally high frequency waves with vertical wavelength of ~5 km and horizontal wavelength generally shorter than 20 km. Their intrinsic propagation directions were predominantly toward the east, whereas their ground-based propagation directions were primarily toward the west. Among the events, ~20% of them had very short horizontal wavelength, very high intrinsic frequency, and relatively small momentum fluxes, and thus they were likely trapped in the lower stratosphere. Using the estimated GW parameters and the background winds and stabilities from the NCAR/NCEP reanalysis data, we were able to trace the sources of the events using a simple reverse ray-tracing. More than 70% of the events were traced back to convective sources in the troposphere, and the sources were generally located upstream of the locations of the events observed at the aircraft level. Finally, a probability density function of the reversible cooling rate due to GWs was obtained in this study, which may be useful for cirrus cloud models.

  17. Pyroelectric Properties of Potassium and Rubidium Titanyl-Arsenate Single Crystals in the Temperature Range of 4.2-300 K

    Energy Technology Data Exchange (ETDEWEB)

    Shaldin, Yu. V., E-mail: yuri1999@rambler.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Matyjasik, S. [International Laboratory of Strong Magnetic Fields and Low Temperatures (Poland); Novikova, N. E. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Tseitlin, M.; Mozhaev, E. [Ariel University Center of Samaria (Israel); Roth, M. [Hebrew University, School of Applied Sciences (Israel)

    2010-11-15

    The temperature dependences of the pyroelectric coefficients of KTiOAsO{sub 4} and RbTiOAsO{sub 4} single crystals grown by flux crystallization have been investigated in the temperature range of 4.2-300 K. With an increase in temperature, superionic conductivity first arises in KTiOAsO4 (at T > 200 K) and then (at T > 270 K) in RbTiOAsO{sub 4}. This conductivity is much higher in the samples polarized at T = 4.2 K. An exponential change in the crystal resistivity along the polar direction is simultaneously observed. The results of measurements in the range of 4.2-200 K indicate larger values of pyroelectric coefficients when compared with potassium and rubidium titanyl-phosphate crystals. A correlation between the pyroelectric coefficients and a change in the lattice constants at isomorphic substitutions of K atoms for Rb and P atoms for As has been revealed within the symmetry approach.

  18. Vacancy formation energies in close-packed crystals correlated with melting temperature via thermodynamics and liquid structure

    International Nuclear Information System (INIS)

    Rashid, R.I.M.A.; March, N.H.

    1988-08-01

    In earlier work, the vacancy formation energy E v in close-packed crystals, in units of the thermal energy k B T m at the melting temperature T m , has been connected with compressibility and specific heats, plus terms dependent on the liquid structure at T m . Here, this connection has been examined quantitatively for (a) the insulating condensed rare gases Ne, Ar and Kr, and (b) a variety of close-packed metals. For case (a), E v /k B T m can be calculated directly from thermodynamic data to obtain agreement with experiment for Ar and Kr, though not for Ne. A 'residual' contribution is estimated for Ar and Kr from diffraction and computer experiments on the density dependence of the liquid pair correlation function and is shown to be very small. Agreement is less impressive for case (b) for the eight close-packed metals for which all data required is known, the thermodynamic formula giving an average value E v /k B T m =7.8+-1.1 whereas experiment yields 9.4+-1.8. However, for the body-centred cubic alkalis the thermodynamic average value of 4.5+-0.5 is much lower than the experimental value 11.5+-2.0 consistent with the known role of ionic relaxation round the vacancy in such open structures. (author). 16 refs, 2 tabs

  19. High temperature creep of single crystals of gold, silver and solid solution gold silver 50-50

    International Nuclear Information System (INIS)

    Dorizzi, Paul

    1973-01-01

    We have studied in compression creep along a direction, single crystals of gold, silver and a 50-50 gold-silver solid solution. The experiments were made at temperatures above 0.7 Tf. We have shown that under these conditions and for these three metals a new slip system is operating: the deformation is due to the slip of dislocations having a 1/2 burgers vector on the {110} planes. For gold the activation energy for creep is equal to the self-diffusion energy. We found the same result for silver when the contribution of divacancies to the self-diffusion energy is taken into account. For the alloy the activation energy for creep is very close to the self-diffusion energy of gold in a 50-50 gold-silver alloy, gold being the slower diffusing species in the alloy. The curves giving the creep rate versus the stress can be fitted with the following laws: ε 0 = σ 5 for gold; ε 0 = σ 2,2 for silver and ε 0 = σ 2,5 for the alloy. The dislocation substructure was studied using the crystalline contrast given by the electron microprobe. This new method gives images which are very sensitive to the sub-grains misorientation. The substructure is made of parallelepipedic cells divided by tilt boundaries that are perpendicular to the {110} slip planes. (author) [fr

  20. Growth of high phase-match temperature LiNbO3 single crystals. Annual report for period ending March 15, 1978

    International Nuclear Information System (INIS)

    Kway, W.L.; Feigelson, R.S.

    1978-09-01

    LiNbO 3 crystal with T/sub pm/ greater than or equal to 180 0 C together with excellent phase matching characteristics and a high degree of optical homogeneity can be grown by the Czochralski technique with the following set of growth parameters: a melt composition of .54 Li 2 O/.46 Nb 2 O 5 doped with 1.0 mole % MgO; a growth rate of 2 mm/hr or less; positive axial and radial temperature gradients; and a crystal rotation rate of 50 rpm or higher to provide for a planar solid-liquid growth interface

  1. Growth of (CH$_3$)$_2$NH$_2$CuCl$_3$ single crystals using evaporation method with different temperatures and solvents

    OpenAIRE

    Chen, L. M.; Tao, W.; Zhao, Z. Y.; Li, Q. J.; Ke, W. P.; Wang, X. M.; Liu, X. G.; Fan, C.; Sun, X. F.

    2013-01-01

    The bulk single crystals of of low-dimensional magnet (CH$_3$)$_2$NH$_2$CuCl$_3$ (DMACuCl$_3$ or MCCL) are grown by a slow evaporation method with different kinds of solvents, different degrees of super-saturation of solution and different temperatures of solution, respectively. Among three kinds of solvent, methanol, alcohol and water, alcohol is found to be the best one for growing MCCL crystals because of its structural similarity to the raw materials and suitable evaporation rate. The bes...

  2. Crystallization Temperatures of Lower Crustal Gabbros from the Oman Ophiolite and the Persistence of the 'Mush Zone' at Intermediate/Fast Spreading Ridges

    Science.gov (United States)

    VanTongeren, J. A.

    2017-12-01

    Oceanic crust is formed when mantle-derived magmas are emplaced at the ridge axis, a zone of intense rifting and extension. Magmas begin to cool and crystallize on-axis, forming what is termed the "Mush Zone", a region of partially molten rocks. Several attempts have been made to understand the nature of the Mush Zone at fast spreading mid-ocean ridges, specifically how much partial melt exists and how far off-axis the Mush Zone extends. Geophysical estimates of P-wave velocity perturbations at the East Pacific Rise show a region of low velocity approximately 1.5-2.5 km off-axis, which can be interpreted to be the result of higher temperature [e.g. Dunn et al., 2000, JGR] or the existence of partial melt. New petrological and geochemical data and methods allow for the calculation of the lateral extent of the Mush Zone in the lower oceanic crust on exposed sections collected from the Oman ophiolite, a paleo-fast/intermediate spreading center. I will present new data quantifying the crystallization temperatures of gabbros from the Wadi Khafifah section of lower oceanic gabbros from the Oman ophiolite. Crystallization temperatures are calculated with the newly developed plagioclase-pyroxene REE thermometer of Sun and Liang [2017, Contrib. Min. Pet.]. There does not appear to be any systematic change in the crystallization temperature of lower crustal gabbros with depth in the crust. In order to quantify the duration of crystallization and the lateral extent of the Mush Zone of the lower crust, crystallization temperatures are paired with estimates of the solidus temperature and cooling rate determined from the same sample, previously constrained by the Ca diffusion in olivine geothermometer/ geospeedometer [e.g. VanTongeren et al., 2008 EPSL]. There is no systematic variation in the closure temperature of Ca in olivine, or the cooling rate to the 800°C isotherm. These results show that gabbros throughout the lower crust of the Oman ophiolite remain in a partially

  3. Effects of temperature changes and stress loading on the mechanical and shape memory properties of thermoplastic materials with different glass transition behaviours and crystal structures.

    Science.gov (United States)

    Iijima, Masahiro; Kohda, Naohisa; Kawaguchi, Kyotaro; Muguruma, Takeshi; Ohta, Mitsuru; Naganishi, Atsuko; Murakami, Takashi; Mizoguchi, Itaru

    2015-12-01

    To investigate the effects of temperature changes and stress loading on the mechanical and shape memory properties of thermoplastic materials with different glass transition behaviours and crystal structures. Five thermoplastic materials, polyethylene terephthalate glycol (Duran®, Scheu Dental), polypropylene (Hardcast®, Scheu Dental), and polyurethane (SMP MM®, SMP Technologies) with three different glass transition temperatures (T g) were selected. The T g and crystal structure were assessed using differential scanning calorimetry and X-ray diffraction. The deterioration of mechanical properties by thermal cycling and the orthodontic forces during stepwise temperature changes were investigated using nanoindentation testing and custom-made force-measuring system. The mechanical properties were also evaluated by three-point bending tests; shape recovery with heating was then investigated. The mechanical properties for each material were decreased significantly by 2500 cycles and great decrease was observed for Hardcast (crystal plastic) with higher T g (155.5°C) and PU 1 (crystalline or semi-crystalline plastic) with lower T g (29.6°C). The Duran, PU 2, and PU 3 with intermediate T g (75.3°C for Duran, 56.5°C for PU 2, and 80.7°C for PU 3) showed relatively stable mechanical properties with thermal cycling. The polyurethane polymers showed perfect shape memory effect within the range of intraoral temperature changes. The orthodontic force produced by thermoplastic appliances decreased with the stepwise temperature change for all materials. Orthodontic forces delivered by thermoplastic appliances may influence by the T g of the materials, but not the crystal structure. Polyurethane is attractive thermoplastic materials due to their unique shape memory phenomenon, but stress relaxation with temperature changes is expected. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For

  4. Schottky barrier diode based on β-Ga2O3 (100) single crystal substrate and its temperature-dependent electrical characteristics

    Science.gov (United States)

    He, Qiming; Mu, Wenxiang; Dong, Hang; Long, Shibing; Jia, Zhitai; Lv, Hangbing; Liu, Qi; Tang, Minghua; Tao, Xutang; Liu, Ming

    2017-02-01

    The Pt/β-Ga2O3 Schottky barrier diode and its temperature-dependent current-voltage characteristics were investigated for power device application. The edge-defined film-fed growth (EFG) technique was utilized to grow the (100)-oriented β-Ga2O3 single crystal substrate that shows good crystal quality characterized by X-ray diffraction and high resolution transmission electron microscope. Ohmic and Schottky electrodes were fabricated by depositing Ti and Pt metals on the two surfaces, respectively. Through the current-voltage (I-V) measurement under different temperature and the thermionic emission modeling, the fabricated Pt/β-Ga2O3 Schottky diode was found to show good performances at room temperature, including rectification ratio of 1010, ideality factor (n) of 1.1, Schottky barrier height (ΦB) of 1.39 eV, threshold voltage (Vbi) of 1.07 V, ON-resistance (RON) of 12.5 mΩ.cm2, forward current density at 2 V (J@2V) of 56 A/cm2, and saturation current density (J0) of 2 × 10-16 A/cm2. The effective donor concentration Nd - Na was calculated to be about 2.3 × 1014 cm3. Good temperature dependent performance was also found in the device. The Schottky barrier height was estimated to be about 1.3 eV-1.39 eV at temperatures ranging from room temperature to 150 °C. With increasing temperature, parameters such as RON and J@2V become better, proving that the diode can work well at high temperature. The EFG grown β-Ga2O3 single crystal is a promising material to be used in the power devices.

  5. On the Efficiency of Individualized Theta/Beta Ratio Neurofeedback Combined with Forehead EMG Training in ADHD Children

    Directory of Open Access Journals (Sweden)

    Olga M. Bazanova

    2018-01-01

    Full Text Available Background: Neurofeedback training (NFT to decrease the theta/beta ratio (TBR has been used for treating hyperactivity and impulsivity in attention deficit hyperactivity disorder (ADHD; however, often with low efficiency. Individual variance in EEG profile can confound NFT, because it may lead to influencing non-relevant activity, if ignored. More importantly, it may lead to influencing ADHD-related activities adversely, which may even result in worsening ADHD symptoms. Electromyogenic (EMG signal resulted from forehead muscles can also explain the low efficiency of the NFT in ADHD from both practical and psychological point-of-view. The first aim of this study was to determine EEG and EMG biomarkers most related to the main ADHD characteristics, such as impulsivity and hyperactivity. The second aim was to confirm our hypothesis that the efficiency of the TBR NFT can be increased by individual adjustment of the frequency bands and simultaneous training on forehead muscle tension.Methods: We recruited 94 children diagnosed with ADHD (ADHD and 23 healthy controls (HC. All participants were male and aged between six and nine. Impulsivity and attention were assessed with Go/no-Go task and delayed gratification task, respectively; and 19-channel EEG and forehead EMG were recorded. Then, the ADHD group was randomly subdivided into (1 standard, (2 individualized, (3 individualized+EMG, and (4 sham NFT (control groups. The groups were compared based on TBR and EEG alpha activity, as well as hyperactivity and impulsivity three times: pre-NFT, post-NFT and 6 months after the NFT (follow-up.Results: ADHD children were characterized with decreased individual alpha peak frequency, alpha bandwidth and alpha amplitude suppression magnitude, as well as with increased alpha1/alpha2 (a1/a2 ratio and scalp muscle tension when c (η2 ≥ 0.212. All contingent TBR NFT groups exhibited significant NFT-related decrease in TBR not evident in the control group. Moreover

  6. On the Efficiency of Individualized Theta/Beta Ratio Neurofeedback Combined with Forehead EMG Training in ADHD Children.

    Science.gov (United States)

    Bazanova, Olga M; Auer, Tibor; Sapina, Elena A

    2018-01-01

    Background: Neurofeedback training (NFT) to decrease the theta/beta ratio (TBR) has been used for treating hyperactivity and impulsivity in attention deficit hyperactivity disorder (ADHD); however, often with low efficiency. Individual variance in EEG profile can confound NFT, because it may lead to influencing non-relevant activity, if ignored. More importantly, it may lead to influencing ADHD-related activities adversely, which may even result in worsening ADHD symptoms. Electromyogenic (EMG) signal resulted from forehead muscles can also explain the low efficiency of the NFT in ADHD from both practical and psychological point-of-view. The first aim of this study was to determine EEG and EMG biomarkers most related to the main ADHD characteristics, such as impulsivity and hyperactivity. The second aim was to confirm our hypothesis that the efficiency of the TBR NFT can be increased by individual adjustment of the frequency bands and simultaneous training on forehead muscle tension. Methods: We recruited 94 children diagnosed with ADHD (ADHD) and 23 healthy controls (HC). All participants were male and aged between six and nine. Impulsivity and attention were assessed with Go/no-Go task and delayed gratification task, respectively; and 19-channel EEG and forehead EMG were recorded. Then, the ADHD group was randomly subdivided into (1) standard, (2) individualized, (3) individualized+EMG, and (4) sham NFT (control) groups. The groups were compared based on TBR and EEG alpha activity, as well as hyperactivity and impulsivity three times: pre-NFT, post-NFT and 6 months after the NFT (follow-up). Results: ADHD children were characterized with decreased individual alpha peak frequency, alpha bandwidth and alpha amplitude suppression magnitude, as well as with increased alpha1/alpha2 (a1/a2) ratio and scalp muscle tension when c (η 2 ≥ 0.212). All contingent TBR NFT groups exhibited significant NFT-related decrease in TBR not evident in the control group. Moreover

  7. Determination of temperature-dependent thermal conductivity of a BaSnO{sub 3−δ} single crystal by using the 3ω method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung Joon; Kim, Tai Hoon; Lee, Woong-Jhae; Chai, Yisheng; Kim, Jae Wook; Jwa, Yeon Jae; Chung, Sukhwan; Kim, Seon Joong; Sohn, Egon [Center for Novel States of Complex Materials Research, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Lee, Seung Min [Hanbeam Corporation Ltd, Iui-dong 906-5, Yeongtong-gu, Suwon-si, Gyeonggi-do (Korea, Republic of); Choi, Ki-Young [Center for Novel States of Complex Materials Research, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Kim, Kee Hoon, E-mail: khkim@phya.snu.ac.kr [Center for Novel States of Complex Materials Research, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2014-06-01

    Highlights: • This is the first report about thermal conductivity of BaSnO{sub 3−δ} single crystals. • We report the successful κ measurement of the crystals by employing the 3ω method. • The BaSnO{sub 3−δ} single crystal can be a good perovskite substrate with high κ. • We found that phonons mainly contribute to the heat transport in BaSnO{sub 3−δ}. - Abstract: The single crystal of the electron doped BaSnO{sub 3−δ} system has been recently found to have high electrical mobility (up to 320 cm{sup 2} V{sup −1} s{sup −1}) at room temperature and excellent oxygen stability. Although thermal conductivity (κ) of the BaSnO{sub 3−δ} single crystal is an important physical quantity, the κ measurement by the conventional DC method has been difficult due to the limited crystal size. Herein, we report the first measurement of κ by using the 3ω method from ∼20 to 300 K in the oxygen deficient BaSnO{sub 3−δ} single crystal with carrier concentration of ∼10{sup 18} cm{sup −3}. We found that κ is proportional to T{sup −1} above 50 K, indicating that phonons mainly contribute to the heat transport. Moreover, the electronic contribution is determined as ∼4% of the measured κ from the Wiedemann–Franz law. The κ value is 0.132 W cm{sup −1} K{sup −1} at room temperature and is increased progressively at lower temperatures, becoming overall larger than that of the SrTiO{sub 3} single crystal. Our results thus point out that BaSnO{sub 3−δ} can be a good substrate for growing transparent electronic thin films with the perovskite structure.

  8. Thermal expansion behavior of empressite, AgTe: A structural study by means of in situ high-temperature single-crystal X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Bindi, Luca [Museo di Storia Naturale, sez. di Mineralogia, Universita di Firenze, Via La Pira 4, I-50121 Firenze (Italy)], E-mail: luca.bindi@unifi.it

    2009-04-03

    The crystal structure of empressite, AgTe, a rare silver telluride, has been investigated by in situ X-ray single-crystal diffraction methods within the temperature range 298-463 K. AgTe remains orthorhombic, space group Pmnb (Pnma as standard), and shows only normal thermal expansion over the entire temperature range. The unit-cell parameters show a gradual increase with the increase of temperature. Slight adjustments in the geometry of Ag-tetrahedra and in the crystal-chemical environment of tellurium atoms occur in a continuous way without abrupt structural changes. The coefficients of thermal expansion along various axes are: {alpha}{sub a} = 1.5 x 10{sup -5} K{sup -1}, {alpha}{sub b} = 3.0 x 10{sup -5} K{sup -1}, {alpha}{sub c} = 2.2 x 10{sup -5} K{sup -1}, and the bulk thermal expansion coefficient {alpha}{sub V} is 5.4 x 10{sup -5} K{sup -1} for the temperature range 298-463 K.

  9. Novel Design Integrating a Microwave Applicator into a Crystallizer for Rapid Temperature Cycling. A Direct Nucleation Control Study

    NARCIS (Netherlands)

    Kacker, R.; Radoiu, Marilena; Kramer, H.J.M.

    2017-01-01

    The control of nucleation in crystallization processes is a challenging task due to the often lacking knowledge on the process kinetics. Inflexible (predetermined) control strategies fail to grow the nucleated crystals to the desired quality because of the variability in the process conditions,

  10. SQUID picovoltometry of single crystal Bi2Sr2CaCu2O(8+delta) - Observation of the crossover from high-temperature Arrhenius to low-temperature vortex-glass behavior

    Science.gov (United States)

    Safar, H.; Gammel, P. L.; Bishop, D. J.; Mitzi, D. B.; Kapitulnik, A.

    1992-04-01

    A SQUID voltmeter has been used to measure current-voltage curves in untwinned crystals of Bi2Sr2CaCu2O(8+delta) as a function of temperature and magnetic field. The data show a clear crossover from high-temperature Arrhenius behavior to a critical region associated with the low-temperature three-dimensional vortex-glass phase transition. The critical exponents v(z - 1) = 7 +/- 1 in this system are in accord with theoretical models and previous measurements in YBa2Cu3O7. The width of the critical region collapses below 2 T, reflecting the changing role of dimensionality with field.

  11. Apparatus for mounting crystal

    Science.gov (United States)

    Longeway, Paul A.

    1985-01-01

    A thickness monitor useful in deposition or etching reactor systems comprising a crystal-controlled oscillator in which the crystal is deposited or etched to change the frequency of the oscillator. The crystal rests within a thermally conductive metallic housing and arranged to be temperature controlled. Electrode contacts are made to the surface primarily by gravity force such that the crystal is substantially free of stress otherwise induced by high temperature.

  12. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    Energy Technology Data Exchange (ETDEWEB)

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  13. Crystallization In Multicomponent Glasses

    International Nuclear Information System (INIS)

    Kruger, A.A.; Hrma, P.R.

    2009-01-01

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  14. Low-Temperature Band Transport and Impact of Contact Resistance in Organic Field-Effect Transistors Based on Single-Crystal Films of Ph-BTBT-C10

    Science.gov (United States)

    Cho, Joung-min; Mori, Takehiko

    2016-06-01

    Transistors based on single-crystal films of 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10) fabricated using the blade-coating method are investigated by the four-probe method down to low temperatures. The four-probe mobility is as large as 18 cm2/V s at room temperature, and increases to 45 cm2/V s at 80 K. At 60 K the two-probe mobility drops abruptly by about 50%, but the mobility drop is mostly attributed to the increase of the source resistance. The carrier transport in the present single-crystal film is regarded as essentially bandlike down to 30 K.

  15. Ordered distribution of I and Cl in the low-temperature crystal structure of mutnovskite, Pb4As2S6ICl: An X-ray single-crystal study

    International Nuclear Information System (INIS)

    Bindi, Luca; Garavelli, Anna; Pinto, Daniela; Pratesi, Giovanni; Vurro, Filippo

    2008-01-01

    To study the temperature-dependent structural changes and to analyze the crystal chemical behavior of the halogens as a function of temperature, a crystal of the recently discovered mineral mutnovskite, ideally Pb 2 AsS 3 (I,Cl,Br), has been investigated by X-ray single-crystal diffraction methods at 300 and 110 K. At room temperature (RT) mutnovskite was confirmed to possess a centrosymmetric structure-type, space group Pnma, while at low temperature (110 K) it adopts a non-centrosymmetric orthorhombic structure-type, space group Pnm2 1 , with a=11.5394(9) A, b=6.6732(5) A, c=9.3454(7) A, V=719.64(9) A 3 and Z=2. Mutnovskite reconverts to the centrosymmetric-type upon returning to RT thus indicating that the phase transition is completely reversible in character. The refinement of the LT-structure leads to a residual factor R=0.0336 for 1827 independent observed reflections [F o >4σ(F o )] and 80 variables. The crystal structure of cooled mutnovskite is topologically identical to that observed at RT and the slight structural changes occurring during the phase transition Pnma→Pnm2 1 are mainly restricted to the coordination polyhedra around Pb. The structure solution revealed that I and Cl are ordered into two specific sites. Indeed, the unique mixed (I,Cl) position in the RT-structure (Wyckoff position 4c) transforms into two 2a Wyckoff positions in the LT-structure hosting I and Cl, respectively. - Graphical abstract: In the crystal structure of mutnovskite at 110 K the two halogens I and Cl are ordered into two specific sites and only slight changes in the coordination environment around Pb atoms occur during the phase transition Pnma→Pnm2 1 from the RT-structure to the LT-structure. Two kinds of layers alternating along a are present in the LT-structure: Layer I contains Cl atoms and [001] columns of Pb1 and Pb4 prisms, layer II contains I atoms and [001] columns of Pb2 and Pb3 prisms

  16. Comparison of bone-conducted vibration for eliciting ocular vestibular-evoked myogenic potentials: forehead versus mastoid tapping.

    Science.gov (United States)

    Tseng, Chia-Chen; Wang, Shou-Jen; Young, Yi-Ho

    2012-02-01

    This study compared bone-conducted vibration (BCV) stimuli at forehead (Fz) and mastoid sites for eliciting ocular vestibular-evoked myogenic potentials (oVEMPs). Prospective study. University hospital. Twenty healthy subjects underwent oVEMP testing via BCV stimuli at Fz and mastoid sites. Another 50 patients with unilateral Meniere's disease also underwent oVEMP testing. All healthy subjects showed clear oVEMPs via BCV stimulation regardless of the tapping sites. The right oVEMPs stimulated by tapping at the right mastoid had earlier nI and pI latencies and a larger nI-pI amplitude compared with those stimulated by tapping at the Fz and left mastoid. Similar trends were also observed in left oVEMPs. However, the asymmetry ratio did not differ significantly between the ipsilateral mastoid and Fz sites. Clinically, tapping at the Fz revealed absent oVEMPs in 28% of Meniere's ears, which decreased to 16% when tapping at the ipsilesional (hydropic) mastoid site, exhibiting a significant difference. Tapping at the ipsilateral mastoid site elicits earlier oVEMP latencies and larger oVEMP amplitudes when compared with tapping at the Fz site. Thus, tapping at the Fz site is suggested to screen for the otolithic function, whereas tapping at the ipsilesional mastoid site is suitable for evaluating residual otolithic function.

  17. Interfrontal encephalocele: a rare feature of forehead in hydrocephalic myelomeningocele patients. Clinical feature, probable mechanisms, and management.

    Science.gov (United States)

    Nejat, Farideh; Kamali, Shahab; El Khashab, Mostafa

    2013-08-01

    Myelomeningocele is a complex central nervous system malformation mostly associated with other neural and extraneural anomalies. A rare special feature of the forehead and skull was observed in myelomeningocele. Here, we present several patients with myelomeningocele, severe hydrocephalus, and interfrontal encephalocele accompanied by metopic suture widening and abnormally shaped frontal bones. Five children with this feature were enrolled in this series. The age, sex, location of myelomeningocele sac, neurological deficits, hydrocephalus and history of shunt surgery, and follow-up period were evaluated. Patients were aged from 1 to 12 months (mean, 6 months). All patients were male. Most sacs were located in lumbar and lumbosacral areas. Neurological deficits varying from only sphincter problem to paraplegia were found in all patients. Hydrocephalus was found in all children that needed a shunt procedure. Asymptomatic Chiari malformation, interfrontal encephalocele, and corpus callosum agenesis were evident in five, five, and three patients, respectively. Anterior fontanel anomalies known as interfrontal encephalocele associated with myelomeningocele have been reported before. The patients have an open metopic suture extending widely to the nasal radix producing hypertelorism accompanied by interfrontal herniation of frontal lobes. The associated hydrocephalus exaggerates the anomaly. Treatment of accompanying hydrocephalus is advised to decrease the severity of frontal lobe herniation. Some patients may need frontal bone reconstruction surgery to provide cosmetic correction at the place of the midline frontal bone defect.

  18. A comparative evaluation of adaptive noise cancellation algorithms for minimizing motion artifacts in a forehead-mounted wearable pulse oximeter.

    Science.gov (United States)

    Comtois, Gary; Mendelson, Yitzhak; Ramuka, Piyush

    2007-01-01

    Wearable physiological monitoring using a pulse oximeter would enable field medics to monitor multiple injuries simultaneously, thereby prioritizing medical intervention when resources are limited. However, a primary factor limiting the accuracy of pulse oximetry is poor signal-to-noise ratio since photoplethysmographic (PPG) signals, from which arterial oxygen saturation (SpO2) and heart rate (HR) measurements are derived, are compromised by movement artifacts. This study was undertaken to quantify SpO2 and HR errors induced by certain motion artifacts utilizing accelerometry-based adaptive noise cancellation (ANC). Since the fingers are generally more vulnerable to motion artifacts, measurements were performed using a custom forehead-mounted wearable pulse oximeter developed for real-time remote physiological monitoring and triage applications. This study revealed that processing motion-corrupted PPG signals by least mean squares (LMS) and recursive least squares (RLS) algorithms can be effective to reduce SpO2 and HR errors during jogging, but the degree of improvement depends on filter order. Although both algorithms produced similar improvements, implementing the adaptive LMS algorithm is advantageous since it requires significantly less operations.

  19. Efficacy and Safety of OnabotulinumtoxinA Treatment of Forehead Lines: A Multicenter, Randomized, Dose-Ranging Controlled Trial.

    Science.gov (United States)

    Solish, Nowell; Rivers, Jason K; Humphrey, Shannon; Muhn, Channy; Somogyi, Chris; Lei, Xiaofang; Bhogal, Meetu; Caulkins, Carrie

    2016-03-01

    Various onabotulinumtoxinA doses are effective in treating forehead lines (FHL), with a trend toward lower doses. To evaluate efficacy and safety of onabotulinumtoxinA dose-ranging treatment of FHL when the frontalis area and glabellar complex are treated together. Adults with moderate-to-severe FHL received onabotulinumtoxinA 40 U (FHL, 20 U; glabellar lines [GL], 20 U), 30 U (FHL, 10 U; GL, 20 U), or placebo. Response was assessed at weeks 1, 2, day 30, and monthly to day 180. Coprimary efficacy end points were investigator- and subject-assessed Facial Wrinkle Scale scores of none or mild (day 30). Patient-reported outcomes, onset/duration of effect, and adverse events (AEs) were evaluated. Responder rates (investigator/subject, respectively) were 40-U group, 91.2%/89.5%; 30-U group, 86.4%/81.4%; placebo, 1.7%/5.1%. OnabotulinumtoxinA resulted in significantly greater responder rates than placebo (p < .001). Adverse events were mild to moderate and similar between groups (most common AEs: nasopharyngitis [4.6%] and headache [4.0%]). Treatment of FHL with onabotulinumtoxinA 40 and 30 U (in frontalis and glabellar complex muscles) was tolerable, effective, and sustained. Both doses significantly reduced FHL severity; however, the 40-U dose demonstrated a trend toward greater sustained benefit and longer duration of effect versus the 30-U dose, with similar AE rates.

  20. Understanding the importance of the temperature dependence of viscosity on the crystallization dynamics in the Ge2Sb2Te5 phase-change material

    Science.gov (United States)

    Aladool, A.; Aziz, M. M.; Wright, C. D.

    2017-06-01

    The crystallization dynamics in the phase-change material Ge2Sb2Te5 is modelled using the more detailed Master equation method over a wide range of heating rates commensurate with published ultrafast calorimetry experiments. Through the attachment and detachment of monomers, the Master rate equation naturally traces nucleation and growth of crystallites with temperature history to calculate the transient distribution of cluster sizes in the material. Both the attachment and detachment rates in this theory are strong functions of viscosity, and thus, the value of viscosity and its dependence on temperature significantly affect the crystallization process. In this paper, we use the physically realistic Mauro-Yue-Ellison-Gupta-Allan viscosity model in the Master equation approach to study the role of the viscosity model parameters on the crystallization dynamics in Ge2Sb2Te5 under ramped annealing conditions with heating rates up to 4 × 104 K/s. Furthermore, due to the relatively low computational cost of the Master equation method compared to atomistic level computations, an iterative numerical approach was developed to fit theoretical Kissinger plots simulated with the Master equation system to experimental Kissinger plots from ultrafast calorimetry measurements at increasing heating rates. This provided a more rigorous method (incorporating both nucleation and growth processes) to extract the viscosity model parameters from the analysis of experimental data. The simulations and analysis revealed the strong coupling between the glass transition temperature and fragility index in the viscosity and crystallization models and highlighted the role of the dependence of the glass transition temperature on the heating rate for the accurate estimation of the fragility index of phase-change materials from the analysis of experimental measurements.

  1. The Use of Quasi-Isothermal Modulated Temperature Differential Scanning Calorimetry for the Characterization of Slow Crystallization Processes in Lipid-Based Solid Self-Emulsifying Systems

    OpenAIRE

    Otun, Sarah O.; Meehan, Elizabeth; Qi, Sheng; Craig, Duncan Q. M.

    2014-01-01

    Purpose Slow or incomplete crystallization may be a significant manufacturing issue for solid lipid-based dosage forms, yet little information is available on this phenomenon. In this investigation we suggest a novel means by which slow solidification may be monitored in Gelucire 44/14 using quasi-isothermal modulated temperature DSC (QiMTDSC). Methods Conventional linear heating and cooling DSC methods were employed, along with hot stage microscopy (HSM), for basic thermal profiling of Geluc...

  2. Inorganic Lead Halide Perovskite Single Crystals: Phase-Selective Low-Temperature Growth, Carrier Transport Properties, and Self-Powered Photodetection

    KAUST Repository

    Saidaminov, Makhsud I.

    2016-12-06

    A rapid, low-temperature, and solution-based route is developed for growing large-sized cesium lead halide perovskite single crystals under ambient conditions. An ultralow minority carrier concentration was measured in CsPbBr3 (≈108 holes per cm3, much lower than in any other lead halide perovskite and crystalline silicon), which enables to realize self-powered photodetectors with a high ON/OFF ratio (105).

  3. Temperature dependence of twinning stress – analogy between Cu–Ni–Al and Ni–Mn–Ga shape memory single crystals

    Czech Academy of Sciences Publication Activity Database

    Vronka, Marek; Seiner, Hanuš; Heczko, Oleg

    2017-01-01

    Roč. 97, č. 18 (2017), s. 1479-1497 ISSN 1478-6435 R&D Projects: GA ČR GB14-36566G; GA ČR GA15-00262S Institutional support: RVO:68378271 ; RVO:61388998 Keywords : SMA * single crystal * twinning * martensite * twinning stress * temperature dependence Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.505, year: 2016

  4. Low-temperature growth of polycrystalline Ge thin film on glass by in situ deposition and ex situ solid-phase crystallization for photovoltaic applications

    International Nuclear Information System (INIS)

    Tsao, Chao-Yang; Weber, Juergen W.; Campbell, Patrick; Widenborg, Per I.; Song, Dengyuan; Green, Martin A.

    2009-01-01

    Poly-crystalline germanium (poly-Ge) thin films have potential for lowering the manufacturing cost of photovoltaic devices especially in tandem solar cells, but high crystalline quality would be required. This work investigates the crystallinity of sputtered Ge thin films on glass prepared by in situ growth and ex situ solid-phase crystallization (SPC). Structural properties of the films were characterized by Raman, X-ray diffraction and ultraviolet-visible reflectance measurements. The results show the transition temperature from amorphous to polycrystalline is between 255 deg. C and 280 deg. C for in situ grown poly-Ge films, whereas the transition temperature is between 400 deg. C and 500 deg. C for films produced by SPC for a 20 h annealing time. The in situ growth in situ crystallized poly-Ge films at 450 deg. C exhibit significantly better crystalline quality than those formed by solid-phase crystallization at 600 deg. C. High crystalline quality at low substrate temperature obtained in this work suggests the poly-Ge films could be promising for use in thin film solar cells on glass.

  5. Bindi tattoo on forehead: success with modified R-20 technique using low fluence q-switched nd yag laser: a case report.

    Science.gov (United States)

    Zawar, Vijay; Sarda, Aarti; De, Abhishek

    2014-01-01

    Bindi tattoo on the forehead, is one of the cultural practice in Indian women from rural areas. Many patients are not pleased with the appearance of their tattoo and thus seek removal. The development of quality-switched lasers has revolutionized the removal of unwanted tattoos. However, despite multiple treatment sessions, the efficacy is often found to be limited. We herein report a case of green-blue bindi tattoo which failed to clear after 8 sessions of Q-switched Nd YAG laser. The tattoo significantly cleared with R-20 method using low fluence Q-switched Nd YAG Laser. R-20 technique seems to be an effective method of tattoo removal and might be a boon for patients who are reluctant to pursue laser treatment because of fear of expenditure, side effects and uncertainty of result. We report efficacy of R-20 technique for a bindi tattoo on forehead.

  6. Effect of low irradiation temperature on the thermoluminescent response of doped crystal NaCl:XCl2 :MnCl2(X=Ca, Cd)

    International Nuclear Information System (INIS)

    Ortiz M, A.; Cruz Z, E.; Furetta, C.; Kitis, G.

    2009-10-01

    Production of crystalline materials suitable thermoluminescent properties over a wide range of doses is becoming more important to evaluate different radiation fields. However, the thermoluminescence response and the structure of the glow curves may be modified by the participation of defects to low irradiation temperature. In this work it is analyzed the effect of the irradiation temperature, 77 and 200 K on the thermoluminescence response of crystal NaCl:XCl 2 :MnCl 2 (X=Ca, Cd) doubly doped. The glow curves obtained were analyzed using a deconvolution program of CGCD, and the response linearity was analyzed by supra linearity index. (Author)

  7. Surgical Excision with Forehead Flap as Single Modality Treatment for Basal Cell Cancer of Central Face: Single Institutional Experience of 50 Cases

    Directory of Open Access Journals (Sweden)

    Jagdeep Rao

    2014-01-01

    Full Text Available Basal cell carcinoma (BCC is the most common skin cancer worldwide. The WHO has defined it as “a locally invasive, slowly spreading tumor which rarely metastasizes, arising in the epidermis or hair follicles and in which the peripheral cells usually simulate the basal cells of the epidermis.” Here we discuss the management of BCCs of central face with surgical excision and reconstruction with forehead flap as single modality treatment. Material and Methods. This is a retrospective review of 50 patients who underwent surgical excision of BCC involving the facial region followed by primary reconstruction using forehead flaps at a single institution. There were 20 males and 30 females, mean age of 59 years. Results. No recurrence at primary site was observed during the follow-up of 1–4 yrs. There was no ectropion or exposure sequela. However, epiphora was evident. Size of lesions ranged from 2 to 6 cm. Keloid formation was seen in 2 (4% patients. Functional and cosmetic outcomes were satisfactory. Conclusion. For the face, the best reconstructive effort eventually fails in the face of tumor recurrence. The forehead flap represents one of the best methods for repair of extensive facial defects. Complete tumor extirpation, the primary event, is the key.

  8. Temperature and concentration quenching of Tb{sup 3+} emissions in Y{sub 4}Al{sub 2}O{sub 9} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Boruc, Z., E-mail: z.boruc@stud.elka.pw.edu.pl [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw (Poland); Fetlinski, B.; Kaczkan, M. [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw (Poland); Turczynski, S.; Pawlak, D. [Institute of Electronic Materials Technology, ul. Wolczynska 133, 01-919 Warsaw (Poland); Malinowski, M. [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw (Poland)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Spectroscopic properties of Tb{sup 3+}:Y{sub 4}Al{sub 2}O{sub 9} crystals are studied. Black-Right-Pointing-Pointer Concentration and temperature dependencies of fluorescence are investigated. Black-Right-Pointing-Pointer The cross-relaxation transfer rates are experimentally determined. Black-Right-Pointing-Pointer Strong influence of cross relaxation process on {sup 5}D{sub 3} emission quenching is observed. Black-Right-Pointing-Pointer Decays are modelled using Inokuti-Hirayama approach. - Abstract: Spectroscopic properties of trivalent terbium (Tb{sup 3+}) activated Y{sub 4}Al{sub 2}O{sub 9} (abbreviated YAM) crystals were studied. Concentration and temperature dependent emission spectra and fluorescence dynamics profiles have been investigated in YAM:Tb{sup 3+} in order to understand better processes responsible for quenching of the terbium {sup 5}D{sub 3} and {sup 5}D{sub 4} emissions. Decays were modelled using Inokuti-Hirayama approach to obtain information on the energy transfer mechanism. The cross-relaxation transfer rates were experimentally determined as a function of temperature and Tb{sup 3+} concentration. The investigation revealed strong influence of cross-relaxation process on {sup 5}D{sub 3} emission quenching. The two different processes responsible for the increase of fluorescence quenching with growing temperature were observed, both related to thermal activation energy. For temperatures above 700 K, the temperature dependence of the emission intensity ratio ({sup 5}D{sub 3}/{sup 5}D{sub 4}) becomes linear and the decay times are rapidly decreasing monotonously with increasing temperature, what is confirming the potential of Y{sub 4}Al{sub 2}O{sub 9}:Tb{sup 3+} material in high temperature luminescence thermometry.

  9. Complete sets of elastic constants and photoelastic coefficients of pure and MgO-doped lithium niobate crystals at room temperature

    International Nuclear Information System (INIS)

    Andrushchak, A. S.; Laba, H. P.; Yurkevych, O. V.; Mytsyk, B. G.; Solskii, I. M.; Kityk, A. V.; Sahraoui, B.

    2009-01-01

    This paper presents the results of ultrasonic measurements of LiNbO 3 and LiNbO 3 :MgO crystals. The tensors of piezoelectric coefficients, elastic stiffness constants, and elastic compliances are determined for both crystals at room temperature. Combining these data with the results of piezo-optical measurements, a complete set of photoelastic tensor coefficients is also calculated. Doping of LiNbO 3 crystals by MgO does not lead to a considerable modification of their elastic and photoelastic properties. However, LiNbO 3 :MgO is characterized by a considerably higher resistance with respect to powerful light radiation, making it promising for future application in acousto-optic devices that deal with superpowerful laser radiation. Presented here are the complete tensor sets of elastic constants and photoelastic coefficients of LiNbO 3 and LiNbO 3 :MgO crystals that may be used for a geometry optimization of acousto-optical interaction providing the best diffraction efficiency of acousto-optical cells made of these materials.

  10. Room-temperature single-photon sources with definite circular and linear polarizations based on single-emitter fluorescence in liquid crystal hosts

    International Nuclear Information System (INIS)

    Winkler, Justin M; Lukishova, Svetlana G; Bissell, Luke J

    2013-01-01

    Definite circular and linear polarizations of room-temperature single-photon sources, which can serve as polarization bases for quantum key distribution, are produced by doping planar-aligned liquid crystal hosts with single fluorescence emitters. Chiral 1-D photonic bandgap microcavities for a single handedness of circularly polarized light were prepared from both monomeric and oligomeric cholesteric liquid crystals. Fluorescent emitters, such as nanocrystal quantum dots, nitrogen vacancy color centers in nanodiamonds, and rare-earth ions in nanocrystals, were doped into these microcavity structures and used to produce circularly polarized fluorescence of definite handedness. Additionally, we observed circularly polarized resonances in the spectrum of nanocrystal quantum dot fluorescence at the edge of the cholesteric microcavity's photonic stopband. For this polarization we obtained a ∼4.9 enhancement of intensity compared to the polarization of the opposite handedness that propagates without photonic bandgap microcavity effects. Such a resonance is indicative of coupling of quantum dot fluorescence to the cholesteric microcavity mode. We have also used planar-aligned nematic liquid crystal hosts to align DiI dye molecules doped into the host, thereby providing a single-photon source of linear polarization of definite direction. Antibunching is demonstrated for fluorescence of nanocrystal quantum dots, nitrogen vacancy color centers, and dye molecules in these liquid crystal structures.

  11. Tailored botulinum toxin type A injections in aesthetic medicine: consensus panel recommendations for treating the forehead based on individual facial anatomy and muscle tone

    Directory of Open Access Journals (Sweden)

    Anido J

    2017-10-01

    Full Text Available Javier Anido,1 Daniel Arenas,2 Cristina Arruabarrena,3 Alfonso Domínguez-Gil,4 Carlos Fajardo,5 Mar Mira,6 Javier Murillo,7 Natalia Ribé,8 Helga Rivera,9 Sofia Ruiz del Cueto,6 Helder Silvestre,10 Marisa Tirado11 1A-Clinic, Madrid, 2Hospital Cruz Roja, Madrid, 3Clinic Cristina Arruabarrena, San Sebastiá, 4Salamanca University, Salamanca, 5Clinic Fajardo, Malaga, 6Clinic Mira+Cueto, Madrid, 7Clinic CIR, Seville, 8Institute Natalia Ribé, Barcelona, 9Clinic Helga Rivera, Vigo, Spain; 10Clinic Europa, Lisbon, Portugal; 11Clinic Derma Alemar, Castellón, Spain Background: Facial lines and wrinkles are strongly influenced by individual differences in anatomy and muscle activity and no single injection protocol will suit all patients. However, there is only limited information in the published literature on how to develop a tailored approach to botulinum toxin treatment.Methods: An expert panel of physicians was convened to establish a consensus on developing an individualized approach to treatment of the forehead with incobotulinumtoxinA. Separate treatment protocols were developed for men and women and subdivided by background level of muscle activity: kinetic, hyperkinetic, and hypertonic. Each muscle tone category was then further subdivided to take account of individual characteristics that can influence treatment.Results: Consensus members describe how to perform a dynamic assessment to optimize the dose and injection technique for each patient. A tailored treatment protocol is described for men and women with a wide range of forehead presentations. For each presentation, units of toxin as well as the precise location of injection points were defined by creating a 12-zone map of the forehead.Conclusion: These recommendations depart from traditional consensus documents by providing detailed incobotulinumtoxinA injection protocols for the forehead based on the major parameters that differ between patients, including muscular anatomy, size, and

  12. The effect of temperature on the crystallization of α-Fe2O3 particles from dense β-FeOOH suspensions

    International Nuclear Information System (INIS)

    Zic, Mark; Ristic, Mira; Music, Svetozar

    2010-01-01

    The effect of temperature on the crystallization of α-Fe 2 O 3 particles from dense β-FeOOH suspensions was monitored by 57 Fe Moessbauer spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and energy dispersive spectroscopy. Dense suspensions of very long laterally arranged β-FeOOH fibrils were obtained at 90 deg. C. Crystallization at 120 deg. C between 18 and 72 h yielded monodisperse α-Fe 2 O 3 particles of a shape close to that of double spheres with ring. The double spheres with ring showed two narrow particle size distributions. In these particles a substructure was detected, i.e., the spheres consisted of the linear chains of interconnected α-Fe 2 O 3 subparticles. With further rise in the crystallization temperature the increase in α-Fe 2 O 3 particles and porosity became pronounced. Obviously, the aggregation mechanism played an important role in the formation of α-Fe 2 O 3 particles.

  13. Plastic substrates for active matrix liquid crystal display incapable of withstanding processing temperature of over 200 C and method of fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Carey, P.G.; Smith, P.M.; Havens, J.H.; Jones, P.

    1999-01-05

    Bright-polarizer-free, active-matrix liquid crystal displays (AMLCDs) are formed on plastic substrates. The primary components of the display are a pixel circuit fabricated on one plastic substrate, an intervening liquid-crystal material, and a counter electrode on a second plastic substrate. The-pixel circuit contains one or more thin-film transistors (TFTs) and either a transparent or reflective pixel electrode manufactured at sufficiently low temperatures to avoid damage to the plastic substrate. Fabrication of the TFTs can be carried out at temperatures less than 100 C. The liquid crystal material is a commercially made nematic curvilinear aligned phase (NCAP) film. The counter electrode is comprised of a plastic substrate coated with a transparent conductor, such as indium-doped tin oxide (ITO). By coupling the active matrix with NCAP, a high-information content can be provided in a bright, fully plastic package. Applications include any low cost portable electronics containing flat displays where ruggedization of the display is desired. 12 figs.

  14. Plastic substrates for active matrix liquid crystal display incapable of withstanding processing temperature of over 200.degree. C and method of fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Carey, Paul G. (Mountain View, CA); Smith, Patrick M. (San Ramon, CA); Havens, John (San Diego, CA); Jones, Phil (Marlborough, GB)

    1999-01-01

    Bright-polarizer-free, active-matrix liquid crystal displays (AMLCDs) are formed on plastic substrates. The primary components of the display are a pixel circuit fabricated on one plastic substrate, an intervening liquid-crystal material, and a counter electrode on a second plastic substrate. The-pixel circuit contains one or more thin-film transistors (TFTs) and either a transparent or reflective pixel electrode manufactured at sufficiently low temperatures to avoid damage to the plastic substrate. Fabrication of the TFTs can be carried out at temperatures less than 100.degree. C. The liquid crystal material is a commercially made nematic curvilinear aligned phase (NCAP) film. The counter electrode is comprised of a plastic substrate coated with a transparent conductor, such as indium-doped tin oxide (ITO). By coupling the active matrix with NCAP, a high-information content can be provided in a bright, fully plastic package. Applications include any low cost portable electronics containing flat displays where ruggedization of the display is desired.

  15. Mechanisms of aluminium-induced crystallization and layer exchange upon low-temperature annealing of amorphous Si/polycrystalline Al bilayers.

    Science.gov (United States)

    Wang, J Y; Wang, Z M; Jeurgens, L P H; Mittemeijer, E J

    2009-06-01

    Aluminium-induced crystallization (ALIC) of amorphous Si and subsequent layer exchange (ALILE) occur in amorphous-Si/polycrystalline-Al bilayers (a-Si/c-Al) upon annealing at temperatures as low as 165 degrees C and were studied by X-ray diffraction and Auger electron spectroscopic depth profiling. It follows that: (i) nucleation of Si crystallization is initiated at Al grain boundaries and not at the a-Si/c-Al interface; (ii) low-temperature annealing results in a large Si grain size in the continuous c-Si layer produced by ALILE. Thermodynamic model calculations show that: (i) Si can "wet" the Al grain boundaries due to the favourable a-Si/c-Al interface energy (as compared to the Al grain-boundary energy); (ii) the wetting-induced a-Si layer at the Al grain boundary can maintain its amorphous state only up to a critical thickness, beyond which nucleation of Si crystallization takes place; and (iii) a tiny driving force controls the kinetics of the layer exchange.

  16. Final Report - Crystal Settling, Redox, and High Temperature Properties of ORP HLW and LAW Glasses, VSL-09R1510-1, Rev. 0, dated 6/18/09

    Energy Technology Data Exchange (ETDEWEB)

    Kruger, Albert A.; Wang, C.; Gan, H.; Pegg, I. L.; Chaudhuri, M.; Kot, W.; Feng, Z.; Viragh, C.; McKeown, D. A.; Joseph, I.; Muller, I. S.; Cecil, R.; Zhao, W.

    2013-11-13

    The radioactive tank waste treatment programs at the U. S. Department of Energy (DOE) have featured joule heated ceramic melter technology for the vitrification of high level waste (HLW). The Hanford Tank Waste Treatment and Immobilization Plant (WTP) employs this same basic technology not only for the vitrification of HLW streams but also for the vitrification of Low Activity Waste (LAW) streams. Because of the much greater throughput rates required of the WTP as compared to the vitrification facilities at the West Valley Demonstration Project (WVDP) or the Defense Waste Processing Facility (DWPF), the WTP employs advanced joule heated melters with forced mixing of the glass pool (bubblers) to improve heat and mass transport and increase melting rates. However, for both HLW and LAW treatment, the ability to increase waste loadings offers the potential to significantly reduce the amount of glass that must be produced and disposed and, therefore, the overall project costs. This report presents the results from a study to investigate several glass property issues related to WTP HLW and LAW vitrification: crystal formation and settling in selected HLW glasses; redox behavior of vanadium and chromium in selected LAW glasses; and key high temperature thermal properties of representative HLW and LAW glasses. The work was conducted according to Test Plans that were prepared for the HLW and LAW scope, respectively. One part of this work thus addresses some of the possible detrimental effects due to considerably higher crystal content in waste glass melts and, in particular, the impact of high crystal contents on the flow property of the glass melt and the settling rate of representative crystalline phases in an environment similar to that of an idling glass melter. Characterization of vanadium redox shifts in representative WTP LAW glasses is the second focal point of this work. The third part of this work focused on key high temperature thermal properties of

  17. Numerical study on the effect of temperature oscillations on the crystallization front shape during Czochralski growth of gadolinium gallium garnet crystal

    Science.gov (United States)

    Faiez, Reza; Rezaei, Yazdan

    2017-10-01

    Time-dependent, finite volume method calculations of momentum and heat transfer were carried out to investigate the correlation between oscillatory convection and the crystallization front dynamics during the Czochralski (Cz) growth of an oxide material. The present modeling allows us to illustrate the modification of the interface shape during the time period of oscillation of the flow manifesting as the formation of a cold plume beneath the phase boundary. It was shown that the instability mechanism is associated with an irreversible dramatic change in the interface shape, which occurs at a critical Reynolds number significantly lower than that is predicted by the quasi-stationary global model analysis of the Cz growth system. The baroclinic term which appears in the vorticity equation in a rotating stratified fluid is used to describe the numerical results of the model. The properties of the thermal waves were studied in the monitoring points located nearby the interface. The waves are regular but not in fact vertically correlated as observed in the case of baroclinic waves. The Rayleigh-Benard dynamics is suggested to be the predominant mechanism even though the instability is primarily baroclinic.

  18. Freeform Fabrication of Magnetophotonic Crystals with Diamond Lattices of Oxide and Metallic Glasses for Terahertz Wave Control by Micro Patterning Stereolithography and Low Temperature Sintering

    Directory of Open Access Journals (Sweden)

    Maasa Nakano

    2013-04-01

    Full Text Available Micrometer order magnetophotonic crystals with periodic arranged metallic glass and oxide glass composite materials were fabricated by stereolithographic method to reflect electromagnetic waves in terahertz frequency ranges through Bragg diffraction. In the fabrication process, the photo sensitive acrylic resin paste mixed with micrometer sized metallic glass of Fe72B14.4Si9.6Nb4 and oxide glass of B2O3·Bi2O3 particles was spread on a metal substrate, and cross sectional images of ultra violet ray were exposed. Through the layer by layer stacking, micro lattice structures with a diamond type periodic arrangement were successfully formed. The composite structures could be obtained through the dewaxing and sintering process with the lower temperature under the transition point of metallic glass. Transmission spectra of the terahertz waves through the magnetophotonic crystals were measured by using a terahertz time domain spectroscopy.

  19. Ionothermal synthesis of β-NH4AlF4 and the determination by single crystal X-ray diffraction of its room temperature and low temperature phases

    International Nuclear Information System (INIS)

    Parnham, Emily R.; Slawin, Alex M.Z.; Morris, Russell E.

    2007-01-01

    β-NH 4 AlF 4 has been synthesised ionothermally using 1-ethyl-3-methylimidazolium hexafluorophosphate as solvent and template provider. β-NH 4 AlF 4 crystals were produced which were suitable for single crystal X-ray diffraction analysis. A phase transition occurs between room temperature (298 K) and low temperature (93 K) data collections. At 298 K the space group=I4/mcm (no. 140), α=11.642(5), c=12.661(5) A, Z=2 (10NH 4 AlF 4 ), wR(F 2 )=0.1278, R(F)=0.0453. At 93 K the space group=P4 2 /ncm (no. 138), α=11.616(3), c=12.677(3) A, Z=2 (10NH 4 AlF 4 ), wR(F 2 )=0.1387, R(F)=0.0443. The single crystal X-ray diffraction study of β-NH 4 AlF 4 shows the presence of two different polymorphs at low and room temperature, indicative of a phase transition. The [AlF 4/2 F 2 ] - layers are undisturbed except for a small tilting of the AlF 6 octahedra in the c-axis direction. -Ionothermal synthesis, the use of an ionic liquid as the solvent in materials preparation, has been used to prepare β-NH 4 AlF 4 , and structural characterisation indicates that there are two versions of the structure, a low temperature primitive phase at 93 K and a high temperature body-centered phase at 298 K

  20. Dependence of the annealing kinetics of A centers and divacancies on temperature, particle energy, and irradiation dose for n-Si crystals

    International Nuclear Information System (INIS)

    Pagava, T.A.

    2002-01-01

    n-Si crystals grown by the float-zone method with a phosphorus concentration of ∼6 x 10 13 cm -3 and irradiated with 2-MeV electrons and 25-MeV protons were studied. It is shown that the kinetics of the isochronous annealing of the A centers and divacancies (the annealing temperature and the rearrangement of radiation defects in the situation where the dissociation of one type of defects gives rise to more stable defects) depends in a complicated way on the energy, dose, and temperature of irradiation; i.e., this kinetics depends on the relation between the concentrations of various radiation defects and on the charge state of reacting primary radiation defects when they interact with each other, with impurity atoms, and with disordered regions. An increase in the concentration of divacancies in the temperature range of 180-210 deg. C is attributed to the dissociation of disordered regions

  1. Effect of temperature on current voltage characteristics in ZnO/CdS/CuGaSe2 single crystal solar cells

    International Nuclear Information System (INIS)

    Saad, M.; Kassis, A.

    2005-03-01

    Current voltage characteristics of Zn O/CdS/CuGaSe 2 single crystal solar cells, which have gone through repetitive annealing treatment and have been measured at different values of temperature and illumination intensity, were analyzed using the two-diode equation. The analysis revealed that current transport in these cells is governed by two competing transport mechanisms relating strongly to interface states and that both mechanisms are thermally and light activated. These two mechanisms are interface recombination and tunneling enhanced interface recombination. The activation energy values of the saturation current density in both mechanisms were calculated from the temperature dependence of the parameters describing each of them. It was found that these values depend on temperature and illumination intensity. Furthermore, the behavior of the photovoltaic parameters could be explained relying on the results of the analysis. (Authors)

  2. Low-temperature radiation-induced polymerization of vinyl monomers in the crystal matrix of polydimethyl siloxane

    International Nuclear Information System (INIS)

    Mujdinov, M.R.; Kiryukhin, D.P.; Barkalov, I.M.; Gol'danskij, V.I.

    1979-01-01

    It is shown that in the process of the slow cooling of vinyl monomer solution in dimethyl siloxane rubber (SKT mark) crystallization of SKT takes place, at that, considerable part of vinyl monomers (up to 70 wt. % of rubber) is sorbed in the pores of crystal matrix and it does not form its proper crystal phase. Slight anomalies in heat capacity in the 120-140 K range, the melting of non-sorbed part of MA and the melting of SKT + MA ''complex'' have been observed on the calorimetric curve at the SKT - methylacrylate (MA) system heating. In the process of heating such samples, irradiated at 77 K by γ-rays of 60 Co, heat evolution connected with sorbed monomer polarization, has been observed starting from 125-130 K. In the 140-200 K range already before MA and SKT melting intense polymerization takes place, which results in practically full monomer consumption and formation of graft copolymer. Radiation-chemical yield of monomer reduction reaches G(-M) approximately equal to 2x10 5 molecules for 100 eV, radiation yield of postpolymerization of crystal MA does not exceed G(-M) approximately equal to 50 molecules for 100 eV

  3. Effect of Feed Melting, Temperature History, and Minor Component Addition on Spinel Crystallization in High-Level Waste Glass

    Czech Academy of Sciences Publication Activity Database

    Izák, Pavel; Hrma, P.; Arey, B. W.; Plaisted, T. J.

    2001-01-01

    Roč. 289, 1-3 (2001), s. 17-29 ISSN 0022-3093 Grant - others:DOE(US) DE/06/76RL01830 Keywords : feed melting * crystalization * high-level waste glass Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.363, year: 2001

  4. Crystallization of urea from an evaporative aqueous solution sessile droplet at sub-boiling temperatures and surfaces with different wettability

    NARCIS (Netherlands)

    Schmid, J.; Zarikos, I.; Terzis, A.; Roth, N.; Weigand, B.

    The injection of urea-water-solution sprays in the exhaust pipe of modern diesel engines eliminates NOx emissions in a very great extent. However, as water evaporates from the solution, urea is crystallized and causes walldeposit formations hindering the performance of selective-catalytic-reaction.

  5. Orientation and Temperature Dependence of Piezoelectric Properties for Sillenite-Type Bi12TiO20 and Bi12SiO20 Single Crystals

    Directory of Open Access Journals (Sweden)

    Chuanying Shen

    2014-06-01

    Full Text Available The full matrix of electro-elastic constants of sillenite-type crystals Bi12TiO20 (BTO and Bi12SiO20 (BSO were determined by the resonance method, with d14 and k14 being on the order of 40–48 pC/N and 31%–36%, respectively. In addition, double-rotated orientation dependence of d33 was investigated, with the maximum values of 25–28 pC/N being achieved in ZXtl45°/54°-cut samples. The electrical resistivity of BSO was found to be two orders higher than that of BTO, being on the order of 7 × 105 Ω cm at 500 °C. The temperature dependence of dielectric and piezoelectric properties were investigated. BSO exhibited a high thermal stability in the temperature range of 25–500 °C, while BTO showed a variation of ~3% in the range of 25–350 °C. The high values of d14 and k14, together with the good thermal stability, make BTO and BSO crystals potential candidates for electromechanical applications in medium temperature range.

  6. Development of re-crystallized W-1.1%TiC with enhanced room-temperature ductility and radiation performance

    International Nuclear Information System (INIS)

    Kurishita, H.; Matsuo, S.; Arakawa, H.; Sakamoto, T.; Kobayashi, S.; Nakai, K.; Takida, T.; Kato, M.; Kawai, M.; Yoshida, N.

    2010-01-01

    Ultra-fine grained (UFG) W-TiC compacts fabricated by powder metallurgical methods utilizing mechanical alloying (MA) are very promising for use in irradiation environments. However, the assurance of room-temperature ductility and enhancement in surface resistances to low-energy hydrogen irradiation are unsettled issues. As an approach to solution to these, microstructural modification by hot plastic working has been applied to UFG W-TiC processed by MA in a purified Ar or H 2 atmosphere and hot isostatic pressing (HIP). Hot plastically worked compacts have been subjected to 3-point bend tests at room temperature and TEM microstructural examinations. It is found that the microstructural modification allows us to convert UFG W-1.1%TiC to compacts exhibiting a very high fracture strength and appreciable ductility at room temperature. The compacts of W-1.1%TiC/Ar (MA atmosphere: Ar) and W-1.1%TiC/H 2 (MA atmosphere: H 2 ) exhibit re-crystallized structures with approximately 0.5 and 1.5 μm in grain size, respectively. It is shown that the enhancement of fracture resistance by microstructural modifications is attributed to significant strengthening of weak grain boundaries in the re-crystallized state. As a result the modified compacts exhibit superior surface resistance to low-energy deuteron irradiation.

  7. Development of re-crystallized W-1.1%TiC with enhanced room-temperature ductility and radiation performance

    Energy Technology Data Exchange (ETDEWEB)

    Kurishita, H., E-mail: kurishi@imr.tohoku.ac.j [International Research Center for Nuclear Materials Science, IMR, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Matsuo, S.; Arakawa, H. [International Research Center for Nuclear Materials Science, IMR, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Sakamoto, T.; Kobayashi, S.; Nakai, K. [Department of Materials Science and Biotechnology, Ehime University, Matsuyama 790-8577 (Japan); Takida, T.; Kato, M. [A.L.M.T. Corp., Toyama 931-8543 (Japan); Kawai, M. [Institute of Material Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan); Yoshida, N. [Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan)

    2010-03-15

    Ultra-fine grained (UFG) W-TiC compacts fabricated by powder metallurgical methods utilizing mechanical alloying (MA) are very promising for use in irradiation environments. However, the assurance of room-temperature ductility and enhancement in surface resistances to low-energy hydrogen irradiation are unsettled issues. As an approach to solution to these, microstructural modification by hot plastic working has been applied to UFG W-TiC processed by MA in a purified Ar or H{sub 2} atmosphere and hot isostatic pressing (HIP). Hot plastically worked compacts have been subjected to 3-point bend tests at room temperature and TEM microstructural examinations. It is found that the microstructural modification allows us to convert UFG W-1.1%TiC to compacts exhibiting a very high fracture strength and appreciable ductility at room temperature. The compacts of W-1.1%TiC/Ar (MA atmosphere: Ar) and W-1.1%TiC/H{sub 2} (MA atmosphere: H{sub 2}) exhibit re-crystallized structures with approximately 0.5 and 1.5 mum in grain size, respectively. It is shown that the enhancement of fracture resistance by microstructural modifications is attributed to significant strengthening of weak grain boundaries in the re-crystallized state. As a result the modified compacts exhibit superior surface resistance to low-energy deuteron irradiation.

  8. Non-linear thermal evolution of the crystal structure and phase transitions of LaFeO3 investigated by high temperature X-ray diffraction

    International Nuclear Information System (INIS)

    Selbach, Sverre M.; Tolchard, Julian R.; Fossdal, Anita; Grande, Tor

    2012-01-01

    The crystal structure, anisotropic thermal expansion and structural phase transition of the perovskite LaFeO 3 has been studied by high-temperature X-ray diffraction from room temperature to 1533 K. The structural evolution of the orthorhombic phase with space group Pbnm and the rhombohedral phase with R3 ¯ c structure of LaFeO 3 is reported in terms of lattice parameters, thermal expansion coefficients, atomic positions, octahedral rotations and polyhedral volumes. Non-linear lattice expansion across the antiferromagnetic to paramagnetic transition of LaFeO 3 at T N =735 K was compared to the corresponding behavior of the ferroelectric antiferromagnet BiFeO 3 to gain insight to the magnetoelectric coupling in BiFeO 3 , which is also multiferroic. The first order phase transition of LaFeO 3 from Pbnm to R3 ¯ c was observed at 1228±9 K, and a subsequent transition to Pm3 ¯ m was extrapolated to occur at 2140±30 K. The stability of the Pbnm and R3 ¯ c polymorphs of LaFeO 3 is discussed in terms of the competing enthalpy and entropy of the two crystal polymorphs and the thermal evolution of the polyhedral volume ratio V A /V B . - Graphical abstract: Aniostropic thermal evolution of the lattice parameters and phase transition of LaFeO 3 . Highlights: ► The crystal structure of LaFeO 3 is studied by HTXRD from RT to 1533 K. ► A non-linear expansion across the Néel temperature is observed for LaFeO 3 . ► The ratio V A /V B is used to rationalize the thermal evolution of the structure.

  9. Oxygen vacancy-induced room-temperature ferromagnetism in D—D neutron irradiated single-crystal TiO2 (001) rutile

    Science.gov (United States)

    Xu, Nan-Nan; Li, Gong-Ping; Pan, Xiao-Dong; Wang, Yun-Bo; Chen, Jing-Sheng; Bao, Liang-Man

    2014-10-01

    Remarkable room temperature ferromagnetism in pure single-crystal rutile TiO2 (001) samples irradiated by D—D neutron has been investigated. By combining X-ray diffraction and positron annihilation lifetime, the contracted lattice has been clearly identified in irradiated TiO2, where Ti4+ ions can be easily reduced to the state of Ti3+. As there were no magnetic impurities that could contaminate the samples during the whole procedure, some Ti3+ ions reside on interstitial or substituted sites accompanied by oxygen vacancies should be responsible for the ferromagnetism.

  10. Measurement of core plasma temperature and rotation on W7-X made available by the x-ray imaging crystal spectrometer (XICS)

    Energy Technology Data Exchange (ETDEWEB)

    Pablant, N A; Bitter, M; Burhenn, R; Delgado-Aparicio, L; Ellis, R; Gates, D; Goto, M; Hill, K W; Langenberg, A; Lazerson, S; Mardenfeld, M; Morita, S; Neilson, G H; Oishi, T; Pedersen, T S

    2014-07-01

    A new x-ray imaging crystal spectrometer diagnostic (XICS) is currently being built for installation on W7-X. This diagnostic will contribute to the study of ion and electron thermal transport and the evolution of the radial electric field by providing high resolution temperature and rotation measurements under many plasma conditions, including ECH heated plasmas. Installation is expected before the first experimental campaign (OP1.1), making an important set of measurements available for the first W7-X plasmas. This diagnostic will also work in concert with the HR-XCS diagnostic to provide an excellent diagnostic set for core impurity transport on W7-X.

  11. Low temperature rf sputtering deposition of (Ba, Sr) TiO3 thin film with crystallization enhancement by rf power supplied to the substrate

    International Nuclear Information System (INIS)

    Yoshimaru, Masaki; Takehiro, Shinobu; Abe, Kazuhide; Onoda, Hiroshi

    2005-01-01

    The (Ba, Sr) TiO 3 thin film deposited by radio frequency (rf) sputtering requires a high deposition temperature near 500 deg. C to realize a high relative dielectric constant over of 300. For example, the film deposited at 330 deg. C contains an amorphous phase and shows a low relative dielectric constant of less than 100. We found that rf power supplied not only to the (Ba, Sr) TiO 3 sputtering target, but also to the substrate during the initial step of film deposition, enhanced the crystallization of the (Ba, Sr) TiO 3 film drastically and realized a high dielectric constant of the film even at low deposition temperatures near 300 deg. C. The 50-nm-thick film with only a 10 nm initial layer deposited with the substrate rf biasing is crystallized completely and shows a high relative dielectric constant of 380 at the deposition temperature of 330 deg. C. The (Ba, Sr) TiO 3 film deposited at higher temperatures (upwards of 400 deg. C) shows preferred orientation, while the film deposited at 330 deg. C with the 10 nm initial layer shows a preferred orientation on a -oriented ruthenium electrode. The unit cell of (Ba, Sr) TiO 3 (111) plane is similar to that of ruthenium (001) plane. We conclude that the rf power supplied to the substrate causes ion bombardments on the (Ba, Sr) TiO 3 film surface, which assists the quasiepitaxial growth of (Ba, Sr) TiO 3 film on the ruthenium electrode at low temperatures of less than 400 deg. C

  12. Low temperature rf sputtering deposition of (Ba, Sr) TiO3 thin film with crystallization enhancement by rf power supplied to the substrate

    Science.gov (United States)

    Yoshimaru, Masaki; Takehiro, Shinobu; Abe, Kazuhide; Onoda, Hiroshi

    2005-05-01

    The (Ba, Sr) TiO3 thin film deposited by radio frequency (rf) sputtering requires a high deposition temperature near 500 °C to realize a high relative dielectric constant over of 300. For example, the film deposited at 330 °C contains an amorphous phase and shows a low relative dielectric constant of less than 100. We found that rf power supplied not only to the (Ba, Sr) TiO3 sputtering target, but also to the substrate during the initial step of film deposition, enhanced the crystallization of the (Ba, Sr) TiO3 film drastically and realized a high dielectric constant of the film even at low deposition temperatures near 300 °C. The 50-nm-thick film with only a 10 nm initial layer deposited with the substrate rf biasing is crystallized completely and shows a high relative dielectric constant of 380 at the deposition temperature of 330 °C. The (Ba, Sr) TiO3 film deposited at higher temperatures (upwards of 400 °C) shows preferred orientation, while the film deposited at 330 °C with the 10 nm initial layer shows a preferred orientation on a -oriented ruthenium electrode. The unit cell of (Ba, Sr) TiO3 (111) plane is similar to that of ruthenium (001) plane. We conclude that the rf power supplied to the substrate causes ion bombardments on the (Ba, Sr) TiO3 film surface, which assists the quasiepitaxial growth of (Ba, Sr) TiO3 film on the ruthenium electrode at low temperatures of less than 400 °C.

  13. Optical bleaching of F-centers in BaFCl crystals after X-irradiation at room temperature

    International Nuclear Information System (INIS)

    Inabe, K.; Nakamura, S.; Takeuchi, N.

    1988-01-01

    The optical bleaching behaviour of the F-band formed by X-irradiation in BaFCl crystals is investigated paying attention to the difference between two types of F-centers. Optical absorption spectra, decay curves of the F-band under excitation with F light and excitation spectra of the bleaching are given and discussed. The bleaching of the F-bands is achieved by light in the absorption band irrespective of the component. Energy transfer among excited states of F-centers is responsible for the bleaching of F-centers in BaFCl crystals, involving energy transfer between F(Cl - ) and F(F - ) centers in their optical bleaching process

  14. Praseodymium Cuprate Thin Film Cathodes for Intermediate Temperature Solid Oxide Fuel Cells: Roles of Doping, Orientation, and Crystal Structure.

    Science.gov (United States)

    Mukherjee, Kunal; Hayamizu, Yoshiaki; Kim, Chang Sub; Kolchina, Liudmila M; Mazo, Galina N; Istomin, Sergey Ya; Bishop, Sean R; Tuller, Harry L

    2016-12-21

    Highly textured thin films of undoped, Ce-doped, and Sr-doped Pr 2 CuO 4 were synthesized on single crystal YSZ substrates using pulsed laser deposition to investigate their area-specific resistance (ASR) as cathodes in solid-oxide fuel cells (SOFCs). The effects of T' and T* crystal structures, donor and acceptor doping, and a-axis and c-axis orientation on ASR were systematically studied using electrochemical impedance spectroscopy on half cells. The addition of both Ce and Sr dopants resulted in improvements in ASR in c-axis oriented films, as did the T* crystal structure with the a-axis orientation. Pr 1.6 Sr 0.4 CuO 4 is identified as a potential cathode material with nearly an order of magnitude faster oxygen reduction reaction kinetics at 600 °C compared to thin films of the commonly studied cathode material La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ . Orientation control of the cuprate films on YSZ was achieved using seed layers, and the anisotropy in the ASR was found to be less than an order of magnitude. The rare-earth doped cuprate was found to be a versatile system for study of relationships between bulk properties and the oxygen reduction reaction, critical for improving SOFC performance.

  15. Accuracy of pulse oximetry in detection of oxygen saturation in patients admitted to the intensive care unit of heart surgery: comparison of finger, toe, forehead and earlobe probes.

    Science.gov (United States)

    Seifi, Sohila; Khatony, Alireza; Moradi, Gholamreza; Abdi, Alireza; Najafi, Farid

    2018-01-01

    Heart surgery patients are more at risk of poor peripheral perfusion, and peripheral capillary oxygen saturation (SpO2) measurement is regular care for continuous analysis of blood oxygen saturation in these patients. With regard to controversial studies on accuracy of the current pulse oximetry probes and lack of data related to patients undergoing heart surgery, the present study was conducted to determine accuracy of pulse oximetry probes of finger, toe, forehead and earlobe in detection of oxygen saturation in patients admitted to intensive care units for coronary artery bypass surgery. In this clinical trial, 67 patients were recruited based on convenience sampling method among those admitted to intensive care units for coronary artery bypass surgery. The SpO2 value was measured using finger, toe, forehead and earlobe probes and then compared with the standard value of arterial oxygen saturation (SaO2). Data were entered into STATA-11 software and analyzed using descriptive, inferential and Bland-Altman statistical analyses. Highest and lowest correlational mean values of SpO2 and SaO2 were related to finger and earlobe probes, respectively. The highest and lowest agreement of SpO2 and SaO2 were related to forehead and earlobe probes. The SpO2 of earlobe probes due to lesser mean difference, more limited confidence level and higher agreement ration with SaO2 resulted by arterial blood gas (ABG) analysis had higher accuracy. Thus, it is suggested to use earlobe probes in patients admitted to the intensive care unit for coronary artery bypass surgery. Registration of this trial protocol has been approved in Iranian Registry of Clinical Trials at 2018-03-19 with reference IRCT20100913004736N22. "Retrospectively registered."

  16. A compounded rare-earth iron garnet single crystal exhibiting stable Faraday rotation against wavelength and temperature variation in the 1.55 μm band

    International Nuclear Information System (INIS)

    Xu, Z.C.; Huang, M.; Li Miao

    2006-01-01

    The Bi, Tb and Yb partially substituted iron garnet bulk single crystals of Tb 3- x - y Yb y Bi x Fe 5 O 12 were grown by using Bi 2 O 3 /B 2 O 3 as flux and accelerated crucible rotation technique for single-crystal growth. Faraday rotation (FR) spectra showed that the specific FR of the (Tb 0.91 Yb 1.38 Bi 0.71 )Fe 5 O 12 crystal under magnetic field at saturation was measured to be about -1617 o /cm at λ=1.55 μm, Faraday rotation wavelength coefficient (FWC, 0.009%/nm) in the wavelength range of 1.50-1.62 μm and Faraday rotation temperature coefficient (FTC, 3.92x10 -5 /K) at λ=1.55 μm were even smaller than that of YIG. It is proven that through combining two types of Bi-substituted rare-earth iron garnets with opposite FWC and FTC signs, the compound rare-earth iron garnets with low FWC and FTC may be obtained due to the compensation effect. The saturation magnetization of (Tb 0.91 Yb 1.38 Bi 0.71 ) Fe 5 O 12 crystal is 0.48x10 6 A/M and is also much smaller than that of YIG. We have found empirically that there is a simple relationship between the FR θ f (x) and Bi content x for Tb 3- x - y Yb y Bi x Fe 5 O 12 , which is given by θ f (x)=(-2759x+400) o /cm

  17. Variable-temperature single-crystal X-ray diffraction study of tetragonal and cubic perovskite-type barium titanate phases.

    Science.gov (United States)

    Nakatani, Tomotaka; Yoshiasa, Akira; Nakatsuka, Akihiko; Hiratoko, Tatsuya; Mashimo, Tsutomu; Okube, Maki; Sasaki, Satoshi

    2016-02-01

    A variable-temperature single-crystal X-ray diffraction study of a synthetic BaTiO3 perovskite has been performed over the temperature range 298-778 K. A transition from a tetragonal (P4mm) to a cubic (Pm3m) phase has been revealed near 413 K. In the non-centrosymmetric P4mm symmetry group, both Ti and O atoms are displaced along the c-axis in opposite directions with regard to the Ba position fixed at the origin, so that Ti(4+) and Ba(2+) cations occupy off-center positions in the TiO6 and BaO12 polyhedra, respectively. Smooth temperature-dependent changes of the atomic coordinates become discontinuous with the phase transition. Our observations imply that the cations remain off-center even in the high-temperature cubic phase. The temperature dependence of the mean-square displacements of Ti in the cubic phase includes a significant static component which means that Ti atoms are statistically distributed in the off-center positions.

  18. High-Q energy trapping of temperature-stable shear waves with Lamé cross-sectional polarization in a single crystal silicon waveguide

    Science.gov (United States)

    Tabrizian, R.; Daruwalla, A.; Ayazi, F.

    2016-03-01

    A multi-port electrostatically driven silicon acoustic cavity is implemented that efficiently traps the energy of a temperature-stable eigen-mode with Lamé cross-sectional polarization. Dispersive behavior of propagating and evanescent guided waves in a ⟨100⟩-aligned single crystal silicon waveguide is used to engineer the acoustic energy distribution of a specific shear eigen-mode that is well known for its low temperature sensitivity when implemented in doped single crystal silicon. Such an acoustic energy trapping in the central region of the acoustic cavity geometry and far from substrate obviates the need for narrow tethers that are conventionally used for non-destructive and high quality factor (Q) energy suspension in MEMS resonators; therefore, the acoustically engineered waveguide can simultaneously serve as in-situ self-oven by passing large uniformly distributed DC currents through its body and without any concern about perturbing the mode shape or deforming narrow supports. Such a stable thermo-structural performance besides large turnover temperatures than can be realized in Lamé eigen-modes make this device suitable for implementation of ultra-stable oven-controlled oscillators. 78 MHz prototypes implemented in arsenic-doped single crystal silicon substrates with different resistivity are transduced by in- and out-of-plane narrow-gap capacitive ports, showing high Q of ˜43k. The low resistivity device shows an overall temperature-induced frequency drift of 200 ppm over the range of -20 °C to 80 °C, which is ˜15× smaller compared to overall frequency drift measured for the similar yet high resistivity device in the same temperature range. Furthermore, a frequency tuning of ˜2100 ppm is achieved in high resistivity device by passing 45 mA DC current through its body. Continuous operation of the device under such a self-ovenizing current over 10 days did not induce frequency instability or degradation in Q.

  19. Measurement of temperature and concentration influence on the dispersion of fused silica glass photonic crystal fiber infiltrated with water-ethanol mixture

    Science.gov (United States)

    Van, Hieu Le; Buczynski, Ryszard; Long, Van Cao; Trippenbach, Marek; Borzycki, Krzysztof; Manh, An Nguyen; Kasztelanic, Rafal

    2018-01-01

    We present experimental and simulation results of the zero-dispersion shift in photonics crystal fibers infiltrated with water-ethanol mixture. The fiber based on the fused silica glass with a hexagonal lattice consists of seven rings of air-holes filled by liquid. We show that it is possible to shift the zero-dispersion wavelength by 35 ps/nm/km when changing the temperature by 60 °C, and by 42 ps/nm/km when changing the concentration of ethanol from 0 to 100%. The results also show that for the optical fiber filed with pure ethanol the flattened part of the dispersion shifts from anomalous to the normal regime at temperatures below -70 °C.

  20. Modification of UO2 grain re-crystallization temperature in function of burn-up as a base for Vitanza experimental curve reconstruction

    International Nuclear Information System (INIS)

    Szuta, M.; Dąbrowski, L.

    2013-01-01

    Crossing the experimental critical fuel temperature dependent on burn-up, an onset of fission gas burst release is observed. This observed phenomena can be explained by assumption that the fission gas immobilization in the uranium dioxide irradiated to a fluency of greater than 10 19 fissions/cm 3 is mainly due to radiation induced chemical activity. Application of the “ab initio” method show that the bond energy of Xenon and Krypton is equal to –1.23 eV, and –3.42 eV respectively. Assuming further that the gas chemically bound can be released mainly in the process of re-crystallization and modifying the differential equation of Ainscough of grain growth by including the burn-up dependence and the experimental data of limiting grain size in function of the fuel temperature for the un-irradiated and irradiated fuel we can re-construct the experimental curve of Vitanza. (authors)

  1. Dynamic phase transition in the kinetic spin-32 Blume-Capel model: Phase diagrams in the temperature and crystal-field interaction plane

    International Nuclear Information System (INIS)

    Keskin, Mustafa; Canko, Osman; Deviren, Bayram

    2007-01-01

    We analyze, within a mean-field approach, the stationary states of the kinetic spin-32 Blume-Capel (BC) model by the Glauber-type stochastic dynamics and subject to a time-dependent oscillating external magnetic field. The dynamic phase transition (DPT) points are obtained by investigating the behavior of the dynamic magnetization as a function of temperature and as well as calculating the Liapunov exponent. Phase diagrams are constructed in the temperature and crystal-field interaction plane. We find five fundamental types of phase diagrams for the different values of the reduced magnetic field amplitude parameter (h) in which they present a disordered, two ordered phases and the coexistences phase regions. The phase diagrams also exhibit a dynamic double-critical end point for 0 5.06

  2. Dynamic phase transition in the kinetic spin-1 Blume-Capel model: Phase diagrams in the temperature and crystal-field interaction plane

    International Nuclear Information System (INIS)

    Keskin, M.; Canko, O.; Temizer, U.

    2007-01-01

    Within a mean-field approach, the stationary states of the kinetic spin-1 Blume-Capel model in the presence of a time-dependent oscillating external magnetic field is studied. The Glauber-type stochastic dynamics is used to describe the time evolution of the system and obtain the mean-field dynamic equation of motion. The dynamic phase-transition points are calculated and phase diagrams are presented in the temperature and crystal-field interaction plane. According to the values of the magnetic field amplitude, three fundamental types of phase diagrams are found: One exhibits a dynamic tricritical point, while the other two exhibit a dynamic zero-temperature critical point

  3. Dynamic phase transition in the kinetic spin-32 Blume-Capel model: Phase diagrams in the temperature and crystal-field interaction plane

    Energy Technology Data Exchange (ETDEWEB)

    Keskin, Mustafa [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)]. E-mail: keskin@erciyes.edu.tr; Canko, Osman [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Deviren, Bayram [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)

    2007-06-15

    We analyze, within a mean-field approach, the stationary states of the kinetic spin-32 Blume-Capel (BC) model by the Glauber-type stochastic dynamics and subject to a time-dependent oscillating external magnetic field. The dynamic phase transition (DPT) points are obtained by investigating the behavior of the dynamic magnetization as a function of temperature and as well as calculating the Liapunov exponent. Phase diagrams are constructed in the temperature and crystal-field interaction plane. We find five fundamental types of phase diagrams for the different values of the reduced magnetic field amplitude parameter (h) in which they present a disordered, two ordered phases and the coexistences phase regions. The phase diagrams also exhibit a dynamic double-critical end point for 05.06.

  4. Development of a High Resolution X-Ray Imaging Crystal Spectrometer for Measurement of Ion-Temperature and Rotation-Velocity Profiles in Fusion Energy Research Plasmas

    International Nuclear Information System (INIS)

    Hill, K.W.; Bitter, M.L.; Broennimann, Ch.; Eikenberry, E.F.; Ince-Cushman, A.; Lee, S.G.; Rice, J.E.; Scott, S.; Barnsley, R.

    2008-01-01

    A new imaging high resolution x-ray crystal spectrometer (XCS) has been developed to measure continuous profiles of ion temperature and rotation velocity in fusion plasmas. Following proof-of-principle tests on the Alcator C-Mod tokamak and the NSTX spherical tokamak, and successful testing of a new silicon, pixilated detector with 1MHz count rate capability per pixel, an imaging XCS is being designed to measure full profiles of T i and ν φ on C-Mod. The imaging XCS design has also been adopted for ITER. Ion-temperature uncertainty and minimum measurable rotation velocity are calculated for the C-Mod spectrometer. The affects of x-ray and nuclear-radiation background on the measurement uncertainties are calculated to predict performance on ITER

  5. High-temperature crystallization of the secondary alcohol dehydrogenase from the extreme thermophilic bacteria Thermoanaerobacter ethanolicus, a bifunctional alcohol dehydrogenase-acetyl-CoA thio esterase

    International Nuclear Information System (INIS)

    Watanabe, L.; Arni, R.K.

    1996-01-01

    Full text. Ethanol fermentations from Saccharomyces sp. are used in industrial ethanol production and are performed at mesophilic temperatures where final ethanol concentrations must exceed 4% (v/v) to make the process industrially economic. In addition, distillation is required to recover ethanol. Thermophilic fermentations are very attractive since they enable separation of ethanol from continuous cultures at process temperature and reduced pressure. Two different ethanol-production pathways have been identified for thermophilic bacteria; type I from Clostridium thermocellum, which contains only NADH-linked primary-alcohol dehydrogeneases, and type II from Thermoanaerobacter brockii which in addition include NADPH-linked secondary-alcohol dehydrogenases. The thermophilic anaerobic bacterium T ethanolicus 39E produces ethanol as the major end product from starch, pentose and herose substrates. The 2 Adh has a lower catalytic efficiency for the oxidation of 1 alcohols, including ethanol, than for the oxidation of secondary (2) alcohols or the reduction of ketones or aldehydes and possesses a significant acetyl-CoA reductive thioesterase activity. Large single crystals (0.7 x 0.3 x 0.3 mn) of this enzyme have been obtained at 40 0 C and diffraction data to 2.7 A resolution has been collected (R merge = 10.44%). Attempts are currently underway to obtain higher resolution data and a search for heavy atom derivatives is currently underway. The crystals belong to the space group P2 1 2 1 2 with cell constants of a a= 170.0 A, b=125.7 A and c=80.5 A. The asymmetric unit contains a tetramer as in the case of the crystals of the secondary alcohol dehydrogenase from Thermoanaerobacter brockii with a V M of 2.85 A 3 /Da. (author)

  6. Structural and elastic anisotropy of crystals at high pressures and temperatures from quantum mechanical methods: The case of Mg{sub 2}SiO{sub 4} forsterite

    Energy Technology Data Exchange (ETDEWEB)

    Erba, A., E-mail: alessandro.erba@unito.it; Dovesi, R. [Dipartimento di Chimica and Centre of Excellence NIS (Nanostructured Interfaces and Surfaces), Università di Torino, via Giuria 5, IT-10125 Torino (Italy); Maul, J. [Dipartimento di Chimica and Centre of Excellence NIS (Nanostructured Interfaces and Surfaces), Università di Torino, via Giuria 5, IT-10125 Torino (Italy); Laboratório de Combustíveis e Materiais, INCTMN-UFPB, Universidade Federal da Paraíba, CEP 58051-900 João Pessoa, PB (Brazil); De La Pierre, M. [Nanochemistry Research Institute, Curtin Institute for Computation, Department of Chemistry, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia)

    2015-05-28

    We report accurate ab initio theoretical predictions of the elastic, seismic, and structural anisotropy of the orthorhombic Mg{sub 2}SiO{sub 4} forsterite crystal at high pressures (up to 20 GPa) and temperatures (up to its melting point, 2163 K), which constitute earth’s upper mantle conditions. Single-crystal elastic stiffness constants are evaluated up to 20 GPa and their first- and second-order pressure derivatives reported. Christoffel’s equation is solved at several pressures: directional seismic wave velocities and related properties (azimuthal and polarization seismic anisotropies) discussed. Thermal structural and average elastic properties, as computed within the quasi-harmonic approximation of the lattice potential, are predicted at high pressures and temperatures: directional thermal expansion coefficients, first- and second-order pressure derivatives of the isothermal bulk modulus, and P-V-T equation-of-state. The effect on computed properties of five different functionals, belonging to three different classes of approximations, of the density functional theory is explicitly investigated.

  7. Phase Separation and Crystallization in soda-lime borosilicate glass enriched in MoO{sub 3} studied by in situ Raman spectroscopy at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Magnin, M.; Schuller, S.; Advocat, T. [CEA Valrho, DEN/DTCD/SCDV, Laboratoire d' Etude de Base sur les Verres, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France); Caurant, D.; Majerus, O. [Laboratoire de Chimie de la Matiere Condensee de Paris- LCMCP - UMR-CNRS 7574, Ecole Nationale Superieure de Chimie de Paris - ENSCP, Paristech, 75231 Paris (France); Ligny, D. de [Laboratoire de Physico-Chimie des Materiaux Luminescents- LPCML - UMR-CNRS 5620, Universite Claude Bernard Lyon1, 69622 Villeurbanne (France)

    2008-07-01

    Phase separation and crystallisation processes may arise in molten glass when the MoO{sub 3} content exceeds its solubility limit. Molybdenum combined with other elements such as alkali and alkaline-earth may form crystalline molybdates, known as 'yellow phases' in nuclear glasses. In order to establish the sequence of phase separation and crystallization processes occurring during the cooling of the melt, a non-radioactive simplified glass composition was chosen in the SiO{sub 2}-B{sub 2}O{sub 3}-Na{sub 2}O-CaO system, with 2 mol.% MoO{sub 3}. Various cooling scenarios were tested: cooling by air blowing, quenching between two copper plates and cooling on metallic plate. The resulting glass specimens were then characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy in temperature. These observations made it possible to determine the sequence and the appearance temperature of phenomena upon cooling: first, a phase separation occurs, (small droplets dispersed in the molten glass) followed by molybdates crystallization inside the droplets. (authors)

  8. A combined temperature-dependent electron and single-crystal X-ray diffraction study of the fresnoite compound Rb2V4+V25+O8

    International Nuclear Information System (INIS)

    Withers, R.L.; Hoeche, Thomas; Liu Yun; Esmaeilzadeh, Saeid; Keding, Ralf; Sales, Brian

    2004-01-01

    High-purity Rb 2 V 3 O 8 has been grown and temperature-dependent electron and single-crystal X-ray diffraction used to carefully investigate its fresnoite-type reciprocal lattice. In contrast to other recently investigated representatives of the fresnoite family of compounds, Rb 2 V 3 O 8 is not incommensurately modulated with an incommensurate basal plane primary modulation wave vector given by q∼0.3 *. A careful low-temperature electron diffraction study has, however, revealed the existence of weak incommensurate satellite reflections characterized by the primitive primary modulation wave vector q 1 ∼0.16c*. The reciprocal space positioning of these incommensurate satellite reflections, the overall (3+1)-d superspace group symmetry, as well as the shapes of the refined displacement ellipsoids determined from single-crystal XRD refinement, are all consistent with their arising from a distinct type of condensed rigid unit modes (RUMs) of distortion of the Rb 2 V 3 O 8 parent structure

  9. Low temperature time resolved photoluminescence in ordered and disordered Cu{sub 2}ZnSnS{sub 4} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Raadik, Taavi, E-mail: taavi.raadik@ttu.ee [Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Krustok, Jüri; Kauk-Kuusik, M.; Timmo, K.; Grossberg, M. [Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Ernits, K. [crystalsol OÜ, Akadeemia tee 15a, 12618 Tallinn (Estonia); Bleuse, J. [CEA-CNRS-UGA group “Nanophysique et Semiconducteurs”, Univ. Grenoble Alpes, INAC-PHELIQS, CEA, INAC-PHELIQS, CNRS, PLUM, F-38000 Grenoble (France)

    2017-03-01

    In this work we performed time-resolved micro-photoluminescence (TRPL) studies of Cu{sub 2}ZnSnS{sub 4} (CZTS) single crystals grown in molten KI salt. The order/disorder degree of CZTS was varied by the thermal post treatment temperature. Photoluminescence spectra measured at T=8 K showed an asymmetric band with a peak position of 1.33 eV and 1.27 eV for partially ordered and disordered structures, respectively. Thermal activation energies were found to be E{sub T} {sub (PO)} =65±9 meV for partially ordered and E{sub T(PD)} =27±4 meV for partially disordered. These low activation energy values indicating to the defect cluster recombination model for both partially ordered and disordered structures. TRPL was measured for both crystals and their decay curves were fitted with a stretched exponential function, in order to describe the charge carriers’ recombination dynamics at low temperature.

  10. Temperature dependence of the magnetic anisotropy of metallic Y-Ba-Cu-O single crystals in the normal phase

    International Nuclear Information System (INIS)

    Miljak, M.; Zlatic, V.; Kos, I.; Aviani, I.; Hamzic, A.; Collin, G.

    1990-01-01

    The magnetic anisotropy measurements of metallic Y-Ba-Cu-O compounds in the normal phase reveal a temperature-dependent diamagnetic component of the susceptibility that increases with decreasing temperature. The temperature variation of the susceptibility anisotropy and its total change do not seem to be much affected by the presence of the superconductivity at some lower temperature and could not be accounted for by superconducting fluctuations. Rather, the data remind one of the behavior of some quasi-two-dimensional metals with anisotropic Fermi surfaces, reflecting the properties of the low-energy excitations in the normal phase. The anisotropy measurements above the bulk superconducting transition temperature T c reveal the nonlinear effects, which are due to the onset of superconductivity in disconnected grains. The existence of a two-step transition, typical for granular superconductors, should be taken into consideration if the normal-phase susceptibility data are compared with the theoretical predictions in the vicinity of T c

  11. Topology and temperature dependence of the diffuse X-ray scattering in Na0.5Bi0.5TiO3 ferroelectric single crystals.

    Science.gov (United States)

    Gorfman, Semën; Keeble, Dean S; Bombardi, Alessandro; Thomas, Pam A

    2015-10-01

    The results of high-resolution measurements of the diffuse X-ray scattering produced by a perovskite-based Na 0.5 Bi 0.5 TiO 3 ferroelectric single crystal between 40 and 620 K are reported. The study was designed as an attempt to resolve numerous controversies regarding the average structure of Na 0.5 Bi 0.5 TiO 3 , such as the mechanism of the phase transitions between the tetragonal, P 4 bm , and rhombohedral | monoclinic, R 3 c  |  Cc , space groups and the correlation between structural changes and macroscopic physical properties. The starting point was to search for any transformations of structural disorder in the temperature range of thermal depoling (420-480 K), where the average structure is known to remain unchanged. The intensity distribution around the {032} pseudocubic reflection was collected using a PILATUS 100K detector at the I16 beamline of the Diamond Light Source (UK). The data revealed previously unknown features of the diffuse scattering, including a system of dual asymmetric L-shaped diffuse scattering streaks. The topology, temperature dependence, and relationship between Bragg and diffuse intensities suggest the presence of complex microstructure in the low-temperature R 3 c  |  Cc phase. This microstructure may be formed by the persistence of the higher-temperature P 4 bm phase, built into a lower-temperature R 3 c  |  Cc matrix, accompanied by the related long-range strain fields. Finally, it is shown that a correlation between the temperature dependence of the X-ray scattering features and the temperature regime of thermal depoling is present.

  12. Temperature-dependent Raman spectroscopy studies of the interface coupling effect of monolayer ReSe2 single crystals on Au foils

    Science.gov (United States)

    Jiang, Shaolong; Zhao, Liyun; Shi, Yuping; Xie, Chunyu; Zhang, Na; Zhang, Zhepeng; Huan, Yahuan; Yang, Pengfei; Hong, Min; Zhou, Xiebo; Shi, Jianping; Zhang, Qing; Zhang, Yanfeng

    2018-05-01

    Rhenium diselenide (ReSe2), which bears in-plane anisotropic optical and electrical properties, is of considerable interest for its excellent applications in novel devices, such as polarization-sensitive photodetectors and integrated polarization-controllers. However, great challenges to date in the controllable synthesis of high-quality ReSe2 have hindered its in-depth investigations and practical applications. Herein, we report a feasible synthesis of monolayer single-crystal ReSe2 flakes on the Au foil substrate by using a chemical vapor deposition route. Particularly, we focus on the temperature-dependent Raman spectroscopy investigations of monolayer ReSe2 grown on Au foils, which present concurrent red shifts of Eg-like and Ag-like modes with increasing measurement temperature from 77–290 K. Linear temperature dependences of both modes are revealed and explained from the anharmonic vibration of the ReSe2 lattice. More importantly, the strong interaction of ReSe2 with Au, with respect to that with SiO2/Si, is further confirmed by temperature-dependent Raman characterization. This work is thus proposed to shed light on the optical and thermal properties of such anisotropic two-dimensional three-atom-thick materials.

  13. Evidence for low temperature line-like behaviour of vortices in columnar defected Bi2Sr2CaCu2O8 single crystals

    International Nuclear Information System (INIS)

    Hebert, S; Perkins, G K; El-Salam, M Abd; Caplin, A D

    2003-01-01

    The interaction between vortices and columnar defects has been investigated in detail in Bi 2 Sr 2 CaCu 2 O 8 crystals irradiated with heavy ions along one direction, in one sample at 45 deg. from the c-axis, and in another at 75 deg. At all temperatures down to ∼30 K the irreversible magnetization is a maximum when the field is aligned with columns, although this peak is much more prominent at high temperatures and when the irreversibility field is approached. In the temperature-field-angle regime where the effect of the columns is dominant, the creep rate is close to 0.3, with little field or temperature dependence. These results can be understood in terms of line-like vortices, pinned both by columns and by point-like disorder, with much of the latter arising from collateral damage by the irradiation. The narrowness of the peak in the angular dependences is consistent with a locked state of the vortices to the columns

  14. Temperature Dependence of Charge Localization in High-Mobility, Solution-Crystallized Small Molecule Semiconductors Studied by Charge Modulation Spectroscopy

    DEFF Research Database (Denmark)

    Meneau, Aurélie Y. B.; Olivier, Yoann; Backlund, Tomas

    2016-01-01

    In solution-processable small molecule semiconductors, the extent of charge carrier wavefunction localization induced by dynamic disorder can be probed spectroscopically as a function of temperature using charge modulation spectroscopy (CMS). Here, it is shown based on combined fi eld-effect tran......In solution-processable small molecule semiconductors, the extent of charge carrier wavefunction localization induced by dynamic disorder can be probed spectroscopically as a function of temperature using charge modulation spectroscopy (CMS). Here, it is shown based on combined fi eld......-effect transistor and CMS measurements as a function of temperature that in certain molecular semiconductors, such as solution-processible pentacene, charge carriers become trapped at low temperatures in environments in which the charges become highly localized on individual molecules, while in some other molecules...

  15. Glass and crystallization like transitions at low temperature in Zr-Cu based glasses by internal friction measurements

    Directory of Open Access Journals (Sweden)

    Aboki A.T.

    2011-05-01

    Full Text Available Low temperature β internal friction peak evolution upon thermal cycles shows two peculiar peaks similar to high temperature internal friction peak. The modulus softening associated to these peaks suggest a phase transformation phenomenon and the relaxation time τo in order of 10-23–10-35s, close to that observed in grains boundary sliding are due to interface motions in the amorphous structure under combined thermal and mechanical energies.

  16. Temperature dependence of the mechanical properties of equiatomic solid solution alloys with face-centered cubic crystal structures

    International Nuclear Information System (INIS)

    Wu, Z.; Bei, H.; Pharr, G.M.; George, E.P.

    2014-01-01

    Compared to decades-old theories of strengthening in dilute solid solutions, the mechanical behavior of concentrated solid solutions is relatively poorly understood. A special subset of these materials includes alloys in which the constituent elements are present in equal atomic proportions, including the high-entropy alloys of recent interest. A unique characteristic of equiatomic alloys is the absence of “solvent” and “solute” atoms, resulting in a breakdown of the textbook picture of dislocations moving through a solvent lattice and encountering discrete solute obstacles. To clarify the mechanical behavior of this interesting new class of materials, we investigate here a family of equiatomic binary, ternary and quaternary alloys based on the elements Fe, Ni, Co, Cr and Mn that were previously shown to be single-phase face-centered cubic (fcc) solid solutions. The alloys were arc-melted, drop-cast, homogenized, cold-rolled and recrystallized to produce equiaxed microstructures with comparable grain sizes. Tensile tests were performed at an engineering strain rate of 10 −3 s −1 at temperatures in the range 77–673 K. Unalloyed fcc Ni was processed similarly and tested for comparison. The flow stresses depend to varying degrees on temperature, with some (e.g. NiCoCr, NiCoCrMn and FeNiCoCr) exhibiting yield and ultimate strengths that increase strongly with decreasing temperature, while others (e.g. NiCo and Ni) exhibit very weak temperature dependencies. To better understand this behavior, the temperature dependencies of the yield strength and strain hardening were analyzed separately. Lattice friction appears to be the predominant component of the temperature-dependent yield stress, possibly because the Peierls barrier height decreases with increasing temperature due to a thermally induced increase of dislocation width. In the early stages of plastic flow (5–13% strain, depending on material), the temperature dependence of strain hardening is due

  17. Post-growth annealing of Bridgman-grown CdZnTe and CdMnTe crystals for room-temperature nuclear radiation detectors

    International Nuclear Information System (INIS)

    Egarievwe, Stephen U.; Yang, Ge; Egarievwe, Alexander A.; Okwechime, Ifechukwude O.; Gray, Justin; Hales, Zaveon M.; Hossain, Anwar; Camarda, Giuseppe S.; Bolotnikov, Aleksey E.; James, Ralph B.

    2015-01-01

    Bridgman-grown cadmium zinc telluride (CdZnTe or CZT) and cadmium manganese telluride (CdMnTe or CMT) crystals often have Te inclusions that limit their performances as X-ray- and gamma-ray-detectors. We present here the results of post-growth thermal annealing aimed at reducing and eliminating Te inclusions in them. In a 2D analysis, we observed that the sizes of the Te inclusions declined to 92% during a 60-h annealing of CZT at 510 °C under Cd vapor. Further, tellurium inclusions were eliminated completely in CMT samples annealed at 570 °C in Cd vapor for 26 h, whilst their electrical resistivity fell by an order of 10 2 . During the temperature-gradient annealing of CMT at 730 °C and an 18 °C/cm temperature gradient for 18 h in a vacuum of 10 −5 mbar, we observed the diffusion of Te from the sample, so causing a reduction in size of the Te inclusions. For CZT samples annealed at 700 °C in a 10 °C/cm temperature gradient, we observed the migration of Te inclusions from a low-temperature region to a high one at 0.022 μm/s. During the temperature-gradient annealing of CZT in a vacuum of 10 −5 mbar at 570 °C and 30 °C/cm for 18 h, some Te inclusions moved toward the high-temperature side of the wafer, while other inclusions of the same size, i.e., 10 µm in diameter, remained in the same position. These results show that the migration, diffusion, and reaction of Te with Cd in the matrix of CZT- and CMT-wafers are complex phenomena that depend on the conditions in local regions, such as composition and structure, as well as on the annealing conditions

  18. High temperature oxidation behavior of aluminide on a Ni-based single crystal superalloy in different surface orientations

    Institute of Scientific and Technical Information of China (English)

    Fahamsyah H.Latief; Koji Kakehi; El-Sayed M.Sherif

    2014-01-01

    An investigation on oxidation behavior of coated Ni-based single crystal superalloy in different surface orientations has been carried out at 1100 1C. It has been found that the {100} surface shows a better oxidation resistance than the {110} one, which is attributed that the {110}surface had a slightly higher oxidation rate when compared to the {100} surface. The experimental results also indicated that the anisotropic oxidation behavior took place even with a very small difference in the oxidation rates that was found between the two surfaces. The differences of the topologically close packed phase amount and its penetration depth between the two surfaces, including the ratio of α-Al2O3 after 500 h oxidation, were responsible for the oxidation anisotropy.

  19. Pressure-induced amorphization of NaVO/sub 3 at room temperature and its re-crystallization

    International Nuclear Information System (INIS)

    Shen, Z.X.; Ong, C.W.; Tang, S.H.; Kuok, M.H.

    1994-01-01

    Pressure-induced amorphization is the subject of intense study for the past few years because of its importance in material science and in solid state physics. We reported a crystalline-amorphous phase transition at ca 60kbar in NaVO1/3, which is the lowest pressure for such transitions in ionic crystals. The transition is marked by the sudden appearance of very broad bands at the 800 and 350 cm/sup -1 regions. The amorphization includes the complete breaking up of the infinite chains of corner-linked tetrahedral VO/sub 4, most likely into VO/sup -/sub 3. On decompression, the amorphous phase transforms to another phase, probably also amorphous at ca 40 kbar. It reverts to the stable ambient condition α-phase upon heating. Here we report on the details of the transtitional region and the re-linking of the VO/sub 4 chains upon heating. (authors)

  20. One-dimensional photonic crystals with a planar oriented nematic layer: Temperature and angular dependence of the spectra of defect modes

    International Nuclear Information System (INIS)

    Arkhipkin, V. G.; Gunyakov, V. A.; Myslivets, S. A.; Gerasimov, V. P.; Zyryanov, V. Ya.; Vetrov, S. Ya.; Shabanov, V. F.

    2008-01-01

    Transmission spectra of a one-dimensional photonic crystal (PC) formed by two multilayer dielectric mirrors and a planar oriented layer of 5CB nematic liquid crystal (LC) that is sandwiched between these mirrors and serves as a structure defect are investigated experimentally. Specific features of the behavior of the spectrum of defect modes as a function of the angle of incidence of light on the crystal are studied for two polarizations: parallel and perpendicular to the director of the LC; the director either lies in the plane of incidence or is perpendicular to it. It is shown that, for the configurations considered, the maxima of the defect modes shift toward the short-wavelength region as the tilt angle of incidence radiation increases; this tendency is more manifest for the parallel-polarized component, when the director lies in the plane of incidence. In the latter case, the width of the photonic band gap (PBG) appreciably decreases. The temperature dependence of the polarization components of the transmission spectra of a PC is investigated in the case of normal incidence of light. The spectral shift of defect modes due to the variation of the refractive index of the LC at the nematic-isotropic liquid phase transition point is measured. It is shown that, in real PCs, the amplitude of defect modes decreases when approaching the center of the band gap, as well as when the number of layers in the dielectric mirrors increases. Theoretical transmission spectra of the PCs calculated by the method of recurrence relations with regard to the decay of defect modes are in good agreement with experimental data.

  1. EPR spectroscopy of MRI-related Gd(III) complexes: simultaneous analysis of multiple frequency and temperature spectra, including static and transient crystal field effects.

    Science.gov (United States)

    Rast, S; Borel, A; Helm, L; Belorizky, E; Fries, P H; Merbach, A E

    2001-03-21

    For the first time, a very general theoretical method is proposed to interpret the full electron paramagnetic resonance (EPR) spectra at multiple temperatures and frequencies in the important case of S-state metal ions complexed in liquid solution. This method is illustrated by a careful analysis of the measured spectra of two Gd3+ (S = 7/2) complexes. It is shown that the electronic relaxation mechanisms at the origin of the EPR line shape arise from the combined effects of the modulation of the static crystal field by the random Brownian rotation of the complex and of the transient zero-field splitting. A detailed study of the static crystal field mechanism shows that, contrarily to the usual global models involving only second-order terms, the fourth and sixth order terms can play a non-negligible role. The obtained parameters are well interpreted in the framework of the physics of the various underlying relaxation processes. A better understanding of these mechanisms is highly valuable since they partly control the efficiency of paramagnetic metal ions in contrast agents for medical magnetic resonance imaging (MRI).

  2. Polarization-selective three-photon absorption and subsequent photoluminescence in CsPbBr3 single crystal at room temperature

    Science.gov (United States)

    Clark, D. J.; Stoumpos, C. C.; Saouma, F. O.; Kanatzidis, M. G.; Jang, J. I.

    2016-05-01

    We report on highly polarization-selective three-photon absorption (3PA) in a Bridgman-grown single crystal of CsPbBr3 oriented along the (112) direction, which is an inorganic counterpart to emerging organic-inorganic hybrid halide perovskites for solar-cell and optoelectronic applications. The crystal exhibits strong photoluminescence (PL) at room temperature as a direct consequence of 3PA of fundamental radiation. Interestingly, 3PA disappears when the input polarization is parallel to the (-110 ) direction. This 3PA effect is strongest when orthogonal to (-110 ) and the corresponding 3PA coefficient was measured to be γ =0.14 ±0.03 cm3/GW2 under picosecond-pulse excitation at the fundamental wavelength of λ =1200 nm. The laser-induced damage threshold was also determined to be about 20 GW/cm2 at the same wavelength. Based on relative PL intensities upon λ tuning over the entire 3PA range (1100 -1700 nm), we determined the nonlinear optical dispersion of the 3PA coefficient for CsPbBr3, which is consistent with a theoretical prediction. Experimentally observed significant polarization dependence of γ was explained by relevant selection rules. The perovskite is potentially important for nonlinear optical applications owing to its highly efficient 3PA-induced PL response with a sharp on/off ratio by active polarization control.

  3. Room temperature direct bonding of LiNbO3 crystal layers and its application to high-voltage optical sensing

    International Nuclear Information System (INIS)

    Tulli, D; Janner, D; Pruneri, V

    2011-01-01

    LiNbO 3 is a crystal widely used in photonics and acoustics, for example in electro-optic modulation, nonlinear optical frequency conversion, electric field sensing and surface acoustic wave filtering. It often needs to be combined with other materials and used in thin layers to achieve the adequate device performance. In this paper, we investigate direct bonding of LiNbO 3 crystals with other dielectric materials, such as Si and fused silica (SiO 2 ), and we show that specific surface chemical cleaning, together with Ar or O 2 plasma activation, can be used to increase the surface free energy and achieve effective bonding at room temperature. The resulting hybrid material bonding is very strong, making the dicing and grinding of LiNbO 3 layers as thin as 15 µm possible. To demonstrate the application potentials of the proposed bonding technique, we have fabricated and characterized a high-voltage field sensor with high sensitivity in a domain inverted and bonded LiNbO 3 waveguide substrate

  4. On the induction of homogeneous bulk crystallization in Eu-doped calcium aluminosilicate glass by applying simultaneous high pressure and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Muniz, R. F., E-mail: robsonfmuniz@yahoo.com.br [Institut Lumière Matière, UMR 5306 CNRS-Université Lyon 1, Université de Lyon, 69622 Villeurbanne (France); Departamento de Física, Universidade Estadual de Maringá, 87020900, Maringá, PR (Brazil); Ligny, D. de [Department of Materials Science, Glass and Ceramics, University of Erlangen Nürnberg, Martensstr. 5, 91058 Erlangen (Germany); Le Floch, S.; Martinet, C.; Guyot, Y. [Institut Lumière Matière, UMR 5306 CNRS-Université Lyon 1, Université de Lyon, 69622 Villeurbanne (France); Rohling, J. H.; Medina, A. N.; Sandrini, M.; Baesso, M. L. [Departamento de Física, Universidade Estadual de Maringá, 87020900, Maringá, PR (Brazil); Andrade, L. H. C.; Lima, S. M. [Grupo de Espectroscopia Óptica e Fototérmica, Universidade Estadual de Mato Grosso do Sul, C.P. 351, Dourados, MS (Brazil)

    2016-06-28

    From initial calcium aluminosilicate glass, transparent glass-ceramics have been successfully synthesized under simultaneous high pressure and temperature (SHPT). Possible homogeneous volumetric crystallization of this glassy system, which was not achieved previously by means of conventional heat treatment, has been put in evidence with a SHPT procedure. Structural, mechanical, and optical properties of glass and glass-ceramic obtained were investigated. Raman spectroscopy and X-ray diffraction allowed to identify two main crystalline phases: merwinite [Ca{sub 3}Mg(SiO{sub 4}){sub 2}] and diopside [CaMgSi{sub 2}O{sub 6}]. A Raman scanning profile showed that the formation of merwinite is quite homogeneous over the bulk sample. However, the sample surface also contains significant diopside crystals. Instrumented Berkovich nanoindentation was applied to determine the effect of SHPT on hardness from glass to glass-ceramic. For Eu-doped samples, the broadband emission due to 4f{sup 6}5d{sup 1} → 4f{sup 7} transition of Eu{sup 2+} was studied in both host systems. Additionally, the {sup 5}D{sub 0} → {sup 7}F{sub J} transition of Eu{sup 3+} was used as an environment probe in the pristine glass and the glass-ceramic.

  5. Orientation and temperature dependence of yield stress and slip geometry of Ti3Al and Ti3Al-V single crystals

    International Nuclear Information System (INIS)

    Umakoshi, Y.; Nakano, T.; Takenaka, T.; Sumimoto, K.; Yamane, T.

    1993-01-01

    Single crystals of binary Ti 3 Al and ternary Ti 3 Al-V alloys with the D0 19 structure were deformed in compression at 20-900 C. Slip systems of the (10 bar 10) -type and the (11 bar 21) -type were observed in these alloys throughout the entire temperature range depending on orientation, but the (11 bar 21) -slip was limited to orientations near [0001]. The basal (0001) -slip was also activated in quenched Ti 3 Al. The CRSS for the (10 bar 10) -slip in the binary and ternary alloys decreases monotonically with increasing temperature. In the ternary alloy the CRSS for the (10 bar 10) -slip shows a violation of Schmid's law, while the binary alloy obeys the CRSS law. When Ti 3 Al is deformed by (11 bar 21) -slip the CRSS for the slip exhibits an anomalous peak in the temperature-CRSS curve but the addition of vanadium suppresses the extent of the anomalous strengthening

  6. Effect of temperature on terahertz photonic and omnidirectional band gaps in one-dimensional quasi-periodic photonic crystals composed of semiconductor InSb.

    Science.gov (United States)

    Singh, Bipin K; Pandey, Praveen C

    2016-07-20

    Engineering of thermally tunable terahertz photonic and omnidirectional bandgaps has been demonstrated theoretically in one-dimensional quasi-periodic photonic crystals (PCs) containing semiconductor and dielectric materials. The considered quasi-periodic structures are taken in the form of Fibonacci, Thue-Morse, and double periodic sequences. We have shown that the photonic and omnidirectional bandgaps in the quasi-periodic structures with semiconductor constituents are strongly depend on the temperature, thickness of the constituted semiconductor and dielectric material layers, and generations of the quasi-periodic sequences. It has been found that the number of photonic bandgaps increases with layer thickness and generation of the quasi-periodic sequences. Omnidirectional bandgaps in the structures have also been obtained. Results show that the bandwidths of photonic and omnidirectional bandgaps are tunable by changing the temperature and lattice parameters of the structures. The generation of quasi-periodic sequences can also change the properties of photonic and omnidirectional bandgaps remarkably. The frequency range of the photonic and omnidirectional bandgaps can be tuned by the change of temperature and layer thickness of the considered quasi-periodic structures. This work will be useful to design tunable terahertz PC devices.

  7. Effect of dose rate, temperature and impurity content on the radiation damage in the electron irradiated NaCl crystals

    NARCIS (Netherlands)

    Dubinko, V.I.; Turkin, A.A.; Vainshtein, D.I.; Hartog, H.W. den

    The dependencies of void formation and radiolytic sodium accumulation on the irradiation dose, dose rate, temperature and impurity content are analyzed within a framework of a theoretical model, which is based on a new mechanism of dislocation climb. The mechanism involves the production of V-F

  8. A phononic crystal strip based on silicon for support tether applications in silicon-based MEMS resonators and effects of temperature and dopant on its band gap characteristics

    Directory of Open Access Journals (Sweden)

    Thi Dep Ha

    2016-04-01

    Full Text Available Phononic crystals (PnCs and n-type doped silicon technique have been widely employed in silicon-based MEMS resonators to obtain high quality factor (Q as well as temperature-induced frequency stability. For the PnCs, their band gaps play an important role in the acoustic wave propagation. Also, the temperature and dopant doped into silicon can cause the change in its material properties such as elastic constants, Young’s modulus. Therefore, in order to design the simultaneous high Q and frequency stability silicon-based MEMS resonators by two these techniques, a careful design should study effects of temperature and dopant on the band gap characteristics to examine the acoustic wave propagation in the PnC. Based on these, this paper presents (1 a proposed silicon-based PnC strip structure for support tether applications in low frequency silicon-based MEMS resonators, (2 influences of temperature and dopant on band gap characteristics of the PnC strips. The simulation results show that the largest band gap can achieve up to 33.56 at 57.59 MHz and increase 1280.13 % (also increase 131.89 % for ratio of the widest gaps compared with the counterpart without hole. The band gap properties of the PnC strips is insignificantly effected by temperature and electron doping concentration. Also, the quality factor of two designed length extensional mode MEMS resonators with proposed PnC strip based support tethers is up to 1084.59% and 43846.36% over the same resonators with PnC strip without hole and circled corners, respectively. This theoretical study uses the finite element analysis in COMSOL Multiphysics and MATLAB softwares as simulation tools. This findings provides a background in combination of PnC and dopant techniques for high performance silicon-based MEMS resonators as well as PnC-based MEMS devices.

  9. A phononic crystal strip based on silicon for support tether applications in silicon-based MEMS resonators and effects of temperature and dopant on its band gap characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Thi Dep, E-mail: hathidep@yahoo.com [School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731 (China); Faculty of Electronic Technology, Industrial University of Ho Chi Minh City, Hochiminh City (Viet Nam); Bao, JingFu, E-mail: baojingfu@uestc.edu.cn [School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731 (China)

    2016-04-15

    Phononic crystals (PnCs) and n-type doped silicon technique have been widely employed in silicon-based MEMS resonators to obtain high quality factor (Q) as well as temperature-induced frequency stability. For the PnCs, their band gaps play an important role in the acoustic wave propagation. Also, the temperature and dopant doped into silicon can cause the change in its material properties such as elastic constants, Young’s modulus. Therefore, in order to design the simultaneous high Q and frequency stability silicon-based MEMS resonators by two these techniques, a careful design should study effects of temperature and dopant on the band gap characteristics to examine the acoustic wave propagation in the PnC. Based on these, this paper presents (1) a proposed silicon-based PnC strip structure for support tether applications in low frequency silicon-based MEMS resonators, (2) influences of temperature and dopant on band gap characteristics of the PnC strips. The simulation results show that the largest band gap can achieve up to 33.56 at 57.59 MHz and increase 1280.13 % (also increase 131.89 % for ratio of the widest gaps) compared with the counterpart without hole. The band gap properties of the PnC strips is insignificantly effected by temperature and electron doping concentration. Also, the quality factor of two designed length extensional mode MEMS resonators with proposed PnC strip based support tethers is up to 1084.59% and 43846.36% over the same resonators with PnC strip without hole and circled corners, respectively. This theoretical study uses the finite element analysis in COMSOL Multiphysics and MATLAB softwares as simulation tools. This findings provides a background in combination of PnC and dopant techniques for high performance silicon-based MEMS resonators as well as PnC-based MEMS devices.

  10. Origin of dislocation luminescence centers and their reorganization in p-type silicon crystal subjected to plastic deformation and high temperature annealing.

    Science.gov (United States)

    Pavlyk, Bohdan; Kushlyk, Markiyan; Slobodzyan, Dmytro

    2017-12-01

    Changes of the defect structure of silicon p-type crystal surface layer under the influence of plastic deformation and high temperature annealing in oxygen atmosphere were investigated by deep-level capacitance-modulation spectroscopy (DLCMS) and IR spectroscopy of molecules and atom vibrational levels. Special role of dislocations in the surface layer of silicon during the formation of its energy spectrum and rebuilding the defective structure was established. It is shown that the concentration of linear defects (N ≥ 10 4  cm -2 ) enriches surface layer with electrically active complexes (dislocation-oxygen, dislocation-vacancy, and dislocation-interstitial atoms of silicon) which are an effective radiative recombination centers.

  11. Crystal structure and Temperature-Dependent Luminescence Characteristics of KMg4(PO4)3:Eu2+ phosphor for White Light-emitting diodes

    Science.gov (United States)

    Chen, Jian; Liu, Yangai; Mei, Lefu; Liu, Haikun; Fang, Minghao; Huang, Zhaohui

    2015-01-01

    The KMg4(PO4)3:Eu2+ phosphor was prepared by the conventional high temperature solid-state reaction. The crystal structure, luminescence and reflectance spectra, thermal stability, quantum efficiency and the application for N-UV LED were studied respectively. The phase formation and crystal structure of KMg4(PO4)3:Eu2+ were confirmed from the powder X-ray diffraction and the Rietveld refinement. The concentration quenching of Eu2+ in the KMg4(PO4)3 host was determined to be 1mol% and the quenching mechanism was certified to be the dipole–dipole interaction. The energy transfer critical distance of as-prepared phosphor was calculated to be about 35.84Å. Furthermore, the phosphor exhibited good thermal stability and the corresponding activation energy ΔE was reckoned to be 0.24eV. Upon excitation at 365nm, the internal quantum efficiency of the optimized KMg4(PO4)3:Eu2+ was estimated to be 50.44%. The white N-UV LEDs was fabricated via KMg4(PO4)3:Eu2+, green-emitting (Ba,Sr)2SiO4:Eu2+, and red-emitting CaAlSiN3:Eu2+ phosphors with a near-UV chip. The excellent color rendering index (Ra = 96) at a correlated color temperature (5227.08K) with CIE coordinates of x = 0.34, y = 0.35 of the WLED device indicates that KMg4(PO4)3:Eu2+ is a promising blue-emitting phosphor for white N-UV light emitting diodes (LEDs). PMID:25855866

  12. Crystal structure and magnetoresistance of La0.7Ca0.3MnO3 perovskite at room temperature

    International Nuclear Information System (INIS)

    Engkir Sukirman; Wisnu Ari Adi; Yustinus Purwamargapratala

    2012-01-01

    A comparative study on crystal structure and magnetoresistance (MR) of La 0.7 Ca 0.3 MnO 3 (LCMO) perovskite toward LaMnO 3 (LMO) and CaMnO 3 (CMO) parent compounds have been carried out to study the change of LCMO due to magnetic fields variations at room temperature. The LCMO, LMO and CMO were synthesized using high energy milling (HEM) method. The precursors obtained were pressed into pellet and sintered at T s = 1350°C for 6 hours. The qualitative analysis were conducted by x-rays diffraction technique using Rietveld method. The MR effect on the samples were measured using four point probe (FPP) method and the surface structure of pellets were observed by scanning electron microscope (SEM). The samples have the same crystal structure, namely orthorhombic, space group: Pnma, No. 62. The lattice parameters of LCMO were successfully confirmed until four decimal precision, namely a = 5.4851(3) Å, b = 7.7601(4) Å, c = 5.5185(2) Å. The lattice parameters for LMO and CMO successively are a = 5.4405(9) Å, b = 7.717(1) Å, c = 5.537(1) Å and a = 5.2973(6) Å, b = 7.477(1) Å, c = 5.281 (1) Å. All samples have grain diameter of around 1,000 nm with a globule like form and every grain consists of 27 crystallites. The MR for LCMO, LMO and CMO samples at room temperature are -10.1; -7.3 dan -12.3%, respectively, and comparable with the one of multilayers based GMR [Cu/NiFeCo] x10 /Ta. The LCMO perovskite bulk can be used to detect the magnetic microbeads and ferrofluid. (author)

  13. Piezoresistive pressure sensor using low-temperature aluminium induced crystallization of sputter-deposited amorphous silicon film

    International Nuclear Information System (INIS)

    Tiwari, Ruchi; Chandra, Sudhir

    2013-01-01

    In the present work, we have investigated the piezoresistive properties of silicon films prepared by the radio frequency magnetron sputtering technique, followed by the aluminium induced crystallization (AIC) process. Orientation and grain size of the polysilicon films were studied by x-ray diffraction analysis and found to be in the range 30–50 nm. Annealing of the Al–Si stack on an oxidized silicon substrate was performed in air ambient at 300–550 °C, resulting in layer exchange and transformation from amorphous to polysilicon phase. Van der Pauw and Hall measurement techniques were used to investigate the sheet resistance and carrier mobility of the resulting polycrystalline silicon film. The effect of Al thickness on the sheet resistance and mobility was also studied in the present work. A piezoresistive pressure sensor was fabricated on an oxidized silicon substrate in a Wheatstone bridge configuration, comprising of four piezoresistors made of polysilicon film obtained by the AIC process. The diaphragm was formed by the bulk-micromachining of silicon substrate. The response of the pressure sensor with applied negative pressure in 10–95 kPa range was studied. The gauge factor was estimated to be 5 and 18 for differently located piezoresistors on the diaphragm. The sensitivity of the pressure sensor was measured to be ∼ 30 mV MPa −1 , when the Wheatstone bridge was biased at 1 V input voltage. (paper)

  14. Anatomy of Forehead, Glabellar, Nasal and Orbital Muscles, and Their Correlation with Distinctive Patterns of Skin Lines on the Upper Third of the Face: Reviewing Concepts.

    Science.gov (United States)

    Abramo, Antonio Carlos; Do Amaral, Thiago Paoliello Alves; Lessio, Bruno Pierotti; De Lima, Germano Andrighetto

    2016-12-01

    The purpose of this study is to establish a relationship between the skin lines on the upper third of the face in cadavers, which represent the muscle activity in life and the skin lines achieved by voluntary contraction of the forehead, glabellar, and orbital muscles in patients. Anatomical dissection of fresh cadavers was performed in 20 fresh cadavers, 11 females and 9 males, with ages ranging from 53 to 77 years. Subcutaneous dissection identified the muscle shape and the continuity of the fibers of the eyebrow elevator and depress muscles. Subgaleal dissection identified the cutaneous insertions of the muscles. They were correlated with skin lines on the upper third of the face of the cadavers that represent the muscle activity in life. Voluntary contraction was performed by 20 voluntary patients, 13 females and 7 males, with ages ranging from 35 to 62 years. Distinct patterns of skin lines on the forehead, glabellar and orbital areas, and eyebrow displacement were identified. The frontalis exhibited four anatomical shapes with four different patterns of horizontal parallel lines on the forehead skin. The corrugator supercilii showed three shapes of muscles creating six patterns of vertical glabellar lines, three symmetrical and three asymmetrical. The orbicularis oculi and procerus had single patterns. The skin lines exhibited in voluntary contraction of the upper third of the face in patients showed the same patterns of the skin lines achieved in cadavers. Skin lines in cadavers, which are the expression of the muscle activity in life, were similar to those achieved in the voluntary contraction of patients, allowing us to assert that the muscle patterns of patients were similar to those identified in cadavers. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies

  15. Low-temperature growth of highly crystallized transparent conductive fluorine-doped tin oxide films by intermittent spray pyrolysis deposition

    Energy Technology Data Exchange (ETDEWEB)

    Fukano, Tatsuo; Motohiro, Tomoyoshi [Toyota Central Research and Development Laboratories Inc., Nagakute, Aichi 480-1192 (Japan)

    2004-05-30

    Following the procedure by Sawada et al. (Thin Solid Films 409 (2002) 46), high-quality SnO{sub 2}:F films were grown on glass substrates at relatively low temperatures of 325-340C by intermittent spray pyrolysis deposition using a perfume atomizer for cosmetics use. Even though the substrate temperature is low, as-deposited films show a high optical transmittance of 92% in the visible range, a low electric resistivity of 5.8x10{sup -4}{omega}cm and a high Hall mobility of 28cm{sup 2}/Vs. The F/Sn atomic ratio (0.0074) in the films is low in comparison with the value (0.5) in the sprayed solution. The carrier density in the film is approximately equal to the F-ion density, suggesting that most of the F-ions effectively function as active dopants. Films' transmittance and resistivity show little change after a 450C 60min heat treatment in the atmosphere, evidencing a high heat resistance. The SnO{sub 2}:F films obtained in this work remove the difficulty to improve the figure of merit at low synthesis temperatures.

  16. Flux free growth of large FeSe1/2Te1/2 superconducting single crystals by an easy high temperature melt and slow cooling method

    Directory of Open Access Journals (Sweden)

    P. K. Maheshwari

    2015-09-01

    Full Text Available We report successful growth of flux free large single crystals of superconducting FeSe1/2Te1/2 with typical dimensions of up to few cm. The AC and DC magnetic measurements revealed the superconducting transition temperature (Tc value of around 11.5K and the isothermal MH showed typical type-II superconducting behavior. The lower critical field (Hc1 being estimated by measuring the low field isothermal magnetization in superconducting regime is found to be above 200Oe at 0K. The temperature dependent electrical resistivity ρ(T  showed the Tc (onset to be 14K and the Tc(ρ = 0 at 11.5K. The electrical resistivity under various magnetic fields i.e., ρ(TH for H//ab and H//c demonstrated the difference in the width of Tc with applied field of 14Tesla to be nearly 2K, confirming the anisotropic nature of superconductivity. The upper critical and irreversibility fields at absolute zero temperature i.e., Hc2(0 and Hirr(0 being determined by the conventional one-band Werthamer–Helfand–Hohenberg (WHH equation for the criteria of normal state resistivity (ρn falling to 90% (onset, and 10% (offset is 76.9Tesla, and 37.45Tesla respectively, for H//c and 135.4Tesla, and 71.41Tesla respectively, for H//ab. The coherence length at the zero temperature is estimated to be above 20Å ´ by using the Ginsburg-Landau theory. The activation energy for the FeSe1/2Te1/2 in both directions H//c and H//ab is determined by using Thermally Activation Flux Flow (TAFF model.

  17. Precipitation in solid solution and structural transformations in single crystals of high rhenium ruthenium-containing nickel superalloys at high-temperature creep

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A.A.; Petrushin, N.V.; Zaitsev, D.V.; Treninkov, I.A.; Filonova, E.V. [All-Russian Scientific Research Institute of Aviation Materials (VIAM), Moscow (Russian Federation)

    2010-07-01

    The phase composition and structure of single crystals of two superalloys (alloy 1 and alloy 2) were investigated in this work. For alloy 1 (Re - 9 wt%) the kinetics of precipitation in solid solution at heat treatment (HT) was investigated. TEM and X-Ray examinations have revealed that during HT rhombic phase (R-phase) precipitation (Immm class (BCR)) occurs. The TTT diagram is plotted, it contains the time-temperature area of the existence of R-phase particles. The element content of R-phase is identified (at. %): Re- 51.5; Co- 23.5; Cr- 14.8; Mo- 4.2; W- 3.3; Ta- 2.7. For alloy 2 (Re - 6.5 wt %, Ru - 4 wt %) structural transformations at high-temperature creep are investigated. By dark-field TEM methods it is established, that in alloy 2 the additional phase with a rhombic lattice is formed during creep. Particles of this phase precipitate in {gamma}-phase and their quantity increases during high-temperature creep. It is revealed that during creep 3-D dislocation network is formed in {gamma}-phase. At the third stage of creep the process of inversion structure formation is observed in the alloy, i.e. {gamma}'-phase becomes a matrix. Thus during modeling creep the volume fraction of {gamma}'-phase in the samples increases from 30% (at creep duration of 200 hrs) up to 55% (at 500 hrs). The processes of structure formation in Re and Ru-containing nickel superalloys are strongly affected by decomposition of solid solution during high-temperature creep that includes precipitation of additional TCP-phases. (orig.)

  18. Temperature-induced spin reorientation and magnetization jump of rare-earth orthoferrite Ho{sub 0.5}Pr{sub 0.5}FeO{sub 3} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guohua; Zhao, Weiyao; Cao, Yiming; Kang, Baojuan [Department of Physics, and International Center of Quantum and Molecular Structures, Shanghai University, Shanghai 200444 (China); Zhang, Jincang [Department of Physics, and International Center of Quantum and Molecular Structures, Shanghai University, Shanghai 200444 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University, Shanghai 200444 (China); Ren, Wei, E-mail: renwei@shu.edu.cn [Department of Physics, and International Center of Quantum and Molecular Structures, Shanghai University, Shanghai 200444 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University, Shanghai 200444 (China); Cao, Shixun, E-mail: sxcao@shu.edu.cn [Department of Physics, and International Center of Quantum and Molecular Structures, Shanghai University, Shanghai 200444 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University, Shanghai 200444 (China)

    2016-07-25

    We report temperature-induced spin reorientation and magnetization jump effects in the rare earth (RE) orthoferrite Ho{sub 0.5}Pr{sub 0.5}FeO{sub 3} single crystal. The single crystal of about 6 mm in diameter and 50 mm in length was successfully grown by optical floating zone method. Both X-ray diffraction and Laue photograph confirmed the homogeneity and high quality of the crystal. Magnetic properties of Ho{sub 0.5}Pr{sub 0.5}FeO{sub 3} single crystal are studied over a wide temperature range from 2 to 300 K. Spin reorientation transition from Γ{sub 2} to Γ{sub 4} phase is observed in the temperature range of 75–90 K. At lower temperature, the Ho{sub 0.5}Pr{sub 0.5}FeO{sub 3} shows an abrupt jump of magnetization along the a-axis, which occurs only in the field-cooling process, and is sensitive to external applied magnetic field. By analyzing the jump temperature and magnitude of the magnetization, we conclude that it is caused by the spin reversal of the rare earth ions. The isothermal magnetization versus field hysteresis loop measurements along a axis explain the spin configuration variation from 3 K to 60 K. - Highlights: • Ho{sub 0.5}Pr{sub 0.5}FeO{sub 3} single crystal was grown by optical floating zone method. • It shows an abrupt jump of magnetization along a axis at low temperature. • The jump height and temperature is sensitive to external applied magnetic field. • It is attributed to the spin reversal of the rare earth ions.

  19. Neutron diffusion study of the crystal field action on the Er3+ ion in supraconductors with high critical temperature

    International Nuclear Information System (INIS)

    Mesot, J.

    1992-11-01

    Superconductivity in the cuprates is believed to be controlled by the density of mobile charges in the CuO 2 planes. In particular, the charge transfer process from the chains to the planes seems to play an important role. Consequently, it is crucial to observe directly the influence of different types of perturbations on the electronic structure of these compounds. The crystal field (CF) spectroscopy of the rare earth allows us to make these observations, since in the perovskite-type compounds YBa 2 Cu 3 O x (123) and YBa 2 Cu 4 O 8 (1248) the replacement of the Y ions by most of the magnetic rare-earth (R) ions does not have a detrimental effect on the superconductivity. The (2J+1)-fold degeneracy of the ground-state J-multiplet of the R ions will be partially lifted under the action of the CF potential created by the neighbouring atoms. By means of inelastic neutron scattering experiments it is possible to observe directly the transitions between the CF states. This means that we can obtain useful information on both the structural and the charge distribution parameters in the vicinity of the R ion. In the 123 and 1248 systems, the R ions are sandwiched between two CuO 2 planes, thus the CF interaction at the R sites constitutes an ideal probe of the local symmetry and charge distribution of the superconducting planes. In the first part of this work, we discuss the importance of the intermediate coupling and J mixing effects on the determination of the CF parameters of the 123 compounds. In order to quantify the charge transfer process from the chains to the planes, we performed a detailed analysis of the CF of Er 3+ in the 123 and 248 compounds under the following conditions: oxygen deficiency, Zn and Ni doping of the Cu sites, external pressure and fast neutron irradiation. In parallel, we present conclusions obtained from diffraction experiments. (author) figs., tabs., 113 refs

  20. Creep of crystals

    International Nuclear Information System (INIS)

    Poirier, J.-P.

    1988-01-01

    Creep mechanisms for metals, ceramics and rocks, effect of pressure and temperature on deformation processes are considered. The role of crystal defects is analysed, different models of creep are described. Deformation mechanisms maps for different materials are presented