WorldWideScience

Sample records for plate-shaped single crystals

  1. Plate-shaped Yb:LuPO4 crystal for efficient CW and passively Q-switched microchip lasers

    Science.gov (United States)

    Liu, Junhai; Wang, Lisha; Han, Wenjuan; Xu, Honghao; Zhong, Degao; Teng, Bing

    2016-10-01

    It is demonstrated that plate-shaped crystals of Yb:LuPO4, which are grown from spontaneous nucleation by high-temperature solution method, can be utilized to make microchip lasers operating in continuous-wave (CW) or passively Q-switched mode. Efficient operation of such a microchip laser, which is built with a 0.3 mm thick crystal plate in a 2 mm long plane-parallel cavity, is realized at room temperature. With 2.37 W of pump power absorbed, 1.45 W of CW output power is generated with a slope efficiency of 73%. When passively Q-switched with a Cr4+:YAG crystal plate as saturable absorber, the laser produces a maximum pulsed output power of 0.53 W at 1013.3 nm, at a pulse repetition rate of 23.8 kHz, the resulting pulse energy, duration, and peak power are 22.3 μJ, 4.0 ns, and 5.6 kW, respectively.

  2. SINGLE CRYSTAL NEUTRON DIFFRACTION.

    Energy Technology Data Exchange (ETDEWEB)

    KOETZLE,T.F.

    2001-03-13

    Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.

  3. Single Crystal Surfaces

    Science.gov (United States)

    Aguilar-Santillan, Joaquin

    2014-06-01

    The present work studies (0001) Al2O3 and (111) Al2MgO4 wetting with pure molten Al by the sessile drop technique from 1073 K to 1473 K (800 °C to 1200 °C) under Ar at PO2 10-15 Pa. Al pure liquid wets a smooth and chemically homogeneous surface of an inert solid, the wetting driving force ( t, T) can be readily studied when surface solid roughness increases in the system. Both crystals planes (0001) Al2O3 and (111) Al2MgO4 have crystallographic surfaces with identical O-2 crystalline positions however considering Mg2+ content in Al2MgO4 structure may influence a reactive mode. Kinetic models results under similar experimental conditions show that Al wetting on (0001) Al2O3 is less reactive than (111) Al2MgO4, however at >1273 K (1000 °C) (0001) Al2O3 transformation occurs and a transition of wetting improves. The (111) Al2MgO4 and Al system promotes interface formations that slow its wetting process.

  4. Crystal ball single event display

    Energy Technology Data Exchange (ETDEWEB)

    Grosnick, D.; Gibson, A. [Valparaiso Univ., IN (United States). Dept. of Physics and Astronomy; Allgower, C. [Argonne National Lab., IL (United States). High Energy Physics Div.; Alyea, J. [Valparaiso Univ., IN (United States). Dept. of Physics and Astronomy]|[Argonne National Lab., IL (United States). High Energy Physics Div.

    1997-10-15

    The Single Event Display (SED) is a routine that is designed to provide information graphically about a triggered event within the Crystal Ball. The SED is written entirely in FORTRAN and uses the CERN-based HICZ graphing package. The primary display shows the amount of energy deposited in each of the NaI crystals on a Mercator-like projection of the crystals. Ten different shades and colors correspond to varying amounts of energy deposited within a crystal. Information about energy clusters is displayed on the crystal map by outlining in red the thirteen (or twelve) crystals contained within a cluster and assigning each cluster a number. Additional information about energy clusters is provided in a series of boxes containing useful data about the energy distribution among the crystals within the cluster. Other information shown on the event display include the event trigger type and data about {pi}{sup o}`s and {eta}`s formed from pairs of clusters as found by the analyzer. A description of the major features is given, along with some information on how to install the SED into the analyzer.

  5. High-Pressure Synthesis of SmFeAsO{sub 1-x}F{sub x}(x=0.2) Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Sook; Park, Jae Hyun; Lee, Jae Yeap; Lee, Hu Jong [Dept. of Physics, Pohang University of Science and Technology, Pohang (Korea, Republic of); Kim, Ju Young; Cho, B. K. [Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Jung, Chang Uk [Dept. of Physics, Hankuk University of Foreign Studies, Yongin (Korea, Republic of)

    2009-04-15

    Fluorine-doped SmFeAsO{sub 1-x}F{sub x} single crystals with the nominal value of x=0.2 were grown at 1350-1450 degrees C under the pressure of 3.3 GPa by using the self-flux method. Plate-shaped single crystals in the range of a few-150 {mu}m in their lateral size were obtained. The detailed crystal structure was analyzed by using the x-ray diffractometry. Superconducting transition temperature, determined by the resistive transition, of a single crystal was about 49 K with a narrow resistive transition width of {approx}K. A relatively sharp transition, a low residual resistivity, and a large residual resistivity ratio compared with those reported for REFeAsO{sub 1-x}F{sub x}(RE=Sm, Nd) single crystals indicate the high quality of our single crystals.

  6. Stacking fault energy in some single crystals

    Institute of Scientific and Technical Information of China (English)

    Aditya M.Vora

    2012-01-01

    The stacking fault energy of single crystals has been reported using the peak shift method.Presently studied all single crystals are grown by using a direct vapor transport (DVT) technique in the laboratory.The structural characterizations of these crystals are made by XRD.Considerable variations are shown in deformation (α) and growth (β) probabilities in single crystals due to off-stoichiometry,which possesses the stacking fault in the single crystal.

  7. Crystallization Growth of Single Crystal Cu by ContinuousCasting

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Crystallization growth of single-crystal Cu by continuous casting has been investigated using selfdesigned horizontal continuous casting equipment and XRD. Experimental results showed that the crystallization plane of (311), (220) and (111) were eliminated sequentially in evolutionary process. The final growth plane of crystal was (200), the direction of crystallization was [100],the growth direction of both sides of the rod inclined to axis, and the degree of deviation of direction [100] from the crystal axis was less than 10. In order to produce high quality single crystal, the solid-liquid interface morphology must be smooth, even be planar.

  8. Single Crystals (M = Fe, Co)

    Science.gov (United States)

    Cabrera-Baez, M.; Magnavita, E. Thizay; Ribeiro, Raquel A.; Avila, Marcos A.

    2014-06-01

    FeGa3 and related compounds have been subjects of recent investigation for their interesting thermoelectric, electronic, and magnetic behaviors. Here, single crystals of FeGa3- y Ge y were grown by the self-flux technique with effective y = 0, 0.09(1), 0.11(1), and 0.17(1) in order to investigate the evolution of the diamagnetic semiconducting compound FeGa3 into a ferromagnetic metal, which occurs through the electron doping and band structure modifications that result from substitution of Ge for Ga. Heat capacity and magnetization measurements reveal non-Fermi liquid behavior in the vicinity of the transition from a paramagnetic to ferromagnetic ground state, suggesting the presence of a ferromagnetic quantum critical point (FMQCP). We also present the first results of hole doping in this system by the growth of FeGa3- y Zn y single crystals, and electron- and hole doping of the related compound CoGa3 by CoGa3- y Ge y and CoGa3- y Zn y crystal growths, aiming to search for further routes to band structure and charge carrier tuning, thermoelectric optimization, and quantum criticality in this family of compounds. The ability to tune the charge carrier type warrants further investigation of the MGa3 system's thermoelectric properties above room temperature.

  9. Patterning of Perovskite Single Crystals

    KAUST Repository

    Corzo, Daniel

    2017-06-12

    As the internet-of-things hardware integration continues to develop and the requirements for electronics keep diversifying and expanding, the necessity for specialized properties other than the classical semiconductor performance becomes apparent. The success of emerging semiconductor materials depends on the manufacturability and cost as much as on the properties and performance they offer. Solution-based semiconductors are an emerging concept that offers the advantage of being compatible with large-scale manufacturing techniques and have the potential to yield high-quality electronic devices at a lower cost than currently available solutions. In this work, patterns of high-quality MAPbBr3 perovskite single crystals in specific locations are achieved through the modification of the substrate properties and solvent engineering. The fabrication of the substrates involved modifying the surface adhesion forces through functionalization with self-assembled monolayers and patterning them by photolithography processes. Spin coating and blade coating were used to deposit the perovskite solution on the modified silicon substrates. While single crystal perovskites were obtained with the modification of substrates alone, solvent engineering helped with improving the Marangoni flows in the deposited droplets by increasing the contact angle and lowering the evaporation rate, therefore controlling and improving the shape of the grown perovskite crystals. The methodology is extended to other types of perovskites such as the transparent MAPbCl3 and the lead-free MABi2I9, demonstrating the adaptability of the process. Adapting the process to electrode arrays opened up the path towards the fabrication of optoelectronic devices including photodetectors and field-effect transistors, for which the first iterations are demonstrated. Overall, manufacturing and integration techniques permitting the fabrication of single crystalline devices, such as the method in this thesis work, are

  10. Mechanically worked single crystal article

    Energy Technology Data Exchange (ETDEWEB)

    Gell, M. L.; Giamei, A. F.

    1985-07-09

    A single crystal nickel base superalloy component, such as a gas turbine blade is mechanically deformed at elevated temperature to improve the yield strength of a portion which is used at temperatures below 800/sup 0/ C., compared to a portion which is used at a higher temperature. A blade has a root which is deformed by 2-14% at 700/sup 0/-1100/sup 0/ C. and an airfoil which is not deformed. The root yield strength is increased 15-50% while the airfoil creep strength is maintained.

  11. Additive manufacturing of micrometric crystallization vessels and single crystals

    Science.gov (United States)

    Halevi, Oded; Jiang, Hui; Kloc, Christian; Magdassi, Shlomo

    2016-11-01

    We present an all-additive manufacturing method that is performed at mild conditions, for the formation of organic single crystals at specific locations, without any photolithography prefabrication process. The method is composed of two steps; inkjet printing of a confinement frame, composed of a water soluble electrolyte. Then, an organic semiconductor solution is printed within the confinement to form a nucleus at a specific location, followed by additional printing, which led to the growth of a single crystal. The specific geometry of the confinement enables control of the specific locations of the single crystals, while separating the nucleation and crystal growth processes. By this method, we printed single crystals of perylene, which are suitable for the formation of OFETs. Moreover, since this method is based on a simple and controllable wet deposition process, it enables formation of arrays of single crystals at specific locations, which is a prerequisite for mass production of active organic elements on flexible substrates.

  12. Relaxor-PT Single Crystal Piezoelectric Sensors

    OpenAIRE

    Xiaoning Jiang; Jinwook Kim; Kyugrim Kim

    2014-01-01

    Relaxor-PbTiO3 piezoelectric single crystals have been widely used in a broad range of electromechanical devices, including piezoelectric sensors, actuators, and transducers. This paper reviews the unique properties of these single crystals for piezoelectric sensors. Design, fabrication and characterization of various relaxor-PT single crystal piezoelectric sensors and their applications are presented and compared with their piezoelectric ceramic counterparts. Newly applicable fields and futu...

  13. Plate Shape Control Theory and Experiment for 20-high Mill

    Institute of Scientific and Technical Information of China (English)

    Zheng-wen YUAN; Hong XIAO

    2015-01-01

    Roll lfattening theory is an important part of plate shape control theories for 20-high mill. In order to improve the ac-curacy of roll lfattening calculation for 20-high mill, a new and more accurate roll lfattening model was proposed. In this model, the roll barrel was considered as a ifnite length semi-inifnite body. Based on the boundary integral equation method, the numerical solution of the ifnite length semi-inifnite body under the distributed force was obtained and an accurate roll lfattening model was established. Coupled with roll bending model and strip plastic deformation, a new and more accurate plate control model for 20-high mill was established. Moreover, the effects of the ifrst intermediate roll taper angle and taper length were analyzed. The ten-sion distribution calculated by analytical model was consistent with the experimental results.

  14. Synthesis and structural characterization of a single-crystal to single-crystal transformable coordination polymer.

    Science.gov (United States)

    Tian, Yuyang; Allan, Phoebe K; Renouf, Catherine L; He, Xiang; McCormick, Laura J; Morris, Russell E

    2014-01-28

    A single-crystal to single-crystal transformable coordination polymer compound was hydrothermally synthesized. The structural rearrangement is induced by selecting a ligand that contains both strong and weaker coordinating groups. Both hydrated and dehydrated structures were determined by single crystal X-ray analysis.

  15. Ultratough single crystal boron-doped diamond

    Science.gov (United States)

    Hemley, Russell J [Carnegie Inst. for Science, Washington, DC ; Mao, Ho-Kwang [Carnegie Inst. for Science, Washington, DC ; Yan, Chih-Shiue [Carnegie Inst. for Science, Washington, DC ; Liang, Qi [Carnegie Inst. for Science, Washington, DC

    2015-05-05

    The invention relates to a single crystal boron doped CVD diamond that has a toughness of at least about 22 MPa m.sup.1/2. The invention further relates to a method of manufacturing single crystal boron doped CVD diamond. The growth rate of the diamond can be from about 20-100 .mu.m/h.

  16. Adhesion of single crystals on modified surfaces in crystallization fouling

    Science.gov (United States)

    Mayer, Moriz; Augustin, Wolfgang; Scholl, Stephan

    2012-12-01

    In crystallization fouling it has been observed that during a certain initial phase the fouling is formed by a non-uniform layer consisting of a population of single crystals. These single crystals are frequently formed by inverse soluble salts such as CaCO3. During heterogeneous nucleation and heterogeneous growth an interfacial area between the crystal and the heat transfer surface occurs. The development of this interfacial area is the reason for the adhesion of each single crystal and of all individual crystals, once a uniform layer has been built up. The emerging interfacial area is intrinsic to the heterogeneous nucleation of crystals and can be explained by the thermodynamic principle of the minimum of the Gibbs free energy. In this study CaCO3 crystals were grown heterogeneously on untreated and on modified surfaces inside a flow channel. An untreated stainless steel (AISI 304) surface was used as a reference. Following surface modifications were investigated: enameled and electropolished stainless steel as well as diamond-like-carbon based coatings on stainless steel substrate. The adhesion was measured through a novel measurement technique using a micromanipulator to shear off single crystals from the substrate which was fixed to a spring table inside a SEM.

  17. Crystal growth and structural analysis of zirconium sulphoselenide single crystals

    Indian Academy of Sciences (India)

    K R Patel; R D Vaidya; M S Dave; S G Patel

    2008-08-01

    A series of zirconium sulphoselenide (ZrSSe3–, where = 0, 0.5, 1, 1.5, 2, 2.5, 3) single crystals have been grown by chemical vapour transport technique using iodine as a transporting agent. The optimum condition for the growth of these crystals is given. The stoichiometry of the grown crystals were confirmed on the basis of energy dispersive analysis by X-ray (EDAX) and the structural characterization was accomplished by X-ray diffraction (XRD) studies. The crystals are found to possess monoclinic structure. The lattice parameters, volume, particle size and X-ray density have been carried out for these crystals. The effect of sulphur proportion on the lattice parameter, unit cell volume and X-ray density in the series of ZrSSe3– single crystals have been studied and found to decrease in all these parameters with rise in sulphur proportion. The grown crystals were examined under optical zoom microscope for their surface topography study. Hall effect measurements were carried out on grown crystals at room temperature. The negative value of Hall coefficient implies that these crystals are -type in nature. The conductivity is found to decrease with increase of sulphur content in the ZrSSe3– series. The electrical resistivity parallel to c-axis as well as perpendicular to -axis have been carried out in the temperature range 303–423 K. The results obtained are discussed in detail.

  18. Relaxor-PT Single Crystal Piezoelectric Sensors

    Directory of Open Access Journals (Sweden)

    Xiaoning Jiang

    2014-07-01

    Full Text Available Relaxor-PbTiO3 piezoelectric single crystals have been widely used in a broad range of electromechanical devices, including piezoelectric sensors, actuators, and transducers. This paper reviews the unique properties of these single crystals for piezoelectric sensors. Design, fabrication and characterization of various relaxor-PT single crystal piezoelectric sensors and their applications are presented and compared with their piezoelectric ceramic counterparts. Newly applicable fields and future trends of relaxor-PT sensors are also suggested in this review paper.

  19. Defect free single crystal thin layer

    KAUST Repository

    Elafandy, Rami Tarek Mahmoud

    2016-01-28

    A gallium nitride film can be a dislocation free single crystal, which can be prepared by irradiating a surface of a substrate and contacting the surface with an etching solution that can selectively etch at dislocations.

  20. Spray printing of organic semiconducting single crystals.

    Science.gov (United States)

    Rigas, Grigorios-Panagiotis; Payne, Marcia M; Anthony, John E; Horton, Peter N; Castro, Fernando A; Shkunov, Maxim

    2016-11-22

    Single-crystal semiconductors have been at the forefront of scientific interest for more than 70 years, serving as the backbone of electronic devices. Inorganic single crystals are typically grown from a melt using time-consuming and energy-intensive processes. Organic semiconductor single crystals, however, can be grown using solution-based methods at room temperature in air, opening up the possibility of large-scale production of inexpensive electronics targeting applications ranging from field-effect transistors and light-emitting diodes to medical X-ray detectors. Here we demonstrate a low-cost, scalable spray-printing process to fabricate high-quality organic single crystals, based on various semiconducting small molecules on virtually any substrate by combining the advantages of antisolvent crystallization and solution shearing. The crystals' size, shape and orientation are controlled by the sheer force generated by the spray droplets' impact onto the antisolvent's surface. This method demonstrates the feasibility of a spray-on single-crystal organic electronics.

  1. Spray printing of organic semiconducting single crystals

    Science.gov (United States)

    Rigas, Grigorios-Panagiotis; Payne, Marcia M.; Anthony, John E.; Horton, Peter N.; Castro, Fernando A.; Shkunov, Maxim

    2016-11-01

    Single-crystal semiconductors have been at the forefront of scientific interest for more than 70 years, serving as the backbone of electronic devices. Inorganic single crystals are typically grown from a melt using time-consuming and energy-intensive processes. Organic semiconductor single crystals, however, can be grown using solution-based methods at room temperature in air, opening up the possibility of large-scale production of inexpensive electronics targeting applications ranging from field-effect transistors and light-emitting diodes to medical X-ray detectors. Here we demonstrate a low-cost, scalable spray-printing process to fabricate high-quality organic single crystals, based on various semiconducting small molecules on virtually any substrate by combining the advantages of antisolvent crystallization and solution shearing. The crystals' size, shape and orientation are controlled by the sheer force generated by the spray droplets' impact onto the antisolvent's surface. This method demonstrates the feasibility of a spray-on single-crystal organic electronics.

  2. Neutron forward diffraction by single crystal prisms

    Indian Academy of Sciences (India)

    Sohrab Abbas; Apoorva G Wagh; Markus Strobl; Wolfgang Treimer

    2008-11-01

    We have derived analytic expressions for the deflection as well as transmitted fraction of monochromatic neutrons forward diffracted by a single crystal prism. In the vicinity of a Bragg reflection, the neutron deflection deviates sharply from that for an amorphous prism, exhibiting three orders of magnitude greater sensitivity to the incidence angle. We have measured the variation of neutron deflection and transmission across a Bragg reflection, for several single crystal prisms. The results agree well with theory.

  3. Electrically Anisotropic Layered Perovskite Single Crystal

    KAUST Repository

    Li, Ting-You

    2016-04-01

    Organic-inorganic hybrid perovskites (OIHPs), which are promising materials for electronic and optoelectronic applications (1-10), have made into layered organic-inorganic hybrid perovskites (LOIHPs). These LOIHPs have been applied to thin-film transistors, solar cells and tunable wavelength phosphors (11-18). It is known that devices fabricated with single crystal exhibit the superior performance, which makes the growth of large-sized single crystals critical for future device applications (19-23). However, the difficulty in growing large-sized LOIHPs single crystal with superior electrical properties limits their practical applications. Here, we report a method to grow the centimeter-scaled LOIHP single crystal of [(HOC2H4NH3)2PbI4], demonstrating the potentials in mass production. After that, we reveal anisotropic electrical and optoelectronic properties which proved the carrier propagating along inorganic framework. The carrier mobility of in-inorganic-plane (in-plane) devices shows the average value of 45 cm2 V–1 s–1 which is about 100 times greater than the record of LOIHP devices (15), showing the importance of single crystal in device application. Moreover, the LOIHP single crystals show its ultra-short carrier lifetime of 42.7 ps and photoluminescence quantum efficiency (PLQE) of 25.4 %. We expect this report to be a start of LOIHPs for advanced applications in which the anisotropic properties are needed (24-25), and meets the demand of high-speed applications and fast-response applications.

  4. Light Emitting Transistors of Organic Single Crystals

    Science.gov (United States)

    Iwasa, Yoshihiro

    2009-03-01

    Organic light emitting transistors (OLETs) are attracting considerable interest as a novel function of organic field effect transistors (OFETs). Besides a smallest integration of light source and current switching devices, OLETs offer a new opportunity in the fundamental research on organic light emitting devices. The OLET device structure allows us to use organic single crystals, in contrast to the organic light emitting diodes (OLEDs), the research of which have been conducted predominantly on polycrystalline or amorphous thin films. In the case of OFETs, use of single crystals have produced a significant amount of benefits in the studies of pursuit for the highest performance limit of FETs, intrinsic transport mechanism in organic semiconductors, and application of the single crystal transistors. The study on OLETs have been made predominantly on polycrystalline films or multicomponent heterojunctions, and single crystal study is still limited to tetracene [1] and rubrene [2], which are materials with relatively high mobility, but with low photoluminescence efficiency. In this paper, we report fabrication of single crystal OLETs of several kinds of highly luminescent molecules, emitting colorful light, ranging from blue to red. Our strategy is single crystallization of monomeric or oligomeric molecules, which are known to have a very high photoluminescence efficiency. Here we report the result on single crystal LETs of rubrene (red), 4,4'-bis(diphenylvinylenyl)-anthracene (green), 1,4-bis(5-phenylthiophene-2-yl)benzene (AC5) (green), and 1,3,6,8-tetraphenylpyrene (TPPy) (blue), all of which displayed ambipolar transport as well as peculiar movement of voltage controlled movement of recombination zone, not only from the surface of the crystal but also from the edges of the crystals, indicting light confinement inside the crystal. Realization of ambipolar OLET with variety of single crystals indicates that the fabrication method is quite versatile to various light

  5. The growth of sapphire single crystals

    Directory of Open Access Journals (Sweden)

    STEVAN DJURIC

    2001-06-01

    Full Text Available Sapphire (Al2O3 single crystals were grown by the Czochralski technique both in air and argon atmospheres. The conditions for growing sapphire single crystals were calculated by using a combination of Reynolds and Grashof numbers. Acritical crystal diameter dc = 20 mm and the critical rate of rotation wc = 20 rpm were calculated from the hydrodynamics of the melt. The value of the rate of crystal growth was experimentally found to be 3.5 mm/h. According to our previous experiments, it was confirmed that three hours exposures to conc. H3PO4 at 593 K was suitable for chemical polishing. Also, three hours exposure to conc.H3PO4 at 523 K was found to be a suitable etching solution. The lattice parameters a = 0.47573 nm and c = 1.29893 nm were determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

  6. Neutron detection with single crystal organic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Zaitseva, N; Newby, J; Hamel, S; Carman, L; Faust, M; Lordi, V; Cherepy, N; Stoeffl, W; Payne, S

    2009-07-15

    Detection of high-energy neutrons in the presence of gamma radiation background utilizes pulse-shape discrimination (PSD) phenomena in organics studied previously only with limited number of materials, mostly liquid scintillators and single crystal stilbene. The current paper presents the results obtained with broader varieties of luminescent organic single crystals. The studies involve experimental tools of crystal growth and material characterization in combination with the advanced computer modeling, with the final goal of better understanding the relevance between the nature of the organic materials and their PSD properties. Special consideration is given to the factors that may diminish or even completely obscure the PSD properties in scintillating crystals. Among such factors are molecular and crystallographic structures that determine exchange coupling and exciton mobility in organic materials and the impurity effect discussed on the examples of trans-stilbene, bibenzyl, 9,10-diphenylanthracene and diphenylacetylene.

  7. Hybrid gold single crystals incorporating amino acids

    CERN Document Server

    Chen, Linfeng; Weber, Eva; Fitch, Andy N; Pokroy, Boaz

    2016-01-01

    Composite hybrid gold crystals are of profound interest in various research areas ranging from materials science to biology. Their importance is due to their unique properties and potential implementation, for example in sensing or in bio-nanomedicine. Here we report on the formation of hybrid organic-metal composites via the incorporation of selected amino acids histidine, aspartic acid, serine, glutamine, alanine, cysteine, and selenocystine into the crystal lattice of single crystals of gold. We used electron microscopy, chemical analysis and high-resolution synchrotron powder X ray diffraction to examine these composites. Crystal shape, as well as atomic concentrations of occluded amino acids and their impact on the crystal structure of gold, were determined. Concentration of the incorporated amino acid was highest for cysteine, followed by serine and aspartic acid. Our results indicate that the incorporation process probably occurs through a complex interaction of their individual functional groups with ...

  8. Single chirality through crystal grinding

    NARCIS (Netherlands)

    Noorduin, W.L.

    2010-01-01

    The properties of chiral molecules in living organisms can be different for left- and right-handed molecules. Therefore, ways to produce molecules of single handedness are of paramount importance, especially for economical, high yielding processes to synthesize pharmaceutical compounds that must be

  9. The growth of Nd: YAG single crystals

    Directory of Open Access Journals (Sweden)

    ANDREJA VALCIC

    2002-04-01

    Full Text Available Y3Al5O12 doped with 0.8 % wt. Nd (Nd:YAG single crystals were grown by the Czochralski technique under an argon atmosphere. The conditions for growing the Nd: YAG single crystals were calculated by using a combination of Reynolds and Grashof numbers. The critical crystal diameter and the critical rate of rotation were calculated from the hydrodynamics of the melt. The crystal diameter Dc = 1.5 cm remained constant during the crystal growth, while the critical rate of rotation changed from wc = 38 rpm after necking to wc = 13 rpm at the end of the crystal. The value of the rate of crystal growth was experimentally found to be 0.8–1.0 mm/h. According to our previous experiments, it was confirmed that 20 min exposure to conc. H3PO4 at 603 K was suitable for chemical polishing. Also, one-hour exposure to conc. H3PO4 at 493 K was found to be suitable for etching. The lattice parameter a = 1.201 (1 nm was determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

  10. First Single-Crystal Mullite Fibers

    Science.gov (United States)

    1997-01-01

    Ceramic-matrix composites strengthened by suitable fiber additions are being developed for high-temperature use, particularly for aerospace applications. New oxide-based fibers, such as mullite, are particularly desirable because of their resistance to high-temperature oxidative environments. Mullite is a candidate material in both fiber and matrix form. The primary objective of this work was to determine the growth characteristics of single-crystal mullite fibers produced by the laser-heated floating zone method. Directionally solidified fibers with nominal mullite compositions of 3Al2O3 2SiO2 were grown by the laser-heated floating zone method at the NASA Lewis Research Center. SEM analysis revealed that the single-crystal fibers grown in this study were strongly faceted and that the facets act as critical flaws, limiting fiber strength. The average fiber tensile strength is 1.15 GPa at room temperature. The mullite fibers exhibit superior strength retention (80 percent of their room temperature tensile strength at 1450 C). Examined by transmission electron microscopy, these mullite single crystals are free of dislocations, low-angle boundaries, and voids. In addition, they show a high degree of oxygen vacancy ordering. High-resolution digital images from an optical microscope furnish evidence of the formation of a liquid-liquid miscibility gap during crystal growth. These images represent the first experimental evidence of liquid immiscibility for these compositions and temperatures. Continuing investigation with controlled seeding of mullite single crystals is planned.

  11. Friction stir welding of single crystal aluminium

    DEFF Research Database (Denmark)

    Fonda, Richard Warren; Wert, John A.; Reynolds, A.P.

    2007-01-01

    Friction stir welds were prepared in different orientations in an aluminium single crystal. The welds were quenched to preserve the microstructure surrounding the tool and then electron backscattered diffraction was used to reveal the generation of grain boundaries and the evolution of crystallog......Friction stir welds were prepared in different orientations in an aluminium single crystal. The welds were quenched to preserve the microstructure surrounding the tool and then electron backscattered diffraction was used to reveal the generation of grain boundaries and the evolution...

  12. Radiation piezoelectric effect in germanium single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kikoin, I.K.; Kikoin, L.I.; Lazarev, S.D.

    1977-06-01

    Irradiation with ionizing particles of a germanium single crystal and uniaxial deformation at right-angles to the particle beam produced an electric field and a corresponding emf due to the radiation piezoelectric effect. Measurements were carried out when such a single crystal was irradiated with ..cap alpha.. particles and protons. The piezoelectric emf increased linearly with the compressive stress and the ..cap alpha..-particle flux intensity. The emf depended weakly on the particle energy. The observed effect was due to the anisotropy resulting from uniaxial deformation.

  13. Inkjet printing of single-crystal films

    Science.gov (United States)

    Minemawari, Hiromi; Yamada, Toshikazu; Matsui, Hiroyuki; Tsutsumi, Jun'ya; Haas, Simon; Chiba, Ryosuke; Kumai, Reiji; Hasegawa, Tatsuo

    2011-07-01

    The use of single crystals has been fundamental to the development of semiconductor microelectronics and solid-state science. Whether based on inorganic or organic materials, the devices that show the highest performance rely on single-crystal interfaces, with their nearly perfect translational symmetry and exceptionally high chemical purity. Attention has recently been focused on developing simple ways of producing electronic devices by means of printing technologies. `Printed electronics' is being explored for the manufacture of large-area and flexible electronic devices by the patterned application of functional inks containing soluble or dispersed semiconducting materials. However, because of the strong self-organizing tendency of the deposited materials, the production of semiconducting thin films of high crystallinity (indispensable for realizing high carrier mobility) may be incompatible with conventional printing processes. Here we develop a method that combines the technique of antisolvent crystallization with inkjet printing to produce organic semiconducting thin films of high crystallinity. Specifically, we show that mixing fine droplets of an antisolvent and a solution of an active semiconducting component within a confined area on an amorphous substrate can trigger the controlled formation of exceptionally uniform single-crystal or polycrystalline thin films that grow at the liquid-air interfaces. Using this approach, we have printed single crystals of the organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) (ref. 15), yielding thin-film transistors with average carrier mobilities as high as 16.4cm2V-1s-1. This printing technique constitutes a major step towards the use of high-performance single-crystal semiconductor devices for large-area and flexible electronics applications.

  14. Piezoelectricity in Single Crystal of Pentaerythritol Tetranitrate

    Directory of Open Access Journals (Sweden)

    K. Raha

    1991-07-01

    Full Text Available The piezoelectric constants perpendicular to (110 and (001 of single crystal f pentaerythritol tetranitrate (PETN are determined to be (3.2+-0.30x10/sup-13/and (1.5+-0.30x10/sub-13/CN/sub-1/. The charge development on these faces under static loading has been confirmed to be true piezoelectric in origin. The crystal seems to experience a quasi permanent deformation under repeated and successive compression with a very long relaxation time. This gives rise to a unique behaviour of individual crystal of PETN under identical stress condition. Mechanical stress relaxation measurements have also been carried out to provide additional evidence on the uniqueness of the crystal. Dielectric constant of the crystal along the directions perpendicular to (110 and (001 are 3.50+-0.12 and 4.57+-0.17; Young's modulus along the directions are (1.24+- 0.30x10/sub6/g cm/sup-2/ respectively. Single crystals of one cm/sub3/ of PETN develops about 10 V cm/sup-1/ field under a force of 1 kg across (110face.

  15. High Polarization Single Mode Photonic Crystal Microlaser

    Institute of Scientific and Technical Information of China (English)

    CHEN Wei; XING Ming-Xin; ZHOU Wen-Jun; LIU An-Jin; ZHENG Wan-Hua

    2009-01-01

    Generally,dipole mode is a doubly degenerate mode.Theoretical calculations have indicated that the single dipole mode of two-dimensional photonic crystal single point defect cavity shows high polarization property.We present a structure with elongated lattice,which only supports a single y-dipole mode.With this structure we can eliminate the degeneracy,control the lasing action of the cavity and demonstrate the high polarization property of the single dipole mode.In our experiment,the polarization extinction ratio of the y-dipole mode is as high as 51:1.

  16. Microhardness studies of sulfamic acid single crystal

    Science.gov (United States)

    Santhosh Kumar, A.; Joseph, Cyriac; Paulose, Reshmi; R, Rajesh; Joseph, Georgekutty; Louis, Godfrey

    2015-02-01

    Vicker's microhardness study of (100), (010) and (001) faces of a non-linear optical crystal sulfamic acid have been reported. Single crystals of sulfamic acid have been grown by slow evaporation method. The load dependence of the Vickers microhardness of sulfamic acid crystal were investigated and analyzed from the stand point of various theoretical models. Crystal samples in a, b and c-axes exhibit reverse indentation effect which is best described by Meyer's law, Hays-Kendall's approach and proportional specimen resistance (PSR) models. The negative values of load dependent quantities in Hays-Kendall's approach and PSR model suggest that the origin of indentation size effect is associated with the process of relaxation of indentation stresses.

  17. Synthesis of monoclinic zinc diphosphide single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mowles, T.A.

    1978-05-01

    Monoclinic zinc diphosphide is a cheap, plentiful, direct-gap semiconductor with an optimum transition energy for solar absorption. Single crystals were grown from the vapor to be evaluated as a new photovoltaic material. Monoclinic and tetragonal crystal formed within evacuated quartz ampules that were charged with zinc and excess phosphorous and heated in a temperature gradient to give phosphorous pressures from 0.07 to 8.5 atmospheres. The monoclinic form melts incongruently near 990/sup 0/C. The tetragonal form is metastable; its growth is enhanced by impurities but retarded by high phosphorous pressures. The mechanism of the synthesis indicates that a tightly-controlled vapor deposition is possible and that high-quality thin films should form at temperatures from 950 to 990/sup 0/C at pressures below 10 atmospheres. By a modification of the technique, sesquizinc phosphide single crystals were grown for comparison.

  18. Recrystallization of deformed single crystals of iridium

    Energy Technology Data Exchange (ETDEWEB)

    Ermakov, A.V.; Klotsman, S.M.; Pushin, V.G.; Timofeev, A.N.; Kaigorodov, V.N.; Panfilov, P.Y.; Yurchenko, L.I.

    1999-12-31

    The X-ray diffractometric method was used to analyze crystalline textures that appear during rolling of pure single-Ir and annealing of the said crystals in ultrahigh vacuum (UHV) at successively elevating temperatures. Observing alteration of the texture of the deformed pure single-Ir after UHV annealing, the primary recrystallization temperature T{sub 1recr} of pure Ir was found not to exceed 670 K (0.25 T{sub m}).

  19. Ionic conduction of lithium hydride single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Pilipenko, G.I.; Oparin, D.V.; Zhuravlev, N.A.; Gavrilov, F.F.

    1987-09-01

    Using the electrical-conductivity- and NMR-measurement- methods, the ionic-conduction mechanism is established in stoichiometric lithium hydride single crystals. The activation energies of migration of anion- and cation-vacancies and the formation of Schottky-pair defects are determined. They assume that the mechanisms of self-diffusion and conductivity are different in lithium hydride.

  20. Lattice effects in YVO3 single crystal

    NARCIS (Netherlands)

    Marquina, C; Sikora, M; Ibarra, MR; Nugroho, AA; Palstra, TTM

    2005-01-01

    In this paper we report on the lattice effects in the Mott insulator yttrium orthovanadate (YVO3). Linear thermal expansion and magnetostriction experiments have been performed on a single crystal, in the temperature range from 5 K to room temperature. The YVO3 orders antiferromagnetically at T-N =

  1. Antiferromagnetism in chromium alloy single crystals

    DEFF Research Database (Denmark)

    Bjerrum Møller, Hans; Trego, A.L.; Mackintosh, A.R.

    1965-01-01

    The antiferromagnetism of single crystals of dilute alloys of V, Mn and Re in Cr has been studied at 95°K and 300°K by neutron diffraction. The addition of V causes the diffraction peaks to decrease in intensity and move away from (100), while Mn and Re cause them to increase and approach (100) so...

  2. Growth of single-crystal gallium nitride

    Science.gov (United States)

    Clough, R.; Richman, D.; Tietjen, J.

    1970-01-01

    Use of ultrahigh purity ammonia prevents oxygen contamination of GaN during growth, making it possible to grow the GaN at temperatures as high as 825 degrees C, at which point single crystal wafers are deposited on /0001/-oriented sapphire surfaces.

  3. High Field Magnetization of Tb Single Crystals

    DEFF Research Database (Denmark)

    Roeland, L. W.; Cock, G. J.; Lindgård, Per-Anker

    1975-01-01

    The magnetization of Tb single crystals was measured in magnetic fields to 34T along the hard direction at temperature of 1.8, 4.2, 65.5 and 77K, and along with easy direction at 4.2 and 77K. The data are compared with the results of a self-consistent spin wave calculation using a phenomenological...

  4. MAGNETORESISTANCE AND HALL EFFECT IN SINGLE CRYSTALS OF ALUMINUM

    Science.gov (United States)

    ALUMINUM, *SINGLE CRYSTALS, CRYSTALS, HALL EFFECT , IMPURITIES, LOW PRESSURE, MAGNETIC FIELDS, MAGNETIC PROPERTIES, PARTICLE TRAJECTORIES, ELECTRICAL RESISTANCE, SOLID STATE PHYSICS, SURFACE PROPERTIES.

  5. The growth of ruby single crystals

    Directory of Open Access Journals (Sweden)

    ALEKSANDAR GOLUBOVIC

    2005-02-01

    Full Text Available Ruby (Cr:Al2O3 single crystals were grown by the Czochralski technique in an argon atmosphere. The critical crystal diameter dc = 1.0 cm and the critical rate of rotation wc = 20 rpm were calculated by equations of the hydrodynamics of the melt. The rate of crystal growthwas experimentally obtained to be 2.7 mm/h. For chemical polishing, conc. H3PO4 at 593 K for an exposure of 3 hours was determined. Conc. H3PO4 at 523 K for an exposure of 3 h was found to be a suitable etching solution. The lattice parameters a = 0.47627(6 nm and c = 1.301(1 nm were determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

  6. Biomineralization of nanoscale single crystal hydroxyapatite.

    Science.gov (United States)

    Omokanwaye, Tiffany; Wilson, Otto C; Gugssa, Ayelle; Anderson, Winston

    2015-11-01

    The chemical and physical characteristics of nanocrystalline hydroxyapatite particles which formed during the subcutaneous implantation of crab shell in Sprague-Dawley rats were studied using selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM). The initial SAED characterization evidence indicated the presence of an amorphous calcium phosphate phase. The electron dense nanophase particles which formed in the wound healing zone displayed broad diffuse rings which usually indicate a low crystalline order or amorphous phase. High resolution transmission electron microscopy (HRTEM) revealed that these mineralized regions contained discrete single crystal particles less than 5nm in size. Micrographs taken at successively higher magnifications revealed very small nanoparticles with a hexagonal arrangement of ion channels with characteristic spacing of 0.54nm and 0.23nm. This study revealed that single crystal hydroxyapatite nanoparticles consisting of only a few unit cells formed via a biomineralization directed process. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Electroluminescence in BaFCl single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Somaiah, K.; Paracchini, C.

    1987-06-01

    A study of electroluminescence in BaFCl single crystals as a function of temperature is reported. At an excitation voltage of 5 kV, electroluminescent intensity, which is feeble at room temperature, is shown to increase with decreasing temperature. The increase is rapid between 250 K and 175 K and levels off as 80 K is approached. A tentative explanation, in the light of x-ray induced luminescence, is offered. (U.K.).

  8. Secondary particle emission from sapphire single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Minnebaev, K.F., E-mail: minnebaev@mail.ru [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Khvostov, V.V.; Zykova, E.Yu.; Tolpin, K.A. [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Colligon, J.S. [Manchester Metropolitan University, Chester Street, Manchester M1 5GD (United Kingdom); Yurasova, V.E. [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation)

    2015-07-01

    Secondary ion emission from sapphire single crystal has been studied experimentally and by means of computer simulation. The particular oscillations of secondary ion energy spectra and two specific maxima of O{sup +} and Al{sup +} ions were observed under irradiation of (0001) sapphire face by 1 and 10 keV Ar{sup +} ions. We have explained this by the interplay of the charge exchange processes between moving particles and solids. The existence of two maxima in energy spectra of O{sup +} and Al{sup +} secondary ions can be also connected with special features of single-crystal sputtering: the low-energy peak can be formed by random sputtering and the high-energy peak from focusing collisions. In addition some similarity was found between the positions of low-energy maximum in energy spectra of Al{sup +} ions emitted from sapphire and the principal maxima of Al{sup +} ions ejected from the aluminum single crystal. This indicates a possibility to explain the presence of low-energy maximum in energy spectra of secondary ions ejecting from sapphire by emission of Al{sup +} ions from aluminum islands appearing in a number of cases on the sapphire surface due to preferential sputtering of oxygen. These different mechanisms of creating the energy spectra of ions emitted from sapphire should be taken in account.

  9. Biomineralization of nanoscale single crystal hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Omokanwaye, Tiffany [Catholic University of America, BONE/CRAB Lab, Department of Biomedical Engineering, Washington, DC 20064 (United States); Wilson, Otto C., E-mail: wilsono@cua.edu [Catholic University of America, BONE/CRAB Lab, Department of Biomedical Engineering, Washington, DC 20064 (United States); Gugssa, Ayelle; Anderson, Winston [Howard University, Department of Biology, Washington, DC (United States)

    2015-11-01

    The chemical and physical characteristics of nanocrystalline hydroxyapatite particles which formed during the subcutaneous implantation of crab shell in Sprague–Dawley rats were studied using selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM). The initial SAED characterization evidence indicated the presence of an amorphous calcium phosphate phase. The electron dense nanophase particles which formed in the wound healing zone displayed broad diffuse rings which usually indicate a low crystalline order or amorphous phase. High resolution transmission electron microscopy (HRTEM) revealed that these mineralized regions contained discrete single crystal particles less than 5 nm in size. Micrographs taken at successively higher magnifications revealed very small nanoparticles with a hexagonal arrangement of ion channels with characteristic spacing of 0.54 nm and 0.23 nm. This study revealed that single crystal hydroxyapatite nanoparticles consisting of only a few unit cells formed via a biomineralization directed process. - Highlights: • Nanocrystalline particles were formed during in vivo implantation of crab shell using a rat model. • High resolution TEM revealed that nanoparticles were single crystals and less than 5 nm in size. • The relative distance between spots matches the expected values for hydroxyapatite.

  10. Charge transport in single crystal organic semiconductors

    Science.gov (United States)

    Xie, Wei

    Organic electronics have engendered substantial interest in printable, flexible and large-area applications thanks to their low fabrication cost per unit area, chemical versatility and solution processability. Nevertheless, fundamental understanding of device physics and charge transport in organic semiconductors lag somewhat behind, partially due to ubiquitous defects and impurities in technologically useful organic thin films, formed either by vacuum deposition or solution process. In this context, single-crystalline organic semiconductors, or organic single crystals, have therefore provided the ideal system for transport studies. Organic single crystals are characterized by their high chemical purity and outstanding structural perfection, leading to significantly improved electrical properties compared with their thin-film counterparts. Importantly, the surfaces of the crystals are molecularly flat, an ideal condition for building field-effect transistors (FETs). Progress in organic single crystal FETs (SC-FETs) is tremendous during the past decade. Large mobilities ~ 1 - 10 cm2V-1s-1 have been achieved in several crystals, allowing a wide range of electrical, optical, mechanical, structural, and theoretical studies. Several challenges still remain, however, which are the motivation of this thesis. The first challenge is to delineate the crystal structure/electrical property relationship for development of high-performance organic semiconductors. This thesis demonstrates a full spectrum of studies spanning from chemical synthesis, single crystal structure determination, quantum-chemical calculation, SC-OFET fabrication, electrical measurement, photoelectron spectroscopy characterization and extensive device optimization in a series of new rubrene derivatives, motivated by the fact that rubrene is a benchmark semiconductor with record hole mobility ~ 20 cm2V-1s-1. With successful preservation of beneficial pi-stacking structures, these rubrene derivatives form

  11. A nanoporous two-dimensional polymer by single-crystal-to-single-crystal photopolymerization.

    Science.gov (United States)

    Kissel, Patrick; Murray, Daniel J; Wulftange, William J; Catalano, Vincent J; King, Benjamin T

    2014-09-01

    In contrast to the wide number and variety of available synthetic routes to conventional linear polymers, the synthesis of two-dimensional polymers and unambiguous proof of their structure remains a challenge. Two-dimensional polymers-single-layered polymers that form a tiling network in exactly two dimensions-have potential for use in nanoporous membranes and other applications. Here, we report the preparation of a fluorinated hydrocarbon two-dimensional polymer that can be exfoliated into single sheets, and its characterization by high-resolution single-crystal X-ray diffraction analysis. The procedure involves three steps: preorganization in a lamellar crystal of a rigid monomer bearing three photoreactive arms, photopolymerization of the crystalline monomers by [4 + 4] cycloaddition, and isolation of individual two-dimensional polymer sheets. This polymer is a molecularly thin (~1 nm) material that combines precisely defined monodisperse pores of ~9 Å with a high pore density of 3.3 × 10(13) pores cm(-2). Atomic-resolution single-crystal X-ray structures of the monomer, an intermediate dimer and the final crystalline two-dimensional polymer were obtained and prove the single-crystal-to-single-crystal nature and molecular precision of the two-dimensional photopolymerization.

  12. Perpetually self-propelling chiral single crystals.

    Science.gov (United States)

    Panda, Manas K; Runčevski, Tomče; Husain, Ahmad; Dinnebier, Robert E; Naumov, Panče

    2015-02-11

    When heated, single crystals of enantiomerically pure D- and L-pyroglutamic acid (PGA) are capable of recurring self-actuation due to rapid release of latent strain during a structural phase transition, while the racemate is mechanically inactive. Contrary to other thermosalient materials, where the effect is accompanied by crystal explosion due to ejection of debris or splintering, the chiral PGA crystals respond to internal strain with unprecedented robustness and can be actuated repeatedly without deterioration. It is demonstrated that this superelasticity is attained due to the low-dimensional hydrogen-bonding network which effectively accrues internal strain to elicit propulsion solely by elastic deformation without disintegration. One of the two polymorphs (β) associated with the thermosalient phase transition undergoes biaxial negative thermal expansion (αa = -54.8(8) × 10(-6) K(-1), αc = -3.62(8) × 10(-6) K(-1)) and exceptionally large uniaxial thermal expansion (αb = 303(1) × 10(-6) K(-1)). This second example of a thermosalient solid with anomalous expansion indicates that the thermosalient effect can be expected for first-order phase transitions in soft crystals devoid of an extended 3D hydrogen-bonding network that undergo strongly anisotropic thermal expansion around the phase transition.

  13. Electrical conductivity of sulfamic acid single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Varughese, G. [Department of Physics, Catholicate College, Pathanamthitta, Kerala (India); Iype, L. [School of Pure and Applied Physics, Mahatma Gandhi Unniversity, Kottayam, Kerala (India); Rajesh, R. [Department of Physics, N S S College, Manjeri, Malappuram, Kerala (India); Joseph, G. [Department of Physics, Sacred Heart College, Thevara, Cochin, Kerala (India); Louis, G. [Department of Physics, Cochin University of Science and Technology, Cochin, Kerala (India); Santhosh Kumar, A.

    2010-08-15

    Single crystals of sulfamic acid have been grown by the method of slow evaporation at constant temperature. DC electrical conductivity was measured in the temperature range 300 - 440 K along a, b and c-axes. Conductivity measurements show slope change near 330 K and 410 K. The slope change observed around 330 K may be attributed as due to a phase transition which has been well supported by the DSC and DTA measurements. Slope change observed around 410 K is attributed as the onset of the thermal decomcoposition as evidenced by TGA curve. TGA studies show the crystal is very stable up to 440 K. Activation energies for the conduction process are calculated for all measured crystallographic directions. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Direct shear of olivine single crystals

    Science.gov (United States)

    Tielke, Jacob A.; Zimmerman, Mark E.; Kohlstedt, David L.

    2016-12-01

    Knowledge of the strengths of the individual dislocation slip systems in olivine is fundamental to understanding the flow behavior and the development of lattice-preferred orientation in olivine-rich rocks. The most direct measurements of the strengths of individual slip systems are from triaxial compression experiments on olivine single crystals. However, such experiments only allow for determination of flow laws for two of the four dominant slip systems in olivine. In order to measure the strengths of the (001)[100] and (100)[001] slip systems independently, we performed deformation experiments on single crystals of San Carlos olivine in a direct shear geometry. Experiments were carried out at temperatures of 1000 ° to 1300 °C, a confining pressure of 300 MPa, shear stresses of 60 to 334 MPa, and resultant shear strain rates of 7.4 × 10-6 to 2.1 × 10-3 s-1. At high-temperature (≥1200 °C) and low-stress (≤200 MPa) conditions, the strain rate of crystals oriented for direct shear on either the (001)[100] or the (100)[001] slip system follows a power law relationship with stress, whereas at lower temperatures and higher stresses, strain rate depends exponentially on stress. The flow laws derived from the mechanical data in this study are consistent with a transition from the operation of a climb-controlled dislocation mechanism during power-law creep to the operation of a glide-controlled dislocation mechanism during exponential creep. In the climb-controlled regime, crystals oriented for shear on the (001)[100] slip system are weaker than crystals orientated for shear on the (100)[001] slip system. In contrast, in the glide-controlled regime the opposite is observed. Extrapolation of flow laws determined for crystals sheared in orientations favorable for slip on these two slip systems to upper mantle conditions reveals that the (001)[100] slip system is weaker at temperatures and stresses that are typical of the asthenospheric mantle, whereas the (100

  15. Fabrication of crystals from single metal atoms.

    Science.gov (United States)

    Barry, Nicolas P E; Pitto-Barry, Anaïs; Sanchez, Ana M; Dove, Andrew P; Procter, Richard J; Soldevila-Barreda, Joan J; Kirby, Nigel; Hands-Portman, Ian; Smith, Corinne J; O'Reilly, Rachel K; Beanland, Richard; Sadler, Peter J

    2014-05-27

    Metal nanocrystals offer new concepts for the design of nanodevices with a range of potential applications. Currently the formation of metal nanocrystals cannot be controlled at the level of individual atoms. Here we describe a new general method for the fabrication of multi-heteroatom-doped graphitic matrices decorated with very small, ångström-sized, three-dimensional (3D)-metal crystals of defined size. We irradiate boron-rich precious-metal-encapsulated self-spreading polymer micelles with electrons and produce, in real time, a doped graphitic support on which individual osmium atoms hop and migrate to form 3D-nanocrystals, as small as 15 Å in diameter, within 1 h. Crystal growth can be observed, quantified and controlled in real time. We also synthesize the first examples of mixed ruthenium-osmium 3D-nanocrystals. This technology not only allows the production of ångström-sized homo- and hetero-crystals, but also provides new experimental insight into the dynamics of nanocrystals and pathways for their assembly from single atoms.

  16. Growth and characterization of propyl-para-hydroxybenzoate single crystals

    Indian Academy of Sciences (India)

    N Karunagaran; P Ramasamy; R Perumal Ramasamy

    2014-10-01

    Single crystals of propyl--hydroxybenzoate have been grown by slow evaporation solution technique. The structure of the compound was confirmed by FT–IR, FT–Raman spectroscopy and single crystal X-ray diffraction studies. The crystalline perfection of the grown single crystals has been analysed by high resolution X-ray diffraction measurements. Optical properties of the grown single crystals were studied by UV–Vis NIR spectrum. The luminescence behaviour of the single crystal has been analysed by photoluminescence analysis and found maximum luminescence in the lower wavelength region. A simple interferometric technique was used for measuring birefringence of the crystal. The laser damage threshold of the crystal is 1.3 GW/cm2. The mechanical strength of the grown crystal is measured using Vickers microhardness tester. The dielectric properties have been investigated.

  17. The new single crystal diffractometer SC3

    Energy Technology Data Exchange (ETDEWEB)

    Schefer, J.; Koch, M.; Keller, P.; Fischer, S.; Thut, R. [Lab. for Neutron Scattering ETH Zurich, Zurich (Switzerland) and Paul Scherrer Institute, Villigen (Switzerland)

    1996-11-01

    Single crystal diffraction is a powerful method for the determination of precise structure parameters, superlattices, stress. Neutron single crystal diffraction gives additionally to X-rays information on magnetic structures, both commensurate and incommensurate, hydrogen positions, hydrogen bonding behavior and accurate bondlengths, e.g. important in cuprates. The method is therefore especially powerful if combined with X-ray diffraction results. The new instrument at SINQ has been designed for inorganic materials and is positioned at a thermal beam tube, pointing on a water scatterer. This scatterer is presently operating with H{sub 2}O at ambient temperature, but a change to another medium at different temperature is possible. The instrument will be equipped with three area detectors, moving at fixed difference in 2{Theta}. each detector may be individually moved around a vertical circle (tilting angle {gamma}), allowing to use not only 4-circle geometry in the temperature range from 1.5 to 380 K, but also any equipment from a dilution refrigerator (7 mK) to a heavy magnet. A high temperature furnace for 4-circle geometry is foreseen as a future option. (author) 6 figs., 1 tab., 7 refs.

  18. Growth of single crystals of BaFe12O19 by solid state crystal growth

    Science.gov (United States)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-10-01

    Single crystals of BaFe12O19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe12O19 are buried in BaFe12O19+1 wt% BaCO3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe12O19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe12O19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth.

  19. Load Relaxation of Olivine Single Crystals

    Science.gov (United States)

    Cooper, R. F.; Stone, D. S.; Plookphol, T.

    2016-12-01

    Single crystals of ferromagnesian olivine (San Carlos, AZ, peridot; Fo90-92) have been deformed in both uniaxial creep and load relaxation under conditions of ambient pressure, T = 1500ºC and pO2 = 10-10 atm; creep stresses were in the range 40 ≤ σ1 (MPa) ≤ 220. The crystals were oriented such that the applied stress was parallel to [011]c, which promotes single slip on the slowest slip system in olivine, (010)[001]. The creep rates at steady state match well the results of earlier investigators, as does the stress sensitivity (a power-law exponent of n = 3.6). Dislocation microstructures, including spatial distribution of low-angle (subgrain) boundaries, additionally confirm previous investigations. Inverted primary creep (an accelerating strain rate with an increase in stress) was observed. Load-relaxation, however, produced a singular response—a single hardness curve—regardless of the magnitude of creep stress or total accumulated strain preceding relaxation. The log-stress v. log-strain rate data from load-relaxation and creep experiments overlap to within experimental error. The load-relaxation behavior is distinctly different that that described for other crystalline solids, where the flow stress is affected strongly by work hardening such that a family of distinct hardness curves is generated, which are related by a scaling function. The response of olivine for the conditions studied, thus, indicates flow that is rate-limited by dislocation glide, reflecting specifically a high intrinsic lattice resistance (Peierls stress).

  20. Vibration-assisted machining of single crystal

    Science.gov (United States)

    Zahedi, S. A.; Roy, A.; Silberschmidt, V. V.

    2013-07-01

    Vibration-assisted machining offers a solution to expanding needs for improved machining, especially where accuracy and precision are of importance, such as in micromachining of single crystals of metals and alloys. Crystallographic anisotropy plays a crucial role in determining on overall response to machining. In this study, we intend to address the matter of ultra-precision machining of material at the micron scale using computational modelling. A hybrid modelling approach is implemented that combines two discrete schemes: smoothed particle hydrodynamics and continuum finite elements. The model is implemented in a commercial software ABAQUS/Explicit employing a user-defined subroutine (VUMAT) and used to elucidate the effect of crystallographic anisotropy on a response of face centred cubic (f.c.c.) metals to machining.

  1. Method of Making Lightweight, Single Crystal Mirror

    Science.gov (United States)

    Bly, Vincent T. (Inventor)

    2015-01-01

    A method of making a mirror from a single crystal blank may include fine grinding top and bottom surfaces of the blank to be parallel. The blank may then be heat treated to near its melting temperature. An optical surface may be created on an optical side of the blank. A protector may be bonded to the optical surface. With the protector in place, the blank may be light weighted by grinding a non-optical surface of the blank using computer controlled grinding. The light weighting may include creating a structure having a substantially minimum mass necessary to maintain distortion of the mirror within a preset limit. A damaged layer of the non-optical surface caused by light weighting may be removed with an isotropic etch and/or repaired by heat treatment. If an oxide layer is present, the entire blank may then be etched using, for example, hydrofluoric acid. A reflecting coating may be deposited on the optical surface.

  2. Piezoresistance measurement on single crystal silicon nanowires

    Science.gov (United States)

    Toriyama, Toshiyuki; Funai, Daisuke; Sugiyama, Susumu

    2003-01-01

    A p-type single crystal silicon nanowire bridge and a four-terminal nanowire element were fabricated by electron-beam direct writing. The piezoresistance was investigated in order to demonstrate the usefulness of these sensing elements as mechanical sensors. The longitudinal piezoresistance coefficient πl[110] was found to be 38.7×10-11 Pa-1 at a surface impurity concentration of Ns=9×1019cm-3 for the nanowire bridge. The shear piezoresistance coefficient π44 was found to be 77.4×10-11 Pa-1 at Ns=9×1019 cm-3 for the four-terminal nanowire element. These values are 54.8% larger than the values obtained from p+ diffused piezoresistors, which are used in conventional mechanical sensors.

  3. Development of novel growth methods for halide single crystals

    Science.gov (United States)

    Yokota, Yuui; Kurosawa, Shunsuke; Shoji, Yasuhiro; Ohashi, Yuji; Kamada, Kei; Yoshikawa, Akira

    2017-03-01

    We developed novel growth methods for halide scintillator single crystals with hygroscopic nature, Halide micro-pulling-down [H-μ-PD] method and Halide Vertical Bridgman [H-VB] method. The H-μ-PD method with a removable chamber system can grow a single crystal of halide scintillator material with hygroscopicity at faster growth rate than the conventional methods. On the other hand, the H-VB method can grow a large bulk single crystal of halide scintillator without a quartz ampule. CeCl3, LaBr3, Ce:LaBr3 and Eu:SrI2 fiber single crystals could be grown by the H-μ-PD method and Eu:SrI2 bulk single crystals of 1 and 1.5 inch in diameter could be grown by the H-VB method. The grown fiber and bulk single crystals showed comparable scintillation properties to the previous reports using the conventional methods.

  4. Piezoelectric single crystals for ultrasonic transducers in biomedical applications

    Science.gov (United States)

    Zhou, Qifa; Lam, Kwok Ho; Zheng, Hairong; Qiu, Weibao; Shung, K. Kirk

    2014-01-01

    Piezoelectric single crystals, which have excellent piezoelectric properties, have extensively been employed for various sensors and actuators applications. In this paper, the state–of–art in piezoelectric single crystals for ultrasonic transducer applications is reviewed. Firstly, the basic principles and design considerations of piezoelectric ultrasonic transducers will be addressed. Then, the popular piezoelectric single crystals used for ultrasonic transducer applications, including LiNbO3 (LN), PMN–PT and PIN–PMN–PT, will be introduced. After describing the preparation and performance of the single crystals, the recent development of both the single–element and array transducers fabricated using the single crystals will be presented. Finally, various biomedical applications including eye imaging, intravascular imaging, blood flow measurement, photoacoustic imaging, and microbeam applications of the single crystal transducers will be discussed. PMID:25386032

  5. Single crystal growth and anisotropic crystal-fluid interface tension in soft colloidal systems

    NARCIS (Netherlands)

    Nguyen, V.D.; Hu, Z.; Schall, P.

    2011-01-01

    We measure the anisotropy of the crystal-fluid interfacial free energy in soft colloidal systems. A temperature gradient is used to direct crystal nucleation and control the growth of large single crystals in order to achieve well-equilibrated crystal-fluid interfaces. Confocal microscopy is used to

  6. Functionalizing single crystals: incorporation of nanoparticles inside gel-grown calcite crystals.

    Science.gov (United States)

    Liu, Yujing; Yuan, Wentao; Shi, Ye; Chen, Xiaoqiang; Wang, Yong; Chen, Hongzheng; Li, Hanying

    2014-04-14

    Synthetic single crystals are usually homogeneous solids. Biogenic single crystals, however, can incorporate biomacromolecules and become inhomogeneous solids so that their properties are also extrinsically regulated by the incorporated materials. The discrepancy between the properties of synthetic and biogenic single crystals leads to the idea to modify the internal structure of synthetic crystals to achieve nonintrinsic properties by incorporation of foreign material. Intrinsically colorless and diamagnetic calcite single crystals are turned into colored and paramagnetic solids, through incorporation of Au and Fe3O4 nanoparticles without significantly disrupting the crystalline lattice of calcite. The crystals incorporate the nanoparticles and gel fibers when grown in agarose gel media containing the nanoparticles, whereas the solution-grown crystals do not. As such, our work extends the long-history gel method for crystallization into a platform to functionalize single-crystalline materials.

  7. Piezoelectric single crystals for ultrasonic transducers in biomedical applications

    OpenAIRE

    Zhou, Qifa; Lam, Kwok Ho; Zheng, Hairong; Qiu, Weibao; Shung, K. Kirk

    2014-01-01

    Piezoelectric single crystals, which have excellent piezoelectric properties, have extensively been employed for various sensors and actuators applications. In this paper, the state–of–art in piezoelectric single crystals for ultrasonic transducer applications is reviewed. Firstly, the basic principles and design considerations of piezoelectric ultrasonic transducers will be addressed. Then, the popular piezoelectric single crystals used for ultrasonic transducer applications, including LiNbO...

  8. Ultraviolet Photoelectric Effect in ZrO2 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    XING Jie; WANG Xu; ZHAO Kun; LI Jie; JIN Kui-Juan; HE Meng; ZHENG Dong-Ning; L(U) Hui-Bin

    2007-01-01

    Nanosecond photoelectric effect is observed in a ZrO2 single crystal at ambient temperature for the first time.The rise time is 20ns and the full width at half maximum is about 30ns for the photovoltaic pulse when the wafer surface of the ZrO2 single crystal is irradiated by 248nm KrF laser pulses. The experimental results show that ZrO2 single crystals may be a potential candidate in UV photodetectors.

  9. Volume reflection of ultrarelativistic particles in single crystals

    Directory of Open Access Journals (Sweden)

    V. A. Maisheev

    2007-08-01

    Full Text Available An analytical description of volume reflection of charged ultrarelativistic particles in bent single crystals is considered. The relation describing the angle of volume reflection as a function of the transversal energy is obtained. Different angle distributions of the scattered protons in single crystals are found. Results of calculations for 400 GeV protons scattered by the silicon single crystal are presented.

  10. Composite single crystal silicon scan mirror substrates Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Single crystal silicon is a desirable mirror substrate for scan mirrors in space telescopes. As diameters of mirrors become larger, existing manufacturing...

  11. Cryogenic Fluid Transfer Components Using Single Crystal Piezoelectric Actuators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Cryogenic fluid transfer components using single crystal piezoelectric actuators are proposed to enable low thermal mass, minimal heat leak, low power consumption...

  12. Cryogenic Fluid Transfer Components Using Single Crystal Piezoelectric Actuators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Cryogenic fluid transfer components using single crystal piezoelectric actuators are proposed to enable low thermal mass, minimal heat leak, low power consumption...

  13. Ultratough CVD single crystal diamond and three dimensional growth thereof

    Science.gov (United States)

    Hemley, Russell J [Washington, DC; Mao, Ho-kwang [Washington, DC; Yan, Chih-shiue [Washington, DC

    2009-09-29

    The invention relates to a single-crystal diamond grown by microwave plasma chemical vapor deposition that has a toughness of at least about 30 MPa m.sup.1/2. The invention also relates to a method of producing a single-crystal diamond with a toughness of at least about 30 MPa m.sup.1/2. The invention further relates to a process for producing a single crystal CVD diamond in three dimensions on a single crystal diamond substrate.

  14. Growth morphology and structural characteristic of C70single crystals

    Institute of Scientific and Technical Information of China (English)

    周维亚; 解思深; 吴源; 常保和; 王刚; 钱露茜

    1999-01-01

    Large size C70 single crystals with the dimension of more than 5 mm are grown from the vapor phase by controlling nucleation. X-ray diffraction and electron diffraction confirm that in the C70 single crystal a phase of the hexagonal close-packed (hcp) structure coexists with a minor face-center-cubic (fcc) phase at room temperature. The morphologies and their formation mechanism of the C70 single crystals are investigated by means of scanning electron microscopy and optical microscopy. The influence of growth conditions on the morphologies of C70 single crystals is discussed.

  15. Microcapillary flow behavior of magnetic nanofluids in the presence of plate shaped bentonite particles

    Science.gov (United States)

    Parmar, Mayur; Virpura, Hiral; Patel, Rajesh

    2013-04-01

    Plate shaped bentonite particles of size ˜600 nm and thickness ˜2 nm are dispersed in a magnetic nanofluid. Magnetic field dependent flow behavior of this composite suspension is studied using a horizontal microcapillary placed between the poles of an electromagnet. The plate shaped bentonite particle produces extra hindrance to the flow under the application of moderate magnetic field and produces an enhanced magnetoviscous effect. 75% volume concentration of bentonite produces eight times larger change in magnetic field dependent viscosity than does the pure magnetic nanofluid. Hindrance to the flow is due to the chain like structure of magnetic nanoparticles, tumbling and rotational motion of bentonite particles and interaction between magnetic and bentonite particles. The field-induced structures are also observed using an optical microscope. Results offer several advantages over the inverse MR effect as well as to study the motion of biological cells and tissues under the effect of magnetic field.

  16. Employing a cylindrical single crystal in gas-surface dynamics

    NARCIS (Netherlands)

    Hahn, C.; Shan, J.; Liu, Y.; Berg, van den O.; Kleijn, A.W.; Juurlink, L.B.F.

    2012-01-01

    We describe the use of a polished, hollow cylindrical nickel single crystal to study effects of step edges on adsorption and desorption of gas phase molecules. The crystal is held in an ultra-high vacuum apparatus by a crystal holder that provides axial rotation about a [100] direction, and a crysta

  17. Microcapillary flow behavior of magnetic nanofluids in the presence of plate shaped bentonite particles

    Energy Technology Data Exchange (ETDEWEB)

    Parmar, Mayur; Virpura, Hiral [Department of Physics, Bhavnagar University, Bhavnagar 364001, GJ (India); Patel, Rajesh, E-mail: rjp@bhavuni.edu [Department of Physics, Bhavnagar University, Bhavnagar 364001, GJ (India); Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States)

    2013-04-15

    Plate shaped bentonite particles of size ∼600 nm and thickness ∼2 nm are dispersed in a magnetic nanofluid. Magnetic field dependent flow behavior of this composite suspension is studied using a horizontal microcapillary placed between the poles of an electromagnet. The plate shaped bentonite particle produces extra hindrance to the flow under the application of moderate magnetic field and produces an enhanced magnetoviscous effect. 75% volume concentration of bentonite produces eight times larger change in magnetic field dependent viscosity than does the pure magnetic nanofluid. Hindrance to the flow is due to the chain like structure of magnetic nanoparticles, tumbling and rotational motion of bentonite particles and interaction between magnetic and bentonite particles. The field-induced structures are also observed using an optical microscope. Results offer several advantages over the inverse MR effect as well as to study the motion of biological cells and tissues under the effect of magnetic field. -- Highlights: ► Dispersed plate shaped bentonite particles in magnetic fluids to study capillary viscosity. ► Increased viscosity is due to the hindrance to the rotation of the bentonite particles. ► Increase in viscosity is five times larger for bentonite particles than the pure magnetic fluids. ► This is a new kind of magnetoviscous effect, dispersing anisotropic particles in magnetic fluids.

  18. Hot Corrosion of Coated Single Crystal Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Simms, N. J.; Encinas-Oropesa, A.; Nicholls, J.R. [Cranfield University, Power Generation Technology Centre, Cranfield, Beds, MK43 0AL (United Kingdom)

    2004-07-01

    Gas turbines are at the heart of many modern power systems, with combined cycle power generation utilising natural gas being an effective way of reducing environmental emissions compared to conventional pulverized coal fired plants. The development of gas turbine technology has been focused on increasing its efficiency. However, the lives of the hot gas path components within these gas turbines are also critical to the viability of the power systems. Single crystal superalloys have been developed for use with clean fuel/air but are now being used in industrial gas turbines that may need to run with dirtier fuel/air. Indeed, gas turbine based power systems are being evaluated in which solid fuels (e.g. coal and/or biomass) are gasified to produce fuel gases, which introduces the potential for significant corrosive and erosive damage to gas turbine blades and vanes. The performance of these materials, with coatings, has to be determined before they can be used with confidence in dirtier fuel environments. This paper reports results from a series of laboratory tests carried out using the 'deposit replenishment' technique to investigate the sensitivity of candidate materials to exposure conditions anticipated in such gas turbines. The materials investigated have included CMSX-4 and SC{sup 2}-B (both bare and with Pt-Al and Amdry 997 coatings) as well as conventional nickel based superalloys such as IN738LC for comparison. The exposure conditions within the laboratory tests have covered ranges of SO{sub x} (50 and 500 vpm) and HCl (0 and 500 vpm) in air, as well as 4/1 (Na/K){sub 2}SO{sub 4} deposits, with deposition fluxes of 1.5, 5 and 15 {mu}g/cm{sup 2}/h, for periods of up to 500 hours at 700 and 900 deg. C. Data on the performance of materials has been obtained using dimensional metrology: pre-exposure contact measurements and post-exposure measurements of features on polished cross-sections. These measurement methods allow distributions of damage data to

  19. Mesoporous zeolite and zeotype single crystals synthesized in fluoride media

    DEFF Research Database (Denmark)

    Egeblad, Kresten; Kustova, Marina; Klitgaard, Søren Kegnæs

    2007-01-01

    We report the synthesis and characterization of a series of new mesoporous zeolite and zeotype materials made available by combining new and improved procedures for directly introducing carbon into reaction mixtures with the fluoride route for conventional zeolite synthesis. The mesoporous...... characterized by XRPD, SEM, TEM and N-2 physisorption measurements. For the zeolite materials it A as found that mesoporous MFI and MEL structured single crystals could indeed be crystallized from fluoride media using an improved carbon-templating approach. More importantly, it was found that mesoporous BEA......-type single crystals could be crystallized from fluoride media by a newly developed procedure presented here. Thus, we here present the only known route to mesoporous BEA-type single crystals, since crystallization of this framework structure from basic media is known to give only nanosized crystals...

  20. Optical characterization of ferroelectric glycinium phosphite single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Perumal, R.; Senthil Kumar, K. [Crystal Growth Centre, Anna University, Sardar Patel Road, Chennai, Tamil Nadu 600025 (India); Moorthy Babu, S., E-mail: babu@annauniv.ed [Crystal Growth Centre, Anna University, Sardar Patel Road, Chennai, Tamil Nadu 600025 (India); Bhagavannarayana, G. [Crystal Growth and Crystallography Section, National Physical Laboratory, CSIR, Dr. K.S. Krishnan Marg, New Delhi 110012 (India)

    2010-02-04

    Single crystals of glycinium phosphite (GPI) were grown by isothermal evaporation and conventional temperature-lowering techniques. Single crystal and powder X-ray diffraction analysis confirm the monoclinic structure of the as grown crystals. The structural perfection of the as grown crystal was determined through HRXRD analysis. FTIR and Raman analysis revealed the functional groups present in the grown crystals. The optical absorption of the grown crystal was analyzed and the refractive index values for different wavelengths were measured by prism coupling technique. Thermal stability, melting temperature and phase transition temperature of the as grown crystals were identified from TGA/DSC analysis. The dielectric impedance analysis indicates the continuous phase transition nature of the grown crystals. The mechanical strength and hardening co-efficient were determined from Vicker's microhardness measurements for different loads with constant dwell time. The growth mechanism and the defects were analyzed through chemical etching analysis from various crystallographic planes and etching periods.

  1. Oxygen diffusion in single crystal barium titanate.

    Science.gov (United States)

    Kessel, Markus; De Souza, Roger A; Martin, Manfred

    2015-05-21

    Oxygen diffusion in cubic, nominally undoped, (100) oriented BaTiO3 single crystals has been studied by means of (18)O2/(16)O2 isotope exchange annealing and subsequent determination of the isotope profiles in the solid by time-of-flight secondary ion mass spectrometry (ToF-SIMS). Experiments were carried out as a function of temperature 973 coefficient ks*, the space-charge potential Φ0 and the bulk diffusion coefficient D*(∞). Analysis of the temperature and oxygen activity dependencies of D*(∞) and Φ0 yields a consistent picture of both the bulk and the interfacial defect chemistry of BaTiO3. Values of the oxygen vacancy diffusion coefficient DV extracted from measured D*(∞) data are compared with literature data; consequently a global expression for the vacancy diffusivity in BaTiO3 for the temperature range 466 < T/K < 1273 is obtained, with an activation enthalpy of vacancy migration, ΔHmig,V = (0.70 ± 0.04) eV.

  2. Thermomechanical fatigue in single crystal superalloys

    Directory of Open Access Journals (Sweden)

    Moverare Johan J.

    2014-01-01

    Full Text Available Thermomechanical fatigue (TMF is a mechanism of deformation which is growing in importance due to the efficiency of modern cooling systems and the manner in which turbines and associated turbomachinery are now being operated. Unfortunately, at the present time, relatively little research has been carried out particularly on TMF of single crystal (SX superalloys, probably because the testing is significantly more challenging than the more standard creep and low cycle fatigue (LCF cases; the scarcity and relative expense of the material are additional factors. In this paper, the authors summarise their experiences on the TMF testing of SX superalloys, built up over several years. Emphasis is placed upon describing: (i the nature of the testing method, the challenges involved in ensuring that an given testing methodology is representative of engine conditions (ii the behaviour of a typical Re-containing second generation alloy such as CMSX-4, and its differing performance in out-of-phase/in-phase loading and crystallographic orientation and (iii the differences in behaviour displayed by the Re-containing alloys and new Re-free variants such as STAL15. It is demonstrated that the Re-containing superalloys are prone to different degradation mechanisms involving for example microtwinning, TCP precipitation and recrystallisation. The performance of STAL15 is not too inferior to alloys such as CMSX-4, suggesting that creep resistance itself does not correlate strongly with resistance to TMF. The implications for alloy design efforts are discussed.

  3. Excitonic polaritons of zinc diarsenide single crystals

    Science.gov (United States)

    Syrbu, N. N.; Stamov, I. G.; Zalamai, V. V.; Dorogan, A.

    2017-02-01

    Excitonic polaritons of ZnAs2 single crystals had been investigated. Parameters of singlet excitons with D2bar(z) symmetry and orthoexcitons 2D1bar(y)+D2bar(x) had been determined. Spectral dependencies of ordinary and extraordinary dispersion of refractive index had been calculated using interferential reflection and transmittance spectra. It was shown, that A excitonic series were due to hole (V1) and electron (C1) bands. The values of effective masses of electrons (mc*=0.10 m0) and holes (mv1*=0.89 m0) had been estimated. It was revealed that the hole mass mv1* changes from 1.03 m0 to 0.55 m0 at temperature increasing from 10 K up to 230 K and that the electron mass mc* does not depend on temperature. The integral absorption A (eV cm-1) of the states n=1, 2 and 3 of D2bar(z) excitons depends on the An≈n-3 equality, which it is characteristic for S-type excitonic functions. Temperature dependences of the integral absorption of ground states for D2bar(z) and D2bar(D) excitons differ. The ground states of B and C excitons formed by V3 - C1 and V4 - C1 bands and its parameters had been determined.

  4. Growth and Characterization on PMN-PT-Based Single Crystals

    Directory of Open Access Journals (Sweden)

    Jian Tian

    2014-07-01

    Full Text Available Lead magnesium niobate—lead titanate (PMN-PT single crystals have been successfully commercialized in medical ultrasound imaging. The superior properties of PMN-PT crystals over the legacy piezoelectric ceramics lead zirconate titanate (PZT enabled ultrasound transducers with enhanced imaging (broad bandwidth and improved sensitivity. To obtain high quality and relatively low cost single crystals for commercial production, PMN-PT single crystals were grown with modified Bridgman method, by which crystals were grown directly from stoichiometric melt without flux. For ultrasound imaging application, [001] crystal growth is essential to provide uniform composition and property within a crystal plate, which is critical for transducer performance. In addition, improvement in crystal growth technique is under development with the goals of improving the composition homogeneity along crystal growth direction and reducing unit cost of crystals. In recent years, PIN-PMN-PT single crystals have been developed with higher de-poling temperature and coercive field to provide improved thermal and electrical stability for transducer application.

  5. Single crystal micromechanical resonator and fabrication methods thereof

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, Roy H.; Friedmann, Thomas A.; Homeijer, Sara Jensen; Wiwi, Michael; Hattar, Khalid Mikhiel; Clark, Blythe; Bauer, Todd; Van Deusen, Stuart B.

    2016-12-20

    The present invention relates to a single crystal micromechanical resonator. In particular, the resonator includes a lithium niobate or lithium tantalate suspended plate. Also provided are improved microfabrication methods of making resonators, which does not rely on complicated wafer bonding, layer fracturing, and mechanical polishing steps. Rather, the methods allow the resonator and its components to be formed from a single crystal.

  6. Single crystal micromechanical resonator and fabrication methods thereof

    Science.gov (United States)

    Olsson, Roy H.; Friedmann, Thomas A.; Homeijer, Sara Jensen; Wiwi, Michael; Hattar, Khalid Mikhiel; Clark, Blythe; Bauer, Todd; Van Deusen, Stuart B.

    2016-12-20

    The present invention relates to a single crystal micromechanical resonator. In particular, the resonator includes a lithium niobate or lithium tantalate suspended plate. Also provided are improved microfabrication methods of making resonators, which does not rely on complicated wafer bonding, layer fracturing, and mechanical polishing steps. Rather, the methods allow the resonator and its components to be formed from a single crystal.

  7. Azeotropic binary solvent mixtures for preparation of organic single crystals

    NARCIS (Netherlands)

    Li, X.; Kjellander, B.K.C.; Anthony, J.E.; Bastiaansen, C.W.M.; Broer, D.J.; Gelinck, G.H.

    2009-01-01

    Here, a new approach is introduced to prepare large single crystals of π-conjugated organic molecules from solution. Utilizing the concept of azeotropism, single crystals of tri-isopropylsilylethynyl pentacene (TIPS-PEN) with dimensions up to millimeters are facilely self-assembled from homogeneous

  8. Growth of centimeter-sized C60 single crystals

    Institute of Scientific and Technical Information of China (English)

    李宏年; 徐亚伯; 张建华; 何丕模; 李海洋; 吴太权; 鲍世宁

    2001-01-01

    C60 single crystals larger than one centimeter in size are grown with vapor method by nucleation control and by a proper time-dependent temperature process which allows only one nucleus growing larger and larger. X-ray diffraction patterns exhibit the high quality of the sample. As an example of the applications of large single C60 crystals,svnchrotron radiation photoemission spectra are measured to investigate the fine structure of valence bands of C60 crystals.

  9. Investigation on Growth and Optical Properties of LVCC Single Crystals

    Directory of Open Access Journals (Sweden)

    N. Sheen Kumar

    2014-11-01

    Full Text Available L-valine cadmium chloride (LVCC single crystals were grown by slow evaporation technique with different concentrations (0.25, 0.5, 0.75 and 1.0 mole of CdCl2. All the grown crystals were subjected to single crystal X-ray diffraction analysis. Solid state parameters were calculated for the grown crystals. The optical properties of the crystals were investigated by UV-Vis. absorption spectroscopy. The results revealed that, the wider bandgap and large transparency in the visible region along with higher polarizability of the grown crystals are highly useful in optoelectronic devices. Also according to our needs, one can tune the optical and electrical properties of LVCC crystals by adjusting the concentration of CdCl2 in LVCC.

  10. Single crystal to single crystal transformation and hydrogen-atom transfer upon oxidation of a cerium coordination compound.

    Science.gov (United States)

    Williams, Ursula J; Mahoney, Brian D; Lewis, Andrew J; DeGregorio, Patrick T; Carroll, Patrick J; Schelter, Eric J

    2013-04-15

    Trivalent and tetravalent cerium compounds of the octamethyltetraazaannulene (H2omtaa) ligand have been synthesized. Electrochemical analysis shows a strong thermodynamic preference for the formal cerium(IV) oxidation state. Oxidation of the cerium(III) congener Ce(Homtaa)(omtaa) occurs by hydrogen-atom transfer that includes a single crystal to single crystal transformation upon exposure to an ambient atmosphere.

  11. Excitonic polaritons of zinc diarsenide single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Syrbu, N.N., E-mail: sirbunn@yahoo.com [Technical University of Moldova, Chisinau, Republic of Moldova (Moldova, Republic of); Stamov, I.G. [T.G. Shevchenko State University of Pridnestrovie, Tiraspol, Republic of Moldova (Moldova, Republic of); Zalamai, V.V. [Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau, Republic of Moldova (Moldova, Republic of); Dorogan, A. [Technical University of Moldova, Chisinau, Republic of Moldova (Moldova, Republic of)

    2017-02-01

    Excitonic polaritons of ZnAs{sub 2} single crystals had been investigated. Parameters of singlet excitons with Г{sub 2}¯(z) symmetry and orthoexcitons 2Г{sub 1}¯(y)+Г{sub 2}¯(x) had been determined. Spectral dependencies of ordinary and extraordinary dispersion of refractive index had been calculated using interferential reflection and transmittance spectra. It was shown, that A excitonic series were due to hole (V{sub 1}) and electron (C{sub 1}) bands. The values of effective masses of electrons (m{sub c}{sup *}=0.10 m{sub 0}) and holes (m{sub v1}{sup *}=0.89 m{sub 0}) had been estimated. It was revealed that the hole mass m{sub v1}{sup *} changes from 1.03 m{sub 0} to 0.55 m{sub 0} at temperature increasing from 10 K up to 230 K and that the electron mass m{sub c}{sup *} does not depend on temperature. The integral absorption A (eV cm{sup −1}) of the states n=1, 2 and 3 of Г{sub 2}¯(z) excitons depends on the A{sub n}≈n{sup −3} equality, which it is characteristic for S-type excitonic functions. Temperature dependences of the integral absorption of ground states for Г{sub 2}¯(z) and Г{sub 2}¯(Ñ…) excitons differ. The ground states of B and C excitons formed by V{sub 3} – C{sub 1} and V{sub 4} – C{sub 1} bands and its parameters had been determined.

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

    Science.gov (United States)

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

    2015-07-01

    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. 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.

  14. Simulation of Single Crystal Growth: Heat and Mass Transfer

    CERN Document Server

    Zhmakin, A I

    2015-01-01

    The heat transfer (conductive, convective, radiative) and the related problems (the unknown phase boundary fluid/crystal, the assessment of the quality of the grown crystals) encountered in the melt and vapour growth of single crystal as well as the corresponding macroscopic models are reviewed. The importance of the adequate description of the optical crystal properties (semitransparency, absorption, scattering, refraction, diffuse and specular reflecting surfaces) and their effect on the heat transfer is stressed. The problems of the code verification and validation are discussed; differences between the crystal growth simulation codes intended for the research and for the industrial applications are indicated.

  15. On the growth of calcium tartrate tetrahydrate single crystals

    Indian Academy of Sciences (India)

    X Sahaya Shajan; C Mahadevan

    2004-08-01

    Calcium tartrate single crystals were grown using silica gel as the growth medium. Calcium formate mixed with formic acid was taken as the supernatant solution. It was observed that the nucleation density was reduced and the size of the crystals was improved to a large extent compared to the conventional way of growing calcium tartrate crystals with calcium chloride. The role played by formate–formic acid on the growth of crystals is discussed. The grown crystals were characterized by atomic absorption spectroscopy (AAS), X-ray diffraction analysis (XRD), microhardness measurement, Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and differential thermal analysis (DTA). The results obtained are compared with the previous work.

  16. Physicochemical principles of high-temperature crystallization and single crystal growth methods

    Science.gov (United States)

    Bagdasarov, Kh. S.

    The mechanisms of crystal growth are reviewed, with attention given to the physicochemical reactions taking place in the melt near the phase boundary; phenomena determining physical and chemical kinetics directly at the growth front; solid-phase processes occurring within the crystal. Methods for growing refractory single crystals are discussed with particular reference to the Verneuil method, zone melting, Czhochralskii growth, horizontal directional solidification, and the Stockbarger method. Methods for growing crystals of complex geometrical shapes are also discussed.

  17. The Growth of Large Single Crystals.

    Science.gov (United States)

    Baer, Carl D.

    1990-01-01

    Presented is an experiment which demonstrates principles of experimental design, solubility, and crystal growth and structure. Materials, procedures and results are discussed. Suggestions for adapting this activity to the high school laboratory are provided. (CW)

  18. Growing Single Crystals of Compound Semiconductors

    Science.gov (United States)

    Naumann, Robert J.; Lehoczky, Sandor L.; Frazier, Donald O.

    1987-01-01

    Defect reduced by preventing melt/furnace contact and suppressing convention. Large crystals of compound semiconductors with few defects grown by proposed new method. Such materials as gallium arsenide and cadmium telluride produced, with quality suitable for very-large-scale integrated circuits or for large focal-plane arrays of photodetectors. Method used on small scale in Earth gravity, but needs microgravity to provide crystals large enough for industrial use.

  19. The optical properties of bismuth germanium oxide single crystals

    Directory of Open Access Journals (Sweden)

    ANDREJA VALCIC

    2000-09-01

    Full Text Available Bi12GeO20 single crystals were grown by the Czochralski technique. Suitable polishing and etching solutions were determined. Reflection spectra were recorded in the wave numbers range 20–5000 cm–1, and compared with the spectra of Bi12SiO20 single crystals to study the position of the phonon modes. The optical constants of the Bi12GeO20 single crystals were obtained using Kramers-Kronig analysis. The obtained results are dicussed and compared with published data.

  20. Dielectric and baric characteristics of TlS single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Mustafaeva, S.N., E-mail: solmust@gmail.com [Institute of Physics, ANAS, G. Javid prosp. 33, Az 1143 Baku (Azerbaijan); Asadov, M.M. [Institute of Chemical Problems, ANAS, G. Javid prosp. 29, Az 1143 Baku (Azerbaijan); Ismailov, A.A. [Institute of Physics, ANAS, G. Javid prosp. 33, Az 1143 Baku (Azerbaijan)

    2014-11-15

    The investigation of the frequency dependences of the dielectric coefficients and ac-conductivity of the TlS single crystals made it possible to elucidate the nature of dielectric loss and the charge transfer mechanism. Moreover, we evaluated the density and energy spread of localized states near the Fermi level, the average hopping time and the average hopping length. It was shown that the dc-conductivity of the TlS single crystals can be controlled by varying the hydrostatic pressure. This has opened up possibilities for using TlS single crystals as active elements of pressure detectors.

  1. Photon Cascade from a Single Crystal Phase Nanowire Quantum Dot

    DEFF Research Database (Denmark)

    Bouwes Bavinck, Maaike; Jöns, Klaus D; Zieliński, Michal

    2016-01-01

    unprecedented potential to be controlled with atomic layer accuracy without random alloying. We show for the first time that crystal phase quantum dots are a source of pure single-photons and cascaded photon-pairs from type II transitions with excellent optical properties in terms of intensity and line width...... quantum optical properties for single photon application and quantum optics.......We report the first comprehensive experimental and theoretical study of the optical properties of single crystal phase quantum dots in InP nanowires. Crystal phase quantum dots are defined by a transition in the crystallographic lattice between zinc blende and wurtzite segments and therefore offer...

  2. Growth and characterization of diammonium copper disulphate hexahydrate single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Siva Sankari, R. [Department of Physics, Agni College of Technology, Thalambur, Chennai 603103 (India); Perumal, Rajesh Narayana, E-mail: r.shankarisai@gmail.com [Department of Physics, SSN College of Engineering, Kalavakkam, Chennai 603110 (India)

    2014-03-01

    Graphical abstract: Diammonium copper disulphate hexahydrate (DACS) is one of the most promising inorganic dielectric crystals with exceptional mechanical properties. Good quality crystals of DACS were grown by using solution method in a period of 30 days. The grown crystals were subjected to single crystal X-ray diffraction analysis in order to establish their crystalline nature. Thermo gravimetric, differential thermal analysis, FTIR, and UV–vis–NIR analysis were performed for the crystal. Several solid state physical parameters have been determined for the grown crystals. The dielectric constant and the dielectric loss and AC conductivity of the grown crystal were studied as a function of frequency and temperature has been calculated and plotted. - Highlights: • Diammonium copper disulphate is grown for the first time and CCDC number obtained. • Thermal analysis is done to see the stability range of the crystals. • Band gap and UV cut off wavelength of the crystal are determined to be 2.4 eV and 472.86 nm, respectively. • Dielectric constant, dielectric loss and AC conductivity are plotted as a function of applied field. - Abstract: Diammonium copper disulphate hexahydrate is one of the most promising inorganic crystals with exceptional dielectric properties. A good quality crystal was harvested in a 30-day period using solution growth method. The grown crystal was subjected to various characterization techniques like single crystal X-ray diffraction analysis, thermo gravimetric, differential thermal analysis, FTIR, and UV–vis–NIR analysis. Unit cell dimensions of the grown crystal have been identified from XRD studies. Functional groups of the title compounds have been identified from FTIR studies. Thermal stability of the samples was checked by TG/DTA studies. Band gap of the crystal was calculated. The dielectric constant and dielectric loss were studied as a function of frequency of the applied field. AC conductivity was plotted as a function

  3. Growth and characterization of organic material 4-dimethylaminobenzaldehyde single crystal

    Science.gov (United States)

    Jebin, R. P.; Suthan, T.; Rajesh, N. P.; Vinitha, G.; Madhusoodhanan, U.

    2015-01-01

    The organic material 4-dimethylaminobenzaldehyde single crystals were grown by slow evaporation technique. The grown crystal was confirmed by the single crystal and powder X-ray diffraction analyses. The functional groups of the crystal have been identified from the Fourier Transform Infrared (FTIR) and FT-Raman studies. The optical property of the grown crystal was analyzed by UV-Vis-NIR and photoluminescence (PL) spectral measurements. The thermal behavior of the grown crystal was analyzed by thermogravimetric (TG) and differential thermal analyses (DTA). Dielectric measurements were carried out with different frequencies by using parallel plate capacitor method. The third order nonlinear optical properties of 4-dimethylaminobenzaldehyde was measured by the Z-scan technique using 532 nm diode pumped continuous wave (CW) Nd:YAG laser.

  4. Single crystal Processing and magnetic properties of gadolinium nickel

    Energy Technology Data Exchange (ETDEWEB)

    Shreve, Andrew John [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    GdNi is a rare earth intermetallic material that exhibits very interesting magnetic properties. Spontaneous magnetostriction occurs in GdNi at T{sub C}, on the order of 8000ppm strain along the c-axis and only until very recently the mechanism causing this giant magnetostriction was not understood. In order to learn more about the electronic and magnetic structure of GdNi, single crystals are required for anisotropic magnetic property measurements. Single crystal processing is quite challenging for GdNi though since the rare-earth transition-metal composition yields a very reactive intermetallic compound. Many crystal growth methods are pursued in this study including crucible free methods, precipitation growths, and specially developed Bridgman crucibles. A plasma-sprayed Gd2O3 W-backed Bridgman crucible was found to be the best means of GdNi single crystal processing. With a source of high-quality single crystals, many magnetization measurements were collected to reveal the magnetic structure of GdNi. Heat capacity and the magnetocaloric effect are also measured on a single crystal sample. The result is a thorough report on high quality single crystal processing and the magnetic properties of GdNi.

  5. Single-Crystal Bismuth Iodide Gamma-Ray Spectrometers

    Science.gov (United States)

    2012-02-01

    grow high quality Bib single crystals (> 1 cm3 in volume) via a high temperature modified Bridgman crystal growth technique. We will then test and...methods to improve Bib crystals. Finally, test structures will be designed and their performance will be assessed using a variety of small, calibrated...characteristics of the test structures (basic material properties for Bib ). While the main objectives of the project have not changed, more emphasis is

  6. Single crystals of V Amylose complexed with glycerol

    NARCIS (Netherlands)

    Hulleman, S.H.D.; Helbert, W.; Chanzy, H.

    1996-01-01

    Lamellar single crystals of amylose V glycerol were grown at 100°C by evaporating water from solutions of amylose in aqueous glycerol. The crystals which were square, with lateral dimensions of several micrometers, gave sharp electron diffraction patterns presenting an orthorhombic symmetry with a p

  7. Growth features of ammonium hydrogen -tartrate single crystals

    Indian Academy of Sciences (India)

    G Sajeevkumar; R Raveendran; B S Remadevi; Alexander Varghese Vaidyan

    2004-08-01

    Ammonium hydrogen -tartrate (-AHT) single crystals were grown in silica gel. The growth features of these crystals with variation of parameters like specific gravity of the gel, gel pH, acid concentrations, concentration of the feed solution and gel age were studied in detail.

  8. Ellipsometric studies of ErMnO3 single crystals

    DEFF Research Database (Denmark)

    Babonas, G.-J.; Grivel, Jean-Claude; Reza, A.

    2007-01-01

    Ellipsometric studies of ErMnO3 single crystals have been carried out in the spectral range of 1-5 eV by means of photometric ellipsometers. Experimental ellipsometric data were analysed in the uniaxial crystal model. For the first time, the components of dielectric function of ErMnO3 were...

  9. Ellipsometric studies of ErMnO3 single crystals

    DEFF Research Database (Denmark)

    Babonas, G.-J.; Grivel, Jean-Claude; Reza, A.;

    2007-01-01

    Ellipsometric studies of ErMnO3 single crystals have been carried out in the spectral range of 1-5 eV by means of photometric ellipsometers. Experimental ellipsometric data were analysed in the uniaxial crystal model. For the first time, the components of dielectric function of ErMnO3 were...

  10. Synthesis, Growth, and Characterization of Bisglycine Hydrobromide Single Crystal

    Directory of Open Access Journals (Sweden)

    Koteeswari Pandurangan

    2014-01-01

    Full Text Available Single crystals of BGHB were grown by slow evaporation technique. The unit cell dimensions and space group of the grown crystals were confirmed by single crystal X-ray diffraction. The modes of vibration of the molecules and the presence of functional groups were identified using FTIR technique. The microhardness study shows that the Vickers hardness number of the crystal increases with the increase in applied load. The optical properties of the crystals were determined using UV-Visible spectroscopy. The thermal properties of the grown crystal were also determined. The refractive index was determined as 1.396 using Brewster’s angle method. The emission of green light on passing the Nd: YAG laser light confirmed the second harmonic generation property of the crystals and the SHG efficiency of the crystals was found to be higher than that of KDP. The dielectric constant and dielectric loss measurements were carried out for different temperatures and frequencies. The ac conductivity study of the crystals was also discussed. The photoconductivity studies confirm that the grown crystal has negative photoconductivity nature. The etching studies were carried out to study the formation of etch pits.

  11. Dielectric behaviour of strontium tartrate single crystals

    Indian Academy of Sciences (India)

    S K Arora; Vipul Patel; Brijesh Amin; Anjana Kothari

    2004-04-01

    Strontium tartrate trihydrate (STT) crystals have been grown in silica hydrogel. Various polarization mechanisms such as atomic polarization of lattice, orientational polarization of dipoles and space charge polarization in the grown crystals have been understood using results of the measurements of dielectric constant (') and dielectric loss (tan ) as functions of frequency and temperature. Ion core type polarization is seen in the temperature range 75–180°C, and above 180°C, there is interfacial polarization for relatively lower frequency range. One observes dielectric dispersion at lower frequency presumably due to domain wall relaxation.

  12. Process for Forming a High Temperature Single Crystal Canted Spring

    Science.gov (United States)

    DeMange, Jeffrey J (Inventor); Ritzert, Frank J (Inventor); Nathal, Michael V (Inventor); Dunlap, Patrick H (Inventor); Steinetz, Bruce M (Inventor)

    2017-01-01

    A process for forming a high temperature single crystal canted spring is provided. In one embodiment, the process includes fabricating configurations of a rapid prototype spring to fabricate a sacrificial mold pattern to create a ceramic mold and casting a canted coiled spring to form at least one canted coil spring configuration based on the ceramic mold. The high temperature single crystal canted spring is formed from a nickel-based alloy containing rhenium using the at least one coil spring configuration.

  13. HEiDi: Single crystal diffractometer at hot source

    Directory of Open Access Journals (Sweden)

    Martin Meven

    2015-08-01

    Full Text Available The single crystal diffractometer HEiDi, which is operated by the Institute of Crystallography, RWTH Aachen University and JCNS, Forschungszentrum Jülich, is designed for detailed studies on structural and magnetic properties of single crystals using unpolarised neutrons and Bragg’s Law: 2dhklsinθ = λ (typically 0.55 Å <λ< 1.2 Å.

  14. Blocks and residual stresses in shaped sapphire single crystals

    Science.gov (United States)

    Krymov, V. M.; Nosov, Yu. G.; Bakholdin, S. I.; Maslov, V. N.; Shul‧pina, I. L.; Nikolaev, V. I.

    2017-01-01

    The formation of blocks and residual stresses in shaped sapphire crystals grown from the melt by the Stepanov method (EFG) has been studied. The probability of block formation is higher for the growth along the c axis compared to that grown in the a-axis direction. The distribution of residual stress in sapphire crystals of tubular, rectangular and round cross section was measured by the conoscopy method. It was found that the magnitude of the residual stress increases from the center to the periphery of the crystal and reaches up to about 20 MPa. Residual stress tensor components for solid round rod and tubular single crystals were determined by numerical integration.

  15. Growth and characterization of organic single crystal benzyl carbamate

    Science.gov (United States)

    Bala Solanki, S. Siva; Perumal, Rajesh Narayana; Suthan, T.; Bhagavannarayana, G.

    2015-10-01

    Benzyl carbamate single crystal is grown by a solution and vertical Bridgman technique for the first time. The cell parameters and morphologies are assessed from single crystal X-ray diffraction analysis. High resolution X-ray diffraction analysis indicates the crystalline perfection of the grown benzyl carbamate crystal. Fourier Transforms Infrared spectroscopy study has been applied to arrive at the different functional groups. Thermo gravimetric analysis and differential scanning calorimetry are used to study its thermal behavior. The microhardness test is carried out and the load dependent hardness is measured.

  16. Studies on crystal growth and physical properties of 2-amino-5-chloropyridine single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Suthan, T. [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam 603 110 (India); Rajesh, N.P., E-mail: rajeshnp@hotmail.com [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam 603 110 (India); Mahadevan, C.K. [Physics Research Centre, S.T. Hindu College, Nagercoil 629 002 (India); Bhagavannarayana, G. [C.G.C. Section, National Physical Laboratory, New Delhi 110 012 (India)

    2011-09-15

    Graphical abstract: 2-Amino-5-chloropyridine single crystal. Highlights: {yields} 2-Amino-5-chloropyridine single crystals grown by slow evaporation technique. {yields} Use acetone as solvent. {yields} Grown crystal conformed by XRD and FTIR. {yields} HRXRD, optical, thermal, dielectric and mechanical studies were analyzed. - Abstract: Organic 2-amino-5-chloropyridine single crystals have been grown by slow evaporation technique successfully. The grown crystal was confirmed by single and powder X-ray diffraction studies. The presence of functional groups was identified by Fourier transform infrared (FTIR) study. High resolution X-ray diffraction (HRXRD) analysis indicates the crystalline perfection of the grown crystal. UV-Vis-NIR analysis was performed to examine the optical property of the grown crystal. The thermal property of the grown crystal was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The dielectric measurements were carried out and the results indicate an increase in dielectric and conductivity parameters with the increase of temperature at all frequencies. The Vicker's hardness study reveals that the grown crystal is in soft nature.

  17. The lattice parameter of highly pure silicon single crystals

    Science.gov (United States)

    Becker, P.; Scyfried, P.; Siegert, H.

    1982-08-01

    From crystal to crystal comparison, the d 220 lattice spacing in PERFX and WASO silicon crystals used in the only two existing absolute measurements have been found to be equal within ±2×10-7 d 220. This demonstrates that generic variabilities of the two crystals account only for a small part of the 1.8×10-6 d 220 difference in the two absolute measurements. In a new series of 336 single measurements, our d 220 value reported recently has been confirmed within ±2×10-8 d 220. From these results we derive the following lattice parameter for highly pure silicon single crystals: a 0=(543 102.018±0.034) fm (at 22.5°C, in vacuum).

  18. The optical properties of alkali nitrate single crystals

    Science.gov (United States)

    Anan'ev, Vladimir; Miklin, Mikhail

    2000-08-01

    Absorption of non-polarized light by a uniaxial crystal has been studied. The degree of absorption polarization has been calculated as a function of the ratio of optical densities in the region of low and high absorbances. This function is proposed for analysis of the qualitative and quantitative characteristics of uniaxial crystal absorption spectra. Non-polarized light spectra of alkali nitrate single crystals, both pure and doped with thallium, have been studied. It is shown that the absorption band at 300 nm is due to two transitions, whose intensities depend on temperature in various ways. There is a weak band in a short wavelength range of the absorption spectrum of potassium nitrate crystal, whose intensity increases with thallium doping. The band parameters of alkali nitrate single crystals have been calculated. Low-energy transitions in the nitrate ion have been located.

  19. Growth and properties of benzil doped benzimidazole (BMZ) single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Babu, R. Ramesh, E-mail: rampap2k@yahoo.co.in [Crystal Growth and Thin Film Laboratory, School of Physics, Bharathidasan University, Tiruchirappalli 620 024 (India); Crystal Growth and Crystallography Section, National Physical Laboratory, Krishnan Marg, New Delhi 110 012 (India); Sukumar, M. [Crystal Growth and Thin Film Laboratory, School of Physics, Bharathidasan University, Tiruchirappalli 620 024 (India); Vasudevan, V. [Crystal Growth and Thin Film Laboratory, School of Physics, Bharathidasan University, Tiruchirappalli 620 024 (India); Crystal Growth and Crystallography Section, National Physical Laboratory, Krishnan Marg, New Delhi 110 012 (India); Shakir, Mohd. [Crystal Growth and Crystallography Section, National Physical Laboratory, Krishnan Marg, New Delhi 110 012 (India); Ramamurthi, K. [Crystal Growth and Thin Film Laboratory, School of Physics, Bharathidasan University, Tiruchirappalli 620 024 (India); Bhagavannarayana, G. [Crystal Growth and Crystallography Section, National Physical Laboratory, Krishnan Marg, New Delhi 110 012 (India)

    2010-09-15

    In the present work, we have made an attempt to study the effect of benzil doping on the properties of benzimidazole single crystals. For this purpose we have grown pure and benzil doped benzimidazole single crystals by vertical Bridgman technique. The grown crystals were characterized by various characterization techniques. The presence of dopants confirmed by powder X-ray diffraction (XRD). Crystalline perfection of the grown crystals has been analysed by high-resolution X-ray diffraction (HRXRD). The transmittance, electrical property and mechanical strength have been analysed using UV-vis-NIR spectroscopic, dielectric and Vicker's hardness studies. The relative second harmonic generation efficiency of pure and doped benzimidazole crystals measured using Kurtz powder test.

  20. Anisotropic behaviour of semiconducting tin monosulphoselenide single crystals

    Indian Academy of Sciences (India)

    T H Patel; Rajiv Vaidya; S G Patel

    2003-10-01

    Single crystals of ternary mixed compounds of group IV–VI in the form of a series, SnSSe1- (where = 0, 0.25, 0.50, 0.75 and 1), have been grown using direct vapour transport technique. The grown crystals were characterized by the X-ray diffraction analysis for their structural parameter determination. All the grown crystals were found to be orthorhombic. The microstructure analysis of the grown crystals reveals their layered type growth mechanism. From the Hall effect measurements Hall mobility, Hall coefficient and carrier concentration were calculated with all crystals showing -type nature. The d.c. electrical resistivity measurements perpendicular to -axis (i.e. along the basal plane) in the temperature range 303–453 K were carried out for grown crystals using four-probe method. The d.c. electrical resistivity measurements parallel to -axis (i.e. perpendicular to basal plane) in the temperature range 303–453 K were carried out for the same crystals. The electrical resistivity measurements showed an anisotropic behaviour of electrical resistivity for the grown crystals. The anisotropic behaviour and the effect of change in stoichiometric proportion of S and Se content on the electrical properties of single crystals of the series, SnSSe1- (where = 0, 0.25, 0.50, 0.75 and 1), is presented systematically.

  1. An analytical model for porous single crystals with ellipsoidal voids

    Science.gov (United States)

    Mbiakop, A.; Constantinescu, A.; Danas, K.

    2015-11-01

    A rate-(in)dependent constitutive model for porous single crystals with arbitrary crystal anisotropy (e.g., FCC, BCC, HCP, etc.) containing general ellipsoidal voids is developed. The proposed model, denoted as modified variational model (MVAR), is based on the nonlinear variational homogenization method, which makes use of a linear comparison porous material to estimate the response of the nonlinear porous single crystal. Periodic multi-void finite element simulations are used in order to validate the MVAR for a large number of parameters including cubic (FCC, BCC) and hexagonal (HCP) crystal anisotropy, various creep exponents (i.e., nonlinearity), several stress triaxiality ratios, general void shapes and orientations and various porosity levels. The MVAR model, which involves a priori no calibration parameters, is found to be in good agreement with the finite element results for all cases considered in the rate-dependent context. The model is then used in a predictive manner to investigate the complex response of porous single crystals in several cases with strong coupling between the anisotropy of the crystal and the (morphological) anisotropy induced by the shape and orientation of the voids. Finally, a simple way of calibrating the MVAR with just two adjustable parameters is depicted in the rate-independent context so that an excellent agreement with the FE simulation results is obtained. In this last case, this proposed model can be thought as a generalization of the Gurson model in the context of porous single crystals and general ellipsoidal void shapes and orientations.

  2. Anisotropy of nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Maier, R. D.; Dreshfield, R. L.

    1980-01-01

    The effects of crystal orientation on the mechanical properties of single crystals of the nickel-based superalloy Mar-M247 are investigated. Tensile tests at temperatures from 23 to 1093 C and stress rupture tests at temperatures from 760 to 1038 C were performed for 52 single crystals at various orientations. During tensile testing between 23 and 760 C, single crystals with high Schmid factors were found to be favorably oriented for slip and to exhibit lower strength and higher ductility than those with low Schmid factors. Crystals which required large rotations to become oriented for cross slip were observed to have the shortest stress rupture lives at 760 C, while those which required little or no rotation had the longest lives. In addition, stereographic triangles obtained for Mar-M247 and Mar-M200 single crystals reveal that crystals with orientations near the -111 had the highest lives, those near the 001 had high lives, and those near the 011 had low lives.

  3. Anisotropy of nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Maier, R. D.; Dreshfield, R. L.

    1980-01-01

    The effects of crystal orientation on the mechanical properties of single crystals of the nickel-based superalloy Mar-M247 are investigated. Tensile tests at temperatures from 23 to 1093 C and stress rupture tests at temperatures from 760 to 1038 C were performed for 52 single crystals at various orientations. During tensile testing between 23 and 760 C, single crystals with high Schmid factors were found to be favorably oriented for slip and to exhibit lower strength and higher ductility than those with low Schmid factors. Crystals which required large rotations to become oriented for cross slip were observed to have the shortest stress rupture lives at 760 C, while those which required little or no rotation had the longest lives. In addition, stereographic triangles obtained for Mar-M247 and Mar-M200 single crystals reveal that crystals with orientations near the -111 had the highest lives, those near the 001 had high lives, and those near the 011 had low lives.

  4. Cladded single crystal fibers for high power fiber lasers

    Science.gov (United States)

    Kim, W.; Shaw, B.; Bayya, S.; Askins, C.; Peele, J.; Rhonehouse, D.; Meyers, J.; Thapa, R.; Gibson, D.; Sanghera, J.

    2016-09-01

    We report on the recent progress in the development of cladded single crystal fibers for high power single frequency lasers. Various rare earth doped single crystal YAG fibers with diameters down to 17 μm with length > 1 m have been successfully drawn using a state-of-the-art Laser Heated Pedestal Growth system. Single and double cladding on rare earth doped YAG fibers have been developed using glasses where optical and physical properties were precisely matched to doped YAG core single crystal fiber. The double clad Yb:YAG fiber structures have dimensions analogous to large mode area (LMA) silica fiber. We also report successful fabrications of all crystalline core/clad fibers where thermal and optical properties are superior over glass cladded YAG fibers. Various fabrication methods, optical characterization and gain measurements on these cladded YAG fibers are reported.

  5. High-quality single crystals for neutron experiments

    Indian Academy of Sciences (India)

    Geetha Balakrishnan

    2008-10-01

    To make headway on any problem in physics, high-quality single crystals are required. In this talk, special emphasis will be placed on the crystal growth of various oxides (superconductors and magnetic materials), borides and carbides using the image furnaces at Warwick. The floating zone method of crystal growth used in these furnaces produces crystals of superior quality, circumventing many of the problems associated with, for example, flux growth from the melt. This method enables the growth of large volumes of crystal, a prerequisite especially for experiments using neutron beams. Some examples of experimental results from crystals grown at Warwick, selected from numerous in-house studies and our collaborative research projects with other UK and international groups will be discussed.

  6. Mesoporous zeolite single crystals for catalytic hydrocarbon conversion

    DEFF Research Database (Denmark)

    Schmidt, I.; Christensen, C.H.; Hasselriis, Peter

    2005-01-01

    transport to and from active sites and at the same time maintain the shape-selectivity required. Thus, all these results support the idea that the beneficial effect of the mesopores system in the mesoporous zeolite single crystals call be solely attributed to enhanced mass transport.......Recently, mesoporous zeolite single crystals were discovered. They constitute a novel family of materials that features a combined micropore and mesopore architecture within each individual crystal. Here, we briefly summarize recent catalytic results from cracking and isomerization of alkalies......, alkylation of aromatics and present new results on isomerization of aromatics. Specifically, the shape-selective isomerization of meta-xylenc into para-xylene and ortho-xylene is studied. In all these reactions, rnesoporous zeolite single crystals prove to be unique catalysts since they provide easy...

  7. Mesoporous zeolite single crystals for catalytic hydrocarbon conversion

    DEFF Research Database (Denmark)

    Schmidt, I.; Christensen, C.H.; Hasselriis, Peter

    2005-01-01

    Recently, mesoporous zeolite single crystals were discovered. They constitute a novel family of materials that features a combined micropore and mesopore architecture within each individual crystal. Here, we briefly summarize recent catalytic results from cracking and isomerization of alkalies......, alkylation of aromatics and present new results on isomerization of aromatics. Specifically, the shape-selective isomerization of meta-xylenc into para-xylene and ortho-xylene is studied. In all these reactions, rnesoporous zeolite single crystals prove to be unique catalysts since they provide easy...... transport to and from active sites and at the same time maintain the shape-selectivity required. Thus, all these results support the idea that the beneficial effect of the mesopores system in the mesoporous zeolite single crystals call be solely attributed to enhanced mass transport....

  8. Chemical Bond Analysis of Single Crystal Growth of Magnesium Oxide

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Starting from the crystallographic structure of magnesium oxide (MgO), both the chemical bond model of solids and Pauling's third rule (polyhedral sharing rule) were employed to quantitatively analyze the chemical bonding structure of constituent atoms and single crystal growth. Our analytical results show that MgO single crystals prefer to grow along the direction and the growth rate of the {100} plane is the slowest one. Therefore, the results show that the {100} plane of MgO crystals can be the ultimate morphology face, which is in a good agreement with our previous experimental results. The study indicate that the structure analysis is an effective tool to control the single-crystal growth.

  9. Method of making macrocrystalline or single crystal semiconductor material

    Science.gov (United States)

    Shlichta, P. J. (Inventor); Holliday, R. J. (Inventor)

    1986-01-01

    A macrocrystalline or single crystal semiconductive material is formed from a primary substrate including a single crystal or several very large crystals of a relatively low melting material. This primary substrate is deposited on a base such as steel or ceramic, and it may be formed from such metals as zinc, cadmium, germanium, aluminum, tin, lead, copper, brass, magnesium silicide, or magnesium stannide. These materials generally have a melting point below about 1000 C and form on the base crystals the size of fingernails or greater. The primary substrate has an epitaxial relationship with a subsequently applied layer of material, and because of this epitaxial relationship, the material deposited on the primary substrate will have essentially the same crystal size as the crystals in the primary substrate. If required, successive layers are formed, each of a material which has an epitaxial relationship with the previously deposited layer, until a layer is formed which has an epitaxial relationship with the semiconductive material. This layer is referred to as the epitaxial substrate, and its crystals serve as sites for the growth of large crystals of semiconductive material. The primary substrate is passivated to remove or otherwise convert it into a stable or nonreactive state prior to deposition of the seconductive material.

  10. Inspection of Single Crystal Aerospace Components with Ultrasonic Arrays

    Science.gov (United States)

    Lane, C. J. L.; Dunhill, A.; Drinkwater, B. W.; Wilcox, P. D.

    2010-02-01

    Single crystal metal alloys are used extensively in the manufacture of jet engine components for their excellent mechanical properties at elevated temperatures. The increasing use of these materials and demand for longer operational life and improved reliability motivates the requirement to have capable NDE methods available. Ultrasonic arrays are well established at detecting sub-surface defects however these methods are not currently suitable to the inspection of single crystal components due to their high elastic anisotropy causing directional variation in ultrasonic waves. In this paper a model of wave propagation in anisotropic material is used to correct an ultrasonic imaging algorithm and is applied to single crystal test specimens. The orientation of the crystal in a specimen must be known for this corrected-algorithm; therefore a crystal orientation method is also presented that utilizes surface skimming longitudinal waves under a 2D array. The work detailed in this paper allows an ultrasonic 2D array to measure the orientation of a single crystal material and then perform accurate volumetric imaging to detect and size defects.

  11. Error compensation of thin plate-shape part with prebending method in face milling

    Science.gov (United States)

    Yi, Wei; Jiang, Zhaoliang; Shao, Weixian; Han, Xiangcheng; Liu, Wenping

    2015-01-01

    Low weight and good toughness thin plate parts are widely used in modern industry, but its flexibility seriously impacts the machinability. Plenty of studies focus on the influence of machine tool and cutting tool on the machining errors. However, few researches focus on compensating machining errors through the fixture. In order to improve the machining accuracy of thin plate-shape part in face milling, this paper presents a novel method for compensating the surface errors by prebending the workpiece during the milling process. First, a machining error prediction model using finite element method is formulated, which simplifies the contacts between the workpiece and fixture with spring constraints. Milling forces calculated by the micro-unit cutting force model are loaded on the error prediction model to predict the machining error. The error prediction results are substituted into the given formulas to obtain the prebending clamping forces and clamping positions. Consequently, the workpiece is prebent in terms of the calculated clamping forces and positions during the face milling operation to reduce the machining error. Finally, simulation and experimental tests are carried out to validate the correctness and efficiency of the proposed error compensation method. The experimental measured flatness results show that the flatness improves by approximately 30 percent through this error compensation method. The proposed method not only predicts the machining errors in face milling thin plate-shape parts but also reduces the machining errors by taking full advantage of the workpiece prebending caused by fixture, meanwhile, it provides a novel idea and theoretical basis for reducing milling errors and improving the milling accuracy.

  12. Error Compensation of Thin Plate-shape Part with Prebending Method in Face Milling

    Institute of Scientific and Technical Information of China (English)

    YI Wei; JIANG Zhaoliang; SHAO Weixian; HAN Xiangcheng; LIU Wenping

    2015-01-01

    Low weight and good toughness thin plate parts are widely used in modern industry, but its flexibility seriously impacts the machinability. Plenty of studies focus on the influence of machine tool and cutting tool on the machining errors. However, few researches focus on compensating machining errors through the fixture. In order to improve the machining accuracy of thin plate-shape part in face milling, this paper presents a novel method for compensating the surface errors by prebending the workpiece during the milling process. First, a machining error prediction model using finite element method is formulated, which simplifies the contacts between the workpiece and fixture with spring constraints. Milling forces calculated by the micro-unit cutting force model are loaded on the error prediction model to predict the machining error. The error prediction results are substituted into the given formulas to obtain the prebending clamping forces and clamping positions. Consequently, the workpiece is prebent in terms of the calculated clamping forces and positions during the face milling operation to reduce the machining error. Finally, simulation and experimental tests are carried out to validate the correctness and efficiency of the proposed error compensation method. The experimental measured flatness results show that the flatness improves by approximately 30 percent through this error compensation method. The proposed method not only predicts the machining errors in face milling thin plate-shape parts but also reduces the machining errors by taking full advantage of the workpiece prebending caused by fixture, meanwhile, it provides a novel idea and theoretical basis for reducing milling errors and improving the milling accuracy.

  13. Benzothiazolium Single Crystals: A New Class of Nonlinear Optical Crystals with Efficient THz Wave Generation.

    Science.gov (United States)

    Lee, Seung-Heon; Lu, Jian; Lee, Seung-Jun; Han, Jae-Hyun; Jeong, Chan-Uk; Lee, Seung-Chul; Li, Xian; Jazbinšek, Mojca; Yoon, Woojin; Yun, Hoseop; Kang, Bong Joo; Rotermund, Fabian; Nelson, Keith A; Kwon, O-Pil

    2017-08-01

    Highly efficient nonlinear optical organic crystals are very attractive for various photonic applications including terahertz (THz) wave generation. Up to now, only two classes of ionic crystals based on either pyridinium or quinolinium with extremely large macroscopic optical nonlinearity have been developed. This study reports on a new class of organic nonlinear optical crystals introducing electron-accepting benzothiazolium, which exhibit higher electron-withdrawing strength than pyridinium and quinolinium in benchmark crystals. The benzothiazolium crystals consisting of new acentric core HMB (2-(4-hydroxy-3-methoxystyryl)-3-methylbenzo[d]thiazol-3-ium) exhibit extremely large macroscopic optical nonlinearity with optimal molecular ordering for maximizing the diagonal second-order nonlinearity. HMB-based single crystals prepared by simple cleaving method satisfy all required crystal characteristics for intense THz wave generation such as large crystal size with parallel surfaces, moderate thickness and high optical quality with large optical transparency range (580-1620 nm). Optical rectification of 35 fs pulses at the technologically very important wavelength of 800 nm in 0.26 mm thick HMB crystal leads to one order of magnitude higher THz wave generation efficiency with remarkably broader bandwidth compared to standard inorganic 0.5 mm thick ZnTe crystal. Therefore, newly developed HMB crystals introducing benzothiazolium with extremely large macroscopic optical nonlinearity are very promising materials for intense broadband THz wave generation and other nonlinear optical applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Crystal-Orientation Dependent Evolution of Edge Dislocations from a Void in Single Crystal Gu

    Institute of Scientific and Technical Information of China (English)

    SONG Zhen-Fei; ZHU Wen-Jun; DENG Xiao-Liang; HE Hong-Liang

    2006-01-01

    @@ The micro-void growth by dislocation emission under tensile loading is explored with focus on the influence of crystal orientations. Based on the elastic theory, a dislocation emission criterion is formulated. It is predicted that the preferential location of dislocation nucleation and its threshold stress are dependent on the crystal orientation.Large-scale molecular dynamics (MD) simulations are also performed for single crystal copper to illustrate the dislocation evolution pattern associated with a nano-void growth. The results are in line with those given by the theoretical prediction. As revealed by MD simulations, the characteristics of void growth at micro-scale depend greatly on the crystal-orientation.

  15. Crystallization phase diagram, the growth of large single crystals of bovine {beta}-Lactoglobulin A

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, D; Ohnishi, Y; Tanaka, I; Niimura, N, E-mail: niimura@mx.ibaraki.ac.jp

    2010-11-01

    A crystallization phase diagram defining the meta-stable region of bovine {beta}-lactoglobulin A ({beta}-Lg) was firstly determined by a dialysis method. We have succeeded in growing a large single crystal of {beta}-Lg by selecting a crystal grown in this ''meta-stable region'' method described in the present paper. The quality of protein crystals was characterized quantitatively via rapid X-ray data collections, followed by the use of Wilson plots to analyze their resulting average B-factors.

  16. Crystallization phase diagram, the growth of large single crystals of bovine β-Lactoglobulin A

    Science.gov (United States)

    Yagi, D.; Ohnishi, Y.; Tanaka, I.; Niimura, N.

    2010-11-01

    A crystallization phase diagram defining the meta-stable region of bovine β-lactoglobulin A (β-Lg) was firstly determined by a dialysis method. We have succeeded in growing a large single crystal of β-Lg by selecting a crystal grown in this "meta-stable region" method described in the present paper. The quality of protein crystals was characterized quantitatively via rapid X-ray data collections, followed by the use of Wilson plots to analyze their resulting average B-factors.

  17. Growth and high pressure studies of zirconium sulphoselenide single crystals

    Indian Academy of Sciences (India)

    K R Patel; R D Vaidya; M S Dave; S G Patel

    2009-11-01

    Transition metal trichalcogenides are well suited for extreme pressure lubrication. These materials being semiconducting and of layered structure may undergo structural and electronic transition under pressure. In this paper authors reported the details about synthesis and characterization of zirconium sulphoselenide single crystals. The chemical vapour transport technique was used for the growth of zirconium sulphoselenide single crystals. The energy dispersive analysis by X-ray (EDAX) gave the confirmation about the stoichiometry of the as-grown crystals and other structural characterizations were accomplished by X-ray diffraction (XRD) study. The variation of electrical resistance was monitored in a Bridgman opposed anvil set-up up to 8 GPa pressure to identify the occurrence of any structural transition. These crystals do not possess any structural transitions upto the pressure limit examined.

  18. Geometric constraints on phase coexistence in vanadium dioxide single crystals

    Science.gov (United States)

    McGahan, Christina; Gamage, Sampath; Liang, Jiran; Cross, Brendan; Marvel, Robert E.; Haglund, Richard F.; Abate, Yohannes

    2017-02-01

    The appearance of stripe phases is a characteristic signature of strongly correlated quantum materials, and its origin in phase-changing materials has only recently been recognized as the result of the delicate balance between atomic and mesoscopic materials properties. A vanadium dioxide (VO2) single crystal is one such strongly correlated material with stripe phases. Infrared nano-imaging on low-aspect-ratio, single-crystal VO2 microbeams decorated with resonant plasmonic nanoantennas reveals a novel herringbone pattern of coexisting metallic and insulating domains intercepted and altered by ferroelastic domains, unlike previous reports on high-aspect-ratio VO2 crystals where the coexisting metal/insulator domains appear as alternating stripe phases perpendicular to the growth axis. The metallic domains nucleate below the crystal surface and grow towards the surface with increasing temperature as suggested by the near-field plasmonic response of the gold nanorod antennas.

  19. Single-Crystal Structure of a Covalent Organic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, YB; Su, J; Furukawa, H; Yun, YF; Gandara, F; Duong, A; Zou, XD; Yaghi, OM

    2013-11-06

    The crystal structure of a new covalent organic framework, termed COF-320, is determined by single-crystal 3D electron diffraction using the rotation electron diffraction (RED) method for data collection. The COF crystals are prepared by an imine condensation of tetra-(4-anilyl)methane and 4,4'-biphenyldialdehyde in 1,4-dioxane at 120 degrees C to produce a highly porous 9-fold interwoven diamond net. COF-320 exhibits permanent porosity with a Langmuir surface area of 2400 m(2)/g and a methane total uptake of 15.0 wt % (176 cm(3)/cm(3)) at 25 degrees C and 80 bar. The successful determination of the structure of COF-320 directly from single-crystal samples is an important advance in the development of COF chemistry.

  20. Geometric constraints on phase coexistence in vanadium dioxide single crystals.

    Science.gov (United States)

    McGahan, Christina; Gamage, Sampath; Liang, Jiran; Cross, Brendan; Marvel, Robert E; Haglund, Richard F; Abate, Yohannes

    2017-02-24

    The appearance of stripe phases is a characteristic signature of strongly correlated quantum materials, and its origin in phase-changing materials has only recently been recognized as the result of the delicate balance between atomic and mesoscopic materials properties. A vanadium dioxide (VO2) single crystal is one such strongly correlated material with stripe phases. Infrared nano-imaging on low-aspect-ratio, single-crystal VO2 microbeams decorated with resonant plasmonic nanoantennas reveals a novel herringbone pattern of coexisting metallic and insulating domains intercepted and altered by ferroelastic domains, unlike previous reports on high-aspect-ratio VO2 crystals where the coexisting metal/insulator domains appear as alternating stripe phases perpendicular to the growth axis. The metallic domains nucleate below the crystal surface and grow towards the surface with increasing temperature as suggested by the near-field plasmonic response of the gold nanorod antennas.

  1. Modelling of Heat Transfer in Single Crystal Growth

    CERN Document Server

    Zhmakin, Alexander I

    2014-01-01

    An attempt is made to review the heat transfer and the related problems encountered in the simulation of single crystal growth. The peculiarities of conductive, convective and radiative heat transfer in the different melt, solution, and vapour growth methods are discussed. The importance of the adequate description of the optical crystal properties (semitransparency, specular reflecting surfaces) and their effect on the heat transfer is stresses. Treatment of the unknown phase boundary fluid/crystal as well as problems related to the assessment of the quality of the grown crystals (composition, thermal stresses, point defects, disclocations etc.) and their coupling to the heat transfer/fluid flow problems is considered. Differences between the crystal growth simulation codes intended for the research and for the industrial applications are indicated. The problems of the code verification and validation are discussed; a brief review of the experimental techniques for the study of heat transfer and flow structu...

  2. Crystallization in Emulsions: A Thermo-Optical Method to Determine Single Crystallization Events in Droplet Clusters

    Directory of Open Access Journals (Sweden)

    Serghei Abramov

    2016-08-01

    Full Text Available Delivery systems with a solid dispersed phase can be produced in a melt emulsification process. For this, dispersed particles are melted, disrupted, and crystallized in a liquid continuous phase (melt emulsification. Different to bulk crystallization, droplets in oil-in-water emulsions show individual crystallization behavior, which differs from droplet to droplet. Therefore, emulsion droplets may form liquid, amorphous, and crystalline structures during the crystallization process. The resulting particle size, shape, and physical state influence the application properties of these colloidal systems and have to be known in formulation research. To characterize crystallization behavior of single droplets in micro emulsions (range 1 µm to several hundred µm, a direct thermo-optical method was developed. It allows simultaneous determination of size, size distribution, and morphology of single droplets within droplet clusters. As it is also possible to differentiate between liquid, amorphous, and crystalline structures, we introduce a crystallization index, CIi, in dispersions with a crystalline dispersed phase. Application of the thermo-optical approach on hexadecane-in-water model emulsion showed the ability of the method to detect single crystallization events of droplets within emulsion clusters, providing detailed information about crystallization processes in dispersions.

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

    OpenAIRE

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

    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. 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 e...

  4. Synthesis, crystal growth and mechanical properties of Bismuth Silicon Oxide (BSO) single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Riscob, B. [CSIR – National Physical Laboratory, Crystal Growth and X-ray Analysis, New Delhi 110 012 (India); Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat (India); Shkir, Mohd. [CSIR – National Physical Laboratory, Crystal Growth and X-ray Analysis, New Delhi 110 012 (India); Ganesh, V. [Department of Physics, Kakatiya University, Warangal 506 009 (India); Vijayan, N.; Maurya, K.K. [CSIR – National Physical Laboratory, Crystal Growth and X-ray Analysis, New Delhi 110 012 (India); Kishan Rao, K. [Department of Physics, Kakatiya University, Warangal 506 009 (India); Bhagavannarayana, G., E-mail: bhagavan@mail.nplindia.ernet.in [CSIR – National Physical Laboratory, Crystal Growth and X-ray Analysis, New Delhi 110 012 (India)

    2014-03-05

    Highlights: • Synthesis of Bismuth Silicon Oxide (BSO). • Single crystal growth of BSO by Czochralski (Cz) method. • Complete mechanical analysis by device fabrication point of view. • Theoretical and experimental calculations of mechanical properties. -- Abstract: Bismuth Silicon Oxide (BSO) is an efficient material for piezo-electric and electro-optic applications. In this article, growth of BSO single crystal by high temperature Czochralski melt growth technique and its detailed mechanical characterization by Vickers microhardness, fracture toughness, crack propagation, brittleness index and yield strength have been reported. The raw material was synthesized by solid state reaction using the stoichiometric ratio of high purity bismuth tri-oxide and silicon di-oxide. The synthesized material was charged in the platinum crucible and then melted. The required rotation and pulling rate was optimized for BSO single crystal growth and good quality single crystal has been harvested after a time span of 5 days. Powder X-ray diffraction analysis confirms the parent crystallization phase of BSO. The experimentally studied mechanical behavior of the crystal is explained using various theoretical models. The anisotropic nature of the crystals is studied using Knoop indentation technique.

  5. Skylab experiments on semiconductors and alkali halides. [single crystal growth

    Science.gov (United States)

    Lundquist, C. A.

    1974-01-01

    The space processing experiments performed during the Skylab missions included one on single crystal growth of germanium selenide and telluride, one on pure and doped germanium crystals, two on pure and doped indium antimonide, one on gallium-indium-antimony systems, and one on a sodium chloride-sodium fluoride eutectic. In each experiment, three ampoules of sample were processed in the multipurpose electric furnace within the Skylab Materials Processing Facility. All were successful in varying degrees and gave important information about crystal growth removed from the effects of earth surface gravity.

  6. Is the methanation reaction over Ru single crystals structure dependent?

    DEFF Research Database (Denmark)

    Vendelbo, Søren Bastholm; Johansson, Martin; Nielsen, Jane Hvolbæk;

    2011-01-01

    The influence of monoatomic steps and defects on the methanation reaction over ruthenium has been investigated. The experiments are performed on a Ru(0 1 54) ruthenium single crystal, which contains one monoatomic step atom for each 27 terrace atoms. The methanation activity is measured at one ba...... front-side of the crystal is poisoned faster than the entire crystal containing more defects. We also observe that additional sputtering of the well-defined front-side increases the reactivity measured on the surface. Based on this, we conclude that the methanation reaction takes place...

  7. Single Crystal Growth of Zirconia Utilizing a Skull Melting Technique,

    Science.gov (United States)

    1979-08-01

    help eliminate many crystal growth problems. The flame-fusion apparatus was invented by A. Verneuil 3 over 75 years ago and has been used for growth of...AOAO2 23 OMEAIRDEVLOPENT CNT RI RIFISS AFB NY F /S .7/ NGLE CRYSTAL GROWTH OF Z RONA UT IXZIN A SKULL MELTING TE-SCUl AUG 79 A C MARSHALL, J A ADAMSK...Crucible-less synthesis 50. ABSTRACT (Ceefiw.. - eooe edi. ,.e.eimwd identiby Slek ~b.,) Investigation into the growth of single crystal materials are

  8. 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.

  9. Heterogeneous Monolithic Integration of Single-Crystal Organic Materials.

    Science.gov (United States)

    Park, Kyung Sun; Baek, Jangmi; Park, Yoonkyung; Lee, Lynn; Hyon, Jinho; Koo Lee, Yong-Eun; Shrestha, Nabeen K; Kang, Youngjong; Sung, Myung Mo

    2017-02-01

    Manufacturing high-performance organic electronic circuits requires the effective heterogeneous integration of different nanoscale organic materials with uniform morphology and high crystallinity in a desired arrangement. In particular, the development of high-performance organic electronic and optoelectronic devices relies on high-quality single crystals that show optimal intrinsic charge-transport properties and electrical performance. Moreover, the heterogeneous integration of organic materials on a single substrate in a monolithic way is highly demanded for the production of fundamental organic electronic components as well as complex integrated circuits. Many of the various methods that have been designed to pattern multiple heterogeneous organic materials on a substrate and the heterogeneous integration of organic single crystals with their crystal growth are described here. Critical issues that have been encountered in the development of high-performance organic integrated electronics are also addressed.

  10. Surface enhanced raman spectroscopy studies on triglycine sulphate single crystals

    Science.gov (United States)

    Parameswari, A.; Mohamed Asath, R.; Premkumar, R.; Milton Franklin Benial, A.

    2017-01-01

    Adsorption characteristics of triglycine sulphate (TGS) on silver (Ag) surface were investigated based on density functional theory calculations and surface enhanced Raman spectroscopy (SERS) technique. The single crystals of TGS were grown by slow evaporation method. Ag nanoparticles (Ag NPs) were prepared by solution combustion method and characterized. The calculated and observed structural parameters of TGS molecule were compared. Raman and SERS spectra for TGS single crystal were studied experimentally and validated theoretically. Frontier molecular orbitals (FMOs) analysis was carried out for TGS and TGS adsorbed on Ag surface. The second harmonic generation measurements confirm the nonlinear optical (NLO) activity of the TGS molecule. SERS spectral analysis reveals that the TGS adsorbed as tilted orientation on the silver surface. The theoretical and experimental results evidence the suitability of the grown TGS single crystal for optoelectronic applications.

  11. Corelli: Efficient single crystal diffraction with elastic discrimination

    Indian Academy of Sciences (India)

    Stephan Rosenkranz; Raymond Osborn

    2008-10-01

    Single crystal diffuse scattering provides one of the most powerful probes of short-range correlations on the 1-100 nm scale, which often are responsible for the extreme field response of many emerging phenomena of great interest. Accurate modeling of such complex disorder from diffuse scattering data however puts stringent experimental demands, requiring measurements over large volumes of reciprocal space with sufficient momentum and energy resolution. Here, we discuss the potential of the cross-correlation technique for efficient measurement of single crystal diffuse scattering with energy discrimination, as will be implemented in a novel instrument, Corelli. Utilizing full experiment simulations, we show that this technique readily leads up to a fifty-fold gain in efficiency, as compared to traditional methods, for measuring single crystal diffuse scattering over volumes of reciprocal space with elastic discrimination.

  12. Single crystal surface structure by bragg scattering

    DEFF Research Database (Denmark)

    Nielsen, Mogens

    1985-01-01

    X-ray diffraction is becoming an important tool in the measurements of surface structures. Single crystalline samples are used as in Low Energy Electron Diffraction (LEED)-studies. The X-ray technique is somewhat more involved due to the need of bright, collimated photon sources, in general...... synchrotron X-rays, and of very accurate angular settings in the ultrahigh-vacuum environment of the sample. We present the technique and discuss examples of experimental results....

  13. Crystal growth and characterization of new semiorganic nonlinear optical single crystals

    Science.gov (United States)

    Kulshrestha, Shobha; Shrivastava, A. K.

    2016-05-01

    An organic material of a L-histidine monohydrochloride single crystal was grown in a distilled water solution using the slow evaporation method at 40-45°C. The grown crystal was transparent and colourless, with a size of about 20 × 9 × 5 mm3, obtained within a period of 21 days. The solubility of grown crystals have found out at various temperatures. The UV-visible transmittance studies show that the grown crystals have wide optical transparency in the entire visible region It is observed that the crystal has transparency window from 255nm to 700nm and its energy gap (Eg) found to be is 3.1eV. The grown crystal was subjected to powder X-ray diffraction analysis, confirming that the orthorhombic crystalline nature of the crystal. To identify the surface morphology, the as grown crystal was subjected to FE-SEM technique. The chemical composition of the grown crystal was estimated by Energy dispersive X-ray analysis. The optical behaviour of the grown crystal was analyzed by PL study.

  14. Modeling of elastic and plastic waves for HCP single crystals in a 3D formulation based on zinc single crystal

    Science.gov (United States)

    Krivosheina, Marina; Kobenko, Sergey; Tuch, Elena; Kozlova, Maria

    2016-11-01

    This paper investigates elastic and plastic waves in HCP single crystals through the numerical simulation of strain processes in anisotropic materials based on a zinc single crystal. Velocity profiles for compression waves in the back surfaces of single-crystal zinc plates with impact loading oriented in 0001 and 10 1 ¯0 are presented in this work as a part of results obtained in numerical simulations. The mathematical model implemented in this study reflects the following characteristics of the mechanical properties inherent in anisotropic (transtropic) materials: varying degree of anisotropy of elastic and plastic properties, which includes reverse anisotropy, dependence of distribution of all types of waves on the velocity orientation, and the anisotropy of compressibility. Another feature of elastic and plastic waves in HCP single crystals is that the shock wave does not split into an elastic precursor and "plastic" compression shock wave, which is inherent in zinc single crystals with loading oriented in 0001. The study compares numerical results obtained in a three-dimensional formulation with the results of velocity profiles from the back surfaces of target plates obtained in real experiments. These results demonstrate that the mathematical model is capable of describing the properties of the above-mentioned anisotropic (transtropic) materials.

  15. Aluminum-rich mesoporous MFI - type zeolite single crystals

    DEFF Research Database (Denmark)

    Kustova, Marina; Kustov, Arkadii; Christensen, Christina Hviid

    2005-01-01

    . With this technique, only zeolites with relatively low Al contents were reported (Si/Al ratio about 100). In this work, the preparation of aluminum-rich mesoporous MFI-type zeolite single crystals (Si/Al similar to 16-50) using aluminum isopropoxide as the aluminum Source is reported for the first time. All samples......Zeolitcs are crystalline materials, which are widely used as solid acid catalysts and supports in many industrial processes. Recently, mesoporous MFI-type zeolite single crystals were synthesized by use of carbon particles as a mesopore template and sodium aluminate as the aluminum Source...

  16. Apparatus And Method For Producing Single Crystal Metallic Objects

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shyh-Chin (Latham, NY); Gigliotti, Jr., Michael Francis X. (Scotia, NY); Rutkowski, Stephen Francis (Duanesburg, NY); Petterson, Roger John (Fultonville, NY); Svec, Paul Steven (Scotia, NY)

    2006-03-14

    A mold is provided for enabling casting of single crystal metallic articles including a part-defining cavity, a sorter passage positioned vertically beneath and in fluid communication with the part-defining cavity, and a seed cavity positioned vertically beneath and in fluid communication with the sorter passage. The sorter passage includes a shape suitable for encouraging a single crystal structure in solidifying molten metal. Additionally, a portion of the mold between the sorter passage and the part-defining cavity includes a notch for facilitating breakage of a cast article proximate the notch during thermal stress build-up, so as to prevent mold breakage or the inclusion of part defects.

  17. Growth of Solid Solution Single Crystals

    Science.gov (United States)

    Lehoczky, Sandor L.; Szofran, F. R.; Gillies, Donald C.

    2001-01-01

    The solidification of a solid solution semiconductor, having a wide separation between liquidus and solidus has been extensively studied in ground based, high magnetic field and Spacelab experiments. Two alloys of mercury cadmium telluride have been studied; with 80.0 mole percent of HgTe and 84.8 mole percent of HgTe respectively, the remainder being cadmium telluride. Such alloys are extremely difficult to grow by directional solidification on earth due to high solutal and thermal density differences that give rise to fluid flow and consequent loss of interface shape and composition. Diffusion controlled growth is therefore impossible to achieve in conventional directional solidification. The ground based experiments consisted of growing crystals in several different configurations of heat pipe furnaces, NASA's Advanced Automated Directional Solidification Furnace (AADSF), and a similar furnace incorporated in a superconducting magnet capable of operating at up to 5T. The first microgravity experiment took place during the flight of STS-62 in March 1994, with the AADSF installed on the second United States Microgravity Payload (USMP-2). The alloy was solidified at 3/4 inch per day over a 9 day period, and for the first time a detailed evaluation was performed correlating composition variations to measured residual acceleration. The second flight experiment took place in the fourth United States Microgravity Payload Mission (USMP-4) in November 1997. Due to contamination of the furnace system, analysis shows that the conditions prevailing during the experiment were quite different from the requirements requested prior to the mission. The results indicate that the sample did accomplish the desired objectives.

  18. Role of crystal orientation on chemical mechanical polishing of single crystal copper

    Science.gov (United States)

    Zhu, Aibin; He, Dayong; Luo, Wencheng; Liu, Yangyang

    2016-11-01

    The material removal mechanism of single crystal copper in chemical mechanical polishing (CMP) has not been intensively investigated. And the role of crystal orientation in CMP of single crystal cooper is not quite clear yet. Quasi-continuum method was adopted in this paper to simulate the process of nano-particles grinding on single crystal copper in CMP process. Three different crystal orientations, i.e. x[100]y[001], x[001]y[110] and x[-211]y[111], were chosen for analysis. The atom displacement diagrams, stress distribution diagrams and load-displacement curves were obtained. After analyzing the deformation mechanism, residual stress of the work piece material and cutting force, results showed that, the crystal orientation of work piece has great influence on the deformation characteristics and surface quality of work piece during polishing. In the A(001)[100] orientation, the residual stress distribution after polishing is deeper, and the stress is larger than that in the B(110)[001] and C(111)[-211] orientations. And the average tangential cutting force in the A(001)[100] orientation is much larger than those in the other two crystal orientation. This research is helpful to revealing the material removal mechanism of CMP process.

  19. Growth and characterization of morpholinium dihydrogenphosphate single crystal

    Science.gov (United States)

    Babu, D. Rajan; Arul, H.; Vizhi, R. Ezhil

    2016-10-01

    Morpholinium dihydrogenphosphate (MDP) single crystals were synthesized, and were subsequently grown by controlled evaporation technique at room temperature for nonlinear optical applications. The grown crystal, which belongs to the monoclinic system with the space group P21, was subjected to single crystal X-ray diffraction to confirm the structure. UV-vis-NIR spectroscopy was done on the grown crystal and it showed good optical transparency in the entire visible region with a minimum cut-off wavelength of 289 nm. The optical band gap was computed as a function of photon energy using Tauc's plot. The refractive index of the grown crystal was determined using a Metricon Prism Coupler. The thermogravimetric (TG) and differential thermal analysis (DTA) traces disclosed the thermal stability of the compound. The mechanical strength of the crystal was investigated by a Vickers microhardness tester. Dielectric constant and dielectric loss were calculated and plotted as a function of frequency at different temperatures. The second harmonic conversion efficiency was determined using the Kurtz-Perry powder technique, and the efficiency was found to be 1.2 times greater than that of standard KDP.

  20. Studies on growth, crystal structure and characterization of novel organic nicotinium trifluoroacetate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dhanaraj, P.V. [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam 603 110 (India); Rajesh, N.P., E-mail: rajeshnp@hotmail.com [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam 603 110 (India); Sundar, J. Kalyana; Natarajan, S. [Department of Physics, Madurai Kamaraj University, Madurai 625 021 (India); Vinitha, G. [Department of Physics, Crescent Engineering College, Chennai 600 048 (India)

    2011-09-15

    Highlights: {yields} Good quality crystals of nicotinium trifluoroacetate in monoclinic system were grown for first time. {yields} Nicotinium trifluoroacetate crystal exhibits third order nonlinear optical properties. {yields} The optical spectrum of nicotinium trifluoroacetate crystal reveals the wide transmission in the entire range with cutoff wavelength at 286 nm. {yields} Nicotinium trifluoroacetate is a low dielectric constant material. - Abstract: An organic material, nicotinium trifluoroacetate (NTF) was synthesized and single crystals in monoclinic system were grown from aqueous solution for the first time. Its solubility and metastable zone width were estimated. The crystal structure of NTF was analyzed to reveal the molecular arrangements and the formation of hydrogen bonds in the crystal. High-resolution X-ray diffraction rocking curve measurements were performed to analyze the structural perfection of the grown crystals. Functional groups in NTF were identified by Fourier transform infrared spectral analysis. Thermal behaviour and stability of NTF were studied by thermogravimetric and differential thermal analysis and differential scanning calorimetry. Mechanical and dielectric properties of NTF crystals were analyzed. Optical studies reveal that NTF crystals are transparent in the wavelength range 286-1100 nm. The third order nonlinear optical parameters of NTF were derived by the Z-scan technique.

  1. Decrease of bulk pinning strength in deoxygenated YBCO single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, A.J.; Bekeris, V. [Buenos Aires Univ. (Argentina). Lab. de Bajas Temperaturas

    2000-07-01

    We measured the first and third harmonics of the complex AC susceptibility in YBCO single crystals with different oxygen contents (6.5 {<=} x {<=} 7). The amplitude of the AC field was varied in presence of an external dc field both applied parallel to the c-axis of the crystals. We give evidence that deoxygenation leads to a reduction of the bulk pinning strength and consequently to a stronger contribution of geometrical barriers. These results support the recently reported investigations showing that deoxygenation makes the YBCO crystals more anisotropic reducing the effective bulk pinning for quasi two-dimensional vortices. We also show measurements for the same crystals with the AC field applied perpendicular to the c-axis. (orig.)

  2. Mg-ion indiffusion of lithium niobate single crystal fiber

    Institute of Scientific and Technical Information of China (English)

    阙文修; 姚熹; 霍玉晶

    1995-01-01

    A core-cladding waveguide structure of lithium niobate single crystal fiber with different refractive index profiles has been obtained by using an Mg-ion indiffusion process. The propagation loss of the dadded crystal fiber is measured to be 14 times as low as that of the undadded crystal fibers. Mechanisms of Mg-ion indiffusion and reasons of lattice distortion are analyzed and discussed. It is found by X-ray diffraction analysis as well as scanning electron microscopy that MgO-rich layer in the magnesium diffused surface exhibits the crystal structure of a new compound from the Li-Mg-Nb-O ternary system. It is proposed, for the first time, that this new compound in MgO-rich layer is the real source of Mg-ion indiffusion lithium niobate.

  3. Growth and characterisation of gadolinium samarium oxalate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Korah, I. [Dept. of Physics, St. George College, Aruvithura - 686122, Kerala (India); Joseph, C. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam - 686562 (India); Ittyachan, M.A. [Dept. of Physics, Cochin University of Science and Technology, Cochin (India)

    2007-10-15

    Single crystals of Gadolinium Samarium Oxalate (GSO) are grown by gel method. The crystals are pale yellowish in colour. Morphology and size of the crystals are found to depend on pH of the medium, gel density, concentration of the reactants and acidity of the feed solution. The crystallinity of the grown sample was confirmed by X-ray diffraction studies and the lattice parameters were determined. X-ray diffractogram shows well defined peaks. IR spectrum confirms the presence of water molecules and carboxylic group. EDAX analysis confirms the presence of Gd and Sm in the sample. The thermal decomposition behaviour of the crystal was analysed using TGA and DTA studies. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Note: High-power piezoelectric transformer fabricated with ternary relaxor ferroelectric Pb(Mg(1/3)Nb(2/3))O3-Pb(In(1/2)Nb(1/2))O3-PbTiO3 single crystal.

    Science.gov (United States)

    Wang, Qing; Ma, Chuanguo; Wang, Feifei; Liu, Bao; Chen, Jianwei; Luo, Haosu; Wang, Tao; Shi, Wangzhou

    2016-03-01

    A plate-shaped piezoelectric transformer was designed and fabricated using ternary relaxor ferroelectric single crystal Pb(Mg(1/3)Nb(2/3))O3-Pb(In(1/2)Nb(1/2))O3-PbTiO3. Both the input and output sections utilized the transverse-extensional vibration mode. The frequency and load dependences of the electrical properties for the proposed transformer were systematically studied. Results indicated that under a matching load resistance of 14.9 kΩ, a maximum output power of 2.56 W was obtained with the temperature rise less than 5 °C. The corresponding power density reached up to 50 W/cm(3). This ternary single-crystal transformer had potential applications in compact-size converters requiring high power density.

  5. Note: High-power piezoelectric transformer fabricated with ternary relaxor ferroelectric Pb(Mg1/3Nb2/3)O3-Pb(In1/2Nb1/2)O3-PbTiO3 single crystal

    Science.gov (United States)

    Wang, Qing; Ma, Chuanguo; Wang, Feifei; Liu, Bao; Chen, Jianwei; Luo, Haosu; Wang, Tao; Shi, Wangzhou

    2016-03-01

    A plate-shaped piezoelectric transformer was designed and fabricated using ternary relaxor ferroelectric single crystal Pb(Mg1/3Nb2/3)O3-Pb(In1/2Nb1/2)O3-PbTiO3. Both the input and output sections utilized the transverse-extensional vibration mode. The frequency and load dependences of the electrical properties for the proposed transformer were systematically studied. Results indicated that under a matching load resistance of 14.9 kΩ, a maximum output power of 2.56 W was obtained with the temperature rise less than 5 °C. The corresponding power density reached up to 50 W/cm3. This ternary single-crystal transformer had potential applications in compact-size converters requiring high power density.

  6. Compression Deformation Mechanisms at the Nanoscale in Magnesium Single Crystal

    Institute of Scientific and Technical Information of China (English)

    Yafang GUO; Xiaozhi TANG; Yuesheng WANG; Zhengdao WANG; Sidney YIP

    2013-01-01

    The dominant deformation mode at low temperatures for magnesium and its alloys is generally regarded to be twinning because of the hcp crystal structure.More recently,the phenomenon of a "loss" of the twins has been reported in microcompression experiments of the magnesium single crystals.Molecular dynamics simulation of compression deformation shows that the pyramidal slip dominates compression behavior at the nanoscale.No compression twins are observed at different temperatures at different loadings and boundary conditions.This is explained by the analyses,that is,the {10(1-)2} and {101-1} twins can be activated under c-axis tension,while compression twins will not occur when the c/a ratio of the hcp metal is below (/)3.Our theoretical and simulation results are consistent with recent microcompression experiments of the magnesium (0001) single crystals.

  7. Thermal properties of single-walled carbon nanotube crystal

    Institute of Scientific and Technical Information of China (English)

    Hu Li-Jun; Liu Ji; Liu Zheng; Qiu Cai-Yu; Zhou Hai-Qing; Sun Lian-Feng

    2011-01-01

    In this work,the thermal properties of a single-walled carbon nanotube (SWCNT) crystal are studied. The thermal conductivity of the SWCNT crystal is found to have a linear dependence on temperature in the temperature range from 1.9 K to 100.0 K. In addition,a peak (658 W/mK) is found at a temperature of about 100.0 K. The thermal conductivity decreases gradually to a value of 480 W/mK and keeps almost a constant in the temperature range from 100.0 K to 300.0 K. Meanwhile,the specific heat shows an obvious linear relationship with temperature in the temperature range from 1.9 K to 300.0 K. We discuss the possible mechanisms for these unique thermal properties of the single-walled carbon nanotube crystal.

  8. Atomistic simulation of shocks in single crystal and polycrystalline Ta

    Science.gov (United States)

    Bringa, E. M.; Higginbotham, A.; Park, N.; Tang, Y.; Suggit, M.; Mogni, G.; Ruestes, C. J.; Hawreliak, J.; Erhart, P.; Meyers, M. A.; Wark, J. S.

    2011-06-01

    Non-equilibrium molecular dynamics (MD) simulations of shocks in Ta single crystals and polycrystals were carried out using up to 360 million atoms. Several EAM and FS type potentials were tested up to 150 GPa, with varying success reproducing the Hugoniot and the behavior of elastic constants under pressure. Phonon modes were studied to exclude possible plasticity nucleation by soft-phonon modes, as observed in MD simulations of Cu crystals. The effect of loading rise time in the resulting microstructure was studied for ramps up to 0.2 ns long. Dislocation activity was not observed in single crystals, unless there were defects acting as dislocation sources above a certain pressure. E.M.B. was funded by CONICET, Agencia Nacional de Ciencia y Tecnología (PICT2008-1325), and a Royal Society International Joint Project award.

  9. Singly-resonant optical parametric oscillator based on KTA crystal

    Indian Academy of Sciences (India)

    S Das; S Gangopadhyay; C Ghosh; G C Bhar

    2005-01-01

    Tunable mid-infra-red radiation by singly resonant optical parametric oscillation based on KTA crystal pumped by multi-axial Gaussian shape beam from Q-switched Nd:YAG laser has been demonstrated. Threshold energy of oscillation at different idler wavelengths for different cavity length has been demonstrated. Single pass conversion efficiency of incident pump energy to infra-red wavelength has also been measured.

  10. Single particle detection in CMOS compatible photonic crystal nanobeam cavities.

    Science.gov (United States)

    Quan, Qimin; Floyd, Daniel L; Burgess, Ian B; Deotare, Parag B; Frank, Ian W; Tang, Sindy K Y; Ilic, Rob; Loncar, Marko

    2013-12-30

    We report the label-free detection of single particles using photonic crystal nanobeam cavities fabricated in silicon-on-insulator platform, and embedded inside microfluidic channels fabricated in poly-dimethylsiloxane (PDMS). Our system operates in the telecommunication wavelength band, thus leveraging the widely available, robust and tunable telecom laser sources. Using this approach, we demonstrated the detection of polystyrene nanoparticles with dimensions down to 12.5nm in radius. Furthermore, binding events of a single streptavidin molecule have been observed.

  11. Single Crystals of Organolead Halide Perovskites: Growth, Characterization, and Applications

    KAUST Repository

    Peng, Wei

    2017-04-01

    With the soaring advancement of organolead halide perovskite solar cells rising from a power conversion efficiency of merely 3% to more than 22% shortly in five years, researchers’ interests on this big material family have been greatly spurred. So far, both in-depth studies on the fundamental properties of organolead halide perovskites and their extended applications such as photodetectors, light emitting diodes, and lasing have been intensively reported. The great successes have been ascribed to various superior properties of organolead halide hybrid perovskites such as long carrier lifetimes, high carrier mobility, and solution-processable high quality thin films, as will be discussed in Chapter 1. Notably, most of these studies have been limited to their polycrystalline thin films. Single crystals, as a counter form of polycrystals, have no grain boundaries and higher crystallinity, and thus less defects. These characteristics gift single crystals with superior optical, electrical, and mechanical properties, which will be discussed in Chapter 2. For example, organolead halide perovskite single crystals have been reported with much longer carrier lifetimes and higher carrier mobilities, which are especially intriguing for optoelectronic applications. Besides their superior optoelectronic properties, organolead halide perovskites have shown large composition versatility, especially their organic components, which can be controlled to effectively adjust their crystal structures and further fundamental properties. Single crystals are an ideal platform for such composition-structure-property study since a uniform structure with homogeneous compositions and without distraction from grain boundaries as well as excess defects can provide unambiguously information of material properties. As a major part of work of this dissertation, explorative work on the composition-structure-property study of organic-cation-alloyed organolead halide perovskites using their single

  12. Angular correlation of annihilation photons in ice single crystals

    DEFF Research Database (Denmark)

    Mogensen, O. E.; Kvajic, G.; Eldrup, Morten Mostgaard

    1971-01-01

    Linear-slit angular-correlation curves were obtained at - 148 °C for the [0001], [10¯10], and [11¯20] directions in single crystals of ice. Besides the narrow central peak, pronounced narrow side peaks were also observed. They occurred at angles θ=2πℏgz/mc, where gz is the projection of reciproca...

  13. Coupling of single quantum dots to a photonic crystal waveguide

    DEFF Research Database (Denmark)

    Lund-Hansen, Toke; Stobbe, Søren; Julsgaard, Brian

    . An alternative approach is to couple the quantum dot directly to the propagating mode of a photonic waveguide. We demonstrate the coupling of single quantum dots to a photonic crystal waveguide using time-resolved spontaneous emission measurements. A pronounced effect is seen in the decay rates of dots coupled...

  14. Transverse Mode Multi-Resonant Single Crystal Transducer

    Science.gov (United States)

    Snook, Kevin A. (Inventor); Liang, Yu (Inventor); Luo, Jun (Inventor); Hackenberger, Wesley S. (Inventor); Sahul, Raffi (Inventor)

    2015-01-01

    A transducer is disclosed that includes a multiply resonant composite, the composite having a resonator bar of a piezoelectric single crystal configured in a d(sub 32) transverse length-extensional resonance mode having a crystallographic orientation set such that the thickness axis is in the (110) family and resonance direction is the (001) family.

  15. Some Debye temperatures from single-crystal elastic constant data

    Science.gov (United States)

    Robie, R.A.; Edwards, J.L.

    1966-01-01

    The mean velocity of sound has been calculated for 14 crystalline solids by using the best recent values of their single-crystal elastic stiffness constants. These mean sound velocities have been used to obtain the elastic Debye temperatures ??De for these materials. Models of the three wave velocity surfaces for calcite are illustrated. ?? 1966 The American Institute of Physics.

  16. Organic field-effect transistors using single crystals

    Directory of Open Access Journals (Sweden)

    Tatsuo Hasegawa and Jun Takeya

    2009-01-01

    Full Text Available Organic field-effect transistors using small-molecule organic single crystals are developed to investigate fundamental aspects of organic thin-film transistors that have been widely studied for possible future markets for 'plastic electronics'. In reviewing the physics and chemistry of single-crystal organic field-effect transistors (SC-OFETs, the nature of intrinsic charge dynamics is elucidated for the carriers induced at the single crystal surfaces of molecular semiconductors. Materials for SC-OFETs are first reviewed with descriptions of the fabrication methods and the field-effect characteristics. In particular, a benchmark carrier mobility of 20–40 cm2 Vs−1, achieved with thin platelets of rubrene single crystals, demonstrates the significance of the SC-OFETs and clarifies material limitations for organic devices. In the latter part of this review, we discuss the physics of microscopic charge transport by using SC-OFETs at metal/semiconductor contacts and along semiconductor/insulator interfaces. Most importantly, Hall effect and electron spin resonance (ESR measurements reveal that interface charge transport in molecular semiconductors is properly described in terms of band transport and localization by charge traps.

  17. Field-effect transistors on tetracene single crystals

    NARCIS (Netherlands)

    De Boer, R.W.I.; Klapwijk, T.M.; Morpurgo, A.F

    2003-01-01

    We report on the fabrication and electrical characterization of field-effect transistors at the surface of tetracene single crystals. We find that the mobility of these transistors reaches the room-temperature value of 0.4 cm2/V s. The nonmonotonous temperature dependence of the mobility, its weak g

  18. Three-dimensional charge transport in organic semiconductor single crystals.

    Science.gov (United States)

    He, Tao; Zhang, Xiying; Jia, Jiong; Li, Yexin; Tao, Xutang

    2012-04-24

    Three-dimensional charge transport anisotropy in organic semiconductor single crystals - both plates and rods (above and below, respectively, in the figure) - is measured in well-performing organic field-effect transistors for the first time. The results provide an excellent model for molecular design and device preparation that leads to good performance.

  19. Single-crystal semiconductor films grown on foreign substrates

    Science.gov (United States)

    Vohl, P.

    1966-01-01

    Intermediate alloy formed between foreign substrates and semiconductor material enable the growth of single crystal semiconductor films on the alloy layer. The melted film must not ball up on the surface of the substrate and neither chemically react nor alloy with the intermediate alloy formed on the substrate.

  20. Low field investigations of single crystal Bi(2212): DC magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, G.; Murphy, S.D.; Bhagat, S.M. (Center for Superconductivity Research and Dept. of Physics and Astronomy, Univ. of Maryland, College Park (USA))

    1989-12-01

    DC Magnetization measurements on micaceous Bi(2212) single crystals suggest that; 1. for T< or approx.25 K the material is a bulk Superconductor (SC), 2. as T is increased, the interlayer coupling weakens, until for T> or approx.55 K the lamina become independent. (orig.).

  1. Coupling of single quantum dots to a photonic crystal waveguide

    DEFF Research Database (Denmark)

    Lund-Hansen, Toke; Stobbe, Søren; Julsgaard, Brian;

    . An alternative approach is to couple the quantum dot directly to the propagating mode of a photonic waveguide. We demonstrate the coupling of single quantum dots to a photonic crystal waveguide using time-resolved spontaneous emission measurements. A pronounced effect is seen in the decay rates of dots coupled...

  2. TOPICAL REVIEW: Organic field-effect transistors using single crystals

    Science.gov (United States)

    Hasegawa, Tatsuo; Takeya, Jun

    2009-04-01

    Organic field-effect transistors using small-molecule organic single crystals are developed to investigate fundamental aspects of organic thin-film transistors that have been widely studied for possible future markets for 'plastic electronics'. In reviewing the physics and chemistry of single-crystal organic field-effect transistors (SC-OFETs), the nature of intrinsic charge dynamics is elucidated for the carriers induced at the single crystal surfaces of molecular semiconductors. Materials for SC-OFETs are first reviewed with descriptions of the fabrication methods and the field-effect characteristics. In particular, a benchmark carrier mobility of 20-40 cm2 Vs-1, achieved with thin platelets of rubrene single crystals, demonstrates the significance of the SC-OFETs and clarifies material limitations for organic devices. In the latter part of this review, we discuss the physics of microscopic charge transport by using SC-OFETs at metal/semiconductor contacts and along semiconductor/insulator interfaces. Most importantly, Hall effect and electron spin resonance (ESR) measurements reveal that interface charge transport in molecular semiconductors is properly described in terms of band transport and localization by charge traps.

  3. Evaluation of the surface strength of glass plates shaped by hot slumping process

    CERN Document Server

    Proserpio, L; Borsa, F; Citterio, O; Civitani, M; Ghigo, M; Pareschi, G; Salmaso, B; Sironi, G; Spiga, D; Tagliaferri, G; D'Este, A; Dall'Igna, R; Silvestri, M; Parodi, G; Martelli, F; Bavdaz, M; Wille, E

    2014-01-01

    The Hot Slumping Technology is under development by several research groups in the world for the realization of grazing-incidence segmented mirrors for X-ray astronomy, based on thin glass plates shaped over a mould at temperatures above the transformation point. The performed thermal cycle and related operations might have effects on the strength characteristics of the glass, with consequences on the structural design of the elemental optical modules and consecutively on the entire X-ray optic for large astronomical missions like IXO and ATHENA. The mechanical strength of glass plates after they underwent the slumping process was tested through destructive double-ring tests in the context of a study performed by the Astronomical Observatory of Brera with the collaboration of Stazione Sperimentale del Vetro and BCV Progetti. The entire study has been realized on more than 200 D263 Schott borosilicate glass specimens of dimension 100 mm x 100 mm and thickness 0.4 mm, either flat or bent at a Radius of Curvatur...

  4. Evaluation of the surface strength of glass plates shaped by hot slumping process

    Science.gov (United States)

    Proserpio, Laura; Basso, Stefano; Borsa, Francesco; Citterio, Oberto; Civitani, Marta; Ghigo, Mauro; Pareschi, Giovanni; Salmaso, Bianca; Sironi, Giorgia; Spiga, Daniele; Tagliaferri, Gianpiero; D'Este, Alberto; Dall'Igna, Roberto; Silvestri, Mirko; Parodi, Giancarlo; Martelli, Francesco; Bavdaz, Marcos; Wille, Eric

    2014-08-01

    Hot slumping technology is under development by several research groups in the world for the realization of grazing-incidence segmented mirrors for x-ray astronomy, based on thin glass plates shaped over a mold at temperatures above the transformation point. The performed thermal cycle and related operations might have effects on the strength of the glass, with consequences for the structural design of the elemental optical modules and, consequently, on the entire x-ray optic for large astronomical missions such as IXO and ATHENA. The mechanical strength of glass plates after they underwent the slumping process was tested through destructive double-ring tests in the context of a study performed by the Astronomical Observatory of Brera with the collaboration of Stazione Sperimentale del Vetro and BCV Progetti. The entire study was done on more than 200 D263 Schott borosilicate glass specimens of dimensions 100 mm×100 mm and a thickness 0.4 mm, either flat or bent at a radius of curvature of 1000 mm through the pressure-assisted hot slumping process developed by INAF-OAB. The collected experimental data have been compared with nonlinear finite element model analyses and treated with the Weibull statistic to assess the current IXO glass x-ray telescope design, in terms of survival probability, when subjected to static and acoustic loads characteristic of the launch phase. The paper describes the activities performed and presents the obtained results.

  5. Shaped crystal growth of langasite-type piezoelectric single crystals and their physical properties.

    Science.gov (United States)

    Yokota, Yuui; Yoshikawa, Akira; Futami, Yoshisuke; Sato, Masato; Tota, Kazushige; Onodera, Ko; Yanagida, Takayuki

    2012-09-01

    We have grown shape-controlled langasite-type crystals by the micro-pulling-down (μ-PD) method. Columnar shaped La(3)Ta(0.5)Ga(5.5)O(14) (LTG), Ca(3)NbGa(3)Si(2)O(14) (CNGS), Ca(3)TaGa(3)Si(2)O(14) (CTGS), Sr(3)NbGa(3)Si(2)O(14) (SNGS), and Sr(3)Ta- Ga(3)Si(2)O(14) (STGS) crystals were grown using a Pt-Rh crucible with a 3-mm-diameter columnar die at the bottom. All grown crystals showed high transparency except for the peripheral area and diameter of approximately 3 mm. The chemical phases at the central parts of the grown crystals were identified as a single phase of langasite-type structure and their lattice parameters were almost the same as those of crystals grown by the Czochralski (Cz) method; however, some impurity phases were observed in the peripheral area. In X-ray rocking curve measurements, the grown crystals indicated equivalent crystallinity to the crystal grown by the Cz method. The piezoelectric constant d(11) of the CNGS crystal was 3.98 pC/N; this value is well correlated with those of previous reports.

  6. Understanding the Cubic Phase Stabilization and Crystallization Kinetics in Mixed Cations and Halides Perovskite Single Crystals.

    Science.gov (United States)

    Xie, Li-Qiang; Chen, Liang; Nan, Zi-Ang; Lin, Hai-Xin; Wang, Tan; Zhan, Dong-Ping; Yan, Jia-Wei; Mao, Bing-Wei; Tian, Zhong-Qun

    2017-03-08

    The spontaneous α-to-δ phase transition of the formamidinium-based (FA) lead halide perovskite hinders its large scale application in solar cells. Though this phase transition can be inhibited by alloying with methylammonium-based (MA) perovskite, the underlying mechanism is largely unexplored. In this Communication, we grow high-quality mixed cations and halides perovskite single crystals (FAPbI3)1-x(MAPbBr3)x to understand the principles for maintaining pure perovskite phase, which is essential to device optimization. We demonstrate that the best composition for a perfect α-phase perovskite without segregation is x = 0.1-0.15, and such a mixed perovskite exhibits carrier lifetime as long as 11.0 μs, which is over 20 times of that of FAPbI3 single crystal. Powder XRD, single crystal XRD and FT-IR results reveal that the incorporation of MA(+) is critical for tuning the effective Goldschmidt tolerance factor toward the ideal value of 1 and lowering the Gibbs free energy via unit cell contraction and cation disorder. Moreover, we find that Br incorporation can effectively control the perovskite crystallization kinetics and reduce defect density to acquire high-quality single crystals with significant inhibition of δ-phase. These findings benefit the understanding of α-phase stabilization behavior, and have led to fabrication of perovskite solar cells with highest efficiency of 19.9% via solvent management.

  7. Mechanism of the emergence of the photo-EMF upon silicon liquid crystal-single crystal contact

    Science.gov (United States)

    Budagov, K. M.; Guseinov, A. G.; Pashaev, B. G.

    2017-03-01

    The effect light has on a silicon liquid crystal-single crystal contact at different temperatures of the surface doping of silicon, and when BaTiO3 nanoparticles are added to the composition of a liquid crystal, is studied. The mechanism of the emergence of the photo-EMF in the liquid crystal-silicon structure is explained.

  8. Low-dissipation cavity optomechanics in single-crystal diamond

    CERN Document Server

    Mitchell, Matthew; Lake, David P; Barclay, Paul E

    2015-01-01

    Single-crystal diamond cavity optomechanical devices are a promising example of a hybrid quantum system: by coupling mechanical resonances to both light and electron spins, they can enable new ways for photons to control solid state qubits. However, creating devices from high quality bulk diamond chips is challenging. Here we demonstrate single-crystal diamond cavity optomechanical devices that can enable photon-phonon-spin coupling. Cavity optomechanical coupling to $2\\,\\text{GHz}$ frequency ($f_\\text{m}$) mechanical resonances is observed. In room temperature ambient conditions, the resonances have a record combination of low dissipation ($Q_\\text{m} > 9000$) and high frequency, with $Q_\\text{m}\\cdot f_\\text{m} \\sim 1.9\\times10^{13}$ sufficient for room temperature single phonon coherence. The system is nearly sideband resolved, and radiation pressure is used to excite $\\sim 31\\,\\text{pm}$ amplitude mechanical self-oscillations that can drive diamond color centre electron spin transitions.

  9. Spatially resolved micro-photoluminescence imaging of porphyrin single crystals

    Science.gov (United States)

    Marin, Dawn M.; Castaneda, Jose; Kaushal, Meesha; Kaouk, Ghallia; Jones, Daniel S.; Walter, Michael G.

    2016-08-01

    We describe the collection of both time-resolved and steady-state micro-photoluminescence data from solution-grown single crystals of 5,15-bis(4-carbomethoxyphenyl)porphyrin (BCM2PP). Linking molecular orientation and structure with excited-state dynamics is crucial for engineering efficient organic solar cells, light-emitting diodes, and related molecular electronics. Photoluminescence features of single porphyrin crystals were imaged using a laser scanning confocal microscope equipped with time-correlated single photon counting (TCSPC). We show enhanced exciton lifetimes (τs1 = 2.6 ns) and stronger steady-state emission in crystalline BCM2PP samples relative to semicrystalline thin films (τs1 = 1.8 ns).

  10. Role of crystal orientation on chemical mechanical polishing of single crystal copper

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Aibin, E-mail: abzhu@mail.xjtu.edu.cn; He, Dayong; Luo, Wencheng; Liu, Yangyang

    2016-11-15

    Highlights: • The role of crystal orientation in cooper CMP by quasi-continuum was studied. • The atom displacement diagrams were obtained and analyzed. • The stress distribution diagrams and load-displacement curves were analyzed. • This research is helpful to revealing the material removal mechanism of CMP. - Abstract: The material removal mechanism of single crystal copper in chemical mechanical polishing (CMP) has not been intensively investigated. And the role of crystal orientation in CMP of single crystal cooper is not quite clear yet. Quasi-continuum method was adopted in this paper to simulate the process of nano-particles grinding on single crystal copper in CMP process. Three different crystal orientations, i.e. x[100]y[001], x[001]y[110] and x[–211]y[111], were chosen for analysis. The atom displacement diagrams, stress distribution diagrams and load-displacement curves were obtained. After analyzing the deformation mechanism, residual stress of the work piece material and cutting force, results showed that, the crystal orientation of work piece has great influence on the deformation characteristics and surface quality of work piece during polishing. In the A(001)[100] orientation, the residual stress distribution after polishing is deeper, and the stress is larger than that in the B(110)[001] and C(111)[–211] orientations. And the average tangential cutting force in the A(001)[100] orientation is much larger than those in the other two crystal orientation. This research is helpful to revealing the material removal mechanism of CMP process.

  11. Transport Properties of Bi2S3 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    H.T.Shaban; M.M.Nassary; M.S.El-Sadek

    2008-01-01

    Bi2S3 single crystals were grown by using a modification of Bridgman method. Measurements of the electrical conductivity, Hall effect and thermoelectric power (TEP) were preformed in two crystallographic directions(parallel and perpendicular to the c-axis). The measurements showed that the electrical conductivity, Hall mobility, and Seebeck coefficient have anisotropic nature. From these measurements some physical parameters were estimated and the crystals showed n-type of conduction mechanism. Also, values of the energy gap were found to be different in the two directions.

  12. Impurity centers in LiF:Cu{sup +} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Nepomnyashchikh, A I; Shalaev, A A; Subanakov, A K; Paklin, A S; Bobina, N S; Myasnikova, A S; Shendrik, R, E-mail: alshal@igc.irk.ru

    2010-11-15

    The single crystals LiF with copper impurity were grown by Czochralski method. The concentrations of Cu in the crystals were 0,0004-0,002%. In order to determine a copper valence impurity, measurements of the ESR, emission, excitation and absorption spectra were performed. We found emission peak at 410 nm and excitation peak at 250 nm. In agreement with reference, these peaks point to presence of Cu{sup +} in our samples. The mechanisms of capture and recombination providing process of thermoluminescence were recognized.

  13. Organic single-crystal field-effect transistors

    Directory of Open Access Journals (Sweden)

    Colin Reese

    2007-03-01

    Full Text Available Organic molecular crystals hold great promise for the rational development of organic semiconductor materials. Their long-range order not only reveals the performance limits of organic materials, but also provides unique insight into their intrinsic transport properties. The field-effect transistor (FET has served as a versatile tool for electrical characterization of many facets of their performance. In the last few years, breakthroughs in single-crystal FET fabrication techniques have enabled the realization of field-effect mobilities far surpassing amorphous Si, observation of the Hall effect in an organic material, and the study of transport as an explicit function of molecular packing and chemical structure.

  14. Crystal growth, electrical and photophysical properties of Tl2S layered single crystals

    Indian Academy of Sciences (India)

    A M Badr; H A Elshaikh; I M Ashraf

    2009-05-01

    The Tl2S compound was prepared in a single crystal form using a special local technique, and the obtained crystals were analysed by X-ray diffraction. For the resultant crystals, the electrical properties (electrical conductivity and Hall effect) and steady-state photoconductivity were elucidated in this work. The electrical measurements extend from 170 to 430 K, where it was found that ⊥ = 8.82 × 10−5 Sm-1 when current flow direction makes right angle to the cleavage plane of the crystals. In the same range of temperatures, it was found that ∥ = 4.73 × 10−5 Sm-1 when the current flow is parallel to the cleavage plane. In line with the investigated range of temperatures, the widths of the band gaps were calculated and discussed as also the results of the electrical conductivity and Hall effect measurements. In addition, the anisotropy of the electrical conductivity (⊥/∥) for the obtained crystals was also studied in this work. Finally the photosensitivity was calculated for different levels of illumination as a result of the photoconductivity measurements, which showed that the recombination process in Tl2S single crystals is a monomolecular process.

  15. The crystallization and optical properties of LiNbO3 single crystals

    Directory of Open Access Journals (Sweden)

    SLOBODANKA NIKOLIC

    2000-06-01

    Full Text Available LiNbO3 single crystals were grown by the Czochralski technique in an air atmosphere. The critical crystal diameter Dc = 1.5 cm and the critical rate of rotation wc = 35 rpm were calculated from the dynamic of fluids equations for buoyancy-driven and forced convections under which the shape of the melt/crystal interface changed. The domain inversion was carried out at 1473 K using a 10 min 3.75 V/cm electric field. The obtained crystals were cut, polished and etched to determine the presence of dislocations and single domain structures. The lattice parameters a = 0.51494 nm, c = 1.38620 nm and V = 0.3186 nm3 were determined by X-ray powder diffraction. The optical properties were studied by infrared spectroscopy in the wave number range 20 - 5000 cm-1. With decreasing temperature, an atypical behaviour of the phonon modes, due to the ferroelectric properties of LiNbO3 single crystal, could be seen. The optical constants were calculated by Kramers-Kronig analysis and the value of the critical temperature was estimated. The obtained results are discussed and compared with published data.

  16. Strain gradient crystal plasticity analysis of a single crystal containing a cylindrical void

    DEFF Research Database (Denmark)

    Borg, Ulrik; Kysar, J.W.

    2007-01-01

    The effects of void size and hardening in a hexagonal close-packed single crystal containing a cylindrical void loaded by a far-field equibiaxial tensile stress under plane strain conditions are studied. The crystal has three in-plane slip systems oriented at the angle 60 degrees with respect...... to one another. Finite element simulations are performed using a strain gradient crystal plasticity formulation with an intrinsic length scale parameter in a non-local strain gradient constitutive framework. For a vanishing length scale parameter the non-local formulation reduces to a local crystal...... to three times higher for smaller void sizes than for larger void sizes in the non-local material....

  17. Crystallization of inorganic nonlinear optical zinc di-magnesium chloro sulphate (ZDMCS) single crystal

    Science.gov (United States)

    Arivuselvi, R.; Ruban Kumar, A.

    2017-02-01

    The growth of inorganic zinc di-magnesium chloro sulphate (ZDMCS) nonlinear optical material from low temperature evaporation technique at ambient temperature has been reported. The dimension of harvested crystal is 28×10×2 mm3 and is possess rectangular shape morphology. The single crystal X-ray diffraction studies confirmed that the grown crystal belongs to the system of trigonal. The S-Cl stretching vibrations and Mg2+ ions present in the sample were observed by FTIR spectrometer. The cut-off wavelength of the grown crystal is about 203 nm is found by UV-visible absorption spectrum. The nonlinear optical efficiency was determined by powder Kurtz Perry technique. EDAX spectrum confirms the presence of elements within the material. Dielectric nature of the sample was analyzed for the frequency range 50 Hz to 5 MHz at different temperatures. The mechanical behaviour of the title compound was investigated using Vicker's microhardness tester.

  18. Semiconducting polymer single crystals and devices (Conference Presentation)

    Science.gov (United States)

    Dong, Huanli

    2016-11-01

    Highly ordered organic semiconductors in solid state with optimal molecular packing are critical to their electrical performance. Single crystals with long-range molecular orders and nearly perfect molecular packing are the best candidates, which already have been verified to exhibit the highest performance whether based on inorganic or small organic materials. However, in comparison, preparing high quality polymer crystals remains a big challenge in polymer science because of the easy entanglements of the long and flexible polymer chains during self-assembly process, which also significantly limits the development of their crystalline polymeric electronic devices. Here we have carried out systematical investigations to prepare high quality semiconducting polymers and high performance semiconducting polymer crystal optoelectronic devices have been successfully fabricated. The semiconducting polymeric devices demonstrate significantly enhanced charge carreir transport compared to their thin films, and the highest carreir mobiltiy could be approcahing 30 cm2 V-1s-1, one of the highest mobiltiy values for polymer semiconductors.

  19. Neutron transmission and reflection at a copper single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Adib, M.; Maayouf, R.M.A.; Abdel-Kawy, A.; Fayek, M.; Habib, N. (Atomic Energy Establishment, Cairo (Egypt). Reactor and Neutron Physics Dept.); Wahba, M. (Ain Shams Univ., Cairo (Egypt). Dept. of Engineering Physics and Mathematics)

    1991-06-01

    Neutron transmission and reflection at a copper single crystal cut along the (111) plane were studied with the fixed-scattering-angle spectrometer installed at the ET-RR-1 reactor. The transmission was measured for neutron wavelengths between 0.15 and 0.46 nm and various orientations of the (111) plane with respect to the incident beam. When used as a neutron band pass filter, the crystal is optimally oriented when the neutron beam is incident parallel to the (111) direction. The reflectivity was measured for the (111) plane at 45deg with respect to the incident beam. The results were found to be in reasonable agreement with a value predicted for the reflected intensity at an imperfect crystal with finite absorption. (orig.).

  20. Resonant magnetic properties of gadolinium-gallium garnet single crystals

    Science.gov (United States)

    Bedyukh, A. R.; Danilov, V. V.; Nechiporuk, A. Yu.; Romanyuk, V. F.

    1999-03-01

    The results of experimental investigations of resonant magnetic properties of gadolinium-gallium garnet (GGG) single crystals at temperatures 4.2-300 K in the frequency range 1.6-9.3 GHz are considered. It is found that magnetic losses in GGG are determined by the initial splitting of energy levels for gadolinium ions in the garnet crystal lattice and by the dipole broadening. The width and shape of the electron paramagnetic resonance (EPR) line in the GGG crystal, whose asymmetry is manifested most strongly at low frequencies, can be explained by the influence of these factors. Magnetic losses in GGG increase with frequency and upon cooling. It is found that the EPR linewidth increases considerably with decreasing temperature due to the presence of rapidly relaxing impurities.

  1. Size effects in single crystal thin films : nonlocal crystal plasticity simulations

    NARCIS (Netherlands)

    Yefimov, S; van der Giessen, E

    2005-01-01

    Stress relaxation in single crystalline thin films on substrates subjected to thermal loading is studied using a recently proposed nonlocal continuum crystal plasticity theory. The theory is founded on a statistical-mechanics description of the collective behaviour of dislocations in multiple slip,

  2. A new material for single crystal modulators: BBO

    Science.gov (United States)

    Bammer, F.; Schumi, T.; Petkovsek, R.

    2011-06-01

    Single crystal photo-elastic modulators (SCPEM) are based on a single piezo-electric crystal which is electrically excited on a resonance frequency such that the resulting resonant oscillation causes a modulated artificial birefringence due to the photo-elastic effect. Polarized light experience in such a crystal a strong modulation of polarization, which, in connection with a polarizer, can be used for Q-switching of lasers with pulse repetition frequencies in the range of 100- 1000 kHz. A particularly advantageous configuration is possible with crystals from the symmetry class 3m. Besides LiTaO3 and LiNbO3, both already well explored as SCPEM-materials, we introduce now BBO, which offers a very low absorption in the near infrared region and is therefore particularly suited for Q-switching of solid state lasers. We demonstrate first results of such a BBO-modulator with the dimensions 8.6 x 4.05 x 4.5mm in x-, y-, z- direction, which offers a useful resonance and polarization modulation at 131.9 kHz. Since the piezo-electric effect is small, the voltage amplitude for achieving Q-switching for an Nd:YAG-laser is expected to be in the range of 100V. Nevertheless it is a simple and robust device to achieve Q-switching with a high fixed repetition rate for high power solid state lasers.

  3. Converting ceria polyhedral nanoparticles into single-crystal nanospheres.

    Science.gov (United States)

    Feng, Xiangdong; Sayle, Dean C; Wang, Zhong Lin; Paras, M Sharon; Santora, Brian; Sutorik, Anthony C; Sayle, Thi X T; Yang, Yi; Ding, Yong; Wang, Xudong; Her, Yie-Shein

    2006-06-09

    Ceria nanoparticles are one of the key abrasive materials for chemical-mechanical planarization of advanced integrated circuits. However, ceria nanoparticles synthesized by existing techniques are irregularly faceted, and they scratch the silicon wafers and increase defect concentrations. We developed an approach for large-scale synthesis of single-crystal ceria nanospheres that can reduce the polishing defects by 80% and increase the silica removal rate by 50%, facilitating precise and reliable mass-manufacturing of chips for nanoelectronics. We doped the ceria system with titanium, using flame temperatures that facilitate crystallization of the ceria yet retain the titania in a molten state. In conjunction with molecular dynamics simulation, we show that under these conditions, the inner ceria core evolves in a single-crystal spherical shape without faceting, because throughout the crystallization it is completely encapsulated by a molten 1- to 2-nanometer shell of titania that, in liquid state, minimizes the surface energy. The principle demonstrated here could be applied to other oxide systems.

  4. Frictional properties of single crystals HMX, RDX and PETN explosives.

    Science.gov (United States)

    Wu, Y Q; Huang, F L

    2010-11-15

    The frictional properties of single crystals of cyclotetramethylene tetranitramine (HMX), cyclotrimethylene trinitramine (RDX) and pentaerythritol tetranitrate (PETN) secondary explosives are examined using a sensitive friction machine. The explosive crystals used for the measurements are at least 3.5 mm wide. The friction coefficients between crystals of the same explosive (i.e., HMX on HMX, etc.), crystals of different explosives (i.e., HMX on RDX, etc.), and each explosive and a well-polished gauge steel surface are determined. The frictional surfaces are also studied under an environmental scanning electron microscope (ESEM) to analyze surface microstructural changes under increasing loading forces. The friction coefficients vary considerably with increasing normal loading forces and are particularly sensitive to slider shapes, crystal roughness and the mechanical properties of both the slider and the sample. With increasing loading forces, most friction experiments show surface damage, consisting of grooves, debris, and nano-particles, on both the slider and sample. In some cases, a strong evidence of a localized molten state is found in the central region of the friction track. Possible mechanisms that affect the friction coefficient are discussed based on microscopic observations. Copyright © 2010 Elsevier B.V. All rights reserved.

  5. Dispersion of optical activity of magnesium sulfite hexahydrate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dimov, T; Bunzarov, Zh; Iliev, I; Petkova, P; Tzoukrovski, Y, E-mail: dimov@shu-bg.ne

    2010-11-01

    The magnesium sulfite hexahydrate (MgSO{sub 3}.6H{sub 2}O) crystals are unique because they are the only representative (with sodium periodate) of the crystallographic class C{sub 3} (without a center of symmetry). The crystal symmetry suggests presence of nonlinearity, piezo- and pyro-electric properties and gyrotropy as well. Single crystals of MgSO{sub 3}.6H{sub 2}O (pure and doped with Ni, Co and Zn) for the time being are grown only by the original method developed in the Laboratory for Crystal growth at the Faculty of Physics in Sofia University. The first results of optical activity of pure MgSO{sub 3}.6H{sub 2}O and Zn doped MgSO{sub 3}.6H{sub 2}O crystals are described and analyzed in a wide spectral range. The optical activity manifests itself in the direction (0001) as a rotation of the polarization plane.

  6. Nanofluidics of Single-crystal Diamond Nanomechanical Resonators

    CERN Document Server

    Kara, V; Atikian, H; Yakhot, V; Loncar, M; Ekinci, K L

    2015-01-01

    Single-crystal diamond nanomechanical resonators are being developed for countless applications. A number of these applications require that the resonator be operated in a fluid, i.e., a gas or a liquid. Here, we investigate the fluid dynamics of single-crystal diamond nanomechanical resonators in the form of nanocantilevers. First, we measure the pressure-dependent dissipation of diamond nanocantilevers with different linear dimensions and frequencies in three gases, He, N$_2$, and Ar. We observe that a subtle interplay between the length scale and the frequency governs the scaling of the fluidic dissipation. Second, we obtain a comparison of the surface accommodation of different gases on the diamond surface by analyzing the dissipation in the molecular flow regime. Finally, we measure the thermal fluctuations of the nanocantilevers in water, and compare the observed dissipation and frequency shifts with theoretical predictions. These findings set the stage for developing diamond nanomechanical resonators o...

  7. Oriented hydroxyapatite single crystals produced by the electrodeposition method

    Energy Technology Data Exchange (ETDEWEB)

    Santos, E.A. dos, E-mail: euler@ufs.br [INSA - Groupe Ingenierie des Surfaces, 24, Bld de la Victoire, 67084 Strasbourg (France); IPCMS - Departement de Surfaces et Interfaces, 23, rue du Loess, BP 43, 67034 Strasbourg (France); Moldovan, M.S. [INSA - Groupe Ingenierie des Surfaces, 24, Bld de la Victoire, 67084 Strasbourg (France); IPCMS - Departement de Surfaces et Interfaces, 23, rue du Loess, BP 43, 67034 Strasbourg (France); Jacomine, L. [INSA - Groupe Ingenierie des Surfaces, 24, Bld de la Victoire, 67084 Strasbourg (France); Mateescu, M. [IS2M - Equipe Interaction Surface-Matiere Vivant, 15, rue Jean Starcky, BP 2488, 68057 Mulhouse (France); Werckmann, J. [IPCMS - Departement de Surfaces et Interfaces, 23, rue du Loess, BP 43, 67034 Strasbourg (France); Anselme, K. [IS2M - Equipe Interaction Surface-Matiere Vivant, 15, rue Jean Starcky, BP 2488, 68057 Mulhouse (France); Mille, P.; Pelletier, H. [INSA - Groupe Ingenierie des Surfaces, 24, Bld de la Victoire, 67084 Strasbourg (France)

    2010-05-25

    We propose here the use of cathodic electrodeposition as tool to fabricate implant coatings consisting in nano/micro single crystals of hydroxyapatite (HA), preferentially orientated along the c-axis. Coating characterization is the base of this work, where we discuss the mechanisms related to the deposition of oriented hydroxyapatite thin films. It is shown that when deposited on titanium alloys, the HA coating is constituted by two distinct regions with different morphologies: at a distance of few microns from the substrate, large HA single crystals are oriented along the c-axis and appear to grow up from a base material, consisting in an amorphous HA. This organized system has a great importance for cell investigation once the variables involved in the cell/surface interaction are reduced. The use of such systems could give a new insight on the effect of particular HA orientation on the osteoblast cells.

  8. Frequency dispersion of flexoelectricity in PMN-PT single crystal

    Directory of Open Access Journals (Sweden)

    Longlong Shu

    2017-01-01

    Full Text Available The mechanism of the recent discovered enhanced flexoelectricity in perovskites has brought about numerous controversies which still remain unclear. In this paper, we employed relaxor 0.68Pb(Mg2/3Nb1/3O3 -0.32PbTiO3 (PMN-PT single crystals for study. The observed flexoelectric coefficient in PMN-PT single crystal reaches up to 100 μC/m, and in a relative low frequency range, exhibits an abnormal frequency dispersion phenomenon with a positive relationship with frequency. Such frequency dispersion regulation is different from the normal relaxation behavior that usually occur a time delay, and hence proves the flexoelectricity acting more like bulk effect rather than surface effect in this kind of materials.

  9. Growth of EuO single crystals at reduced temperatures

    Science.gov (United States)

    Ramirez, Daniel C.; Besara, Tiglet; Whalen, Jeffrey B.; Siegrist, Theo

    2017-01-01

    Single crystals of (E u1 -xB ax)O have been grown in a molten barium-magnesium metal flux at temperatures up to 1000 °C, producing single crystals of (E u1 -xB ax)O with barium doping levels ranging from x =0.03 to x =0.25 . Magnetic measurements show that the ferromagnetic Curie temperature TC correlates with the Ba doping levels, and a modified Heisenberg model was used to describe the stoichiometry dependence of TC. Extrapolation of the results indicates that a sample with Ba concentration of x =0.72 should have a TC of 0 K, potentially producing a quantum phase transition in this material.

  10. High pressure single crystal and powder XRD study for neighborite

    Science.gov (United States)

    Liu, H.

    2016-12-01

    After Murakami et al. (2004) identified the post-perovskite (ppv) phase transition in MgSiO3 perovskite (pv) at pressures and temperatures consistent with the onset of Earth's D" layer, lots of post-perovskite type phase transitions were founded in other similar systems. These discoveries provided a better understanding of heterogeneous structures and seismic anisotropy observed in the controversial region of the lower mantle. With previous experimental evidence showing the analogue system of neighborite NaMgF3 will transform from pv to ppv at 30 GPa, we performed high quality single crystal XRD experiment, which led to a more precise structure determination. Using helium as pressure medium, one metastable low symmetric phase before the pv-ppv structure transition was discovered, whose total energy was calculated as well. The comparison between single crystal and powder XRD data will be presented, and potential application will be discussed.

  11. Synthesis and characterization of single-crystal strontium hexaboride nanowires.

    Science.gov (United States)

    Jash, Panchatapa; Nicholls, Alan W; Ruoff, Rodney S; Trenary, Michael

    2008-11-01

    Catalyst-assisted growth of single-crystal strontium hexaboride (SrB6) nanowires was achieved by pyrolysis of diborane (B2H6) over SrO powders at 760-800 degrees C and 400 mTorr in a quartz tube furnace. Raman spectra demonstrate that the nanowires are SrB6, and transmission electron microscopy along with selected area diffraction indicate that the nanowires consist of single crystals with a preferred [001] growth direction. Electron energy loss data combined with the TEM images indicate that the nanowires consist of crystalline SrB 6 cores with a thin (1 to 2 nm) amorphous oxide shell. The nanowires have diameters of 10-50 nm and lengths of 1-10 microm.

  12. Annealing Effect on Photovoltages of Quartz Single Crystals

    Institute of Scientific and Technical Information of China (English)

    TIAN Lu; ZHAO Song-Qing; ZHAO Kun

    2010-01-01

    @@ We investigate the photovoltaic effects of quartz single crystals annealed at high temperatures in ambient atmosphere.The open-circuit photovoltages and surface morphologies strongly depend on the heating treatments.When the annealing temperature increases from room temperature to 900℃,the rms roughness of quartz single crystal wafers increases from 0.207 to 1.011 nm.In addition,the photovoltages decrease from 1.994#V at room temperature to 1.551 μ V after treated at 500℃,and then increase up to 9.8μV after annealed at 900℃.The inner mechanism of the present photovoltaic response and surface morphologies is discussed.

  13. Electrical conductivity and dielectric properties of potassium sulfamate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A.S.; Iype, L.; Rajesh, R. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam (India); Varughese, G. [Department of Physics, Catholicate College, Pathanamthitta, Kerala (India); Joseph, G. [Department of Physics, Sacred Heart College, Thevera, Cochin, Kerala (India); Louis, G. [Department of Physics, Cochin University of Science and Technology, Cochin (India)

    2011-10-15

    Single crystals of potassium sulfamate are grown by the method of slow evaporation at constant temperature. AC electrical conductivity of potassium sulfamate is measured in the temperature range 300-430 K and in the frequency region between 100 Hz and 3 MHz along the a, b and c-axes. Complex impedance spectroscopy is used to investigate the frequency response of the electrical properties of the potassium sulfamate single crystal. Temperature variation of AC conductivity and dielectric measurements show a slope change around 345 K for both heating and cooling run and this anomaly is attributed as phase transition, which is well supported by the DSC measurements. Value of loss tangent in the temperature region 330-400 K is found to be very low. Activation energies for the conduction process are calculated along the a, b and c-axes. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Single crystal neutron diffraction study of triglycine sulphate revisited

    Indian Academy of Sciences (India)

    Rajul Ranjan Choudhury; R Chitra

    2008-11-01

    In order to get the exact hydrogen-bonding scheme in triglycine sulphate (TGS), which is an important hydrogen bonded ferroelectric, a single crystal neutron diffraction study was undertaken. The structure was refined to an -factor of [2] = 0.034. Earlier neutron structure of TGS was reported with a very limited data set and large standard deviations. The differences between the present and the earlier reported neutron structure of TGS are discussed.

  15. The Herbertsmithite Hamiltonian: {mu}SR measurements on single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ofer, Oren [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T2A3 (Canada); Keren, Amit [Department of Physics, Technion, Haifa 32000 (Israel); Brewer, Jess H [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T1Z1 (Canada); Han, Tianheng H; Lee, Young S, E-mail: oren@triumf.ca [Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2011-04-27

    We present transverse field muon spin rotation/relaxation measurements on single crystals of the spin-1/2 kagome antiferromagnet Herbertsmithite. We find that the spins are more easily polarized when the field is perpendicular to the kagome plane. We demonstrate that the difference in magnetization between the different directions cannot be accounted for by Dzyaloshinskii-Moriya-type interactions alone and that anisotropic axial interaction is present.

  16. Ion implantation induced blistering of rutile single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Bing-Xi [School of Physics, Shandong University, Jinan, Shandong 250100 (China); Jiao, Yang [College of Physics and Electronics, Shandong Normal University, Jinan, Shandong 250100 (China); Guan, Jing [School of Physics, Shandong University, Jinan, Shandong 250100 (China); Wang, Lei [School of Physics, Shandong University, Jinan, Shandong 250100 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (China)

    2015-07-01

    The rutile single crystals were implanted by 200 keV He{sup +} ions with a series fluence and annealed at different temperatures to investigate the blistering behavior. The Rutherford backscattering spectrometry, optical microscope and X-ray diffraction were employed to characterize the implantation induced lattice damage and blistering. It was found that the blistering on rutile surface region can be realized by He{sup +} ion implantation with appropriate fluence and the following thermal annealing.

  17. Microstructure evolution of single crystal copper wires in cold drawing

    Institute of Scientific and Technical Information of China (English)

    CHEN; Jian; YAN; Wen; WANG; XueYan; FAN; XinHui

    2007-01-01

    The deformation microstructure evolution of single crystal copper wires produced by OCC method has been studied with the help of TEM, EBSD and OM. The results show that there are a small number of dendrites and twins in the undeformed single crystal copper wires. However, it is difficult to observe these dendrites in deformed single crystal copper wires. The structure evolution of deformed single crystal copper wires during drawing process can be divided into three stages. When the true strain is lower than 0.94, macroscopic subdivision of grains is not evident, and the microscopic evolution of deformed structure is that the cells are formed and elongated in drawn direction. When the true strain is between 0.94 and 1.96, macroscopic subdivision of grains takes place, and the number of microbands located on {111} and cell blocks is much more than that with the true strain lower than 0.94. When the true strain is larger than 1.96, the macroscopic subdivision of grains becomes more evident than that with the true strain between 0.94 and 1.96, and S-bands structure and lamellar boundaries will be formed. From EBSD analysis, it is found that part of texture resulting from solidifying is transformed into and due to shear deformation, but texture component is still kept in majority. When the true strain is 0.94, the misorientation angle of dislocation boundaries resulting from deformation is lower than 14°. However, when the true strain arrives at 1.96, the misorientation angle of some boundaries will be greater than 50°, and the peak of misorientation angle distribution produced by texture evolution is located in the range between 25° and 30°.

  18. Study of diffusion of Ag in Cu single crystals

    CERN Document Server

    Wang, R

    2002-01-01

    4.0 MeV sup 7 Li sup + sup + RBS and AES were used for investigations of thermal diffusion of Ag in Cu single crystals. The annealing of samples was carried out in vacuum in the temperature range from 498 to 613 K. The element depth concentration profiles transformed from RBS spectra indicate that the diffusion of Ag into Cu is a typical volume diffusion. The Arrhenius parameters corresponding to the diffusion were obtained.

  19. Interfacial dislocation motion and interactions in single-crystal superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Raabe, D. [Max Planck Inst. fur Eisenforshung. Dusseldorf (Germany); Roters, F. [Max Planck Inst. fur Eisenforshung. Dusseldorf (Germany); Arsenlis, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-10-01

    The early stage of high-temperature low-stress creep in single-crystal superalloys is characterized by the rapid development of interfacial dislocation networks. Although interfacial motion and dynamic recovery of these dislocation networks have long been expected to control the subsequent creep behavior, direct observation and hence in-depth understanding of such processes has not been achieved. Incorporating recent developments of discrete dislocation dynamics models, we simulate interfacial dislocation motion in the channel structures of single-crystal superalloys, and investigate how interfacial dislocation motion and dynamic recovery are affected by interfacial dislocation interactions and lattice misfit. Different types of dislocation interactions are considered: self, collinear, coplanar, Lomer junction, glissile junction, and Hirth junction. The simulation results show that strong dynamic recovery occurs due to the short-range reactions of collinear annihilation and Lomer junction formation. The misfit stress is found to induce and accelerate dynamic recovery of interfacial dislocation networks involving self-interaction and Hirth junction formation, but slow down the steady interfacial motion of coplanar and glissile junction forming dislocation networks. The insights gained from these simulations on high-temperature low-stress creep of single-crystal superalloys are also discussed.

  20. Physical properties of CuAlO 2 single crystal

    Science.gov (United States)

    Brahimi, R.; Bellal, B.; Bessekhouad, Y.; Bouguelia, A.; Trari, M.

    2008-09-01

    CuAlO 2 single crystal elaborated by the flux method is a narrow band gap semiconductor crystallizing in the delafossite structure (SG R3¯m). Oxygen insertion in the layered lattice generates p-type conductivity where most holes are trapped in surface-polaron states. The detailed photoelectrochemical characterization and electrochemical impedance spectroscopy (EIS) have been reported for the first time on the single crystal. The study is confined in the basal plan and reversible oxygen insertion is evidenced from the intensity potential characteristics. The oxide is characterized by an excellent chemical stability; the semi-logarithmic plot gave a corrosion potential of-0.82 V SCE and an exchange current density of 0.022 μA cm -2 in KCl (0.5 M) electrolyte. The capacitance measurement ( C-2- V) shows a linear behavior from which a flat band potential of +0.42 V SCE and a doping density NA of 10 16 cm -3 have been determined. The valence band, located at 5.24 eV (0.51 V SCE) below vacuum, is made up of Cu-3d orbital. The Nyquist plot exhibits a pseudo-semicircle whose center is localized below the real axis with an angle of 20°. This can be attributed to a single relaxation time of the electrical equivalent circuit and a constant phase element (CPE). The absence of straight line indicates that the process is under kinetic control.

  1. Constitutive Model for an FCC Single-Crystal Material

    Institute of Scientific and Technical Information of China (English)

    DING Zhi-ping; LIU Yi-lun; YIN Ze-yong; YANG Zhi-guo; CHENG Xiao-ming

    2006-01-01

    Talking into account the effects that the components of tension stresses couple with components of torsion stresses when off-axis loads are applied to orthotropic materials.Hill's yield criterion for plastically orthotropic solids is modified by adding an invariant that is composed of the product item of quadratic components of the deviatoric siress tensor,and a new yield criteflon is put forward in terms of the characteristics of the face-centered cubic(FCC) single-crystal material.The correlation of prediction and experiments is very good.and the new criterion is used to predict the yield stresses of an intemal single-crystal,Nickel-based superalloy,DD3,which is more accurate than that Of Hill's at 760°C.Equivalent stress and strain that adapt to the new criterion are defined.Thinking of the yield function as a plastic potential function from the associated flow rule.the elastic-plastic constitutive model for the FCC single-crystal material is constructed,and the corresponding elastic-plastic matrix iseduced.The new yield criterion and its equivalent stress and strain will be reduced to Von Mises' yield criterion and corresponding equivalent stress and strain for isotropic materials.

  2. Chiral multichromic single crystals for optical devices (LDRD 99406).

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Richard Alan; Felix, Ana M. (University of New Mexico, Albuquerque, NM)

    2006-12-01

    This report summarizes our findings during the study of a novel system that yields multi-colored materials as products. This system is quite unusual as it leads to multi-chromic behavior in single crystals, where one would expect that only a single color would exist. We have speculated that these novel solids might play a role in materials applications such as non-linear optics, liquid crystal displays, piezoelectric devices, and other similar applications. The system examined consisted of a main-group alkyl compound (a p block element such as gallium or aluminum) complexed with various organic di-imines. The di-imines had substituents of two types--either alkyl or aromatic groups attached to the nitrogen atoms. We observed that single crystals, characterized by X-ray crystallography, were obtained in most cases. Our research during January-July, 2006, was geared towards understanding the factors leading to the multi-chromic nature of the complexes. The main possibilities put forth initially considered (a) the chiral nature of the main group metal, (b) possible reduction of the metal to a lower-valent, radical state, (c) the nature of the ligand(s) attached to the main group metal, and (d) possible degradation products of the ligand leading to highly-colored products. The work carried out indicates that the most likely explanation considered involves degradation of the aromatic ligands (a combination of (c) and (d)), as the experiments performed can clearly rule out (a) and (b).

  3. Single crystal plasticity by modeling dislocation density rate behavior

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Benjamin L [Los Alamos National Laboratory; Bronkhorst, Curt [Los Alamos National Laboratory; Beyerlein, Irene [Los Alamos National Laboratory; Cerreta, E. K. [Los Alamos National Laboratory; Dennis-Koller, Darcie [Los Alamos National Laboratory

    2010-12-23

    The goal of this work is to formulate a constitutive model for the deformation of metals over a wide range of strain rates. Damage and failure of materials frequently occurs at a variety of deformation rates within the same sample. The present state of the art in single crystal constitutive models relies on thermally-activated models which are believed to become less reliable for problems exceeding strain rates of 10{sup 4} s{sup -1}. This talk presents work in which we extend the applicability of the single crystal model to the strain rate region where dislocation drag is believed to dominate. The elastic model includes effects from volumetric change and pressure sensitive moduli. The plastic model transitions from the low-rate thermally-activated regime to the high-rate drag dominated regime. The direct use of dislocation density as a state parameter gives a measurable physical mechanism to strain hardening. Dislocation densities are separated according to type and given a systematic set of interactions rates adaptable by type. The form of the constitutive model is motivated by previously published dislocation dynamics work which articulated important behaviors unique to high-rate response in fcc systems. The proposed material model incorporates thermal coupling. The hardening model tracks the varying dislocation population with respect to each slip plane and computes the slip resistance based on those values. Comparisons can be made between the responses of single crystals and polycrystals at a variety of strain rates. The material model is fit to copper.

  4. Large-lattice-parameter perovskite single-crystal substrates

    Science.gov (United States)

    Uecker, Reinhard; Bertram, Rainer; Brützam, Mario; Galazka, Zbigniew; Gesing, Thorsten M.; Guguschev, Christo; Klimm, Detlef; Klupsch, Michael; Kwasniewski, Albert; Schlom, Darrell G.

    2017-01-01

    The pseudobinary system LaLuO3-LaScO3 was explored in hopes of discovering new perovskite-type substrates with pseudocubic lattice parameters above 4 Å. A complete solid solution of the type (LaLuO3)1-x(LaScO3)x forms between the end members LaLuO3 and LaScO3, enabling large single crystals of (LaLuO3)1-x(LaScO3)x to be grown from the melt. A single crystal with x≈0.34 was demonstrated. Considering the maximum thermal load of the iridium crucibles appropriate for Czochralski growth of this solid solution, the theoretically maximum achievable x-value is 0.67. Based on the phase diagram determined, it is anticipated that single crystals with pseudocubic lattice constants between 4.09 and 4.18 Å can be grown in this system by the Czochralski method.

  5. Single mode dye-doped polymer photonic crystal lasers

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Buss, Thomas; Smith, Cameron

    2010-01-01

    Dye-doped polymer photonic crystal (PhC) lasers fabricated by combined nanoimprint and photolithography are studied for their reproducibility and stability characteristics. We introduce a phase shift in the PhC lattice that substantially improves the yield of single wavelength emission. Single mode...... emission and reproducibility of laser characteristics are important if the lasers are to be mass produced in, e. g., optofluidic sensor chips. The fabrication yield is above 85% with highly reproducible wavelengths (within 0.5%), and the temperature dependence on the wavelength is found to be -0.045 or -0...

  6. Diamond turning of Si and Ge single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Blake, P.; Scattergood, R.O.

    1988-12-01

    Single-point diamond turning studies have been completed on Si and Ge crystals. A new process model was developed for diamond turning which is based on a critical depth of cut for plastic flow-to-brittle fracture transitions. This concept, when combined with the actual machining geometry for single-point turning, predicts that {open_quotes}ductile{close_quotes} machining is a combined action of plasticity and fracture. Interrupted cutting experiments also provide a meant to directly measure the critical depth parameter for given machining conditions.

  7. Influence of solvents on the habit modification of alpha lactose monohydrate single crystals

    Science.gov (United States)

    Parimaladevi, P.; Srinivasan, K.

    2013-02-01

    Restricted evaporation of solvent method was adopted for the growth of alpha lactose monohydrate single crystals from different solvents. The crystal habits of grown crystals were analysed. The form of crystallization was confirmed by powder x-ray diffraction analysis. Thermal behaviour of the grown crystals was studied by using differential scanning calorimetry.

  8. Acquisition of Single Crystal Growth and Characterization Equipment

    Energy Technology Data Exchange (ETDEWEB)

    Maple, M. Brian; Zocco, Diego A.

    2008-12-09

    Final Report for DOE Grant No. DE-FG02-04ER46178 'Acquisition of Single Crystal Growth and Characterization Equipment'. There is growing concern in the condensed matter community that the need for quality crystal growth and materials preparation laboratories is not being met in the United States. It has been suggested that there are too many researchers performing measurements on too few materials. As a result, many user facilities are not being used optimally. The number of proficient crystal growers is too small. In addition, insufficient attention is being paid to the enterprise of finding new and interesting materials, which is the driving force behind much of condensed matter research and, ultimately, technology. While a detailed assessment of this situation is clearly needed, enough evidence of a problem already exists to compel a general consensus that the situation must be addressed promptly. This final report describes the work carried out during the last four years in our group, in which a state-of-the-art single crystal growth and characterization facility was established for the study of novel oxides and intermetallic compounds of rare earth, actinide and transition metal elements. Research emphasis is on the physics of superconducting (SC), magnetic, heavy fermion (HF), non-Fermi liquid (NFL) and other types of strongly correlated electron phenomena in bulk single crystals. Properties of these materials are being studied as a function of concentration of chemical constituents, temperature, pressure, and magnetic field, which provide information about the electronic, lattice, and magnetic excitations at the root of various strongly correlated electron phenomena. Most importantly, the facility makes possible the investigation of material properties that can only be achieved in high quality bulk single crystals, including magnetic and transport phenomena, studies of the effects of disorder, properties in the clean limit, and spectroscopic and

  9. Self-templated synthesis of single-crystal and single-domain ferroelectric nanoplates

    KAUST Repository

    Chao, Chunying

    2012-08-15

    Free-standing single-crystal PbTiO 3 nanoplates (see picture) were synthesized by a facile hydrothermal method. A "self-templated" crystal growth is presumed to lead to the formation of the PbTiO 3 nanoplates, which have ferroelectric single-domain structures, whose polarization areas can be manipulated by writing and reading. The nanoplates are also effective catalysts for the oxidation of carbon monoxide. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Effect of Solidification Condition on Microstructure and Mechanical Properties of Single Crystal Superalloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    CMSX-2 single crystals with different primary dendrite arm spacing were obtained on directional solidification apparatus with high temperature gradient (250 K/cm). The microstructure and elevated temperature stress rupture properties of these single crystals were examined and analyzed.

  11. Advanced piezoelectric single crystal based transducers for naval sonar applications

    Science.gov (United States)

    Snook, Kevin A.; Rehrig, Paul W.; Hackenberger, Wesley S.; Jiang, Xiaoning; Meyer, Richard J., Jr.; Markley, Douglas

    2006-03-01

    Transducers incorporating single crystal piezoelectric Pb(Mg 1/3Nb 2/3) x-1Ti xO 3 (PMN-PT) exhibit significant advantages over ceramic piezoelectrics such as PZT, including both high electromechanical coupling (k 33 > 90%) and piezoelectric coefficients (d 33 > 2000 pC/N). Conventional orientation gives inherently larger bandwidth and output power than PZT ceramics, however, the anisotropy of the crystal also allows for tailoring of the performance by orienting the crystal along different crystallographic axes. This attribute combined with composition refinements can be used to improve thermal or mechanical stability, which is important in high power, high duty cycle sonar applications. By utilizing the "31" resonance mode, the high power performance of PMN-PT can be improved over traditional "33" mode single crystal transducers, due to an improved aspect ratio. Utilizing novel geometries, effective piezoelectric constants of -600 pC/N to -1200 pC/N have been measured. The phase transition point induced by temperature, pre-stress or field is close to that in the "33" mode, and since the prestress is applied perpendicular to the poling direction in "31" mode elements, they exhibit lower loss and can therefore be driven harder. The high power characteristics of tonpilz transducers can also be affected by the composition of the PMN-PT crystal. TRS modified the composition of PMN-PT to improve the thermal stability of the material, while keeping the loss as low as possible. Three dimensional modeling shows that the useable bandwidth of these novel compositions nearly equals that of conventional PMN-PT. A decrease in the source level of up to 6 dB was calculated, which can be compensated for by the higher drive voltages possible.

  12. Employing a cylindrical single crystal in gas-surface dynamics.

    Science.gov (United States)

    Hahn, Christine; Shan, Junjun; Liu, Ying; Berg, Otto; Kleijn, Aart W; Juurlink, Ludo B F

    2012-03-21

    We describe the use of a polished, hollow cylindrical nickel single crystal to study effects of step edges on adsorption and desorption of gas phase molecules. The crystal is held in an ultra-high vacuum apparatus by a crystal holder that provides axial rotation about a [100] direction, and a crystal temperature range of 89 to 1100 K. A microchannel plate-based low energy electron diffraction/retarding field Auger electron spectrometer (AES) apparatus identifies surface structures present on the outer surface of the cylinder, while a separate double pass cylindrical mirror analyzer AES verifies surface cleanliness. A supersonic molecular beam, skimmed by a rectangular slot, impinges molecules on a narrow longitudinal strip of the surface. Here, we use the King and Wells technique to demonstrate how surface structure influences the dissociation probability of deuterium at various kinetic energies. Finally, we introduce spatially-resolved temperature programmed desorption from areas exposed to the supersonic molecular beam to show how surface structures influence desorption features.

  13. Magnesium single crystals for biomedical applications grown in vertical Bridgman apparatus

    Science.gov (United States)

    Salunke, Pravahan; Joshi, Madhura; Chaswal, Vibhor; Zhang, Guangqi; Rosenbaum, Leonard A.; Dowling, Kevin; Decker, Paul; Shanov, Vesselin

    2016-10-01

    This paper describes successful efforts to design, build, test, and utilize a single crystal apparatus using the Bridgman approach for directional solidification. The created instrument has been successfully tested to grow magnesium single crystals from melt. Preliminary mechanical tests carried out on these single crystals indicate unique and promising properties, which can be harnessed for biomedical applications.

  14. Large pyramid shaped single crystals of BiFeO{sub 3} by solvothermal synthesis method

    Energy Technology Data Exchange (ETDEWEB)

    Sornadurai, D.; Ravindran, T. R.; Paul, V. Thomas; Sastry, V. Sankara [Condensed Matter Physics Division, Materials Science Group, Physical Metallurgy Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India); Condensed Matter Physics Division, Materials Science Group (India)

    2012-06-05

    Synthesis parameters are optimized in order to grow single crystals of multiferroic BiFeO{sub 3}. 2 to 3 mm size pyramid (tetrahedron) shaped single crystals were successfully obtained by solvothermal method. Scanning electron microscopy with EDAX confirmed the phase formation. Raman scattering spectra of bulk BiFeO3 single crystals have been measured which match well with reported spectra.

  15. Organic single-crystal light-emitting field-effect transistors

    NARCIS (Netherlands)

    Hotta, Shu; Yamao, Takeshi; Bisri, Satria Zulkarnaen; Takenobu, Taishi; Iwasa, Yoshihiro

    2014-01-01

    Growth and characterisation of single crystals constitute a major field of materials science. In this feature article we overview the characteristics of organic single-crystal light-emitting field-effect transistors (OSCLEFETs). The contents include the single crystal growth of organic semiconductor

  16. Room-Temperature Tensile Behavior of Oriented Tungsten Single Crystals with Rhenium in Dilute Solid Solution

    Science.gov (United States)

    1966-01-01

    SINGLE CRYSTALS WITH RHENIUM IN DILUTE SOLID SOLUTION Sby M. Garfinkle Lewis Research Center Cleveland, Ohio 20060516196 NATIONAL AERONAUTICS AND...WITH RHENIUM IN DILUTE SOLID SOLUTION By M. Garfinkle Lewis Research Center Cleveland, Ohio NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by...ORIENTED TUNGSTEN SINGLE CRYSTALS WITH RHENIUM IN DILUTE SOLID SOLUTION * by M. Garfinkle Lewis Research Center SUMMARY Tungsten single crystals

  17. Crystal structure and magnetization of a Co3B2O6 single crystal

    Science.gov (United States)

    Kazak, N. V.; Platunov, M. S.; Ivanova, N. B.; Knyazev, Yu. V.; Bezmaternykh, L. N.; Eremin, E. V.; Vasil'ev, A. D.; Bayukov, O. A.; Ovchinnikov, S. G.; Velikanov, D. A.; Zubavichus, Ya. V.

    2013-07-01

    The crystal structure and magnetic properties of Co3B2O6 single crystals are studied. Orthorhombic symmetry with space group Pnnm is detected at room temperature. The measurements of static magnetization and dynamic magnetic susceptibility reveal two magnetic anomalies at T 1 = 33 K and T 2 = 10 K and an easy-axis magnetic anisotropy. The effective magnetic moment indicates a high-spin state of the Co2+ ion. A spin-flop transition is found at low temperatures and H sf = 23 kOe. EXAFS spectra of the K-edge absorption of Co are recorded at various temperatures, the temperature-induced changes in the parameters of the local environment of cobalt are analyzed, and the effective Co-Co and Co-O distances are determined. The magnetic interactions in the crystal are analyzed in terms of an indirect coupling model.

  18. Strength anomaly in B2 FeAl single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimi, K.; Hanada, S.; Yoo, M.H. [Oak Ridge National Lab., TN (United States); Matsumoto, N. [Tohoku Univ. (Japan). Graduate School

    1994-12-31

    Strength and deformation microstructure of B2 Fe-39 and 48%Al single crystals (composition given in atomic percent), which were fully annealed to remove frozen-in vacancies, have been investigated at temperatures between room temperature and 1073K. The hardness of as-homogenized Fe-48Al is higher than that of as-homogenized Fe-39Al while after additional annealing at 698K the hardness of Fe-48Al becomes lower than that of Fe-39Al. Fe-39Al single crystals slowly cooled after homogenizing at a high temperature were deformed in compression as a function of temperature and crystal orientation. A peak of yield strength appears around 0.5T{sub m} (T{sub m} = melting temperature). The orientation dependence of the critical resolved shear stress does not obey Schmid`s law even at room temperature and is quite different from that of b.c.c. metals and B2 intermetallics at low temperatures. At the peak temperature slip transition from <111>-type to <001>-type is found to occur macroscopically and microscopically, while it is observed in TEM that some of the [111] dislocations decompose into [101] and [010] on the (1096I) plane below the peak temperature. The physical sources for the positive temperature dependence of yield stress of B2 FeAl are discussed based on the obtained results.

  19. Growth and Characterization of Lead-free Piezoelectric Single Crystals

    Directory of Open Access Journals (Sweden)

    Philippe Veber

    2015-11-01

    Full Text Available Lead-free piezoelectric materials attract more and more attention owing to the environmental toxicity of lead-containing materials. In this work, we review our first attempts of single crystal grown by the top-seeded solution growth method of BaTiO3 substituted with zirconium and calcium (BCTZ and (K0.5Na0.5NbO3 substituted with lithium, tantalum, and antimony (KNLSTN. The growth methodology is optimized in order to reach the best compositions where enhanced properties are expected. Chemical analysis and electrical characterizations are presented for both kinds of crystals. The compositionally-dependent electrical performance is investigated for a better understanding of the relationship between the composition and electrical properties. A cross-over from relaxor to ferroelectric state in BCTZ solid solution is evidenced similar to the one reported in ceramics. In KNLSTN single crystals, we observed a substantial evolution of the orthorhombic-to-tetragonal phase transition under minute composition changes.

  20. Structural peculiarities of single crystal diamond needles of nanometer thickness

    Science.gov (United States)

    Orekhov, Andrey S.; Tuyakova, Feruza T.; Obraztsova, Ekaterina A.; Loginov, Artem B.; Chuvilin, Andrey L.; Obraztsov, Alexander N.

    2016-11-01

    Diamond is attractive for various applications due to its unique mechanical and optical properties. In particular, single crystal diamond needles with high aspect ratios and sharp apexes of nanometer size are demanded for different types of optical sensors including optically sensing tip probes for scanning microscopy. This paper reports on electron microscopy and Raman spectroscopy characterization of the diamond needles having geometrically perfect pyramidal shapes with rectangular atomically flat bases with (001) crystallography orientation, 2-200 nm sharp apexes, and with lengths from about 10-160 μm. The needles were produced by selective oxidation of (001) textured polycrystalline diamond films grown by chemical vapor deposition. Here we study the types and distribution of defects inside and on the surface of the single crystal diamond needles. We show that sp3 type point defects are incorporated into the volume of the diamond crystal during growth, while the surface of the lateral facets is enriched by multiple extended defects. Nitrogen addition to the reaction mixture results in increase of the growth rate on {001} facets correlated with the rise in the concentration of sp3 type defects.

  1. Structural and magnetic studies on copper succinate dihydrate single crystals

    Indian Academy of Sciences (India)

    M P BINITHA; P P PRADYUMNAN

    2017-09-01

    Single crystals of copper succinate dihydrate were grown in silica gel by slow diffusion of copper chloride tosodium metasilicate gel impregnated with succinic acid. The grown crystal was subjected to single crystal X-ray diffractionstudies. In its structure each copper atom is penta co-ordinated to oxygen atoms of four succinate oxygens and oxygenof co-ordinated water molecule. The four bis-bidendate succinate anions form syn–syn bridges among two copper atomsto form a polymeric two-dimensional chain. From room temperature vibrating sample magnetometer (VSM) studies themagnetic moment of the material is calculated as 1.35 Bohr magneton (BM), indicating antiferromagnetic interaction betweencopper atoms and can be explained as due to the orbital overlap of the bridging ligand and the two copper atoms in syn-synorientation. A strong bonding of the magnetic orbital of equatorially oriented Cu atom on both sides of the exchange pathway(Cu–O-C-O–Cu) leads to the anti-ferromagnetic interaction.

  2. Single-Photon Source for Quantum Information Based on Single Dye Molecule Fluorescence in Liquid Crystal Host

    Energy Technology Data Exchange (ETDEWEB)

    Lukishova, S.G.; Knox, R.P.; Freivald, P.; McNamara, A.; Boyd, R.W.; Stroud, Jr., C.R.; Schmid, A.W.; Marshall, K.L.

    2006-08-18

    This paper describes a new application for liquid crystals: quantum information technology. A deterministically polarized single-photon source that efficiently produces photons exhibiting antibunching is a pivotal hardware element in absolutely secure quantum communication. Planar-aligned nematic liquid crystal hosts deterministically align the single dye molecules which produce deterministically polarized single (antibunched) photons. In addition, 1-D photonic bandgap cholesteric liquid crystals will increase single-photon source efficiency. The experiments and challenges in the observation of deterministically polarized fluorescence from single dye molecules in planar-aligned glassy nematic-liquid-crystal oligomer as well as photon antibunching in glassy cholesteric oligomer are described for the first time.

  3. Electronic properties of graphene-single crystal diamond heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Fang; Thuong Nguyen, Thuong; Golsharifi, Mohammad; Amakubo, Suguru; Jackman, Richard B., E-mail: r.jackman@ucl.ac.uk [London Centre for Nanotechnology and Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, London WC1H 0AH (United Kingdom); Loh, K. P. [Department of Chemistry, National University of Singapore, 3 Science Drive, Singapore 117543 (Singapore)

    2013-08-07

    Single crystal diamond has been used as a substrate to support single layer graphene grown by chemical vapor deposition methods. It is possible to chemically functionalise the diamond surface, and in the present case H-, F-, O-, and N-group have been purposefully added prior to graphene deposition. The electronic properties of the resultant heterostructures vary strongly; a p-type layer with good mobility and a band gap of ∼0.7 eV is created when H-terminated diamond layers are used, whilst a layer with more metallic-like character (high carrier density and low carrier mobility) arises when N(O)-terminations are introduced. Since it is relatively easy to pattern these functional groups on the diamond surface, this suggests that this approach may offer an exciting route to 2D device structures on single layer graphene sheets.

  4. Rolling-contact deformation of MgO single crystals

    Science.gov (United States)

    Dufrane, K. F.; Glaeser, W. A.

    1976-01-01

    Magnesium oxide single crystals were used as a model bearing material and deformed by rolling contact with a steel ball 0.64 cm in diameter. A dependence of depth of slip on rolling velocity which persisted with increasing numbers of rolling-contact cycles was discovered. The track width, track hardness and dislocation interactions as observed by transmission electron microscopy all increased in a consistent manner with increasing cycles. The rolling-contact state of stress produces a high density of dislocations in a localized zone. Dislocation interaction in this zone produces cleavage-type cracks after a large number of rolling-contact cycles. The orientation of the crystal influences the character of dislocation accumulation.

  5. α-Lead tellurite from single-crystal data.

    Science.gov (United States)

    Zavodnik, Valery E; Ivanov, Sergey A; Stash, Adam I

    2008-02-06

    The crystal structure of the title compound, α-PbTeO(3) (PTO), has been reported previously by Mariolacos [Anz. Oesterr. Akad. Wiss. Math. Naturwiss. Kl. (1969), 106, 128-130], refined on powder data. The current determination at room temperature from data obtained from single crystals grown by the Czochralski method shows a significant improvement in the precision of the geometric parameters when all atoms have been refined anisotropically. The selection of a centrosymmetric (C2/c) structure model was confirmed by the second harmonic generation test. The asymmetric unit contains three formula units. The structure of PTO is built up of three types of distorted [PbO(x)] polyhedra (x = 7 and 9) which share their O atoms with TeO(3) pyramidal units. These main anionic polyhedra are responsible for establishing the two types of tunnel required for the stereochemical activity of the lone pairs of the Pb(2+) and Te(4+) cations.

  6. α-Lead tellurite from single-crystal data

    Directory of Open Access Journals (Sweden)

    Adam I. Stash

    2008-03-01

    Full Text Available The crystal structure of the title compound, α-PbTeO3 (PTO, has been reported previously by Mariolacos [Anz. Oesterr. Akad. Wiss. Math. Naturwiss. Kl. (1969, 106, 128–130], refined on powder data. The current determination at room temperature from data obtained from single crystals grown by the Czochralski method shows a significant improvement in the precision of the geometric parameters when all atoms have been refined anisotropically. The selection of a centrosymmetric (C2/c structure model was confirmed by the second harmonic generation test. The asymmetric unit contains three formula units. The structure of PTO is built up of three types of distorted [PbOx] polyhedra (x = 7 and 9 which share their O atoms with TeO3 pyramidal units. These main anionic polyhedra are responsible for establishing the two types of tunnel required for the stereochemical activity of the lone pairs of the Pb2+ and Te4+ cations.

  7. Shape-memory effect in Co-Ni single crystal

    Institute of Scientific and Technical Information of China (English)

    周伟敏; 刘岩; 张少宗; 江伯鸿

    2004-01-01

    The thermal shape-memory effect at room temperature for Co-32% Ni(mass fraction) magnetic shape memory alloy of single crystal was presented. When compressing the sample along the [001] direction at room temperature, strain can be recovered to some extent during later heating and the recovery rate varies with the pre-strain.But no obvious recoverable strain can be obtained along other crystal directions. For the thermal-mechanical training of the sample along [001], the recovery strain decreases obviously during the second round of compress and nearly no recovery happens after the third round of compress. A possible mechanism based on reversible motions of Shockley partial dislocations was proposed.

  8. Water weakening in experimentally deformed milky quartz single crystals

    Science.gov (United States)

    Stunitz, H.; Thust, A.; Kilian, R.; Heilbronner, R.; Behrens, H.; Tarantola, A.; Fitz Gerald, J. D.

    2015-12-01

    Natural single crystals of quartz have been experimentally deformed in two orientations: (1) normal to one prism-plane, (2) In O+ orientation at temperatures of 900 and 1000°C, pressures of 1.0 and 1.5 GPa, and strain rates of ~1 x 10-6s-1. The starting material is milky quartz, consisting of dry quartz (H2O contents of recycling of H2O between FI´s, dislocation generation at very small fluid inclusions, incorporation of structurally bound H into dislocation cores, and release of H2O from dislocations back into FI´s during recovery. Cracking and crack healing play an important role in the recycling process and imply a close interrelationship between brittle and crystal plastic deformation. The H2O weakening by this process is of a disequilibrium nature and thus depends on the amount of H2O available.

  9. Multiband Effects on -FeSe single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic C.; Lei, H.; Graf, D.; Hu, R.; Ryu, H.; Choi, E.S.; Tozer, S.W.

    2012-03-01

    We present the upper critical fields {mu}{sub 0}H{sub c2}(T) and Hall effect in {beta}-FeSe single crystals. The {mu}{sub 0}H{sub c2}(T) increases as the temperature is lowered for fields applied parallel and perpendicular to (101), the natural growth facet of the crystal. The {mu}{sub 0}H{sub c2}(T) for both field directions and the anisotropy at low temperature increase under pressure. Hole carriers are dominant at high magnetic fields. However, the contribution of electron-type carriers is significant at low fields and low temperature. Our results show that multiband effects dominate {mu}{sub 0}H{sub c2}(T) and electronic transport in the normal state.

  10. Monitoring Lidocaine Single-Crystal Dissolution by Ultraviolet Imaging

    DEFF Research Database (Denmark)

    Ostergaard, Jesper; Ye, Fengbin; Rantanen, Jukka

    2011-01-01

    Dissolution critically affects the bioavailability of Biopharmaceutics Classification System class 2 compounds. When unexpected dissolution behaviour occurs, detailed studies using high information content technologies are warranted. In the present study, an evaluation of real‐time ultraviolet (UV......) imaging for conducting single‐crystal dissolution studies was performed. Using lidocaine as a model compound, the aim was to develop a setup capable of monitoring and quantifying the dissolution of lidocaine into a phosphate buffer, pH 7.4, under stagnant conditions. A single crystal of lidocaine...... was placed in the quartz dissolution cell and UV imaging was performed at 254 nm. Spatially and temporally resolved mapping of lidocaine concentration during the dissolution process was achieved from the recorded images. UV imaging facilitated the monitoring of lidocaine concentrations in the dissolution...

  11. Microhardness studies on nonlinear optical -alanine single crystals

    Indian Academy of Sciences (India)

    R Hanumantharao; S Kalainathan

    2013-06-01

    Vickers and Knoop microhardness tests were carried out on grown -alanine single crystals by slow evaporation technique over a load range of 10–50 g on selected broad (2 0 3) plane. Vickers (v) and Knoop (k) microhardness for the above loads were found to be in the range of 60–71 kg/mm2 and 35–47 kg/mm2, respectively. Vickers microhardness number (v) and Knoop microhardness number (k) were found to increase with increasing load. Meyer’s index number () calculated from v shows that the material belongs to the soft material category. Using Wooster’s empirical relation, the elastic stiffness constant (11) was calculated from Vickers hardness values. Young’s modulus was calculated using Knoop hardness values. Hardness anisotropy has been observed in accordance with the orientation of the crystal.

  12. Micromechanical Behavior of Single-Crystal Superalloy with Different Crystal Orientations by Microindentation

    Directory of Open Access Journals (Sweden)

    Jinghui Li

    2015-01-01

    Full Text Available In order to investigate the anisotropic micromechanical properties of single-crystal nickel-based superalloy DD99 of four crystallographic orientations, (001, (215, (405, and (605, microindentation test (MIT was conducted with different loads and loading velocities by a sharp Berkovich indenter. Some material parameters reflecting the micromechanical behavior of DD99, such as microhardness H, Young’s modulus E, yield stress σy, strain hardening component n, and tensile strength σb, can be obtained from load-displacement relations. H and E of four different crystal planes evidently decrease with the increase of h. The reduction of H is due to dislocation hardening while E is related to interplanar spacing and crystal variable. σy of (215 is the largest among four crystal planes, followed by (605, and (001 has the lowest value. n of (215 is the lowest, followed by (605, and that of (001 is the largest. Subsequently, a simplified elastic-plastic material model was employed for 3D microindentation simulation of DD99 with various crystal orientations. The simulation results agreed well with experimental, which confirmed the accuracy of the simplified material model.

  13. Single Crystal Structure Determination of Alumina to 1 Mbar

    Science.gov (United States)

    Dong, H.; Zhang, L.; Prakapenka, V.; Mao, H.

    2014-12-01

    Aluminum oxide (Al2O3) is an important ceramic material and a major oxide in the earth. Additionally, alumina is a widely used pressure standard in static high-pressure experiments (Cr3+-bearing corundum, ruby). The changes of its crystal structure with pressure (P) and temperature (T) are important for its applications and understanding its physical properties in the deep Earth. There have been numerous reports on the high P-T polymorphs of alumina. Previous theoretical calculations and experiments suggest that the crystal structure of Al2O3 evolves greatly at high P-T. In this study, we used the newly developed multigrain crystallography method combined with single-crystal x-ray diffraction analysis technique for the structure determination of alumina at high P-T to provide single-crystal structure refinement for high-pressure phases of Al2O3. Alumina powder was mixed with ~10% Pt and Ne was used as both pressure transmitting media and thermal insulating layers during laser-heating. Coarse-grained aggregates of Al2O3 were synthesized in a laser-heated diamond anvil cell. The structure change of Al2O3 was monitored by in situ x-ray diffraction at ~1 Mbar and 2700 K. The results allow us to distinguish the structural differences between the Rh2O3 (II) structure (space group Pbcn) and perovskite structure (space group Pbnm) for the first high-pressure phase of Al2O3. More detailed results will be discussed in the later work.

  14. Modeling the anisotropic shock response of single-crystal RDX

    Science.gov (United States)

    Luscher, Darby

    Explosives initiate under impacts whose energy, if distributed homogeneously throughout the material, translates to temperature increases that are insufficient to drive the rapid chemistry observed. Heterogeneous thermomechanical interactions at the meso-scale (i.e. between single-crystal and macroscale) leads to the formation of localized hot spots. Direct numerical simulations of mesoscale response can contribute to our understanding of hot spots if they include the relevant deformation mechanisms that are essential to the nonlinear thermomechanical response of explosive molecular crystals. We have developed a single-crystal model for the finite deformation thermomechanical response of cyclotrimethylene trinitramine (RDX). Because of the low symmetry of RDX, a complete description of nonlinear thermoelasticity requires a careful decomposition of free energy into components that represent the pressure-volume-temperature (PVT) response and the coupling between isochoric deformation and both deviatoric and hydrostatic stresses. An equation-of-state (EOS) based on Debye theory that defines the PVT response was constructed using experimental data and density functional theory calculations. This EOS replicates the equilibrium states of phase transformation from alpha to gamma polymorphs observed in static high-pressure experiments. Lattice thermoelastic parameters defining the coupled isochoric free energy were obtained from molecular dynamics calculations and previous experimental data. Anisotropic crystal plasticity is modeled using Orowan's expression relating slip rate to dislocation density and velocity. Details of the theory will be presented followed by discussion of simulations of flyer plate impact experiments, including recent experiments diagnosed with in situ X-ray diffraction at the Advanced Photon Source. Impact conditions explored within the experimental effort have spanned shock pressures ranging from 1-10 GPa for several crystallographic orientations

  15. Fabrication of ZnO Bi-crystals with twist boundaries using Co doped ZnO single crystals

    CERN Document Server

    Ohashi, N; Ohgaki, T; Tsurumi, T; Fukunaga, O; Haneda, H; Tanaka, J

    1999-01-01

    Zn O single crystals doped with Co were grown by using a flux method and their electrical properties were investigated by Hall effect. Then, these crystals were polished with diamond paste and bonded to form bi-crystal by hot pressing under a pressure of 10 MPa at 1000 .deg. C. The bi-crystals showed nonlinear I-V curves, and the curvature of I-V relation agreed with that for Co-doped polycrystalline ZnO.

  16. Pressure-induced superconductivity in Bi single crystals

    Science.gov (United States)

    Li, Yufeng; Wang, Enyu; Zhu, Xiyu; Wen, Hai-Hu

    2017-01-01

    Measurements on resistivity and magnetic susceptibility have been carried out for Bi single crystals under pressures up to 10.5 GPa. The temperature dependent resistivity shows a semimetallic behavior at ambient and low pressures (below about 1.6 GPa). This is followed by an upturn of resistivity in the low temperature region when the pressure is increased, which is explained as a semiconductor behavior. This feature gradually gets enhanced up to a pressure of about 2.52 GPa. Then a nonmonotonic temperature dependent resistivity appears upon further increasing pressure, which is accompanied by a strong suppression to the low temperature resistivity upturn. Simultaneously, a superconducting transition occurs at about 3.92 K under a pressure of about 2.63 GPa. With further increasing pressure, a second superconducting transition emerges at about 7 K under about 2.8 GPa. For these two superconducting states, the superconductivity induced magnetic screening volumes are quite large. As the pressure further increases to 8.1 GPa, we observe the third superconducting transition at about 8.2 K. The resistivity measurements under magnetic field allow us to determine the upper critical fields μ0Hc 2 of the superconducting phases. The upper critical field for the phase with Tc=3.92 K is extremely low. Based on the Werthamer-Helfand-Hohenberg (WHH) theory, the estimated value of μ0Hc 2 for this phase is about 0.103 T, while the upper critical field for the phase with Tc=7 K is very high with a value of about 4.56 T. Finally, we present a pressure dependent phase diagram of Bi single crystals. Our results reveal the interesting and rich physics in bismuth single crystals under high pressure.

  17. Characteristics of photoconductivity in thallium monosulfide single crystals

    Indian Academy of Sciences (India)

    I M Ashraf; H A Elshaikh; A M Badr

    2007-03-01

    This work elucidates the photoconductivity (PC) of thallium monosulfide single crystals. Results are obtained in the 77-300 K temperature range, 1500-4500 V lx excitation intensity, 6-18 V applied voltage, and in the 640-1500 nm wavelength range. Both the ac-photoconductivity (ac-PC) and the spectral distribution of the photocurrent are studied in different values of light intensity, applied voltage and temperature. Dependencies of carrier lifetime on light intensity, applied voltage and temperature are also investigated as a result of the ac-PC measurements. The temperature dependence of the energy gap width was described by studying the dc-photoconductivity (dc-PC).

  18. Exciton optical transitions in a hexagonal boron nitride single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Museur, L. [Laboratoire de Physique des Lasers - LPL, CNRS UMR 7538, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Brasse, G.; Maine, S.; Ducastelle, F.; Loiseau, A. [ONERA - Laboratoire d' Etude des Microstructures - LEM, ONERA-CNRS, UMR 104, BP 72, 92322 Chatillon Cedex (France); Pierret, A. [ONERA - Laboratoire d' Etude des Microstructures - LEM, ONERA-CNRS, UMR 104, BP 72, 92322 Chatillon Cedex (France); CEA-CNRS, Institut Neel/CNRS, Universite J. Fourier, CEA/INAC/SP2M, 17 rue des Martyrs, 38 054 Grenoble Cedex 9 (France); Attal-Tretout, B. [ONERA - Departement Mesures Physiques - DMPh, 27 Chemin de la Huniere, 91761 Palaiseau Cedex (France); Barjon, J. [GEMaC, Universite de Versailles St Quentin, CNRS Bellevue, 1 Place Aristide Briand, 92195 Meudon Cedex (France); Watanabe, K.; Taniguchi, T. [National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan); Kanaev, A. [Laboratoire des Sciences des Procedes et des Materiaux - LSPM, CNRS UPR 3407, Universite Paris 13, 93430 Villetaneuse (France)

    2011-06-15

    Near band gap photoluminescence (PL) of a hexagonal boron nitride single crystal has been studied at cryogenic temperatures with synchrotron radiation excitation. The PL signal is dominated by trapped-exciton optical transitions, while the photoluminescence excitation (PLE) spectra show features assigned to free excitons. Complementary photoconductivity and PLE measurements set the band gap transition energy to 6.4 eV and the Frenkel exciton binding energy larger than 380 meV. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Oxygen diffusion in [alpha]-Zr single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Hood, G.M. (Reactor Materials Research Branch, Chalk River Laboratories, Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)); Zou, H. (Reactor Materials Research Branch, Chalk River Laboratories, Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)); Herbert, S. (Reactor Materials Research Branch, Chalk River Laboratories, Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)); Schultz, R.J. (Reactor Materials Research Branch, Chalk River Laboratories, Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)); Nakajima, H. (Department of Materials Science and Technology, Iwate University, Morioka 020 (Japan)); Jackman, J.A. (Metals Science and Technology, CANMET, Booth St., Ottawa, Ontario (Canada))

    1994-06-01

    Oxygen diffusion coefficients, D, have been measured in [alpha]-Zr single crystals in directions both parallel and perpendicular to the c-axis. The measurements, made in the interval 610-870 K, show that diffusion anisotropy is weak and that D is little affected by specimen impurity content. The values determined here are in good agreement with the bulk of previous literature data for the same temperature interval but they are about ten times larger than corresponding values found in a very recent AES study. ((orig.))

  20. Diffusion of Ti in [alpha]-Zr single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Hood, G.M. (Reactor Materials Division Atomic Energy of Canada Ltd., Chalk River Laboratories, Chalk River, Ontario (Canada)); Zou, H. (Reactor Materials Division Atomic Energy of Canada Ltd., Chalk River Laboratories, Chalk River, Ontario (Canada)); Schultz, R.J. (Reactor Materials Division Atomic Energy of Canada Ltd., Chalk River Laboratories, Chalk River, Ontario (Canada)); Bromley, E.H.; Jackman, J.A. (CANMET, Metals Technology Laboratories, Ottawa, Ontario (Canada))

    1994-12-01

    Ti diffusion coefficients (D) have been measured in nominally pure [alpha]-Zr single crystals (773-1124 K) in directions both parallel (D[sub pa]) and perpendicular (D[sub pe], few data) to the c-axis: tracer techniques and secondary ion mass spectrometry were used to determine the diffusion profiles. The results show a temperature dependence which may be interpreted in terms of two regions of diffusion behaviour. Above 1035 K, region I, diffusion conforms to the expectations of intrinsic behaviour with normal Arrhenius law constants: Below 1035 K, region II, D's appear to be enhanced with respect to an extrapolation of region I behaviour. ((orig.))

  1. Depressurization amorphization of single-crystal boron carbide.

    Science.gov (United States)

    Yan, X Q; Tang, Z; Zhang, L; Guo, J J; Jin, C Q; Zhang, Y; Goto, T; McCauley, J W; Chen, M W

    2009-02-20

    We report depressurization amorphization of single-crystal boron carbide (B4C) investigated by in situ high-pressure Raman spectroscopy. It was found that localized amorphization of B4C takes place during unloading from high pressures, and nonhydrostatic stresses play a critical role in the high-pressure phase transition. First-principles molecular dynamics simulations reveal that the depressurization amorphization results from pressure-induced irreversible bending of C-B-C atomic chains cross-linking 12 atom icosahedra at the rhombohedral vertices.

  2. Growth of bulk gadolinium pyrosilicate single crystals for scintillators

    Science.gov (United States)

    Gerasymov, I.; Sidletskiy, O.; Neicheva, S.; Grinyov, B.; Baumer, V.; Galenin, E.; Katrunov, K.; Tkachenko, S.; Voloshina, O.; Zhukov, A.

    2011-03-01

    Ce, Pr, and La-doped gadolinium pyrosilicate Gd2Si2O7 (GPS) single crystals were grown by the Czochralski and Top Seeded Solution Growth (TSSG) techniques for the first time. Formation conditions of different pyrosilicate phases were determined. X-ray luminescence integral intensity of Ce-doped GPS is about one order of magnitude higher in comparison with gadolinium oxyorthosilicate Gd2SiO5:Ce (GSO:Ce). All samples demonstrate temperature stability of luminescence yield up to 400 K.

  3. Nonlinear microwave switching response of BSCCO single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, T.; Sridhar, S. [Northeastern Univ., Boston, MA (United States). Dept. of Physics; Willemsen, B.A. [Northeastern Univ., Boston, MA (United States). Dept. of Physics]|[Rome Lab., Hanscom AFB, MA (United States); Li, Qiang [Brookhaven National Lab., Upton, NY (United States); Gu, G.D.; Koshizuka, N. [Superconductivity Research Lab., Tokyo (Japan)

    1996-06-01

    Measurements of the surface impedance in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} single crystal with microwave currents flowing along the {cflx c} axis show clear evidence of a step-like nonlinearity. The surface resistance switches between apparently quantized levels for microwave field strength changes < 1 mG. This nonlinear response can arise from the presence of intrinsic Josephson junctions along the {cflx c} axis of these samples driven by the microwave current.

  4. Aluminum-rich mesoporous MFI - type zeolite single crystals

    DEFF Research Database (Denmark)

    Kustova, Marina; Kustov, Arkadii; Christensen, Christina Hviid

    2005-01-01

    Zeolitcs are crystalline materials, which are widely used as solid acid catalysts and supports in many industrial processes. Recently, mesoporous MFI-type zeolite single crystals were synthesized by use of carbon particles as a mesopore template and sodium aluminate as the aluminum Source...... are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), ammonia temperature programmed desorption (NH3-TPD), and N-2 adsorption measurements. The obtained zeolites combine the high crystallinity and the characteristic micropores of zeolites with an intracrystalline mesopore system...

  5. The sublimation kinetics of GeSe single crystals

    Science.gov (United States)

    Irene, E. A.; Wiedemeier, H.

    1975-01-01

    The sublimation kinetics of (001) oriented GeSe single crystal platelets was studied by high-temperature mass spectroscopy, quantitative vacuum microbalance techniques, and hot stage optical microscopy. For a mean experimental temperature of 563 K, the activation enthalpy and entropy are found to equal 32.3 kcal/mole and 19.1 eu, respectively. The vaporization coefficient is less than unity for the range of test temperatures, and decreases with increasing temperature. The combined experimental data are correlated by means of a multistep surface adsorption mechanism.

  6. EPR studies of gamma-irradiated taurine single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Bulut, A. E-mail: abulut@samsun.omu.edu.tr; Karabulut, B.; Tapramaz, R.; Koeksal, F

    2000-04-01

    An EPR study of gamma-irradiated taurine [C{sub 2}H{sub 7}NO{sub 3}S] single crystal was carried out at room temperature. The EPR spectra were recorded in the three at mutually perpendicular planes. There are two magnetically distinct sites in monoclinic lattice. The principle values of g and hyperfine constants for both sites were calculated. The results have indicated the presence of {sup 32}SO{sup -}{sub 2} and {sup 33}SO{sup -}{sub 2} radicals. The hyperfine values of {sup 33}SO{sup -}{sub 2} radical were used to obtain O-S-O bond angle for both sites.

  7. Single Molecule Studies on Dynamics in Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Daniela Täuber

    2013-09-01

    Full Text Available Single molecule (SM methods are able to resolve structure related dynamics of guest molecules in liquid crystals (LC. Highly diluted small dye molecules on the one hand explore structure formation and LC dynamics, on the other hand they report about a distortion caused by the guest molecules. The anisotropic structure of LC materials is used to retrieve specific conformation related properties of larger guest molecules like conjugated polymers. This in particular sheds light on organization mechanisms within biological cells, where large molecules are found in nematic LC surroundings. This review gives a short overview related to the application of highly sensitive SM detection schemes in LC.

  8. Single crystal piezoelectric composites for advanced NDT ultrasound

    Science.gov (United States)

    Jiang, Xiaoning; Snook, Kevin; Hackenberger, Wesley S.; Geng, Xuecang

    2007-04-01

    In this paper, the design, fabrication and characterization of PMN-PT single crystal/epoxy composites are reported for NDT ultrasound transducers. Specifically, 1-3 PMN-PT/epoxy composites with center frequencies of 5 MHz - 40 MHz were designed and fabricated using either the dice-and-fill method or a photolithography based micromachining process. The measured electromechanical coefficients for composites with frequency of 5 MHz - 15 MHz were about 0.78-0.83, and the coupling coefficients for composites with frequencies of 25 MHz- 40 MHz were about 0.71-0.72. The dielectric loss remains low (advanced NDT ultrasound applications.

  9. 9R structure in drawn industrial single crystal copper wires

    Institute of Scientific and Technical Information of China (English)

    CHEN Jian; YAN Wen; FAN Xin-hui

    2009-01-01

    By using transmission electron microscopy, the microstructures of drawn industrial single crystal copper wires produced by Ohno Continuous Casting(OCC) process were analyzed. The results show that the typical microstructures in the wires mainly include extended planar dislocation boundaries, a small fraction of twins and some dislocation cells sharing boundaries parallel to drawn direction. Besides the typical microstructures, 9R structure configurations were observed in the wires. The formation of 9R polytypes may be caused by the coupled emission of Shockley dislocations from a boundary.

  10. Tensor tomography of stresses in cubic single crystals

    Directory of Open Access Journals (Sweden)

    Dmitry D. Karov

    2015-03-01

    Full Text Available The possibility of optical tomography applying to investigation of a two-dimensional and a three-dimensional stressed state in single cubic crystals has been studied. Stresses are determined within the framework of the Maxwell piezo-optic law (linear dependence of the permittivity tensor on stresses and weak optical anisotropy. It is shown that a complete reconstruction of stresses in a sample is impossible both by translucence it in the parallel planes system and by using of the elasticity theory equations. For overcoming these difficulties, it is offered to use a method of magnetophotoelasticity.

  11. Capillarity creates single-crystal calcite nanowires from amorphous calcium carbonate.

    Science.gov (United States)

    Kim, Yi-Yeoun; Hetherington, Nicola B J; Noel, Elizabeth H; Kröger, Roland; Charnock, John M; Christenson, Hugo K; Meldrum, Fiona C

    2011-12-23

    Single-crystal calcite nanowires are formed by crystallization of morphologically equivalent amorphous calcium carbonate (ACC) particles within the pores of track etch membranes. The polyaspartic acid stabilized ACC is drawn into the membrane pores by capillary action, and the single-crystal nature of the nanowires is attributed to the limited contact of the intramembrane ACC particle with the bulk solution. The reaction environment then supports transformation to a single-crystal product.

  12. ‘Ionic crystals’ consisting of trinuclear macrocations and polyoxometalate anions exhibiting single crystal to single crystal transformation: breathing of crystals

    Indian Academy of Sciences (India)

    T ARUMUGANATHAN; ASHA SIDDIKHA; SAMAR K DAS

    2017-08-01

    Ion pairing of trinuclear macrocation cluster (known as basic carboxylate), [M ₃ (μ ₃-O) (ClCH ₂COO) ₆ (H ₂O) ₃] ¹⁺ and a Keggin type polyoxometalate cluster anion [SiW ₁₂O₄₀] ⁴⁻ is stabilized with a number of crystal water molecules in composite type compounds [M ₃ (μ ₃-O)(ClCH ₂COO) ₆ (H ₂O) ₃] ₄[SiW ₁₂O₄₀] ·xH ₂O · 2ClCH ₂COOH [M = Fe ³⁺, x = 18(1); M = Cr ³⁺x = 14(2)]. When the crystals of 1 are heated at 85◦C and 135◦C for 3.5 hours in an open atmospheric condition, it goes to [Fe ₃ (μ ₃-O)(ClCH ₂COO) ₆ (H ₂O) ₃] ₄ [SiW ₁₂O₄₀] ·10H ₂O ·2ClCH ₂COOH (dehydrated 1-85o ≡ 1'), and [Fe ₃ (μ ₃-O) (ClCH ₂COO) ₆ (H ₂O) ₃] ₄ [SiW ₁₂O₄₀] · 8H ₂O · 2ClCH ₂COOH (dehydrated 1-135o ≡ 1'') respectively with the loss of considerable amount of lattice water molecules retaining their single crystallinity. On the other hand, the single crystals of compound 2, upon heating at 85◦C or 135◦C for 3.5 hours, undergo ‘crystal-to-crystal transformation’ to the single crystals of [Cr ₃ (μ ₃-O)(ClCH ₂COO) ₆ (H ₂O) ₃] ₄ [SiW₁₂O₄₀]·8H₂O·2ClCH ₂COOH (dehydrated 2 ≡ 2'). Crystal structure analyses show that the parent compounds 1 and 2 undergo molecular rearrangement (molecular motion in the solid state) in respective dehydrated compounds. Remarkably, these dehydrated crystals (1', 1'' and 2'), upon exposure to water vapor at an ambient condition, regenerate the crystals of parent compounds 1 and 2, respectively

  13. Single nanoparticle detection using photonic crystal enhanced microscopy.

    Science.gov (United States)

    Zhuo, Yue; Hu, Huan; Chen, Weili; Lu, Meng; Tian, Limei; Yu, Hojeong; Long, Kenneth D; Chow, Edmond; King, William P; Singamaneni, Srikanth; Cunningham, Brian T

    2014-03-07

    We demonstrate a label-free biosensor imaging approach that utilizes a photonic crystal (PC) surface to detect surface attachment of individual dielectric and metal nanoparticles through measurement of localized shifts in the resonant wavelength and resonant reflection magnitude from the PC. Using a microscopy-based approach to scan the PC resonant reflection properties with 0.6 μm spatial resolution, we show that metal nanoparticles attached to the biosensor surface with strong absorption at the resonant wavelength induce a highly localized reduction in reflection efficiency and are able to be detected by modulation of the resonant wavelength. Experimental demonstrations of single-nanoparticle imaging are supported by finite-difference time-domain computer simulations. The ability to image surface-adsorption of individual nanoparticles offers a route to single molecule biosensing, in which the particles can be functionalized with specific recognition molecules and utilized as tags.

  14. Q-switching with single crystal photo-elastic modulators

    Science.gov (United States)

    Bammer, F.; Petkovsek, R.

    2011-02-01

    An overview is given about experiments with a new method for Q-switching lasers at a constant pulse repetition frequency. It uses inside the laser resonator a Single Crystal Photo-Elastic Modulator (SCPEM). This consists of one piezo-electric crystal electrically excited on a mechanical resonance frequency. In resonance mechanical stresses are induced that lead via the photo-elastic effect to a strongly modulated birefringence. Polarized light going through such an oscillating crystal will experience a significant modulation of its polarization and of transmission through a polarizer. Suitable materials should not be optically active, as it is for example the case for SiO2, and should allow the excitation of a longitudinal oscillation with an electric field perpendicular to the travelling direction of the light. Crystals of the group 3m, like LiTaO3 and LiNbO3, proved to be ideally suited for SCPEMS for the NIR- and VIS-region. For the infrared GaAs can be used. We demonstrated SCPEM-Q-switching for a Nd:YAG-fiber, a Nd:YVO4-slab- and a Nd:YAG-rod-laser with typical pulse repetition rates of 100-200kHz, pulse enhancement factors of 100 and pulse durations {1/100 of the period time. Typically the average power during pulsed operation is nearly the same as the cw-power, when the modulator is switched off. The most stable results were achieved up to now with the Nd:YVO4-slab-laser at 10W average power, 1.1 kW peak power, 127 kHz pulse repetition rate, and 70ns pulse durations.

  15. Growth and properties of Lithium Salicylate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Zaitseva, N; Newby, J; Hull, G; Saw, C; Carman, L; Cherepy, N; Payne, S

    2009-02-13

    An attractive feature of {sup 6}Li containing fluorescence materials that determines their potential application in radiation detection is the capture reaction with slow ({approx}< 100 keV) neutrons: {sup 6}Li + n = {sup 4}He + {sup 3}H + 4.8MeV. The use of {sup 6}Li-salicylate (LiSal, LiC{sub 6}H{sub 5}O{sub 3}) for thermal neutron detection was previously studied in liquid and polycrystalline scintillators. The studies showed that both liquid and polycrystalline LiSal scintillators could be utilized in pulse shape discrimination (PSD) techniques that enable separation of neutrons from the background gamma radiation. However, it was found that the efficiency of neutron detection using LiSal in liquid solutions was severely limited by its low solubility in commonly used organic solvents like, for example, toluene or xylene. Better results were obtained with neutron detectors containing the compound in its crystalline form, such as pressed pellets, or microscopic-scale (7-14 micron) crystals dispersed in various media. The expectation drown from these studies was that further improvement of pulse height, PSD, and efficiency characteristics could be reached with larger and more transparent LiSal crystals, growth of which has not been reported so far. In this paper, we present the first results on growth and characterization of relatively large, a cm-scale size, single crystals of LiSal with good optical quality. The crystals were grown both from aqueous and anhydrous (methanol) media, mainly for neutron detection studies. However, the results on growth and structural characterization may be interesting for other fields where LiSal, together with other alkali metal salicylates, is used for biological, medical, and chemical (as catalyst) applications.

  16. The crystal structure and twinning of neodymium gallium perovskite single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ubizskii, S.B.; Vasylechko, L.O.; Savytskii, D.I.; Matkovskii, A.O.; Syvorotka, I.M. [Res. Production Amalgamation Carat, L' viv (Ukraine)

    1994-10-01

    By means of X-ray structure analysis, the crystal structure of neodymium gallium perovskite (NGP) single crystals (NdGaO{sub 3}) being used as a substrate for HTSC film epitaxy has been refined and the position of atoms has been determined. The possibility of YBa{sub 2}Cu{sub 3}O{sub 7-x} film epitaxy on the plane (110) of NGP crystal as well as its advantages and pitfalls are analysed from structural data. The twinning types in the NGP crystal were established. The twinning structure of NGP substrates is found to be stable up to a temperature of 1173 K, as differentiated from the LaGaO{sub 3} and LaAlO{sub 3} substrates. It is intimated that the twinning in the NGP substrates oriented as (001) can result in creation of 90 degrees twin bonds in a film, and in the case of (110)-oriented plates it is possible to ignore the twinning presence in substrate completely. (author)

  17. Aging and memory effect in magnetoelectric gallium ferrite single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Vijay; Mukherjee, Somdutta [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Mitra, Chiranjib [Department of Physics, Indian Institute of Science Education and Research, Kolkata 741252 (India); Garg, Ashish [Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Gupta, Rajeev, E-mail: guptaraj@iitk.ac.in [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

    2015-02-01

    Here, we present a time and temperature dependent magnetization study to understand the spin dynamics in flux grown single crystals of gallium ferrite (GaFeO{sub 3}), a known magnetoelectric, ferroelectric and ferrimagnet. Results of the magnetic measurements conducted in the field-cooled (FC) and zero-field-cooled (ZFC) protocols in the heating and cooling cycles were reminiscent of a “memory” effect. Subsequent time dependent magnetic relaxation measurements carried out in ZFC mode at 30 K with an intermittent cooling to 20 K in the presence of a small field show that the magnetization in the final wait period tends to follow its initial state which was present before the cooling break taken at 20 K. These observations provide an unambiguous evidence of single crystal gallium ferrite having a spin glass like phase. - Highlights: • Gallium ferrite a room temperature magnetoelectric and ferrimagnetic material. • Spin‐glass like phase at low temperatures below ∼200 K. • Observation of memory and aging effects in GFO.

  18. Large single-crystal diamond substrates for ionizing radiation detection

    Energy Technology Data Exchange (ETDEWEB)

    Girolami, Marco; Bellucci, Alessandro; Calvani, Paolo; Trucchi, Daniele M. [Istituto di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche (CNR), Sede Secondaria di Montelibretti, Monterotondo Stazione, Roma (Italy)

    2016-10-15

    The need for large active volume detectors for ionizing radiations and particles, with both large area and thickness, is becoming more and more compelling in a wide range of applications, spanning from X-ray dosimetry to neutron spectroscopy. Recently, 8.0 x 8.0 mm{sup 2} wide and 1.2 mm thick single-crystal diamond plates have been put on the market, representing a first step to the fabrication of large area monolithic diamond detectors with optimized charge transport properties, obtainable up to now only with smaller samples. The more-than-double thickness, if compared to standard plates (typically 500 μm thick), demonstrated to be effective in improving the detector response to highly penetrating ionizing radiations, such as γ-rays. Here we report on the first measurements performed on large active volume single-crystal diamond plates, both in the dark and under irradiation with optical wavelengths (190-1100 nm), X-rays, and radioactive γ-emitting sources ({sup 57}Co and {sup 22}Na). (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Ultrafast dynamic response of single crystal β-HMX

    Science.gov (United States)

    Zaug, Joseph M.; Armstrong, Michael R.; Crowhurst, Jonathan C.; Radousky, Harry B.; Ferranti, Louis; Swan, Raymond; Gross, Rick; Teslich, Nick E.; Wall, Mark A.; Austin, Ryan A.; Fried, Laurence E.

    2017-01-01

    We report results from ultrafast compression experiments conducted on β-HMX single crystals. Results consist of nominally 12 picosecond time-resolved wave profile data, (ultrafast time domain interferometry -TDI measurements), that were analyzed to determine high-velocity wave speeds as a function of piston velocity. TDI results are used to validate calculations of anisotropic stress-strain behavior of shocked loaded energetic materials. Our previous results derived using a 350 ps duration compression drive revealed anisotropic elastic wave response in single crystal β-HMX from (110) and (010) impact planes. Here we present results using a 1.05 ns duration compression drive with a 950 ps interferometry window to extend knowledge of the anisotropic dynamic response of β-HMX within eight microns of the initial impact plane. We observe two distinct wave profiles from (010) and three wave profiles from (010) impact planes. The (110) impact plane wave speeds typically exceed (010) impact plane wave speeds at the same piston velocities. The development of multiple hydrodynamic wave profiles begins at 20 GPa for the (110) impact plane and 28 GPa for the (10) impact plane. We compare our ultrafast TDI results with previous gun and plate impact results on β-HMX and PBX9501.

  20. Stress topology within silicon single-crystal cantilever beam

    Directory of Open Access Journals (Sweden)

    Alexander P. Kuzmenko

    2015-06-01

    Full Text Available Flexural elastic deformations of single-crystal silicon have been studied using microspectral Raman scattering. Results are reported on nano-scaled sign-changing shifts of the main peak of the microspectral Raman scattering within the single-crystal silicon cantilever beam during exposure to flexural stress. The maximum value of Raman shift characteristic of the 518 cm−1 silicon peak at which elasticity still remains has been found to be 8 cm−1 which corresponds to an applied deformation of 4 GPa. We report three-dimensional maps of the distribution of internal stresses at different levels of deformation up to irreversible changes and brittle fracture of the samples that clearly show compression and tension areas and an undeformed area. A qualitative explanation of the increase in the strength of the cantilever beam due to its small thickness (2 μm has been provided that agrees with the predictions of real-world physical parameters obtained in SolidWorks software environment with the SimulationXpress module. We have defined the relative strain of the beam surface which was 2% and received a confirmation of changes in the silicon lattice parameter from 0.54307 nm to 0.53195 nm by the BFGS algorithm.

  1. The refractive index of zinc oxide microwire single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Czekalla, Christian; Kuehne, Philipp; Sturm, Chris; Schmidt-Grund, Ruediger; Grundmann, Marius [Universitaet Leipzig (Germany). Fakultaet fuer Physik und Geowissenschaften, Institut fuer Experimentelle Physik II

    2010-07-01

    Among a large number of applications, zinc oxide (ZnO) single crystals (bulk and micro- and nanowires) are expected to form important building blocks for future optoelectronic devices like light emitting and laser diodes. Optical resonances from ZnO structures have been observed by a number of groups in the past years. In most of the publications, modeling of the mode structure, especially in the near bandgap spectral region, is difficult because the energy dependent refractive index n(E) is typically not known. Additionally, in case of the self assembled micro- and nanowires, the structures are too small to perform spectroscopic ellipsometry to determine n(E). We compare n(E) obtained from (a) spectroscopic ellipsometry measurements of ZnO bulk single crystals and (b) spatially resolved photoluminescence measurements of ZnO microwires employing a plane wave whispering gallery mode model for the observed resonances. We discuss the differences between the results obtained from the two methods and their mutual impact, leading to a highly precise determination of n(E) in an energy range between 1.80 eV and 3.25 eV and for temperatures between 10 K and 295 K.

  2. Single Crystal Diamond Needle as Point Electron Source

    Science.gov (United States)

    Kleshch, Victor I.; Purcell, Stephen T.; Obraztsov, Alexander N.

    2016-10-01

    Diamond has been considered to be one of the most attractive materials for cold-cathode applications during past two decades. However, its real application is hampered by the necessity to provide appropriate amount and transport of electrons to emitter surface which is usually achieved by using nanometer size or highly defective crystallites having much lower physical characteristics than the ideal diamond. Here, for the first time the use of single crystal diamond emitter with high aspect ratio as a point electron source is reported. Single crystal diamond needles were obtained by selective oxidation of polycrystalline diamond films produced by plasma enhanced chemical vapor deposition. Field emission currents and total electron energy distributions were measured for individual diamond needles as functions of extraction voltage and temperature. The needles demonstrate current saturation phenomenon and sensitivity of emission to temperature. The analysis of the voltage drops measured via electron energy analyzer shows that the conduction is provided by the surface of the diamond needles and is governed by Poole-Frenkel transport mechanism with characteristic trap energy of 0.2-0.3 eV. The temperature-sensitive FE characteristics of the diamond needles are of great interest for production of the point electron beam sources and sensors for vacuum electronics.

  3. 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.

  4. Size effects on void growth in single crystals with distributed voids

    DEFF Research Database (Denmark)

    Borg, Ulrik; Niordson, Christian Frithiof; Kysar, J.W.

    2008-01-01

    The effect of void size on void growth in single crystals with uniformly distributed cylindrical voids is studied numerically using a finite deformation strain gradient crystal plasticity theory with an intrinsic length parameter. A plane strain cell model is analyzed for a single crystal...

  5. Crystal Growth and Properties of Co2+ doped Y3Sc2Ga3O12 Single Crystal

    Institute of Scientific and Technical Information of China (English)

    Guo Shiyi; Yuan Duorong; Shi Xuzhong; Cheng Xiufeng; Zhang Xiqing; Yu Fapeng

    2007-01-01

    Single crystal of cobalt (Co)-doped Y3Sc2Ga3O12 (YSGG) with the dimensions up to φ20×40mm3 and undoped YSGG crystal with the dimensions up to φ28×60mm3 have been grown using the Czochralski technique. The structure of the crystal was characterized by the X-ray powder diffraction (XRPD) method. The absorbance spectra of the crystal shows that it has strong absorption bands at 606 and 1540nm. The results indicate that the crystal Y3Sc2Ga3O12 may be a kind of good Q-switch material.

  6. Growth and Characterization of Pure and Doped L-Alanine Tartrate Single Crystals

    Directory of Open Access Journals (Sweden)

    K. Rajesh

    2013-01-01

    Full Text Available Single crystals of pure and Lanthanum doped L-Alanine Tartrate were grown by slow evaporation method. The cell parameters were determined using single crystal X-ray diffraction method. To improve the physical properties of the LAT crystal, Lanthanum dopant was added by 2 mol%. ICP studies confirm the presence of Lanthanum in the grown LAT crystal. Transparency range of the crystal was determined using UV-VIS-NIR spectrophotometer. The functional groups of pure and doped LAT crystals were analyzed by FT-IR spectroscopy. Using Vickers microhardness tester, mechanical strength of the material was found. Dielectric studies of pure and doped LAT single crystals were carried out. The doped LAT crystal is found to have efficiency higher than that of pure LAT crystal.

  7. A preliminary review of organic materials single crystal growth by the Czochralski technique

    Science.gov (United States)

    Penn, B. G.; Shields, A. W.; Frazier, D. O.

    1988-01-01

    The growth of single crystals of organic compounds by the Czochralski method is reviewed. From the literature it is found that single crystals of benzil, a nonlinear optical material with a d sub 11 value of 11.2 + or - 1.5 x d sub 11 value of alpha quartz, has fewer dislocations than generally contained in Bridgman crystals. More perfect crystals were grown by repeated Czochralski growth. This consists of etching away the defect-containing portion of a Czochralski grown crystal and using it as a seed for further growth. Other compounds used to grow single crystals are benzophenone, 12-tricosanone (laurone), and salol. The physical properties, growth apparatus, and processing conditions presented in the literature are discussed. Moreover, some of the possible advantages of growing single crystals of organic compounds in microgravity to obtain more perfect crystals than on Earth are reviewed.

  8. Single Crystal DMs for Space-Based Observatories

    Science.gov (United States)

    Bierden, Paul

    We propose to demonstrate the feasibility of a new manufacturing process for large aperture, high-actuator count microelectromechanical deformable mirrors (MEMS-DMs). These DMs are designed to fill a critical technology gap in NASA s plan for high- contrast space-based exoplanet observatories. We will manufacture a prototype DM with a continuous mirror facesheet, having an active aperture of 50mm diameter, supported by 2040 electrostatic actuators (50 across the diameter of the active aperture), spaced at a pitch of 1mm. The DM will be manufactured using silicon microfabrication tools. The strategic motivation for the proposed project is to advance MEMS DMs as an enabling technology in NASA s rapidly emerging program for extrasolar planet exploration. That goal is supported by an Astro2010 white paper on Technologies for Direct Optical Imaging of Exoplanets, which concluded that DMs are a critical component for all proposed internal coronagraph instrument concepts. That white paper pointed to great strides made by DM developers in the past decade, and acknowledged the components made by Boston Micromachines Corporation to be the most notable MEMS-based technology option. The principal manufacturing innovation in this project will be assembly of the DM through fusion bonding of three separate single crystal silicon wafers comprising the device s substrate, actuator array, and facesheet. The most significant challenge of this project will be to develop processes that allow reliable fusion bonds between multiple compliant silicon layers while yielding an optically flat surface and a robust electromechanical system. The compliance of the DM, which is required for its electromechanical function, will make it challenging to achieve the intimate, planar contact that is generally needed for success in fusion bonding. The manufacturing approach will use photolithography and reactive ion etching to pattern structural layers. Three wafer-scale devices will be patterned and

  9. Crystal growth, structural, thermal and mechanical behavior of L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) single crystals

    Science.gov (United States)

    Mahadevan, M.; Ramachandran, K.; Anandan, P.; Arivanandhan, M.; Bhagavannarayana, G.; Hayakawa, Y.

    2014-12-01

    Single crystals of L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) have been grown successfully from the solution of L-arginine and 4-nitrophenol. Slow evaporation of solvent technique was adopted to grow the bulk single crystals. Single crystal X-ray diffraction analysis confirms the grown crystal has monoclinic crystal system with space group of P21. Powder X-ray diffraction analysis shows the good crystalline nature. The crystalline perfection of the grown single crystals was analyzed by HRXRD by employing a multicrystal X-ray diffractometer. The functional groups were identified from proton NMR spectroscopic analysis. Linear and nonlinear optical properties were determined by UV-Vis spectrophotometer and Kurtz powder technique respectively. It is found that the grown crystal has no absorption in the green wavelength region and the SHG efficiency was found to be 2.66 times that of the standard KDP. The Thermal stability of the crystal was found by obtaining TG/DTA curve. The mechanical behavior of the grown crystal has been studied by Vicker's microhardness method.

  10. Ignition and growth modeling of detonation reaction zone experiments on single crystals of PETN and HMX

    Science.gov (United States)

    White, Bradley W.; Tarver, Craig M.

    2017-01-01

    It has long been known that detonating single crystals of solid explosives have much larger failure diameters than those of heterogeneous charges of the same explosive pressed or cast to 98 - 99% theoretical maximum density (TMD). In 1957, Holland et al. demonstrated that PETN single crystals have failure diameters of about 8 mm, whereas heterogeneous PETN charges have failure diameters of less than 0.5 mm. Recently, Fedorov et al. quantitatively determined nanosecond time resolved detonation reaction zone profiles of single crystals of PETN and HMX by measuring the interface particle velocity histories of the detonating crystals and LiF windows using a PDV system. The measured reaction zone time durations for PETN and HMX single crystal detonations were approximately 100 and 260 nanoseconds, respectively. These experiments provided the necessary data to develop Ignition and Growth (I&G) reactive flow model parameters for the single crystal detonation reaction zones. Using these parameters, the calculated unconfined failure diameter of a PETN single crystal was 7.5 +/- 0.5 mm, close to the 8 mm experimental value. The calculated failure diameter of an unconfined HMX single crystal was 15 +/- 1 mm. The unconfined failure diameter of an HMX single crystal has not yet been determined precisely, but Fedorov et al. detonated 14 mm diameter crystals confined by detonating a HMX-based plastic bonded explosive (PBX) without initially overdriving the HMX crystals.

  11. Growth of ZnO Single Crystal by Chemical Vapor Transport Method

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    ZnO crystals were grown by CVT method in closed quartz tube under seeded condition. Carbon was used as a transport agent to enhance the chemical transport of ZnO in the growth process. ZnO single crystals were grown by using GaN/sapphire and GaN/Si wafer as seeds. The property and crystal quality of the ZnO single crystals was studied by photoluminescence spectroscopy and X-ray diffraction technique.

  12. Floating Zone Growth and Thermionic Emission Property of Single Crystal CeB6

    Institute of Scientific and Technical Information of China (English)

    BAO Li-Hong; ZHANG Jiu-Xing; ZHOU Shen-Lin; ZHANG Ning; XU Hong

    2011-01-01

    @@ Large-sized and high-quality cerium hexaboride(CeB6) single crystals are successfully grown yb the optical floating zone method.The structure, chemical composition and thermionic emission properties of the crystal are characterized by x-ray diffraction, x-ray fluorescence and emission measurements, respectively.Based on the observation of single crystal diffraction, the relative density of feed rods has a great effect on the quality of the grown crystal.The thermionic emission measurement results show that the emission current density of the single crystal is 47.1 A/cm2 at 1873K with an applied voltage of 1 kV,which is about two times larger than the value for polycrystalline samples.The single crystal possesses excellent emission current stability.Therefore, it is expected that CeBs single crystal is a very promising material for thermionic cathode applications.

  13. Twin nucleation and migration in FeCr single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Patriarca, L. [Politecnico di Milano, Department of Mechanical Engineering, Via La Masa 34, I-20156 Milano (Italy); Abuzaid, Wael [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green St., Urbana, IL 61801 (United States); Sehitoglu, Huseyin, E-mail: huseyin@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green St., Urbana, IL 61801 (United States); Maier, Hans J. [Lehrstuhl fuer Werkstoffkunde (Materials Science), University of Paderborn, 33095 Paderborn (Germany); Chumlyakov, Y. [Physics of Plasticity and Strength of Materials Laboratory, Siberian Physical and Technical Institute, 634050 Tomsk (Russian Federation)

    2013-01-15

    Tension and compression experiments were conducted on body-centered cubic Fe -47.8 at pct. Cr single crystals. The critical resolved shear stress (CRSS) magnitudes for slip nucleation, twin nucleation and twin migration were established. We show that the nucleation of slip occurs at a CRSS of about 88 MPa, while twinning nucleates at a CRSS of about 191 MPa with an associated load drop. Following twin nucleation, twin migration proceeds at a CRSS that is lower than the initiation stress ( Almost-Equal-To 114-153 MPa). The experimental results of the nucleation stresses indicate that the Schmid law holds to a first approximation for the slip and twin nucleation cases, but to a lesser extent for twin migration particularly when considerable slip strains preceded twinning. The CRSSs were determined experimentally using digital image correlation (DIC) in conjunction with electron back scattering diffraction (EBSD). The DIC measurements enabled pinpointing the precise stress on the stress-strain curves where twins or slip were activated. The crystal orientations were obtained using EBSD and used to determine the activated twin and slip systems through trace analysis. - Highlights: Black-Right-Pointing-Pointer Digital image correlation allows to capture slip/twin initiation for bcc FeCr. Black-Right-Pointing-Pointer Crystal orientations from EBSD allow slip/twin system indexing. Black-Right-Pointing-Pointer Nucleation of slip always precedes twinning. Black-Right-Pointing-Pointer Twin growth is sustained with a lower stress than required for nucleation. Black-Right-Pointing-Pointer Twin-slip interactions provide high hardening at the onset of plasticity.

  14. Growth of Bi-2212 single crystals by a horizontal Bridgman method using different oxygen pressure

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, M.; Makino, T.; Nakabayashi, T. [Department of Electrical and Electronic Engineering, Tottori University, Koyama-Minami, Tottori 680-8552 (Japan); Tanaka, H. [Yonago National College of Technology, 4448 Hikona Yonago, Tottori 683-8502 (Japan); Kinoshita, K., E-mail: kinoshita@ele.tottori-u.ac.j [Department of Electrical and Electronic Engineering, Tottori University, Koyama-Minami, Tottori 680-8552 (Japan); Kishida, S. [Department of Electrical and Electronic Engineering, Tottori University, Koyama-Minami, Tottori 680-8552 (Japan)

    2009-10-15

    We compared the crystallinity of the Bi-2212 single crystals grown by the horizontal Bridgman (HB) method with those grown by the vertical Bridgman (VB) method in terms of resistivity, rho. It was clarified that crystals far inside the ingot grown by HB method showed the equivalent crystallinity to crystals grown by VB method, whereas crystals near the surface of the ingot grown by HB method showed the similar crystallinity to crystals grown by TSFZ method, which is sensitive to the growth atmosphere.

  15. Tb-Dy-Fe Single Crystal and Magnetostrictive Actuator Using These Materials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Magnetostrictive actuators normally use twin-crystal magnetostrictive materials as driving unit. Because the crystal and twin-crystal plane hinder the movement of the domain wall, its displacement output of low magnetic strength is rather small. Using Tb-Dy-Fe single crystal technique can effectively solve the problems brought by pollution and twin crystals, and produce high-quality Tb-Dy-Fe single crystal materials. The paper will introduce the technique of using these materials to produce magnetostrictive actuators that possess high sensitivity and resolution and use pulse feeding.

  16. Growth and Characterization of Pure and Doped L-Alanine Tartrate Single Crystals

    OpenAIRE

    K. Rajesh; B. Milton Boaz; P. Praveen Kumar

    2013-01-01

    Single crystals of pure and Lanthanum doped L-Alanine Tartrate were grown by slow evaporation method. The cell parameters were determined using single crystal X-ray diffraction method. To improve the physical properties of the LAT crystal, Lanthanum dopant was added by 2 mol%. ICP studies confirm the presence of Lanthanum in the grown LAT crystal. Transparency range of the crystal was determined using UV-VIS-NIR spectrophotometer. The functional groups of pure and doped LAT crystals were a...

  17. Studies on synthesis, growth, structural, optical properties of organic 8-hydroxyquinolinium succinate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Thirumurugan, R., E-mail: singlecrystalxrd@gmail.com; Anitha, K., E-mail: singlecrystalxrd@gmail.com [School of Physics, Madurai Kamaraj University, Madurai-625021 (India)

    2014-04-24

    8-hydroxyquinolinium succinate (8HQSU), an organic material has been synthesized and single crystals were grown by employing the technique of slow evaporation. The structure of the grown crystal was elucidated by using single crystal X-ray diffraction analysis. 8HQSU crystal belongs to the monoclinic crystallographic system with non-centro symmetric space group of P2{sub 1}. FT-IR spectral investigation has been carried out to identify the various functional groups present in the grown crystal. UV–vis spectral studies reveal that 8HQSU crystals are transparent in the entire visible region and the cut-off wavelength has been found to be 220nm.

  18. Solidification microstructures in single-crystal stainless steel melt pools

    Energy Technology Data Exchange (ETDEWEB)

    Sipf, J.B.; Boatner, L.A.; David, S.A.

    1994-03-01

    Development of microstructure of stationary melt pools of oriented stainless steel single crystals (70%Fe-15%Ni-15%Cr was analyzed. Stationary melt pools were formed by electron-beam and gas-tungsten-arc heating on (001), (011), and (111) oriented planes of the austenitic, fcc-alloy crystals. Characterization and analysis of resulting microstructure was carried out for each crystallographic plane and welding method. Results showed that crystallography which favors ``easy growth`` along the <100> family of directions is a controlling factor in the microstructural formation along with the melt-pool shape. The microstructure was found to depend on the melting method, since each method forms a unique melt-pool shape. These results are used in making a three-dimensional reconstruction of the microstructure for each plane and melting method employed. This investigation also suggests avenues for future research into the microstructural properties of electron-beam welds as well as providing an experimental basis for mathematical models for the prediction of solidification microstructures.

  19. Scintillation properties of CsI:In single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gridin, S., E-mail: gridin.sergey@gmail.com [Institute for Scintillation Materials, 61001 Kharkov (Ukraine); Institut Lumière Matière, Lyon, 69622 Villeurbanne Cedex (France); Belsky, A. [Institut Lumière Matière, Lyon, 69622 Villeurbanne Cedex (France); Moszynski, M.; Syntfeld-Kazuch, A. [National Centre for Nuclear Research, Soltana 7, 05-400 Otwock-Swierk (Poland); Shiran, N.; Gektin, A. [Institute for Scintillation Materials, 61001 Kharkov (Ukraine)

    2014-10-11

    Scintillation properties of CsI:In single crystals have been investigated. Scintillation yield of CsI:In measured with the 24 μs integration time is around 27,000 ph/MeV, reaching the saturation at 0.005 mol% of the activator. However, luminescence yield of CsI:In is close to CsI:Tl scintillation crystals, which is around 60,000 ph/MeV. This difference is explained by the presence of an ultra-long afterglow in CsI:In scintillation pulse. Thermoluminescence studies revealed a stable trap around 240 K that is supposed to be related to millisecond decay components. The best measured energy resolution of (8.5±0.3)% was achieved at 24 μs peaking time for a CsI sample doped with 0.01 mol% of In. Temperature stability of CsI:In radioluminescence intensity was found to be remarkably high. Its X-ray luminescence yield remains stable up to 600 K, whereafter thermal quenching occurs. The latter property gives CsI:In a potential to be used in well logging applications.

  20. Ion implantation of CdTe single crystals

    Directory of Open Access Journals (Sweden)

    Wiecek Tomasz

    2017-01-01

    Full Text Available Ion implantation is a technique which is widely used in industry for unique modification of metal surface for medical applications. In semiconductor silicon technology ion implantation is also widely used for thin layer electronic or optoelectronic devices production. For other semiconductor materials this technique is still at an early stage. In this paper based on literature data we present the main features of the implantation of CdTe single crystals as well as some of the major problems which are likely to occur when dealing with them. The most unexpected feature is the high resistance of these crystals against the amorphization caused by ion implantation even at high doses (1017 1/cm2. The second property is the disposal of defects much deeper in the sample then it follows from the modeling calculations. The outline of principles of the ion implantation is included in the paper. The data based on RBS measurements and modeling results obtained by using SRIM software were taken into account.

  1. From Protein Structure to Function via Single Crystal Optical Spectroscopy

    Directory of Open Access Journals (Sweden)

    Luca eRonda

    2015-04-01

    Full Text Available The more than 100.000 protein structures determined by X-ray crystallography provide a wealth of information for the characterization of biological processes at the molecular level. However, several crystallographic artifacts, including conformational selection, crystallization conditions and radiation damages, may affect the quality and the interpretation of the electron density map, thus limiting the relevance of structure determinations. Moreover, for most of these structures no functional data have been obtained in the crystalline state, thus posing serious questions on their validity in the inference for protein mechanisms. In order to solve these issues, spectroscopic methods have been applied for the determination of equilibrium and kinetic properties of proteins in the crystalline state. These methods are UV-vis spectrophotometry, spectrofluorimetry, IR, EPR, Raman and resonance Raman spectroscopy. Some of these approaches have been implemented with on-line instruments at X-ray synchrotron beamlines. Here, we provide an overview of investigations predominantly carried out in our laboratory by single crystal polarized absorption UV-vis microspectrophotometry, the most applied technique for the functional characterization of proteins in the crystalline state. Studies on hemoglobins, pyridoxal 5’-phosphate dependent enzymes and green fluorescent protein in the crystalline state have addressed key biological issues, leading to either straightforward structure-function correlations or limitations to structure-based mechanisms.

  2. The growth of Nd:CaWO4 single crystals

    Directory of Open Access Journals (Sweden)

    ALEKSANDAR GOLUBOVIC

    2003-12-01

    Full Text Available CaWO4 doped with 0.8 % at. Nd (Nd:CaWO4 single crystals were grown from the melt in air by the Czochralski technique. The critical diameter dc = 1.0 cm and the critical rate of rotation wc = 30 rpm were calculated from hydrodynamic equations for buoyancy-driven and forced convection. The rate of crystal growth was experimentally obtained to be 6.7 mm/h. For chemical polishing, a solution of 1 part saturated chromic acid (CrO3 in water and 3 parts conc. H3PO4 (85 % at 433 K with an exposure time of 2 h was found to be adequate. A mixture of 1 part concentrated HF and 2 parts chromic acid at room temperature after exposure for 30 min was found to be a suitable etching solution. The lattice parameters a = 0.52404 (6 nm, c = 1.1362 (6 nm and V0 = 0.312 (2 nm3 were determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

  3. Ion implantation of CdTe single crystals

    Science.gov (United States)

    Wiecek, Tomasz; Popovich, Volodymir; Bester, Mariusz; Kuzma, Marian

    2016-12-01

    Ion implantation is a technique which is widely used in industry for unique modification of metal surface for medical applications. In semiconductor silicon technology ion implantation is also widely used for thin layer electronic or optoelectronic devices production. For other semiconductor materials this technique is still at an early stage. In this paper based on literature data we present the main features of the implantation of CdTe single crystals as well as some of the major problems which are likely to occur when dealing with them. The most unexpected feature is the high resistance of these crystals against the amorphization caused by ion implantation even at high doses (1017 1/cm2). The second property is the disposal of defects much deeper in the sample then it follows from the modeling calculations. The outline of principles of the ion implantation is included in the paper. The data based on RBS measurements and modeling results obtained by using SRIM software were taken into account.

  4. Characterization of CuInSe{sub 2} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Shaban, H.T. [Physics Department, Faculty of Science, South Valley University, Qena (Egypt)]. E-mail: htsh2@yahoo.com; Mobarak, M. [Physics Department, Faculty of Science, South Valley University, Qena (Egypt); Nassary, M.M. [Physics Department, Faculty of Science, South Valley University, Qena (Egypt)

    2007-02-15

    High quality CuInSe{sub 2} (CIS) single crystals grown by the vertical Bridgman method. The electrical conductivity, Hall coefficient and thermoelectric power were measured as a function of temperature. The energy gap was found 1.04eV. The crystals were characterized structurally by X-ray diffraction and compositionally by microprobe analyses. Throughout joining the electrical with thermoelectric power measurements many physical parameters were estimated. The effective mass of holes m{sub p}* and electrons m{sub n}* were determined at room temperature and found to be 1.66x10{sup -30} and 8.6x10{sup -36}kg, respectively. Also, at the same temperature the mobility was found to be 956cm{sup 2}/Vs. The hole and electron diffusion coefficients were found to be 23.9 and 35.85cm{sup 2}/s. The relaxation times for holes and electrons were calculated and yielded the values 9.9x10{sup -13} and 7.7x10{sup -18}s, respectively. The diffusion length for holes and electrons was obtained as L{sub p}=4.86x10{sup -6}cm and L{sub n}=16.61x10{sup -9}cm.

  5. Radionuclide annular single crystal scintillator camera with rotating collimator

    Energy Technology Data Exchange (ETDEWEB)

    Genna, S.; Pang, S.-C.

    1986-04-22

    A radionuclide emission tomography camera is described for sensing gamma ray emissions from a source within the field of view consisting of: a fixed, position-sensitive detector means, responsive to the gamma ray emissions and surrounding the field of view for detecting the contact position and the trajectory from which a gamma ray emission originates, the fixed, position-sensitive detector including a single continuous stationary scintillation crystal; rotatable collimator means, disposed between the fixed, position-sensitive detecto means and the field of view, and including at least one array of collimator elements, for restricting and collimating the gamma ray emissions; and means for rotating the collimator means relative to the fixed, position-sensitive detector, for exposing different sections of the position-sensitive detector to the gamma ray emissions in order to view the source from different angles.

  6. Shock Hugoniot behavior of single crystal titanium using atomistic simulations

    Science.gov (United States)

    Mackenchery, Karoon; Dongare, Avinash

    2017-01-01

    Atomistic shock simulations are performed for single crystal titanium using four different interatomic potentials at impact velocities ranging from 0.5 km/s to 2.0 km/s. These potentials comprise of three parameterizations in the formulation of the embedded atom method and one formulation of the modified embedded atom method. The capability of the potentials to model the shock deformation and failure behavior is investigated by computing the shock hugoniot response of titanium and comparing to existing experimental data. In addition, the capability to reproduce the shock induced alpha (α) to omega (ω) phase transformation seen in Ti is investigated. The shock wave structure is discussed and the velocities for the elastic, plastic and the α-ω phase transformation waves are calculated for all the interatomic potentials considered.

  7. Optical studies of neutron-irradiated lithium hydride single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Oparin, D.V.; Pilipenko, G.I.; Tyutyunnik, O.I.; Gavrilov, F.F.; Sulimov, E.M. (Ural' skij Politekhnicheskij Inst., Sverdlovsk (USSR))

    1984-09-01

    Lithium hydride single crystals irradiated with neutrons were studied by the optical method. Wide bands belonging to the large F-aggregate and quasimetallic F-centres and to the metallic lithium colloids were discovered in the absorption spectra at room temperature. The small Fsub(n)-centres and molecular lithium centres were detected at 77 K. From the electron-vibrational structure of the absorption spectra of these centres the energies of acoustic phonons in X, W, L points of the Brillouin zone of lithium hydride have been found out: TA(L)-235 cm/sup -1/, TA(X)-27g cm/sup -1/, TA(W)-327 cm/sup -1/, LA(W)-384 cm/sup -1/, LA(X)-426 cm/sup -1/.

  8. Phonon interactions with methyl radicals in single crystals

    Directory of Open Access Journals (Sweden)

    James W. Wells

    2017-04-01

    Full Text Available The high temperature ESR spectra’s anomalous appearance at very low temperatures for the methyl radical created in single crystals is explained by magnetic dipole interactions with neighboring protons. These protons acting via phonon vibrations induce resonant oscillations with the methyl group to establish a very temperature sensitive ‘‘relaxation’’ mode that allows the higher energy ‘‘E’’ state electrons with spin 12 to ‘‘decay’’ into ‘‘A’’ spin 12 states. Because of the amplitude amplification with temperature, the ‘‘E’’ state population is depleted and the ‘‘A’’ state population augmented to produce the high temperature ESR spectrum. This phenomenon is found to be valid for all but the very highest barriers to methyl group tunneling. In support, a time dependent spin population study shows this temperature evolution in the state populations under this perturbation.

  9. InPBi single crystals grown by molecular beam epitaxy.

    Science.gov (United States)

    Wang, K; Gu, Y; Zhou, H F; Zhang, L Y; Kang, C Z; Wu, M J; Pan, W W; Lu, P F; Gong, Q; Wang, S M

    2014-06-26

    InPBi was predicted to be the most robust infrared optoelectronic material but also the most difficult to synthesize within In-VBi (V = P, As and Sb) 25 years ago. We report the first successful growth of InPBi single crystals with Bi concentration far beyond the doping level by gas source molecular beam epitaxy. The InPBi thin films reveal excellent surface, structural and optical qualities making it a promising new III-V compound family member for heterostructures. The Bi concentration is found to be 2.4 ± 0.4% with 94 ± 5% Bi atoms at substitutional sites. Optical absorption indicates a band gap of 1.23 eV at room temperature while photoluminescence shows unexpectedly strong and broad light emission at 1.4-2.7 μm which can't be explained by the existing theory.

  10. Photoinduced surface voltage mapping study for large perovskite single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaojing; Liu, Yucheng; Gao, Fei; Yang, Zhou [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Laboratory for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi' an 710062 (China); Liu, Shengzhong, E-mail: liusz@snnu.edu.cn [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Laboratory for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi' an 710062 (China); Dalian Institute of Chemical Physics, iChEM, Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian 116023 (China)

    2016-05-02

    Using a series of illumination sources, including white light (tungsten-halogen lamp), 445-nm, 532-nm, 635-nm, and 730-nm lasers, the surface photovoltage (SPV) images were mapped for centimeter-sized CH{sub 3}NH{sub 3}PbX{sub 3} (X = Cl, Br, I) perovskite single crystals using Kelvin probe force microscopy. The significant SPV signals were observed to be wavelength-dependent. We attribute the appreciable SPV to the built-in electric field in the space charge region. This study shines light into the understanding of photoinduced charge generation and separation processes at nanoscale to help advance the development of perovskite solar cells, optoelectronics, laser, photodetector, and light-emitting diode (LED).

  11. Thermal conductivity of single crystal and ceramic AlN

    Science.gov (United States)

    AlShaikhi, A.; Srivastava, G. P.

    2008-04-01

    We have applied the Callaway theory and used a detailed account of three-phonon scattering processes to calculate the thermal conductivity of three AlN single crystal samples containing different amounts of oxygen and two AlN ceramic samples with different grain sizes and oxygen contamination levels. The N-drift contribution to the total conductivity has been quantified. The influence on the thermal conductivity of oxygen-related defects, and grain boundaries in ceramic samples, has been investigated. The theoretical results obtained from this work are in good agreement with available experimental data. Our calculations suggest that the "effective" boundary length is greater than the reported grain size for each of the two ceramic samples studied by Watari et al. [J. Mater. Res. 17, 2940 (2002)].

  12. Low temperature properties of pnictide CrAs single crystal

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    High quality single crystal CrAs was grown by Sn flux method.The results of magnetic susceptibility and electrical resistivity are reported in a temperature range of 2 to 800 K.At low temperatures,a T2 dependence of resistivity is observed showing a Fermi-liquid behavior.The Kadowaki-Woods ratio is found to be 1×10-5 μΩ cm mol2 K2 mJ-2,which fits well to the universal value for many correlated electron systems.At about 270 K,a clear magnetic transition is observed with sharp changes of resistivity and susceptibility.Above 270 K,a linear-temperature dependence of the magnetic susceptibility is observed up to 700 K,which resembles the T-dependent magnetic susceptibility of parents of iron-pnictides superconductors.

  13. Growth of single-crystal YAG fiber optics.

    Science.gov (United States)

    Nie, Craig D; Bera, Subhabrata; Harrington, James A

    2016-07-11

    Single-crystal YAG (Y3Al5O12) fibers have been grown by the laser heated pedestal growth technique with losses as low as 0.3 dB/m at 1.06 μm. These YAG fibers are as long as about 60 cm with diameters around 330 μm. The early fibers were grown from unoriented YAG seed fibers and these fibers exhibited facet steps or ridges on the surface of the fiber. However, recently we have grown fibers using an oriented seed to grow step-free fibers. Scattering losses made on the fibers indicate that the scattering losses are equal to about 30% of the total loss.

  14. Hard x-ray single crystal bi-mirror.

    Science.gov (United States)

    Lyubomirskiy, M; Snigireva, I; Kuznetsov, S; Yunkin, V; Snigirev, A

    2015-05-15

    We report a novel hard x-ray interferometer consisting of two parallel channels manufactured in a single Si crystal by means of microfabrication technology. The sidewall surfaces of the channels, similar to mirrors, scatter at very small incident angles, acting equivalently to narrow micrometer size slits as in the Young double-slit interferometer. Experimental tests of the interferometer were performed at the ESRF ID06 beamline in the energy range from 12 to 16 keV. The interference patterns at different grazing incidence angles were recorded in the near- and far-field. Evaluation of the influence of the channel surface roughness on the visibility of interference fringes was performed. The proposed interferometer design allows the arrangement of mirrors at different split distances.

  15. Photoinduced surface voltage mapping study for large perovskite single crystals

    Science.gov (United States)

    Liu, Xiaojing; Liu, Yucheng; Gao, Fei; Yang, Zhou; Liu, Shengzhong Frank

    2016-05-01

    Using a series of illumination sources, including white light (tungsten-halogen lamp), 445-nm, 532-nm, 635-nm, and 730-nm lasers, the surface photovoltage (SPV) images were mapped for centimeter-sized CH3NH3PbX3 (X = Cl, Br, I) perovskite single crystals using Kelvin probe force microscopy. The significant SPV signals were observed to be wavelength-dependent. We attribute the appreciable SPV to the built-in electric field in the space charge region. This study shines light into the understanding of photoinduced charge generation and separation processes at nanoscale to help advance the development of perovskite solar cells, optoelectronics, laser, photodetector, and light-emitting diode (LED).

  16. Spin injection effect in thin Bi2212 single crystal

    Science.gov (United States)

    Murata, Kenichiro; Otaka, Kazuto; Yamaki, Kazuhiro; Irie, Akinobu

    2017-07-01

    The influence of spin-injection on the in-plane transport properties of thin Bi2Sr2CaCu2Oy (BSCCO) single crystal has been investigated. The in-plane transport measurements without and with spin injection were carried out at 77 K by four terminal method. The in-plane critical current was strongly reduced by injecting the current from Co/Au electrodes formed on the BSCCO bridge with 50 mm wide and 450 nm thick. Furthermore, it was observed that magnetic field dependence of the magnetoresistance shows a hysteresis loop. These results indicate that the in-plane superconductive transport property is affected by the spin-injection related to the magnetization of Co.

  17. Platinum single crystal electrodes for the electrocatalysis of methane oxidation

    Directory of Open Access Journals (Sweden)

    Mayara Munaretto

    2011-03-01

    Full Text Available The main objective of this paper is to characterize the voltammetric profiles of platinum single crystals of low Miller indexes Pt(100 and Pt(110 and study their catalytic activities on the oxidation of methane. In this way, it was developed a metallic surface modified by presence of other metal oxide, which presents catalytic activity for this reaction. It is well known that the electrooxidation of methane (CH4 leads mainly to the formation of CO2 and H2O, however, the oxidation can also lead to the formation of CO, a reaction intermediate that has strong interaction with metal surfaces, such as platinum. This molecule tends to accumulate on the platinum surface and to passive it, due to the self-poisoning, decreasing its catalytic activity. Therefore, the main aim of this work was the development of a platinum electrode modified by deposition of titanium oxide, which presented electrocatalytic properties for the oxidation of methane.

  18. Analysis of ripple formation in single crystal spot welds

    Science.gov (United States)

    Rappaz, M.; Corrigan, D.; Boatner, L. A.

    1997-01-01

    Stationary spot welds have been made at the (001) surface of Fe-l5%Ni-15%Cr single crystals using a Gas Tungsten Arc (GTA). On the top surface of the spot welds, very regular and concentric ripples were observed after solidification by differential interference color microscopy. Their height (typically 1--5 micrometers and spacing, typically approximately 60 micrometers) decreased with the radius of the pool. These ripples were successfully accounted for in terms of capillary-wave theory using the fundamental mode frequency f(sub 0) given by the first zero of the zero-order Bessel function. The spacing d between the ripples was then equated to v(sub s)/f(sub 0), where v(sub s) is the solidification rate. From the measured ripple spacing, the velocity of the pool was deduced as a function of the radius, and this velocity was in good agreement with the results of a heat-flow simulation.

  19. Lateral IBIC characterization of single crystal synthetic diamond detectors

    CERN Document Server

    Giudice, A Lo; Manfredotti, C; Marinelli, M; Milani, E; Picollo, F; Prestopino, G; Re, A; Rigato, V; Verona, C; Verona-Rinati, G; Vittone, E

    2016-01-01

    In order to evaluate the charge collection efficiency (CCE) profile of single-crystal diamond devices based on a p type/intrinsic/metal configuration, a lateral Ion Beam Induced Charge (IBIC) analysis was performed over their cleaved cross sections using a 2 MeV proton microbeam. CCE profiles in the depth direction were extracted from the cross-sectional maps at variable bias voltage. IBIC spectra relevant to the depletion region extending beneath the frontal Schottky electrode show a 100% CCE, with a spectral resolution of about 1.5%. The dependence of the width of the high efficiency region from applied bias voltage allows the constant residual doping concentration of the active region to be evaluated. The region where the electric field is absent shows an exponentially decreasing CCE profile, from which it is possible to estimate the diffusion length of the minority carriers by means of a drift-diffusion model.

  20. Shock compression experiments on Lithium Deuteride single crystals.

    Energy Technology Data Exchange (ETDEWEB)

    Knudson, Marcus D.; Desjarlais, Michael Paul; Lemke, Raymond W.

    2014-10-01

    S hock compression exper iments in the few hundred GPa (multi - Mabr) regime were performed on Lithium Deuteride (LiD) single crystals . This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17 - 32 km/s. Measurements included pressure, density, and temperature between %7E200 - 600 GPa along the Principal Hugoniot - the locus of end states achievable through compression by large amplitude shock waves - as well as pressure and density of re - shock states up to %7E900 GPa . The experimental measurements are compared with recent density functional theory calculations as well as a new tabular equation of state developed at Los Alamos National Labs.

  1. Isothermal equation of state of a lithium fluoride single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.Y.

    1975-01-01

    An isothermal equation of state of a LiF single crystal was determined from length change measurements of the specimen as a function of hydrostatic pressure up to approximately 7 kbars at 28 to 41/sup 0/C. The length change was measured with an accuracy of approximately 500 A by using a Fabry Perot type He--Ne laser interferometer for a 1-m long specimen at temperatures constant to less than 0.002/sup 0/C. Several two- and three-parameter equations of state were used in analyzing the measured pressure-volume data. The computer fit for each equation of state determines not only the value of its parameters but also the standard deviations associated with them and one dependent variable, either pressure or volume. With the parameters determined, the equations of state are extrapolated to approximately 5 megabars in order to see discrepancies. Using the Born model of ionic solids, two equations of state were derived both from a power law potential and from an exponential form for the repulsive energy of alkali metal halides and used to fit the pressure-volume data of a LiF single crystal. They are also extrapolated to approximately 5 megabars. The Birch's two-parameter equation and the Grover, Getting, and Kennedy equation are indistinguishable from the two equations of state derived from the Born model for pressures approximately equal to or less than 800 kbars within +-20 kbars. The above four equations of state also fit closely the Pagannone and Drickamer static compression data, the Christian shock wave data, and the Kormer et al. shock wave data. The isothermal bulk modulus and its first pressure derivative at atmospheric pressure and 28.83/sup 0/C are 664.5 +- 0.5 kbars and 5.40 +- 0.18, respectively, in close agreement with those values ultrasonically measured by R. A. Miller and C. S. Smith. (auth)

  2. Process development for single-crystal silicon solar cells

    Science.gov (United States)

    Bohra, Mihir H.

    Solar energy is a viable, rapidly growing and an important renewable alternative to other sources of energy generation because of its abundant supply and low manufacturing cost. Silicon still remains the major contributor for manufacturing solar cells accounting for 80% of the market share. Of this, single-crystal solar cells account for half of the share. Laboratory cells have demonstrated 25% efficiency; however, commercial cells have efficiencies of 16% - 20% resulting from a focus on implementation processes geared to rapid throughput and low cost, thereby reducing the energy pay-back time. An example would be the use of metal pastes which dissolve the dielectric during the firing process as opposed to lithographically defined contacts. With current trends of single-crystal silicon photovoltaic (PV) module prices down to 0.60/W, almost all other PV technologies are challenged to remain cost competitive. This presents a unique opportunity in revisiting the PV cell fabrication process and incorporating moderately more expensive IC process practices into PV manufacturing. While they may drive the cost toward a 1/W benchmark, there is substantial room to "experiment", leading to higher efficiencies which will help maintain the overall system cost. This work entails a turn-key process designed to provide a platform for rapid evaluation of novel materials and processes. A two-step lithographic process yielding a baseline 11% - 13% efficient cell is described. Results of three studies have shown improvements in solar cell output parameters due to the inclusion of a back-surface field implant, a higher emitter doping and also an additional RCA Clean.

  3. Method for the preparation of inorganic single crystal and polycrystalline electronic materials

    Science.gov (United States)

    Groves, W. O. (Inventor)

    1969-01-01

    Large area, semiconductor crystals selected from group 3-5 compounds and alloys are provided for semiconductor device fabrication by the use of a selective etching operation which completely removes the substrate on which the desired crystal was deposited. The substrate, selected from the same group as the single crystal, has a higher solution rate than the epitaxial single crystal which is essentially unaffected by the etching solution. The preparation of gallium phosphide single crystals using a gallium arsenide substrate and a concentrated nitric acid etching solution is described.

  4. Studies on crystal growth and physical properties of 4-(dimethylamino)benzaldehyde-2,4-dinitroaniline single crystal

    Science.gov (United States)

    Jebin, R. P.; Suthan, T.; Rajesh, N. P.; Vinitha, G.; Dhas, S. A. Britto

    2016-07-01

    The organic material 4-(dimethylamino)benzaldehyde-2,4-dinitroaniline has been grown by slow evaporation technique. Single crystal and Powder X-ray diffraction studies have been carried out to conform the grown crystal. FTIR and FT-Raman spectra were recorded to identify the functional groups present in the crystal. The optical property of the grown crystal was analysed by UV-Vis-NIR measurement. The thermal property of the grown crystal was analysed by thermogravimetric (TG) and differential thermal analyses (DTA). Thermal diffusivity of the grown crystal was analysed by Photo acoustic spectroscopic (PAS) studies. The third order nonlinear optical properties of 4-(dimethylamino)benzaldehyde-2,4-dinitroaniline was measured by the Z-scan technique using 532 nm diode pumped continuous wave (CW) Nd:YAG laser. The mechanical property of the grown crystal was analysed by using microhardness studies.

  5. Digital microfluidic high-throughput printing of single metal-organic framework crystals.

    Science.gov (United States)

    Witters, Daan; Vergauwe, Nicolas; Ameloot, Rob; Vermeir, Steven; De Vos, Dirk; Puers, Robert; Sels, Bert; Lammertyn, Jeroen

    2012-03-08

    The first microfluidic method for accurately depositing monodisperse single MOF crystals is presented, enabling unprecedented high-throughput, yet flexible single-crystal printing. Individual droplets of MOF precursor solutions are actuated over a matrix of hydrophilic-in-hydrophobic micropatterns for the controlled generation of femtoliter droplets. As such, thousands of monodisperse single MOF crystals are printed per second in a desired pattern, without the use of impractically expensive equipment.

  6. The Strength of PIN-PMN-PT Single Crystals under Bending with a Longitudinal Electric Field

    Science.gov (United States)

    2011-04-06

    The strength of PIN– PMN – PT single crystals under bending with a longitudinal electric field This article has been downloaded from IOPscience. Please...COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE The Strength Of PIN- PMN - PT Single Crystals Under Bending With A Longitudinal Electric Field... PMN ? PT ) single crystals was measured using a four point bending apparatus with a longitudinal electric field applied to the bar during bending. The

  7. Synthesis, Crystal Growth and Characterization of bis Dl-Valine Picrate Single Crystal for Second-Order Nonlinear Optical Applications

    Science.gov (United States)

    Silambarasan, A.; Krishna Kumar, M.; Sudhahar, S.; Thirunavukkarasu, A.; Mohan Kumar, R.; Umarani, P. R.

    2013-08-01

    An organic compound Bis DL-Valine picrate (BDLVP) was synthesized successfully and single crystal was grown by slow evaporation solution growth method. The presence of functional groups in the compound was identified by FTIR spectral analysis. Single crystal X-ray diffraction study revealed that the grown crystal belongs to P21/n space group of monoclinic crystal system. Powder X-ray diffraction pattern was recorded to know the crystalline perfection of the grown crystal. The reaction mechanism, thermal decomposition stages and thermal stability of the grown crystal were studied by using TG/DTA analysis. From the UV-visible spectral study, the electronic band gap energy (Eg) of the grown crystal was found to be 2.43 eV. The second harmonic generation (SHG) efficiency of grown crystal was found to be 1.3 times higher than KDP crystal by using Kurtz powder SHG technique. The microhardness property of the grown crystal was examined by Vicker's microhardness test.

  8. Phase-field modeling on morphological landscape of isotactic polystyrene single crystals.

    Science.gov (United States)

    Xu, Haijun; Matkar, Rushikesh; Kyu, Thein

    2005-07-01

    Spatio-temporal growth of isotactic polystyrene single crystals during isothermal crystallization has been investigated theoretically based on the phase field model by solving temporal evolution of a nonconserved phase order parameter coupled with a heat conduction equation. In the description of the total free energy, an asymmetric double-well local free energy density has been adopted to represent the metastable melt and the stable solid crystal. Unlike the small molecule systems, polymer crystallization rarely reaches thermodynamic equilibrium; most polymer crystals are kinetically stabilized in some metastable states. To capture various metastable polymer crystals, the phase field crystal order parameter at the solidification potential has been treated to be supercooling dependent such that it can assume an intermediate value between zero (melt) and unity (perfect crystal), reflecting imperfect polycrystalline nature of polymer crystals. Two-dimensional simulations exhibit various single crystal morphologies of isotactic polystyrene crystals such as faceted hexagonal patterns transforming to nonfaceted snowflakes with increasing supercooling. Of particular interest is that heat liberation from the crystallizing front influences the curvature of the crystal-melt interface, leading to directional growth of lamellar tips and side branches. The landscape of these morphological textures has been established as a function of anisotropy of surface energy and supercooling. With increasing supercooling and decreasing anisotropy, the hexagonal single crystal transforms to the dense lamellar branching morphology in conformity with the experimental findings.

  9. Advanced Electroactive Single Crystal and Polymer Actuator Concepts for Passive Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes large stroke and high precision piezoelectric single crystal and electroactive polymer actuator concepts?HYBrid Actuation System (HYBAS)...

  10. Cryogenic Clamp-on Ultrasonic Flowmeters using Single Crystal Piezoelectric Transducers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Clamp-on ultrasound cryogenic flowmeters using single crystal piezoelectric transducers are proposed to enable reliable, accurate cryogenic instrumentation needs in...

  11. Single-walled Carbon Nanotubes Regularly Aligned in Channels of Zeolite Single Crystal

    Institute of Scientific and Technical Information of China (English)

    Zi Kang Tang; Handong Sun; Jiannong Wang

    2000-01-01

    @@ We report the synthesis of single-wall carbon nanotubes (SWCNs) formed in 1-nm-sized channels of zeolite crystal by pyrolysis of tripropylamine molecules. The SWCNs are mono-sized and parallelly aligned along the crystal direction. In the present paper, we report the polarized Raman spectra measured for the wellaligned SWCNs, which gives us information about structural symmetry. Electrical transport properties of the SWNTs are measured in the temperature range of 0.3 K ~ 300 K. The conductivity of the SWCNs is monotonically decreased with decreasing temperature. The observed temperature dependence of zero-field conductance, In(σ) ~ 1/√T, could be explained well in terms of electron localization caused by imperfections and impurities in the nanotubes.

  12. Single crystal nuclear magnetic resonance in spinning powders

    Science.gov (United States)

    Pell, Andrew J.; Pintacuda, Guido; Emsley, Lyndon

    2011-10-01

    We present a method for selectively exciting nuclear magnetic resonances (NMRs) from well-defined subsets of crystallites from a powdered sample under magic angle spinning. Magic angle spinning induces a time dependence in the anisotropic interactions, which results in a time variation of the resonance frequencies which is different for different crystallite orientations. The proposed method exploits this by applying selective pulses, which we refer to as XS (for crystallite-selective) pulses, that follow the resonance frequencies of nuclear species within particular crystallites, resulting in the induced flip angle being orientation dependent. By selecting the radiofrequency field to deliver a 180 ○ pulse for the target orientation and employing a train of such pulses combined with cogwheel phase cycling, we obtain a high degree of orientational selectivity with the resulting spectrum containing only contributions from orientations close to the target. Typically, this leads to the selection of between 0.1% and 10% of the crystallites, and in extreme cases to the excitation of a single orientation resulting in single crystal spectra of spinning powders. Two formulations of this method are described and demonstrated with experimental examples on [1 - 13C]-alanine and the paramagnetic compound Sm2Sn2O7.

  13. Enhanced Catalysis Activity in a Coordinatively Unsaturated Cobalt-MOF Generated via Single-Crystal-to-Single-Crystal Dehydration.

    Science.gov (United States)

    Ren, Hai-Yun; Yao, Ru-Xin; Zhang, Xian-Ming

    2015-07-06

    Hydrothermal reaction of Co(NO3)2 and terphenyl-3,2",5",3'-tetracarboxyate (H4tpta) generated Co3(OH)2 chains based 3D coordination framework Co3(OH)2(tpta)(H2O)4 (1) that suffered from single-crystal-to-single-crystal dehydration by heating at 160 °C and was transformed into dehydrated Co3(OH)2(tpta) (1a). During the dehydration course, the local coordination environment of part of the Co atoms was transformed from saturated octahedron to coordinatively unsaturated tetrahedron. Heterogenous catalytic experiments on allylic oxidation of cyclohexene show that dehydrated 1a has 6 times enhanced catalytic activity than as-synthesized 1 by using tert-butyl hydroperoxide (t-BuOOH) as oxidant. The activation energy for the oxidation of cylcohexene with 1a catalyst was 67.3 kJ/mol, far below the value with 1 catalysts, which clearly suggested that coordinatively unsaturated Co(II) sites in 1a have played a significant role in decreasing the activation energy. It is interestingly found that heterogeneous catalytic oxidation of cyclohexene in 1a not only gives the higher conversion of 73.6% but also shows very high selectivity toward 2-cyclohexene-1-one (ca. 64.9%), as evidenced in high turnover numbers (ca. 161) based on the open Co(II) sites of 1a catalyst. Further experiments with a radical trap indicate a radical chain mechanism. This work demonstrates that creativity of coordinatively unsaturated metal sites in MOFs could significantly enhance heterogeneous catalytic activity and selectivity.

  14. Crystal Growth and Characterization of Ca3NbGa3Si2O14 Single Crystal

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Single crystals of Ca3NbGa3Si2O14 (CNGS) with ordered Ca3Ga2Ge4O14 (CGG) structure were successfully grown from stoichiometric melts by conventional Czochralski technique along the a-axis and two large (001) facets and two small (100) facets appear in every crystal. An arrangement of parallel steps and a clear height change were observed in (001) facet by atomic force microscopy (AFM). High-resolution X-ray diffraction (HRXRD) results indicate that CNGS crystals have good quality and free low-angle boundaries. The crystals also exhibit good optical quality and high optical transmittance in c-direction.

  15. Fabrication of Single Crystal MgO Capsules

    Science.gov (United States)

    Danielson, Lisa

    2012-01-01

    A method has been developed for machining MgO crystal blocks into forms for containing metallic and silicate liquids at temperatures up to 2,400 C, and pressures up to at least 320 kilobars. Possible custom shapes include tubes, rods, insulators, capsules, and guides. Key differences in this innovative method include drilling along the crystallographic zone axes, use of a vibration minimizing material to secure the workpiece, and constant flushing of material swarf with a cooling medium/lubricant (water). A single crystal MgO block is cut into a section .5 mm thick, 1 cm on a side, using a low-speed saw with a 0.004 blade. The cut is made parallel to the direction of cleavage. The block may be cut to any thickness to achieve the desired length of the piece. To minimize drilling vibrations, the MgO block is mounted on a piece of adhesive putty in a vise. The putty wad cradles the bottom half of the entire block. Diamond coring tools are used to drill the MgO to the desired custom shape, with water used to wet and wash the surface of swarf. Compressed air may also be used to remove swarf during breaks in drilling. The MgO workpiece must be kept cool at all times with water. After all the swarf is rinsed off, the piece is left to dry overnight. If the workpiece is still attached to the base of the MgO block after drilling, it may be cut off by using a diamond cutoff wheel on a rotary hand tool or by using a low-speed saw.

  16. Single-crystal elastic constants of natural ettringite

    KAUST Repository

    Speziale, Sergio

    2008-07-01

    The single-crystal elastic constants of natural ettringite were determined by Brillouin spectroscopy at ambient conditions. The six non-zero elastic constants of this trigonal mineral are: C11 = 35.1 ± 0.1 GPa, C12 = 21.9 ±0.1 GPa, C13 = 20.0 ± 0.5 GPa, C14 = 0.6 ± 0.2 GPa, C33 = 55 ± 1 GPa, C44 = 11.0 ± 0.2 GPa. The Hill average of the aggregate bulk, shear modulus and the polycrystal Young\\'s modulus and Poisson\\'s ratio are 27.3 ± 0.9 GPa, 9.5 ± 0.8 GPa, 25 ± 2 GPa and 0.34 ± 0.02 respectively. The longitudinal and shear elastic anisotropy are C33/C11 = 0.64 ± 0.01 and C66/C44 =0.60 ± 0.01. The elastic anisotropy in ettringite is connected to its crystallographic structure. Stiff chains of [Al(OH)6]3- octahedra alternating with triplets of Ca2+ in eight-fold coordination run parallel to the c-axis leading to higher stiffness along this direction. The determination of the elastic stiffness tensor can help in the prediction of the early age properties of cement paste when ettringite crystals precipitate and in the modeling of both internal and external sulfate attack when secondary ettringite formation leads to expansion of concrete. © 2008 Elsevier Ltd. All rights reserved.

  17. Radiation-electromagnetic effect in germanium single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kikoin, I.K.; Kikoin, L.I.; Lazarev, S.D.

    1980-10-01

    An experimental study was made of the radiation-electromagnetic effect in germanium single crystals when excess carriers were generated by bombardment with ..cap alpha.. particles, protons, or x rays in magnetic fields up to 8 kOe. The source of ..cap alpha.. particles and protons was a cyclotron and x rays were provided by a tube with a copper anode. The radiation-electromagnetic emf increased linearly on increase in the magnetic field and was directly proportional to the flux of charged particles at low values of the flux, reaching saturation at high values of the flux (approx.5 x 10/sup 11/ particles .cm/sup -2/ .sec/sup -1/). In the energy range 4--40 MeV the emf was practically independent of the ..cap alpha..-particle energy. The sign of the emf was reversed when samples with a ground front surface were irradiated. Measurements of the photoelectromagnetic and Hall effects in the ..cap alpha..-particle-irradiated samples showed that a p-n junction was produced by these particles and its presence should be allowed for in investigations of the radiation-electromagnetic effect. The measured even radiation-electromagnetic emf increased quadratically on increase in the magnetic field. An investigation was made of the barrier radiation-voltaic effect (when the emf was measured between the irradiated and unirradiated surfaces). Special masks were used to produce a set of consecutive p-n junctions in germanium crystals irradiated with ..cap alpha.. particles. A study of the photovoltaic and photoelectromagnetic effects in such samples showed that the method could be used to increase the efficiency of devices utilizing the photoelectromagnetic effect.

  18. Thermal behaviour of strontium tartrate single crystals grown in gel

    Indian Academy of Sciences (India)

    M H Rahimkutty; K Rajendra Babu; K Sreedharan Pillai; M R Sudarsana Kumar; C M K Nair

    2001-04-01

    Thermal behaviour of strontium tartrate crystals grown with the aid of sodium metasilicate gel is investigated using thermogravimetry (TG) and differential thermal analysis (DTA). Effect of magnetic field and dopant (Pb)2+ on the crystal stability is also studied using thermal analysis. This study reveals that water molecules are locked up in the lattice with different strengths in the grown crystals.

  19. Synthesis, crystal growth, solubility, structural, optical, dielectric and microhardness studies of Benzotriazole-4-hydroxybenzoic acid single crystals

    Science.gov (United States)

    Silambarasan, A.; Krishna Kumar, M.; Thirunavukkarasu, A.; Mohan Kumar, R.; Umarani, P. R.

    2015-06-01

    Organic Benzotriazole-4-hydroxybenzoic acid (BHBA), a novel second-order nonlinear optical single crystal was grown by solution growth method. The solubility and nucleation studies were performed for BHBA crystal at different temperatures 30, 35, 40 45 and 50 °C. Single crystal X-ray diffraction study reveals that the BHBA belongs to Pna21 space group of orthorhombic crystal system. The crystal perfection of BHBA was examined from powder and high resolution X-ray diffraction analysis. UV-visible and photoluminescence spectra were recorded to study its transmittance and excitation, emission behaviors respectively. Kurtz powder second harmonic generation test reveals that, the frequency conversion efficiency of BHBA is 3.7 times higher than that of potassium dihydrogen phosphate (KDP) crystal. The dielectric constant and dielectric loss values were estimated for BHBA crystal at various temperatures and frequencies. The mechanical property of BHBA crystal was studied on (110), (010) and (012) planes by using Vicker's microhardness test. The chemical etching study was performed on (012) facet of BHBA crystal to analyze its growth feature.

  20. Synthesis and ultrastructure of plate-like apatite single crystals as a model for tooth enamel

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Zhi, E-mail: zhuang@meiji.ac.jp [Department of Applied Chemistry, School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Yoshimura, Hideyuki, E-mail: hyoshi@isc.meiji.ac.jp [Department of Physics, School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Aizawa, Mamoru, E-mail: mamorua@isc.meiji.ac.jp [Department of Applied Chemistry, School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan)

    2013-07-01

    Hydroxyapatite (HAp) is an inorganic constituent compound of human bones and teeth, with superior biocompatibility and bioactivity characteristics. Its crystal structure is hexagonal, characterized by a(b)- and c-planes. In vertebrate long bones, HAp crystals have a c-axis orientation, while in tooth enamel, they have an a(b)-axis orientation. Many methods can be used to synthesize c-axis oriented HAp single crystals; however, to the best of our knowledge, there have been no reports on a synthesis method for a(b)-axis oriented HAp single crystals. In this study, we successfully synthesized plate-like HAp crystals at the air–liquid interface of a starting solution via an enzyme reaction of urea with urease. Crystal phase analysis and ultrastructure observations were carried out, and the results indicated that the particles were single crystals, with almost the same a(b)-axis orientation as tooth enamel. It is hoped that by utilizing their unique surface charge and atomic arrangement, the resulting particles can be used as a high-performance biomaterial, capable of adsorbing bio-related substances and a model for tooth enamel. - Highlights: ► Synthesis of plate-like hydroxyapatite crystals at air–liquid interface ► Ultrastructural analysis of plate-like hydroxyapatite crystals ► Plate-like hydroxyapatite single crystals with a high a(b)-axis orientation ► Plate-like hydroxyapatite single crystals as a model for tooth enamel.

  1. Synthesis, growth, structural, thermal and optical studies of pyrrolidinium-2-carboxylate-4-nitrophenol single crystals

    Science.gov (United States)

    Swarna Sowmya, N.; Sampathkrishnan, S.; Vidyalakshmi, Y.; Sudhahar, S.; Mohan Kumar, R.

    2015-06-01

    Organic nonlinear optical material, pyrrolidinium-2-carboxylate-4-nitrophenol (PCN) was synthesized and single crystals were grown by slow evaporation solution growth method. Single crystal X-ray diffraction analysis confirmed the structure and lattice parameters of PCN crystals. Infrared, Raman and NMR spectral analyses were used to elucidate the functional groups present in the compound. The thermal behavior of synthesized compound was studied by thermogravimetric and differential scanning calorimetry (TG-DSC) analyses. The photoluminescence property was studied by exciting the crystal at 360 nm. The relative second harmonic generation (SHG) efficiency of grown crystal was estimated by using Nd:YAG laser with fundamental wavelength of 1064 nm.

  2. SINGLE-CRYSTAL SAPPHIRE OPTICAL FIBER SENSOR INSTRUMENTATION

    Energy Technology Data Exchange (ETDEWEB)

    A. Wang; G. Pickrell; R. May

    2002-09-10

    Accurate measurement of temperature is essential for the safe and efficient operation and control of a wide range of industrial processes. Appropriate techniques and instrumentation are needed depending on the temperature measurement requirements in different industrial processes and working environments. Harsh environments are common in many industrial applications. These harsh environments may involve extreme physical conditions, such as high-temperature, high-pressure, corrosive agents, toxicity, strong electromagnetic interference, and high-energy radiation exposure. Due to these severe environmental conditions, conventional temperature sensors are often difficult to apply. This situation has opened a new but challenging opportunity for the sensor society to provide robust, high-performance, and cost-effective temperature sensors capable of operating in those harsh environments. The focus of this research program has been to develop a temperature measurement system for temperature measurements in the primary and secondary stages of slagging gasifiers. For this application the temperature measurement system must be able to withstand the extremely harsh environment posed by the high temperatures and corrosive agents present in these systems. Real-time, accurate and reliable monitoring of temperature for the coal gasification process is important to realize the full economic potential of these gasification systems. Long life and stability of operation in the high temperature environment is essential for the temperature measurement system to ensure the continuous running of the coal gasification system over the long term. In this high temperature and chemically corrosive environment, rather limited high temperature measurement techniques such as high temperature thermocouples and optical/acoustic pyrometers are available, each with their own limitations. In this research program, five different temperature sensing schemes based on the single crystal sapphire

  3. Growth, Structural And Optical Studies On Bis L-alanine Lithium Chloride (BLALC) Single Crystal

    Science.gov (United States)

    Rose, A. S. J. Lucia; Selvarajan, P.; Perumal, S.

    2011-10-01

    Bis L-alanine Lithium Chloride (BLALC) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 15 x 9 x 4 mm3 have been obtained in 28 days. The grown crystals were colourless and transparent. Single crystal X-ray diffraction (XRD) study showed that BLALC belongs to orthorhombic system with a non-centro-symmetric space group P212121. The crystallinity of BLALC crystal was confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. The functional groups of the grown crystals have been identified by FTIR studies. UV-visible transmittance spectrum was recorded to study the optical transparency of BLALC crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique.

  4. Crystalline perfection, spectroscopic investigations and transport properties of trisglycine zinc chloride NLO single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sugandhi, K.; Dinakaran, S.; Jose, M.; Uthrakumar, R. [Department of Physics, Loyola College, Chennai 600 034 (India); Jeya Rejendran, A. [Department of Chemistry, Loyola College, Chennai 600 034 (India); Bhagvannarayana, G. [CGC section, National Physical Laboratory, New Delhi 110 012 (India); Joseph, V. [Department of Physics, Loyola College, Chennai 600 034 (India); Jerome Das, S., E-mail: sjeromedas2004@yahoo.co [Department of Physics, Loyola College, Chennai 600 034 (India)

    2010-09-15

    Bulk single crystals of trisglycine zinc chloride have been grown from aqueous solution by slow cooling technique. Single crystal and powder XRD analyses confirmed orthorhombic crystal structure with non-centrosymmetric space group Pbn2{sub 1.} High resolution X-ray diffraction results have established that the quality of the grown crystal is quite good for device fabrication. The crystal was characterized by FTIR and NMR spectral analyses. Optical absorption studies show that the material has very low absorption in the wavelength range 240-2000 nm. The analysis of absorption coefficient in the absorption region reveals a direct band gap of 4.21 eV. The crystal possesses remarkable thermal stability up to 229 {sup o}C. Photoconductivity studies of the grown crystal revealed the positive photoconducting nature. The grown crystal exhibited considerable hardness anisotropy with Vicker's hardness tester. Dielectric constant and dielectric loss were calculated by varying frequencies at different temperatures.

  5. Modeling of Crystal Orientations in Laser Powder Deposition of Single Crystal Material

    Science.gov (United States)

    Qi, Huan; Liu, Zhaoyang

    This paper presents a numerical model which simulates the dynamic molten pool formation and the crystal orientations of solidified SX alloy in a multi-layer laser powder deposition process. Based on the mathematical model of coaxial laser direct deposition, the effect of parameters (laser power, scanning speed, powder feed rate) on the tendency to form [001] direction expitaxial grains during solidification was evaluated. In the transient three- dimensional model, physical phenomena including heat transfer, melting, grain formation during solidification, mass addition, and fluid flow in the melt pool, were modeled in a self-consistent manner. The temperature fields, fluid flow velocity, clad geometry (width, height and melt pool depth) and grain formation in melting pool of single layer are predicted.

  6. Growth, Structural and Microhardness Studies on New Semiorganic Single Crystals of Calcium Para Nitrophenolate Dihydrate

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Good quality crystals of calcium p-nitrophenolate (NPCa) were grown from saturated solution by slow evaporation method. The crystal structure analysis and the molecular arrangement of these crystals were determined using X-ray diffraction (XRD). From single crystal XRD studies, NPCa is found to be crystallized in the monoclinic system with a space group P21/n. The functional groups of the material were confirmed qualitatively by FTIR (Fourier transform infrared spectroscopy) spectral analysis. Optical absorption studies reveal the absorption region and microhardness studies were carried out to confirm the mechanical behaviour of the crystals.

  7. Growth of BPO4 single crystals from Li2Mo3O10 flux

    Science.gov (United States)

    Xu, Guogang; Li, Jing; Han, Shujuan; Guo, Yongjie; Wang, Jiyang

    2010-12-01

    Transparent single crystal of BPO4 with a typical sizes of 5 × 7 × 9 mm3 have been grown by the top-seeded solution growth (TSSG) slow-cooling method using Li2Mo3O10 as the flux. X-ray powder diffraction result shows that the as-grown crystal was well crystallized and indexed in a tetragonal system. The processing parameters and the effects of the flux on the crystal growth were investigated.

  8. Piezoelectric properties of Sr3Ga2Ge4O14 single crystals

    Indian Academy of Sciences (India)

    Anhua Wu; Jiayue Xu; Juan Zhou; Hui Shen

    2007-04-01

    A new piezoelectric single crystal, Sr3Ga2Ge4O14 (SGG), has been grown successfully by the vertical Bridgman method with crucible-sealing technique. SGG crystal up to 2″ in diameter has been obtained. The relative dielectric constants, the piezoelectric strain constants, elastic compliance constants and electromechanical coupling factors have been determined with resonance and anti-resonance frequencies method by using the impedance analyzer (Agilent 4294A). The results show that the piezoelectric strain constants and electromechanical coupling factors of SGG single crystal are higher than those of LGS single crystals making it a potential substrate material for surface-acoustic wave applications.

  9. Preparation and Raman Spectrum of Rutile Single Crystals Using Floating Zone Method

    Institute of Scientific and Technical Information of China (English)

    GUO Xing-Yuan; XU Da-Peng; DING Zhan-Hui; SU Wen-Hui

    2006-01-01

    With anatase-type titanium dioxide as the raw materials, the rutile type titanium dioxide single crystal is prepared using the floating zone method. The results ofXRD measurement show that the grown crystal is highly crystalline with a rutile structure, which has orientation to the c-axis. The four Raman vibration characteristic peaks (143, 240, 450 and 610cm-1 ) at room temperature show that the crystalline structure of the single crystal is a typical rutile phase, meanwhile a new Raman peak at around 690cm-1 is found. The results of the Raman measurement at various temperatures for the single crystal show that the Raman frequency shifts are different.

  10. Design and fabrication of PIN-PMN-PT single-crystal high-frequency ultrasound transducers.

    Science.gov (United States)

    Sun, Ping; Zhou, Qifa; Zhu, Benpeng; Wu, Dawei; Hu, Changhong; Cannata, Jonathan M; Tian, Jin; Han, Pengdi; Wang, Gaofeng; Shung, K Kirk

    2009-12-01

    High-frequency PIN-PMN-PT single crystal ultrasound transducers at center frequencies of 35 MHz and 60 MHz were successfully fabricated using lead indium niobate-lead magnesium niobate-lead titanate (0.23PIN- 0.5PMN-0.27PT) single crystal. The new PIN-PMN-PT single crystal has higher coercivity (6.0 kV/cm) and higher Curie temperature (160 degrees C) than PMN-PT crystal. Experimental results showed that the PIN-PMN-PT transducers have similar performance but better thermal stability compared with the PMN-PT transducers.

  11. Design and Fabrication of PIN-PMN-PT Single-Crystal High-Frequency Ultrasound Transducers

    OpenAIRE

    Sun, Ping; Zhou, Qifa; Zhu, Benpeng; WU, DAWEI; Hu, Changhong; Cannata, Jonathan M.; Tian, Jin; Han, Pengdi; Wang, Gaofeng; Shung, K. Kirk

    2009-01-01

    High-frequency PIN-PMN-PT single crystal ultrasound transducers at center frequencies of 35 MHz and 60 MHz were successfully fabricated using lead indium niobate-lead magnesium niobate-lead titanate (0.23PIN-0.5PMN-0.27PT) single crystal. The new PIN-PMN-PT single crystal has higher coercivity (6.0 kV/cm) and higher Curie temperature (160°C) than PMN-PT crystal. Experimental results showed that the PIN-PMN-PT transducers have similar performance but better thermal stability compared with the ...

  12. Fracture of Fe-3wt.% Si single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Prahl, J. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic); Machova, A. [Institute of Thermomechanics, Academy of Sciences of the Czech Republic, Dolejskova 5, 182 00 Prague 8 (Czech Republic); Landa, M. [Institute of Thermomechanics, Academy of Sciences of the Czech Republic, Dolejskova 5, 182 00 Prague 8 (Czech Republic); Hausild, P. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic)], E-mail: Petr.Hausild@fjfi.cvut.cz; Karlik, M. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic); Spielmannova, A. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic); Clavel, M. [Ecole Centrale Paris, LMSS-Mat, CNRS UMR 8579, Grande Voie des Vignes, 92295 Chatenay-Malabry (France); Haghi-Ashtiani, P. [Ecole Centrale Paris, LMSS-Mat, CNRS UMR 8579, Grande Voie des Vignes, 92295 Chatenay-Malabry (France)

    2007-07-25

    The ductile to brittle transition in {alpha}-iron was studied on four oriented single crystals of a Fe-3wt.% Si alloy using tensile tests of flat-notched specimens, scanning and transmission electron microscopy. The experimental results are compared with molecular dynamic simulations. Single-edge notched specimens were loaded in tension at room temperature, the crack propagated in a (001) plane and in the [1-bar10] direction. The crosshead speed was changed in the range from 0.1 to 5.0mm/min. Under the lowest loading rate, a plastic zone was formed at the notch tip, faster loading lead to brittle fracture. Fractographic analysis of one specimen ruptured at 1mm/min loading showed flat cleavage facets and tongues formed by the interaction of the principal crack with deformation twins. Besides the tongues, the fracture surface of the second sample ruptured at the same loading rate exhibited signs of plastic deformation. In the first specimen, transmission electron microscopy in the vicinity of the fracture surface confirmed deformation twinning and a very low dislocation density. In the second specimen, deformation twinning was assisted by slip of dislocations in the <111> {l_brace}112{r_brace} slip system. Molecular dynamics simulations confirmed that the crack growth has a more brittle character with increasing loading rates. At a slower loading rate, the crack growth is more difficult since it is impeded by emission of shielding dislocations from the crack tip in the <111> {l_brace}112{r_brace} slip system. Twin formation at the crack front was detected in simulations with edge cracks.

  13. What is the role of rhenium in single crystal superalloys?

    Directory of Open Access Journals (Sweden)

    Mottura Alessandro

    2014-01-01

    Full Text Available Rhenium plays a critical role in single-crystal superalloys –its addition to first generation alloys improves creep life by a factor of at least two, with further benefits for fatigue performance. Its use in alloys such as PWA1484, CMSX-4 and Rene N5 is now widespread, and many in this community regard Re as the “magic dust”. In this paper, the latest thinking concerning the origins of the “rhenium-effect” is presented. We start by reviewing the hypothesis that rhenium clusters represent barriers to dislocation motion. Recent atom probe tomography experiments have shown that Re may instead form a solid solution with Ni at low concentrations (< 7 at.%. Density functional theory calculations indicate that, in the solid solution, short range ordering of Re may be expected. Finally, Re has been shown to diffuse slowly in the γ-Ni phase. Calculations using a semi-analytical dislocation climb/glide model based upon the work of McLean and Dyson have been used to rationalise the composition-dependence of creep deformation in these materials. All evidence points to two important factors: (i the preferred partitioning of Re to the γ phase, where dislocation activity preferentially occurs during the tertiary creep regime and (ii a retardation effect on dislocation segments at γ/γ′ interfaces, which require non-conservative climb and thus an associated vacancy flux.

  14. Buckling of Single-Crystal Silicon Nanolines under Indentation

    Directory of Open Access Journals (Sweden)

    Min K. Kang

    2008-01-01

    Full Text Available Atomic force microscope-(AFM- based indentation tests were performed to examine mechanical properties of parallel single-crystal silicon nanolines (SiNLs of sub-100-nm line width, fabricated by a process combining electron-beam lithography and anisotropic wet etching. The SiNLs have straight and nearly atomically flat sidewalls, and the cross section is almost perfectly rectangular with uniform width and height along the longitudinal direction. The measured load-displacement curves from the indentation tests show an instability with large displacement bursts at a critical load ranging from 480 μN to 700 μN. This phenomenon is attributed to a transition of the buckling mode of the SiNLs under indentation. Using a set of finite element models with postbuckling analyses, we analyze the indentation-induced buckling modes and investigate the effects of tip location, contact friction, and substrate deformation on the critical load of mode transition. The results demonstrate a unique approach for the study of nanomaterials and patterned nanostructures via a combination of experiments and modeling.

  15. Thermal diffusion boron doping of single-crystal natural diamond

    Science.gov (United States)

    Seo, Jung-Hun; Wu, Henry; Mikael, Solomon; Mi, Hongyi; Blanchard, James P.; Venkataramanan, Giri; Zhou, Weidong; Gong, Shaoqin; Morgan, Dane; Ma, Zhenqiang

    2016-05-01

    With the best overall electronic and thermal properties, single crystal diamond (SCD) is the extreme wide bandgap material that is expected to revolutionize power electronics and radio-frequency electronics in the future. However, turning SCD into useful semiconductors requires overcoming doping challenges, as conventional substitutional doping techniques, such as thermal diffusion and ion implantation, are not easily applicable to SCD. Here we report a simple and easily accessible doping strategy demonstrating that electrically activated, substitutional doping in SCD without inducing graphitization transition or lattice damage can be readily realized with thermal diffusion at relatively low temperatures by using heavily doped Si nanomembranes as a unique dopant carrying medium. Atomistic simulations elucidate a vacancy exchange boron doping mechanism that occurs at the bonded interface between Si and diamond. We further demonstrate selectively doped high voltage diodes and half-wave rectifier circuits using such doped SCD. Our new doping strategy has established a reachable path toward using SCDs for future high voltage power conversion systems and for other novel diamond based electronic devices. The novel doping mechanism may find its critical use in other wide bandgap semiconductors.

  16. Reduction of precursor decay anomaly in single crystal lithium fluoride

    Science.gov (United States)

    Sano, Yukio

    2000-08-01

    The purpose of this study is to reveal that the precursor decay anomaly in single crystal lithium fluoride is reduced by Sano's decay curve [Y. Sano, J. Appl. Phys. 85, 7616 (1999)], which is much smaller in slope than Asay's decay curve [J. R. Asay, G. R. Fowles, G. E. Duvall, M. H. Miles, and R. F. Tinder, J. Appl. Phys. 43, 2132 (1972)]. To this end, strain, particle, velocity, and stress in a precursor and near the leading edge of the follower changing with time along Sano's decay curve are first analyzed quantitatively. The analysis verified the existence of degenerate contraction waves I and II and a subrarefaction wave R', and the decay process [Y. Sano, J. Appl. Phys. 77, 3746 (1995)] caused in sequence by evolving followers C, I, II, R', Rb. Next, inequalities relating decay rates qualitatively to plastic strain rates at the leading edge of the follower, which are derived using the properties of the followers, are incorporated into the analysis. Calculation results showed that the plastic strain rates were reduced by low decay rates. This indicates that the precursor decay anomaly might be greatly reduced by Sano's decay curve.

  17. Triangular nanobeam photonic cavities in single crystal diamond

    CERN Document Server

    Bayn, Igal; Salzman, Joseph; Kalish, Rafi

    2011-01-01

    Diamond photonics provides an attractive architecture to explore room temperature cavity quantum electrodynamics and to realize scalable multi-qubit computing. Here we review the present state of diamond photonic technology. The design, fabrication and characterization of a novel triangular cross section nanobeam cavity produced in a single crystal diamond is demonstrated. The present cavity design, based on a triangular cross section allows vertical confinement and better signal collection efficiency than that of slab-based nanocavities, and eliminates the need for a pre-existing membrane. The nanobeam is fabricated by Focused-Ion-Beam (FIB) patterning. The cavity is characterized by a confocal photoluminescence. The modes display quality factors of Q ~220 and are deviated in wavelength by only ~1.7nm from the NV- color center zero phonon line (ZPL). The measured results are found in good agreement with 3D Finite-Difference-Time-Domain (FDTD) calculations. A more advanced cavity design with Q=22,000 is model...

  18. Ultraviolet Laser-induced ignition of RDX single crystal

    Science.gov (United States)

    Yan, Zhonghua; Zhang, Chuanchao; Liu, Wei; Li, Jinshan; Huang, Ming; Wang, Xuming; Zhou, Guorui; Tan, Bisheng; Yang, Zongwei; Li, Zhijie; Li, Li; Yan, Hongwei; Yuan, Xiaodong; Zu, Xiaotao

    2016-02-01

    The RDX single crystals are ignited by ultraviolet laser (355 nm, 6.4 ns) pulses. The laser-induced damage morphology consisted of two distinct regions: a core region of layered fracture and a peripheral region of stripped material surrounding the core. As laser fluence increases, the area of the whole crack region increases all the way, while both the area and depth of the core region increase firstly, and then stay stable over the laser fluence of 12 J/cm2. The experimental details indicate the dynamics during laser ignition process. Plasma fireball of high temperature and pressure occurs firstly, followed by the micro-explosions on the (210) surface, and finally shock waves propagate through the materials to further strip materials outside and yield in-depth cracks in larger surrounding region. The plasma fireball evolves from isotropic to anisotropic under higher laser fluence resulting in the damage expansion only in lateral direction while maintaining the fixed depth. The primary insights into the interaction dynamics between laser and energetic materials can help developing the superior laser ignition technique.

  19. Unusual magnetotransport properties in a FeAs single crystal

    Science.gov (United States)

    Khim, Seunghyun; Gillig, Matthias; Klingeler, Rüdiger; Wurmehl, Sabine; Büchner, Bernd; Hess, Christian

    2016-05-01

    We have investigated the magnetoresistance (MR) and Hall resistivity properties of a FeAs single crystal which exhibits magnetic order below TN = 69 K. We observe nonlinear Hall resistivity and linear MR in the presence of magnetic-order-connected Fermi surface reconstruction. The analysis of the magnetotransport data using a two-carrier model suggests the emergence of an additional minor hole Fermi surface which coexists with major electron carriers below TN. The origin of the linear MR, however, remains inconsistent with current explanations based on the electronic band structure, i.e., the quantum linear MR model from linearly dispersive Dirac cones and linear MR as a result from strong velocity changes of the cyclotron motion near nested Fermi surfaces. While a macroscopic inhomogeneity in a mobility distribution may cause the linear MR as widely observed in other semimetals with high mobilities, the spiral magnetic order of FeAs seems to ask for an alternative description which takes the specific magnetic order and details of the electronic structure of FeAs as well as a possible entanglement between them into account.

  20. Single crystal CVD diamond membranes for betavoltaic cells

    Science.gov (United States)

    Delfaure, C.; Pomorski, M.; de Sanoit, J.; Bergonzo, P.; Saada, S.

    2016-06-01

    A single crystal diamond large area thin membrane was assembled as a p-doped/Intrinsic/Metal (PIM) structure and used in a betavoltaic configuration. When tested with a 20 keV electron beam from a high resolution scanning electron microscope, we measured an open circuit voltage (Voc) of 1.85 V, a charge collection efficiency (CCE) of 98%, a fill-factor of 80%, and a total conversion efficiency of 9.4%. These parameters are inherently linked to the diamond membrane PIM structure that allows full device depletion even at 0 V and are among the highest reported up to now for any other material tested for betavoltaic devices. It enables to drive a high short-circuit current Isc up to 7.12 μA, to reach a maximum power Pmax of 10.48 μW, a remarkable value demonstrating the high-benefit of diamond for the realization of long-life radioisotope based micro-batteries.

  1. Understanding surface structure and chemistry of single crystal lanthanum aluminate

    KAUST Repository

    Pramana, Stevin S.

    2017-03-02

    The surface crystallography and chemistry of a LaAlO3 single crystal, a material mainly used as a substrate to deposit technologically important thin films (e.g. for superconducting and magnetic devices), was analysed using surface X-ray diffraction and low energy ion scattering spectroscopy. The surface was determined to be terminated by Al-O species, and was significantly different from the idealised bulk structure. Termination reversal was not observed at higher temperature (600 °C) and chamber pressure of 10−10 Torr, but rather an increased Al-O occupancy occurred, which was accompanied by a larger outwards relaxation of Al from the bulk positions. Changing the oxygen pressure to 10−6 Torr enriched the Al site occupancy fraction at the outermost surface from 0.245(10) to 0.325(9). In contrast the LaO, which is located at the next sub-surface atomic layer, showed no chemical enrichment and the structural relaxation was lower than for the top AlO2 layer. Knowledge of the surface structure will aid the understanding of how and which type of interface will be formed when LaAlO3 is used as a substrate as a function of temperature and pressure, and so lead to improved design of device structures.

  2. Recrystallization of Single Crystal Nickel-Based Superalloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bing; TAO Chun-hu; LU Xin; LIU Chang-kui; HU Chun-yan; BAI Ming-yuan

    2009-01-01

    A series of experiments of investigating the recrystallization of single crystal DD3 superalloy were carried out. The threshold temperature for recrystallization and the effect of annealing temperature on recrystaUization were studied. The results show that the threshold temperature for recrystallization of the shot-peened DD3 samples is be-tween 1 000 ℃ and 1 050℃ under the condition of annealing for 2 h, and the recrystallization depth increases with the rise of the annealing temperature. Below 1 150 ℃, the recrystallization depth increases slowly with the tempera-ture climbing, while above 1 150 ℃, the recrystallization depth increases quickly with the rise of the temperature. The solution of the γ' phase is a critical factor of the recrystallization behavior of DD3 superalloy. In addition, the ki-netics and microstructural evolution of recrystallization at 1 200 ℃ were also studied. It is found that the recrystalli-zation progresses rapidly at 1 200℃ through the growth of fully developed recrystallized grains, and the recrystalli-zation process on the shot-peened surface is similar to that of wrought materials, including nucleation of reerystalliza-tion, growth of new grains into the matrix, and growth of new grains by swallowing up each other.

  3. Flux dependence of deuterium retention in single crystal tungsten

    CERN Document Server

    Poon, M; Davis, J W; Haasz, A A

    2002-01-01

    The retention of deuterium in single crystal tungsten has been measured as a function of the incident ion flux in the range of 1x10 sup 1 sup 7 -5x10 sup 1 sup 9 D sup + /m sup 2 s at 300 K. Incident D sub 3 sup + ions were implanted to fluences of 10 sup 2 sup 1 , 10 sup 2 sup 2 , and 10 sup 2 sup 3 D sup + /m sup 2 with ion energies (500 eV/D sup +) below the threshold energy for elastic collision damage. Above 3x10 sup 1 sup 8 D sup + /m sup 2 s, little or no flux dependence is seen. However, a rapid decrease in retention is seen for incident fluxes below 10 sup 1 sup 8 D sup + /m sup 2 s at the 10 sup 2 sup 1 D sup + /m sup 2 fluence, suggesting a threshold value below which retention is strongly reduced. Flux dependence at the higher fluences show a smaller decrease in retention with decreasing flux. The observed results are consistent with trapping and trap evolution by cluster and cavity formation. The effect of specimen surface preparation has proved to be very significant, especially for the lower fl...

  4. Study of growth of single crystal ribbon in space

    Science.gov (United States)

    Wood, V. E.; Markworth, A. J.

    1975-01-01

    The technical feasibility is studied of growing single-crystal silicon ribbon in the space environment. Procedures are described for calculating the electromagnetic fields produced in a silicon ribbon by an rf shaping coil. The forces on the ribbon and the degree of shaping to be expected are determined. The expected steady-state temperature distribution in the ribbon is calculated in the one-dimensional approximation. Calculations on simplified models indicate, that lack of flatness of the shaped ribbon and excessive heating of the melt by the eddy currents induced by the shaping fields may pose problems. An analysis of the relative effects of various kinds of forces other than electromagnetic showed that in the space environment capillarity forces would dominate, and that the shape of the melt is thus principally determined by the shape of any solids with which it comes in contact. This suggests that ribbon may be produced simply by drawing between parallel wires. A concept is developed for a process of off-angle growth, in which the ribbon is pulled at an angle to the solidification front. Such a process promises to offer increased growth rate, better homogeneity, and thinner ribbon.

  5. On plastic flow in notched hexagonal close packed single crystals

    Science.gov (United States)

    Selvarajou, Balaji; Kondori, Babak; Benzerga, A. Amine; Joshi, Shailendra P.

    2016-09-01

    The micromechanics of anisotropic plastic flow by combined slip and twinning is investigated computationally in single crystal notched specimens. Constitutive relations for hexagonal close packed materials are used which take into account elastic anisotropy, thirty potential deformation systems, various hardening mechanisms and rate-sensitivity. The specimens are loaded perpendicular to the c-axis but the presence of a notch generates three-dimensional triaxial stress states. The study is motivated by recent experiments on a polycrystalline magnesium alloy. To enable comparisons with these where appropriate, three sets of activation thresholds for the various deformation systems are used. For the conditions that most closely mimic the alloy material, attention is focused on the relative roles of pyramidal and prismatic slip, as well as on the emergence of {1012bar}[101bar1] extension twinning at sufficiently high triaxiality. In all cases, the spatial variations of stress triaxiality and plastic strain, inclusive of various system activities, are quantified along with their evolution upon straining. The implications of these findings in fundamental understanding of ductile failure of HCP alloys in general and Mg alloys in particular are discussed.

  6. Sensitive X-ray detectors made of methylammonium lead tribromide perovskite single crystals

    NARCIS (Netherlands)

    Wei, Haotong; Fang, Yanjun; Mulligan, Padhraic; Chuirazzi, William; Fang, Hong-Hua; Wang, Congcong; Ecker, Benjamin R.; Gao, Yongli; Loi, Maria Antonietta; Cao, Lei; Huang, Jinsong

    2016-01-01

    The large mobilities and carrier lifetimes of hybrid perovskite single crystals and the high atomic numbers of Pb, I and Br make them ideal for X-ray and gamma-ray detection. Here, we report a sensitive X-ray detector made of methylammonium lead bromide perovskite single crystals. A record-high mobi

  7. Sensitive X-ray detectors made of methylammonium lead tribromide perovskite single crystals

    NARCIS (Netherlands)

    Wei, Haotong; Fang, Yanjun; Mulligan, Padhraic; Chuirazzi, William; Fang, Hong-Hua; Wang, Congcong; Ecker, Benjamin R.; Gao, Yongli; Loi, Maria Antonietta; Cao, Lei; Huang, Jinsong

    2016-01-01

    The large mobilities and carrier lifetimes of hybrid perovskite single crystals and the high atomic numbers of Pb, I and Br make them ideal for X-ray and gamma-ray detection. Here, we report a sensitive X-ray detector made of methylammonium lead bromide perovskite single crystals. A record-high mobi

  8. Lateral-Structure Single-Crystal Hybrid Perovskite Solar Cells via Piezoelectric Poling.

    Science.gov (United States)

    Dong, Qingfeng; Song, Jingfeng; Fang, Yanjun; Shao, Yuchuan; Ducharme, Stephen; Huang, Jinsong

    2016-04-13

    Single-crystal perovskite solar cells with a lateral structure yield an efficiency enhancement 44-fold that of polycrystalline thin films, due to the much longer carrier diffusion length. A piezoelectric effect observed in perovskite single-crystal and the strain-generated grain-boundaries enable ion migration to form a p-i-n structure.

  9. Growth and characterization of pure and doped NLO L-arginine acetate single crystals

    Indian Academy of Sciences (India)

    P Praveen Kumar; V Manivannan; P Sagayaraj; J Madhavan

    2009-08-01

    Single crystals of pure, Cu2+ and Mg2+ doped L-arginine acetate (LAA) were grown successfully by slow evaporation technique. In order to improve the device characteristics of LAA crystals, metal dopants of Cu2+ and Mg2+ were incorporated into the parent crystals. The grown pure and doped crystals were confirmed by X-ray powder diffraction studies. The pure and doped crystals were characterized by Fourier transform Raman (FT–Raman) and thermal studies. Absorptions of these grown crystals were analysed using UV–Vis–NIR studies, and it was found that these crystals possess minimum absorption in the entire visible region. Nonlinear optical studies of pure and doped crystals were carried out and it reveals that the dopants have increased the efficiency of LAA crystals.

  10. The growth of Ho:YAG single crystals by Czochralski method and investigating the formed cores

    Energy Technology Data Exchange (ETDEWEB)

    Hasani Barbaran, J., E-mail: jhasani@aeoi.org.ir; Ghani Aragi, M. R.; Javaheri, I.; Baharvand, B.; Tabasi, M.; Layegh Ahan, R.; Jangjo, E. [NSTRI, Laser and Optics Research School (Iran, Islamic Republic of)

    2015-12-15

    Ho:YAG single crystals were grown by Czochralski technique, and investigated by the X-ray diffraction (XRD) and optical methods. The crystals were cut and polished in order to observe and analyze their cores. It was found that the deviation of the cores formed in the Czochralski grown Ho:YAG single crystals are resulted from non-symmetrical status of thermal insulation around the Iridium crucible.

  11. Growth of lithium triborate single crystals from molten salt solution under various temperature gradients

    Science.gov (United States)

    Guretskii, S. A.; Ges, A. P.; Zhigunov, D. I.; Ignatenko, A. A.; Kalanda, N. A.; Kurnevich, L. A.; Luginets, A. M.; Milovanov, A. S.; Molchan, P. V.

    1995-12-01

    Single crystals of lithium triborate LiB 3O 5 (LBO) have been grown by the top-seeded solution growth method with B 2O 3 as a solvent using different temperature gradients in the zone of crystallization. Optical and nonlinear optical properties of LBO single crystals have been investigated. The influence of post-growth thermal treatment in oxygen atmosphere on the optical properties has been studied.

  12. Electron Cryomicroscopy of Membrane Proteins: Specimen Preparation for Two-Dimensional Crystals and Single Particles

    OpenAIRE

    Schmidt-Krey, Ingeborg; Rubinstein, John L.

    2010-01-01

    Membrane protein structure and function can be studied by two powerful and highly complementary electron cryomicroscopy (cryo-EM) methods: electron crystallography of two-dimensional (2D) crystals and single particle analysis of detergent-solubilized protein complexes. To obtain the highest-possible resolution data from membrane proteins, whether prepared as 2D crystals or single particles, cryo-EM samples must be vitrified with great care. Grid preparation for cryo-EM of 2D crystals is possi...

  13. Crystal growth of high-quality ZrB 2 single crystals using the floating-zone method

    Science.gov (United States)

    Hori, Kenji; Inoue, Shinji; Isogami, Mineo

    2008-01-01

    High-quality ZrB 2 single crystals with diameters of 13 mm and lengths of 45 mm were grown from boron-rich molten zones (boron 80 mol%), using the RF heated floating-zone method. The (0 0 0 1) single crystals were also grown using seed crystals. Control of temperature gradients on the growing interfaces was performed by arranging ceramic cylinders around the growing crystals and the feed rods. This made it possible to grow high-quality ZrB 2 single crystals free of defects such as lineage structures observed in X-ray topographies of cross-sections. In the central areas (3 mm square) of the grown crystals, the full-widths at half-maximum (FWHM) of the X-ray rocking curve (( 10-1¯0) diffraction) were improved to 24.5-42.4 arc sec compared with the crystals obtained until now. The ZrB 2 obtained seems to be quite suitable for substrates of GaN.

  14. The evolution of machining-induced surface of single-crystal FCC copper via nanoindentation.

    Science.gov (United States)

    Zhang, Lin; Huang, Hu; Zhao, Hongwei; Ma, Zhichao; Yang, Yihan; Hu, Xiaoli

    2013-05-04

    The physical properties of the machining-induced new surface depend on the performance of the initial defect surface and deformed layer in the subsurface of the bulk material. In this paper, three-dimensional molecular dynamics simulations of nanoindentation are preformed on the single-point diamond turning surface of single-crystal copper comparing with that of pristine single-crystal face-centered cubic copper. The simulation results indicate that the nucleation of dislocations in the nanoindentation test on the machining-induced surface and pristine single-crystal copper is different. The dislocation embryos are gradually developed from the sites of homogeneous random nucleation around the indenter in the pristine single-crystal specimen, while the dislocation embryos derived from the vacancy-related defects are distributed in the damage layer of the subsurface beneath the machining-induced surface. The results show that the hardness of the machining-induced surface is softer than that of pristine single-crystal copper. Then, the nanocutting simulations are performed along different crystal orientations on the same crystal surface. It is shown that the crystal orientation directly influences the dislocation formation and distribution of the machining-induced surface. The crystal orientation of nanocutting is further verified to affect both residual defect generations and their propagation directions which are important in assessing the change of mechanical properties, such as hardness and Young's modulus, after nanocutting process.

  15. Modulation of nanotube formation in apatite single crystal via organic molecule incorporation

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Takuya, E-mail: tmatsu@dent.osaka-u.ac.jp [Department of Oromaxillofacial Regeneration, Osaka University, 1-8 Yamada-Oka, Suita 565-0871 (Japan); Uddin, Mohammad Hafiz; An, Sang Hyun [Department of Oromaxillofacial Regeneration, Osaka University, 1-8 Yamada-Oka, Suita 565-0871 (Japan); Arakawa, Kazuto; Taguchi, Eiji [Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki 567-0047 (Japan); Nakahira, Atsushi [Department of Material Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai 599-8531 (Japan); Okazaki, Masayuki [Department of Biomaterials Science, Hiroshima University Faculty of Dentistry, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553 (Japan)

    2011-08-15

    Highlights: {yields} Hydroxyapatite incorporating amino acid was fabricated. {yields} The synthesized crystals showed linearly aligned nano-pores in their structure after their EB irradiation or heating. {yields} Amino acid is considered as an effective porogen for the modulation of internal structure of apatite single crystal. - Abstract: Hydroxyapatite materials are potentially useful for biomedical application, especially as vehicles for functional molecules. Structural control of bulk apatite materials, such as in the fabrication of hollow microspheres or porous structures, has been studied for this purpose. However, control of the internal structure of the source apatite crystal itself is still a challenge. Here, we show that small organic molecules incorporated in apatite crystals act as porogens which control the porous structure of apatite single crystal. The presence of amino acid under apatite synthesis conditions leads to firm bindings and encapsulation of the amino acid in apatite single crystals. Amino acid elimination by heating or electron beam irradiation enhances the pore formation in apatite single crystal. Moreover, incorporation of an acidic amino acid in apatite induces peapod like nanotubes in apatite single crystals. This study suggests the potential of using small organics for nano-structural control of apatite single crystals which would be valuable for enhancing drug loadings or modulating material digestion in vivo.

  16. Epitaxial growth of Fe/Ag single crystal superlattices and their magnetic properties

    Institute of Scientific and Technical Information of China (English)

    Yu Gu; Fei Zeng; Fang Lv; Yuli Cu; Pei-yong Yang; Feng Pan

    2009-01-01

    Single crystal Fe/Ag(001) superlattices with various periodicities were fabricated using ultrahigh vacuum evaporation de-position.It was found that single crystal bcc Fe layers and single crystal fcc Ag layers can epitaxially grow on a single crystal Ag buffer layer alternately,which was deposited on NaCl single crystal chips by ion beam assisted deposition.The magnetic measure-ments of the superlattices reveal an oscillation coupling between ferromagnetism and antiferromagnetism as a function of the Ag layer thickness.The oscillation period,which is 1 nm (5 Ag layers),is in good agreement with the calculated values when the Ag thickness is greater than 1.5 nm.While the thickness of the Ag spacer layer decreases to 1 nm,the oscillation coupling varies from calculations,which can be attributed to the intermixing of the interlayers according to the annealing results.

  17. Single Crystal Substrates for Surface Acoustic Wave Devices.

    Science.gov (United States)

    1981-01-01

    The crystal growth of PbBi 2Nb 209 (PBN) by means of the Czochralski pulling method was initiated durinq this contract. No previous report of the...writing the software for a computer controlled constant-diameter attachment for our Czochralski crystal pullers, (bf a majorexperimental effort on the...controlled constant-diameter attachment for our Czochralski crystal pullers, (b) a major experimental effort on the qrowth of lead potassium niobate

  18. Magnetic Relaxation Study on Single Crystals of Ni4 Single-Molecule Magnets

    Institute of Scientific and Technical Information of China (English)

    LI Yan-Rong; LIU Hai-Qing; LIU Ying; SU Shao-Kui; WANG Yun-Ping

    2009-01-01

    The ac susceptibility of single crystals of Nia single-molecule magnets is measured by a compensation measurement setup. The magnetic relaxation time calculated from the peak of the out-phase component of the susceptibility fits the Arrhenius law well and gives an effective spin-flipping energy barrier of Ueff = 7.2 K. This value is far below the classical activation energy barrier of U = 14 K, whereas it is close to the energy gap between the Sz = ±4 and Sz = ±3 doublets, which indicates that quantum tunneling between the Sz = 3 and Sz = -3 states plays a key role in the magnetic relaxation. Therefore the relaxation process combines thermal activation and quantum tunneling. Also we deduce that the blocking temperature of Ni4 single-molecule magnets is lower than 0.3 K by extrapolating the relaxation time plot, which ensures that this single-molecule magnet material enters a long-range magnetic ordered state instead of a spin glass state at 0.91 K.

  19. Effect of crystal shape on neutron rocking curves of perfect single crystals designed for ultra-small-angle scattering experiments

    Science.gov (United States)

    Freund, A. K.; Rehm, C.

    2014-07-01

    The present study has been conducted in the framework of the channel-cut crystal design for the Kookaburra ultra-small-angle neutron scattering (USANS) instrument to be installed at the OPAL reactor of ANSTO. This facility is based on the classical Bonse-Hart method that uses two multiple-reflection crystal systems. The dynamical theory of diffraction by perfect crystals distinguishes two cases: the Darwin case applying to infinitely thick crystals and the Ewald solution for very small absorption taking into account the reflection from the rear face of a plane-parallel crystal reflecting in Bragg geometry. The former is preferable because it yields narrower rocking curves. To prevent the neutrons to "see" the rear face, grooves were machined into the backside of perfect Si test crystals for single reflection and filled with neutron absorbing material. These samples were examined at the S18 instrument of the Institut Laue-Langevin. Unexpectedly the crystals with empty slots showed an increase of the rocking curve width. When filling the slots with an absorber the widths decreased, but without reaching that of the Darwin curve. Understanding the results and achieving a successful crystal design call for the development of a theory that permits to describe neutron diffraction from crystals with a structured back face.

  20. Effect of Metal Dopant on Ninhydrin—Organic Nonlinear Optical Single Crystals

    Directory of Open Access Journals (Sweden)

    R. S. Sreenivasan

    2013-01-01

    Full Text Available In the present work, metal (Cu2+-substituted ninhydrin single crystals were grown by slow evaporation method. The grown crystals have been subjected to single crystal XRD, powder X-ray diffraction, FTIR, dielectric and SHG studies. Single crystal X-ray diffraction analysis reveals that the compound crystallizes in monoclinic system with noncentrosymmetric space group P21 with lattice parameters a=11.28 Å, b=5.98 Å, c=5.71 Å, α=90∘, β=98.57, γ=90∘, and V=381 (Å3, which agrees very well with the reported value. The sharp and strong peaks in the powder X-ray diffraction pattern confirm the good crystallinity of the grown crystals. The presence of dopants marginally altered the lattice parameters without affecting the basic structure of the crystal. The UV-Vis transmittance spectrum shows that the crystal has a good optical transmittance in the entire visible region with lower cutoff wavelength 314 nm. The vibrational frequencies of various functional groups in the crystals have been derived from FT-IR analysis. Based on the shifts in the vibrations, the presence of copper in the lattice of the grown crystal is clearly established from the pure ninhydrin crystals. Both dielectric constant and dielectric loss decrease with the increase in frequency. The second harmonic generation efficiency was measured by employing powder Kurtz method.

  1. Physicochemical, electrical and optical studies of methyl-3-(2-furylmethylidene) carbazate single crystal

    Indian Academy of Sciences (India)

    G Gomathi; R Gopalakrishnan

    2015-09-01

    The current study provides an insight into the physicochemical properties of an organic single crystal methyl-3-(2-furylmethylidene) carbazate, which was grown by employing the slow evaporation solution growth technique and its results were correlated for application point of view. The grown crystal was confirmed by performing single-crystal X-ray diffraction studies and Fourier transform infrared analysis. The optical, thermal, dielectric and mechanical properties of the grown single crystal were primarily investigated. Etching study was performed to analyse the defects and growth mechanism. Kurtz–Perry powder technique was used to study the second harmonic generation efficiency of the crystal and the crystal was found to exhibit Type-I phase matching.

  2. Method for the growth of large low-defect single crystals

    Science.gov (United States)

    Powell, J. Anthony (Inventor); Neudeck, Philip G. (Inventor); Trunek, Andrew J. (Inventor); Spry, David J. (Inventor)

    2008-01-01

    A method and the benefits resulting from the product thereof are disclosed for the growth of large, low-defect single-crystals of tetrahedrally-bonded crystal materials. The process utilizes a uniquely designed crystal shape whereby the direction of rapid growth is parallel to a preferred crystal direction. By establishing several regions of growth, a large single crystal that is largely defect-free can be grown at high growth rates. This process is particularly suitable for producing products for wide-bandgap semiconductors, such as SiC, GaN, AlN, and diamond. Large low-defect single crystals of these semiconductors enable greatly enhanced performance and reliability for applications involving high power, high voltage, and/or high temperature operating conditions.

  3. Growth and studies of cyclohexylammonium 4-methoxy benzoate single crystal for nonlinear optical applications

    Science.gov (United States)

    Sathya, P.; Gopalakrishnan, R.

    2015-06-01

    Cyclohexylammonium 4-Methoxy Benzoate (C4MB) was synthesised and the functional groups were confirmed by FTIR analysis. The purified C4MB (by repeated recrystallisation) was used for single crystal growth. Single crystal of cyclohexylammonium 4-methoxy benzoate was successfully grown by slow evaporation solution growth method at ambient temperature. Structural orientations were determined from single crystal X-ray diffractometer. Optical absorption and cut off wavelength were identified by UV-Visible spectroscopy. Thermal stability of the crystal was studied from thermogravimetric and differential thermal analyses curves. Mechanical stability of the grown crystal was analysed by Vicker's microhardness tester. The Second Harmonic Generation (SHG) study revealed that the C4MB compound exhibits the SHG efficiency 3.3 times greater than KDP crystal.

  4. Growth and studies of cyclohexylammonium 4-methoxy benzoate single crystal for nonlinear optical applications

    Energy Technology Data Exchange (ETDEWEB)

    Sathya, P.; Gopalakrishnan, R., E-mail: krgkrishnan@annauniv.edu [Crystal Research Lab, Department of Physics, Anna University, Chennai-600002 (India)

    2015-06-24

    Cyclohexylammonium 4-Methoxy Benzoate (C4MB) was synthesised and the functional groups were confirmed by FTIR analysis. The purified C4MB (by repeated recrystallisation) was used for single crystal growth. Single crystal of cyclohexylammonium 4-methoxy benzoate was successfully grown by slow evaporation solution growth method at ambient temperature. Structural orientations were determined from single crystal X-ray diffractometer. Optical absorption and cut off wavelength were identified by UV-Visible spectroscopy. Thermal stability of the crystal was studied from thermogravimetric and differential thermal analyses curves. Mechanical stability of the grown crystal was analysed by Vicker’s microhardness tester. The Second Harmonic Generation (SHG) study revealed that the C4MB compound exhibits the SHG efficiency 3.3 times greater than KDP crystal.

  5. Single-Crystal Sapphire Optical Fiber Sensor Instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Pickrell, Gary [Virginia Polytechnic Inst. & State Univ., Blacksburg, VA (United States); Scott, Brian [Virginia Polytechnic Inst. & State Univ., Blacksburg, VA (United States); Wang, Anbo [Virginia Polytechnic Inst. & State Univ., Blacksburg, VA (United States); Yu, Zhihao [Virginia Polytechnic Inst. & State Univ., Blacksburg, VA (United States)

    2013-12-31

    This report summarizes technical progress on the program “Single-Crystal Sapphire Optical Fiber Sensor Instrumentation,” funded by the National Energy Technology Laboratory 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. This project was completed in three phases, each with a separate focus. Phase I of the program, from October 1999 to April 2002, was devoted to development of sensing schema for use in high temperature, harsh environments. Different sensing designs were proposed and tested in the laboratory. Phase II of the program, from April 2002 to April 2009, focused on bringing the sensor technologies, which had already been successfully demonstrated in the laboratory, to a level where the sensors could be deployed in harsh industrial environments and eventually become commercially viable through a series of field tests. Also, a new sensing scheme was developed and tested with numerous advantages over all previous ones in Phase II. Phase III of the program, September 2009 to December 2013, focused on development of the new sensing scheme for field testing in conjunction with materials engineering of the improved sensor packaging lifetimes. In Phase I, three different sensing principles were studied: sapphire air-gap extrinsic Fabry-Perot sensors; intensity-based polarimetric sensors; and broadband polarimetric sensors. Black body radiation tests and corrosion tests were also performed in this phase. 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. At the beginning of Phase II, in June 2004, the BPDI sensor was tested at the Wabash River coal gasifier

  6. Bonding Energy and Growth Habit of Lithium Niobate Single Crystals

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    On the basis of crystallographic structure of lithium niobate (LN), the bonding energy was quantitatively calculated by the bond valence sum model, which was employed to investigate the crystal growth. A possible relationship between the crystal growth habit and chemical bonding energy of LN crystals are found. It is found that the higher the bond energy, the slower the growth rate, and the more important the plane. The analytical results indicate that (012) plane is the most influential face for the LN crystal growth, which consists well with the standard card (JCPDS Card: 20-0631) and our previous experimental observation. The current work shows that the chemical bond analysis of LN crystals allows us to predict its growth habit and thus to obtain the expected morphology during the spontaneous growth.

  7. Covalently Bound Monomolecular Layers on Si Single Crystals

    Science.gov (United States)

    Chidsey, Christopher E. D.

    1996-03-01

    Methods and reagents borrowed from the molecular synthetic chemistry of silicon compounds have been used to form covalently bound monomolecular layers on silicon single crystals. Organic monolayers bound covalently to silicon could form the basis for silicon/organic interfaces useful in sensor structures. In a representative reaction, alkyl monolayers with densities approaching that of crystalline polyethylene have been prepared by the radical-initiated insertion of 1-alkenes into the Si-H bonds of hydrogen-terminated Si(111) surfaces footnote M. R. Linford, P. Fenter, P. M. Eisenberger and C. E. D Chidsey, J. Am. Chem. Soc. 117, 3145-3155 (1995). It has recently been found that this insertion reaction can also be initiated by illumination with UV light having sufficient energy to break the Si-H bond. Synchrotron-based high-resolution photoelectron spectroscopy and diffraction have demonstrated the expected Si-C bond in such monolayers footnote J. H. Terry, R. Cao, P. A. Pianetta, M. R. Linford and C. E. D. Chidsey, unpublished results. An alternate approach to similar monolayers has been found to be the chlorination of hydrogen-terminated Si(111) with Cl_2, followed by the nucleophilic displacement of chlorine with alkyl lithium reagents. The well-behaved chemical transformations of the hydrogen-terminated silicon surfaces appear to result from the essentially bulk termination of the silicon lattice with closed-shell silicon hydride "functional groups" on the surface. In addition to the formation of novel organic layers, a full understanding of the reactivity of the hydrogen-terminated silicon surfaces should lead to better control of key technological silicon interfaces such as Si/SiO_2, Si/epi-Si, and Si/metal.

  8. Compositional Effects on Nickel-Base Superalloy Single Crystal Microstructures

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Garg,Anita; Rogers, Richard B.; Nathal, Michael V.

    2012-01-01

    Fourteen nickel-base superalloy single crystals containing 0 to 5 wt% chromium (Cr), 0 to 11 wt% cobalt (Co), 6 to 12 wt% molybdenum (Mo), 0 to 4 wt% rhenium (Re), and fixed amounts of aluminum (Al) and tantalum (Ta) were examined to determine the effect of bulk composition on basic microstructural parameters, including gamma' solvus, gamma' volume fraction, volume fraction of topologically close-packed (TCP) phases, phase chemistries, and gamma - gamma'. lattice mismatch. Regression models were developed to describe the influence of bulk alloy composition on the microstructural parameters and were compared to predictions by a commercially available software tool that used computational thermodynamics. Co produced the largest change in gamma' solvus over the wide compositional range used in this study, and Mo produced the largest effect on the gamma lattice parameter and the gamma - gamma' lattice mismatch over its compositional range, although Re had a very potent influence on all microstructural parameters investigated. Changing the Cr, Co, Mo, and Re contents in the bulk alloy had a significant impact on their concentrations in the gamma matrix and, to a smaller extent, in the gamma' phase. The gamma phase chemistries exhibited strong temperature dependencies that were influenced by the gamma and gamma' volume fractions. A computational thermodynamic modeling tool significantly underpredicted gamma' solvus temperatures and grossly overpredicted the amount of TCP phase at 982 C. Furthermore, the predictions by the software tool for the gamma - gamma' lattice mismatch were typically of the wrong sign and magnitude, but predictions could be improved if TCP formation was suspended within the software program. However, the statistical regression models provided excellent estimations of the microstructural parameters based on bulk alloy composition, thereby demonstrating their usefulness.

  9. Crystal growth and characterization of third order nonlinear optical piperazinium bis(4-hydroxybenzenesulphonate) (P4HBS) single crystal

    Science.gov (United States)

    Pichan, Karuppasamy; Muthu, Senthil Pandian; Perumalsamy, Ramasamy

    2017-09-01

    The organic single crystal of piperazinium bis(4-hydroxybenzenesulphonate) (P4HBS) was grown by slow evaporation solution technique (SEST) at room temperature. The lattice parameters of the grown crystal were confirmed by single crystal X-ray diffraction analysis. Functional groups of P4HBS crystal were confirmed by FTIR spectrum analysis. The optical quality of the grown crystal was identified by the UV-Vis NIR spectrum analysis. The grown crystal has good optical transmittance in the range of 410-1100 nm. In photoluminescence spectrum, sharp emission peaks are observed, which indicates the ultraviolet (UV) emission. The photoconductivity study reveals that the grown crystal has negative photoconductive nature. The thermal behaviour of the P4HBS crystal was investigated by thermogravimetric and differential thermal analysis (TG-DTA). The mechanical stability of grown crystal was analyzed and the indentation size effect (ISE) was explained by Hays-Kendall's (HK) approach and proportional specimen resistance model (PSRM). Chemical etching study was carried out and the etch pit density (EPD) was calculated. The dielectric constant (ε‧) and dielectric loss (tan δ) as a function of frequency were measured for the grown crystal. The solid state parameters such as valence electron, plasma energy, Penn gap and Fermi energy were evaluated theoretically for the P4HBS using the empirical relation. The estimated values are used to calculate the electronic polarizability. The third-order nonlinear optical properties such as nonlinear refractive index (n2), absorption co-efficient (β) and susceptibility (χ(3)) were studied by Z-scan technique at 632.8 nm using He-Ne laser.

  10. Growth and characterization of new semiorganic nonlinear optical and piezoelectric lithium sulfate monohydrate oxalate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Harsh [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi 110007 (India); Sinha, Nidhi [Department of Physics & Electronics, SGTB Khalsa College, University of Delhi, Delhi 110007 (India); Kumar, Binay, E-mail: b3kumar69@yahoo.co.in [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi 110007 (India)

    2015-04-15

    Highlights: • A new semiorganic single crystal of LSO grown by slow evaporation technique. • Morphological studies of the LSO crystal deduced by BFDH law. • In the UV–vis spectrum wide transparent region and large band gap were found. • SHG is equal to KDP crystal and d{sub 33} was found to be equal to 6pC/N. • Grown crystal belongs to softer category. - Abstract: New semiorganic crystal of lithium sulfate monohydrate oxalate (LSO) for nonlinear application was synthesized by controlled slow evaporation method. The growth rate of various planes of the grown crystal was estimated by morphological study. Single crystal XRD analysis confirmed that the crystal belongs to triclinic lattice with space group P1. High transparency (∼95%) with large band gap (4.57 eV) was analyzed by UV–vis studies. FTIR and Raman spectroscopy were used to identify various functional groups present in the LSO crystal. SHG efficiency was found to be equal to the KDP crystal. Thermal stability (up to 117.54 °C) and melting point (242 °C) of the crystal were studied by TG-DTA. In dielectric measurements, the value of dielectric constant decreases with increase in frequency. Hardness studies confirmed soft nature of crystals. The piezoelectric coefficient was found to be 6pC/N along [0 0 1].

  11. A physically based constitutive model for FCC single crystals with a single state variable per slip system

    Science.gov (United States)

    Demir, Eralp

    2017-01-01

    A new, simple and physically consistent dislocation-density-based continuum model is developed in a large-strain crystal plasticity framework. All the constitutive laws are expressed in a simple and unique way in terms of a single state variable dislocation density. The proposed physically based model predicts experimental single-crystal stress-strain curves along different crystal directions more accurately than a classical model with widely accepted constitutive laws. The polycrystal texture predictions from the dislocation-density-based and classical models having the same single-crystal stress-strain characteristics are in good agreement with the classical model when Taylor-type homogenization is used in conjunction with enough number of grains.

  12. Synthesis, crystal growth and characterization of a phase matchable nonlinear optical single crystal: p-chloro dibenzylideneacetone

    Science.gov (United States)

    Ravindra, H. J.; John Kiran, A.; Nooji, Satheesha Rai; Dharmaprakash, S. M.; Chandrasekharan, K.; Kalluraya, Balakrishna; Rotermund, Fabian

    2008-05-01

    Good quality single crystals of p-chloro dibenzylideneacetone (CDBA) of size 13 mm×8 mm×2 mm were grown by slow evaporation solution growth technique. The grown crystals were confirmed by elemental analysis, Fourier transform infrared (FTIR) analysis and single crystal X-ray diffraction techniques. From the thermo gravimetric/differential thermal (TG/DT) analysis, the CDBA was found to be thermally stable up to 250 °C. The mechanical stability of the crystal is comparable with that of the other reported chalcones. The lower optical cut-off wavelength for this crystal was observed at 440 nm. The laser damage threshold of the crystal was 0.6 GW/cm 2 at 532 nm. The second harmonic generation conversion efficiency of the powder sample of CDBA was found to be 4.5 times greater than that of urea. We also demonstrate the existence of the phase matching property in this crystal using Kurtz powder technique.

  13. Wideband Single-Crystal Transducer for Bone Characterization

    Science.gov (United States)

    Liang, Yu; Snook, Kevin

    2012-01-01

    excitation signal to the transducer and amplifying the signal received from the transducer. The excitation signal may be either a wide-bandwidth signal to excite the transducer across its entire operational spectrum, or a narrow-bandwidth signal optimized for a particular measurement technique. The transducer face is applied to the skin covering the bone to be characterized, and may be operated in through-transmission mode using two transducers, or in pulse-echo mode. The transducer is a unique combination of material, design, and fabrication technique. It is based on single-crystal lead magnesium niobate lead titanate (PMN-PT) piezoelectric material. As compared to the commonly used piezoceramics, this piezocrystal has superior piezoelectric and elastic properties, which results in devices with superior bandwidth, source level, and power requirements. This design necessitates a single resonant frequency. However, by operating in a transverse length-extensional mode, with the electric field applied orthogonally to the extensional direction, resonators of different sizes can share common electrodes, resulting in a multiply-resonant structure. With carefully sized resonators, and the superior bandwidth of piezocrystal, the resonances can be made to overlap to form a smooth, wide-bandwidth characteristic.

  14. Structural, Microhardness, Photoconductivity, and Dielectric Properties of Tris(thiourea Cadmium Sulphate Single Crystals

    Directory of Open Access Journals (Sweden)

    A. P. Arthi

    2014-01-01

    Full Text Available Semiorganic nonlinear optical tris(thiourea cadmium sulphate (TTCS single crystals were grown by slow evaporation method. The crystal system, cell parameter of the grown crystal, was identified by powder X-ray diffraction study. The self-focusing Z-scan technique has been employed to observe the third-order nonlinear optical property of the grown crystal. The mechanical property of the grown crystal was examined by using Vicker’s microhardness test. Chemical etching studies were made on the TTCS crystal using water as an etchant. The dark current and photocurrent properties of the crystal were estimated by using photoconductivity study. The dielectric constant of grown crystal was studied in different temperature by varying applied frequencies.

  15. Growth and characterization of air annealing Mn-doped YAG:Ce single crystal for LED

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Weidong, E-mail: xiangweidong001@126.com [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325035 (China); College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Zhong, Jiasong [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325035 (China); College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Zhao, Yinsheng [Pan Asia Technical Automotive Center Co. Ltd., Shanghai 201201 (China); Zhao, Binyu [College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Liang, Xiaojuan [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325035 (China); Dong, Yongjun [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800 (China); Zhang, Zhimin; Chen, Zhaoping; Liu, Bingfeng [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325035 (China)

    2012-11-25

    Highlights: Black-Right-Pointing-Pointer The YAG:Ce,Mn single crystal was well synthesized by the Czochralski (CZ) method. Black-Right-Pointing-Pointer The emission intensity of the sample has been influenced after annealing. Black-Right-Pointing-Pointer Annealed in the air at 1200 Degree-Sign C was the most optimal annealing condition. Black-Right-Pointing-Pointer The single crystal could be used in the white light LED which emitted by blue light. - Abstract: The growth of Mn-doped YAG:Ce (yttrium aluminum garnet doped cerium) single crystal by the Czochralski (CZ) method and the characterization of its spectroscopy and color-electric parameters are presented. The absorption spectra indicate that the crystal absorbed highly in the 300-500 nm wavelength range. The emission spectrum of the crystal consists of a peak around 538 nm when excited by 460 nm blue light, which prove the YAG:Ce,Mn single crystal could be used in the white light emitting doides (LED). The different charges of Mn ions have different luminescence properties, and the air annealing process for the single crystal would change the concentration of Mn ions with different charges, which could influence the emission intensity of the single crystal.

  16. Application of ZnO single crystals for light-induced water splitting under UV irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Suhak, Yuriy, E-mail: suhak@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Izdebska, Katarzyna; Skupiński, Paweł; Wierzbicka, Aleksandra; Reszka, Anna; Sybilski, Piotr; Kowalski, Bogdan J.; Mycielski, Andrzej; Zytkiewicz, Zbigniew R. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Soszko, Michał [Industrial Chemistry Research Institute, Rydygiera 8, 01-793 Warsaw (Poland); Suchocki, Andrzej [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Institute of Physics, University of Bydgoszcz, Weyssenhoffa 11, 85-072 Bydgoszcz (Poland)

    2014-02-14

    This paper presents experimental results of implementation of ZnO single crystals as photoanodes in photoelectrochemical (PEC) cells for hydrogen generation through the process of water splitting. Both, as-grown and O{sub 2}-annealed ZnO single crystals were investigated for this purpose. A 351 nm argon laser line was used as the light source. The XRD investigations showed that used ZnO crystals are of good crystalline quality. It was found that the as-grown ZnO single crystals possess higher conversion efficiencies comparing to the O{sub 2}-annealed one. The photocurrent density was found to increase significantly with the increase of external bias applied and excitation light intensity. Time dependent photocurrent density characteristics showed that the decay of photocurrent density was not observed within the measurement time. The differences in behaviour of the as-grown and the annealed in O{sub 2} ZnO single crystals are discussed in terms of crystals intrinsic defects. - Highlights: • ZnO single crystals show excellent performance as photoanodes for water splitting. • ZnO single crystals showed good stability in aqueous solution. • Mid-gap band state introduction does not influence the efficiency of water splitting.

  17. Pyroelectric properties and electrocaloric effect in TGS1-xPx single crystals

    Science.gov (United States)

    Sampathkumar, P.; Srinivasan, K.

    2016-10-01

    Triglycine sulfate (TGS) single crystals modified with phosphoric acid (TGS1-xPx) have been grown by slow evaporation technique at room temperature. Lattice parameters were identified by using single crystal x-ray diffractometer. The dielectric, pyroelectric, ferroelectric properties and electrocaloric effect have been investigated. Curie temperature of grown crystals was determined from dielectric constant measurements at various temperatures at a frequency of 1 kHz. The Curie temperature is found decreased for the TGS single crystals with the addition of phosphoric acid. Room temperature P-E hysteresis loops of TGS1-xPx single crystals are presented. The values of coercive field Ec, spontaneous polarization Ps and internal bias field Eb were obtained from the hysteresis loops. Discussion on pyroelectric properties as a function of temperature and applied electric field is presented. Figure of merits (FOMs) were determined to study the pyroelectric performance of the grown crystals. Among all compositions of x, x = 0.2 (i.e., TGS0.8P0.2) single crystals exhibited the largest pyroelectric coefficient and pyroelectric figure of merit at room temperature. From the above investigations the electrocaloric temperature change, ΔT of TGS1-xPx single crystals at selected applied fields and temperatures are obtained by indirect method and discussed.

  18. Mechanism of the superior mechanical strength of nanometer-sized metal single crystals revealed

    KAUST Repository

    Afify, N. D.

    2013-10-01

    Clear understanding of the superior mechanical strength of nanometer-sized metal single crystals is required to derive advanced mechanical components retaining such superiority. Although high quality studies have been reported on nano-crystalline metals, the superiority of small single crystals has neither been fundamentally explained nor quantified to this date. Here we present a molecular dynamics study of aluminum single crystals in the size range from 4.1 nm to 40.5 nm. We show that the ultimate mechanical strength deteriorates exponentially as the single crystal size increases. The small crystals superiority is explained by their ability to continuously form vacancies and to recover them. © 2013 Published by Elsevier B.V.

  19. A 3D MOF showing unprecedented solvent-induced single-crystal-to-single-crystal transformation and excellent CO2 adsorption selectivity at room temperature.

    Science.gov (United States)

    Qin, Tao; Gong, Jun; Ma, Junhan; Wang, Xin; Wang, Yonghua; Xu, Yan; Shen, Xuan; Zhu, Dunru

    2014-12-28

    A water stable porous 3D metal-organic framework, [Cu3L2(μ3-OH)2(μ2-H2O)]·2DMA (1, mother crystal, H2L = 2,2'-dinitrobiphenyl-4,4'-dicarboxylic acid, DMA = N,N-dimethylacetamide), shows unprecedented irreversible solvent-induced substitutions of bridging aqua ligands and guest-exchanges in single-crystal-to-single-crystal (SCSC) transformations at room temperature (RT), producing quantitatively three daughter crystals, [Cu3L2(μ3-OH)2]·2S (2: 2A, S = acetone; 2B, S = 2-propanol; 2C, S = 2-butanol), which exhibit reversible interconversion by guest-exchanges at RT in SCSC transformations. MOF 1 shows excellent separation selectivity (128) of CO2/N2 at RT and is a better sorbent of micro-solid-phase extraction (μ-SPE) than currently known benchmark ZIF-8.

  20. Fabrication of Triangular Nanobeam Waveguide Networks in Bulk diamond Using Single-Crystal Silicon Hard Masks

    CERN Document Server

    Bayn, I; Li, L; Goldstein, J A; Schröder, T; Zhang, J; Chen, E H; Gaathon, O; Lu, M; Stein, A; Ruggiero, C A; Salzman, J; Kalish, R; Englund, D

    2014-01-01

    A scalable approach for integrated photonic networks in single-crystal diamond using triangular etching of bulk samples is presented. We describe designs of high quality factor (Q=2.51x10^6) photonic crystal cavities with low mode volume (Vm=1.062x({\\lambda}/n)^3), which are connected via waveguides supported by suspension structures with predicted transmission loss of only 0.05 dB. We demonstrate the fabrication of these structures using transferred single-crystal silicon hard masks and angular dry etching, yielding photonic crystal cavities in the visible spectrum with measured quality factors in excess of Q=3x103.

  1. Sapphire: Relation between luminescence of starting materials and luminescence of single crystals

    Science.gov (United States)

    Mogilevsky, R.; Nedilko, S.; Sharafutdinova, L.; Burlay, S.; Sherbatskii, V.; Boyko, V.; Mittl, S.

    2009-10-01

    A relation between photoluminescence (PL) characteristics of different starting materials used for crystal growth and un-doped sapphire single crystals manufactured using various methods of crystal growth (Kyropolus, HEM, Czochralski, and EFG) was found. The crystals grown using the Verneuil starting material exhibited significant PL when any method of crystal growth was used. On the contrary, sapphire samples grown by the same technologies wherein the starting material was EMT HPDA R revealed very low PL. (HPDA R is produced by EMT, Inc., with proprietary and patented technology.)

  2. Single crystal PMN-PT/epoxy 1-3 composite for energy-harvesting application.

    Science.gov (United States)

    Ren, Kailiang; Liu, Yiming; Geng, Xuecang; Hofmann, Heath F; Zhang, Qiming M

    2006-03-01

    One key parameter in using electroactive materials to harvest electric energy from mechanical sources is the energy conversion efficiency. Recently, it was shown that, in the relaxor ferroelectric PMN-PT single crystals, a very high longitudinal electromechanical coupling factor (>90%) can be obtained. This paper investigates energy harvesting using 1-3 composites of PMN-PT single crystals in a soft epoxy matrix. It is shown that 1-3 composites enable the single crystals operating in the longitudinal mode to achieve high efficiency for energy harvesting, and the soft-polymer, matrix-supported single-crystal rods maintain high mechanical integrity under different external loads. For comparison, 1-3 composites with piezoceramic PZT also are investigated in energy-harvesting applications, and the results show that the high coupling factor of single crystal PMN-PT 1-3 composites leads to much higher electric energy output for similar mechanical energy input. The harvested energy density of 1-3 composite with single crystal (22.1 mW/cm3 under a stress of 40.4 MPa) is about twice of that harvested with PZT ceramic 1-3 composite (12 mW/cm3 under a stress of 39 MPa). At a higher stress level, the harvested-energy density of 1-3 PMN-PT single crystal composite can reach 96 mW/cm3.

  3. Fluid inclusions and microstructures in experimentally deformed quartz single crystals

    Science.gov (United States)

    Thust, A.; Tarantola, A.; Heilbronner, R.; Stünitz, H.

    2009-04-01

    The "H2O-weakening" effect that reduces the strength of quartz dramatically (e.g. Griggs & Blacic 1965) is still not understood. For example, Kronenberg & Tullis (1984) conclude that the weakening effect is pressure dependent while Paterson (1989) infers a glide and recovery control of water. Obviously, the spatial distribution and transport of H2O are important factors (Kronenberg et al. 1986, FitzGerald et al. 1991). We have carried out experiments on milky quartz in a Griggs deformation apparatus. Cylinders (6.5 mm in diameter, 12-13 mm in length) from a milky zone of a natural quartz single crystal have been cored in orientations (1) normal to one of the prism planes and (2) 45˚ to and 45˚ to (O+orientation). At 1 GPa confining pressure, 900˚ C and 10-6s-1, the flow strength is 150 MPa for samples with orientation (1). Further experiments are needed to establish the flow strength for orientation (2). FTIR measurements on double-polished thick sections (200-500 μm) in the undeformed quartz material yield an average H2O content of approximately 100 H/106Si. The water is heterogeneously distributed in the sample. Direct measurements on fluid inclusions yield a H2O content of more than 25 000 H/106Si. Thus, the H2O in the undeformed material is predominantly present in fluid inclusions of size from tens to hundred microns. Micro-thermometric measurements at low temperature indicate the presence of different salts in the fluid inclusions. The ice melting temperature, between -6.9 and -7.4˚ C, indicate an average salinity of 10.5 wt% NaCl. After deformation the distribution of H2O is more homogeneous throughout the sample. The majority of the big inclusions have disappeared and very small inclusions of several microns to sub-micron size have formed. FTIR measurements in zones of undulatory extinction and shear bands show an average H2O content of approximately 3000 H/106Si. Moreover, the larger fluid inclusions are characterized by a higher salinity (12 wt%) due

  4. Growth and characterization of solution-grown tetra glycine barium chloride (TGBC) single crystals

    Science.gov (United States)

    Senthil Pandian, M.; Ramasamy, P.

    2008-05-01

    The single crystals of tetra glycine barium chloride (TGBC), a semi-organic material, were grown by the solvent evaporation technique from an aqueous solution of glycine and barium chloride at ambient temperature. Good optical quality single crystals of size 11×13×7 mm 3 were grown in a period of 2 weeks. Powder X-ray diffraction (XRD) and Fourier transform infrared transmission (FTIR) have confirmed the formation of the new crystal. The grown crystals were characterized by single-crystal XRD analysis to study the crystal structure. The crystalline perfection was evaluated by high-resolution X-ray diffractometry (HRXRD). From this analysis we found that the quality of the crystal was quite good. The full-width at half-maximum (FWHM) of the diffraction curves is 8.5 arcsec, which is very close to that expected from the plane wave dynamical theory of XRD showing that the crystalline perfection is excellent. UV-Vis-NIR spectrum was recorded to study the optical transparency of the grown crystals. Thermal properties of the crystal have been investigated using thermo gravimetric (TG), differential thermal analysis (DTA). The mechanical strength of the crystal is estimated by Vicker's hardness test.

  5. Crystal growth and transport properties of CuAlO2 single crystal

    Science.gov (United States)

    Brahimi, R.; Rekhila, G.; Trari, M.; Bessekhouad, Y.

    2014-12-01

    The transport properties of the delafossite CuAlO2 single crystal, grown by the flux method, are confined in ∞[AlO2] layers extending in the (001) plans. The dielectric properties are measured up to 490 K in the frequency range (102-105 Hz). The small variation of the dielectric loss tan(δ) is attributed to the wide space charge region. The linear plot log (conductivity) vs. 1000/ T follows an Arrhenius type law and the results are discussed in terms of electron hopping among localized states. The activation energy (0.18 eV) gives an effective mass of 16 m 0 indicating that the levels in the vicinity of the Fermi level are strongly localized. Hence, the increase of the conductivity (σ) results from a thermal activation of the mobility (μ300 K = 1.2 × 10-5 cm-2 V-1 s-1). The sign of hole like small polarons is that of p type carriers originating from oxygen intercalation. The thermopower is little temperature dependent and characteristic of non degenerate conductivity with a low holes concentration and a large concentration of surface states within the gap region.

  6. Single-displacement controlled spontaneous electrolysis towards CuTCNQ microribbon electrodes in organic single-crystal transistors.

    Science.gov (United States)

    He, Liangfu; Ji, Zhuoyu; Zhen, Yonggang; Liu, Jie; Yang, Fangxu; Zhao, Qiang; Dong, Huanli; Hu, Wenping

    2015-10-28

    Using single-displacement controlled spontaneous electrolysis solution-prepared CuTCNQ microribbons as the source/drain electrodes, we have fabricated 9,10-bis(2-phenylethynyl)anthracene (BEPA) based organic single crystal top-contact field-effect transistors. The interfacial energetic match between organic semiconductors and CuTCNQ electrodes with the low contact resistance accounts for the compelling improvement in electrical characteristics relative to the copper electrode, even comparable to gold counterparts. Furthermore, we have estimated the contact resistance of single-crystal transistors by the transfer line method (TLM).

  7. Preparative crystallization of a single chain antibody using an aqueous two-phase system.

    Science.gov (United States)

    Huettmann, Hauke; Berkemeyer, Matthias; Buchinger, Wolfgang; Jungbauer, Alois

    2014-11-01

    A simultaneous crystallization and aqueous two-phase extraction of a single chain antibody was developed, demonstrating process integration. The process conditions were designed to form an aqueous two-phase system, and to favor crystallization, using sodium sulfate and PEG-2000. At sufficiently high concentrations of PEG, a second phase was generated in which the protein crystallization occurred simultaneously. The single chain antibody crystals were partitioned to the top, polyethylene glycol-rich phase. The crystal nucleation took place in the sodium sulfate-rich phase and at the phase boundary, whereas crystal growth was progressing mainly in the polyethylene glycol-rich phase. The crystals in the polyethylene glycol-rich phase grew to a size of >50 µm. Additionally, polyethylene glycol acted as an anti-solvent, thus, it influenced the crystallization yield. A phase diagram with an undersaturation zone, crystallization area, and amorphous precipitation zone was established. Only small differences in polyethylene glycol concentration caused significant shifts of the crystallization yield. An increase of the polyethylene glycol content from 2% (w/v) to 4% (w/v) increased the yield from approximately 63-87%, respectively. Our results show that crystallization in aqueous two-phase systems is an opportunity to foster process integration.

  8. Synthesis and photocatalytic activity of mesoporous - (001) facets TiO2 single crystals

    Science.gov (United States)

    Dong, Yeshuo; Fei, Xuening; Zhou, Yongzhu

    2017-05-01

    In this work, the mesoporous - (001) facets TiO2 single crystals have been successfully synthesized through a two-step solvothermal route without any template. Their structure and morphology were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy and energy dispersive X-ray spectrometer (EDX). Based on the different characteristics and atomic arrangements on each facet of anatase TiO2 single crystals, we synthesized these mesoporous - (001) facets TiO2 single crystals by controlling the interaction characteristics of hydrofluoric acid (HF) and isopropanol (i-PrOH) on the crystal facets. It can been seen that the (001) facets of these as-synthesized TiO2 single crystals have a clear mesoporous structure through the SEM images and BET methods. Moreover, the other four facets were covered by the flower - shaped TiO2 crystals with the generation of the mesoporous - (001) facets. This special and interesting morphology could promote charge separation and provide more active sites, which will lead to a substantial increase in photocatalytic activity. Moreover, it is more intuitive to reflect that the different crystal facets possess the different properties due to their atomic arrangement. Besides, according to the different synthetic routes, we proposed and discussed a plausible synthesis mechanism of these mesoporous - (001) facets TiO2 single crystals.

  9. Abnormal dielectric characteristics of PMN-32% PT single crystal under dc bias

    Institute of Scientific and Technical Information of China (English)

    XI Zengzhe; LI Zhenrong; XU Zhuo; ZHANG Liangying; YAO Xi

    2003-01-01

    The dielectric properties and phase transition behavior of the [001] and [111] oriented PMN-32%PT single crystal under the different dc bias (E) have been investigated as a function of temperatures. Under the application of dc bias ranging from 1.5 to 4.0 kV/cm, the dielectric spectrum of a [001] oriented single crystal showed an abnormal dielectric peak within the rhombic phase-stable temperature range.However, this peak disappeared at E>4.0 kV/cm and was not yet found in the [111] oriented single crystal. The abnormal dielectric peak was attributed to the filed-induced phase transition.

  10. Laser-Aided Direct Writing of Nickel-Based Single-Crystal Super Alloy (N5)

    Science.gov (United States)

    Wang, Yichen; Choi, Jeongyoung; Mazumder, Jyoti

    2016-12-01

    This communication reports direct writing of René N5 nickel-based Super alloy. N5 powder was deposited on (100) single-crystal substrate of René N5, for epitaxial growth, using laser and induction heating with a specially designed closed-loop thermal control system. A thin wall (1 mm width) of René N5 single crystal of 22.1 mm (including 3 mm SX substrate) in height was successfully deposited within 100 layers. SEM and EBSD characterized the single-crystal nature of the deposit.

  11. Compression of Single-Crystal Orthopyroxene to 60GPa

    Science.gov (United States)

    Finkelstein, G. J.; Dera, P. K.; Holl, C. M.; Dorfman, S. M.; Duffy, T. S.

    2010-12-01

    Orthopyroxene ((Mg,Fe)SiO3) is one of the dominant phases in Earth’s upper mantle - it makes up ~20% of the upper mantle by volume. At high pressures and temperatures, this phase undergoes several well-characterized phase transitions. However, when compressed at low temperature and high-pressure, orthopyroxene is predicted to exhibit metastable behavior(1). Previous researchers have found orthoenstatite (Mg endmember of orthopyroxene) persists up to ~10 GPa, and diffraction(2-3), Raman(4), and elasticity(5) experiments suggest a phase transition above this pressure to an as-yet unidentified structure. While earlier diffraction data has surprisingly only been evaluated for structural information to ~9 GPa(2), changes in high-pressure Raman spectra to ~70 GPa indicate that several more high-pressure phase transitions in orthopyroxene are likely, including at least one change in Si-coordination(6). We have recently conducted exploratory experiments to further elucidate the high-pressure behavior of orthopyroxene. Compressing a single crystal of Fe-rich orthopyroxene (Fe0.66Mg0.24Ca0.05SiO3) using a diamond anvil cell, we observe phase transitions at ~10, 14, and 30 GPa, with the new phases having monoclinic, orthorhombic, and orthorhombic symmetries, respectively. While the first two transitions do not show a significant change in volume, the phase transition at ~30 GPa shows a large decrease in volume, which is consistent with a change in Si coordination number to mixed 4- and 6-fold coordination. References: [1] S. Jahn, American Mineralogist 93, 528-532 (2008). [2] R. J. Angel, J. M. Jackson, American Mineralogist 87, 558-561 (2002). [3] R. J. Angel, D. A. Hugh-Jones, Journal of Geophysical Research-Solid Earth 99, 19,777-19,783 (1994). [4] G. Serghiou, Journal of Raman Spectroscopy 34, 587-590 (2003). [5] J. Kung et al., Physics of the Earth and Planetary Interiors 147, 27-44 (2004). [6] G. Serghiou, A. Chopelas, R. Boehler, Journal of Physics: Condensed Matter

  12. Growth and study of some gel grown group II single crystals of iodate

    Indian Academy of Sciences (India)

    Sharda J Shitole; K B Saraf

    2001-10-01

    Single crystals of calcium iodate and barium iodate were grown by simple gel technique by single diffusion method. The optimum conditions were established by varying various parameters such as pH of gel solution, gel concentration, gel setting time, concentration of the reactants etc. Crystals having different morphologies and habits were obtained. Prismatic, dendritic crystals of barium iodate and prismatic, needle shaped, hopper crystals of calcium iodate were obtained. Some of them were transparent, some transluscent, and few others were opaque. Both the crystals were studied using XRD, FT-IR, and thermal analysis. The crystals were doped by iron impurity. The effect of doping was studied using IR spectroscopy and thermal analysis.

  13. SHG Materials Based on the AlPO4-5 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Large AlPO4-5 molecular sieve single crystals with high optical quality were synthesized hydrothermally by using TPA as template. As-synthesized crystals were calcined under O2 atmosphere to remove the organic templates in the channels. Disperse-Red-1 (DR1) and p-nitroaniline (pNA) molecules have been successfully incorporated into the one-dimensional channels of AlPO4-5 single crystals respectively by means of vapor phase diffusion. XRD patterns reveal that the loading of organic molecules has not destroyed the structures of AlPO4-5 crystals. Polarizing microscope and SHG results indicate that the DR1 and pNA molecules are well aligned in a preferred direction along the crystal channels. The different polarization-dependence SH intensity shows that different SHG processes occur in the DR1- and pNA-loaded AlPO4-5 crystals.

  14. Synthesis, growth, optical, mechanical and electrical properties of -lysine -lysinium dichloride nitrate (-LLDN) single crystal

    Indian Academy of Sciences (India)

    V Vasudevan; R Ramesh Babu; A Reicher Nelcy; G Bhagavannarayana; K Ramamurthi

    2011-06-01

    Semi-organic nonlinear optical material, -lysine -lysinium dichloride nitrate (2C6H15N2O$^{+}_{2}$.H+.NO$^{-}_{3}$.2Cl-) was synthesized at room temperature. Single crystals of -LLDN were grown by slow cooling solution growth technique. The grown crystal was confirmed by powder X-ray diffraction analysis. The crystalline perfection of the grown single crystal was characterized by high-resolution X-ray diffraction (HRXRD) studies. The cut-off wavelength was determined by UV-vis transmission spectral analysis. The frequency doubling of the grown crystal was confirmed by powder second harmonic generation (SHG) measurement. The refractive index and birefringence of the crystal were determined using He–Ne laser source. Mechanical property of the crystal was determined by Vickers hardness tester. The frequency and temperature dependence of dielectric constant (r), dielectric loss (tan ) and a.c. conductivity (ac) were also measured.

  15. Growth aspects, structural, optical, thermal and mechanical properties of benzotriazole pyridine-2-carboxylic acid single crystal

    Science.gov (United States)

    Thirunavukkarsu, A.; Sujatha, T.; Umarani, P. R.; Nizam Mohideen, M.; Silambarasan, A.; Kumar, R. Mohan

    2017-02-01

    Benzotriazole pyridine-2-carboxylic acid single crystal (BTPCA) was grown by slow evaporation solution growth technique. The cell parameters and crystallinity of BTPCA crystal were found by single crystal and powder X-ray diffraction studies. The presence of functional groups was studied by FT-IR analysis. UV-vis-NIR transmission studies reveal that the BTPCA crystal is transparent in the entire visible region with lower optical cut-off wavelength of 306 nm. The thermal stability, melting point and decomposition stages of BTPCA were analysed from the thermogravimetric and differential thermal analyses. The second harmonic output power of BTPCA was measured to be 2.5 times that of KDP reference crystal. Hardness studies reveal that grown crystal shows the reverse indentation size effect and breakeven point due to release of internal fatigue generated during indentation.

  16. Single crystal structures of thallium (I) thorium fluorides and crystal chemistry of monovalent tetravalent cation pentafluorides

    Science.gov (United States)

    Oudahmane, Abdelghani; El-Ghozzi, Malika; Jouffret, Laurent; Avignant, Daniel

    2015-12-01

    Two thallium (I) thorium (IV) fluorides, TlTh3F13 and TlThF5 were obtained by solid state synthesis and their crystal structures determined from single crystal X-ray diffraction data recorded at room temperature with an APEX-II CCD diffractometer. TlTh3F13 is orthorhombic, space group Pmc21, with a=8.1801(2) Å, b=7.4479(2) Å, c=8.6375(2) Å, V=526.24(2) Å3, Z=2 and TlThF5 is monoclinic, space group P21/n, with a=8.1128(5) Å, b=7.2250(4) Å, c=8.8493(6) Å, β=116.683(3)°, V=463.46(5) Å3, Z=4. The structure of TlTh3F13 comprises layers of corner and edge-sharing ThF9 polyhedra further linked by chains of trans connected tricapped trigonal prisms ThF9 through corners and edges. The three dimensional thorium frameworks delimits channels parallel to [0 0 1] where the 11-coordinated Tl+ ions are arranged into double columns located in mirror planes of the structure. TlTh3F13 is isotypic with RbTh3F13, RbU3F13 and with one of the two polymorphs of CsTh3F13. The structure of TlThF5 may be regarded as a layer structure built up from the regular succession of 2∞[ M ‧F5 ] - corrugated layers further held by the Tl+ ions along the [1 0 1 ̅] direction. The layers are built up from edge and corner-sharing thorium polyhedra where each (ThF9)5- monocapped square antiprism is connected to five others by sharing three edges and two corners. TlThF5 is isostructural with β-NH4UF5 and with one of the polymorphs of CsThF5. A comparison of the different structural types of MM‧F5 pentafluorides is presented and a diagram of repartition of their structures is given. From the comparison of the Tl structures with their Rb or Cs homologs, where very similar monovalent cation environments are observed it should be concluded to a stereochemically inactivity of the 6s2 lone pair of Tl(I) in both TlTh3F13 and TlThF5, contrary to what is observed in richer Tl(I) content Tl3ThF7 fluorothorate.

  17. Effect of indium and antimony doping in SnS single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chaki, Sunil H., E-mail: sunilchaki@yahoo.co.in; Chaudhary, Mahesh D.; Deshpande, M.P.

    2015-03-15

    Highlights: • Single crystals growth of pure SnS, indium doped SnS and antimony doped SnS by direct vapour transport (DVT) technique. • Doping of In and Sb occurred in SnS single crystals by cation replacement. • The replacement mechanism ascertained by EDAX, XRD and substantiated by Raman spectra analysis. • Dopants concentration affects the optical energy bandgap. • Doping influences electrical transport properties. - Abstract: Single crystals of pure SnS, indium (In) doped SnS and antimony (Sb) doped SnS were grown by direct vapour transport (DVT) technique. Two doping concentrations of 5% and 15% each were employed for both In and Sb dopants. Thus in total five samples were studied viz., pure SnS (S1), 5% In doped SnS (S2), 15% In doped SnS (S3), 5% Sb doped SnS (S4) and 15% Sb doped SnS (S5). The grown single crystal samples were characterized by evaluating their surface microstructure, stoichiometric composition, crystal structure, Raman spectroscopy, optical and electrical transport properties using appropriate techniques. The d.c. electrical resistivity and thermoelectric power variations with temperature showed semiconducting and p-type nature of the as-grown single crystal samples. The room temperature Hall Effect measurements further substantiated the semiconducting and p-type nature of the as-grown single crystal samples. The obtained results are deliberated in detail.

  18. A single-solenoid pulsed-magnet system for single-crystal scattering studies.

    Science.gov (United States)

    Islam, Zahirul; Capatina, Dana; Ruff, Jacob P C; Das, Ritesh K; Trakhtenberg, Emil; Nojiri, Hiroyuki; Narumi, Yasuo; Welp, Ulrich; Canfield, Paul C

    2012-03-01

    We present a pulsed-magnet system that enables x-ray single-crystal diffraction in addition to powder and spectroscopic studies with the magnetic field applied on or close to the scattering plane. The apparatus consists of a single large-bore solenoid, cooled by liquid nitrogen. A second independent closed-cycle cryostat is used for cooling samples near liquid helium temperatures. Pulsed magnetic fields close to ~30 T with a zero-to-peak-field rise time of ~2.9 ms are generated by discharging a 40 kJ capacitor bank into the magnet coil. The unique characteristic of this instrument is the preservation of maximum scattering angle (~23.6°) on the entrance and exit sides of the magnet bore by virtue of a novel double-funnel insert. This instrument will facilitate x-ray diffraction and spectroscopic studies that are impractical, if not impossible, to perform using split-pair and narrow-opening solenoid magnets. Furthermore, it offers a practical solution for preserving optical access in future higher-field pulsed magnets.

  19. Growth, characterization and dielectric property studies of gel grown barium succinate single crystals

    Indian Academy of Sciences (India)

    M P Binitha; P P Pradyumnan

    2014-05-01

    Single crystals of barium succinate (BaC4H4O4) were grown in silica gel medium using controlled chemical reaction method. Plate-like single crystals of size up to 3 × 2 × 0.2 mm3 was obtained. Single crystal X-ray diffraction (XRD) studies confirmed that structure of the title compound is tetragonal. Powder X-ray diffraction (PXRD) pattern of the grown crystal and the Fourier transform infrared (FT–IR) spectrum in the range 400–4000 cm-1 are recorded. The vibrational bands corresponding to different functional groups are assigned. Thermal stability of the grown crystals is confirmed by differential scanning calorimetry (DSC). Dielectric constant and dielectric loss have been calculated and discussed as a function of frequency at different temperatures.

  20. A computer study and photoelectric property analysis of potassium-doped lithium niobate single crystals.

    Science.gov (United States)

    Wang, Wei; Wang, Rui; Zhang, Wen; Xing, Lili; Xu, Yanling; Wu, Xiaohong

    2013-09-14

    First-principles theory was used to design a potassium-doped lithium niobate single crystal. The structural, electronic, optical and ferroelectric properties of the potassium-doped LiNbO3 single crystal model have been investigated using a generalized gradient approximation within density functional theory. It was found that substitution with potassium drastically changed the optical and electronic nature of the crystal and that the band gap slightly decreases. A series of LiNbO3 single crystals doped with x mol% K (x = 0, 3, 6, 9, 12 mol%) were successfully grown using the Czochralski method. The crystals were characterized using powder X-ray diffraction, UV-vis-infrared absorption spectroscopy and a ferroelectric property test. The experimental test results were consistent with the calculated predictions.

  1. Magneto-optic sensor based on electrogyration compensation and single-quartz crystal

    Science.gov (United States)

    Li, Changsheng; Cui, He; Zhang, Xuan

    2016-11-01

    Magnetooptic sensor based on electrogyration compensation is proposed and experimentally demonstrated by using single quartz crystal. The sensing unit is composed of single quartz crystal and two polarizers. Quartz crystal exhibits magneto-optic, electro-optic and electrogyration effects, thus magneto-optic Faraday rotation angle can be compensated by the electrogyration angle induced by the compensating voltage applied to the crystal. The compensating voltage is sensitive to both the deviation angle between light beam and principal crystalline axis, and the azimuth angle of polarizer. The 50Hz ac magnetic flux density within 267Gs has been measured, the compensating voltage is 0.72V/Gs for a single quartz crystal with a length of 23mm. The proposed sensor has potential application to closed-loop measurement of magnetic field.

  2. Growth of large naphthalene and anthracene single-crystal sheets at the liquid–air interface

    Energy Technology Data Exchange (ETDEWEB)

    Postnikov, V. A., E-mail: postva@yandex.ru [Donbas National Academy of Civil Engineering and Architecture (Ukraine); Chertopalov, S. V. [Donetsk National University (Ukraine)

    2015-07-15

    The growth of organic single crystals of naphthalene (C{sub 10}H{sub 8}) and anthracene (C{sub 14}H{sub 10}) at the liquid‒air interface from a mixture of solvents has been investigated. The growth technique used in the study makes it possible to obtain single-crystal sheets up to 10 mm in size for 24 h. The surface morphology and structure of the crystals have been analyzed by optical microscopy and X-ray diffraction. C{sub 10}H{sub 8} and C{sub 14}H{sub 10} single crystals grow coplanarly along the (001) plane. A thermodynamic model of the flat-crystal nucleus formation at the liquid‒air interface, based on the analysis of the change in the free Gibbs energy, is considered.

  3. Physical properties of BeAl6O10 single crystals

    Science.gov (United States)

    Pestryakov, E. V.; Petrov, V. V.; Zubrinov, I. I.; Semenov, V. I.; Trunov, V. I.; Kirpichnikov, A. V.; Alimpiev, A. I.

    1997-10-01

    Single crystals of BeAl6O10, beryllium hexaaluminate, were grown by the Czochralski method. The optical, acousto-optical, elastic, and a number of thermo-mechanical properties of bulk crystals of BeAl6O10 were investigated in comparison with crystal of BeAl2O4, chrysoberyl. It has been demonstrated that this material is the promising host for active media of tunable solid state lasers.

  4. Growth, optical, thermal and mechanical studies of methyl 4-hydroxybenzoate single crystals

    Science.gov (United States)

    Vijayan, N.; Ramesh Babu, R.; Gunasekaran, M.; Gopalakrishnan, R.; Ramasamy, P.

    2003-08-01

    Bulk single crystals of methyl 4-hydroxy benzoate have been successfully grown by slow evaporation solution growth technique at room temperature. The grown crystals have been subjected to spectroscopic studies like FT-IR and FT-Raman. The hardness of the crystal was measured by Vicker's microhardness tester. The lattice parameters have been calculated by X-ray diffraction technique and the values are in good agreement with the reported JCPDS file.

  5. Structure and Properties of Reduced Barium Niobium Oxide Single Crystals Obtained from Borate Fluxes

    NARCIS (Netherlands)

    Hessen, B.; Sunshine, S.A.; Siegrist, T.; Fiory, A.T.; Waszczak, J.V.

    1991-01-01

    Single crystals of the reduced niobate Ba2Nb15O32 are produced by heating NbO2 in BaO·3B2O3 under high-vacuum conditions. The borate acts both as a source of BaO and as a flux for crystallization. The compound Ba2Nb15O32 crystallizes in space group R3 (a = 7.777 (1) Å, c = 35.518 (6) Å) and contains

  6. Strain-relief by single dislocation loops in calcite crystals grown on self-assembled monolayers

    Science.gov (United States)

    Ihli, Johannes; Clark, Jesse N.; Côté, Alexander S.; Kim, Yi-Yeoun; Schenk, Anna S.; Kulak, Alexander N.; Comyn, Timothy P.; Chammas, Oliver; Harder, Ross J.; Duffy, Dorothy M.; Robinson, Ian K.; Meldrum, Fiona C.

    2016-06-01

    Most of our knowledge of dislocation-mediated stress relaxation during epitaxial crystal growth comes from the study of inorganic heterostructures. Here we use Bragg coherent diffraction imaging to investigate a contrasting system, the epitaxial growth of calcite (CaCO3) crystals on organic self-assembled monolayers, where these are widely used as a model for biomineralization processes. The calcite crystals are imaged to simultaneously visualize the crystal morphology and internal strain fields. Our data reveal that each crystal possesses a single dislocation loop that occupies a common position in every crystal. The loops exhibit entirely different geometries to misfit dislocations generated in conventional epitaxial thin films and are suggested to form in response to the stress field, arising from interfacial defects and the nanoscale roughness of the substrate. This work provides unique insight into how self-assembled monolayers control the growth of inorganic crystals and demonstrates important differences as compared with inorganic substrates.

  7. Crystal front shape control by use of an additional heater in a Czochralski sapphire single crystal growth system

    Science.gov (United States)

    Hur, Min-Jae; Han, Xue-Feng; Choi, Ho-Gil; Yi, Kyung-Woo

    2017-09-01

    The quality of sapphire single crystals used as substrates for LED production is largely influenced by two defects: dislocation density and bubbles trapped in the crystal. In particular, the dislocation density has a higher value in sapphire grown by the Czochralski (CZ) method than by other methods. In the present study, we predict a decreased value for the convexity and thermal gradient at the crystal front (CF) through the use of an additional heater in an induction-heated CZ system. In addition, we develop a solute concentration model by which the location of bubble formation in CZ growth is calculated, and the results are compared with experimental results. We further calculate the location of bubble entrapment corresponding with the use of an additional heater. We find that sapphire crystal growth with an additional heater yields a decreased thermal gradient at the CF, together with decreased CF convexity, improved energy efficiency, and improvements in terms of bubble formation location.

  8. Interdiffusion behavior between NiAlHf coating and Ni-based single crystal superalloy with different crystal orientations

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ruili; Gong, Xueyuan [School of Materials Science and Engineering, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Peng, Hui [School of Materials Science and Engineering, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Ma, Yue, E-mail: mayue@buaa.edu.cn [School of Materials Science and Engineering, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Guo, Hongbo, E-mail: guo.hongbo@buaa.edu.cn [School of Materials Science and Engineering, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China)

    2015-01-30

    Highlights: • The interdiffusion behavior between the NiAlHf coating and the superalloy substrate was influenced by the crystal orientation of the substrate alloy. • The structure of TCP phases formed in SRZ and IDZ was studied. • Studying the effect of orientation crystal of substrate on the formation of SRZ. - Abstract: NiAlHf coatings were deposited onto Ni-based single crystal (SC) superalloy with different crystal orientations by electron beam physical vapor deposition (EB-PVD). The effects of the crystal orientations of the superalloy substrate on inter-diffusion behavior between the substrate and the NiAlHf coating were investigated. Substrate diffusion zone (SDZ) containing needle-like μ phases and interdiffusion zone (IDZ) mainly consisting of the ellipsoidal and rod-like μ phases were formed in the SC alloy after heat-treatment 10 h at 1100 °C. The thickness of secondary reaction zone (SRZ) formed in the SC alloy with (0 1 1) crystal orientation is about 14 μm after 50 h heat-treatment at 1100 °C, which is relatively thicker than that in the SC alloy with (0 0 1) crystal orientation, whereas the IDZ revealed similar thickness.

  9. Experimental realization of highly efficient broadband coupling of single quantum dots to a photonic crystal waveguide

    DEFF Research Database (Denmark)

    Lund-Hansen, Toke; Stobbe, Søren; Julsgaard, Brian;

    2008-01-01

    We present time-resolved spontaneous emission measurements of single quantum dots embedded in photonic crystal waveguides. Quantum dots that couple to a photonic crystal waveguide are found to decay up to 27 times faster than uncoupled quantum dots. From these measurements -factors of up to 0.89 ...

  10. Thermodynamics around the first-order ferromagnetic phase transition of Fe2P single crystals

    NARCIS (Netherlands)

    Hudl, M.; Campanini, D.; Caron, L.; Höglin, V.; Sahlberg, M.; Nordblad, P.; Rydh, A.

    2014-01-01

    The specific heat and thermodynamics of Fe2P single crystals around the first-order paramagnetic to ferromagnetic (FM) phase transition at TC≃217K are empirically investigated. The magnitude and direction of the magnetic field relative to the crystal axes govern the derived H−T phase diagram. Striki

  11. Single-crystal organic field-effect transistors based on dibenzo-tetrathiafulvalene

    NARCIS (Netherlands)

    Mas-Torrent, M.; Hadley, P.; Bromley, S.T.; Crivillers, N.; Veciana, J.; Rovira, C.

    2004-01-01

    We report on the fabrication and characterization of field-effect transistors based on single crystals of the organic semiconductor dibenzo-tetrathiafulvalene (DB-TTF). We demonstrate that it is possible to prepare very-good-quality DB-TTF crystals from solution. These devices show high field-effect

  12. Phase Transitions in a Non-Uniformly Stressed Iron Borate Single Crystal

    Science.gov (United States)

    Dzhuraev, D. R.; Niyazov, L. N.; Sokolov, B. Yu.

    2016-05-01

    Based on the Landau thermodynamic theory, phase transformations observed in a FeBO3 single crystal subject to spatially non-uniform mechanical stresses are analyzed. It is demonstrated that the main results of theoretical consideration of structural and magnetic phase transitions in the examined crystal do not contradict with the available experimental data.

  13. Distributed Feedback Lasers Based on Thiophene/Phenylene Co-Oligomer Single Crystals

    NARCIS (Netherlands)

    Fang, Hong-Hua; Ding, Ran; Lu, Shi-Yang; Yang, Jie; Zhang, Xu-Lin; Yang, Rui; Feng, Jing; Chen, Qi-Dai; Song, Jun-Feng; Sun, Hong-Bo; Fang, Honghua

    2012-01-01

    Organic crystals have great potential for the applications in laser devices. This article presents an effective approach for fabrication of distributed feedback single crystal lasers. With the laser interference ablation method, high quality grating structures have been fabricated on the organic sin

  14. Structural templating in a nonplanar phthalocyanine using single crystal copper iodide

    OpenAIRE

    Rochford, L. A. (Luke A.); Ramadan, Alexandra J.; Keeble, Dean S.; Ryan, Mary P.; Heutz, Sandrine; Jones, T S

    2015-01-01

    Solution-grown copper iodide crystals are used as substrates for the templated growth of the nonplanar vanadyl phthalocyanine using organic molecular beam deposition. Structural characterization reveals a single molecular orientation produced by the (111) Miller plane of the copper iodide crystals. These fundamental measurements show the importance of morphology and structure in templating interactions for organic electronics applications.

  15. ORIENTATIONAL MICRO-RAMAN SPECTROSCOPY ON HYDROXYAPATITE SINGLE-CRYSTALS AND HUMAN ENAMEL CRYSTALLITES

    NARCIS (Netherlands)

    TSUDA, H; ARENDS, J

    1994-01-01

    Single crystals of synthetic hydroxyapatite have been examined by orientational micro-Raman spectroscopy. The observed Raman bands include the PO43-/OH- internal and external. modes over the spectral range from 180 to 3600 cm(-1). The Raman-active symmetry tensors (A, E(1), and E(2)) of crystal-clas

  16. Magnetic excitations of single-crystal PrBa2Cu3O6.2

    DEFF Research Database (Denmark)

    Lister, S.J.S.; Boothroyd, A.T.; Andersen, N.H.;

    2000-01-01

    Measurements of the low-energy magnetic excitations in single-crystal PrBa2Cu3O6.2, and in YBa2Cu3O6.2 for comparison, have been performed using inelastic neutron scattering. An excitation with weak dispersion is seen, which is compared to a spin-wave model based on the lowest lying crystal field...

  17. Isothermal currents in InSe, GaSe, and GaS single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Micocci, G.; Rizzo, A.; Tepore, A.; Zuanni, F. (Lecce Univ. (Italy). Ist. di Fisica)

    1983-11-16

    Isothermal current-time measurements are performed on InSe, GaSe, and GaS single crystals. The results reveal the presence of trapping centres and their activation energies and capture cross-sections are determined. The limitations of this method for the determination of trapping parameters in crystals are also discussed.

  18. Crystal growth of pure and impurity-doped lead chloride single crystals from the melt

    NARCIS (Netherlands)

    Willemsen, B.

    An account is given of the purification and the crystal growing of lead chloride. Difficulties observed are blackening of the material and the formation of oxides. It is evident that oxygen should be avoided. The influence of water vapour is studied with mass spectroscopy, crystal microbalance

  19. Crystal growth of pure and impurity-doped lead chloride single crystals from the melt

    NARCIS (Netherlands)

    Willemsen, B.

    1971-01-01

    An account is given of the purification and the crystal growing of lead chloride. Difficulties observed are blackening of the material and the formation of oxides. It is evident that oxygen should be avoided. The influence of water vapour is studied with mass spectroscopy, crystal microbalance measu

  20. Single crystal and optical ceramic multicomponent garnet scintillators: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yuntao, E-mail: ywu52@utk.edu [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN 37996 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Luo, Zhaohua; Jiang, Haochuan [Ningbo Institution of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Meng, Fang [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN 37996 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Koschan, Merry [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN 37996 (United States); Melcher, Charles L. [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN 37996 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

    2015-04-21

    Multicomponent garnet materials can be made in optical ceramic as well as single crystal form due to their cubic crystal structure. In this work, high-quality Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:0.2 at% Ce (GGAG:Ce) single crystal and (Gd,Lu){sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:1 at% Ce (GLuGAG:Ce) optical ceramics were fabricated by the Czochralski method and a combination of hot isostatic pressing (HIPing) and annealing treatment, respectively. Under optical and X-ray excitation, the GLuGAG:Ce optical ceramic exhibits a broad Ce{sup 3+} transition emission centered at 550 nm, while the emission peak of the GGAG:Ce single crystal is centered at 540 nm. A self-absorption effect in GLuGAG:Ce optical ceramic results in this red-shift of the Ce{sup 3+} emission peak compared to that in the GGAG:Ce single crystal. The light yield under 662 keV γ-ray excitation was 45,000±2500 photons/MeV and 48,200±2410 photons/MeV for the GGAG:Ce single crystal and GLuGAG:Ce optical ceramic, respectively. An energy resolution of 7.1% for 662 keV γ-rays was achieved in the GLuGAG:Ce optical ceramic with a Hamamatsu R6231 PMT, which is superior to the value of 7.6% for a GGAG:Ce single crystal. Scintillation decay time measurements under {sup 137}Cs irradiation show two exponential decay components of 58 ns (47%) and 504 ns (53%) for the GGAG:Ce single crystal, and 84 ns (76%) and 148 ns (24%) for the GLuGAG:Ce optical ceramic. The afterglow level after X-ray cutoff in the GLuGAG:Ce optical ceramic is at least one order of magnitude lower than in the GGAG:Ce single crystal. - Highlights: • GGAG:Ce single crystal and GLuGAG:Ce optical ceramics were fabricated. • The light yield of both ceramic and crystal G(Lu)GAG:Ce reached the level of 45,000 photons/MeV. • GLuGAG:Ce optical ceramic showed a better energy resolution of 7.1% for 662 keV. • GLuGAG:Ce ceramics exhibited lower afterglow level than that of GGAG:Ce single crystals. • The possible optimization strategies for

  1. Methods for producing single crystal mixed halide perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Kai; Zhao, Yixin

    2017-07-11

    An aspect of the present invention is a method that includes contacting a metal halide and a first alkylammonium halide in a solvent to form a solution and maintaining the solution at a first temperature, resulting in the formation of at least one alkylammonium halide perovskite crystal, where the metal halide includes a first halogen and a metal, the first alkylammonium halide includes the first halogen, the at least one alkylammonium halide perovskite crystal includes the metal and the first halogen, and the first temperature is above about 21.degree. C.

  2. Luminescent properties of diamond single crystals of pyramidal shape

    Science.gov (United States)

    Alekseev, A. M.; Tuyakova, F. T.; Obraztsova, E. A.; Korostylev, E. V.; Klinov, D. V.; Prusakov, K. A.; Malykhin, S. A.; Ismagilov, R. R.; Obraztsov, A. N.

    2016-11-01

    The luminescence properties of needle-like crystals of diamond, obtained by selective oxidation of textured polycrystalline diamond films, are studied. Diamond films were grown by chemical vapor deposition from a methane-hydrogen mixture activated by a DC discharge. The spectra of photo- and cathodoluminescence and the spatial distribution of the intensity of radiation at different wavelengths are obtained for individual needle-like crystals. Based on the spectral characteristics, conclusions are made about the presence of optically active defects containing nitrogen and silicon impurities in their structure, as well as the significant effect of structural defects on their luminescence spectra.

  3. III-V semiconductor solid solution single crystal growth

    Science.gov (United States)

    Gertner, E. R.

    1982-01-01

    The feasibility and desirability of space growth of bulk IR semiconductor crystals for use as substrates for epitaxial IR detector material were researched. A III-V ternary compound (GaInSb) and a II-VI binary compound were considered. Vapor epitaxy and quaternary epitaxy techniques were found to be sufficient to permit the use of ground based binary III-V crystals for all major device applications. Float zoning of CdTe was found to be a potentially successful approach to obtaining high quality substrate material, but further experiments were required.

  4. single crystal growth, x-ray structure analysis, optical band gap ...

    African Journals Online (AJOL)

    2015-09-01

    Sep 1, 2015 ... absorption spectra illustrate the change in opticalband gap from 3.01eVto ... Keywords: Single crystal growth; structure analysis; optical Eg; Raman spectra; strain tensor ... Journal of Fundamental and Applied Sciences.

  5. Molecular Surface Chemistry by Metal Single Crystals and Nanoparticles from Vacuum to High Pressure.

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, Gabor A.; Park, Jeong Y.

    2008-04-05

    Model systems for studying molecular surface chemistry have evolved from single crystal surfaces at low pressure to colloidal nanoparticles at high pressure. Low pressure surface structure studies of platinum single crystals using molecular beam surface scattering and low energy electron diffraction techniques probe the unique activity of defects, steps and kinks at the surface for dissociation reactions (H-H, C-H, C-C, O{double_bond}O bonds). High-pressure investigations of platinum single crystals using sum frequency generation vibrational spectroscopy have revealed the presence and the nature of reaction intermediates. High pressure scanning tunneling microscopy of platinum single crystal surfaces showed adsorbate mobility during a catalytic reaction. Nanoparticle systems are used to determine the role of metal-oxide interfaces, site blocking and the role of surface structures in reactive surface chemistry. The size, shape and composition of nanoparticles play important roles in determining reaction activity and selectivity.

  6. Single Crystal Piezoelectric Deformable Mirrors with High Actuator Density and Large Stroke Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Single crystal piezoelectric deformable mirrors with high actuator density, fine pitch, large stroke and no floating wires will be developed for future NASA science...

  7. Single Crystal Piezomotor for Large Stroke, High Precision and Cryogenic Actuations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes a novel single crystal piezomotor for large stroke, high precision, and cryogenic actuations with capability of position set-hold with...

  8. Advanced Electroactive Single Crystal and Polymer Actuators for Passive Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Large stroke and high precision electroactive single crystal and polymer actuators are desired for cryogenic passive optics such as Fabry-Perot Interferometer (FPI)...

  9. Superconducting properties of “111” type LiFeAs iron arsenide single crystals

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    LiFeAs single crystal has been grown with superconducting transition temperature Tc comparable to that of polycrystals.A magnetic transition is found at about 160 K,which suggests the correlation of superconductivity with spin wave density.

  10. Comparative study of ceramic and single crystal Ce:GAGG scintillator

    Science.gov (United States)

    Yanagida, Takayuki; Kamada, Kei; Fujimoto, Yutaka; Yagi, Hideki; Yanagitani, Takagimi

    2013-10-01

    Recent study revealed that single crystal Ce:Gd3(Al,Ga)5O12 (Ce:GAGG) showed good scintillation response under γ-ray exposure. We discover here that ceramic Ce:GAGG scintillator exhibited better performance than the single crystal counterpart. We developed Ce 1% doped ceramic and single crystal GAGG scintillators with 1 mm thick and compared their properties. In radioluminescence spectra, they showed intense emission peaking at 530 nm due to Ce3+ 5d-4f transition. The 137Cs γ-ray induced light yields of ceramic and single crystal resulted 70 000 ph/MeV and 46 000 ph/MeV with primary decay times of 165 and 143 ns, respectively. At present, the observed light yield was the brightest in oxide scintillators.

  11. Effect of L-Valine on the growth and characterization of Sodium Acid Phthalate (SAP) single crystals.

    Science.gov (United States)

    Nirmala, L Ruby; Thomas Joseph Prakash, J

    2013-06-01

    Undoped and amino acid doped good quality single crystals of Sodium Acid Phthalate crystals (SAP) were grown by slow evaporation solution growth technique which are semiorganic in nature. The effect of amino acid (L-Valine) dopant on the growth and the properties of SAP single crystal was investigated. The single crystal X-ray diffraction studies and FT-IR studies were carried out to identify the crystal structure and the presence of functional groups in undoped and L-Valine doped SAP crystals. The transparent nature of the grown crystal was observed using UV-Visible spectrum. The thermal decomposition of the doped SAP crystals was investigated by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). The enhancement in the NLO property of the undoped and L-Valine doped SAP crystals using KDP crystal as a reference was studied using SHG measurements. Vickers micro hardness measurements are used for the study of mechanical strength of the grown crystals.

  12. Effect of L-Valine on the growth and characterization of Sodium Acid Phthalate (SAP) single crystals

    Science.gov (United States)

    Nirmala, L. Ruby; Prakash, J. Thomas Joseph

    2013-06-01

    Undoped and amino acid doped good quality single crystals of Sodium Acid Phthalate crystals (SAP) were grown by slow evaporation solution growth technique which are semiorganic in nature. The effect of amino acid (L-Valine) dopant on the growth and the properties of SAP single crystal was investigated. The single crystal X-ray diffraction studies and FT-IR studies were carried out to identify the crystal structure and the presence of functional groups in undoped and L-Valine doped SAP crystals. The transparent nature of the grown crystal was observed using UV-Visible spectrum. The thermal decomposition of the doped SAP crystals was investigated by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). The enhancement in the NLO property of the undoped and L-Valine doped SAP crystals using KDP crystal as a reference was studied using SHG measurements. Vickers micro hardness measurements are used for the study of mechanical strength of the grown crystals.

  13. Growth and characterization of new semi-organic L-proline strontium chloride monohydrate single crystals

    Science.gov (United States)

    Gupta, Manoj K.; Sinha, Nidhi; Kumar, Binay

    2011-01-01

    The present communication deals with the synthesis, single crystal growth and characterization of a new nonlinear optical material L-proline strontium chloride monohydrate ( L-PSCM). Single crystals have been grown using the slow solvent evaporation technique. Single crystal XRD analysis confirmed that the crystal belongs to the orthorhombic structure with lattice parameter a=6.6966(3) Å, b=12.4530(5) Å, c=15.2432(5) Å and space group P2 12 12 1. Presence of various functional groups in L-PSCM and protonation of the ions were confirmed by Fourier transform infrared spectroscopy (FT-IR) analysis. The melting point of the single crystal was found to be 126 °C using DSC. Ultraviolet-visible spectral analyses showed that the crystal has low UV cut-off at 226 nm combined with very good transparency of 90% in a wide range. The optical band gap was estimated to be 5.82 eV. Capacitance and dielectric-loss measurements were carried out at different temperatures in the frequency range 1 kHz-2 MHz. The dielectric constant and loss factor were found to be 21 and 0.03 at 1 kHz at room temperature, respectively. Microhardness mechanical studies show that hardness number ( Hv) increases with load for L-PSCM single crystals the by Vickers microhardness method. Second harmonic generation (SHG) efficiency was found to be 0.078 times the value of KDP.

  14. Polycrystal deformation and single crystal deformation: Dislocation structure and flow stress in copper

    DEFF Research Database (Denmark)

    Huang, X.; Borrego, A.; Pantleon, W.

    2001-01-01

    of microstructures have been identified. A correlation is found between microstructure and grain orientation, which agrees well with earlier observations in tensile deformed aluminum polycrystals and copper single crystals. The stress–strain curve of the copper polycrystal is calculated with good accuracy from...... single crystal data, which are weighted according to the volume fractions of the three different types based on a quantitative texture measurement of the polycrystal....

  15. Enhancement of below gap transmission of InAs single crystal via suppression of native defects

    Science.gov (United States)

    Shen, Guiying; Zhao, Youwen; Dong, Zhiyuan; Liu, Jingming; Xie, Hui; Bai, Yongbiao; Chen, Xiaoyu

    2017-03-01

    As-grown and annealed undoped n type InAs single crystals have been studied by Hall effect measurement, infrared transmission (IR) spectroscopy, photoluminescence spectroscopy (PL) and glow discharge mass spectroscopy (GDMS). After annealing, below-gap infrared transmittance of the InAs single crystal increases significantly with the annihilation of a 0.383 eV PL peak related defect. Mechanism of the transmission enhancement and the attribution of the defect is discussed based on the experimental results.

  16. Solid-State Conformational Flexibility at Work: Zipping and Unzipping within a Cyclic Peptoid Single Crystal.

    Science.gov (United States)

    Meli, Alessandra; Macedi, Eleonora; De Riccardis, Francesco; Smith, Vincent J; Barbour, Leonard J; Izzo, Irene; Tedesco, Consiglia

    2016-04-01

    A peptidomimetic compound undergoes a reversible single-crystal-to-single-crystal transformation upon guest release/uptake with the transformation involving a drastic conformational change. The extensive and reversible alteration in the solid state is connected to the formation of an unprecedented "CH-π zipper" which can reversibly open and close (through the formation of CH-π interactions), thus allowing for guest sensing.

  17. Anisotropic Laminar Piezocomposite Actuator Incorporating Machined PMN-PT Single Crystal Fibers

    Science.gov (United States)

    Wilkie, W. Keats; Inman, Daniel J.; Lloyd, Justin M.; High, James W.

    2006-01-01

    The design, fabrication, and testing of a flexible, laminar, anisotropic piezoelectric composite actuator utilizing machined PMN-32%PT single crystal fibers is presented. The device consists of a layer of rectangular single crystal piezoelectric fibers in an epoxy matrix, packaged between interdigitated electrode polyimide films. Quasistatic free-strain measurements of the single crystal device are compared with measurements from geometrically identical specimens incorporating polycrystalline PZT-5A and PZT-5H piezoceramic fibers. Free-strain actuation of the single crystal actuator at low bipolar electric fields (+/- 250 V/mm) is approximately 400% greater than that of the baseline PZT-5A piezoceramic device, and 200% greater than that of the PZT-5H device. Free-strain actuation under high unipolar electric fields (0-4kV/mm) is approximately 200% of the PZT-5A baseline device, and 150% of the PZT-5H alternate piezoceramic device. Performance increases at low field are qualitatively consistent with predicted increases based on scaling the low-field d33 piezoelectric constants of the respective piezoelectric materials. High-field increases are much less than scaled d33 estimates, but appear consistent with high-field freestrain measurements reported for similar bulk single-crystal and piezoceramic compositions. Measurements of single crystal actuator capacitance and coupling coefficient are also provided. These properties were poorly predicted using scaled bulk material dielectric and coupling coefficient data. Rules-of-mixtures calculations of the effective elastic properties of the single crystal device and estimated actuation work energy densities are also presented. Results indicate longitudinal stiffnesses significantly lower (50% less) than either piezoceramic device. This suggests that single-crystal piezocomposite actuators will be best suited to low induced-stress, high strain and deflection applications.

  18. Anisotropic Piezocomposite Actuator Incorporating Machined PMN-PT Single Crystal Fibers

    Science.gov (United States)

    Wilkie, W. Keats; Inman, Daniel J.; Lloyd, Justin M.; High, James W.

    2004-01-01

    The design, fabrication, and testing of a flexible, planar, anisotropic piezoelectric composite actuator utilizing machined PMN-32%PT single crystal fibers is presented. The device consists of a layer of rectangular single crystal piezoelectric fibers in an epoxy matrix, packaged between interdigitated electrode polyimide films. Quasistatic free-strain measurements of the single crystal device are compared with measurements from geometrically identical specimens incorporating polycrystalline PZT-5A and PZT-5H piezoceramic fibers. Free-strain actuation of the single crystal actuator at low bipolar electric fields (+/- 250 V/mm) is approximately 400% greater than that of the baseline PZT-5A piezoceramic device, and 200% greater than that of the PZT-5H device. Free-strain actuation under high unipolar electric fields (0-4kV/mm) is approximately 200% of the PZT-5A baseline device, and 150% of the PZT-5H alternate piezoceramic device. Performance increases at low field are qualitatively consistent with predicted increases based on scaling the low-field d(sub 33) piezoelectric constants of the respective piezoelectric materials. High-field increases are much less than scaled d(sub 33) estimates, but appear consistent with high-field freestrain measurements reported for similar bulk single-crystal and piezoceramic compositions. Measurements of single crystal actuator capacitance and coupling coefficient are also provided. These properties were poorly predicted using scaled bulk material dielectric and coupling coefficient data. Rules-of-mixtures calculations of the effective elastic properties of the single crystal device and estimated actuation work energy densities are also presented. Results indicate longitudinal stiffnesses significantly lower (50% less) than either piezoceramic device. This suggests that single-crystal piezocomposite actuators will be best suited to low induced-stress, high strain and deflection applications.

  19. Single crystals of bismuth silicon oxide grown by the Czochralski technique and their characterisation

    Directory of Open Access Journals (Sweden)

    ANDREJA VALCIC

    1999-09-01

    Full Text Available Single crystals of Bi12SiO20 were grown by the Czochralski technique. The critical diameter and the critical rate of rotation were calculated. Suitable polishing and etching solutions were determined. X-Ray measurements were performed on powdered samples to obtain the lattice parameters. The optical properties of the bismuth silicon oxide single crystals were investigated. The obtained results are discussed and compared with published data.

  20. A Method of Stray Grain Suppression for Single-Crystal Superalloy During Seed Melt-Back

    Science.gov (United States)

    Xuan, Weidong; Lan, Jian; Liu, Huan; Li, Chuanjun; Zhong, Yunbo; Ren, Xingfu; Li, Xi; Cao, Guanghui; Ren, Zhongming

    2016-12-01

    The suppression of stray grains during seed melt-back of single-crystal superalloy through thermal resistance technique has been investigated based on both experimental observations and numerical simulation. The results indicate that the introduction of thermal resistance layer significantly suppresses the stray grain formation of single-crystal superalloy. Based on both theoretical analysis and numerical simulation, above results should be attributed to the decrease of radial heat transfer of sample in the thermal resistance layer.

  1. Frustration and single crystal morphology of isotactic poly(2-vinylpyridine)

    NARCIS (Netherlands)

    Okihara, T; Cartier, L; van Ekenstein, GORA; Lotz, B

    1999-01-01

    The crystal structure of isotactic poly(2-vinylpyridine) (iP2VP) established in 1977 by Puterman et al. is shown to conform to a recently proposed frustrated packing scheme which involves three isochiral three-fold helices packed in a trigonal unit-cell, and observed in a number of polymers and biop

  2. Solution Growth and Characterization of Single Crystals on Earth and in Microgravity

    Science.gov (United States)

    Aggarwal, M. D.; Currie, J. R.; Penn, B. G.; Batra, A. K.; Lal, R. B.

    2007-01-01

    Crystal growth has been of interest to physicists and engineers for a long time because of their unique properties. Single crystals are utilized in such diverse applications as pharmaceuticals, computers, infrared detectors, frequency measurements, piezoelectric devices, a variety of high-technology devices, and sensors. Solution crystal growth is one of the important techniques to grow a variety of crystals when the material decomposes at the melting point and a suitable solvent is available to make a saturated solution at a desired temperature. In this Technical Memorandum (TM) an attempt is made to give the fundamentals of growing crystals from solution including improved designs of various crystallizers. Since the same solution crystal growth technique could not be used in microgravity, the authors proposed a new cooled-sting technique to grow crystals in space. The authors experience from conducting two Space Shuttle solution crystal growth experiments are also detailed in this TM and the complexity of solution growth experiments to grow crystals in space are also discussed. These happen to be some of the early experiments performed in space, and various lessons learned are described. A brief discussion of protein crystal growth that shares basic principles of the solution growth technique is given, along with some flight hardware information for growth in microgravity.

  3. Micro pulling down growth of very thin shape memory alloys single crystals

    Science.gov (United States)

    López-Ferreño, I.; Juan, J. San; Breczewski, T.; López, G. A.; Nó, M. L.

    Shape memory alloys (SMAs) have attracted much attention in the last decades due to their thermo-mechanical properties such as superelasticity and shape memory effect. Among the different families of SMAs, Cu-Al-Ni alloys exhibit these properties in a wide range of temperatures including the temperature range of 100-200∘C, where there is a technological demand of these functional materials, and exhibit excellent behavior at small scale making them more competitive for applications in Micro Electro-Mechanical Systems (MEMS). However, polycrystalline alloys of Cu-based SMAs are very brittle so that they show their best thermo-mechanical properties in single-crystal state. Nowadays, conventional Bridgman and Czochralski methods are being applied to elaborate single-crystal rods up to a minimum diameter of 1mm, but no works have been reported for smaller diameters. With the aim of synthesizing very thin single-crystals, the Micro-Pulling Down (μ-PD) technique has been applied, for which the capillarity and surface tension between crucible and the melt play a critical role. The μ-PD method has been successfully applied to elaborate several cylindrical shape thin single-crystals down to 200μm in diameter. Finally, the martensitic transformation, which is responsible for the shape memory properties of these alloys, has been characterized for different single-crystals. The experimental results evidence the good quality of the grown single-crystals.

  4. High performance relaxor-based ferroelectric single crystals for ultrasonic transducer applications.

    Science.gov (United States)

    Chen, Yan; Lam, Kwok-Ho; Zhou, Dan; Yue, Qingwen; Yu, Yanxiong; Wu, Jinchuan; Qiu, Weibao; Sun, Lei; Zhang, Chao; Luo, Haosu; Chan, Helen L W; Dai, Jiyan

    2014-07-29

    Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) have drawn much attention in the ferroelectric field because of their excellent piezoelectric properties and high electromechanical coupling coefficients (d33~2000 pC/N, kt~60%) near the morphotropic phase boundary (MPB). Ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals also possess outstanding performance comparable with PMN-PT single crystals, but have higher phase transition temperatures (rhombohedral to tetragonal Trt, and tetragonal to cubic Tc) and larger coercive field Ec. Therefore, these relaxor-based single crystals have been extensively employed for ultrasonic transducer applications. In this paper, an overview of our work and perspectives on using PMN-PT and PIN-PMN-PT single crystals for ultrasonic transducer applications is presented. Various types of single-element ultrasonic transducers, including endoscopic transducers, intravascular transducers, high-frequency and high-temperature transducers fabricated using the PMN-PT and PIN-PMN-PT crystals and their 2-2 and 1-3 composites are reported. Besides, the fabrication and characterization of the array transducers, such as phased array, cylindrical shaped linear array, high-temperature linear array, radial endoscopic array, and annular array, are also addressed.

  5. High Performance Relaxor-Based Ferroelectric Single Crystals for Ultrasonic Transducer Applications

    Directory of Open Access Journals (Sweden)

    Yan Chen

    2014-07-01

    Full Text Available Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3O3-PbTiO3 (PMN-PT have drawn much attention in the ferroelectric field because of their excellent piezoelectric properties and high electromechanical coupling coefficients (d33~2000 pC/N, kt~60% near the morphotropic phase boundary (MPB. Ternary Pb(In1/2Nb1/2O3-Pb(Mg1/3Nb2/3O3-PbTiO3 (PIN-PMN-PT single crystals also possess outstanding performance comparable with PMN-PT single crystals, but have higher phase transition temperatures (rhombohedral to tetragonal Trt, and tetragonal to cubic Tc and larger coercive field Ec. Therefore, these relaxor-based single crystals have been extensively employed for ultrasonic transducer applications. In this paper, an overview of our work and perspectives on using PMN-PT and PIN-PMN-PT single crystals for ultrasonic transducer applications is presented. Various types of single-element ultrasonic transducers, including endoscopic transducers, intravascular transducers, high-frequency and high-temperature transducers fabricated using the PMN-PT and PIN-PMN-PT crystals and their 2-2 and 1-3 composites are reported. Besides, the fabrication and characterization of the array transducers, such as phased array, cylindrical shaped linear array, high-temperature linear array, radial endoscopic array, and annular array, are also addressed.

  6. Anisotropic surface hole-transport property of triphenylamine-derivative single crystal prepared by solution method

    Science.gov (United States)

    Umeda, Minoru; Katagiri, Mitsuhiko; Shironita, Sayoko; Nagayama, Norio

    2016-12-01

    This paper reports the anisotropic hole transport at the triphenylamine-derivative single crystal surface prepared by a solution method. Triphenylamine derivatives are commonly used in a hole-transport material for organic photoconductors of laser-beam printers, in which the materials are used as an amorphous form. For developing organic photovoltaics using the photoconductor's technology, preparation of a single crystal seems to be a specific way by realizing the high mobility of an organic semiconductor. In this study, a single crystal of 4-(2,2-diphenylethenyl)-N,N-bis(4-methylphenyl)-benzenamine (TPA) was prepared and its anisotropic hole-transport property measured. First, the hole-transport property of the TPA was investigated based on its chemical structure and electrochemical redox characteristics. Next, a large-scale single crystal formation at a high rate was developed by employing a solution method based on its solubility and supersolubility curves. The grown TPA was found to be a single crystal based on the polarization micrograph observation and crystallographic analysis. For the TPA single crystal, an anisotropic surface conduction was found, which was well explained by its molecular stack structure. The measured current in the long-axis direction is one order of magnitude greater than that of amorphous TPA.

  7. Perovskite single crystals and thin films for optoelectronic devices (Conference Presentation)

    Science.gov (United States)

    Li, Gang; Han, Qifeng; Yang, Yang; Bae, Sang-Hoon; Sun, Pengyu

    2016-09-01

    Hybrid organolead trihalide perovskite (OTP) solar cells have developed as a promising candidate in photovoltaics due to their excellent properties including a direct bandgap, strong absorption coefficient, long carrier lifetime, and high mobility. Most recently, formamidinium (NH2CH=NH2+ or FA) lead iodide (FAPbI3) has attracted significant attention due to several advantages: (1) the larger organic FA cation can replace the MA cation and form a more symmetric crystal structure, (2) the smaller bandgap of FAPbI3 allows for near infrared (NIR) absorption, and (3) FAPbI3 has an elevated decomposition temperature and thus potential to improve stability. Single crystals provide an excellent model system to study the intrinsic electrical and optical properties of these materials due to their high purity, which is particularly important to understand the limits of these materials. In this work, we report the growth of large ( 5 millimeter size) single crystal FAPbI3 using a novel liquid based crystallization method. The single crystal FAPbI3 demonstrated a δ-phase to α-phase transition with a color change from yellow to black when heated to 185°C within approximately two minutes. The crystal structures of the two phases were identified and the PL emission peak of the α-phase FAPbI3 (820 nm) shows clear red-shift compared to the FAPbI3 thin film (805 nm). The FAPbI3 single crystal shows a long carrier lifetime of 484 ns, a high carrier mobility of 4.4 cm2·V-1·s-1, and even more interestingly a conductivity of 1.1 × 10-7(ohm·cm)-1, which is approximately one order of magnitude higher than that of the MAPbI3 single crystal. Finally, high performance photoconductivity type photodetectors were successfully demonstrated using the single crystal FAPbI3.

  8. Pyroelectric electron emissions and domain inversion of LiNbO{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong-Wook [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600 (Korea, Republic of)]. E-mail: Peterkim@ucsd.edu; Bourim, E.M. [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600 (Korea, Republic of); Jeong, Soo-Hwan [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600 (Korea, Republic of); Yoo, In K. [Samsung Advanced Institute of Technology, U-Team, P.O. Box 111, Suwon, Kyongki 440-600, Korea (Korea)

    2004-10-30

    We investigated the electron emissions from a congruent LiNbO{sub 3} single crystal with variation in temperature. When there was a small gap between the crystal and detector (<2 mm), we observed abrupt drops in the emission current and polarization domain inversion of the crystal. The current burst was distributed in tree-like patterns that suggested plasma generation. A sufficient gap and a crystal with a high coercive field appear to be factors that allow reproducible electron emissions from pyroelectric materials.

  9. Single crystal growth in spin-coated films of polymorphic phthalocyanine derivative under solvent vapor

    Energy Technology Data Exchange (ETDEWEB)

    Higashi, T.; Ohmori, M.; Ramananarivo, M. F.; Fujii, A., E-mail: afujii@opal.eei.eng.osaka-u.ac.jp; Ozaki, M. [Division of Electrical, Electronic, and Information Engineering, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan)

    2015-12-01

    The effects of solvent vapor on spin-coated films of a polymorphic phthalocyanine derivative were investigated. Growth of single crystal films via redissolving organic films under solvent vapor was revealed by in situ microscopic observations of the films. X-ray diffraction measurement of the films after exposing to solvent vapor revealed the phase transition of polymorphs under solvent vapor. The direction of crystal growth was clarified by measuring the crystal orientation in a grown monodomain film. The mechanism of crystal growth based on redissolving organic films under solvent vapor was discussed in terms of the different solubilities of the polymorphs.

  10. Single crystal growth in spin-coated films of polymorphic phthalocyanine derivative under solvent vapor

    Directory of Open Access Journals (Sweden)

    T. Higashi

    2015-12-01

    Full Text Available The effects of solvent vapor on spin-coated films of a polymorphic phthalocyanine derivative were investigated. Growth of single crystal films via redissolving organic films under solvent vapor was revealed by in situ microscopic observations of the films. X-ray diffraction measurement of the films after exposing to solvent vapor revealed the phase transition of polymorphs under solvent vapor. The direction of crystal growth was clarified by measuring the crystal orientation in a grown monodomain film. The mechanism of crystal growth based on redissolving organic films under solvent vapor was discussed in terms of the different solubilities of the polymorphs.

  11. The Growth of p-Type AIII BIII C2V I Single Crystals

    OpenAIRE

    2000-01-01

    AIIIBIIIC2VI single crystals were grown by the modified Bridgman-Stockbarger method, a procedure similar to direct freezing in our crystal growth laboratory. AIIIBIIIC2VI compounds are collected into two groups (III. group: TI, Ga, In and VI. group: Se, S, Te): 1. TlGaSe2, TlGaS2 and TlInS2 have layer structure. 2. TlInSe2, TlInTe2 and TlGaTe2 have chained structure. The main reasons such crystals grown with this method is similar to the direct freezing method because 1) quality of crystals i...

  12. Growth and characterization of Sm3+ doped cerium oxalate single crystals

    Directory of Open Access Journals (Sweden)

    Minu Mary C

    2016-07-01

    Full Text Available Single crystals of Sm3+ doped cerium oxalate decahydrate were synthesized using single diffusion gel technique and the conditions influencing the size, morphology, nucleation density and quality of the crystals were optimized. Highly transparent single crystals of average size 3 mm × 2 mm × 1 mm with well-defined hexagonal morphology were grown during a time period of two weeks. X-ray powder diffraction analysis revealed that the grown crystals crystallize in the monoclinic system with space group P21/c as identical with the pure cerium oxalate. The various functional groups of the oxalate ligand and the water of crystallization were identified by Fourier transform infrared spectroscopy. The photoluminescence spectrum of the Sm3+ doped cerium oxalate indicated that the Sm3+ ions are optically active in the cerium oxalate matrix. The crystal has a strong and efficient orange red emission with a wavelength peak at 595 nm and hence can be effectively used for optical amplification. Microhardness measurements of the crystal revealed that they belong to the soft material category.

  13. Morphological and mechanical characterization of composite calcite/SWCNT-COOH single crystals.

    Science.gov (United States)

    Calvaresi, Matteo; Falini, Giuseppe; Pasquini, Luca; Reggi, Michela; Fermani, Simona; Gazzadi, Gian Carlo; Frabboni, Stefano; Zerbetto, Francesco

    2013-08-01

    A growing number of classes of organic (macro)molecular materials have been trapped into inorganic crystalline hosts, such as calcite single crystals, without significantly disrupting their crystalline lattices. Inclusion of an organic phase plays a key role in enhancing the mechanical properties of the crystals, which are believed to share structural features with biogenic minerals. Here we report the synthesis and mechanical characterization of composite calcite/SWCNT-COOH single crystals. Once entrapped into the crystals SWCNT-COOH appeared both as aggregates of entangled bundles and nanoropes. Their observation was possible only after crystal etching, fracture or FIB (focused ion beam) cross-sectioning. SWCNT-COOHs occupied a small volume fraction and were randomly distributed into the host crystal. They did not strongly affect the crystal morphology. However, although the Young's modulus of composite calcite/SWCNT-COOH single crystals was similar to that of pure calcite their hardness increased by about 20%. Thus, SWCNT-COOHs provide an obstacle against the dislocation-mediated propagation of plastic deformation in the crystalline slip systems, in analogy with the well-known hardness increase in fiber-reinforced composites.

  14. Magnetic field controlled single crystal growth and surface modification of titanium alloys exposed for biocompatibility

    Science.gov (United States)

    Hermann, Regina; Uhlemann, Margitta; Wendrock, Horst; Gerbeth, Gunter; Büchner, Bernd

    2011-03-01

    The aim of this work is growth and characterisation of Ti55Nb45 (wt%) single crystals by floating-zone single crystal growth of intermetallic compounds using two-phase radio-frequency (RF) electromagnetic heating. Thereby, the process and, in particular, the flow field in the molten zone is influenced by additional magnetic fields. The growth of massive intermetallic single crystals is very often unsuccessful due to an unfavourable solid-liquid interface geometry enclosing concave fringes. It is generally known that the crystallization process stability is enhanced if the crystallization interface is convex. For this, a tailored magnetic two-phase stirrer system has been developed, which enables a controlled influence on the melt ranging from intensive inwards to outwards flows. Since Ti is favourably light, strong and biocompatible, it is one of the few materials that naturally match the requirements for implantation in the human body. Therefore, the magnetic system was applied to crystal growth of Ti alloys. The grown crystals were oriented and cut to cubes with the desired crystallographic orientations [1 0 0] and [1 0 1] normally on a plane. The electron backscatter diffraction (EBSD) technique was applied to clearly determine crystal orientation and to localize grain boundaries. The formation of oxidic nanotubes on Ti surfaces in dependence of the grain orientation was investigated, performed electrochemically by anodic oxidation from fluoride containing electrolyte.

  15. Results on the Coherent Interaction of High Energy Electrons and Photons in Oriented Single Crystals

    CERN Document Server

    Apyan, A; Badelek, B; Ballestrero, S; Biino, C; Birol, I; Cenci, P; Connell, S H; Eichblatt, S; Fonseca, T; Freund, A; Gorini, B; Groess, R; Ispirian, K; Ketel, T; Kononets, Y V; López, A; Mangiarotti, A; Van Rens, B; Sellschop, J P Friedel; Shieh, M; Sona, P; Strakhovenko, V M; Uggerhøj, Erik; Uggerhøj, U; Ünel, G; Velasco, M; Vilakazi, Z Z; Wessely, O; Kononets, Yu.V.

    2005-01-01

    The CERN-NA-59 experiment examined a wide range of electromagnetic processes for multi-GeV electrons and photons interacting with oriented single crystals. The various types of crystals and their orientations were used for producing photon beams and for converting and measuring their polarisation. The radiation emitted by 178 GeV unpolarised electrons incident on a 1.5 cm thick Si crystal oriented in the Coherent Bremsstrahlung (CB) and the String-of-Strings (SOS) modes was used to obtain multi-GeV linearly polarised photon beams. A new crystal polarimetry technique was established for measuring the linear polarisation of the photon beam. The polarimeter is based on the dependence of the Coherent Pair Production (CPP) cross section in oriented single crystals on the direction of the photon polarisation with respect to the crystal plane. Both a 1 mm thick single crystal of Germanium and a 4 mm thick multi-tile set of synthetic Diamond crystals were used as analyzers of the linear polarisation. A birefringence ...

  16. Introduction to the Growth of Bulk Single Crystals of Two-Dimensional Transition-Metal Dichalcogenides

    Science.gov (United States)

    Ueno, Keiji

    2015-12-01

    Semiconducting two-dimensional transition-metal dichalcogenides (MX2) are attracting much attention as promising materials for a new generation of optical and electronic devices. MX2 compounds are complementary or competitive to graphene because of the existence of a native band gap. The growth of large and high-quality bulk single crystals is one of the critical issues for the application of MX2 compounds, whose bulk crystals are generally grown by the chemical vapor transport (CVT) method. In the present review, I introduce experimental techniques required for the CVT growth of high-quality MX2 single crystals.

  17. SOLIDIFICATION OF NICKEL-BASED SINGLE CRYSTAL SUPERALLOY BY ELECTRIC FIELD

    Institute of Scientific and Technical Information of China (English)

    Y.S. Yang; X.H. Feng; G.F. Cheng; Y.J. Li; Z.Q. Hu

    2005-01-01

    The crystal growth of a nickel-based single crystal superalloy DD3 was researched via controlled directional solidification under the action of a DC electric field. The cellular or dendrite spacing of the single crystal superalloy is refined and microsegregation of alloying elements Al,Ti, Mo and W, is reduced by the electric field. The electric field decreases the interface stability and reduces the critical growth rate of the cellular-dendritic translation because of Thomson effect and Joule heating. The precipitation of the γ' phase is more uniform and the size of the γ'phase is smaller with the electric field than that without the electric field.

  18. Tensile plastic strain localization in single crystals of austenite steel electrolytically saturated with hydrogen

    Science.gov (United States)

    Barannikova, S. A.; Nadezhkin, M. V.; Mel'Nichuk, V. A.; Zuev, L. B.

    2011-09-01

    The effect of interstitial hydrogen atoms on the mechanical properties and plastic strain localization patterns in tensile tested Fe-18Cr-12Ni-2Mo single crystals of austenite steel with low stacking-fault energy has been studied using a double-exposure speckle photography technique. The main parameters of plastic-flow localization at various stages of the deformation hardening of crystals have been determined in single crystals of steel electrolytically saturated with hydrogen in a three-electrode electrochemical cell at a controlled constant cathode potential.

  19. Unidirectional growth, rocking curve, linear and nonlinear optical properties of LPHCl single crystals

    Science.gov (United States)

    Kumar, P. Ramesh; Gunaseelan, R.; Raj, A. Antony; Selvakumar, S.; Sagayaraj, P.

    2012-06-01

    Nonlinear optical amino-acid single crystal of L-phenylalanine hydrochloride (LPHCl) was successfully grown by unidirectional Sankaranarayanan-Ramasamy (SR) method under ambient conditions for the first time. The grown single crystal was subjected to different characterization analyses in order to find out its suitability for device fabrication. The crystalline perfection was evaluated using high-resolution X-ray diffractometry. It is evident from the optical absorption study that crystal has excellent transmission in the entire visible region with its lower cut off wavelength around 290 nm.

  20. Primary and secondary dendrite spacing of Ni-based superalloy single crystals

    Directory of Open Access Journals (Sweden)

    SLOBODANKA KOSTIC

    2009-01-01

    Full Text Available Ni-based superalloy single crystals were grown by different methods (gradient method and Bridgman technique with spontaneous nucleation and with seed. In all crystal growth experiments using the Bridgman technique, the temperature gradient along the vertical furnace axes was constant (G = 33.5 °C/cm. The obtained single crystals were cut, mechanical and chemical polished, and chemically etched. Using a metallographic microscope, the spacing of the primary and secondary dendrites was investigated. The dendrite arm spacing (DAS was determined using a Quantimet 500 MC. The obtained results are discussed and compared with published data.

  1. Single crystal growth of europium and ytterbium based intermetallic compounds using metal flux technique

    Indian Academy of Sciences (India)

    Sumanta Sarkar; Sebastian C Peter

    2012-11-01

    This article covers the use of indium as a potential metal solvent for the crystal growth of europium and ytterbium-based intermetallic compounds. A brief view about the advantage of metal flux technique and the use of indium as reactive and non-reactive flux are outlined. Large single crystals of EuGe2, EuCoGe3 and Yb2AuGe3 compounds were obtained in high yield from the reactions of the elements in liquid indium. The results presented here demonstrate that considerable advances in the discovery of single crystal growth of complex phases are achievable utilizing molten metals as solvents.

  2. Growth, structure, spectral properties and crystal-field analysis of monoclinic Nd:YNbO4 single crystal

    Science.gov (United States)

    Ding, Shoujun; Zhang, Qingli; Gao, Jinyun; Liu, Wenpeng; Luo, Jianqiao; Sun, Dunlu; Sun, Guihua; Wang, Xiaofei

    2016-12-01

    A Nd:YNbO4 single crystal was successfully grown by Czochralski (Cz) method, its structural and spectroscopic properties were investigated. The X-ray rocking curve of the (010) diffraction face of Nd:YNbO4 crystal was measured, the full width at half maximum (FWHM) of this diffraction peak is 0.05°, which indicates a high crystalline quality of the as-grown crystal. Its lattice parameters, atomic coordinates and so on were obtained by Rietvield refinement to X-ray diffraction data. According to the Archimedes drainage method, the crystal density of Nd:YNbO4 is calculated to be 5.4 g/cm3. The Mohr‧s hardness value along (010) face was determined to be 6.0. The transmission spectrum along (010) face at room temperature was recorded and the excitation and emission spectra at 8 K were measured. Photoluminescence peaks of Nd:YNbO4 were assigned, and the crystal-field splitting of Nd3+ in YNbO4 was obtained. The fluorescence lifetime of the 4F3/2→4I11/2 transition of Nd3+ in YNbO4 is fitted to be 152 μs These spectroscopic and energy splitting data give an important reference for the research of laser property of Nd:YNbO4 crystal.

  3. Growth, structure, spectral properties and crystal-field analysis of monoclinic Nd:YNbO{sub 4} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Shoujun [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Key Laboratory of Photonic Devices and Materials, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Zhang, Qingli, E-mail: zql@aiofm.ac.cn [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Key Laboratory of Photonic Devices and Materials, Hefei 230031 (China); Gao, Jinyun; Liu, Wenpeng; Luo, Jianqiao; Sun, Dunlu; Sun, Guihua; Wang, Xiaofei [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Key Laboratory of Photonic Devices and Materials, Hefei 230031 (China)

    2016-12-15

    A Nd:YNbO{sub 4} single crystal was successfully grown by Czochralski (Cz) method, its structural and spectroscopic properties were investigated. The X-ray rocking curve of the (010) diffraction face of Nd:YNbO{sub 4} crystal was measured, the full width at half maximum (FWHM) of this diffraction peak is 0.05°, which indicates a high crystalline quality of the as-grown crystal. Its lattice parameters, atomic coordinates and so on were obtained by Rietvield refinement to X-ray diffraction data. According to the Archimedes drainage method, the crystal density of Nd:YNbO{sub 4} is calculated to be 5.4 g/cm{sup 3}. The Mohr′s hardness value along (010) face was determined to be 6.0. The transmission spectrum along (010) face at room temperature was recorded and the excitation and emission spectra at 8 K were measured. Photoluminescence peaks of Nd:YNbO{sub 4} were assigned, and the crystal-field splitting of Nd{sup 3+} in YNbO{sub 4} was obtained. The fluorescence lifetime of the {sup 4}F{sub 3/2}→{sup 4}I{sub 11/2} transition of Nd{sup 3+} in YNbO{sub 4} is fitted to be 152 μs These spectroscopic and energy splitting data give an important reference for the research of laser property of Nd:YNbO{sub 4} crystal.

  4. CW frequency doubling of 1029 nm radiation Using single pass bulk and waveguide PPLN crystals

    CERN Document Server

    Chiodo, Nicola; Hrabina, Jan; Candela, Yves; Wallerand, Jean-Pierre; Acef, Ouali

    2013-01-01

    Following various works on second harmonic process using periodically poled Lithium Niobate crystals (PPLN), we report on the performances comparison between commercial bulk and waveguide crystals at 1029 nm. We use a continuous wave (CW) amplified Yb doped single fibre laser delivering up to 500mW in single mode regime. In case of bulk crystal we generate 4 mW using 400 mW IR power. The use of waveguide crystal leads to an increase of the harmonic power up to 33mW with input IR power limited to 200mW. Nevertheless, this impressive efficiency was affected by the long term degradation of the non-linear waveguide crystal.

  5. Thermal, FT–IR and dielectric studies of gel grown sodium oxalate single crystals

    Indian Academy of Sciences (India)

    B B Parekh; P M Vyas; Sonal R Vasant; M J Joshi

    2008-04-01

    Oxalic acid metabolism is important in humans, animals and plants. The effect of oxalic acid sodium salt is widely studied in living body. The growth of sodium oxalate single crystals by gel growth is reported, which can be used to mimic the growth of crystals in vivo. The grown single crystals are colourless, transparent and prismatic. The crystals have been characterized by thermogravimetric analysis, FT–IR spectroscopy and dielectric response at various frequencies of applied field. The crystals become anhydrous at 129.3°C. Coats and Redfern relation is applied to evaluate the kinetic and thermodynamic parameters of dehydration. The dielectric study suggests very less variation of dielectric constant with frequency of applied field in the range of 1 kHz–1 MHz. The nature of variation of imaginary part of complex permittivity, dielectric loss and a.c. resistivity with applied frequency has been reported.

  6. Self-cavity lasing in optically pumped single crystals of p-sexiphenyl

    Directory of Open Access Journals (Sweden)

    Hisao Yanagi

    2016-08-01

    Full Text Available Organic single-crystal self-cavities are prepared by solution growth of p-sexiphenyl (p-6P. Based on Fabry-Pérot feedback inside a quasi-lozenge-shaped platelet crystal, edge-emitting laser is obtained under optical pumping. The multimode lasing band appears at the 0-1 or 0-2 vibronic progressions depending on the excitation conditions which affect the self-absorption effect. Cavity-size dependence of amplified spontaneous emission (ASE is investigated with laser-etched single crystals of p-6P. As the cavity length of square-shaped crystal is reduced from 100 to 10 μm, ASE threshold fluence is decreased probably due to size-dependent light confinement in the crystal cavity.

  7. Growth of BPO 4 single crystals from Li 2O-MoO 3 flux

    Science.gov (United States)

    Zhang, Shufeng; Zhang, Erpan; Fu, Peizhen; Wu, Yicheng

    2009-04-01

    A new flux system, Li 2O-MoO 3, has been applied to growing BPO 4 single crystals. Transparent BPO 4 single crystals with sizes up to 31×18×16 mm 3 have been successfully grown from the new flux by the top-seeded solution growth method. The viscosity of solution using this new flux decreased significantly compared with that of previously utilized Li 4P 2O 7-Li 2O flux. The solubility was measured and favorable concentration for BPO 4 crystal growth was in the range of 55-64%. The powder SHG effect of as-grown BPO 4 crystal was observed and its intensity was about twice as large as that of KDP. The laser damage threshold of BPO 4 crystal at λ=1.064 nm and τ=8.0 ns is about 10.3 GW/cm 2.

  8. The influence of orientation on the stress rupture properties of nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Maier, R. D.

    1982-01-01

    Constant load creep rupture tests were performed on MAR-M247 single crystals at 724 MPa and 774 C where the effect of anisotropy is prominent. The initial orientations of the specimens as well as the final orientations of selected crystals after stress rupture testing were determined by the Laue back-reflection X-ray technique. The stress rupture lives of the MAR-M247 single crystals were found to be largely determined by the lattice rotations required to produce intersecting slip, because second-stage creep does not begin until after the onset of intersecting slip. Crystals which required large rotations to become oriented for intersecting slip exhibited the shortest stress rupture lives, whereas crystals requiring little or no rotations exhibited the lowest minimum creep rates, and consequently, the longest stress rupture lives.

  9. Synthesis, growth and characterization of L-Phenylalanine-4-nitrophenol (LPNP) single crystal

    Science.gov (United States)

    Rajalakshmi, M.; Indirajith, R.; Gopalakrishnan, R.

    2012-06-01

    Single crystals of L-Phenylalanine-4-nitrophenol (LPNP) were synthesis and grown by slow cooling solution growth technique. The grown crystals have been subjected to various characterization techniques such as single crystal X-ray diffraction and Powder X-ray diffraction studies to confirm the lattice parameters. Transmittance of the grown crystals was analysed and optical band gap calculated to be 1.54 eV. Thermogravimetric analysis and differential thermal analysis showed that the compound decomposes beyond 170°C. Mechanical behavior of the grown LPNP crystal was analyzed by Vicker's microhardness test. The relative second harmonic efficiency of the compound is found to be 0.3 greater than that of KDP.

  10. A microchip to analyze single crystal growth and size-controllability

    Institute of Scientific and Technical Information of China (English)

    PANG YuanFeng; LIU JiangJiang; LI HaiFang; LIN JinMing

    2009-01-01

    A microfluidic device to control single crystallization on the micron scale has been developed.The salt solution was stored in the nano-volume gaps between the arrays of protrudent circular plots in the microchip.The mixed organic solvent was injected into the chip as the counter diffusion phase for crystallization forming.This device provides a liquid-liquid interface through which only one phase flows while the other stays at the fixed plot.Therefore,it is possible to control the position of crystallization on the fixed plot.We can control the size and the uniformity of single crystals from 5 to 50 μm in length by adjusting the relative factors,such as interface lifetime,breeds of the mix-organic solvents and inject- ing velocities.The longer interface lifetime and lower organic solvent injecting velocities can bring up larger and more asymmetric crystals,which nearly shows the same trend compared with the macroscopic crystallization.Finally,the effect of the surfactant on the crystallization in the micro-device was studied.By adding the surfactant into the liquid-liquid interface,smaller sizes of crystals can be obtained without changing the crystal configuration.

  11. Inducing uniform single-crystal like orientation in natural rubber with constrained uniaxial stretch.

    Science.gov (United States)

    Zhou, Weiming; Meng, Lingpu; Lu, Jie; Wang, Zhen; Zhang, Wenhua; Huang, Ningdong; Chen, Liang; Li, Liangbin

    2015-07-07

    The effect of flow on crystallization is commonly attributed to entropic reduction, which is caused by stretch and orientation of polymer chains but overlooks the role of flow on final-state free energy. With the aid of in situ synchrotron radiation wide-angle X-ray diffraction (WAXD) and a homemade constrained uniaxial tensile testing machine, polycrystals possessing single-crystal-like orientation rather than uniaxial orientation are found during the constrained stretch of natural rubber, whereas the c-axis and a-axis align in the stretch direction (SD) and constrained direction (CD), respectively. Molecular dynamics simulation shows that aligning the a-axis of crystal nuclei in CD leads to the lowest free energy increase and favors crystal nucleation. This indicates that the nomenclature of strain-induced crystallization may not fully account for the nature of flow-induced crystallization (FIC) as strain mainly emphasizes the entropic reduction of initial melt, whereas stress rather than strain plays the dominant role in crystal deformation. The current work not only contributes to a comprehensive understanding of the mechanism of flow-induced crystallization but also demonstrates the potential application of constrained uniaxial tensile stretch for the creation of functional materials containing polycrystals that possess single-crystal-like orientation.

  12. Electronic microscopy analysis of HAP single crystals prepared by hydrothermal method

    Institute of Scientific and Technical Information of China (English)

    王友法; 闫玉华; 李美娟; 张宏泉

    2003-01-01

    H ydroxyapatite(HAP, Ca10 (PO4)6 (OH)2) is one of the quite important bone implant materials. Thehydroxyapatite crystals were synthesized under hydrothermal condition. The specimen was verified to be HAP crys-tal by the X-ray powder diffractometry(XRD). Then the specimen was distinguished single crystal from polycrystalby the use of the transmission electron microscope(TEM). The diffraction pattern of the specimen is neatly arrangeddiffraction spots, that verified the crystals were single crystals. The interplanar distance d calculated from diffrac-tion spot is coincided with that of HAP's JCPDS card. Moreover, crystal face angles calculated from crystal face in-dex are coincided with the values by measuring on the pattern. The HAP crystals are needle-like in shape with about3 μm in diameter and 180 μm in length. Most of the crystals are separate whiskers. Their length/diameter ratio ran-ges from 40 to 100. The average ratio is about 60.

  13. A microchip to analyze single crystal growth and size-controllability

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A microfluidic device to control single crystallization on the micron scale has been developed. The salt solution was stored in the nano-volume gaps between the arrays of protrudent circular plots in the microchip. The mixed organic solvent was injected into the chip as the counter diffusion phase for crystallization forming. This device provides a liquid-liquid interface through which only one phase flows while the other stays at the fixed plot. Therefore, it is possible to control the position of crystallization on the fixed plot. We can control the size and the uniformity of single crystals from 5 to 50 μm in length by adjusting the relative factors, such as interface lifetime, breeds of the mix-organic solvents and injecting velocities. The longer interface lifetime and lower organic solvent injecting velocities can bring up larger and more asymmetric crystals, which nearly shows the same trend compared with the macroscopic crystallization. Finally, the effect of the surfactant on the crystallization in the microdevice was studied. By adding the surfactant into the liquid-liquid interface, smaller sizes of crystals can be obtained without changing the crystal configuration.

  14. Orientation dependence of the stress rupture properties of Nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.

    1981-01-01

    The influence of orientation of the stress rupture behavior of Mar-M247 single crystals was studied. Stress rupture tests were performed at 724 MPa and 774 C where the effect of anisotropy is prominent. The mechanical behavior of the single crystals was rationalized on the basis of the Schmid factors for the operative slip systems and the lattice rotations which the crystals underwent during deformation. The stress rupture lives were found to be greatly influenced by the lattice rotations required to produce intersecting slip, because steady-state creep does not begin until after the onset of intersecting slip. Crystals which required large rotations to become oriented for intersecting slip exhibited a large primary creep strain, a large effective stress level at the onset of steady-state creep, and consequently a short stress rupture life. A unified analysis was attained for the stress rupture behavior of the Mar-M247 single crystals tested in this study at 774 C and that of the Mar-M200 single crystals tested in a prior study at 760 C. In this analysis, the standard 001-011-111 stereographic triangle was divided into several regions of crystallographic orientation which were rank ordered according to stress rupture life for this temperature regime. This plot indicates that those crystals having orientations within about 25 deg of the 001 exhibited significantly longer lives when their orientations were closer to the 001-011 boundary of the stereographic triangle than to the 001-111 boundary.

  15. Orientation dependence of the stress rupture properties of Nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.

    1981-05-01

    The influence of orientation of the stress rupture behavior of Mar-M247 single crystals was studied. Stress rupture tests were performed at 724 MPa and 774 C where the effect of anisotropy is prominent. The mechanical behavior of the single crystals was rationalized on the basis of the Schmid factors for the operative slip systems and the lattice rotations which the crystals underwent during deformation. The stress rupture lives were found to be greatly influenced by the lattice rotations required to produce intersecting slip, because steady-state creep does not begin until after the onset of intersecting slip. Crystals which required large rotations to become oriented for intersecting slip exhibited a large primary creep strain, a large effective stress level at the onset of steady-state creep, and consequently a short stress rupture life. A unified analysis was attained for the stress rupture behavior of the Mar-M247 single crystals tested in this study at 774 C and that of the Mar-M200 single crystals tested in a prior study at 760 C. In this analysis, the standard 001-011-111 stereographic triangle was divided into several regions of crystallographic orientation which were rank ordered according to stress rupture life for this temperature regime. This plot indicates that those crystals having orientations within about 25 deg of the 001 exhibited significantly longer lives when their orientations were closer to the 001-011 boundary of the stereographic triangle than to the 001-111 boundary.

  16. Thermal behaviour of helium-implanted spinel single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Velisa, G., E-mail: gihan@tandem.nipne.ro [National Institute for Physics and Nuclear Engineering - ' Horia Hulubei' , 407 Atomistilor St., P.O. Box MG-6, 077125 Magurele-Ilfov (Romania); Debelle, A. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, UMR8609, Bat. 108, 91405 Orsay (France); Vincent, L. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, UMR8609, Bat. 108, 91405 Orsay (France); Institut d' Electronique Fondamentale, Universite Paris-Sud, UMR8622, Bat. 220, 91405 Orsay (France); Thome, L. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, UMR8609, Bat. 108, 91405 Orsay (France); Declemy, A. [Institut Pprime, Departement de Physique et Mecanique des Materiaux, CNRS-Universite de Poitiers-ENSMA, BP 30179, 86962 Futuroscope-Chasseneuil Cedex (France); Pantelica, D. [National Institute for Physics and Nuclear Engineering - ' Horia Hulubei' , 407 Atomistilor St., P.O. Box MG-6, 077125 Magurele-Ilfov (Romania); Antohe, S. [Faculty of Physics, University of Bucharest, 405 Atomistilor, P.O. Box MG-11, 077125 Magurele-Ilfov (Romania)

    2011-09-01

    The study of the microstructural modifications induced in spinel implanted with {sup 4}He{sup +} at 4.7 at.% and subsequently annealed at 1075 K is addressed in this paper. The combination of three analysis techniques Rutherford backscattering spectrometry in channeling geometry (RBS/C), X-ray diffraction and transmission electron microscopy was used in order to gain information about the damage depth distribution, the nature of radiation defects, and the occurrence of microstructural modifications. In as-implanted crystals the disorder level is weak, and the damage principally consists of small helium-vacancy clusters. These defects induce a tensile strain in the direction normal to the implanted crystal surface. After annealing, a surprising increase of the disorder level is measured by RBS/C. This increased backscattering yield is due to the formation of a particular type of He-vacancy clusters, namely He platelets, which also induce a relaxation of the strain.

  17. Growth morphologies and optical properties of LTA single crystal.

    Science.gov (United States)

    Liu, Xiaojing; Ren, Miaojuan; Chen, Gang; Wang, Peiji

    2013-12-01

    Atomic force microscopy (AFM) has been used to study the growth morphologies of l-threonine acetate (abbreviated as LTA) crystal. Spiral growth hillocks and typical step patterns are described and discussed. Nuclei with various shapes often distribute at the larger step terraces. Eventually, in order to investigate microscopic second order nonlinear optical properties of LTA crystals, the molecular dipole moment (μ), polarizability (α), and first hyperpolarizability (β) were computed using a series of basis sets including polarized and diffuse functions at the framework of Hartree-Fock and density functional theory methods. The study is helpful to the further development of l-threonine analogs with improved nonlinear optical properties. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Pyroelectric properties and conduction mechanism in solution grown glycine sodium nitrate single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, Nidhi [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi 7 (India); Sinha, Nidhi [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi 7 (India); Department of Electronics, SGTB Khalsa College, University of Delhi, Delhi 7 (India); Yadav, Harsh [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi 7 (India); Kumar, Binay, E-mail: b3kumar69@yahoo.co.in [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi 7 (India)

    2015-04-01

    Nonlinear optical “glycine sodium nitrate” transparent single crystals were grown from aqueous solution by the solvent evaporation technique. The ferroelectric transition temperature was determined by dielectric measurement for GSN crystal. Temperature dependent pyroelectric coefficient and figure of merit were measured. The conduction mechanism of GSN crystal has been discussed. The ln σ−E{sup 1/2} characteristic in the high-field region supports dominating the Poole–Frenkel conduction while in the low field region; there are possibility of both Richardson–Schottky and Poole–Frenkel conduction mechanism. The activation energy of GSN crystal was found to be 0.58 eV. A low value of dielectric constant and good value of the figure of merit suggest the GSN crystal more promising for IR sensing applications. Hardness value shows the stability of GSN crystal.

  19. Raman Spectroscopy and Magnetic Properties of Mn-Doped ZnO Bulk Single Crystal

    Institute of Scientific and Technical Information of China (English)

    HE Qing-Bo; XU Jia-Yue; LI Xin-Hua; A.Kamzin; L.Kamzina

    2007-01-01

    Mn doped ZnO bulk single crystals are grown by the modified Bridgman method.The as-grown crystals are red in colour.The additional Raman mode observed at 524 cm-1 is attributed to the Mn ions incorporating into ZnO crystal.The crystal exhibited paramagnetic under lower applied fleld below 2280 Oe.Then diamagnetism is observed in the crystal when the magnetic field rises up and becomes dorainant under applied field above 5270 Oe.The magnetic susceptibility dependence on the temperature follows a Curie law indicating a typical paramagnetic characteristic under an applied field of 2kOe.No ferromagnetic ordering is observed in the as-grown Mn-doped ZnO crystal.

  20. Growth of L-Valinium Aluminium Chloride single crystal for OLED and super-capacitor applications

    Science.gov (United States)

    Kalaivani, D.; Vijayalakshmi, S.; Theras, J. Elberin Mary; Jayaraman, D.; Joseph, V.

    2015-12-01

    L-Valinium Aluminium Chloride (LVAC), a novel semi-organic material, was grown using slow evaporation under isothermal condition. The single crystal data reveal that the grown crystal belongs to monoclinic system. The SEM micrographs give clear picture about the surface morphology. Further, they confirm the inclusion of aluminium chloride into atomic sites of L-Valine. The compositional elements present in the crystal were identified through EDAX analysis. The mass spectral analysis was carried out to determine the molecular weight of the grown crystal. The optical transparency of the grown crystal was investigated by UV-vis-NIR spectrum. FTIR spectral study was used to identify the functional groups present in the grown material. The luminescence characteristics of grown material were analysed to confirm the effect of metal ion on the ligand. This property makes the material suitable for OLED application. The supercapacitive performance of the grown crystal was finally studied using cyclic voltammetry.