Single crystal and optical ceramic multicomponent garnet scintillators: A comparative study

International Nuclear Information System (INIS)

Wu, Yuntao; Luo, Zhaohua; Jiang, Haochuan; Meng, Fang; Koschan, Merry; Melcher, Charles L.

2015-01-01

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 3 Ga 3 Al 2 O 12 :0.2 at% Ce (GGAG:Ce) single crystal and (Gd,Lu) 3 Ga 3 Al 2 O 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 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 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 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 multicomponent aluminate garnets are discussed

Spherical Nb single crystals containerlessly grown by electrostatic levitation

International Nuclear Information System (INIS)

Sung, Y.S.; Takeya, H.; Hirata, K.; Togano, K.

2003-01-01

Spherical Nb (T m =2750 K) single crystals were grown via containerless electrostatic levitation (ESL). Samples became spherical at melting in levitation and undercooled typically 300-450 K prior to nucleation. As-processed samples were still spherical without any macroscopic shape change by solidification showing a uniform dendritic surface morphology. Crystallographic {111} planes exposed in equilateral triangular shapes on the surface by preferential macroetching and spotty back-reflection Laue patterns confirm the single crystal nature of the ESL-processed Nb samples. No hysteresis in magnetization between zero field and field cooling also implies a clean defect-free condition of the spherical Nb single crystals

Photoconversion of F+ centers in neutron-irradiated MgO

International Nuclear Information System (INIS)

Monge, M.A.; Gonzalez, R.; Munoz Santiuste, J.E.; Pareja, R.; Chen, Y.; Kotomin, E.A.; Popov, A.I.

2000-01-01

In neutron-irradiated MgO crystals, experiments and theory demonstrate that photon excitation of the positively charged anion vacancies (F + centers) at 5.0 eV releases holes that are subsequently trapped at V-type centers, which are cation vacancies charge-compensated by impurities, such as Al 3+ , F - , and OH - ions. A photoconversion mechanism occurs very likely via electron transfer to F + centers from the quasi-local states which are induced in the valence band. INDO quantum chemical simulations of F + centers confirmed the appearance of two induced quasi-local states located at 1.2 and 2.0 eV below the top of the valence band

Metal Halide Perovskite Single Crystals: From Growth Process to Application

Directory of Open Access Journals (Sweden)

Shuigen Li

2018-05-01

Full Text Available As a strong competitor in the field of optoelectronic applications, organic-inorganic metal hybrid perovskites have been paid much attention because of their superior characteristics, which include broad absorption from visible to near-infrared region, tunable optical and electronic properties, high charge mobility, long exciton diffusion length and carrier recombination lifetime, etc. It is noted that perovskite single crystals show remarkably low trap-state densities and long carrier diffusion lengths, which are even comparable with the best photovoltaic-quality silicon, and thus are expected to provide better optoelectronic performance. This paper reviews the recent development of crystal growth in single-, mixed-organic-cation and fully inorganic halide perovskite single crystals, in particular the solution approach. Furthermore, the application of metal hybrid perovskite single crystals and future perspectives are also highlighted.

Anisotropy of Single-Crystal Silicon in Nanometric Cutting.

Science.gov (United States)

Wang, Zhiguo; Chen, Jiaxuan; Wang, Guilian; Bai, Qingshun; Liang, Yingchun

2017-12-01

The anisotropy exhibited by single-crystal silicon in nanometric cutting is very significant. In order to profoundly understand the effect of crystal anisotropy on cutting behaviors, a large-scale molecular dynamics model was conducted to simulate the nanometric cutting of single-crystal silicon in the (100)[0-10], (100)[0-1-1], (110)[-110], (110)[00-1], (111)[-101], and (111)[-12-1] crystal directions in this study. The simulation results show the variations of different degrees in chip, subsurface damage, cutting force, and friction coefficient with changes in crystal plane and crystal direction. Shear deformation is the formation mechanism of subsurface damage, and the direction and complexity it forms are the primary causes that result in the anisotropy of subsurface damage. Structurally, chips could be classified into completely amorphous ones and incompletely amorphous ones containing a few crystallites. The formation mechanism of the former is high-pressure phase transformation, while the latter is obtained under the combined action of high-pressure phase transformation and cleavage. Based on an analysis of the material removal mode, it can be found that compared with the other crystal direction on the same crystal plane, the (100)[0-10], (110)[-110], and (111)[-101] directions are more suitable for ductile cutting.

Electronic structure and orientation relationship of Li nanoclusters embedded in MgO studied by depth-selective positron annihilation two-dimensional angular correlation

Science.gov (United States)

Falub, C. V.; Mijnarends, P. E.; Eijt, S. W.; van Huis, M. A.; van Veen, A.; Schut, H.

2002-08-01

Quantum-confined positrons are sensitive probes for determining the electronic structure of nanoclusters embedded in materials. In this work, a depth-selective positron annihilation 2D-ACAR (two-dimensional angular correlation of annihilation radiation) method is used to determine the electronic structure of Li nanoclusters formed by implantation of 1016-cm-2 30-keV 6Li ions in MgO (100) and (110) crystals and by subsequent annealing at 950 K. Owing to the difference between the positron affinities of lithium and MgO, the Li nanoclusters act as quantum dots for positrons. 2D-ACAR distributions for different projections reveal a semicoherent fitting of the embedded metallic Li nanoclusters to the host MgO lattice. Ab initio Korringa-Kohn-Rostoker calculations of the momentum density show that the anisotropies of the experimental distributions are consistent with an fcc crystal structure of the Li nanoclusters. The observed reduction of the width of the experimental 2D-ACAR distribution is attributed to positron trapping in vacancies associated with Li clusters. This work proposes a method for studying the electronic structure of metallic quantum dots embedded in an insulating material.

Neutron transmission measurements of zinc and lead single crystals

International Nuclear Information System (INIS)

Adib, M.; Abdel-Kawy, A.

1988-01-01

Neutron transmission measurements of zinc and lead single crystals have been carried out in a neutron wavelength band from 0.03 to 0.55 nm at different orientations of the crystal with regard to the beam direction. The measurements were performed using both time-of-flight and fixed-angle scattering spectrometers installed in front of the ET-RR-1 reactor horizontal channels. It was found that the position of the observed dips in the neutron transmission measurements corresponded to the reflections from the (h k l) planes of the hexagonal zinc single crystal which was cut along the (0 0 2) plane, while in the case of lead, the single crystal was cut perpendicular to the (3 1 1) plane. The reflectivity from the (0 0 2) plane of zinc was determined using both transmission and reflection methods. The maximum reflectivity was found to be 55% when the zinc crystal was orientated at 45 0 to the beam direction. The wavelength spread of the observed reflectivity curve was found to be in agreement with the calculated one, taking into consideration the spectrometer's resolution and the crystal mosaic spread. (author)

Bulk and surface properties of magnesium peroxide MgO2

Science.gov (United States)

Esch, Tobit R.; Bredow, Thomas

2016-12-01

Magnesium peroxide has been identified in Mg/air batteries as an intermediate in the oxygen reduction reaction (ORR) [1]. It is assumed that MgO2 is involved in the solid-electrolyte interphase on the cathode surface. Therefore its structure and stability play a crucial role in the performance of Mg/air batteries. In this work we present a theoretical study of the bulk and low-index surface properties of MgO2. All methods give a good account of the experimental lattice parameters for MgO2 and MgO bulk. The reaction energies, enthalpies and free energies for MgO2 formation from MgO are compared among the different DFT methods and with the local MP2 method. A pronounced dependence from the applied functional is found. At variance with a previous theoretical study but in agreement with recent experiments we find that the MgO2 formation reaction is endothermic (HSE06-D3BJ: ΔH = 51.9 kJ/mol). The stability of low-index surfaces MgO2 (001) (Es = 0.96 J/m2) and (011) (Es = 1.98 J/m2) is calculated and compared to the surface energy of MgO (001). The formation energy of neutral oxygen vacancies in the topmost layer of the MgO2 (001) surface is calculated and compared with defect formation energies for MgO (001).

Theoretical Limiting Potentials in Mg/O2 Batteries

DEFF Research Database (Denmark)

Smith, Jeffrey G.; Naruse, Junichi; Hiramatsu, Hidehiko

2016-01-01

A rechargeable battery based on a multivalent Mg/O2 couple is an attractive chemistry due to its high theoretical energy density and potential for low cost. Nevertheless, metal-air batteries based on alkaline earth anodes have received limited attention and generally exhibit modest performance....... In addition, many fundamental aspects of this system remain poorly understood, such as the reaction mechanisms associated with discharge and charging. The present study aims to close this knowledge gap and thereby accelerate the development of Mg/O2 batteries by employing first-principles calculations...... by the presence of large thermodynamic overvoltages. In contrast, MgO2-based cells are predicted to be much more efficient: superoxide-terminated facets on MgO2 crystallites enable low overvoltages and round-trip efficiencies approaching 90%. These data suggest that the performance of Mg/O2 batteries can...

Crystal growth, spectroscopic characterization and laser performance of Tm/Mg:LiNbO3 crystal

Science.gov (United States)

Zhang, P. X.; Yin, J. G.; Zhang, R.; Li, H. Q.; Xu, J. Q.; Hang, Y.

2014-03-01

A Tm, Mg co-doped LiNbO3 crystal was grown by the traditional Czochralski method. The room-temperature absorption, photo-luminescence spectra and fluorescence lifetime of Tm3+ ions in the crystal have been investigated. The experimental results show that the co-doped of MgO can lead to the lengthening of the measured fluorescence lifetime of the upper Tm3+:3F4 level. Based on the Judd-Ofelt approach, the intensity parameters Ω2,4,6 of Tm3+ were calculated to be Ω2 (6.29 × 10-20 cm2), Ω4 (0.54 × 10-20 cm2) and Ω6 (0.79 × 10-20 cm2). Other spectroscopic parameters that relate to laser performance were also obtained. Non-photorefractive continuous wave laser operation with a Tm, Mg:LiNbO3 single crystal is demonstrated at room temperature for the first time. We obtained 1.026 W output power at 1.885 μm with a slope efficiency of near 14%, which, to the best of our knowledge, is the largest output power and the highest slope efficiency obtained for this crystal thus far. The output power was observed to be stable, and the crystal showed no sign of photorefractive damage.

Single-Crystal Diamond Nanobeam Waveguide Optomechanics

Science.gov (United States)

Khanaliloo, Behzad; Jayakumar, Harishankar; Hryciw, Aaron C.; Lake, David P.; Kaviani, Hamidreza; Barclay, Paul E.

2015-10-01

Single-crystal diamond optomechanical devices have the potential to enable fundamental studies and technologies coupling mechanical vibrations to both light and electronic quantum systems. Here, we demonstrate a single-crystal diamond optomechanical system and show that it allows excitation of diamond mechanical resonances into self-oscillations with amplitude >200 nm . The resulting internal stress field is predicted to allow driving of electron spin transitions of diamond nitrogen-vacancy centers. The mechanical resonances have a quality factor >7 ×105 and can be tuned via nonlinear frequency renormalization, while the optomechanical interface has a 150 nm bandwidth and 9.5 fm /√{Hz } sensitivity. In combination, these features make this system a promising platform for interfacing light, nanomechanics, and electron spins.

Raman scattering from epitaxial HfN layers grown on MgO(001)

International Nuclear Information System (INIS)

Stoehr, M.; Seo, H.-S.; Petrov, I.; Greene, J.E.

2006-01-01

Stoichiometric single-crystal HfN layers grown on MgO(001) are analyzed by Raman spectroscopy. Second-order Raman scattering predominates, but first-order modes in the acoustic and optical ranges are also visible. The latter indicates that the O h symmetry of NaCl-structure HfN is broken. The large mass difference between Hf and N leads to a correspondingly large separation, 250 cm -1 , between the first-order acoustic and optical bands. Within this gap, four Raman lines are clearly observed. The first three are the second-order transverse acoustic mode (240 cm -1 ), the sum of the first-order transverse and longitudinal acoustic modes (280 cm -1 ), and the second-order longitudinal acoustic mode (325 cm -1 ). The fourth line at 380 cm -1 is identified as the difference between the first-order optical and acoustic modes. The observed first-order Raman scattering, as well as the width of the gap between the first-order acoustic and optical modes, is in good agreement with previously calculated HfN phonon density of states

Registration of interstitial anions in irradiated MgO crystals

International Nuclear Information System (INIS)

Surzhikov, A.P.; Pogrebnyak, A.D.

1985-01-01

Possibility of application of positron annihilation for detection in oxides of rare earth metals with interstitial component of Frenkel anion defects is revealed. Magnesium oxide monocrystals with Ca, Si, Fe, Al impurity contents of 0.1 wt.% were investigated. These crystals were irradiated by X-rays (45 kV, 20 μA) and protons (10 MeV). It is shown that heating of magnesium oxide crystals irradiated by protons up to 700 K completely anneals F + -centers. In this case the component disappears inth the pulse distributon at xi=5.0; the subsequent crystal irradiation with X-ray does not lead to its reduction

Seeded growth of boron arsenide single crystals with high thermal conductivity

Science.gov (United States)

Tian, Fei; Song, Bai; Lv, Bing; Sun, Jingying; Huyan, Shuyuan; Wu, Qi; Mao, Jun; Ni, Yizhou; Ding, Zhiwei; Huberman, Samuel; Liu, Te-Huan; Chen, Gang; Chen, Shuo; Chu, Ching-Wu; Ren, Zhifeng

2018-01-01

Materials with high thermal conductivities are crucial to effectively cooling high-power-density electronic and optoelectronic devices. Recently, zinc-blende boron arsenide (BAs) has been predicted to have a very high thermal conductivity of over 2000 W m-1 K-1 at room temperature by first-principles calculations, rendering it a close competitor for diamond which holds the highest thermal conductivity among bulk materials. Experimental demonstration, however, has proved extremely challenging, especially in the preparation of large high quality single crystals. Although BAs crystals have been previously grown by chemical vapor transport (CVT), the growth process relies on spontaneous nucleation and results in small crystals with multiple grains and various defects. Here, we report a controllable CVT synthesis of large single BAs crystals (400-600 μm) by using carefully selected tiny BAs single crystals as seeds. We have obtained BAs single crystals with a thermal conductivity of 351 ± 21 W m-1 K-1 at room temperature, which is almost twice as conductive as previously reported BAs crystals. Further improvement along this direction is very likely.

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.

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.

Atomic structures and mechanical properties of single-crystal GaN nanotubes

International Nuclear Information System (INIS)

Xu, B.; Lu, A.J.; Pan, B.C.; Yu, Q.X.

2005-01-01

An approach is proposed to theoretically construct a realistic single-crystal GaN nanotube at atomic scale. The generated atomic structures of the single-crystal GaN nanotubes match the structural aspects from experiment very well. Our energetic calculations show that a single-crystal GaN nanotube with [100]-oriented lateral facets is more stable than that with [110]-oriented lateral facets, when they have around the same wall thickness. For a specified orientation of the lateral facets on the single-crystal GaN nanotubes, the energetic stabilities of the tubes obey a P rule, in which P is the ratio of the number of four-coordinated atoms to the number of three-coordinated atoms. Furthermore, the Young's modulus of the considered GaN nanotubes decrease with increasing the ratio of the number of bulk atoms to the number of surface atoms in each type of tube. Our calculations and analysis demonstrate that the surface effect of a single-crystal nanotube enhances its Young's modulus significantly

Growth and characterization of nonlinear optical single crystal: Nicotinic L-tartaric

Energy Technology Data Exchange (ETDEWEB)

Sheelarani, V.; Shanthi, J., E-mail: shanthinelson@gmail.com [Department of Physics, Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore-641043 (India)

2015-06-24

Nonlinear optical single crystals were grown from Nicotinic and L-Tartaric acid by slow evaporation technique at room temperature. Structure of the grown crystal was confirmed by single crystal X-ray diffraction studies, The crystallinity of the Nicotinic L-Tartaric (NLT) crystals was confirmed from the powder XRD pattern. The transparent range and cut off wavelength of the grown crystal was studied by the UV–Vis spectroscopic analysis.The thermal stability of the crystal was studied by TG-DTA. The second harmonic generation (SHG) efficiency of NLT was confirmed by Kurtz Perry technique.

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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrothermal growth of PbSO4 (Anglesite) single crystal

International Nuclear Information System (INIS)

Kikuta, Ko-ichi; Yoneta, Yasuhito; Yogo, Toshinobu; Hirano, Shin-ichi

1994-01-01

Hydrothermal growth of single crystals of PbSO 4 , which is known as a natural mineral called anglesite, was investigated. Lead nitrate and nitric acid solutions were found to be useful for the growth of angle-site on the basis of the experimental results on the dissolution behavior. Relatively large euhedral single crystals bound by {210} and {101} planes were successfully grown in 1.5 mol/kg Pb(NO 3 ) 2 at 400degC and 100 MPa. Optical characterization revealed that the grown anglesite crystals can be useful for scintillators material. (author)

Complete sets of elastic constants and photoelastic coefficients of pure and MgO-doped lithium niobate crystals at room temperature

International Nuclear Information System (INIS)

Andrushchak, A. S.; Laba, H. P.; Yurkevych, O. V.; Mytsyk, B. G.; Solskii, I. M.; Kityk, A. V.; Sahraoui, B.

2009-01-01

This paper presents the results of ultrasonic measurements of LiNbO 3 and LiNbO 3 :MgO crystals. The tensors of piezoelectric coefficients, elastic stiffness constants, and elastic compliances are determined for both crystals at room temperature. Combining these data with the results of piezo-optical measurements, a complete set of photoelastic tensor coefficients is also calculated. Doping of LiNbO 3 crystals by MgO does not lead to a considerable modification of their elastic and photoelastic properties. However, LiNbO 3 :MgO is characterized by a considerably higher resistance with respect to powerful light radiation, making it promising for future application in acousto-optic devices that deal with superpowerful laser radiation. Presented here are the complete tensor sets of elastic constants and photoelastic coefficients of LiNbO 3 and LiNbO 3 :MgO crystals that may be used for a geometry optimization of acousto-optical interaction providing the best diffraction efficiency of acousto-optical cells made of these materials.

Crystal growth and characterization of a semiorganic nonlinear optical single crystal of gamma glycine

International Nuclear Information System (INIS)

Prakash, J. Thomas Joseph; Kumararaman, S.

2008-01-01

Gamma glycine has been successfully synthesized by taking glycine and potassium chloride and single crystals have been grown by solvent evaporation method for the first time. The grown single crystals have been analyzed with XRD, Fourier transform infrared (FTIR), and thermo gravimetric and differential thermal analyses (TG/DTA) measurements. Its mechanical behavior has been assessed by Vickers microhardness measurements. Its nonlinear optical property has been tested by Kurtz powder technique. Its optical behavior was examined by UV-vis., and found that the crystal is transparent in the region between 240 and 1200 nm. Hence, it may be very much useful for the second harmonic generation (SHG) applications

Growth of single crystals from solutions using semi-permeable membranes

Science.gov (United States)

Varkey, A. J.; Okeke, C. E.

1983-05-01

A technique suitable for growth of single crystals from solutions using semi-preamble membranes is described. Using this technique single crystals of copper sulphate, potassium bromide and ammonium dihydrogen phosphate have been successfully grown. Advantages of this technique over other methods are discussed.

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

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 p-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

Light emission from organic single crystals operated by electrolyte doping

Science.gov (United States)

Matsuki, Keiichiro; Sakanoue, Tomo; Yomogida, Yohei; Hotta, Shu; Takenobu, Taishi

2018-03-01

Light-emitting devices based on electrolytes, such as light-emitting electrochemical cells (LECs) and electric double-layer transistors (EDLTs), are solution-processable devices with a very simple structure. Therefore, it is necessary to apply this device structure into highly fluorescent organic materials for future printed applications. However, owing to compatibility problems between electrolytes and organic crystals, electrolyte-based single-crystal light-emitting devices have not yet been demonstrated. Here, we report on light-emitting devices based on organic single crystals and electrolytes. As the fluorescent materials, α,ω-bis(biphenylyl)terthiophene (BP3T) and 5,6,11,12-tetraphenylnaphthacene (rubrene) single crystals were selected. Using ionic liquids as electrolytes, we observed clear light emission from BP3T LECs and rubrene EDLTs.

Parasitic neutron bragg reflections from large imperfect single crystals

Energy Technology Data Exchange (ETDEWEB)

Naguib, K.; Adib, M

1998-12-01

A formula is given which allows to calculate the contribution of the total Bragg scattering from different (hkl) planes to the neutron transmission through a large imperfect single crystals. The formula takes into account the crystal structure type, its mosaic spread value, the plane along which the crystal surface is cut along and its orientation with respect to the neutron beam direction. A computer program ISCANF-1 was developed to calculate the total parasitic scattering cross-section from different (hkl) planes as well as the nuclear and diffuse scattering cross-sections. The ISCANF-1 program was applied to calculate the neutron attenuation through Cu and Zn single crystals, each of them cut along (002) planes. The calculated values of the neutron transmission through Cu and Zn crystals were compared with the measured ones in the wavelength range 0.21-0.47 nm and 0.04-0.52 nm respectively. The measured and calculated values were found to be in reasonable agreement within the statistical accuracy. The computer program ISCANF-1 was also applied to investigate the effect of parasitic Bragg scattering on the neutron filtering characteristics of both Zn and Cu single crystals as a function of their physical parameters.

Parasitic neutron bragg reflections from large imperfect single crystals

International Nuclear Information System (INIS)

Naguib, K.; Adib, M.

1998-01-01

A formula is given which allows to calculate the contribution of the total Bragg scattering from different (hkl) planes to the neutron transmission through a large imperfect single crystals. The formula takes into account the crystal structure type, its mosaic spread value, the plane along which the crystal surface is cut along and its orientation with respect to the neutron beam direction. A computer program ISCANF-1 was developed to calculate the total parasitic scattering cross-section from different (hkl) planes as well as the nuclear and diffuse scattering cross-sections. The ISCANF-1 program was applied to calculate the neutron attenuation through Cu and Zn single crystals, each of them cut along (002) planes. The calculated values of the neutron transmission through Cu and Zn crystals were compared with the measured ones in the wavelength range 0.21-0.47 nm and 0.04-0.52 nm respectively. The measured and calculated values were found to be in reasonable agreement within the statistical accuracy. The computer program ISCANF-1 was also applied to investigate the effect of parasitic Bragg scattering on the neutron filtering characteristics of both Zn and Cu single crystals as a function of their physical parameters

Growth and microtopographic study of CuInSe{sub 2} single crystals

Energy Technology Data Exchange (ETDEWEB)

Chauhan, Sanjaysinh M.; Chaki, Sunil, E-mail: sunilchaki@yahoo.co.in; Deshpande, M. P. [Department of Physics, Sardar Patel University, Vallabh Vidyanagar, Gujarat - 388120 (India); Tailor, J. P. [Applied Physics Department, S.V.N.I.T., Surat, Gujarat - 395007 (India)

2016-05-23

The CuInSe{sub 2} single crystals were grown by chemical vapour transport (CVT) technique using iodine as transporting agent. The elemental composition of the as-grown CuInSe{sub 2} single crystals was determined by energy dispersive analysis of X-ray (EDAX). The unit cell crystal structure and lattice parameters were determined by X-ray diffraction (XRD) technique. The surface microtopographic study of the as-grown CuInSe{sub 2} single crystals surfaces were done to study the defects, growth mechanism, etc. of the CVT grown crystals.

Mechanical properties of hydroxyapatite single crystals from nanoindentation data

Science.gov (United States)

Zamiri, A.; De, S.

2011-01-01

In this paper we compute elasto-plastic properties of hydroxyapatite single crystals from nanindentation data using a two-step algorithm. In the first step the yield stress is obtained using hardness and Young’s modulus data, followed by the computation of the flow parameters. The computational approach is first validated with data from existing literature. It is observed that hydroxyapatite single crystals exhibit anisotropic mechanical response with a lower yield stress along the [1010] crystallographic direction compared to the [0001] direction. Both work hardening rate and work hardening exponent are found to be higher for indentation along the [0001] crystallographic direction. The stress-strain curves extracted here could be used for developing constitutive models for hydroxyapatite single crystals. PMID:21262492

Single-Crystal Diamond Nanobeam Waveguide Optomechanics

Directory of Open Access Journals (Sweden)

Behzad Khanaliloo

2015-12-01

Full Text Available Single-crystal diamond optomechanical devices have the potential to enable fundamental studies and technologies coupling mechanical vibrations to both light and electronic quantum systems. Here, we demonstrate a single-crystal diamond optomechanical system and show that it allows excitation of diamond mechanical resonances into self-oscillations with amplitude >200  nm. The resulting internal stress field is predicted to allow driving of electron spin transitions of diamond nitrogen-vacancy centers. The mechanical resonances have a quality factor >7×10^{5} and can be tuned via nonlinear frequency renormalization, while the optomechanical interface has a 150 nm bandwidth and 9.5  fm/sqrt[Hz] sensitivity. In combination, these features make this system a promising platform for interfacing light, nanomechanics, and electron spins.

Ordered macro-microporous metal-organic framework single crystals

KAUST Repository

Shen, Kui

2018-01-16

We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional-ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent-induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

Ordered macro-microporous metal-organic framework single crystals

Science.gov (United States)

Shen, Kui; Zhang, Lei; Chen, Xiaodong; Liu, Lingmei; Zhang, Daliang; Han, Yu; Chen, Junying; Long, Jilan; Luque, Rafael; Li, Yingwei; Chen, Banglin

2018-01-01

We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional–ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent–induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

Ordered macro-microporous metal-organic framework single crystals

KAUST Repository

Shen, Kui; Zhang, Lei; Chen, Xiaodong; Liu, Lingmei; Zhang, Daliang; Han, Yu; Chen, Junying; Long, Jilan; Luque, Rafael; Li, Yingwei; Chen, Banglin

2018-01-01

We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional-ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent-induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

Multifunctional MgO Layer in Perovskite Solar Cells.

Science.gov (United States)

Guo, Xudong; Dong, Haopeng; Li, Wenzhe; Li, Nan; Wang, Liduo

2015-06-08

A multifunctional magnesium oxide (MgO) layer was successfully introduced into perovskite solar cells (PSCs) to enhance their performance. MgO was coated onto the surface of mesoporous TiO(2) by the decomposition of magnesium acetate and, therefore, could block contact between the perovskite and TiO(2). X-ray photoelectron spectroscopy and infrared spectroscopy showed that the amount of H(2)O/hydroxyl absorbed on the TiO(2) decreased after MgO modification. The UV/Vis absorption spectra of the perovskite with MgO modification revealed an enhanced photoelectric performance compared with that of unmodified perovskite after UV illumination. In addition to the photocurrent, the photovoltage and fill factor also showed an enhancement after modification, which resulted in an increase in the overall efficiency of the cell from 9.6 to 13.9 %. Electrochemical impedance spectroscopy (EIS) confirmed that MgO acts as an insulating layer to reduce charge recombination. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single-crystal-to-single-crystal transformation and solvochromic luminescence of a dinuclear gold(I)-(aza-[18]crown-6)dithiocarbamate compound.

Science.gov (United States)

Tzeng, Biing-Chiau; Chao, An

2015-01-26

The treatment of [AuCl(SMe2 )] with an equimolar amount of NaO5 NCS2 (O5 NCS2 =(aza-[18]crown-6)dithiocarbamate) in CH3 CN gave [Au2 (O5 NCS2 )2 ]⋅2 CH3 CN (2⋅2 CH3 CN), and its crystal structure displays a dinuclear gold(I)-azacrown ether ring and an intermolecular gold(I)⋅⋅⋅gold(I) contact of 2.8355(3) Å in crystal lattices. It is noted that two other single crystals of 2⋅tert-butylbenzene⋅H2 O and 2⋅0.5 m-xylene can be successfully obtained from a single-crystal-to-single-crystal (SCSC) transformation process by immersing single crystals of 2⋅2 CH3 CN in the respective solvents, and both also show intermolecular gold(I)⋅⋅⋅gold(I) contacts of 2.9420(5) and 2.890(2)-2.902(2) Å, respectively. Significantly, the emissions of all three 2⋅solvates are well correlated with their respective intermolecular gold(I)⋅⋅⋅gold(I) contacts, where such contacts increase with 2⋅2 CH3 CN (2.8355(3) Å)energies increase with 2⋅2 CH3 CN (602 nm)<2⋅0.5 m-xylene (583 nm)<2⋅tert-butylbenzene⋅H2 O (546 nm) as well. In this regard, we further examine the solvochromic luminescence for some other aromatics, and finally their emissions are within 546-602 nm. Obviously, the above results are mostly ascribed to the occurrence of intermolecular gold(I)⋅⋅⋅gold(I) contacts in 2⋅solvates, which are induced by the presence of various solvates in the solid state, as a key role to be responsible for their solvochromic luminescence. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The influence of mineralogical, chemical and physical properties on grindability of commercial clinkers with high MgO level

International Nuclear Information System (INIS)

Souza, Vladia Cristina G. de; Koppe, Jair Carlos; Costa, Joao F.C.L.; Vargas, Andre Luis Marin; Blando, Eduardo; Huebler, Roberto

2008-01-01

This research investigates various methods able to identify possible mineralogical, physical and chemical influences on the grindability of commercial clinkers with high MgO level. The aim of the study is to evaluate the hardness and elastic modulus of the clinker mineral phases and their fracture strength during the comminution processes, comparing samples from clinkers with low MgO level (0.5%) and clinkers with elevated MgO levels (> 5.0%). The study of the influence of mineralogical, chemical and physical properties was carried out using several analytical techniques, such as: optical microscopy, X-ray diffraction with Rietveld refinement (XRD) and X-ray fluorescence (XRF). These techniques were useful in qualifying the different clinker samples. The drop weight test (DWT) and the Bond ball mill grindability test were performed to characterize the mechanical properties of clinkers. Nanoindentation tests were also carried out. Results from the Bond ball mill grindability test were found to be related to the hardness of the mineral phase and to mineralogical characteristics, such as type and amount of inclusions in silicates, belite and alite crystals shape, or microcracked alites. In contrast, the results obtained by the DWT were associated to the macro characteristics of clinkers, such as porosity, as well as to the hardness and mineralogical characteristics of belite crystals in clusters. Hardness instrumented tests helped to determine the Vickers hardness and elastic modulus from the mineral phases in commercial clinkers and produced different values for the pure phases compared to previous publications

Mesoscale martensitic transformation in single crystals of topological defects

Energy Technology Data Exchange (ETDEWEB)

Li, Xiao; Martínez-González, José A.; Hernández-Ortiz, Juan P.; Ramírez-Hernández, Abelardo; Zhou, Ye; Sadati, Monirosadat; Zhang, Rui; Nealey, Paul F.; de Pablo, Juan J.

2017-09-05

Liquid crystal blue phases (BPs) are highly ordered at two levels. Molecules exhibit orientational order at nanometer length scales, while chirality leads to ordered arrays of doubletwisted cylinders over micrometer scales. Past studies of polycrystalline BPs were challenged by grain boundaries between randomly oriented crystalline nanodomains. Here, the nucleation of BPs is controlled with considerable precision by relying on chemically nano-patterned surfaces, leading to macroscopic single-crystal BP specimens where the dynamics of meso-crystal formation can be directly observed. Theory and experiments show that transitions between two BPs having a different network structure proceed through local re-organization of the crystalline array, without diffusion of the double twisted cylinders. In solid crystals, martensitic transformations between crystal structures involve the concerted motion of a few atoms, without diffusion. The transformation between BPs, where crystal features arise in the sub-micron regime, is found to be martensitic in nature, with the diffusion-less feature associated to the collective behavior of the double twist cylinders. Single-crystal BPs are shown to offer fertile grounds for the study of directed crystal-nucleation and the controlled growth of soft matter.

Effect of Chain Conformation on the Single-Molecule Melting Force in Polymer Single Crystals: Steered Molecular Dynamics Simulations Study.

Science.gov (United States)

Feng, Wei; Wang, Zhigang; Zhang, Wenke

2017-02-28

Understanding the relationship between polymer chain conformation as well as the chain composition within the single crystal and the mechanical properties of the corresponding single polymer chain will facilitate the rational design of high performance polymer materials. Here three model systems of polymer single crystals, namely poly(ethylene oxide) (PEO), polyethylene (PE), and nylon-66 (PA66) have been chosen to study the effects of chain conformation, helical (PEO) versus planar zigzag conformation (PE, PA66), and chain composition (PE versus PA66) on the mechanical properties of a single polymer chain. To do that, steered molecular dynamics simulations were performed on those polymer single crystals by pulling individual polymer chains out of the crystals. Our results show that the patterns of force-extension curve as well as the chain moving mode are closely related to the conformation of the polymer chain in the single crystal. In addition, hydrogen bonds can enhance greatly the force required to stretch the polymer chain out of the single crystal. The dynamic breaking and reformation of multivalent hydrogen bonds have been observed for the first time in PA66 at the single molecule level.

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-11-15

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

High definition TV projection via single crystal faceplate technology

Science.gov (United States)

Kindl, H. J.; St. John, Thomas

1993-03-01

Single crystal phosphor faceplates are epitaxial phosphors grown on crystalline substrates with the advantages of high light output, resolution, and extended operational life. Single crystal phosphor faceplate industrial technology in the United States is capable of providing a faceplate appropriate to the projection industry of up to four (4) inches in diameter. Projection systems incorporating cathode ray tubes utilizing single crystal phosphor faceplates will produce 1500 lumens of white light with 1000 lines of resolution, non-interlaced. This 1500 lumen projection system will meet all of the currently specified luminance and resolution requirements of Visual Display systems for flight simulators. Significant logistic advantages accrue from the introduction of single crystal phosphor faceplate CRT's. Specifically, the full performance life of a CRT is expected to increase by a factor of five (5); ie, from 2000 to 10,000 hours of operation. There will be attendant reductions in maintenance time, spare CRT requirements, system down time, etc. The increased brightness of the projection system will allow use of lower gain, lower cost simulator screen material. Further, picture performance characteristics will be more balanced across the full simulator.

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.

Elastic properties of Ti-24Nb-4Zr-8Sn single crystals with bcc crystal structure

International Nuclear Information System (INIS)

Zhang, Y.W.; Li, S.J.; Obbard, E.G.; Wang, H.; Wang, S.C.; Hao, Y.L.; Yang, R.

2011-01-01

Research highlights: → The single crystals of Ti2448 alloy with the bcc crystal structure were prepared. → The elastic moduli and constants were measured by several resonant methods. → The crystal shows significant elastic asymmetry in tension and compression. → The crystal exhibits weak nonlinear elasticity with large elastic strain ∼2.5%. → The crystal has weak atomic interactions against crystal distortion to low symmetry. - Abstract: Single crystals of Ti2448 alloy (Ti-24Nb-4Zr-8Sn in wt.%) were grown successfully using an optical floating-zone furnace. Several kinds of resonant methods gave consistent Young's moduli of 27.1, 56.3 and 88.1 GPa and shear moduli of 34.8, 11.0 and 14.6 GPa for the , and oriented single crystals, and C 11 , C 12 and C 44 of 57.2, 36.1 and 35.9 GPa respectively. Uniaxial testing revealed asymmetrical elastic behaviors of the crystals: tension caused elastic softening with a large reversible strain of ∼4% and a stress plateau of ∼250 MPa, whereas compression resulted in gradual elastic stiffening with much smaller reversible strain. The crystals exhibited weak nonlinear elasticity with a large elastic strain of ∼2.5% and a high strength, approaching ∼20% and ∼30% of its ideal shear and ideal tensile strength respectively. The crystals showed linear elasticity with a small elastic strain of ∼1%. These elastic deformation characteristics have been interpreted in terms of weakened atomic interactions against crystal distortion to low crystal symmetry under external applied stresses. These results are consistent with the properties of polycrystalline Ti2448, including high strength, low elastic modulus, large recoverable strain and weak strengthening effect due to grain refinement.

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.

Defect free single crystal thin layer

KAUST Repository

Elafandy, Rami Tarek Mahmoud; Ooi, Boon S.

2016-01-01

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.

Effect of Crystal Orientation on Fatigue Failure of Single Crystal Nickel Base Turbine Blade Superalloys

Science.gov (United States)

Arakere, Nagaraj K.; Swanson, Gregory R.

2000-01-01

High Cycle Fatigue (HCF) induced failures in aircraft gas-turbine engines is a pervasive problem affecting a wide range of components and materials. HCF is currently the primary cause of component failures in gas turbine aircraft engines. Turbine blades in high performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys. Single-crystal Nickel-base superalloys were developed to provide superior creep, stress rupture, melt resistance and thermomechanical fatigue capabilities over polycrystalline alloys previously used in the production of turbine blades and vanes. Currently the most widely used single crystal turbine blade superalloys are PWA 1480/1493 and PWA 1484. These alloys play an important role in commercial, military and space propulsion systems. PWA1493, identical to PWA1480, but with tighter chemical constituent control, is used in the NASA SSME (Space Shuttle Main Engine) alternate turbopump, a liquid hydrogen fueled rocket engine. Objectives for this paper are motivated by the need for developing failure criteria and fatigue life evaluation procedures for high temperature single crystal components, using available fatigue data and finite element modeling of turbine blades. Using the FE (finite element) stress analysis results and the fatigue life relations developed, the effect of variation of primary and secondary crystal orientations on life is determined, at critical blade locations. The most advantageous crystal orientation for a given blade design is determined. Results presented demonstrates that control of secondary and primary crystallographic orientation has the potential to optimize blade design by increasing its resistance to fatigue crack growth without adding additional weight or cost.

Investigations on the nucleation kinetics of γ-glycine single crystal

International Nuclear Information System (INIS)

Yogambal, C.; Rajan Babu, D.; Ezhil Vizhi, R.

2014-01-01

Single crystals of γ-glycine were grown by slow evaporation technique. The crystalline system was confirmed by single crystal X-ray diffraction analysis. The optical absorption study has shown that the grown crystal possesses lower cut-off wavelength. Solubility and metastable zone width were estimated for different temperatures. The induction period of title compound was determined by varying the temperature and concentration. Nucleation parameters such as Gibbs volume free energy change (ΔG v ), interfacial tension (γ), critical free energy change of the nucleus (ΔG ⁎ ), nucleation rate (J), number of molecules in the critical nucleus (i ⁎ ) have been calculated for the aqueous solution grown γ-glycine single crystals. The second harmonic generation (SHG) of γ-glycine was confirmed by Q-switched Nd:YAG laser technique

Single crystal growth of yttrium calcium oxy borate (YCOB) crystals by flux technique and their characterization. CP-3.5

International Nuclear Information System (INIS)

Arun Kumar, R.; Senthilkumar, M.; Dhanasekaran, R.

2007-01-01

Yttrium calcium oxy borate single crystals were grown by the flux technique for the first time. Polycrystalline YCOB material was prepared by solid state reaction method. Single crystals of YCOB were grown using boron-tri-oxide flux. Several transparent single crystals of dimensions 10 x 5 x 5 mm 3 were obtained. The grown crystals were characterized by powder XRD and UV- VIS-NIR studies. The results of powder XRD confirm the crystalline structure of YCOB. The UV- VIS-NIR transmission spectrum reveals that the crystal is highly transparent (above 75%) from ultraviolet (220 nm) to near IR regions enabling it as a suitable candidate for high power UV applications

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.

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

KAUST Repository

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

2015-01-01

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

Highly efficient single-pass sum frequency generation by cascaded nonlinear crystals

DEFF Research Database (Denmark)

Hansen, Anders Kragh; Andersen, Peter E.; Jensen, Ole Bjarlin

2015-01-01

, despite differences in the phase relations of the involved fields. An unprecedented 5.5 W of continuous-wave diffraction-limited green light is generated from the single-pass sum frequency mixing of two diode lasers in two periodically poled nonlinear crystals (conversion efficiency 50%). The technique......The cascading of nonlinear crystals has been established as a simple method to greatly increase the conversion efficiency of single-pass second-harmonic generation compared to a single-crystal scheme. Here, we show for the first time that the technique can be extended to sum frequency generation...... is generally applicable and can be applied to any combination of fundamental wavelengths and nonlinear crystals....

Synthesis, crystal structure, and magnetic properties of two-dimensional divalent metal glutarate/dipyridylamine coordination polymers, with a single crystal-to-single crystal transformation in the copper derivative

International Nuclear Information System (INIS)

Montney, Matthew R.; Supkowski, Ronald M.; Staples, Richard J.; LaDuca, Robert L.

2009-01-01

Hydrothermal reaction of divalent metal chlorides with glutaric acid and 4,4'-dipyridylamine (dpa) has afforded an isostructural family of coordination polymers with formulation [M(glu)(dpa)] n (M=Co (1), Ni (2), Cu (3); glu=glutarate). Square pyramidal coordination is seen in 1-3, with semi-ligation of a sixth donor to produce a '5+1' extended coordination sphere. Neighboring metal atoms are linked into 1D [M(glu)] n neutral chains through chelating/monodentate bridging glutarate moieties with a syn-anti binding mode, and semi-chelation of the pendant carboxylate oxygen. These chains further connect into 2D layers through dipodal dpa ligands. Neighboring layers stack into the pseudo 3D crystal structure of 1-3 through supramolecular hydrogen bonding between dpa amine units and the semi-chelated glutarate oxygen atoms. The variable temperature magnetic behavior of 1-3 was explored and modeled as infinite 1D Heisenberg chains. Notably, complex 3 undergoes a thermally induced single crystal-to-single crystal transformation between centric and acentric space groups, with a conformationally disordered unilayer structure at 293 K and an ordered bilayer structure at 173 K. All materials were further characterized via infrared spectroscopy and elemental and thermogravimetric analyses. - Graphical abstract: The coordination polymers [M(glu)(dpa)] n (M=Co (1), Ni (2), Cu (3); glu=glutarate, dpa=4,4'-dipyridylamine) exhibit 2D layer structures based on 1D [M(glu)] n chains linked through dpa tethers. Antiferromagnetic coupling is observed for 2 and 3, while ferromagnetism is predominant in 1. Compound 3 undergoes a thermally induced single crystal-to-single crystal transformation from an acentric to a centrosymmetric space group

Irradiation creep in zirconium single crystals

International Nuclear Information System (INIS)

MacEwen, S.R.; Fidleris, V.

1976-07-01

Two identical single crystals of crystal bar zirconium have been creep tested in reactor. Both specimens were preirradiated at low stress to a dose of about 4 x 10 23 n/m 2 (E > 1 MeV), and were then loaded to 25 MPa. The first specimen was loaded with reactor at full power, the second during a shutdown. The loading strain for both crystals was more than an order of magnitude smaller than that observed when an identical unirradiated crystal was loaded to the same stress. Both crystals exhibited periods of primary creep, after which their creep rates reached nearly constant values when the reactor was at power. During shutdowns the creep rates decreased rapidly with time. Electron microscopy revealed that the irradiation damage consisted of prismatic dislocation loops, approximately 13.5 nm in diameter. Cleared channels, identified as lying on (1010) planes, were also observed. The results are discussed in terms of the current theories for flux enhanced creep in the light of the microstructures observed. (author)

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

Growth and characterization of nonlinear optical single crystals: bis ...

Indian Academy of Sciences (India)

Administrator

molecules have received great attention for NLO applica- tions. However ... Figure 3. Single crystals of bis(cyclohexylammonium) terephthalate (crystal a) and cyclohexylammo- .... from ground state to higher energy states.17 Optical window ...

Electrolytic coloration and spectral properties of hydroxyl-doped potassium chloride single crystals

International Nuclear Information System (INIS)

Gu Hongen; Wu Yanru

2011-01-01

Hydroxyl-doped potassium chloride single crystals are colored electrolytically at various temperatures and voltages using a pointed cathode and a flat anode. Characteristic OH - spectral band is observed in the absorption spectrum of uncolored single crystal. Characteristic O - , OH - , U, V 2 , V 3 , O 2- -V a + , F, R 2 and M spectral bands are observed simultaneously in absorption spectra of colored single crystals. Current-time curve for electrolytic coloration of hydroxyl-doped potassium chloride single crystal and its relationship with electrolytic coloration process are given. Production and conversion of color centers are explained. - Highlights: → Expanded the traditional electrolysis method. → Hydroxyl-doped potassium chloride crystals were colored electrolytically for the first time. → Useful V, F and F-aggregate color centers were produced in colored crystals. → V color centers were produced directly and F and F-aggregate color centers indirectly.

X-ray dosimetry of TlGaSe2 single crystals

International Nuclear Information System (INIS)

Kerimova, E.M.; Mustafaeva, S.N.; Mamedbeili, S.D.; Jabarov, J.N.; Iskenderova, P.M.; Kazimov, S.B.

2002-01-01

TlGaSe 2 compound belongs to group of layered semiconductors of A 3 B 3 C 2 6 -type. Photoelectric and optical properties of TlGaSe 2 single crystals were investigated in detail. Influence of gamma-, electron and neutron radiation on photoelectric properties of TlGaSe 2 single crystals is investigated too. The present work deals with experimental results relative to X-ray dosimetric characteristics of TlGaSe 2 crystals at 300 K. X-ray conductivity and X-ray dosimetric characteristic measurements are carried out in low load resistance regime. The source of X-ray radiation is the installation of X-ray diffraction analysis (URS-55a) with the BCV-2(Cu). Intensity of X-ray radiation (E) is regulated by measurement with current variation in tube at each given value of X-ray radiation dose E (R/min) are measured by crystal dosimeter DRGZ-02. X-ray conductivity coefficients K σ characterising X-ray sensitivity of investigated crystals are determined as the relative change of conductivity under X-ray radiation a per dose. There have been determined values of characteristic coefficients of TlGaSe 2 single crystal X-ray conductivity at different values of accelerating voltage (V a ) on the tube and corresponding doses of X-ray radiation. Analysis of obtained data showed that X-ray conductivity coefficients K σ in studied crystals are regularly decreased (from 0.276 to 0.033) as with the rise of dose (E=0.75-78.0 R/min) as with the increase of values of V a on X-ray tube (V a =254-50 keV). One of the possible reasons of observed regularities is that X-ray conductivity in investigated crystals, especially at comparatively low V a is due predominantly to radiation of thin layer of crystal. In this case with the rise of radiation intensity there have been started to prevail the mechanism of surface quadratic recombination which leads to observed decrease of X-ray conductivity. With the rise of accelerating potential 'effective hardness' is increased, as a result of which there

Laser generation in opal-like single-crystal and heterostructure photonic crystals

Science.gov (United States)

Kuchyanov, A. S.; Plekhanov, A. I.

2016-11-01

This study describes the laser generation of a 6Zh rhodamine in artificial opals representing single-crystal and heterostructure films. The spectral and angular properties of emission and the threshold characteristics of generation are investigated. In the case where the 6Zh rhodamine was in a bulk opal, the so-called random laser generation was observed. In contrast to this, the laser generation caused by a distributed feedback inside the structure of the photonic bandgap was observed in photonic-crystal opal films.

Laser induced single-crystal transition in polycrystalline silicon

International Nuclear Information System (INIS)

Vitali, G.; Bertolotti, M.; Foti, G.; Rimini, E.

1978-01-01

Transition to single crystal of polycrystalline Si material underlying a Si crystal substrate of 100 orientation was obtained via laser irradiation. The changes in the structure were analyzed by reflection high energy electron diffraction and by channeling effect technique using 2.0 MeV He Rutherford scattering. The power density required to induce the transition in a 4500 A thick polycrystalline layer is about 70 MW/cm 2 (50ns). The corresponding amorphous to single transition has a threshold of about 45 MW/cm 2 . (orig.) 891 HPOE [de

Cyclic saturation dislocation structures of multiple-slip-oriented copper single crystals

International Nuclear Information System (INIS)

Li, X.W.; Chinese Academy of Sciences, Shenyang; Umakoshi, Y.; Li, S.X.; Wang, Z.G.

2001-01-01

The dislocation structures of [011] and [ anti 111] multiple-slip-oriented Cu single crystals cyclically saturated at constant plastic strain amplitudes were investigated through transmission electron microscopy. The results obtained on [001] multiple-slip-oriented Cu single crystals were also included for summarization. Unlike the case for single-slip-oriented Cu single crystals, the crystallographic orientation has a strong effect on the saturation dislocation structure in these three multiple-slip-oriented crystals. For the [011] crystal, different dislocation patterns such as veins, PSB walls, labyrinths and PSB ladders were observed. The formation of PSB ladders is believed to be a major reason for the existence of a plateau region in the cyclic stress-strain (CSS) curve for the [011] crystal. The cyclic saturation dislocation structure of a [ anti 111] crystal cycled at a low applied strain amplitude γ pl of 2.0 x 10 -4 was found to consist of irregular cells, which would develop into a more regular arrangement (e. g. PSB ladder-like) and the scale of which tends to decrease with increasing γ pl . Finally, three kinds of representative micro-deformation mode were summarized and termed as labyrinth-mode (or [001]-mode), cell-mode (or [ anti 111]-mode) and PSB ladder-mode (or [011]-mode). (orig.)

Sample Size Induced Brittle-to-Ductile Transition of Single-Crystal Aluminum Nitride

Science.gov (United States)

2015-08-01

ARL-RP-0528 ● AUG 2015 US Army Research Laboratory Sample Size Induced Brittle-to- Ductile Transition of Single-Crystal Aluminum...originator. ARL-RP-0528 ● AUG 2015 US Army Research Laboratory Sample Size Induced Brittle-to- Ductile Transition of Single-Crystal...Sample Size Induced Brittle-to- Ductile Transition of Single-Crystal Aluminum Nitride 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

Oriented growing and anisotropy of emission properties of lanthanum hexaboride single crystals

International Nuclear Information System (INIS)

Lazorenko, V.I.; Lotsko, D.V.; Platonov, V.F.; Kovalev, A.V.; Galasun, A.P.; Matvienko, A.A.; Klinkov, A.E.

1987-01-01

Single crystals of lanthanum hexaboride with preset crystallographic orientation are grown by the method of crucible-free zone melting. It is shown that oriented growing of single crystals of the given compound is possible only when using seed crystals of the required orientation because no predominant orientation of the LaB 6 growth is found in case of spontaneous crystallization. Orientation of spontaneously growing LaB 6 crystals does not depend on their growth rate, degree of the melt diffusion annealing, purity of the inital powder. Anisotropy of the electronic work function for single crystal lanthanum hexaboride is confirmed. Its value grows as (100)<(110)<(111). Conditions of the preliminary thermovacuum purification of the surface are shown to affect the measured work function

Neutron Transmission of Single-crystal Sapphire Filters

Science.gov (United States)

Adib, M.; Kilany, M.; Habib, N.; Fathallah, M.

2005-05-01

An additive formula is given that permits the calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-sections as a function of sapphire temperature and crystal parameters. We have developed a computer program that allows calculations of the thermal neutron transmission for the sapphire rhombohedral structure and its equivalent trigonal structure. The calculated total cross-section values and effective attenuation coefficient for single-crystalline sapphire at different temperatures are compared with measured values. Overall agreement is indicated between the formula and experimental data. We discuss the use of sapphire single crystal as a thermal neutron filter in terms of the optimum cystal thickness, mosaic spread, temperature, cutting plane and tuning for efficient transmission of thermal-reactor neutrons.

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.

Single Crystal Filters for Neutron Spectrometry

International Nuclear Information System (INIS)

Habib, N.

2008-01-01

A study of neutron transmission properties trough a large single crystals specimens of Si, Ge, Pb, Bi and sapphire at 300 K and 80 K have been made for a wide range of neutron energies. The effectiveness of such filters is given by the ratio of the total cross-section of unwanted epithermal neutrons to that the desired thermal neutron beam and by the optimum choice of the crystal orientation, its mosaic spread, thickness and temperature.Our study indicates that sapphire is significantly more effective than the others for a wide range of neutron energies

A Comparative Study of Chemically and Biologically Synthesized MgO Nanomaterial for Liquefied Petroleum Gas Detection

Science.gov (United States)

Thirupathi, Rampelly; Solleti, Goutham; Sreekanth, Tirumala; Sadasivuni, Kishor Kumar; Venkateswara Rao, Kalagadda

2018-03-01

The exceptional chemical and physical properties of nanostructured materials are extremely suitable for designing new and enhanced sensing devices, particularly gas sensors and biosensors. The present work describes the synthesis of magnesium oxide (MgO) nanoparticles through two methods: a green synthesis using aloe vera plant extract and a chemical method using a glycine-based solution combustion route. In a single step, the extracted organic molecules from aloe vera plants were used to reduce metal ions by the green method. MgO nanoparticles were coated onto the interdigital electrode using the drop-drying method. The dynamic gas-sensing characteristics were measured for liquefied petroleum gas (LPG) at different concentrations and various temperatures. The MgO nanoparticles were characterized by using x-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy to determine the size and structure of the particles. The product's functional properties were analyzed by Fourier transform-infrared spectroscopy and UV-visible spectroscopy. We found that the LPG sensing behavior of biologically synthesized MgO registers excellent sensitivity at various operating temperatures.

Iron single crystal growth from a lithium-rich melt

Science.gov (United States)

Fix, M.; Schumann, H.; Jantz, S. G.; Breitner, F. A.; Leineweber, A.; Jesche, A.

2018-03-01

α -Fe single crystals of rhombic dodecahedral habit were grown from a Li84N12Fe∼3 melt. Crystals of several millimeter along a side form at temperatures around T ≈ 800 ° C. Upon further cooling the growth competes with the formation of Fe-doped Li3N. The b.c.c. structure and good sample quality of α -Fe single crystals were confirmed by X-ray and electron diffraction as well as magnetization measurements and chemical analysis. A nitrogen concentration of 90 ppm was detected by means of carrier gas hot extraction. Scanning electron microscopy did not reveal any sign of iron nitride precipitates.

Strengthening mechanisms of Fe nanoparticles for single crystal Cu–Fe alloy

International Nuclear Information System (INIS)

Shi, Guodong; Chen, Xiaohua; Jiang, Han; Wang, Zidong; Tang, Hao; Fan, Yongquan

2015-01-01

A single crystal Cu–Fe alloy with finely dispersed precipitate Fe nanoparticles was fabricated in this study. The interface relationship of iron nanoparticle and copper matrix was analyzed with a high-resolution transmission electron microscope (HRTEM), and the effect of Fe nanoparticles on mechanical properties of single crystal Cu–Fe alloy was discussed. Results show that, the finely dispersed Fe nanoparticles can be obtained under the directional solidification condition, with the size of 5–50 nm and the coherent interface between the iron nanoparticle and the copper matrix. Single crystal Cu–Fe alloy possesses improved tensile strength of 194.64 MPa, and total elongation of 44.72%, respectively, at room temperature, in contrast to pure Cu sample. Nanoparticles which have coherent interface with matrix can improve the dislocation motion state. Some dislocations can slip through the nanoparticle along the coherent interface and some dislocations can enter into the nanoparticles. Thus to improve the tensile strength of single crystal Cu–Fe alloy without sacrificing the ductility simultaneously. Based on the above analyses, strengthening mechanisms of Fe nanoparticles for single crystal Cu–Fe alloy was described

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.

Electrolytic coloration and spectral properties of hydroxyl-doped potassium bromide single crystals

International Nuclear Information System (INIS)

Qi, Lan; Song, Cuiying; Gu, Hongen

2013-01-01

Hydroxyl-doped potassium bromide single crystals are colored electrolytically at various temperatures and voltages by using a pointed cathode and a flat anode. The characteristic OH − spectral band is observed in absorption spectrum of uncolored single crystal. The characteristic O − , OH − , U, V 2 , O 2− −V a + , M L1 , F and M spectral bands are observed simultaneously in absorption spectra of colored single crystals. Current–time curve for electrolytic coloration of hydroxyl-doped potassium bromide single crystal and its relationship with electrolytic coloration processes are given. Production and conversion of color centers are explained. - Highlights: ► We expanded the traditional electrolysis method. ► Hydroxyl-doped potassium bromide crystals were colored electrolytically for the first time. ► Useful V, F and F-aggregate color centers were produced in colored crystals. ► V color centers were produced directly and F as well as F-aggregate color centers indirectly.

Crystal growth and optical properties of Sm:CaNb2O6 single crystal

International Nuclear Information System (INIS)

Di Juqing; Xu Xiaodong; Xia Changtai; Zeng Huidan; Cheng Yan; Li Dongzhen; Zhou Dahua; Wu Feng; Cheng Jimeng; Xu Jun

2012-01-01

Highlights: ► Sm:CaNb 2 O 6 single crystal was grown by the Czochralski method. ► Thermal expansion coefficients and J–O parameters were calculated. ► We found that this crystal had high quantum efficiency of 97%. - Abstract: Sm:CaNb 2 O 6 single crystal has been grown by the Czochralski method. Its high-temperature X-ray powder diffraction, optical absorption, emission spectroscopic as well as lifetime have been studied. Thermal expansion coefficients (α), J–O parameters (Ω i ), radiative lifetime (τ rad ), branching ratios (β) and stimulated emission cross-sections (σ e ) were calculated. The quantum efficiency (η) was calculated to be 97%. The intense peak emission cross section at 610, 658 nm were calculated to be 2.40 × 10 −21 , 2.42 × 10 −21 cm 2 . These results indicate that Sm:CaNb 2 O 6 crystal has potential use in visible laser and photonic devices area.

Polyethylene Nanocomposites for the Next Generation of Ultralow-Transmission-Loss HVDC Cables: Insulation Containing Moisture-Resistant MgO Nanoparticles.

Science.gov (United States)

Pourrahimi, Amir Masoud; Pallon, Love K H; Liu, Dongming; Hoang, Tuan Anh; Gubanski, Stanislaw; Hedenqvist, Mikael S; Olsson, Richard T; Gedde, Ulf W

2016-06-15

The use of MgO nanoparticles in polyethylene for cable insulation has attracted considerable interest, although in humid media the surface regions of the nanoparticles undergo a conversion to a hydroxide phase. A facile method to obtain MgO nanoparticles with a large surface area and remarkable inertness to humidity is presented. The method involves (a) low temperature (400 °C) thermal decomposition of Mg(OH)2, (b) a silicone oxide coating to conceal the nanoparticles and prevent interparticle sintering upon exposure to high temperatures, and (c) heat treatment at 1000 °C. The formation of the hydroxide phase on these silicone oxide-coated MgO nanoparticles after extended exposure to humid air was assessed by thermogravimetry, infrared spectroscopy, and X-ray diffraction. The nanoparticles showed essentially no sign of any hydroxide phase compared to particles prepared by the conventional single-step thermal decomposition of Mg(OH)2. The moisture-resistant MgO nanoparticles showed improved dispersion and interfacial adhesion in the LDPE matrix with smaller nanosized particle clusters compared with conventionally prepared MgO. The addition of 1 wt % moisture-resistant MgO nanoparticles was sufficient to decrease the conductivity of polyethylene 30 times. The reduction in conductivity is discussed in terms of defect concentration on the surface of the moisture-resistant MgO nanoparticles at the polymer/nanoparticle interface.

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

Study of structural and optical properties of YAG and Nd:YAG single crystals

Energy Technology Data Exchange (ETDEWEB)

Kostić, S. [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, Zemun, Belgrade (Serbia); Lazarević, Z.Ž., E-mail: lzorica@yahoo.com [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, Zemun, Belgrade (Serbia); Radojević, V. [Faculty of Technology and Metallurgy, University of Belgrade, Belgrade (Serbia); Milutinović, A.; Romčević, M.; Romčević, N.Ž. [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, Zemun, Belgrade (Serbia); Valčić, A. [Faculty of Technology and Metallurgy, University of Belgrade, Belgrade (Serbia)

2015-03-15

Highlights: • Transparent YAG and pale pink Nd:YAG single crystals were produced by the Czochralski technique. • Growth mechanisms and shape of the liquid/solid interface and incorporation of Nd{sup 3+} were studied. • The structure of the crystals was investigated by X-ray diffraction, Raman and IR spectroscopy. • The 15 Raman and 17 IR modes were observed. • The obtained YAG and Nd:YAG single crystals were without core and of good optical quality. - Abstract: Yttrium aluminum garnet (YAG, Y{sub 3}Al{sub 5}O{sub 12}) and yttrium aluminum garnet doped with neodymium (Nd:YAG) single crystals were grown by the Czochralski technique. The critical diameter and the critical rate of rotation were calculated. Suitable polishing and etching solutions were determined. As a result of our experiments, the transparent YAG and pale pink Nd:YAG single crystals were produced. The obtained crystals were studied by X-ray diffraction, Raman and IR spectroscopy. The crystal structure was confirmed by XRD. The 15 Raman and 17 IR modes were observed. The Raman and IR spectroscopy results are in accordance with X-ray diffraction analysis. The obtained YAG and Nd:YAG single crystals were without core and of good optical quality. The absence of a core was confirmed by viewing polished crystal slices. Also, it is important to emphasize that the obtained Nd:YAG single crystal has a concentration of 0.8 wt.% Nd{sup 3+} that is characteristic for laser materials.

Reversible Single-Crystal-to-Single-Crystal Structural Transformation in a Mixed-Ligand 2D Layered Metal-Organic Framework: Structural Characterization and Sorption Study

Directory of Open Access Journals (Sweden)

Chih-Chieh Wang

2017-12-01

Full Text Available A 3D supramolecular network, [Cd(bipy(C4O4(H2O2]·3H2O (1 (bipy = 4,4′-bipyridine and C4O42− = dianion of H2C4O4, constructed by mixed-ligand two-dimensional (2D metal-organic frameworks (MOFs has been reported and structurally determined by the single-crystal X-ray diffraction method and characterized by other physicochemical methods. In 1, the C4O42− and bipy both act as bridging ligands connecting the Cd(II ions to form a 2D layered MOF, which are then extended to a 3D supramolecular network via the mutually parallel and interpenetrating arrangements among the 2D-layered MOFs. Compound 1 shows a two-step dehydration process with weight losses of 11.0% and 7.3%, corresponding to the weight-loss of three guest and two coordinated water molecules, respectively, and exhibits an interesting reversible single-crystal-to-single-crystal (SCSC structural transformation upon de-hydration and re-hydration for guest water molecules. The SCSC structural transformation have been demonstrated and monitored by single-crystal and X-ray powder diffraction, and thermogravimetic analysis studies.

Co2FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

International Nuclear Information System (INIS)

Belmeguenai, M.; Tuzcuoglu, H.; Zighem, F.; Chérif, S. M.; Moch, P.; Gabor, M. S.; Petrisor, T.; Tiusan, C.

2014-01-01

10 nm and 50 nm Co 2 FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (T a ), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing T a , while the uniaxial anisotropy field is nearly unaffected by T a within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with T a . Finally, the FMR linewidth decreases when increasing T a , due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10 −3 and 1.3×10 −3 for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively)

Morphological and optical studies of zinc oxide doped MgO

Energy Technology Data Exchange (ETDEWEB)

Othman, Zayani Jaafar, E-mail: jaafar.zayani@yahoo.fr; Matoussi, Adel

2016-06-25

This paper reports morphological and optical characterizations of sintered (ZnO){sub 1−x}(MgO){sub x} composite materials. The effects of MgO doping content on these pellets properties have been analyzed. The SEM observations have shown rougher surfaces of the samples covered by grains having prismatic shapes and different sizes. From reflectance and absorption measurements, we have determined the band gap energy which tends to augment from 3.287 to 3.827 eV as the doping content increases. This widening of the optical band gap is explained by the Burstein-Moss effect which causes a significant increase of electron concentration (2.89 10{sup 18}−5.1910{sup 20} cm{sup −3}). In addition, the absorption coefficient, Urbach energy, optical constants (refractive index, extinction coefficient, dielectric constant) and dispersion parameters, such as E{sub 0} (single-oscillator energy), E{sub d} (dispersive energy) were determined of the (ZnO){sub 1−x}(MgO){sub x} composites and analyzed. - Highlights: • (ZnO){sub 1−x}(MgO){sub x} composites were synthesized by solid state sintering method. • MgO doping increased the band gap energy. • SEM observations have shown a decrease of grain sizes when the MgO doping increases. • Optical constants and dispersion parameters were determined and analyzed.

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.

Regularities of recrystallization in rolled Zr single crystals

International Nuclear Information System (INIS)

Isaenkova, M; Perlovich, Yu; Fesenko, V; Krymskaya, O; Krapivka, N; Thu, S S

2015-01-01

Experiments by rolled single crystals give a more visible conception of the operating mechanisms of plastic deformation and the following recrystallization, than experiments by polycrystals. Studies by usage of X-ray diffraction methods were conducted by Zr single crystals. It was revealed, that regions of the α-Zr matrix, deformed mainly by twinning, are characterized with decreased tendency to recrystallization. Orientations of recrystallized α-Zr grains correspond to “slopes” of maxima in the rolling texture, where the level of crystalline lattice distortion is maximal and the number of recrystallization nuclei is most of all. (paper)

The use of single-crystal iron frames in transient field measurements

International Nuclear Information System (INIS)

Zalm, P.C.; Laan, J. van der; Middelkoop, G. van

1979-01-01

Single-crystal Fe frames have been investigated for use as a ferromagnetic backing in transient magnetic field experiments. For this purpose the surface magnetization as a function of applied magnetic field has been determined with the magneto-optical Kerr effect. The frames, which have two sides parallel to the crystal axis, can be fully magnetized at low external fields such that fringing fields are negligibly small. These single-crystal Fe backings have been used in several transient magnetic field experiments. Comparison of the measured precession angles with previous results, obtained in polycrystalline Fe foils at high external magnetic fields, shows that the single-crystal backings are satisfactory. After extended periods of heavy-ion bombardment the crystals exhibited no radiation damage effects. The absence of fringing fields leads to a reduction of a factor of four in the measuring time for transient field experiments. (Auth.)

Growth features of ammonium hydrogen d-tartrate single crystals

Indian Academy of Sciences (India)

Unknown

Abstract. Ammonium hydrogen d-tartrate (d-AHT) single crystals were grown in silica gel. The growth fea- ... solution (specific gravity, 1⋅04 g/cc) with d-tartaric acid solution having ... resulting in the production of crystal nuclei. The interface.

Effect of MgO on compositions of the system CaO-Al2O3-Fe2O3. Solubility

Directory of Open Access Journals (Sweden)

Palomo, Ángel

1986-12-01

Full Text Available Five different compositions belonging to the equilibrium system CaO-Al2O3-Fe2O3 were dopep with a fixed quantity of MgO (6,5% wt. The compositions, which lie in different primary fields of crystallization and in different triangles of compatibility, were submitted to several thermal treatments. Each composition, which had previously been melted, originates in its solidification the aluminates and ferrites which are usual in the interstitial phase of clinker Portland, although they are in different microstructural arrangements. The effect of MgO on the generated microstructures has been shown. Also, the solubility of MgO on the aluminic and ferritic phases has been measured.CCinco composiciones diferentes pertenecientes al sistema de equilibrio CaO-Al2O3-Fe2O3 fueron dopadas con una cantidad fija de MgO (6,5%. Las cinco composiciones, que están situadas sobre diferentes campos primarios de cristalización y/o sobre diferentes triángulos de compatibilidad, fueron sometidas a varios tratamientos térmicos. Cada composición (previamente fundida origina en su solidificación los aluminatos y ferritos habituales en la fase intersticial del clinker portland, aunque ordenados en microestructuras diferentes. Se ha comprobado el efecto del MgO sobre las microestructuras generadas, así como su solubilidad en las fases alumínicas y ferríticas.

The crystal structure and twinning of neodymium gallium perovskite single crystals

International Nuclear Information System (INIS)

Ubizskii, S.B.; Vasylechko, L.O.; Savytskii, D.I.; Matkovskii, A.O.; Syvorotka, I.M.

1994-01-01

By means of X-ray structure analysis, the crystal structure of neodymium gallium perovskite (NGP) single crystals (NdGaO 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 2 Cu 3 O 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 3 and LaAlO 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)

Types of defect ordering in undoped and lanthanum-doped Bi2201 single crystals

International Nuclear Information System (INIS)

Martovitsky, V. P.

2006-01-01

Undoped and lanthanum-doped Bi2201 single crystals having a perfect average structure have been comparatively studied by x-ray diffraction. The undoped Bi2201 single crystals exhibit very narrow satellite reflections; their half-width is five to six times smaller than that of Bi2212 single crystals grown by the same technique. This narrowness indicates three-dimensional defect ordering in the former crystals. The lanthanumdoped Bi2201 single crystals with x = 0.7 and T c = 8-10 K exhibit very broad satellite reflections consisting of two systems (modulations) misoriented with respect to each other. The modulation-vector components of these two modulations are found to be q 1 = 0.237b* + 0.277c* and q 2 = 0.238b* + 0.037c*. The single crystals having a perfect average structure and a homogeneous average distribution of doping lanthanum consist of 70-to 80-A-thick layers that alternate along the c axis and have two different types of modulated superlattice. The crystals having a less perfect average structure also consist of alternating layers, but they have different lanthanum concentrations. The low value of T c in the undoped Bi2201 single crystals (9.5 K) correlates with three-dimensional defect ordering in them, and an increase in T c to 33 K upon lanthanum doping can be related to a thin-layer structure of these crystals and to partial substitution of lanthanum for the bismuth positions

WIPP Magnesium Oxide (MgO) - Planned Change Request

Science.gov (United States)

On April 10, 2006, the DOE submitted a planned change request pertaining to the amount of MgO emplaced in the WIPP repository. MgO is an engineered barrier that DOE included as part of the original WIPP Certification Decision.

Disappearing Enantiomorphs: Single Handedness in Racemate Crystals.

Science.gov (United States)

Parschau, Manfred; Ernst, Karl-Heinz

2015-11-23

Although crystallization is the most important method for the separation of enantiomers of chiral molecules in the chemical industry, the chiral recognition involved in this process is poorly understood at the molecular level. We report on the initial steps in the formation of layered racemate crystals from a racemic mixture, as observed by STM at submolecular resolution. Grown on a copper single-crystal surface, the chiral hydrocarbon heptahelicene formed chiral racemic lattice structures within the first layer. In the second layer, enantiomerically pure domains were observed, underneath which the first layer contained exclusively the other enantiomer. Hence, the system changed from a 2D racemate into a 3D racemate with enantiomerically pure layers after exceeding monolayer-saturation coverage. A chiral bias in form of a small enantiomeric excess suppressed the crystallization of one double-layer enantiomorph so that the pure minor enantiomer crystallized only in the second layer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrogen absorption in thin ZnO films prepared by pulsed laser deposition

OpenAIRE

Meilkhova, O.; Čížek, J.; Lukáč,, F.; Vlček, M.; Novotný, M.; Bulíř, J.; Lančok, J.; Anwand, W.; Brauer, G.; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.

2013-01-01

ZnO films with thickness of ~80 nm were grown by pulsed laser deposition (PLD) on MgO (1 0 0) single crystal and amorphous fused silica (FS) substrates. Structural studies of ZnO films and a high quality reference ZnO single crystal were performed by slow positron implantation spectroscopy (SPIS). It was found that ZnO films exhibit significantly higher density of defects than the reference ZnO crystal. Moreover, the ZnO film deposited on MgO substrate exhibits higher concentration of defects...

Twinning processes in Cu-Al-Ni martensite single crystals investigated by neutron single crystal diffraction method

Czech Academy of Sciences Publication Activity Database

Molnar, P.; Šittner, P.; Novák, V.; Lukáš, Petr

2008-01-01

Roč. 481, Sp.Iss.SI (2008), s. 513-517 ISSN 0921-5093 R&D Projects: GA AV ČR IAA100480704 Institutional research plan: CEZ:AV0Z10480505 Keywords : Cu-Al-Ni * single crystals * neutron diffraction Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.806, year: 2008

Electronic transport properties of single crystal thallium-2201 superconductors

International Nuclear Information System (INIS)

Yandrofski, R.M.

1992-01-01

Four-probe resistance measurements on single crystals of the calcium-free thallium-based superconducting Tl 2 Ba 2 CuO 6+σ phase (Tl-2201) were performed in magnetic fields up to 12 Telsa. Single crystals of sizes were grown by a self-flux technique and were characterized by single crystal X-ray diffraction and X-ray Dispersive Analysis. Field measurements were taken at dc and at low frequencies using a lock-in technique. Techniques were developed to oxygen-anneal the as-grown single crystals to generate single crystal samples of the same Tl-2201 phase with varying transition interaction effect against appropriate composite general alternatives are developed for the standard two-way layout with a single observation per cell. Nonparametric aligned-rank test procedures are introduced. One of the new procedures is shown to be equivalent to a slight modification of the previously studied Latin square procedures when the factors have the same number of levels. The equal in distribution technique is used to show that any statistic based on the joint ranks should not be used to test the hypotheses of interest. The tests based on aligning with the averages do not depend on the nuisance main effects, while those based on aligning with the median do depend on the nuisance main effects. The relative power performance of the competing tests are examined via Monte Carlo simulation. Power studies conducted on the 5 x 5, 5 x 6, and 5 x 9 two-way layouts with one observation per cell show that the new procedures based on a comparison of all possible pairs of rank-profiles perform quite well for two types of product interaction, a general class of interaction effects proposed by Martin, and several sets of specific interaction effects. Approximate critical values for some of the proposed procedures are explored in the special case when the main effect parameters for one factor are known

BiI{sub 3} single crystal for room-temperature gamma ray detectors

Energy Technology Data Exchange (ETDEWEB)

Saito, T., E-mail: saito.tatsuya125@canon.co.jp [Frontier Research Center, Canon Inc., 3-30-2, Shimomaruko, Ohta-ku, Tokyo 146-8501 (Japan); Iwasaki, T. [Frontier Research Center, Canon Inc., 3-30-2, Shimomaruko, Ohta-ku, Tokyo 146-8501 (Japan); Kurosawa, S.; Yoshikawa, A. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Den, T. [Frontier Research Center, Canon Inc., 3-30-2, Shimomaruko, Ohta-ku, Tokyo 146-8501 (Japan)

2016-01-11

BiI{sub 3} single crystals were grown by the physical vapor transport method. The repeated sublimation of the starting material reduced impurities in the BiI{sub 3} single crystal to sub-ppm levels. The detector was fabricated by depositing Au electrodes on both surfaces of the 100-μm-thick BiI{sub 3} single crystal platelet. The resistivity of the BiI{sub 3} single crystal was increased by post-annealing in an iodine atmosphere (ρ=1.6×10{sup 11} Ω cm). Pulse height spectroscopy measurements showed clear peaks in the energy spectrum of alpha particles or gamma rays. It was estimated that the mobility-lifetime product was μ{sub e}τ{sub e}=3.4–8.5×10{sup −6} cm{sup 2}/V and the electron–hole pair creation energy was 5.8 eV. Our results show that BiI{sub 3} single crystals are promising candidates for detectors used in radiographic imaging or gamma ray spectroscopy.

Bloch walls in a nickel single crystal

International Nuclear Information System (INIS)

Peters, J.; Treimer, W.

2001-01-01

We present a consistent theory for the dependence of the magnetic structure in bulk samples on external static magnetic fields and corresponding experimental results. We applied the theory of micromagnetism to this crystal and calculated the Bloch wall thickness as a function of external magnetic fields. The theoretical results agree well with the experimental data, so that the Bloch wall thickness of a 71 deg. nickel single crystal was definitely determined with some hundred of nanometer

Thermopower, electrical and Hall conductivity of undoped and doped iron disilicide single crystals

Energy Technology Data Exchange (ETDEWEB)

Heinrich, A; Behr, G; Griessmann, H; Teichert, S; Lange, H

1997-07-01

The electrical transport properties of {beta}-FeSi{sub 2} single crystals have been investigated in dependence on the purity of the source material and on doping with 3d transition metals. The transport properties included are electrical conductivity, Hall conductivity and thermopower mainly in the temperature range from 4K to 300K. The single crystals have been prepared by chemical transport reaction in a closed system with iodine as transport agent. In undoped single crystals prepared with 5N Fe both electrical conductivity and thermopower depend on the composition within the homogeneity range of {beta}-FeSi{sub 2} which is explained by different intrinsic defects at the Si-rich and Fe-rich phase boundaries. In both undoped and doped single crystals impurity band conduction is observed at low temperatures but above 100K extrinsic behavior determined by shallow impurity states. The thermopower shows between 100K and 200K a significant phonon drag contribution which depends on intrinsic defects and additional doping. The Hall resistivity is considered mainly with respect to an anomalous contribution found in p-type and n-type single crystals and thin films. In addition doped single crystals show at temperatures below about 130K an hysteresis of the Hall voltage. These results make former mobility data uncertain. Comparison will be made between the transport properties of single crystals and polycrystalline material.

Growth and characterization of isotopically enriched 70Ge and 74Ge single crystals

International Nuclear Information System (INIS)

Itoh, K.

1992-10-01

Isotopically enriched 70 Ge and 74 Ge single crystals were successfully gown by a newly developed vertical Bridgman method. The system allows us to reliably grow high purity Ge single crystals of approximately 1 cm 3 volume. To our knowledge, we have grown the first 70 Ge single crystal. The electrically active chemical impurity concentration for both crystals was found to be ∼2 x cm -3 which is two order of magnitude better that of 74 Ge crystals previously grown by two different groups. Isotopic enrichment of the 70 Ge and the 74 Ge crystals is 96.3% and 96.8%, respectively. The residual chemical impurities present in both crystals were identified as phosphorus, copper, aluminum, and indium. A wide variety of experiments which take advantage of the isotopic purity of our crystals are discussed

Self-cavity lasing in optically pumped single crystals of p-sexiphenyl

International Nuclear Information System (INIS)

Yanagi, Hisao; Tamura, Kenji; Sasaki, Fumio

2016-01-01

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.

Ferromagnetism in CVT grown tungsten diselenide single crystals with nickel doping

Science.gov (United States)

Habib, Muhammad; Muhammad, Zahir; Khan, Rashid; Wu, Chuanqiang; Rehman, Zia ur; Zhou, Yu; Liu, Hengjie; Song, Li

2018-03-01

Two dimensional (2D) single crystal layered transition materials have had extensive consideration owing to their interesting magnetic properties, originating from their lattices and strong spin-orbit coupling, which make them of vital importance for spintronic applications. Herein, we present synthesis of a highly crystalline tungsten diselenide layered single crystal grown by chemical vapor transport technique and doped with nickel (Ni) to tailor its magnetic properties. The pristine WSe2 single crystal and Ni-doped crystal were characterized and analyzed for magnetic properties using both experimental and computational aspects. It was found that the magnetic behavior of the 2D layered WSe2 crystal changed from diamagnetic to ferromagnetic after Ni-doping at all tested temperatures. Moreover, first principle density functional theory (DFT) calculations further confirmed the origin of room temperature ferromagnetism of Ni-doped WSe2, where the d-orbitals of the doped Ni atom promoted the spin moment and thus largely contributed to the magnetism change in the 2D layered material.

Self-Aligned Growth of Organic Semiconductor Single Crystals by Electric Field.

Science.gov (United States)

Kotsuki, Kenji; Obata, Seiji; Saiki, Koichiro

2016-01-19

We proposed a novel but facile method for growing organic semiconductor single-crystals via solvent vapor annealing (SVA) under electric field. In the conventional SVA growth process, nuclei of crystals appeared anywhere on the substrate and their crystallographic axes were randomly distributed. We applied electric field during the SVA growth of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) on the SiO2/Si substrate on which a pair of electrodes had been deposited beforehand. Real-time observation of the SVA process revealed that rodlike single crystals grew with their long axes parallel to the electric field and bridged the prepatterned electrodes. As a result, C8-BTBT crystals automatically formed a field effect transistor (FET) structure and the mobility reached 1.9 cm(2)/(V s). Electric-field-assisted SVA proved a promising method for constructing high-mobility single-crystal FETs at the desired position by a low-cost solution process.

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

KAUST Repository

Peng, Wei

2017-01-01

Despite their outstanding charge transport characteristics, organolead halide perovskite single crystals grown by hitherto reported crystallization methods are not suitable for most optoelectronic devices due to their small aspect ratios

Single-crystal growth of ceria-based materials; Einkristallzuechtung von Materialien auf der Basis von Cerdioxid

Energy Technology Data Exchange (ETDEWEB)

Ulbrich, Gregor

2015-07-23

In this work it could be shown that Skull-Melting is a suitable method for growing ceria single crystals. Twenty different ceria-based single crystals could be manufactured. It was possible to dope ceria single crystals with Gd, Sm, Y, Zr, Ti, Ta, and Pr in different concentrations. Also co-doping with the named metals was realized. However, there remain some problems for growing ceria-based single crystals by Skull-Melting. As ignition metal zirconium was used because no ceria-based material works well. For that reason all single crystals show small zirconium contamination. Another problem is the formation of oxygen by the heat-induced reduction of ceria during the melting process. Because of that the skull of sintered material is often destroyed by gas pressure. This problem had to be solved individually for every single crystal. The obtained single crystals were characterized using different methods. To ensure the single crystal character the y were examined by Laue diffraction. All manufactured crystals are single crystals. Also powder diffraction patterns of the milled and oxidized samples were measured. For the determination of symmetry and metric the structural parameters were analyzed by the Rietveld method. All synthesized materials crystallize in space group Fm-3m known from calcium fluoride. The cubic lattice parameter a was determined for all crystals. In the case of series with different cerium and zirconium concentrations a linear correlation between cerium content and cubic lattice parameter was detected. The elemental composition was determined by WDX. All crystals show a homogeneous elemental distribution. The oxygen content was calculated because the WDX method isn't useful for determination.

Growth and characterization of air annealing Mn-doped YAG:Ce single crystal for LED

International Nuclear Information System (INIS)

Xiang, Weidong; Zhong, Jiasong; Zhao, Yinsheng; Zhao, Binyu; Liang, Xiaojuan; Dong, Yongjun; Zhang, Zhimin; Chen, Zhaoping; Liu, Bingfeng

2012-01-01

Highlights: ► The YAG:Ce,Mn single crystal was well synthesized by the Czochralski (CZ) method. ► The emission intensity of the sample has been influenced after annealing. ► Annealed in the air at 1200 °C was the most optimal annealing condition. ► 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.

Growth of methyl 2-(2,4-dinitrophenyl)aminopropanoate single crystals

Science.gov (United States)

Perigaud, A.; Nicolau, Y. F.

1986-12-01

Methyl 2-(2,4-dinitrophenyl)aminopropanoate single crystals, 1 cm in diameter and 7 cm in length have been grown by a travelling-heater-Bridgman method in polyethylene tubes introduced into glass ampoules, at a growth rate of 1.5-6 mm/day. The starting material was synthesised and purified by recrystallization from methanol and by vacuum evaporation to a purity of 99.994%. The period of growth, and hence the length of the crystal, is limited due to melt decomposition and polycondensation. The b-axis of the crystals is always oriented at about 72° to the ampoule axis. Good quality single crystals have been obtained giving a FWHM of the Cu Kα (040) rocking curve of about 1'.

Radiation-damage recovery in undoped and oxidized Li doped Mg O crystals implanted with lithium ions

Energy Technology Data Exchange (ETDEWEB)

Alves, E. E-mail: ealves@itn.pt; Silva, R.C. da; Pinto, J.V.; Monteiro, T.; Savoini, B.; Caceres, D.; Gonzalez, R.; Chen, Y

2003-05-01

Undoped MgO and oxidized Li-doped MgO single crystals were implanted with 1 x 10{sup 17} Li{sup +}/cm{sup 2} at 175 keV. The Rutherford backscattering spectrometry (RBS)/channeling data obtained after implantation shows that damage was produced throughout the entire range of the implanted ions. Optical absorption measurements indicate that after implantation the most intense band occurs at {approx}5.0 eV, which has been associated with anion vacancies. After annealing at 450 K the intensity of the oxygen-vacancy band decreases monotonically with temperature and completely disappears at 950 K. A broad extinction band centered at {approx}2.14 eV associated with lithium precipitates emerges gradually and anneals out at 1250 K. RBS/channeling shows that recovery of the implantation damage is completed after annealing the oxidized samples at 1250 K.

Annealing effect on superconductivity of La2CuO4 single crystals

International Nuclear Information System (INIS)

Tanaka, I.; Takahashi, H.; Kojima, H.

1992-01-01

This paper reports that La 2 CuO 4 single crystals grown at an oxygen pressure of 0.2 MPa by TSFZ method are superconducting below 32 K, and show a semiconducting behavior in nonsuperconducting state. The single crystals of La 2 CuO 4 are changed from superconductors to semiconductors by annealing in argon, and are returned to superconductors by annealing at ambient pressure of oxygen. Therefore, superconductivity of the La 2 CuO 4 single crystals is due to excess oxygen

Annealing effect on superconductivity of La2CuO4 single crystals

International Nuclear Information System (INIS)

Tanaka, L.; Takahashi, H.; Kojima, H.

1992-01-01

La 2 CuO 4 single crystals grown at an oxygen pressure of 0.2 MPa by TSFZ method are superconducting below 32 K, and show a semiconducting behavior in nonsuperconducting state. The single crystals of La 2 CuO 4 are changed from superconductors to semiconductors by annealing in argon, and are returned to superconductors by annealing at ambient pressure of oxygen. Therefore, superconductivity of the La 2 CuO 4 single crystals is due to excess oxygen. (orig.)

Hopping conduction in gamma-irradiated InSe and InSe:Sn single crystals

International Nuclear Information System (INIS)

MUSTAFAEVA, S.N.; ISMAILOV, A.A.; ASADOV, M.M.

2010-01-01

Full text : The semiconductive InSe layer compound is characterized by a strong covalent bond inside the layers and a weak Van der Waals bonding between them. It was shown that across the layers of InSe single crystals at low temperatures (T ≤ 200 K) at direct current (dc) hopping conduction through localized states near the Fermi level takes place. The results of dc-conductivity of gamma-irradiated p-InSe and n-InSe : Sn layer single crystals have been presented in this work. ρ-InSe single crystal specimens grown by the Bridgman method were used in the experiments. Plates of the crystals under study were obtained by cleaving along the layers of single crystal ingots. The single-crystal InSe samples for electric measurements had the form of planar capacitors normal to the C axis of the crystals, with silver-paste electrodes. The thickness of the InSe samples was 300 mkm. Co 60 serves as the source of irradiation with energy of gamma-quantum equal to 1.3 MeV. The electric properties of non-irradiated and gamma-irradiated InSe crystals were measured under the same conditions. It is revealed that InSe and InSe : Sn (0.2 and 0.4 mole percent Sn) single crystals exhibit a variable range hopping conduction along a normal to their natural layers at temperatures T≤200 K in a dc electric field. From experimental data the parameters of localized states of p-InSe and n-InSe : Sn were calculated before and after gamma-irradiation. It is revealed that gamma-irradiation of p-InSe and n-InSe : Sn (0.2 and 0.4 mole percent Sn) single crystals leads to significant change of localized states parameters. After gamma-irradiation the density of states near the Fermi level increased, but their energy spread and the average jump distance decreased. The concentrations of radiated defects were estimated in p-InSe (5.18*10 1 7 sm - 3) and n-InSe : Sn (2.5*10 1 7 - 2.7*10 1 8 sm - 3) single crystals. The present results demonstrate that gamma-irradiation offers the possibility of tuning

Trapezoidal diffraction grating beam splitters in single crystal diamond

Science.gov (United States)

Kiss, Marcell; Graziosi, Teodoro; Quack, Niels

2018-02-01

Single Crystal Diamond has been recognized as a prime material for optical components in high power applications due to low absorption and high thermal conductivity. However, diamond microstructuring remains challenging. Here, we report on the fabrication and characterization of optical diffraction gratings exhibiting a symmetric trapezoidal profile etched into a single crystal diamond substrate. The optimized grating geometry diffracts the transmitted optical power into precisely defined proportions, performing as an effective beam splitter. We fabricate our gratings in commercially available single crystal CVD diamond plates (2.6mm x 2.6mm x 0.3mm). Using a sputter deposited hard mask and patterning by contact lithography, the diamond is etched in an inductively coupled oxygen plasma with zero platen power. The etch process effectively reveals the characteristic {111} diamond crystal planes, creating a precisely defined angled (54.7°) profile. SEM and AFM measurements of the fabricated gratings evidence the trapezoidal shape with a pitch of 3.82μm, depth of 170 nm and duty cycle of 35.5%. Optical characterization is performed in transmission using a 650nm laser source perpendicular to the sample. The recorded transmitted optical power as function of detector rotation angle shows a distribution of 21.1% in the 0th order and 23.6% in each +/-1st order (16.1% reflected, 16.6% in higher orders). To our knowledge, this is the first demonstration of diffraction gratings with trapezoidal profile in single crystal diamond. The fabrication process will enable beam splitter gratings of custom defined optical power distribution profiles, while antireflection coatings can increase the efficiency.

Co{sub 2}FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

Energy Technology Data Exchange (ETDEWEB)

Belmeguenai, M., E-mail: belmeguenai.mohamed@univ-paris13.fr; Tuzcuoglu, H.; Zighem, F.; Chérif, S. M.; Moch, P. [LSPM (CNRS-UPR 3407), 99 avenue Jean-Baptiste Clément, Université Paris 13, 93430 Villetaneuse (France); Gabor, M. S., E-mail: mihai.gabor@phys.utcluj.ro; Petrisor, T. [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Str. Memorandumului No. 28 RO-400114 Cluj-Napoca (Romania); Tiusan, C. [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Str. Memorandumului No. 28 RO-400114 Cluj-Napoca (Romania); Institut Jean Lamour, CNRS, Université de Nancy, BP 70239, F–54506 Vandoeuvre (France)

2014-01-28

10 nm and 50 nm Co{sub 2}FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (T{sub a}), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing T{sub a}, while the uniaxial anisotropy field is nearly unaffected by T{sub a} within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with T{sub a}. Finally, the FMR linewidth decreases when increasing T{sub a}, due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10{sup −3} and 1.3×10{sup −3} for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively)

Young's Modulus of Single-Crystal Fullerene C Nanotubes

Directory of Open Access Journals (Sweden)

Tokushi Kizuka

2012-01-01

Full Text Available We performed bending tests on single-crystal nanotubes composed of fullerene C70 molecules by in situ transmission electron microscopy with measurements of loading forces by an optical deflection method. The nanotubes with the outer diameters of 270–470 nm were bent using simple-beam and cantilever-beam loading by the piezomanipulation of silicon nanotips. Young's modulus of the nanotubes increased from 61 GPa to 110 GPa as the outer diameter decreased from 470 nm to 270 nm. Young's modulus was estimated to be 66% of that of single-crystal C60 nanotubes of the same outer diameter.

Use of porous MgO in pyrochemical applications

International Nuclear Information System (INIS)

Maiya, P.S.; Sweeney, S.M.; Carroll, L.A.; Dusek, J.T.

1994-11-01

Pyrochemical methods for the extraction of transuranic elements from light water reactor spent fuel require a reduction step in which the oxide fuel is reduced to metals by Li in molten LiCl. The Li 2 O formed is electrolytically reduced to metal in a cell that uses a carbon (or inert) anode and a Li cathode to recycle the salt and minimize the waste. Use of a carbon anode causes carbon dust that interferes with the process. Moreover, current efficiency is reduced as a result of oxidation of Li to Li 2 O by CO 2 . A porous MgO shroud around the anode was found to obviate these problems. Porous MgO crucibles and rectangular bar specimens were fabricated from MgO powders (electrically fused MgO, reagent grade MgO were mixed in appropriate combinations with a binder and lubricant). Particle size, force applied to the powders during cold pressing, and sintering temperature were varied to achieve a total porosity of >45% (mostly open porosity) and to control pore size and pore distribution. Mercury intrusion porosimetry was used to determine the pore size and pore size distribution. Flexural strength is observed to be proportional to the square root of pore size, which is consistent with fracture mechanics

Growth and characterization of 2-Methylimidazolium D-tartrate single crystal

Science.gov (United States)

Srinivasan, T. P.; Anandhi, S.; Gopalakrishnan, R.

2011-03-01

Single crystal of 2-Methylimidazolium D-tartrate (2MImdT; C8N2O6H12) has been grown by slow evaporation solution growth technique at room temperature using mixed solvents of ethanol and deionized water. Single crystal X-ray diffraction study confirms that 2-Methylimidazolium D-tartrate belongs to monoclinic crystal system with non-centrosymmetric space group P21. The Fourier transform infrared spectrum of 2-Methylimidazolium D-tartrate reveals the presence of methyl and carboxyl functional groups in the compound. The mechanical properties of 2MImdT crystal were studied. The theoretical factor group analysis predicts 168 optical modes in the title compound. The dielectric behavior of 2MImdT crystals was studied at different frequencies and temperatures. Decomposition and melting point of 2MImdT were found using thermal measurements. SHG behavior of the title compound was demonstrated using Q-switched Nd:YAG laser.

Bulk crystal growth and their effective third order nonlinear optical properties of 2-(4-fluorobenzylidene) malononitrile (FBM) single crystal

Science.gov (United States)

Priyadharshini, A.; Kalainathan, S.

2018-04-01

2-(4-fluorobenzylidene) malononitrile (FBM), an organic third order nonlinear (TONLO) single crystal with the dimensions of 32 × 7 × 11 mm3, has been successfully grown in acetone solution by slow evaporation technique at 35 °C. The crystal system (triclinic), space group (P-1) and crystalline purity of the titular crystal were measured by single crystal and powder X-ray diffraction, respectively. The molecular weight and the multiple functional groups of the FBM material were confirmed through the mass and FT-IR spectral analysis. UV-Vis-NIR spectral study enroles that the FBM crystal exhibits excellent transparency (83%) in the entire visible and near infra-red region with a wide bandgap 2.90 eV. The low dielectric constant (εr) value of FBM crystal is appreciable for microelectronics industry applications. Thermal stability and melting point (130.09 °C) were ascertained by TGA-DSC analysis. The laser-induced surface damage threshold (LDT) value of FBM specimen is found to be 2.14 GW/cm2, it is fairly good compared to other reported NLO crystals. The third - order nonlinear optical character of the FBM crystal was confirmed through the typical single beam Z-scan technique. All these finding authorized that the organic crystal of FBM is favorably suitable for NLO applications.

Annealing effect of H+ -implanted single crystal silicon on strain and crystal structure

International Nuclear Information System (INIS)

Duo Xinzhong; Liu Weili; Zhang Miao; Gao Jianxia; Fu Xiaorong; Lin Chenglu

2000-01-01

The work focuses on the rocking curves of H + -implanted single silicon crystal detected by Four-Crystal X-ray diffractometer. The samples were annealed under different temperatures. Lattice defect in H + -implanted silicon crystals was detected by Rutherford Backscattering Spectrometry. It appeared that H-related complex did not crush until annealing temperature reached about 400 degree C. At that temperature H 2 was formed, deflated in silicon lattice and strained the lattice. But defects did not come into being in large quantity. The lattice was undamaged. When annealing temperature reached 500 degree C, strain induced by H 2 deflation crashed the silicon lattice. A large number of defects were formed. At the same time bubbles in the crystal and blister/flaking on the surface could be observed

MgO nanoparticles as antibacterial agent: preparation and activity

Energy Technology Data Exchange (ETDEWEB)

Tang, Zhen-Xing, E-mail: tangzhenxing@126.com [Department of Food Science, Anqing, Vocational and Technical College, Anqing, Anhui (China); Lv, Bin-Feng [Date Palm Research Center, King Faisal University, (Saudi Arabia)

2014-07-15

Bacterial pollution is a great risk for human health. Nanotechnology offers a way to develop new inorganic antibacterial agents. Nano-inorganic metal oxide has a potential to reduce bacterial contamination. MgO is an important inorganic oxide and has been widely used in many fields. Many studies have shown that MgO nanoparticles have good antibacterial activity. Therefore, in this paper, the main synthesis methods, antibacterial activity and antibacterial mechanisms of MgO nanoparticles are reviewed. (author)

MgO nanoparticles as antibacterial agent: preparation and activity

International Nuclear Information System (INIS)

Tang, Zhen-Xing; Lv, Bin-Feng

2014-01-01

Bacterial pollution is a great risk for human health. Nanotechnology offers a way to develop new inorganic antibacterial agents. Nano-inorganic metal oxide has a potential to reduce bacterial contamination. MgO is an important inorganic oxide and has been widely used in many fields. Many studies have shown that MgO nanoparticles have good antibacterial activity. Therefore, in this paper, the main synthesis methods, antibacterial activity and antibacterial mechanisms of MgO nanoparticles are reviewed. (author)

Synthesis, growth, crystal structure, optical and third order nonlinear optical properties of quinolinium derivative single crystal: PNQI

Science.gov (United States)

Karthigha, S.; Krishnamoorthi, C.

2018-03-01

An organic quinolinium derivative nonlinear optical (NLO) crystal, 1-ethyl-2-[2-(4-nitro-phenyl)-vinyl]-quinolinium iodide (PNQI) was synthesized and successfully grown by slow evaporation solution growth technique. Formation of a crystalline compound was confirmed by single crystal X-ray diffraction. The quinolinium compound PNQI crystallizes in the triclinic crystal system with a centrosymmetric space group of P-1 symmetry. The molecular structure of PNQI was confirmed by 1H NMR and 13C NMR spectral studies. The thermal properties of the crystal have been investigated by thermogravimetric (TG) and differential scanning calorimetry (DSC) studies. The optical characteristics obtained from UV-Vis-NIR spectral data were described and the cut-off wavelength observed at 506 nm. The etching study was performed to analyse the growth features of PNQI single crystal. The third order NLO properties such as nonlinear refractive index (n2), nonlinear absorption coefficient (β) and nonlinear susceptibility (χ (3)) of the crystal were investigated using Z-scan technique at 632.8 nm of Hesbnd Ne laser.

Preparation of MgO Films as Buffer Layers by Laser-ablation at Various Substrate Temperatures

Institute of Scientific and Technical Information of China (English)

LI Ling; WANG Chuanbin; WANG Fang; SHEN Qiang; ZHANG Lianmeng

2011-01-01

MgO thin films were deposited on Si(100) substrates by laser ablation under various substrate temperatures (Tsub),expecting to provide a candidate buffer layer for the textured growth of functional perovskite oxide films on Si substrates.The effect of Tsub on the preferred orientation,crystallinity and surface morphology of the films was investigated.MgO films in single-phase were obtained at 473-973 K.With increasing Tsub,the preferred orientation of the films changed from (200) to (111).The crystallinity and surface morphology was different too,depending on Tsub·At Tsub=673 K,the MgO film became uniform and smooth,exhibiting high crystallinity and a dense texture.

Steady-state crack growth in single crystals under Mode I loading

DEFF Research Database (Denmark)

Juul, Kristian Jørgensen; Nielsen, Kim Lau; Niordson, Christian Frithiof

2017-01-01

The active plastic zone that surrounds the tip of a sharp crack growing under plane strain Mode I loading conditions at a constant velocity in a single crystal is studied. Both the characteristics of the plastic zone and its effect on the macroscopic toughness is investigated in terms of crack tip...... that the largest shielding effect develops in HCP crystals, while the lowest shielding exists for FCC crystals. Rate-sensitivity is found to affect the plastic zone size, but the characteristics overall remain similar for each individual crystal structure. An increasing rate-sensitivity at low crack velocities...... shielding due to plasticity (quantified by employing the Suo, Shih, and Varias set-up). Three single crystals (FCC, BCC, HCP) are modelled in a steady-state elastic visco-plastic framework, with emphasis on the influence of rate-sensitivity and crystal structures. Distinct velocity discontinuities...

Colour centre-free perovskite single crystals

International Nuclear Information System (INIS)

Petit, Pierre-Olivier; Petit, Johan; Goldner, Philippe; Viana, Bruno

2009-01-01

Yb 3+ :YAlO 3 (YAP) and Yb 3+ :GdAlO 3 (GAP) are interesting 1 μm high-power laser media thanks to their very good thermo-mechanical properties. However, as-grown perovskite single crystals exhibit colour centres. Parasitic thermal load generated by these centres is deleterious for high-power laser action and can lead to crystal damages. Moreover these defects decrease Yb 3+ lifetime. They are related to trapped holes on the oxygen network. In the present work, several schemes to remove colour centres are presented. Attention is focused on cerium codoping, thermal annealing under reducing atmosphere and growth of non-stoechiometric compounds.

Radiation effects in corundum single crystals

International Nuclear Information System (INIS)

Gevorkyan, V.A.; Harutunyan, V.V.; Hakhverdyan, E.A.

2005-01-01

On the basis of new experimental results and analysis of publications it is shown that in the lattice of corundum crystals the high-energy particles create stable structural defects due to knocking out of atoms from normal sites of the anionic sublattice; this leads to the formation of F and F '+ centers as well as to other complex [Al i '+ F] type color centers. The essence of 'radiation memory' effect in corundum single crystals is that the high-energy particles irradiation, annealing at high temperatures and additional irradiation by X-rays result in the restoration of some spectral bands of the optical absorption in the range 200-650 nm

Synthesis and structural characterization of bulk Sb2Te3 single crystal

Science.gov (United States)

Sultana, Rabia; Gahtori, Bhasker; Meena, R. S.; Awana, V. P. S.

2018-05-01

We report the growth and characterization of bulk Sb2Te3 single crystal synthesized by the self flux method via solid state reaction route from high temperature melt (850˚C) and slow cooling (2˚C/hour) of constituent elements. The single crystal X-ray diffraction pattern showed the 00l alignment and the high crystalline nature of the resultant sample. The rietveld fitted room temperature powder XRD revealed the phase purity and rhombohedral structure of the synthesized crystal. The formation and analysis of unit cell structure further verified the rhombohedral structure composed of three quintuple layers stacked one over the other. The SEM image showed the layered directional growth of the synthesized crystal carried out using the ZEISS-EVOMA-10 scanning electron microscope The electrical resistivity measurement was carried out using the conventional four-probe method on a quantum design Physical Property Measurement System (PPMS). The temperature dependent electrical resistivity plot for studied Sb2Te3 single crystal depicts metallic behaviour in the absence of any applied magnetic field. The synthesis as well as the structural characterization of as grown Sb2Te3 single crystal is reported and discussed in the present letter.

Buffer-layer enhanced crystal growth of BaB6 (1 0 0) thin films on MgO (1 0 0) substrates by laser molecular beam epitaxy

International Nuclear Information System (INIS)

Kato, Yushi; Yamauchi, Ryosuke; Arai, Hideki; Tan, Geng; Tsuchimine, Nobuo; Kobayashi, Susumu; Saeki, Kazuhiko; Takezawa, Nobutaka; Mitsuhashi, Masahiko; Kaneko, Satoru; Yoshimoto, Mamoru

2012-01-01

Crystalline BaB 6 (1 0 0) thin films can be fabricated on MgO (1 0 0) substrates by inserting a 2-3 nm-thick epitaxial SrB 6 (1 0 0) buffer layer by pulsed laser deposition (PLD) in ultra-high vacuum (i.e., laser molecular beam epitaxy). Reflection high-energy electron diffraction and X-ray diffraction measurements indicated the heteroepitaxial structure of BaB 6 (1 0 0)/SrB 6 (1 0 0)/MgO (1 0 0) with the single domain of the epitaxial relationship. Conversely, BaB 6 thin films without the buffer layer were not epitaxial instead they developed as polycrystalline films with a random in-plane configuration and some impurity phases. As a result, the buffer layer is considered to greatly affect the initial growth of epitaxial BaB 6 thin films; therefore, in this study, buffering effects have been discussed. From the conventional four-probe measurement, it was observed that BaB 6 epitaxial thin films exhibit n-type semiconducting behavior with a resistivity of 2.90 × 10 -1 Ω cm at room temperature.

Crystal-field analysis of U3+ ions in K2LaX5 (X=Cl, Br or I) single crystals

Science.gov (United States)

Karbowiak, M.; Edelstein, N.; Gajek, Z.; Drożdżyński, J.

1998-11-01

An analysis of low temperature absorption spectra of U3+ ions doped in K2LaX5 (X=Cl, Br or I) single crystals is reported. The energy levels of the U3+ ion in the single crystals were assigned and fitted to a semiempirical Hamiltonian representing the combined atomic and crystal-field interactions at the Cs symmetry site. An analysis of the nephelauxetic effect and crystal-field splittings in the series of compounds is also reported.

Encapsulation of nanoparticles into single-crystal ZnO nanorods and microrods.

Science.gov (United States)

Liu, Jinzhang; Notarianni, Marco; Rintoul, Llew; Motta, Nunzio

2014-01-01

One-dimensional single crystal incorporating functional nanoparticles of other materials could be an interesting platform for various applications. We studied the encapsulation of nanoparticles into single-crystal ZnO nanorods by exploiting the crystal growth of ZnO in aqueous solution. Two types of nanodiamonds with mean diameters of 10 nm and 40 nm, respectively, and polymer nanobeads with size of 200 nm have been used to study the encapsulation process. It was found that by regrowing these ZnO nanorods with nanoparticles attached to their surfaces, a full encapsulation of nanoparticles into nanorods can be achieved. We demonstrate that our low-temperature aqueous solution growth of ZnO nanorods do not affect or cause degradation of the nanoparticles of either inorganic or organic materials. This new growth method opens the way to a plethora of applications combining the properties of single crystal host and encapsulated nanoparticles. We perform micro-photoluminescence measurement on a single ZnO nanorod containing luminescent nanodiamonds and the spectrum has a different shape from that of naked nanodiamonds, revealing the cavity effect of ZnO nanorod.

MgO by injection CVD

International Nuclear Information System (INIS)

Abrutis, A.; Kubilius, V.; Teiserkis, A.; Bigelyte, V.; Vengalis, B.; Jukna, A.; Butkute, R.

1997-01-01

Epitaxial YBa 2 Cu 3 O 7 layers with 45 in-plane orientation have been grown by injection CVD on MgO substrates polished off-axis to within 1.4-1.9 of the [100] direction. This new single-source CVD process is based on computer-controlled injection of precise microdoses of a metal-organic precursor solution into a CVD reactor. A wide range of solution compositions was tested to investigate compositional effects on phase purity, surface morphology, texturing and superconducting properties of the prepared films. The highest quality films with pure 45 texture had a smooth surface, zero resistance T c (R=0) of 88-89 K, and critical current density J c (77 K) above 10 6 A/cm 2 . (orig.) and critical current density J c (77 K) above 10 6 A/cm 2 . (orig.)

Method for single crystal growth of photovoltaic perovskite material and devices

Science.gov (United States)

Huang, Jinsong; Dong, Qingfeng

2017-11-07

Systems and methods for perovskite single crystal growth include using a low temperature solution process that employs a temperature gradient in a perovskite solution in a container, also including at least one small perovskite single crystal, and a substrate in the solution upon which substrate a perovskite crystal nucleates and grows, in part due to the temperature gradient in the solution and in part due to a temperature gradient in the substrate. For example, a top portion of the substrate external to the solution may be cooled.

Single-crystal charge transfer interfaces for efficient photonic devices (Conference Presentation)

Science.gov (United States)

Alves, Helena; Pinto, Rui M.; Maçôas, Ermelinda M. S.; Baleizão, Carlos; Santos, Isabel C.

2016-09-01

Organic semiconductors have unique optical, mechanical and electronic properties that can be combined with customized chemical functionality. In the crystalline form, determinant features for electronic applications such as molecular purity, the charge mobility or the exciton diffusion length, reveal a superior performance when compared with materials in a more disordered form. Combining crystals of two different conjugated materials as even enable a new 2D electronic system. However, the use of organic single crystals in devices is still limited to a few applications, such as field-effect transistors. In 2013, we presented the first system composed of single-crystal charge transfer interfaces presenting photoconductivity behaviour. The system composed of rubrene and TCNQ has a responsivity reaching 1 A/W, corresponding to an external quantum efficiency of nearly 100%. A similar approach, with a hybrid structure of a PCBM film and rubrene single crystal also presents high responsivity and the possibility to extract excitons generated in acceptor materials. This strategy led to an extended action towards the near IR. By adequate material design and structural organisation of perylediimides, we demonstrate that is possible to improve exciton diffusion efficiency. More recently, we have successfully used the concept of charge transfer interfaces in phototransistors. These results open the possibility of using organic single-crystal interfaces in photonic applications.

Synthesis and photocatalytic activity of mesoporous – (001) facets TiO_2 single crystals

International Nuclear Information System (INIS)

Dong, Yeshuo; Fei, Xuening; Zhou, Yongzhu

2017-01-01

Highlights: • The (001) facets of TiO_2 single crystals with mesoporous structure. • The (010) and (100) facets of TiO_2 single crystals were covered by the flower – shaped TiO_2 crystals. • This special structure could promote charge separation and provide more active sites, which will lead to a substantial increase in photocatalytic activity. - Abstract: In this work, the mesoporous – (001) facets TiO_2 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 TiO_2 single crystals, we synthesized these mesoporous – (001) facets TiO_2 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 TiO_2 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 TiO_2 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 TiO_2 single crystals.

Neutron transmission of single-crystal sapphire filters

International Nuclear Information System (INIS)

Adib, M.; Kilany, M.; Habib, N.; Fathallah, M.

2004-01-01

A simple additive formula is given that permits the calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-sections as a function of sapphire temperature and crystal parameters. We have developed a computer program that allows calculations of the thermal neutron transmission for the sapphire rhombohedral structure and its equivalent trigonal structure. The calculated total cross-section values and effective attenuation coefficient for mono-crystalline sapphire at different temperatures are compared with measured values. Overall agreement is indicated between the formula fits and experimental data. We discuss the use of sapphire single-crystal as a thermal neutron filter in terms of the optimum crystal thickness, mosaic spread, temperature, cutting plane and tuning for efficient transmission of thermal-reactor neutrons

Microscopic single-crystal refractometry as a function of wavelength

International Nuclear Information System (INIS)

DeLoach, L.D.

1994-01-01

The refractive indices of crystal fragments 50--200 μm in size can be measured for light wavelengths between 365 and 1100 nm with a spindle-stage refractometer. Established methods from optical crystallograpy are used to orient a crystal on the microscope spindle stage and then to match its refractive index to an immersion fluid. The refractive index of the fluid for the wavelength of light and matching temperature is determined by comparison of a reference crystal on a second spindle axis with the fluid under the match conditions. Investigations of new nonlinear-optical crystals admirably demonstrate the advantages of measuring the refractive index to ± 0.0004 in small single crystals

Evaporation mechanisms of MgO in laser assisted atom probe tomography

KAUST Repository

Mazumder, Baishakhi

2011-05-01

In this paper the field evaporation properties of bulk MgO and sandwiched MgO layers in Fe are compared using laser assisted Atom Probe Tomography. The comparison of flight time spectra gives an estimate of the evaporation times as a function of the wavelength and the laser energy. It is shown that the evaporation takes place in two steps on two different time scales in MgO. It is also shown that as long as the MgO layer is buried in Fe, the evaporation is dominated by the photon absorption in Fe layer at the tip apex. Eventually the evaporation process of MgO is discussed based on the difference between the bulk materials and the multilayer samples. © 2010 Elsevier B.V.

Evaporation mechanisms of MgO in laser assisted atom probe tomography

KAUST Repository

Mazumder, Baishakhi; Vella, Angela; Dé conihout, Bernard; Al-Kassab, Talaat

2011-01-01

In this paper the field evaporation properties of bulk MgO and sandwiched MgO layers in Fe are compared using laser assisted Atom Probe Tomography. The comparison of flight time spectra gives an estimate of the evaporation times as a function of the wavelength and the laser energy. It is shown that the evaporation takes place in two steps on two different time scales in MgO. It is also shown that as long as the MgO layer is buried in Fe, the evaporation is dominated by the photon absorption in Fe layer at the tip apex. Eventually the evaporation process of MgO is discussed based on the difference between the bulk materials and the multilayer samples. © 2010 Elsevier B.V.

AFM studies on heavy ion irradiated YBCO single crystals

International Nuclear Information System (INIS)

Lakhani, Archana; Marhas, M.K.; Saravanan, P.; Ganesan, V.; Srinivasan, R.; Kanjilal, D.; Mehta, G.K.; Elizabeth, Suja; Bhat, H.L.

2000-01-01

Atomic Force Microscopy (AFM) is extensively used to characterise the surface morphology of high energy ion irradiated single crystals of high temperature superconductor - YBCO. Our earlier systematic studies on thin films of YBCO under high energy and heavy ion irradiation shows clear evidence of ion induced sputtering or erosion, even though the effect is more on the grain boundaries. These earlier results were supported by electrical resistance measurements. In order to understand more clearly, the nature of surface modification at these high energies, AFM studies were carried out on single crystals of YBCO. Single crystals were chosen in order to see the effect on crystallites alone without interference from grain boundaries. 200 MeV gold ions were used for investigation using the facilities available at Nuclear Science Centre, New Delhi. The type of ion and the range of energies were chosen to meet the threshold for electronically mediated defect production. The results are in conformity with our earlier studies and will be described in detail in the context of electronic energy loss mediated sputtering or erosion. (author)

Observation of plastic deformation in freestanding single crystal Au nanowires

International Nuclear Information System (INIS)

Lee, Dongyun; Zhao Manhong; Wei Xiaoding; Chen Xi; Jun, Seong C.; Hone, James; Herbert, Erik G.; Oliver, Warren C.; Kysar, Jeffrey W.

2006-01-01

Freestanding single crystal nanowires of gold were fabricated from a single grain of pure gold leaf by standard lithographic techniques, with center section of 7 μm in length, 250 nm in width, and 100 nm in thickness. The ends remained anchored to a silicon substrate. The specimens were deflected via nanoindenter until plastic deformation was achieved. Nonlocalized and localized plastic deformations were observed. The resulting force-displacement curves were simulated using continuum single crystal plasticity. A set of material parameters which closely reproduce the experimental results suggests that the initial critical resolved shear stress was as high as 135 MPa

Relaxor-based ferroelectric single crystals: growth, domain engineering, characterization and applications

Science.gov (United States)

Sun, Enwei; Cao, Wenwu

2014-01-01

In the past decade, domain engineered relaxor-PT ferroelectric single crystals, including (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT), (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT) and (1-x-y)Pb(In1/2Nb1/2)O3-yPb(Mg1/3Nb2/3)O3-xPbTiO3 (PIN-PMN-PT), with compositions near the morphotropic phase boundary (MPB) have triggered a revolution in electromechanical devices owing to their giant piezoelectric properties and ultra-high electromechanical coupling factors. Compared to traditional PbZr1-xTixO3 (PZT) ceramics, the piezoelectric coefficient d33 is increased by a factor of 5 and the electromechanical coupling factor k33 is increased from 90%. Many emerging rich physical phenomena, such as charged domain walls, multi-phase coexistence, domain pattern symmetries, etc., have posed challenging fundamental questions for scientists. The superior electromechanical properties of these domain engineered single crystals have prompted the design of a new generation electromechanical devices, including sensors, transducers, actuators and other electromechanical devices, with greatly improved performance. It took less than 7 years from the discovery of larger size PMN-PT single crystals to the commercial production of the high-end ultrasonic imaging probe “PureWave”. The speed of development is unprecedented, and the research collaboration between academia and industrial engineers on this topic is truly intriguing. It is also exciting to see that these relaxor-PT single crystals are being used to replace traditional PZT piezoceramics in many new fields outside of medical imaging. The new ternary PIN-PMN-PT single crystals, particularly the ones with Mn-doping, have laid a solid foundation for innovations in high power acoustic projectors and ultrasonic motors, hinting another revolution in underwater SONARs and miniature actuation devices. This article intends to provide a comprehensive review on the development of relaxor-PT single crystals, spanning material discovery, crystal growth

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.

Cross-section of single-crystal materials used as thermal neutron filters

International Nuclear Information System (INIS)

Adib, M.

2005-01-01

Transmission properties of several single crystal materials important for neutron scattering instrumentation are presented. A computer codes are developed which permit the calculation of thermal diffuse and Bragg-scattering cross-sections of silicon., and sapphire as a function of material's constants, temperature and neutron energy, E, in the range 0.1 MeV .A discussion of the use of their single-crystal as a thermal neutron filter in terms of the optimum crystal thickness, mosaic spread, temperature, cutting plane and tuning for efficient transmission of thermal-reactor neutrons is given

X-ray diffraction microstructural analysis of bimodal size distribution MgO nano powder

International Nuclear Information System (INIS)

Suminar Pratapa; Budi Hartono

2009-01-01

Investigation on the characteristics of x-ray diffraction data for MgO powdered mixture of nano and sub-nano particles has been carried out to reveal the crystallite-size-related microstructural information. The MgO powders were prepared by co-precipitation method followed by heat treatment at 500 degree Celsius and 1200 degree Celsius for 1 hour, being the difference in the temperature was to obtain two powders with distinct crystallite size and size-distribution. The powders were then blended in air to give the presumably bimodal-size- distribution MgO nano powder. High-quality laboratory X-ray diffraction data for the powders were collected and then analysed using Rietveld-based MAUD software using the lognormal size distribution. Results show that the single-mode powders exhibit spherical crystallite size (R) of 20(1) nm and 160(1) nm for the 500 degree Celsius and 1200 degree Celsius data respectively with the nano metric powder displays narrower crystallite size distribution character, indicated by lognormal dispersion parameter of 0.21 as compared to 0.01 for the sub-nano metric powder. The mixture exhibits relatively more asymmetric peak broadening. Analysing the x-ray diffraction data for the latter specimen using single phase approach give unrealistic results. Introducing two phase models for the double-phase mixture to accommodate the bimodal-size-distribution characteristics give R = 100(6) and σ = 0.62 for the nano metric phase and R = 170(5) and σ= 0.12 for the σ sub-nano metric phase. (author)

Investigations of morphological changes during annealing of polyethylene single crystals

NARCIS (Netherlands)

Tian, M.; Loos, J.

2001-01-01

The morphological evolution of isolated individual single crystals deposited on solid substrates was investigated during annealing experiments using in situ and ex situ atomic force microscopy techniques. The crystal morphology changed during annealing at temperatures slightly above the original

Lattice dynamics at high pressure: application of inelastic X-ray scattering and ab-initio calculations -MgO at 35 GPa

International Nuclear Information System (INIS)

Ghose, Subrata

2006-01-01

Full text: Until recently, inelastic neutron scattering (INS) has been extensively used to study the phonon dispersion throughout the Brillouin zone and phonon density of states in crystalline materials. The weak interaction of neutrons with matter and the typical size of the neutron beams require the use of cm-size single crystals that puts an upper limit to the measurement of phonon dispersion at high pressure to about 10-15 Gpa by INS. Inelastic X-ray scattering (IXS) using third generation synchrotron sources now makes it possible to measure the phonon dispersion at high pressures up to 50 GP A in crystals tens of microns in size mounted in a diamond-anvil cell, usually using He as the pressure transmitting medium. We have used this technique to measure the longitudinal acoustic and optic phonon branches of MgO along the Γ-X direction at 35 Gpa. The experimentally observed phonon-branches are in remarkable agreement with ab-initio quantum mechanical calculations using the density-functional perturbation theory. The derived thermodynamic properties, such as specific heat and the entropy are in very good agreement with values obtained from a thermodynamically assessed data set

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) s...

Optical properties of Sulfur doped InP single crystals

Science.gov (United States)

El-Nahass, M. M.; Youssef, S. B.; Ali, H. A. M.

2014-05-01

Optical properties of InP:S single crystals were investigated using spectrophotometric measurements in the spectral range of 200-2500 nm. The absorption coefficient and refractive index were calculated. It was found that InP:S crystals exhibit allowed and forbidden direct transitions with energy gaps of 1.578 and 1.528 eV, respectively. Analysis of the refractive index in the normal dispersion region was discussed in terms of the single oscillator model. Some optical dispersion parameters namely: the dispersion energy (Ed), single oscillator energy (Eo), high frequency dielectric constant (ɛ∞), and lattice dielectric constant (ɛL) were determined. The volume and the surface energy loss functions (VELF & SELF) were estimated. Also, the real and imaginary parts of the complex conductivity were calculated.

Ferroelectric lead magnesium niobate-lead titanate single crystals for ultrasonic hydrophone applications

International Nuclear Information System (INIS)

Lau, S.T.; Lam, K.H.; Chan, H.L.W.; Choy, C.L.; Luo, H.S.; Yin, Q.R.; Yin, Z.W.

2004-01-01

Ferroelectric lead magnesium niobate-lead titanate (PMN-PT) single crystals with a composition around the rhombohedral-tetragonal morphotropic phase boundary (65 mol% of PMN) were used to fabricate single-element needle-type hydrophones for measuring the spatial and temporal characteristics of medical ultrasonic transducers. PMN-PT single crystal was grown by a modified Bridgman method. Discs (0.5 mm thick) with normal along the direction were cut and then poled by a dc field in the thickness direction. The single crystal has a high relative permittivity (ε r ∼4000) making it appropriate for small area hydrophone applications. Single-element needle-type hydrophones with this material as the sensing element have been fabricated and characterized. The hydrophones have flat frequency response and good receiving sensitivity over certain frequency range in the megahertz region

On the growth of calcium tartrate tetrahydrate single crystals

Indian Academy of Sciences (India)

Unknown

Abstract. Calcium tartrate single crystals were grown using silica gel as the growth medium. Calcium for- mate mixed with formic acid was taken as the supernatant solution. It was observed that the nucleation den- sity was reduced and the size of the crystals was improved to a large extent compared to the conventional way.

Four-fold magnetic anisotropy in a Co film on MgO(0 0 1)

International Nuclear Information System (INIS)

Pires, M.J.M.; Cotta, A.A.C.; Martins, M.D.; Silva, A.M.A.; Macedo, W.A.A.

2011-01-01

The development of devices based on magnetic tunnel junctions has raised new interests on the structural and magnetic properties of the interface Co/MgO. In this context, we have grown ultrathin Co films (≤30 A) by molecular-beam epitaxy on MgO(0 0 1) substrates kept at different temperatures (T S ). Their structural and magnetic properties were correlated and discussed in the context of distinct magnetic anisotropies for Co phases reported in the literature. The sample characterization has been done by reflection high energy electron diffraction, magneto-optical Kerr effect and ferromagnetic resonance. The main focus of the work is on a sample deposited at T S =25 o C, as its particular way of growth has enabled a bct Co structure to settle on the substrate, where it is not normally obtained without specific seed layers. This sample presented the best crystallinity, softer magnetic properties and a four-fold in-plane magnetic anisotropy with Co easy directions. Concerning the samples prepared at T S =200 and 500 o C, they show fcc and polycrystalline structures, respectively and more intricate magnetic anisotropy patterns. - Research Highlights: →Results suggest the lattice is already after the Bain transformation for T S =25 o C, and the Co film has a bct structure instead of an fct one. →For deposition temperature of T S =25 o C, a four-fold in-plane magnetic anisotropy with Co easy directions has been obtained. →The growth mode of Co on MgO single crystals at different temperatures resulted in bct Co at T S =25 o C, fcc Co at T S =200 o C and polycrystalline Co at T S =500 o C.

Commensurability oscillations in NdBa2Cu3Oy single crystals

Indian Academy of Sciences (India)

gated by angular dependent magnetization in very pure twinned and twin-free NdBa2 Cu3 Oy single ... The layered structure and the c-axis coherence length, ξc ≈ 4 ˚A, smaller than the lattice ... The high quality of both crystals is demonstrated by ... Commensurability oscillations in NdBa2Cu3Oy single crystals. 2. 3. 4. 5. 6.

Cryogenic motion performances of a piezoelectric single crystal micromotor

Science.gov (United States)

Li, Xiaotian; Wu, Yuting; Chen, Zhijiang; Wei, Xiaoyong; Luo, Haosu; Dong, Shuxiang

2014-04-01

This study investigates the cryogenic performances of a millimeter-size piezoelectric ultrasonic linear micromotor. The piezoelectric vibrator of the micromotor is made of Pb(In1/2Nb1/2)O3 -Pb(Mg1/3Nb2/3)-PbTiO3 single crystal and operated in first-bending wobbling mode. Experiments show that the piezoelectric single crystal micromotor works effectively even at extremely low temperature of -175 °C, although its resonance peaks vary with temperature significantly. This work confirms the feasibility of cryogenic operation of the piezo-micromotor, which is meaningful for aerospace or superconducting microwave application.

Preparation of single-crystal copper ferrite nanorods and nanodisks

International Nuclear Information System (INIS)

Du Jimin; Liu Zhimin; Wu Weize; Li Zhonghao; Han Buxing; Huang Ying

2005-01-01

This article, for the first time, reports the preparation of single-crystal copper ferrite nanorods and nanodisks. Using amorphous copper ferrite nanoparticles synthesized by reverse micelle as reaction precursor, single-crystal copper ferrite nanorods were synthesized via hydrothermal method in the presence of surfactant polyethylene glycol (PEG), however, copper ferrite nanodisks were prepared through the same procedures except the surfactant PEG. The resulting nanomaterials have been characterized by powder X-ray diffraction (XRD), selected electron area diffraction (SEAD), and transmission electron microscopy (TEM). The bulk composition of the samples was determined by means of X-ray photoelectron spectroscopy (XPS)

Synthesis and characterization of MgO nanocrystals for biosensing applications

Energy Technology Data Exchange (ETDEWEB)

Li, Hongji [Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry & Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Mingji, E-mail: limingji@163.com [Tianjin Key Laboratory of Film Electronic and Communication Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Qiu, Guojun [Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry & Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Cuiping; Qu, Changqing; Yang, Baohe [Tianjin Key Laboratory of Film Electronic and Communication Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China)

2015-05-25

Highlights: • MgO nanocrystals were prepared using DC arc plasma jet CVD method. • The growth time does not exceed 10 min in process of the synthesis. • The samples were found to consist of cubic MgO nanobelts and nanosheets. • Nanocrystals contain contacts, rough edges, vacancies, and doping defects. • The samples exhibited excellent electrochemical biosensing properties. - Abstract: MgO nanocrystals were prepared using a simple direct current arc plasma jet chemical vapor deposition method. Magnesium nitrate was used as source material and Mo film was used as a substrate and catalyst. The high-temperature plasma produced ensured rapid synthesis of the MgO nanocrystals. The as-prepared nanocrystals were characterized by field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, Fourier transform infrared spectrometry, ultraviolet–visible spectrophotometry, and photoluminescence measurements. The as-synthesized samples were found to consist of cubic MgO nanobelts and nanosheets with large surface areas and low coordination oxide ions, and contained numerous contacts, rough edges, vacancies, and doping defects. The nanostructures exhibited excellent electrochemical sensing properties with high-sensing sensitivity toward ascorbic acid. Their high electrocatalytic activity was attributed to the effect of defects and the surface electron transfer ability of the one-dimensional MgO nanobelts.

A hot implantation study on the evolution of defects in He ion implanted MgO(1 0 0)

International Nuclear Information System (INIS)

Fedorov, A.V.; Huis, M.A. van; Veen, A. van

2002-01-01

Ion implantation at elevated temperature, so-called hot implantation, was used to study nucleation and thermal stability of the defects. In this work, MgO(1 0 0) single crystal samples were implanted with 30 keV He ions at various implantation temperatures. The implantation doses ranged from 10 14 to 10 16 cm -2 . The implantation introduced defects were subsequently studied by thermal helium desorption spectroscopy (THDS) and Doppler broadening positron beam analysis (PBA). The THDS study provides vital information on the kinetics of He release from the sample. PBA technique, being sensitive to the open volume defects, provides complementary information on cavity evolution. The THD study has shown that in most cases helium release is characterised by the activation energy of Q=4.7±0.5 eV with the maximum release temperature of T max =1830 K. By applying first order desorption model the pre-exponent factor is estimated as ν=4.3x10 11 s -1

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.

Reversible conversion of valence-tautomeric copper metal-organic frameworks dependent single-crystal-to-single-crystal oxidation/reduction: a redox-switchable catalyst for C-H bonds activation reaction.

Science.gov (United States)

Huang, Chao; Wu, Jie; Song, Chuanjun; Ding, Ran; Qiao, Yan; Hou, Hongwei; Chang, Junbiao; Fan, Yaoting

2015-06-28

Upon single-crystal-to-single-crystal (SCSC) oxidation/reduction, reversible structural transformations take place between the anionic porous zeolite-like Cu(I) framework and a topologically equivalent neutral Cu(I)Cu(II) mixed-valent framework. The unique conversion behavior of the Cu(I) framework endowed it as a redox-switchable catalyst for the direct arylation of heterocycle C-H bonds.

Surface relief grating formation on a single crystal of 4-(dimethylamino)azobenzene

International Nuclear Information System (INIS)

Nakano, Hideyuki; Tanino, Takahiro; Shirota, Yasuhiko

2005-01-01

Surface relief grating (SRG) formation on an organic single crystal by irradiation with two coherent laser beams has been demonstrated by using 4-(dimethylamino)azobenzene (DAAB). It was found that the SRG formation was greatly depending upon both the coordination of the crystal and the polarization of the writing beams. The dependence of the polarization of writing beams on the SRG formation using the single crystal was found to be quite different from that reported for amorphous polymers and photochromic amorphous molecular materials, suggesting that the mechanism of the SRG formation on the organic crystal is somewhat different from that on amorphous materials

Encapsulation of nanoparticles into single-crystal ZnO nanorods and microrods

Directory of Open Access Journals (Sweden)

Jinzhang Liu

2014-04-01

Full Text Available One-dimensional single crystal incorporating functional nanoparticles of other materials could be an interesting platform for various applications. We studied the encapsulation of nanoparticles into single-crystal ZnO nanorods by exploiting the crystal growth of ZnO in aqueous solution. Two types of nanodiamonds with mean diameters of 10 nm and 40 nm, respectively, and polymer nanobeads with size of 200 nm have been used to study the encapsulation process. It was found that by regrowing these ZnO nanorods with nanoparticles attached to their surfaces, a full encapsulation of nanoparticles into nanorods can be achieved. We demonstrate that our low-temperature aqueous solution growth of ZnO nanorods do not affect or cause degradation of the nanoparticles of either inorganic or organic materials. This new growth method opens the way to a plethora of applications combining the properties of single crystal host and encapsulated nanoparticles. We perform micro-photoluminescence measurement on a single ZnO nanorod containing luminescent nanodiamonds and the spectrum has a different shape from that of naked nanodiamonds, revealing the cavity effect of ZnO nanorod.

UV detectors based on epitaxial diamond films grown on single-crystal diamond substrates by vapor-phase synthesis

International Nuclear Information System (INIS)

Sharonov, G.V.; Petrov, S.A.; Bol'shakov, A.P.; Ral'chenko, V.G.; Kazyuchits, N.M.

2010-01-01

The prospects for use of CVD-technology for epitaxial growth of single-crystal diamond films of instrumental quality in UHF plasma for the production of optoelectronic devices are discussed. A technology for processing diamond single crystals that provides a perfect surface crystal structure with roughness less than 0,5 nm was developed. It was demonstrated that selective UV detectors based on synthetic single-crystal diamond substrates coated with single-crystal films can be produced. A criterion for selecting clean and structurally perfect single crystals of synthetic diamond was developed for the epitaxial growth technology. (authors)

Blue luminescence in Tm3+-doped KGd(WO4)2 single crystals

International Nuclear Information System (INIS)

Gueell, F.; Mateos, X.; Gavalda, Jna.; Sole, R.; Aguilo, M.; Diaz, F.; Massons, J.

2004-01-01

Up-conversion blue emissions of trivalent thulium ions in monoclinic KGd(WO 4 ) 2 single crystals at 454 and 479 nm are reported for a single pump laser source at 688 nm. We grew thulium-doped KGd(WO 4 ) 2 single crystals at several concentrations from 0.1% to 10%. We recorded a polarized optical absorption spectrum for the 3 F 2 + 3 F 3 energy levels of thulium at room temperature and low temperature (6 K). From the low temperature emission spectra we determined the splitting of the 3 H 6 ground state. The blue emissions are characterized as a function of the dopant concentration and temperature from 10 K to room temperature. To our knowledge, this is the first time that sequential two-photon excitation process (STEP) generated blue emissions in thulium-doped single crystals with a single excitation wavelength

Synthesis, crystal growth, optical, thermal, and mechanical properties of a nonlinear optical single crystal: ammonium sulfate hydrogen sulphamate (ASHS)

Science.gov (United States)

Sudhakar, K.; Nandhini, S.; Muniyappan, S.; Arumanayagam, T.; Vivek, P.; Murugakoothan, P.

2018-04-01

Ammonium sulfate hydrogen sulphamate (ASHS), an inorganic nonlinear optical crystal, was grown from the aqueous solution by slow evaporation solution growth technique. The single-crystal XRD confirms that the grown single crystal belongs to the orthorhombic system with the space group of Pna21. Powder XRD confirms the crystalline nature and the diffraction planes were indexed. Crystalline perfection of grown crystal was analysed by high-resolution X-ray diffraction rocking curve technique. UV-Vis-NIR studies revealed that ASHS crystal has optical transparency 65% and lower cut-off wavelength at 218 nm. The violet light emission of the crystal was identified by photoluminescence studies. The particle size-dependent second-harmonic generation efficiency for ASHS crystal was evaluated by Kurtz-Perry powder technique using Nd:YAG laser which established the existence of phase matching. Surface laser damage threshold value was evaluated using Nd:YAG laser. Optical homogeneity of the crystal was evaluated using modified channel spectrum method through birefringence study. Thermal analysis reveals that ASHS crystal is stable up to 213 °C. The mechanical behaviour of the ASHS crystal was analysed using Vickers microhardness study.

Beryllium, zinc and lead single crystals as a thermal neutron monochromators

Energy Technology Data Exchange (ETDEWEB)

Adib, M.; Habib, N. [Reactor Physics Department, NRC, Atomic Energy Authority, Cairo (Egypt); Bashter, I.I. [Physics Department, Faculty of Science, Zagazig University (Egypt); Morcos, H.N.; El-Mesiry, M.S. [Reactor Physics Department, NRC, Atomic Energy Authority, Cairo (Egypt); Mansy, M.S., E-mail: drmohamedmansy88@hotmail.com [Physics Department, Faculty of Science, Zagazig University (Egypt)

2015-03-15

Highlights: •Monochromatic features of Be, Zn and Pb single crystals. •Calculations of neutron reflectivity using a computer program MONO. •Optimum mosaic spread, thickness and cutting plane of single crystals. -- Abstract: The monochromatic features of Be, Zn and Pb single crystals are discussed in terms of orientation, mosaic spread, and thickness within the wavelength band from 0.04 up to 0.5 nm. A computer program MONO written in “FORTRAN-77”, has been adapted to carry out the required calculations. Calculations show that a 5 mm thick of beryllium (HCP structure) single crystal cut along its (0 0 2) plane having 0.6° FWHM are the optimum parameters when it is used as a monochromator with high reflected neutron intensity from a thermal neutron flux. Furthermore, at wavelengths shorter than 0.16 nm it is free from the accompanying higher order ones. Zinc (HCP structure) has the same parameters, with intensity much less than the latter. The same features are seen with lead (FCC structure) cut along its (3 1 1) plane with less reflectivity than the former. However, Pb (3 1 1) is more preferable than others at neutron wavelengths ⩽ 0.1 nm, since the glancing angle (θ ∼ 20°) is more suitable to carry out diffraction experiments. For a cold neutron flux, the first-order neutrons reflected from beryllium is free from the higher orders up to 0.36 nm. While for Zn single crystal is up to 0.5 nm.

Welding and Weldability of Directionally Solidified Single Crystal Nickel-Base Superalloys

Energy Technology Data Exchange (ETDEWEB)

Vitek, J M; David, S A; Reed, R W; Burke, M A; Fitzgerald, T J

1997-09-01

Nickel-base superalloys are used extensively in high-temperature service applications, and in particular, in components of turbine engines. To improve high-temperature creep properties, these alloys are often used in the directionally-solidified or single-crystal form. The objective of this CRADA project was to investigate the weldability of both experimental and commercial nickel-base superalloys in polycrystalline, directionally-solidified, and single-crystal forms.

Soluble salts addition modifies MgO hydration

International Nuclear Information System (INIS)

Santos, A.M.; Pandolfelli, V.C.; Salomao, R.

2012-01-01

Magnesium oxide (MgO) show great technological interest on refractories due to its high refractoriness, basic slag corrosion resistance and competitive cost. However, the hydration reaction of MgO produces magnesium hydroxide. This reaction generates a significant volumetric expansion that can lead to material breakdown inhibiting its use in refractory castables. This reaction can be affected by several factors such as magnesia source, purity, calcination temperature, pH, CaO/SiO 2 ratio and agitation speed. In the present work, soluble salts (CaCl 2 and MgCl 2 ) were used in MgO aqueous suspensions (caustic and sinter). The results were evaluated by means of techniques of degree of hydration (termogravimetric), Scanning electron microscopy, apparent volumetric expansion and x-ray Diffraction which showed that the degree of hydration was noticeably less to sinter aqueous and the expansive effects were less with the addition of CaCl 2 . (author)

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

International Nuclear Information System (INIS)

Zhuang, Zhi; Yoshimura, Hideyuki; Aizawa, Mamoru

2013-01-01

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

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.

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.

Crystal growth and luminescence properties of Pr-doped LuLiF4 single crystal

International Nuclear Information System (INIS)

Sugiyama, Makoto; Yanagida, Takayuki; Yokota, Yuui; Kurosawa, Shunsuke; Fujimoto, Yutaka; Yoshikawa, Akira

2013-01-01

0.1, 1, and 3% Pr (with respect to Lu) doped LuLiF 4 (Pr:LuLiF 4 ) single crystals were grown by the micro-pulling-down (μ-PD) method. Transparency of the grown crystals was higher than 70% in the visible wavelength region with some absorption bands due to Pr 3+ 4f-4f transitions. Intense absorption bands related with the Pr 3+ 4f-5d transitions were observed at 190 and 215 nm. In radioluminescence spectra, Pr 3+ 5d-4f emissions were observed at 220, 240, 340, and 405 nm. In the pulse height spectra recorded under 137 Cs γ-ray excitation, the Pr 3% doped sample showed the highest light yield of 2050 photons/MeV and the scintillation decay time of it exhibited 23 and 72 ns also excited by 137 Cs γ-ray. -- Highlights: ► 0.1, 1, and 3% Pr-doped LuLiF 4 single crystals were grown by the μ-PD method. ► Pr 3+ 5d-4f emission peaks appeared at 220, 240, 340, and 405 nm ► The Pr 3%:LuLiF 4 crystal showed the highest light yield of 2050 photons/MeV

Stacking fault tetrahedron induced plasticity in copper single crystal

Energy Technology Data Exchange (ETDEWEB)

Zhang, Liang, E-mail: lz592@uowmail.edu.au [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Lu, Cheng, E-mail: chenglu@uow.edu.au [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Tieu, Kiet; Su, Lihong; Zhao, Xing [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Pei, Linqing [Department of Mechanical Engineering, Chongqing University, Chongqing 400044 (China)

2017-01-05

Stacking fault tetrahedron (SFT) is the most common type of vacancy clustered defects in fcc metals and alloys, and can play an important role in the mechanical properties of metallic materials. In this study, molecular dynamics (MD) simulations were carried out to investigate the incipience of plasticity and the underlying atomic mechanisms in copper single crystals with SFT. Different deformation mechanisms of SFT were reported due to the crystal orientations and loading directions (compression and tension). The results showed that the incipient plasticity in crystals with SFT resulted from the heterogeneous dislocation nucleation from SFT, so the stress required for plastic deformation was less than that needed for perfect single crystals. Three crystal orientations ([1 0 0], [1 1 0] and [1 1 1]) were specified in this study because they can represent most of the typical deformation mechanisms of SFT. MD simulations revealed that the structural transformation of SFT was frequent under the applied loading; a metastable SFT structure and the collapse of SFT were usually observed. The structural transformation resulted in a different reduction of yield stress in compression and tension, and also caused a decreased or reversed compression/tension asymmetry. Compressive stress can result in the unfaulting of Frank loop in some crystal orientations. According to the elastic theory of dislocation, the process of unfaulting was closely related to the size of the dislocation loop and the stacking fault energy.

Preparation and characterization of single-crystal multiferroic nanofiber composites

Energy Technology Data Exchange (ETDEWEB)

Ren, Zhaohui; Xiao, Zhen; Yin, Simin; Mai, Jiangquan; Liu, Zhenya; Xu, Gang; Li, Xiang; Shen, Ge [State Key Lab of Silicon Materials, Department of Material Science and Engineering, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China); Han, Gaorong, E-mail: hgr@zju.edu.cn [State Key Lab of Silicon Materials, Department of Material Science and Engineering, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China)

2013-03-05

Graphical abstract: One-dimensional single-crystal multiferroic composites composed of PbTiO{sub 3} nanofiber-CoFe{sub 2}O{sub 4} nanodot have been prepared for the first time by a facile in situ solid state sintering method. The composites demonstrate ferroelectricity and ferromagnetism as well as strong coupling between them. Highlights: ► 1D single-crystal multiferroic PTO-CFO was prepared via in situ solid state sintering method. ► A simple epitaxial growth relation has been found between the PTO–CFO composites. ► The composites reveal ferroelectricity and ferromagnetism as well as coupling between them. -- Abstract: One-dimensional single-crystal multiferroic composites consisting of PbTiO{sub 3} (PTO) nanofiber-CoFe{sub 2}O{sub 4} (CFO) nanodot were prepared using an in situ solid state sintering method, where pre-perovskite PTO nanofibers and CFO nanodots were used as precursors. Structural analyses by using transmission electron microscopy, scanning electron microscopy and X-ray diffraction determined a epitaxial growth relation between the PTO nanofiber and the CFO nanodot. Ferromagnetism and ferroelectricity of the nanofiber composites were investigated by using vibarting sample magnetometer (VSM) and piezoresponse force microscopy (PFM)

Mangotoxin production of Pseudomonas syringae pv. syringae is regulated by MgoA.

Science.gov (United States)

Carrión, Víctor J; van der Voort, Menno; Arrebola, Eva; Gutiérrez-Barranquero, José A; de Vicente, Antonio; Raaijmakers, Jos M; Cazorla, Francisco M

2014-02-21

The antimetabolite mangotoxin is a key factor in virulence of Pseudomonas syringae pv. syringae strains which cause apical necrosis of mango trees. Previous studies showed that mangotoxin biosynthesis is governed by the mbo operon. Random mutagenesis led to the identification of two other gene clusters that affect mangotoxin biosynthesis. These are the gacS/gacA genes and mgo operon which harbors the four genes mgoBCAD. The current study shows that disruption of the nonribosomal peptide synthetase (NRPS) gene mgoA resulted in loss of mangotoxin production and reduced virulence on tomato leaves. Transcriptional analyses by qPCR and promoter reporter fusions revealed that mbo expression is regulated by both gacS/gacA and mgo genes. Also, expression of the mgo operon was shown to be regulated by gacS/gacA. Heterologous expression under the native promoter of the mbo operon resulted in mangotoxin production in non-producing P. syringae strains, but not in other Pseudomonas species. Also introduction of the mbo and mgo operons in nonproducing P. protegens Pf-5 did not confer mangotoxin production but did enhance transcription of the mbo promoter. From the data obtained in this study, we conclude that both mbo and mgo operons are under the control of the gacS/gacA two-component system and that the MgoA product acts as a positive regulator of mangotoxin biosynthesis.

Welding and joining of single crystals of BCC refractory metals

International Nuclear Information System (INIS)

Hiraoka, Yutaka; Fujii, Tadayuki

1989-01-01

Welding and joining is one of key technologies for the wider utilizations of a material. In the present work, the applicability of welding and joining for a single crystal of BCC refractory metal was investigated. Electron-beam welding and tungsten-inert-gas welding by a melt-run technique, and high-temperature brazing by using brazing metals such as Mo-40%Ru alloy, vanadium or platinum were conducted for molybdenum single crystal which had been prepared by means of secondary recrystallization. 12 refs.,12 figs., 2 tabs. (Author)

Elastic neutron diffraction study of transforming and non-transforming single crystal ZrV2

International Nuclear Information System (INIS)

Bostock, J.; Wong, M.; MacVicar, M.L.A.; Levinson, M.

1980-01-01

The mosaic spread of single crystal ZrV 2 is unusually narrow, approx. 1' from room temperature to 130K. For non-transforming perfect single crystal the mosaic gradually increases to approx. 1.86' at 4.2K; for transforming, twinned single crystal the room temperature mosaic is maintained to 110K, then increases to 2.76' at 94K when the crystal transforms to a mixed cubic (30%) and rhombohedral state (70%). The onset of the electronic instability (approx. 100K) is accompanied by an increase in diffuse scattering background which, for the twinned crystal, peaks at the structural transformation. The electronic instability coupled to the localized lattice stress appears to be the driving mechanism for the transformation

Self-reporting inhibitors: single crystallization process to get two optically pure enantiomers.

Science.gov (United States)

Wan, Xinhua; Ye, Xichong; Cui, Jiaxi; Li, Bowen; Li, Na; Zhang, Jie

2018-05-22

Collection of two optically pure enantiomers in a single crystallization process can significantly increase the chiral separation efficiency but it's hard to realize nowadays. Herein we describe, for the first time, a self-reporting strategy for visualizing the crystallization process by a kind of dyed self-assembled inhibitors made from the copolymers with tri(ethylene glycol)-grafting polymethylsiloxane as main chains and poly(N6-methacryloyl-L-lysine) as side chains. When applied with seeds together for the fractional crystallization of conglomerates, the inhibitors can label the formation of the secondary crystals and guide us to completely separate the crystallization process of two enantiomers with colorless crystals as the first product and red crystals as the secondary product. This method leads to high optical purity of D/L-Asn·H2O (99.9 ee% for D-crystals and 99.5 ee% for L-crystals) in a single crystallization process. Moreover, it requires low feeding amount of additives and shows excellent recyclability. We foresee its great potential in developing novel chiral separation methods that can be used in different scales. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single crystal magnetisation of UFe10Mo2

International Nuclear Information System (INIS)

Estrela, P.; Godinho, M.; Spirlet, J.C.

1997-01-01

Magnetisation measurements have been performed for different directions on aligned UFe 10 Mo 2 single crystals. The results confirm a basal plane anisotropy and suggest an important magnetic contribution from the uranium sublattice. (orig.)

Solid-melt interface structure and growth of Cu alloy single crystals

International Nuclear Information System (INIS)

Tomimitsu, Hiroshi; Kamada, Kohji.

1983-01-01

Crystal-melt interface behavior during the growth of Cu-base solid solutions by the Bridgman method is discussed on the basis of experimental evidence obtained by neutron diffraction topography. Advantages of neutron diffraction topography for the characterization of large single crystals, such as dealt with in this paper, are emphasized. Evidence was odserved of extremely regular crystal growth along directions, irrespective of the macroscopic growth direction. This contrasts with the previously believed (110) normal growth which is a conclusion of growth theory based on molecular kinetics at the solid-melt interface. In consequence, we believe that the kinetics at the interface is a minor factor in the meltgrowth of metal single crystals. Revised melt-growth theory should include both the growth and the formation of the regular structure as evidenced by neutron diffraction topography. (author)

Patterning solution-processed organic single-crystal transistors with high device performance

Directory of Open Access Journals (Sweden)

Yun Li

2011-06-01

Full Text Available We report on the patterning of organic single-crystal transistors with high device performance fabricated via a solution process under ambient conditions. The semiconductor was patterned on substrates via surface selective deposition. Subsequently, solvent-vapor annealing was performed to reorganize the semiconductor into single crystals. The transistors exhibited field-effect mobility (μFET of up to 3.5 cm2/V s. Good reliability under bias-stress conditions indicates low density of intrinsic defects in crystals and low density of traps at the active interfaces. Furthermore, the Y function method clearly suggests that the variation of μFET of organic crystal transistors was caused by contact resistance. Further improvement of the device with higher μFET with smaller variation can be expected when lower and more uniform contact resistance is achieved.

Lattice effects in YVO3 single crystal

NARCIS (Netherlands)

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

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 =

Dynamic Actuation of Single-Crystal Diamond Nanobeams

OpenAIRE

Sohn, Young-Ik; Burek, Michael J.; Kara, Vural; Kearns, Ryan; Lončar, Marko

2014-01-01

We show the dielectrophoretic actuation of single-crystal diamond nanomechanical devices. Gradient radio-frequency electromagnetic forces are used to achieve actuation of both cantilever and doubly clamped beam structures, with operation frequencies ranging from a few MHz to ~50MHz. Frequency tuning and parametric actuation are also studied.

Method for manufacturing a single crystal nanowire

NARCIS (Netherlands)

van den Berg, Albert; Bomer, Johan G.; Carlen, Edwin; Chen, S.; Kraaijenhagen, Roderik Adriaan; Pinedo, Herbert Michael

2013-01-01

A method for manufacturing a single crystal nano-structure is provided comprising the steps of providing a device layer with a 100 structure on a substrate; providing a stress layer onto the device layer; patterning the stress layer along the 110 direction of the device layer; selectively removing

Method for manufacturing a single crystal nanowire

NARCIS (Netherlands)

van den Berg, Albert; Bomer, Johan G.; Carlen, Edwin; Chen, S.; Kraaijenhagen, R.A.; Pinedo, Herbert Michael

2010-01-01

A method for manufacturing a single crystal nano-structure is provided comprising the steps of providing a device layer with a 100 structure on a substrate; providing a stress layer onto the device layer; patterning the stress layer along the 110 direction of the device layer; selectively removing

Growth and characterization of air annealing Tb-doped YAG:Ce single crystal for white-light-emitting diode

International Nuclear Information System (INIS)

Gong, Maogao; Xiang, Weidong; Liang, Xiaojuan; Zhong, Jiasong; Chen, Daqin; Huang, Jun; Gu, Guorui; Yang, Cheng; Xiang, Run

2015-01-01

Highlights: • We report preparation of transparent Ce,Tb:YAG single crystal by Czochralski method. • The effect of annealing on Ce,Tb:YAG single crystal had been investigated. • The Ce,Tb:YAG single crystal after annealing exhibited better optical performance. • The Ce,Tb:YAG single crystal could be used as an ideal candidate for WLED. - Abstract: We report the preparation of transparent Ce and Tb co-doped Y 3 Al 5 O 12 single crystal by the Czochralski method. The characterization of the resulting single crystal was accomplished by using X-ray powder diffractometer, scanning electron microscopy and energy dispersive X-ray spectroscopy. Absorption peak of the single crystal at about 460 nm has been obtained from ultraviolet–visible absorption spectrometer and their intensity is changed with different annealing condition. Its optical properties also have been investigated using fluorescence spectrometer. What’s more, its photoelectric parameters were studied by LED fast spectrometer. The constructed single crystal based white-light-emitting diode exhibits a high luminous efficiency of 140.89 lm/W, and a correlated color temperature of 4176 K as well as a color rendering index of 56.7, which reveal the prominent feasibility of the present single crystal material in white-light-emitting diode application

Growth and characterization of air annealing Tb-doped YAG:Ce single crystal for white-light-emitting diode

Energy Technology Data Exchange (ETDEWEB)

Gong, Maogao [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China); Xiang, Weidong, E-mail: xiangweidong001@126.com [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China); Liang, Xiaojuan [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China); Zhong, Jiasong; Chen, Daqin [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Huang, Jun; Gu, Guorui; Yang, Cheng; Xiang, Run [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China)

2015-08-05

Highlights: • We report preparation of transparent Ce,Tb:YAG single crystal by Czochralski method. • The effect of annealing on Ce,Tb:YAG single crystal had been investigated. • The Ce,Tb:YAG single crystal after annealing exhibited better optical performance. • The Ce,Tb:YAG single crystal could be used as an ideal candidate for WLED. - Abstract: We report the preparation of transparent Ce and Tb co-doped Y{sub 3}Al{sub 5}O{sub 12} single crystal by the Czochralski method. The characterization of the resulting single crystal was accomplished by using X-ray powder diffractometer, scanning electron microscopy and energy dispersive X-ray spectroscopy. Absorption peak of the single crystal at about 460 nm has been obtained from ultraviolet–visible absorption spectrometer and their intensity is changed with different annealing condition. Its optical properties also have been investigated using fluorescence spectrometer. What’s more, its photoelectric parameters were studied by LED fast spectrometer. The constructed single crystal based white-light-emitting diode exhibits a high luminous efficiency of 140.89 lm/W, and a correlated color temperature of 4176 K as well as a color rendering index of 56.7, which reveal the prominent feasibility of the present single crystal material in white-light-emitting diode application.

Positronium hydride defects in thermochemically reduced alkaline-Earth oxides

International Nuclear Information System (INIS)

Monge, M.A.; Pareja, R.; Gonzalez, R.; Chen, Y.

1997-01-01

Thermochemical reduction of both hydrogen-doped MgO and CaO single crystals results in large concentrations of hydride (H - ) ions. In MgO crystals, positron lifetime and Doppler broadening experiments show that positrons are trapped at H - centers forming positronium hydride molecules [e + - H - ]. A value of 640 ps is obtained for the lifetime of the PsH states located in an anion vacancy In MgO positrons are also trapped at H 2- sites at low temperatures. The H 2- ions were induced in the crystals by blue light illumination. The formation of PsH states in CaO could not be conclusively established. (orig.)

Structural and optical properties of WTe2 single crystals synthesized by DVT technique

Science.gov (United States)

Dixit, Vijay; Vyas, Chirag; Pathak, V. M.; Soalanki, G. K.; Patel, K. D.

2018-05-01

Layered transition metal di-chalcogenide (LTMDCs) crystals have attracted much attention due to their potential in optoelectronic device applications recently due to realization of their monolayer based structures. In the present investigation we report growth of WTe2 single crystals by direct vapor transport (DVT) technique. These crystals are then characterized by energy dispersive analysis of x-rays (EDAX) to study stoichiometric composition after growth. The structural properties are studied by x-ray diffraction (XRD) and selected area electron diffraction (SAED) is used to confirm orthorhombic structure of grown WTe2 crystal. Surface morphological properties of the crystals are also studied by scanning electron microscope (SEM). The optical properties of the grown crystals are studied by UV-Visible spectroscopy which gives direct band gap of 1.44 eV for grown WTe2 single crystals.

Surface structure of MgO underlayer with Ti diffusion for (002 oriented L10 FePt-based heat assisted magnetic recording media

Directory of Open Access Journals (Sweden)

Sintaro Hinata

2018-05-01

Full Text Available Surface morphology of the MgO layer and magnetic properties of FePt-C layer deposited on the MgO were investigated for the FePt-based heat assisted magnetic recording media. Stacking structure of the underlayer for the FePt-C layer was MgO (0-5 nm/Cr80Mn20 (0-30 nm/Cr50Ti50 (0-50 nm/glass sub.. Surface observation result for the MgO film by using an atomic force microscope revealed the existence of nodules with a height of about 2 nm and a network-like convex structure with a height difference of about sub nm (boundary wall, BW on the MgO crystal grain boundary. Density of the nodules largely depends on the surface roughness of the CrTi layer, RaCrTi and it is suppressed from 10 to 2/0.5 μm2 by reducing RaCrTi from 420 to 260 pm. Height of the BW depends on thickness of the MgO layer, tMgO and it can be suppressed by reducing tMgO to less than 4 nm. From the cross-sectional energy dispersive x-ray mapping, it is clarified that the BW is formed by atomic diffusion of Ti atoms from CrTi layer due to the substrate heating process, and a compound consists of Mg, Ti and O atoms. This BW can be used as a template to magnetically isolate the FePt column in the FePt-based granular film, such as FePt-SiO2, if the size of the BW is reduced to less than 10 nm. M-H loop of the FePt-C granular film deposited on the underlayer showed that the nodule and BW induce oxidation of the FePt grains, and reduction of intergranular exchange coupling.

Surface structure of MgO underlayer with Ti diffusion for (002) oriented L10 FePt-based heat assisted magnetic recording media

Science.gov (United States)

Hinata, Sintaro; Jo, Shin; Saito, Shin

2018-05-01

Surface morphology of the MgO layer and magnetic properties of FePt-C layer deposited on the MgO were investigated for the FePt-based heat assisted magnetic recording media. Stacking structure of the underlayer for the FePt-C layer was MgO (0-5 nm)/Cr80Mn20 (0-30 nm)/Cr50Ti50 (0-50 nm)/glass sub.. Surface observation result for the MgO film by using an atomic force microscope revealed the existence of nodules with a height of about 2 nm and a network-like convex structure with a height difference of about sub nm (boundary wall, BW) on the MgO crystal grain boundary. Density of the nodules largely depends on the surface roughness of the CrTi layer, RaCrTi and it is suppressed from 10 to 2/0.5 μm2 by reducing RaCrTi from 420 to 260 pm. Height of the BW depends on thickness of the MgO layer, tMgO and it can be suppressed by reducing tMgO to less than 4 nm. From the cross-sectional energy dispersive x-ray mapping, it is clarified that the BW is formed by atomic diffusion of Ti atoms from CrTi layer due to the substrate heating process, and a compound consists of Mg, Ti and O atoms. This BW can be used as a template to magnetically isolate the FePt column in the FePt-based granular film, such as FePt-SiO2, if the size of the BW is reduced to less than 10 nm. M-H loop of the FePt-C granular film deposited on the underlayer showed that the nodule and BW induce oxidation of the FePt grains, and reduction of intergranular exchange coupling.

Single-crystal neutron diffraction at the Australian Replacement Research Reactor

International Nuclear Information System (INIS)

Klooster, W.T.

2001-01-01

The purpose of the workshop was to: identify the future needs and opportunities for single-crystal neutron diffraction, and specify instrument requirements. important number of experiments. The conclusion of the workshop deliberation was that Australia has a diverse community of users of single-crystal neutron diffraction. A (quasi)-Laue image-plate diffractometer allows the fastest throughput by far, but would exclude an important number of experiments. Most of these could be covered by the additional possibility to locate the image-plate detector on a monochromatic beam. Therefore it was recommend both a white thermal beam and a monochromatic beam (λ= 1 to 2.4 Angstroms) for an image-plate detector. At little additional cost the existing 2TanA instrument could be located semi-permanently on the same monochromatic beam, thus offering three quite different types of single-crystal instruments. Small improvements could be made to the 2TanA instrument to cater for the remaining experiments not suited to an image-plate diffractometer: exchange of the Eulerian cradle for an automated tilt goniometer for extremely bulky sample environment (cryomagnets, large pressure cells), optional larger area detector, analyser crystal. It was recommended that an Instrument Advisory Team will be assembled, and will help in specifying, designing and commissioning the instrument

Growth, structural and magnetic characterization of Al-substituted barium hexaferrite single crystals

International Nuclear Information System (INIS)

Vinnik, D.A.; Zherebtsov, D.A.; Mashkovtseva, L.S.; Nemrava, S.; Bischoff, M.; Perov, N.S.; Semisalova, A.S.; Krivtsov, I.V.; Isaenko, L.I.; Mikhailov, G.G.; Niewa, R.

2014-01-01

Highlights: • Growth of large Al-substituted crystals BaFe 12−x Al x O 19. • Al-content controllable by flux composition. • Crystallographic site preference of Al unraveled. • Magnetic characterization depending on Al-content. - Abstract: Large single crystals of aluminum-substituted M-type barium hexaferrite BaFe 12−x Al x O 19 were obtained from carbonate flux. The Al content in the crystals can be controlled via the Al content of the flux up to x = 1.1 according to single crystal X-ray structure refinements. Al shows a distinct preference to substitute Fe on crystallographic sites with high coordination numbers by oxygen atoms, whereas no significant amounts of Al can be found on a tetrahedrally coordinated site. An increasing amount of the aluminum dopant results in a monotonous reduction of the Curie temperature from 440 to 415 °C and the saturation magnetization at room temperature from 68 to 57 emu/g for single crystal and from 61 to 53 emu/g for powder samples

Precipitation of thin-film organic single crystals by a novel crystal growth method using electrospray and ionic liquid film

Science.gov (United States)

Ueda, Hiroyuki; Takeuchi, Keita; Kikuchi, Akihiko

2018-04-01

We report an organic single crystal growth technique, which uses a nonvolatile liquid thin film as a crystal growth field and supplies fine droplets containing solute from the surface of the liquid thin film uniformly and continuously by electrospray deposition. Here, we investigated the relationships between the solute concentration of the supplied solution and the morphology and size of precipitated crystals for four types of fluorescent organic low molecule material [tris(8-hydroxyquinoline)aluminum (Alq3), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), N,N‧-bis(3-methylphenyl)-N,N‧-diphenylbenzidine (TPD), and N,N-bis(naphthalene-1-yl)-N,N-diphenyl-benzidine (NPB)] using an ionic liquid as the nonvolatile liquid. As the concentration of the supplied solution decreased, the morphology of precipitated crystals changed from dendritic or leaf shape to platelike one. At the solution concentration of 0.1 mg/ml, relatively large platelike single crystals with a diagonal length of over 100 µm were obtained for all types of material. In the experiment using ionic liquid and dioctyl sebacate as nonvolatile liquids, it was confirmed that there is a clear positive correlation between the maximum volume of the precipitated single crystal and the solubility of solute under the same solution supply conditions.

Single-crystal diffraction instrument TriCS at SINQ

Science.gov (United States)

Schefer, J.; Könnecke, M.; Murasik, A.; Czopnik, A.; Strässle, Th; Keller, P.; Schlumpf, N.

2000-03-01

The single-crystal diffractometer TriCS at the Swiss Continuous Spallation Source (SINQ) is presently in the commissioning phase. A two-dimensional wire detector produced by EMBL was delivered in March 1999. The instrument is presently tested with a single detector. First measurements on magnetic structures have been performed. The instrument is remotely controlled using JAVA-based software and a UNIX DEC-α host computer.

Fergusonite-type CeNbO{sub 4+δ}: Single crystal growth, symmetry revision and conductivity

Energy Technology Data Exchange (ETDEWEB)

Bayliss, Ryan D. [Department of Materials, Imperial College London, Prince Consort Road, London, SW7 2BP (United Kingdom); Pramana, Stevin S.; An, Tao; Wei, Fengxia; Kloc, Christian L. [School of Materials Science and Engineering, 50 Nanyang Avenue, Nanyang Technological University, 639798 (Singapore); White, Andrew J.P. [Chemical Crystallography Laboratory, Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ (United Kingdom); Skinner, Stephen J. [Department of Materials, Imperial College London, Prince Consort Road, London, SW7 2BP (United Kingdom); White, Timothy J. [School of Materials Science and Engineering, 50 Nanyang Avenue, Nanyang Technological University, 639798 (Singapore); Baikie, Tom, E-mail: tbaikie@ntu.edu.sg [School of Materials Science and Engineering, 50 Nanyang Avenue, Nanyang Technological University, 639798 (Singapore)

2013-08-15

Large fergusonite-type (ABO{sub 4}, A=Ce, B=Nb) oxide crystals, a prototype electrolyte composition for solid oxide fuel cells (SOFC), were prepared for the first time in a floating zone mirror furnace under air or argon atmospheres. While CeNbO{sub 4} grown in air contained CeNbO{sub 4.08} as a minor impurity that compromised structural analysis, the argon atmosphere yielded a single phase crystal of monoclinic CeNbO{sub 4}, as confirmed by selected area electron diffraction, powder and single crystal X-ray diffraction. The structure was determined in the standard space group setting C12/c1 (No. 15), rather than the commonly adopted I12/a1. AC impedance spectroscopy conducted under argon found that stoichiometric CeNbO{sub 4} single crystals showed lower conductivity compared to CeNbO{sub 4+δ} confirming interstitial oxygen can penetrate through fergusonite and is responsible for the higher conductivity associated with these oxides. - Graphical abstract: Large fergusonite-type CeNbO{sub 4} crystals were prepared for the first time in a floating zone mirror furnace. Crystal growth in an argon atmosphere yielded a single phase monoclinic CeNbO4, as confirmed by selected area electron diffraction, powder and single crystal X-ray diffraction. The structure was determined in the standard space group setting C12/c1 (No. 15), rather than the commonly adopted I12/a1. AC impedance spectroscopy found CeNbO{sub 4} single crystals showed lower conductivity compared to CeNbO{sub 4+δ} confirming interstitial oxygen can penetrate through fergusonite and is responsible for the higher conductivity associated with these oxides. Highlights: • Preparation of single crystals of CeNbO{sub 4} using a floating zone mirror furnace. • Correction to the crystal symmetry of the monoclinic form of CeNbO{sub 4}. • Report the conductivity of a single crystal of CeNbO{sub 4}.

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

KAUST Repository

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

2015-01-01

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

Synthesis and Single Crystal X-Ray Structure Determination of 3,3',5 ...

African Journals Online (AJOL)

Single crystal structure determination at 100 K revealed needle-like crystals in an orthorhombic crystal system. The asymmetric unit of the cell consists of an isolated chloride ion, one half of a tetrahedral [MnCl4]2- anion, a [H2Me4bpz]2+ dication and one half of a molecule of water. Keywords: Crystal Engineering, Hydrogen ...

Characterisation of irradiation-induced defects in ZnO single crystals

International Nuclear Information System (INIS)

Prochazka, I; Cizek, J; Lukac, F; Melikhova, O; Valenta, J; Havranek, V; Anwand, W; Skuratov, V A; Strukova, T S

2016-01-01

Positron annihilation spectroscopy (PAS) combined with optical methods was employed for characterisation of defects in the hydrothermally grown ZnO single crystals irradiated by 167 MeV Xe 26+ ions to fluences ranged from 3×10 12 to 1×10 14 cm -2 . The positron lifetime (LT), Doppler broadening as well as slow-positron implantation spectroscopy (SPIS) techniques were involved. The ab-initio theoretical calculations were utilised for interpretation of LT results. The optical transmission and photoluminescence measurements were conducted, too. The virgin ZnO crystal exhibited a single component LT spectrum with a lifetime of 182 ps which is attributed to saturated positron trapping in Zn vacancies associated with hydrogen atoms unintentionally introduced into the crystal during the crystal growth. The Xe ion irradiated ZnO crystals have shown an additional component with a longer lifetime of ≈ 360 ps which comes from irradiation-induced larger defects equivalent in size to clusters of ≈10 to 12 vacancies. The concentrations of these clusters were estimated on the basis of combined LT and SPIS data. The PAS data were correlated with irradiation induced changes seen in the optical spectroscopy experiments. (paper)

Characterisation of irradiation-induced defects in ZnO single crystals

Science.gov (United States)

Prochazka, I.; Cizek, J.; Lukac, F.; Melikhova, O.; Valenta, J.; Havranek, V.; Anwand, W.; Skuratov, V. A.; Strukova, T. S.

2016-01-01

Positron annihilation spectroscopy (PAS) combined with optical methods was employed for characterisation of defects in the hydrothermally grown ZnO single crystals irradiated by 167 MeV Xe26+ ions to fluences ranged from 3×1012 to 1×1014 cm-2. The positron lifetime (LT), Doppler broadening as well as slow-positron implantation spectroscopy (SPIS) techniques were involved. The ab-initio theoretical calculations were utilised for interpretation of LT results. The optical transmission and photoluminescence measurements were conducted, too. The virgin ZnO crystal exhibited a single component LT spectrum with a lifetime of 182 ps which is attributed to saturated positron trapping in Zn vacancies associated with hydrogen atoms unintentionally introduced into the crystal during the crystal growth. The Xe ion irradiated ZnO crystals have shown an additional component with a longer lifetime of ≈ 360 ps which comes from irradiation-induced larger defects equivalent in size to clusters of ≈10 to 12 vacancies. The concentrations of these clusters were estimated on the basis of combined LT and SPIS data. The PAS data were correlated with irradiation induced changes seen in the optical spectroscopy experiments.

Crystal growth and mechanical hardness of In{sub 2}Se{sub 2.7}Sb{sub 0.3} single crystal

Energy Technology Data Exchange (ETDEWEB)

Patel, Piyush, E-mail: piyush-patel130@yahoo.com; Vyas, S. M., E-mail: s-m-vyas-gu@hotmail.com; Patel, Vimal; Pavagadhi, Himanshu [Department of Physics, School of Science, Gujarat University, Ahmedabad, Gujarat, India-380009 (India); Solanki, Mitesh [panditdindayal Petroleum University, Gandhinagar. Gujarat (India); Jani, Maunik P. [BITS Edu Campus, Varnama, Vadodara, Gujarat (India)

2015-08-28

The III-VI compound semiconductors is important for the fabrication of ionizing radiation detectors, solid-state electrodes, and photosensitive heterostructures, solar cell and ionic batteries. In this paper, In{sub 2}Se{sub 2.7} Sb{sub 0.3} single crystals were grown by the Bridgman method with temperature gradient of 60 °C/cm and the growth velocity 0.5cm/hr. The as-grown crystals were examined under the optical microscope for surface study, a various growth features observed on top free surface of the single crystal which is predominant of layers growth mechanism. The lattice parameters of as-grown crystal was determined by the XRD analysis. A Vickers’ projection microscope were used for the study of microhardness on the as-cleaved, cold-worked and annealed samples of the crystals, the results were discussed, and reported in detail.

Neutron forward diffraction by single crystal prisms

Indian Academy of Sciences (India)

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 ...

Anisotropic surface hole-transport property of triphenylamine-derivative single crystal prepared by solution method

Energy Technology Data Exchange (ETDEWEB)

Umeda, Minoru, E-mail: mumeda@vos.nagaokaut.ac.jp [Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Katagiri, Mitsuhiko; Shironita, Sayoko [Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Nagayama, Norio [Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Ricoh Company, Ltd., Nishisawada, Numazu, Shizuoka 410-0007 (Japan)

2016-12-01

Highlights: • A hole transport molecule was investigated based on its electrochemical redox characteristics. • The solubility and supersolubility curves of the molecule were measured in order to prepare a large crystal. • The polarization micrograph and XRD results revealed that a single crystal was obtained. • An anisotropic surface conduction, in which the long-axis direction exceeds that of the amorphous layer, was observed. • The anisotropic surface conduction was well explained by the molecular stacked structure. - Abstract: 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.

Plastic deformation of Ni3Nb single crystals

International Nuclear Information System (INIS)

Hagihara, Kouji; Nakano, Takayoshi; Umakoshi, Yukichi

1999-01-01

Temperature dependence of yield stress and operative slip system in Ni 3 Nb single crystals with the D0 a structure was investigated in comparison with that in an analogous L1 2 structure. Compression tests were performed at temperatures between 20 C and 1,200 C for specimens with loading axes perpendicular to (110), (331) and (270). (010)[100] slip was operative for three orientations, while (010)[001] slip for (331) and [211] twin for (270) orientations were observed, depending on deformation temperature. The critical resolved shear stress (CRSS) for the (010)[100] slip anomaly increased with increasing temperature showing a maximum peak between 400 C and 800 C depending on crystal orientation. The CRSS showed orientation dependence and no significant strain rate dependence in the temperature range for anomalous strengthening. The [100] dislocations with a screw character were aligned on the straight when the anomalous strengthening occurred. The anomalous strengthening mechanism for (010)[100] slip in Ni 3 Nb single crystals is discussed on the basis of a cross slip model which has been widely accepted for some L1 2 -type compounds

Evaluation of single crystal coefficients from mechanical and x-ray elastic constants of the polycrystal

International Nuclear Information System (INIS)

Hauk, V.; Kockelmann, H.

1979-01-01

Methods of calculation are developed for determination of single crystal elastic compliance or stiffness constants of cubic and hexagonal materials from mechanical and X-ray elastic constants of polycrystals. The calculations are applied to pure, cubic iron and hexagonal WC. There are no single crystal constants in the literature for WC, because no single crystals suitable for measurement are available. (orig.) [de

Ensembles of indium phosphide nanowires: physical properties and functional devices integrated on non-single crystal platforms

International Nuclear Information System (INIS)

Kobayashi, Nobuhiko P.; Lohn, Andrew; Onishi, Takehiro; Mathai, Sagi; Li, Xuema; Straznicky, Joseph; Wang, Shih-Yuan; Williams, R.S.; Logeeswaran, V.J.; Islam, M.S.

2009-01-01

A new route to grow an ensemble of indium phosphide single-crystal semiconductor nanowires is described. Unlike conventional epitaxial growth of single-crystal semiconductor films, the proposed route for growing semiconductor nanowires does not require a single-crystal semiconductor substrate. In the proposed route, instead of using single-crystal semiconductor substrates that are characterized by their long-range atomic ordering, a template layer that possesses short-range atomic ordering prepared on a non-single-crystal substrate is employed. On the template layer, epitaxial information associated with its short-range atomic ordering is available within an area that is comparable to that of a nanowire root. Thus the template layer locally provides epitaxial information required for the growth of semiconductor nanowires. In the particular demonstration described in this paper, hydrogenated silicon was used as a template layer for epitaxial growth of indium phosphide nanowires. The indium phosphide nanowires grown on the hydrogenerated silicon template layer were found to be single crystal and optically active. Simple photoconductors and pin-diodes were fabricated and tested with the view towards various optoelectronic device applications where group III-V compound semiconductors are functionally integrated onto non-single-crystal platforms. (orig.)

Ensembles of indium phosphide nanowires: physical properties and functional devices integrated on non-single crystal platforms

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Nobuhiko P.; Lohn, Andrew; Onishi, Takehiro [University of California, Santa Cruz (United States). Baskin School of Engineering; NASA Ames Research Center, Nanostructured Energy Conversion Technology and Research (NECTAR), Advanced Studies Laboratories, Univ. of California Santa Cruz, Moffett Field, CA (United States); Mathai, Sagi; Li, Xuema; Straznicky, Joseph; Wang, Shih-Yuan; Williams, R.S. [Hewlett-Packard Laboratories, Information and Quantum Systems Laboratory, Palo Alto, CA (United States); Logeeswaran, V.J.; Islam, M.S. [University of California Davis, Electrical and Computer Engineering, Davis, CA (United States)

2009-06-15

A new route to grow an ensemble of indium phosphide single-crystal semiconductor nanowires is described. Unlike conventional epitaxial growth of single-crystal semiconductor films, the proposed route for growing semiconductor nanowires does not require a single-crystal semiconductor substrate. In the proposed route, instead of using single-crystal semiconductor substrates that are characterized by their long-range atomic ordering, a template layer that possesses short-range atomic ordering prepared on a non-single-crystal substrate is employed. On the template layer, epitaxial information associated with its short-range atomic ordering is available within an area that is comparable to that of a nanowire root. Thus the template layer locally provides epitaxial information required for the growth of semiconductor nanowires. In the particular demonstration described in this paper, hydrogenated silicon was used as a template layer for epitaxial growth of indium phosphide nanowires. The indium phosphide nanowires grown on the hydrogenerated silicon template layer were found to be single crystal and optically active. Simple photoconductors and pin-diodes were fabricated and tested with the view towards various optoelectronic device applications where group III-V compound semiconductors are functionally integrated onto non-single-crystal platforms. (orig.)

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.

Optical properties of GaS:Ho3+ and GaS:Tm3+ single crystals

International Nuclear Information System (INIS)

Jin, Moon-Seog; Kim, Chang-Dae; Kim, Wha-Tek

2004-01-01

GaS:Ho 3+ and GaS:Tm 3+ single crystals were grown by using the chemical transport reaction method. We measured the optical absorption, the infra-red absorption, and the photoluminescence spectra of the single crystals. The direct and the indirect energy band gaps of the single crystals at 13 K were identified. Infra-red absorption peaks at 6 K appeared in the single crystals. Broad emission bands at 6 K were observed at 464 nm and 580 nm for GaS:Ho 3+ and 462 nm and 581 nm for GaS:Tm 3+ . These broad emission bands were identified as originating from donor-acceptor pair recombinations. Sharp emission peak groups were observed near 435 nm, 495 nm, and 660 nm for GaS:Ho 3+ and near 672 nm for GaS:Tm 3+ . These sharp emission peak groups were identified as being due to the electron transitions between the energy levels of Ho 3+ and Tm 3+ . Especially, white photoluminescence was obtained in the GaS:Ho 3+ single crystal.

Mechanical and optical nanodevices in single-crystal quartz

Science.gov (United States)

Sohn, Young-Ik; Miller, Rachel; Venkataraman, Vivek; Lončar, Marko

2017-12-01

Single-crystal α-quartz, one of the most widely used piezoelectric materials, has enabled a wide range of timing applications. Owing to the fact that an integrated thin-film based quartz platform is not available, most of these applications rely on macroscopic, bulk crystal-based devices. Here, we show that the Faraday cage angled-etching technique can be used to realize nanoscale electromechanical and photonic devices in quartz. Using this approach, we demonstrate quartz nanomechanical cantilevers and ring resonators featuring Qs of 4900 and 8900, respectively.

Bulletin of Materials Science

Indian Academy of Sciences (India)

Effect of annealing on crystal size in pure Mysore silk fibres -- R Somashekar and R Gopalakrishna Urs .... DC sputtered Bi(Pb) SrCaCuO films on single (MgO and polycrystalline (MgO, ... Doppler-broadended positron annihilation studies in ...

Pulsed laser deposition of YBCO films on ISD MgO buffered metal tapes

CERN Document Server

Ma, B; Koritala, R E; Fisher, B L; Markowitz, A R; Erck, R A; Baurceanu, R; Dorris, S E; Miller, D J; Balachandran, U

2003-01-01

Biaxially textured magnesium oxide (MgO) films deposited by inclined-substrate deposition (ISD) are desirable for rapid production of high-quality template layers for YBCO-coated conductors. High-quality YBCO films were grown on ISD MgO buffered metallic substrates by pulsed laser deposition (PLD). Columnar grains with a roof-tile surface structure were observed in the ISD MgO films. X-ray pole figure analysis revealed that the (002) planes of the ISD MgO films are tilted at an angle from the substrate normal. A small full-width at half maximum (FWHM) of approx 9deg was observed in the phi-scan for ISD MgO films deposited at an inclination angle of 55deg . In-plane texture in the ISD MgO films developed in the first approx 0.5 mu m from the substrate surface, and then stabilized with further increases in film thickness. Yttria-stabilized zirconia and ceria buffer layers were deposited on the ISD MgO grown on metallic substrates prior to the deposition of YBCO by PLD. YBCO films with the c-axis parallel to the...

Influence of different ions doping on the antibacterial properties of MgO nanopowders

Energy Technology Data Exchange (ETDEWEB)

Rao, Yuanyuan; Wang, Wei, E-mail: weiwang@hust.edu.cn; Tan, Fatang; Cai, Yuncheng; Lu, Junwen; Qiao, Xueliang

2013-11-01

Compared with other inorganic antibacterial agents, magnesium oxide (MgO) nanopowders exhibit a unique antibacterial mechanism and various advantages in applications, having attracted extensive attention. In this study, MgO nanopowders doped with different ions (Li{sup +}, Zn{sup 2+} and Ti{sup 4+}) were synthesized by a sol–gel method, respectively. The structures and morphologies of the as-obtained precursors and nanopowders were characterized and confirmed by X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The influence of three metal ions doping on the antibacterial properties of MgO nanopowders was also investigated by their bactericidal activity against Escherichia coli (E. coli, ATCC 25922) using the broth microdilution method and the agar method. The results show that Li-doped MgO exhibits better antibacterial activity, Zn-doped and Ti-doped MgO display poorer antibacterial activity than pure MgO. It can be concluded that the influence of different ions doping on the antibacterial properties of MgO mainly lies on oxygen vacancies and basicity of nanopowders.

Magnetic structure of URhSi single crystal

Czech Academy of Sciences Publication Activity Database

Prokeš, K.; Andreev, Alexander V.; Honda, F.; Sechovský, V.

2003-01-01

Roč. 261, - (2003), s. 131-138 ISSN 0304-8853 R&D Projects: GA ČR GA202/02/0739 Institutional research plan: CEZ:AV0Z1010914 Keywords : URhSi single crystal * magnetization * neutron diffraction * magnetic structure determination Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.910, year: 2003

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....... 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...... 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...

Thermal stability of radiation-induced free radicals in γ-irradiated l-alanine single crystals

International Nuclear Information System (INIS)

Maltar-Strmecki, N.; Rakvin, B.

2005-01-01

Decay of the radiation-induced stable free radicals in l-alanine single crystals and powders at the temperatures from 379 to 476K was examined by electron paramagnetic resonance. For single crystals, the calculated activation energy of the radical decay is 104.3±1.7kJ/mol (i.e. 12 538+/-202K) and the frequency factor lnν 0 is 24.1±0.4min -1 . The lifetime of the radical in single crystals at 296K is 162 years. The results confirm the long-term stability of the radicals, but the decay was found to be faster in large crystals than in powders

Growth Aspects, Structural and Optical Properties of 2-aminopyridinium 2,4 Dinitrophenolate Single Crystal

Directory of Open Access Journals (Sweden)

S. Reena Devi

2017-06-01

Full Text Available Organic single crystal of 2-aminopyridinium 2,4-dinitrophenolate single crystal was grown by slow evaporation technique. The cell parameters and space group (P were determined from single X-ray diffraction analysis. HRXRD studies ascertained the crystalline quality. UV-Visible and PL spectral studies revealed the emission in red region, transparency (75% cutoff wavelength around 440 nm respectively. The laser damage threshold of grown crystal was estimated by using Nd:YAG laser beam and these results were mutually related with specific heat capacity of the grown crystal. The third-order nonlinear optical parameters were estimated by Z-scan technique which is useful for optical applications.

Effect of grain boundary on the field-effect mobility of microrod single crystal organic transistors.

Science.gov (United States)

Kim, Jaekyun; Kang, Jingu; Cho, Sangho; Yoo, Byungwook; Kim, Yong-Hoon; Park, Sung Kyu

2014-11-01

High-performance microrod single crystal organic transistors based on a p-type 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) semiconductor are fabricated and the effects of grain boundaries on the carrier transport have been investigated. The spin-coating of C8-BTBT and subsequent solvent vapor annealing process enabled the formation of organic single crystals with high aspect ratio in the range of 10 - 20. It was found that the organic field-effect transistors (OFETs) based on these single crystals yield a field-effect mobility and an on/off current ratio of 8.04 cm2/Vs and > 10(5), respectively. However, single crystal OFETs with a kink, in which two single crystals are fused together, exhibited a noticeable drop of field-effect mobility, and we claim that this phenomenon results from the carrier scattering at the grain boundary.

Modeling Nonlinear Elastic-plastic Behavior of RDX Single Crystals During Indentation

Science.gov (United States)

2012-01-01

single crystals has also been probed using shock experiments (6, 12) and molecular dynamics simulations (12–14). RDX undergoes a polymorphic phase...Patterson, J.; Dreger, Z.; Gupta, Y. Shock-wave Induced Phase Transition in RDX Single Crystals. J. Phys. Chem. B 2007, 111, 10897–10904. 17. Bedrov, D...and Volume Compression of β - HMX and RDX . In Proc. Int. Symp. High Dynamic Pressures; Commissariat a l’Energie Atomique: Paris, 1978; pp 3–8. 24

Room temperature exchange bias in SmFeO_3 single crystal

International Nuclear Information System (INIS)

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

2016-01-01

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

A diamond-anvil high-pressure cell for X-ray diffraction on a single crystal

International Nuclear Information System (INIS)

Malinowski, M.

1987-01-01

A new diamond-anvil high-pressure cell is described which can be used in single-crystal X-ray diffraction instruments to collect X-ray intensity data from single-crystal samples up to hydrostatic pressures of about 10 GPa. A unique design allows two types of diffraction geometry to be applied in single-crystal high-pressure diffraction experiments. More than 85% of the Ewald sphere is accessible, and a continuous range of 2θ values is available from 0 up to about 160 0 . Pressure may be calibrated by the ruby fluorescence technique or by the use of an internal X-ray-standard single crystal. The design of our diamond-anvil cell would allow, with little or no modification, operation at high and low temperatures, optical studies and powder diffractometer work. (orig.)

Characteristics evaluation of stilbene single crystal grown by vertical bridgman technique

International Nuclear Information System (INIS)

Jo, Kwang Ho

2012-02-01

As the nature of organic scintillator, stilbene single crystal's decay time is only a couple of nano seconds, which makes it suitable for fast neutron detection. However, the entire amount of stilbene single crystal being used relies on import currently. As the necessity of fast neutron detection equipment such as KSTAR and Sodium-cooled Fast Reactor system increases, the goal is to have our own domestic technology through the growth of stilbene single crystal. The emission wavelength of grown stilbene single crystal is confirmed, and the property of grown stilbene single crystal is assessed compared to commercial stilbene (Ukraine ISMA research center) through gamma ray and neutron tests. In this research, we have grown stilbenes through Bridgman technique, and obtained three stilbenes out of two amples. (Two ones of Φ 30 mm x 15 mm, and Φ 40 mm x 17 mm from the first ample, and size of Φ 25 mm x 13 mm from the other) The grown stilbene's emission wavelength and inherent property of stilbene are confirmed. As the result of gamma ray test, we have confirmed linearity of grown stilbene's scintillator, and the relative light yield ratio is proven 101% efficiency to reference stilbene. Neutron detection efficiency of the three stilbenes amounts to 80% of reference stilbene, and FOM of them is 108% efficiency to reference stilbene's one. Although Ukraine ISMA research center still holds a dominant position with world-class efficiency and performance of its stilbene, we expect to produce a better stilbene with our domestic technology development. Through this, fast neutron detection technique can be obtained, which opens up an opportunity to be used not only in neutron monitoring system in nuclear fusion reactor, but also in alternative measurement technique as the unit price of He-3 increases recently

Recent progress in large grain/single crystal high RRR niobium

International Nuclear Information System (INIS)

Ganapati Rao Myneni; Peter Kneisel; Tadeu Carneiro; S.R. Agnew; F. Stevie

2005-01-01

High RRR bulk niobium Superconducting Radio Frequency (SRF) cavity technology is chosen for the International Linear Collider (ILC). The SRF community was convinced until now that fine grain polycrystalline RRR niobium sheets obtained via forging and cross rolling are essential for forming the SRF Cavities. However, it was recently discovered under a joint Reference Metals Company, Inc., - JLAB CRADA that large grain/single crystal RRR niobium sliced directly from ingots is highly ductile reaching 100 percent elongation. This discovery led to the successful fabrication of several SRF single and/or multi cell structures, formed with sliced RRR discs from the ingots, operating at 2.3, 1.5 and 1.3 GHz. This new exciting development is expected to offer high performance accelerator structures not only at reduced costs but also with simpler fabrication and processing conditions. As a result there is a renewed interest in the evaluation and understanding of the large grain and single crystal niobium with respect to their mechanical and physical properties as well as the oxidation behavior and the influence of impurities such as hydrogen and Ta. In this paper the results of many collaborative studies on large grain and single crystal high RRR niobium between JLAB, Universities and Industry are presented