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 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.

Large-scale single-crystal growth of (CH3)2NH2CuCl3 for neutron scattering experiments

Science.gov (United States)

Park, Garam; Oh, In-Hwan; Park, J. M. Sungil; Park, Seong-Hun; Hong, Chang Seop; Lee, Kwang-Sei

2016-05-01

Neutron scattering studies on low-dimensional quantum spin systems require large-size single-crystals. Single-crystals of (CH3)2NH2CuCl3 showing low-dimensional magnetic behaviors were grown by a slow solvent evaporation method in a two-solvent system at different temperature settings. The best results were obtained for the bilayer solution of methanol and isopropanol with a molar ratio of 2:1 at 35 °C. The quality of the obtained single-crystals was tested by powder and single-crystal X-ray diffraction and single-crystal neutron diffraction. In addition, to confirm structural phase transitions (SPTs), thermal analysis and single-crystal X-ray diffraction at 300 K and 175 K, respectively, were conducted, confirming the presence of a SPT at Tup=288 K on heating and Tdown=285 K on cooling.

Structural, magnetic and electrical properties of the hexagonal ferrites MFeO3 (M=Y, Yb, In)

International Nuclear Information System (INIS)

Downie, Lewis J.; Goff, Richard J.; Kockelmann, Winfried; Forder, Sue D.; Parker, Julia E.; Morrison, Finlay D.; Lightfoot, Philip

2012-01-01

The hexagonal ferrites MFeO 3 (M=Y, Yb, In) have been studied using a combination of neutron and X-ray powder diffraction, magnetic susceptibility, dielectric measurements and 57 Fe Mössbauer spectroscopy. This study confirms the previously reported crystal structure of InFeO 3 (YAlO 3 structure type, space group P6 3 /mmc), but YFeO 3 and YbFeO 3 both show a lowering of symmetry to at most P6 3 cm (ferrielectric YMnO 3 structure type). However, Mössbauer spectroscopy shows at least two distinct Fe sites for both YFeO 3 and YbFeO 3 and we suggest that the best model to rationalise this involves phase separation into more than one similar hexagonal YMnO 3 -like phase. Rietveld analysis of the neutron diffraction data was carried out using two hexagonal phases as a simplest case scenario. In both YFeO 3 and YbFeO 3 , distinct dielectric anomalies are observed near 130 K and 150 K, respectively. These are tentatively correlated with weak anomalies in magnetic susceptibility and lattice parameters, for YFeO 3 and YbFeO 3 , respectively, which may suggest a weak magnetoelectric effect. Comparison of neutron and X-ray powder diffraction shows evidence of long-range magnetic order in both YFeO 3 and YbFeO 3 at low temperatures. Due to poor sample crystallinity, the compositional and structural effects underlying the phase separation and possible magnetoelectric phenomena cannot be ascertained. - Graphical abstract: Hexagonal MFeO 3 (M=Y, Yb) exhibit phase separation into two YMnO 3 -like phases. Variable temperature crystallographic, electrical and magnetic studies suggest weak correlations between electrical and magnetic responses and long-range magnetic order at low temperature. Highlights: ► Multi-technique study of multiferroic hexagonal MFeO 3 . ► Phase separation into two similar hexagonal phases. ► Weak coupling of electrical and magnetic responses. ► Long-range magnetic order at low T.

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

Lattice effects in HoVo(3) single crystal

NARCIS (Netherlands)

Sikora, M.; Marquina, C.; Ibarra, M. R.; Nugroho, A. A.; Palstra, T. T. M.

We report the study of lattice effects in the Mott insulator HoVO3 performed by means of linear thermal expansion on a single crystal in the temperature range 10-290 K. The holmium orthovanadate HoVO3 reveals gradual orbital ordering (OO) below T-OO = 200K and orders antiferromagnetically at T-N =

Tunable bandgap in hybrid perovskite CH3NH3Pb(Br3−yXy single crystals and photodetector applications

Directory of Open Access Journals (Sweden)

L. Wang

2016-04-01

Full Text Available We report the synthesis of CH3NH3Pb(Br3−yXy (X=Cl and I single crystals via a stepwise temperature control approach. High-quality CH3NH3Pb(Br3−yXy crystals with a tunable bandgap from 1.92eV to 2.53eV have been prepared successfully in this way. And further experiments revealed the influence of halogen content and preparation temperature on the structural and optical properties of these crystals. It is observed that chlorine can lower the critical nucleation energy, which results in crystallizing at lower temperature with the chlorine content increasing, while the nucleation energy increases slowly with increasing iodine content. Moreover, in contrast to Frank–van der Merwe growth with low heating rate, high heating rate leads to a mass of small size single crystals and Stranski-Krastanov growth. The single crystals with tunable band gap and impressive characteristics enable us to fabricate high performance photodetectors for different wavelengths.

Spontaneous and stimulated emission in Sm3+-doped YAl3(BO3)4 single crystal

International Nuclear Information System (INIS)

Ryba-Romanowski, Witold; Lisiecki, Radosław; Beregi, Elena; Martín, I.R.

2015-01-01

Single crystals of YAl 3 (BO 3 ) 4 doped with trivalent samarium were grown by the top-seeded high temperature solution method and their absorption and emission spectra were investigated. Optical pumping into prominent absorption band around 405 nm feeds the 4 G 5/2 metastable level giving rise to intense visible luminescence distributed in several spectral lines with the most intense line around 600 nm characterized by a branching ratio of 0.42 and peak emission cross section of 0.25×10 −20 cm 2 . Optical amplification at 600 nm with a gain coefficient of 2.9 cm −1 was achieved during a pump-and-probe experiment. - Highlights: • YAB:Sm crystal grown by the top-seeded high temperature solution method. • Spectroscopic qualities relevant for visible laser operation. • YAB:Sm single crystal used in a pump-and-probe experiment. • Optical amplification properties of samarium doped YAl 3 (BO 3 ) 4

Ellipsometric studies of ErMnO₃ single crystals

DEFF Research Database (Denmark)

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

2007-01-01

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

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.

Crystallographic Investigations into Properties of Acentric Hybrid Perovskite Single Crystals NH(CH3)3SnX3(X = Cl, Br)

KAUST Repository

Dang, Yangyang

2016-10-11

The hybrid perovskites with special optoelectronic properties have attracted more attention to the scientific and industrial applications. However, because of the toxicity and instability of lead complexes, there is interest in finding a nontoxic substitute for the lead in the halides perovskites and solving the ambiguous crystal structures and phase transition of NH(CH3)3SnX3 (X = Cl, Br). Here, we report the bulk crystal growths and different crystal morphologies of orthorhombic hybrid perovskites NH(CH3)3SnX3 (X = Cl, Br) in an ambient atmosphere by bottom-seeded solution growth (BSSG) method. More importantly, detailed structural determination and refinements, phase transition, band gap, band structure calculations, nonlinear optical (NLO) properties, XPS, thermal properties, and stability of NH(CH3)3SnX3 (X = Cl, Br) single crystals are demonstrated. NH(CH3)3SnCl3 single crystal undergoes reversible structural transformation from orthorhombic space group Cmc21 (no. 36) to monoclinic space group Cc (no. 9) and NH(CH3)3SnBr3 belongs to the orthorhombic space group Pna21 (no. 33) by DSC, single-crystal X-ray diffraction and temperature-dependent SHG measurements, which clarify the former results. These results should pave the way for further studies of these materials in optoelectronics.

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.

Aging characteristics of 0.7Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.3PbTiO{sub 3} single crystals with different crystal orientations

Energy Technology Data Exchange (ETDEWEB)

Liu, Xing [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Changzhou (China); Chinese Academy of Sciences, Key Laboratory of Inorganic Function Material and Device, Shanghai (China); Wu, Dun; Fang, Bijun [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Changzhou (China); Ding, Jianning [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Changzhou (China); Jiangsu University, School of Material Science and Engineering, Zhenjiang (China); Li, Xiaobing; Zhao, Xiangyong; Luo, Haosu [Chinese Academy of Sciences, Key Laboratory of Inorganic Function Material and Device, Shanghai (China); Ko, Jae-Hyeon [Hallym University, Department of Physics, Chuncheon (Korea, Republic of); Ahn, Chang Won [University of Ulsan, Department of Physics and EHSRC, Ulsan (Korea, Republic of)

2015-06-15

In this work, the time and temperature dependence of the piezoelectric and ferroelectric properties of the 0.7Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.3PbTiO{sub 3} (0.7PMN-0.3PT) single crystals were investigated in order to search for an effective method to improve their properties further. The piezoelectric properties of the [001]-, [110]- and [111]-oriented 0.7PMN-0.3PT single crystals exhibit excellent time stability during the 2-month room-temperature aging process. The re-poling process leads to the improvement of piezoelectric constant d{sub 33} for the [001]-, [110]- and [111]-oriented 0.7PMN-0.3PT single crystals, while the values of electromechanical coupling coefficient k{sub t} change little. During the thermal aging, the values of the measured d{sub 33}, calculated converse piezoelectric constant d{sub 33}{sup *}, maximum strain S{sub max}% and longitudinal electrostrictive coefficient Q of the [001]-, [110]- and [111]-oriented crystal plates increase gradually before the ferroelectric phase transition temperatures (T{sub FPT}, T{sub R-M}, T{sub R-O} and T{sub R-T}) and then decline continuously. The increase in these values before the T{sub FPT} is a result of the phase instability. In general, the [001]- and [110]-oriented 0.7PMN-0.3PT single crystals exhibit large piezoelectricity, excellent time stability and relatively high thermal stability between 20 and 80 C, which is favorable to the piezoelectric applications. (orig.)

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

Large rotating magnetocaloric effect in ErAlO3 single crystal

Directory of Open Access Journals (Sweden)

X. Q. Zhang

2017-05-01

Full Text Available Magnetic and magnetocaloric properties of ErAlO3 single crystal were investigated. Magnetization of ErAlO3 shows obvious anisotropy when magnetic field is applied along the a, b and c axes, which leads to large anisotropic magnetic entropy change. In particular, large rotating field entropy change from the b to c axis within the bc plane is obtained and reaches 9.7 J/kg K at 14 K in a field of 5 T. This suggests the possibility of using ErAlO3 single crystal for magnetic refrigerators by rotating its magnetization vector rather than moving it in and out of the magnet.

Magnetic order of Nd5Pb3 single crystals

Science.gov (United States)

Yan, J.-Q.; Ochi, M.; Cao, H. B.; Saparov, B.; Cheng, J.-G.; Uwatoko, Y.; Arita, R.; Sales, B. C.; Mandrus, D. G.

2018-04-01

We report millimeter-sized Nd5Pb3 single crystals grown out of a Nd-Co flux. We experimentally study the magnetic order of Nd5Pb3 single crystals by measuring the anisotropic magnetic properties, electrical resistivity under high pressure up to 8 GPa, specific heat, and neutron single crystal diffraction. Two successive magnetic orders are observed at T N1  =  44 K and T N2  =  8 K. The magnetic cells can be described with a propagation vector k=(0.5, 0, 0) . Cooling below T N1, Nd1 and Nd3 order forming ferromagnetic stripes along the b-axis, and the ferromagnetic stripes are coupled antiferromagnetically along the a-axis for the k=(0.5, 0, 0) magnetic domain. Cooling below T N2, Nd2 orders antiferromagnetically to nearby Nd3 ions. All ordered moments align along the crystallographic c-axis. The magnetic order at T N1 is accompanied by a quick drop of electrical resistivity upon cooling and a lambda-type anomaly in the temperature dependence of specific heat. At T N2, no anomaly was observed in electrical resistivity but there is a weak feature in specific heat. The resistivity measurements under hydrostatic pressures up to 8 GPa suggest a possible phase transition around 6 GPa. Our first-principles band structure calculations show that Nd5Pb3 has the same electronic structure as does Y5Si3 which has been reported to be a one-dimensional electride with anionic electrons that do not belong to any atom. Our study suggests that R 5Pb3 (R  =  rare earth) can be a materials playground for the study of magnetic electrides. This deserves further study after experimental confirmation of the presence of anionic electrons.

Low-leakage superconducting tunnel junctions with a single-crystal Al{sub 2}O{sub 3} barrier

Energy Technology Data Exchange (ETDEWEB)

Oh, S [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Department of Physics, University of Illinois, Urbana, IL 61801 (United States); Cicak, K; Osborn, K D; Simmonds, R W; Pappas, D P [National Institute of Standards and Technology, Boulder, CO 80305 (United States); McDermott, R; Cooper, K B; Steffen, M; Martinis, J M [University of California, Santa Barbara, CA 93106 (United States)

2005-10-01

We have developed a two-step growth scheme for single-crystal Al{sub 2}O{sub 3} tunnel barriers. The barriers are epitaxially grown on single-crystal rhenium (Re) base electrodes that are grown epitaxially on a sapphire substrate, while polycrystalline Al is used as the top electrode. We show that by first growing an amorphous aluminium (Al) oxide layer at room temperature and crystallizing it at a high temperature in oxygen environment, a morphologically intact single-crystal Al{sub 2}O{sub 3} layer is obtained. Tunnel junctions fabricated from these trilayers show very low subgap leakage current. This single-crystal Al{sub 2}O{sub 3} junction may open a new venue for coherent quantum devices.

Synthesis and growth of single crystals of PrCl3

International Nuclear Information System (INIS)

Pei, Jen Shieh.

1984-01-01

An efficient method for growth of high optical quality single crystals of PrCl 3 . The method consists in careful drying of the hydrated chloride, PrCl 3 . 7H 2 O, with a protective atmosphere of anhydrous HCl and Ar. A subsequent growth was done by the zone melting technique. The hydrated chloride had prepared from dissolution of the oxide Pr 6 O 11 in hydrochloric acid. The grown crystals had characterized fluorescence and x-ray diffraction measurements. (Author) [pt

Synthesis and single crystal growth of perovskite semiconductor CsPbBr3

Science.gov (United States)

Zhang, Mingzhi; Zheng, Zhiping; Fu, Qiuyun; Chen, Zheng; He, Jianle; Zhang, Sen; Chen, Cheng; Luo, Wei

2018-02-01

As a typical representative of all-inorganic lead halide perovskites, cesium lead bromine (CsPbBr3) has attracted significant attention in recent years. The direct band gap semiconductor CsPbBr3 has a wide band gap of 2.25 eV and high average atomic number (Cs: 55, Pb: 82 and Br: 35), which meet most of the requirements for detection of X- and γ-ray radiation, such as high attenuation, high resistivity, and significant photoconductivity response. However, the growth of large volume CsPbBr3 single crystals remains a challenge. In this paper, the synthesis of CsPbBr3 polycrystalline powders by a chemical co-precipitation method was investigated and the optimum synthesis conditions were obtained. A large CsPbBr3 single crystal of 8 mm diameter and 60 mm length was obtained by a creative electronic dynamic gradient (EDG) method. X-ray diffraction (XRD) patterns and X-ray rocking curve showed that the CsPbBr3 crystal preferentially oriented in the (1 1 0) direction and had a low dislocation density and small residual stress in the crystal. The IR and UV-Vis transmittance and temperature-dependent photoluminescence (PL) spectra showed the crystal had a good basic optical performance. The almost linear current-voltage (I-V) curves implied good ohmic contact between the electrodes and crystal surfaces. The resistivity of the crystal was calculated 109-1010 Ω cm. The above results showed that the quality of the obtained crystal had met the demand of optoelectronic applications.

Phonon anomalies in optical spectra of LiNbO3 single crystals

Directory of Open Access Journals (Sweden)

ANDREJA VALCIC

2004-06-01

Full Text Available LiNbO3 single crystals were grown by the Czochralski technique in an air atmosphere. The critical crystal diameter Dc = 1.5 cm and the critical rate of rotation wc = 35 rpm were calculated by equations from the hydrodynamics of the melt. The domain inversion was carried out at 1430 K using a 3.75 V/cm electric field for 10 min. The obtained crystals were cut, polished and etched to determine the presence of dislocations and single domain structures. The optical properties were studied by infrared and Raman spectroscopy as a function of temperature. With decreasing temperature, an atypical behaviour of the phonon modes could be seen in the ferroelectrics LiNbO3. The obtained results are discussed and compared with published data.

Giant anisotropy of magnetocaloric effect in TbMnO3 single crystals

Science.gov (United States)

Jin, Jin-Ling; Zhang, Xiang-Qun; Li, Guo-Ke; Cheng, Zhao-Hua; Zheng, Lin; Lu, Yi

2011-05-01

The magnetocaloric effect (MCE) in TbMnO3 single crystals was investigated by isothermal magnetization curves for the ab plane at low temperatures. Large magnetic entropy change, ΔSM = -18.0 J/kg K, and the refrigerant capacity, RC = 390.7 J/kg, are achieved near the ordering temperature of Tb3+ moment (TNTb) under 70 kOe along the a axis. Furthermore, the TbMnO3 single crystal exhibits a giant MCE anisotropy. The difference of ΔSMand RC between the a and b axes is field and temperature dependent, which reaches maximum values of 11.4 J/kg K and 304.1 J/kg, respectively. By taking magnetocrystalline anisotropy into account, the rotating ΔSMwithin the ab plane can be well simulated, indicating that the anisotropy of ΔSMis directly contributed from the magnetocrystalline anisotropy. Our finding for giant MCE anisotropy in TbMnO3 single crystals explores the possibility of using this material for magnetic refrigerators by rotating its magnetization vector rather than moving it in and out of the magnet.

Optical characteristics of BaGa2S4:Ho3+ and BaGa2Se4:Ho3+ single crystals

International Nuclear Information System (INIS)

Choe, Sung-Hyu; Jin, Moon-Seog; Kim, Wha-Tek

2005-01-01

BaGa 2 S 4 , BaGa 2 S 4 :Ho 3+ , BaGa 2 Se 4 , and BaGa 2 Se 4 :Ho 3+ single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the single crystals were investigated in the temperature region from 11 K to 300 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Two broad emission bands were observed in the photoluminescence spectra of the single crystals. These bands were attributed to donor-acceptor pair recombinations. Sharp emission peaks were observed in the BaGa 2 S 4 :Ho 3+ and the BaGa 2 Se 4 :Ho 3+ single crystals and were assigned to radiation recombination between split Stark levels of Ho 3+ .

Crystal Growth of Ca3Nb(Ga1−xAlx3Si2O14 Piezoelectric Single Crystals with Various Al Concentrations

Directory of Open Access Journals (Sweden)

Yuui Yokota

2015-08-01

Full Text Available Ca3Nb(Ga1−xAlx3Si2O14 (CNGAS single crystals with various Al concentrations were grown by a micro-pulling-down (µ-PD method and their crystal structures, chemical compositions, crystallinities were investigated. CNGAS crystals with x = 0.2, 0.4 and 0.6 indicated a single phase of langasite-type structure without any secondary phases. In contrast, the crystals with x = 0.8 and 1 included some secondary phases in addition to the langasite-type phase. Lattice parameters, a- and c-axes lengths, of the langasite-type phase systematically decreased with an increase of Al concentration. The results of chemical composition analysis revealed that the actual Al concentrations in as-grown crystals were almost consistent with the nominal compositions. In addition, there was no large segregation of each cation along the growth direction.

An EPMA study on KNbO3 and NaNbO3 single crystals - potential reference materials for quantitative microanalysis

International Nuclear Information System (INIS)

Samardzzija, Z.; Bernik, S.; Malic, B.; Ceh, M.; Marinenko, R.B.

2004-01-01

Single crystals of KNbO 3 and NaNbO 3 were selected from the limited number of suitable alkali compounds that are available and evaluated as possible reference materials for the electron-probe microanalysis (EPMA) of alkaline niobates with a composition described by the general formula K 1-x Na x NbO 3 . The EPMA study verified that KNbO 3 and NaNbO 3 single crystals are stable under the electron beam and compositionally homogeneous. A quantitative microanalysis confirmed the composition of pure KNbO 3 , while the NaNbO 3 crystal contained 0.3 mass fraction % of Ca. A significant improvement in the accuracy of the quantitative EPMA of polycrystalline potassium-sodium niobates was achieved using these single crystals as standards. The crystals can also be useful as reference materials for the analysis of sodium and potassium in other materials. (author)

Scintillation activity in an unirradiated single crystal of 3-hydroxyxanthine

International Nuclear Information System (INIS)

Cooke, D.W.; Jahan, M.S.; Alexander, C. Jr.

1976-01-01

A method of growing single crystals (approximately 4mm long) of 3-hydroxyxanthine is described. Observed scintillations occurring in an unirradiated single crystal of this potent oncogen as the temperature is lowered from 300 to 90 K are shown. It was found that these scintillations occur upon heating or cooling and do not diminish in activity as the number of heating and cooling cycles increase. It was found that a short duration u.v. exposure would terminate the scintillation activity and various attempts (such as annealing and pressure changes) to rejuvenate them were unsuccessful. With these observations in mind speculation is made concerning the mechanisms associated with the production of purine N-oxide derivatives. (U.K.)

A multistep single-crystal-to-single-crystal bromodiacetylene dimerization

Science.gov (United States)

Hoheisel, Tobias N.; Schrettl, Stephen; Marty, Roman; Todorova, Tanya K.; Corminboeuf, Clémence; Sienkiewicz, Andrzej; Scopelliti, Rosario; Schweizer, W. Bernd; Frauenrath, Holger

2013-04-01

Packing constraints and precise placement of functional groups are the reason that organic molecules in the crystalline state often display unusual physical or chemical properties not observed in solution. Here we report a single-crystal-to-single-crystal dimerization of a bromodiacetylene that involves unusually large atom displacements as well as the cleavage and formation of several bonds. Density functional theory computations support a mechanism in which the dimerization is initiated by a [2 + 1] photocycloaddition favoured by the nature of carbon-carbon short contacts in the crystal structure. The reaction proceeded up to the theoretical degree of conversion without loss of crystallinity, and it was also performed on a preparative scale with good yield. Moreover, it represents the first synthetic pathway to (E)-1,2-dibromo-1,2-diethynylethenes, which could serve as synthetic intermediates for the preparation of molecular carbon scaffolds. Our findings both extend the scope of single-crystal-to-single-crystal reactions and highlight their potential as a synthetic tool for complex transformations.

Lattice effects in HoVo3 single crystal

International Nuclear Information System (INIS)

Sikora, M.; Marquina, C.; Ibarra, M.R.; Nugroho, A.A.; Palstra, T.T.M.

2007-01-01

We report the study of lattice effects in the Mott insulator HoVO 3 performed by means of linear thermal expansion on a single crystal in the temperature range 10-290 K. The holmium orthovanadate HoVO 3 reveals gradual orbital ordering (OO) below T OO =200 K and orders antiferromagnetically at T N =113 K. A first-order structural phase transition takes place at T S ∼38 K, which is probably accompanied by change of the OO type and hence the type of antiferromagnetic spin ordering

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 ...

Confinement stabilises single crystal vaterite rods.

OpenAIRE

Schenk, AS; Albarracin, EJ; Kim, YY; Ihli, J; Meldrum, FC

2014-01-01

Single-crystals of vaterite, the least-stable anhydrous polymorph of CaCO3, are rare in biogenic and synthetic systems. We here describe the synthesis of high aspect ratio single crystal vaterite rods under additive-free conditions by precipitating CaCO3 within the cylindrical pores of track-etch membranes.

Crystal growth and scintillation properties of Pr-doped SrI2 single crystals

Science.gov (United States)

Yokota, Yuui; Ito, Tomoki; Yoshino, Masao; Yamaji, Akihiro; Ohashi, Yuji; Kurosawa, Shunsuke; Kamada, Kei; Yoshikawa, Akira

2018-04-01

Pr-doped SrI2 (Pr:SrI2) single crystals with various Pr concentrations were grown by the halide-micro-pulling-down (H-μ-PD) method, and the scintillation properties were investigated. Pr1%:SrI2 single crystal with high transparency could be grown by the H-μ-PD method while Pr2, 3 and 5%:SrI2 single crystals included some cracks and opaque parts. In the photoluminescence spectrum of the Pr1%:SrI2 single crystal, an emission peak originated from the Pr3+ ion was observed around 435 nm while the radioluminescence spectra showed an emission peak around 535 nm for the undoped SrI2 and Pr:SrI2 single crystals. Light yields of Pr1, 2, 3 and 5%:SrI2 single crystals under γ-ray irradiation were 7700, 8700, 7200 and 6700 photons/MeV, respectively. Decay times of Pr1 and 2%:SrI2 single crystals under γ-ray irradiation were 55.9 and 35.0 ns of the fast decay component, and 435 and 408 ns of the slow decay component, respectively.

Growth and characterization of lead-free (K,Na)NbO3-based piezoelectric single crystals

International Nuclear Information System (INIS)

Liu, Hairui

2016-01-01

Lead-free piezoelectric materials have received increasing attention in the last decade, driven by environmental issues and health concerns. Of considerable interest is the (K,Na)NbO 3 (KNN)-based system, which possesses a relatively high Curie temperature and good piezoelectric properties. Abundant publications on KNN-based polycrystalline ceramics increased the interest in studying their single-crystalline form, based on two major concerns. The first concern refers to the negative role of grain interactions on the electromechanical response. The second concern deals with domain engineering. The relationship between external electric field direction, crystallographic orientation, and spontaneous polarization vectors for a specific structure can be more readily established in single crystals and thus offers a pathway for an in-depth understanding of fundamental mechanism and potential applications. The exciting enhancement of both piezoelectric and ferroelectric response in lead-based single crystals also encourages the further exploration of KNN-based piezoelectric crystals, as they possess the same perovskite structure. The main goal of this thesis is to find possible approaches for improved electromechanical properties in KNN-based piezoelectric single crystals. In Chapter 2, the current development of KNN-based single crystals as piezoelectrics is reviewed, following a short introduction of fundamental knowledge on piezoelectrics and ferroelectrics. Both submerged-seed solution growth and top-seeded solution growth techniques were employed to produce single crystals, as described detailed in Chapter 3. Emphasis is subsequently placed on issues of the crystal growth process, effective methods to enhance electrical properties, and crystallographic orientation-dependent electrical properties in Li-, Ta-, and/or Sb-substituted KNN single crystals. The main conclusions from the crystal growth aspect are presented in Chapter 4 and can be summarized as follows: (i

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-09-15

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

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

KAUST Repository

Chao, Chunying; Ren, Zhaohui; Zhu, Yihan; Xiao, Zhen; Liu, Zhenya; Xú , Gang; Mai, Jiangquan; Li, Xiang; Shen, Ge; Han, Gaorong

2012-01-01

Free-standing single-crystal PbTiO 3 nanoplates (see picture) were synthesized by a facile hydrothermal method. A "self-templated" crystal growth is presumed to lead to the formation of the PbTiO 3 nanoplates, which have ferroelectric single

Distributed Feedback Laser Based on Single Crystal Perovskite

Science.gov (United States)

Sun, Shang; Xiao, Shumin; Song, Qinghai

2017-06-01

We demonstrate a single crystal perovskite based, with grating-structured photoresist on top, highly polarized distributed feedback laser. A lower laser threshold than the Fabry-Perot mode lasers from the same single crystal CH3NH3PbBr3 microplate was obtained. Single crystal CH3NH3PbBr3 microplates was synthesized with one-step solution processed precipitation method. Once the photoresist on top of the microplate was patterned with electron beam, the device was realized. This one-step fabrication process utilized the advantage of single crystal to the greatest extend. The ultra-low defect density in single crystalline microplate offer an opportunity for lower threshold lasing action compare with poly-crystal perovskite films. In the experiment, the lasing action based on the distributed feedback grating design was found with lower threshold and higher intensity than the Fabry-Perot mode lasers supported by the flat facets of the same microplate.

Magnetocaloric properties of the hexagonal HoMnO{sub 3} single crystal revisited

Energy Technology Data Exchange (ETDEWEB)

Balli, M., E-mail: Mohamed.balli@Usherbrooke.ca [Regroupement québécois sur les matériaux de pointe, Département de physique, Université de Sherbrooke, QC, Canada J1K 2R1 (Canada); Roberge, B.; Vermette, J.; Jandl, S. [Regroupement québécois sur les matériaux de pointe, Département de physique, Université de Sherbrooke, QC, Canada J1K 2R1 (Canada); Fournier, P. [Regroupement québécois sur les matériaux de pointe, Département de physique, Université de Sherbrooke, QC, Canada J1K 2R1 (Canada); Canadian Institute for Advanced Research, Toronto, Ontario, Canada M5G 1Z8 (Canada); Gospodinov, M.M. [Institute of Solid State Physics, Bulgarian Academy of Science, Sofia 1184 (Bulgaria)

2015-12-01

Magnetic and magnetocaloric properties of the hexagonal HoMnO{sub 3} single crystal have been revisited. It was found that the magnetocaloric effect shown by HoMnO{sub 3} strongly depends on the crystal orientation in respect to the applied magnetic field. Consequently, a large thermal effect can be induced by spinning the single crystal HoMnO{sub 3} around the a (or b) axis in a constant magnetic field instead of the conventional magnetization–demagnetization process. Under 7 T, the maximum rotating entropy change was evaluated to be about 8 J/kg K. The associated adiabatic temperature change reaches a value of about 5 K. These values are comparable to those of the other oxides exhibiting a large rotating magnetocaloric effect. The presence of both conventional and rotating thermal effects makes the hexagonal HoMnO{sub 3} more interesting from a practical point of view.

Synthesis and Single Crystal Structures of Substituted-1,3-Selenazol-2-amines

Directory of Open Access Journals (Sweden)

Guoxiong Hua

2016-12-01

Full Text Available The synthesis and X-ray single crystal structures of a series of new 4-substituted-1,3-selenazol-2-amines is reported. The efficient preparation of these compounds was carried out by two-component cyclization of the selenoureas with equimolar amounts of α-haloketones. The selenoureas were obtained from the reaction of Woollins’ reagent with cyanamides, followed by hydrolysis with water. All new compounds have been characterized by IR spectroscopy, multi-NMR (1H, 13C, 77Se spectroscopy, accurate mass measurement and single crystal X-ray structure analysis.

Single crystalline Co3O4 nanocrystals exposed with different crystal planes for Li-O2 batteries.

Science.gov (United States)

Su, Dawei; Dou, Shixue; Wang, Guoxiu

2014-08-29

Single crystalline Co3O4 nanocrystals exposed with different crystal planes were synthesised, including cubic Co3O4 nanocrystals enclosed by {100} crystal planes, pseudo octahedral Co3O4 enclosed by {100} and {110} crystal planes, Co3O4 nanosheets exposed by {110} crystal planes, hexagonal Co3O4 nanoplatelets exposed with {111} crystal planes, and Co3O4 nanolaminar exposed with {112} crystal planes. Well single crystalline features of these Co3O4 nanocrystals were confirmed by FESEM and HRTEM analyses. The electrochemical performance for Li-O2 batteries shows that Co3O4 nanocrystals can significantly reduce the discharge-charge over-potential via the effect on the oxygen evolution reaction (OER). From the comparison on their catalytic performances, we found that the essential factor to promote the oxygen evolution reactions is the surface crystal planes of Co3O4 nanocrystals, namely, crystal planes-dependent process. The correlation between different Co3O4 crystal planes and their effect on reducing charge-discharge over-potential was established: {100} < {110} < {112} < {111}.

Preparation of TiC single crystals

International Nuclear Information System (INIS)

Scheerer, B.; Fink, J.; Reichardt, W.

1975-07-01

TiC single crystals were prepared by vertical zone melting for measurements of the phonon dispersion by inelastic neutron scattering. The influence of the starting material and of the growing conditions on the growth of the crystal were studied. The crystals were characterized by chemical methods, EMX and neutron diffraction. It was possible to grow single crystals with a volume of up to 0.6 cm 3 and mosaic spread of less then 0.4 0 . (orig.) [de

Single crystal growth, magnetic and thermal properties of perovskite YFe{sub 0.6}Mn{sub 0.4}O{sub 3} single crystal

Energy Technology Data Exchange (ETDEWEB)

Xie, Tao [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China); Synthetio Single Crystal Research Center, Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China); Key Laboratory of Transparent and Opto-functional Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Shen, Hui, E-mail: hshen@sit.edu.cn [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China); Zhao, Xiangyang; Man, Peiwen [Synthetio Single Crystal Research Center, Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China); Key Laboratory of Transparent and Opto-functional Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Wu, Anhua, E-mail: wuanhua@mail.sic.ac.cn [Synthetio Single Crystal Research Center, Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China); Key Laboratory of Transparent and Opto-functional Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Su, Liangbi [Synthetio Single Crystal Research Center, Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China); Key Laboratory of Transparent and Opto-functional Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Xu, Jiayue, E-mail: xujiayue@sit.edu.cn [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China)

2016-11-01

High quality YFe{sub 0.6}Mn{sub 0.4}O{sub 3} single crystal was grown by floating zone technique using a four-mirror-image-furnace under flowing air. Powder X-ray diffraction gives well evidence that the specimen has an orthorhombic structure, with space group Pbnm. Temperature dependence of the magnetizations of YFe{sub 0.6}Mn{sub 0.4}O{sub 3} single crystal were studied under ZFC and FC modes in the temperature range from 5 K to 400 K. A clear spin reorientation transition behavior (Γ{sub 4}→Γ{sub 1}) is observed in the temperature range of 322–316 K, due to the substitution of Mn at the Fe site of YFeO{sub 3}. Its Néel temperature is around 385 K. Moreover, the spin reorientation is verified by the change of magnetic hysteresis loops of the sample along [001] axis in the temperature range of 50–385 K. The thermal properties of the sample were measured by the differential scanning calorimeter (DSC) from 300 K to 500 K, which also clearly appear anomaly in the spin reorientation region. - Highlights: • High quality YFe{sub 0.6}Mn{sub 0.4}O{sub 3} single crystal was grown by floating zone technique. • The thermal properties appear anomaly in the spin reorientation region. • A clear spin reorientation transition behavior (Γ{sub 4}→Γ{sub 1}) is observed in the temperature range of 322–316 K, due to the substitution of Mn at the Fe site of YFeO{sub 3}.

Relaxor-PT Single Crystal Piezoelectric Sensors

Directory of Open Access Journals (Sweden)

Xiaoning Jiang

2014-07-01

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

Magnetic susceptibility of LaxCe1-xF3 single crystals

International Nuclear Information System (INIS)

Paradowski, M.L.; Pacyna, A.W.; Bombik, A.; Korczak, W.; Korczak, S.Z.

2000-01-01

The magnetic susceptibility of La x Ce 1-x F 3 single crystals, for 0 eff and paramagnetic Curie temperature θ p have been obtained, using the Curie-Weiss law in the temperature range 100-300 K. The interconfiguration excited energy E ex , the spin-fluctuation temperature T sf , and the g-values, corresponding to three Kramers doublets in the 2 F 5/2 ground multiplet of Ce 3+ ion in La x Ce 1-x F 3 have been determined, using quantum theory of paramagnetic susceptibility. The mixed-valent and crystal field effects influence significantly the g-values. The effect of the dilution of the paramagnetic Ce 3+ ions with diamagnetic La 3+ ions is also discussed

Electrically Anisotropic Layered Perovskite Single Crystal

KAUST Repository

Li, Ting-You

2016-01-01

-23). However, the difficulty in growing large-sized LOIHPs single crystal with superior electrical properties limits their practical applications. Here, we report a method to grow the centimeter-scaled LOIHP single crystal of [(HOC2H4NH3)2PbI4], demonstrating

Tl{sub 10}Hg{sub 3}Cl{sub 16}: Single crystal growth, electronic structure and piezoelectric properties

Energy Technology Data Exchange (ETDEWEB)

Khyzhun, O.Y., E-mail: khyzhun@ipms.kiev.ua [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky Street, 03142 Kyiv (Ukraine); Piasecki, M. [Institute of Physics, J.Dlugosz University Częstochowa, Armii Krajowej 13/15, Częstochowa PL-42-217 (Poland); Kityk, I.V. [Electrical Engineering Department, Częstochowa University Technology, Armii Krajowej 17, PL-42-200 Częstochowa (Poland); Luzhnyi, I. [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky Street, 03142 Kyiv (Ukraine); Fedorchuk, A.O. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, 50 Pekarska Street, 79010 Lviv (Ukraine); Fochuk, P.M. [Yuriy Fed’kovych Chernivtsi National University, 2 Kotziubynskoho Street, 58012 Chernivtsi (Ukraine); Levkovets, S.I. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, 13 Voli Avenue, 43025 Lutsk (Ukraine); Karpets, M.V. [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky Street, 03142 Kyiv (Ukraine); Parasyuk, O.V. [Department of Inorganic and Physical Chemistry, Lesya Ukrainka Eastern European National University, 13 Voli Avenue, 43025 Lutsk (Ukraine)

2016-10-15

Single crystal of the ternary halide Tl{sub 10}Hg{sub 3}Cl{sub 16} was grown using Bridgman-Stockbarger method. For the Tl{sub 10}Hg{sub 3}Cl{sub 16} crystal, we have measured X-ray photoelectron spectra for both pristine and Ar{sup +} ion-bombarded surfaces and additionally investigated photoinduced piezoelectricity. Our data indicate that the Tl{sub 10}Hg{sub 3}Cl{sub 16} single crystal surface is very sensitive with respect to Ar{sup +} ion-bombardment. In particular, Ar{sup +} ion-bombardment with energy of 3.0 keV over 5 min at an ion current density of 14 μA/cm{sup 2} causes significant changes of the elemental stoichiometry of the Tl{sub 10}Hg{sub 3}Cl{sub 16} surface resulting in an abrupt decrease of the mercury content in the top surface layers of the studied single crystal. As a result of the treatment, the mercury content becomes nil in the top surface layers. In addition, the present XPS measurements allow for concluding about very low hygroscopicity of the Tl{sub 10}Hg{sub 3}Cl{sub 16} single crystal surface. The property is extremely important for the crystal handling in optoelectronic or nano-electronic devices working at ambient conditions. The photoinduced piezoelectricity has been explored for Tl{sub 10}Hg{sub 3}Cl{sub 16} depending on nitrogen (λ=371 nm) laser power density and temperature. - Graphical abstract: As-grown single crystal boule of Tl{sub 10}Hg{sub 3}Cl{sub 16}; dependence of the effective piezoelecric coefficient d{sub 33} versus the photoinducing nitrogen laser power density, I, at different temperatures, T; and packing of the polyhedra of halide atoms around Hg atoms in the Tl{sub 10}Hg{sub 3}Cl{sub 16} structure. - Highlights: • High-quality Tl{sub 10}Hg{sub 3}Cl{sub 16} single crystal has been grown by Bridgman-Stockbarger method. • Electronic structure of Tl{sub 10}Hg{sub 3}Cl{sub 16} is studied by the XPS method. • Tl{sub 10}Hg{sub 3}Cl{sub 16} single crystal surface is sensitive with respect to Ar{sup +} ion

Temperature induced Spin Switching in SmFeO3 Single Crystal

Science.gov (United States)

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

2014-08-01

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

Properties of single crystal beta''-aluminas

International Nuclear Information System (INIS)

Bates, J.B.; Brown, G.M.; Kaneda, T.; Brundage, W.E.; Wang, J.C.; Engstrom, H.

1979-01-01

Large single crystals of sodium beta''-alumina were grown by slow evaporation of Na 2 O at 1690 0 C from a mixture of Na 2 CO 3 , MgO, and Al 2 O 3 . Polarized Raman measurements were made on the Na β'' single crystals and on single crystals of Li, K, Rb, and Ag β'' prepared by ion exchange of Na β''. The low frequency Raman spectra of Na, K, Rb, and Ag β'' contained four or more bands due to vibrations of the mobile cations. These results were analyzed by assuming the spectra to be due to the normal modes of a defect cluster consisting of a cation vacancy surrounded by three cations. From model calculations, the Raman band of Na β'' at 33 cm -1 is assigned to the attempt mode for diffusion of Na + ions. The structure of a Ag β'' single crystal was investigated by neutron diffraction, and 20% of the Ag + ion sites were found to be vacant

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.

Growth and characterization of lead-free (K,Na)NbO{sub 3}-based piezoelectric single crystals

Energy Technology Data Exchange (ETDEWEB)

Liu, Hairui

2016-10-19

Lead-free piezoelectric materials have received increasing attention in the last decade, driven by environmental issues and health concerns. Of considerable interest is the (K,Na)NbO{sub 3} (KNN)-based system, which possesses a relatively high Curie temperature and good piezoelectric properties. Abundant publications on KNN-based polycrystalline ceramics increased the interest in studying their single-crystalline form, based on two major concerns. The first concern refers to the negative role of grain interactions on the electromechanical response. The second concern deals with domain engineering. The relationship between external electric field direction, crystallographic orientation, and spontaneous polarization vectors for a specific structure can be more readily established in single crystals and thus offers a pathway for an in-depth understanding of fundamental mechanism and potential applications. The exciting enhancement of both piezoelectric and ferroelectric response in lead-based single crystals also encourages the further exploration of KNN-based piezoelectric crystals, as they possess the same perovskite structure. The main goal of this thesis is to find possible approaches for improved electromechanical properties in KNN-based piezoelectric single crystals. In Chapter 2, the current development of KNN-based single crystals as piezoelectrics is reviewed, following a short introduction of fundamental knowledge on piezoelectrics and ferroelectrics. Both submerged-seed solution growth and top-seeded solution growth techniques were employed to produce single crystals, as described detailed in Chapter 3. Emphasis is subsequently placed on issues of the crystal growth process, effective methods to enhance electrical properties, and crystallographic orientation-dependent electrical properties in Li-, Ta-, and/or Sb-substituted KNN single crystals. The main conclusions from the crystal growth aspect are presented in Chapter 4 and can be summarized as follows

Thickness-dependent photovoltaic effects in miscut Nb-doped SrTiO3 single crystals

International Nuclear Information System (INIS)

Yue Zengji; Zhao Kun; Zhao Songqing; Lu Zhiqing; Li Xiaoming; Ni Hao; Wang Aijun

2010-01-01

The photovoltaic effects of Nb-doped SrTiO 3 single crystals with different thicknesses were investigated under the illumination of ultraviolet pulsed lasers. The peak photovoltage increased and then decreased quickly with the decrease in crystal thickness, and a maximum photovoltage occurred for the 180 μm-thick crystal. The photovoltaic response time decreased monotonically with decreasing crystal thickness. The present results suggested the promising potential of reducing crystal thickness in high sensitivity detectors with fast response.

Determination of temperature-dependent thermal conductivity of a BaSnO{sub 3−δ} single crystal by using the 3ω method

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyung Joon; Kim, Tai Hoon; Lee, Woong-Jhae; Chai, Yisheng; Kim, Jae Wook; Jwa, Yeon Jae; Chung, Sukhwan; Kim, Seon Joong; Sohn, Egon [Center for Novel States of Complex Materials Research, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Lee, Seung Min [Hanbeam Corporation Ltd, Iui-dong 906-5, Yeongtong-gu, Suwon-si, Gyeonggi-do (Korea, Republic of); Choi, Ki-Young [Center for Novel States of Complex Materials Research, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Kim, Kee Hoon, E-mail: khkim@phya.snu.ac.kr [Center for Novel States of Complex Materials Research, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

2014-06-01

Highlights: • This is the first report about thermal conductivity of BaSnO{sub 3−δ} single crystals. • We report the successful κ measurement of the crystals by employing the 3ω method. • The BaSnO{sub 3−δ} single crystal can be a good perovskite substrate with high κ. • We found that phonons mainly contribute to the heat transport in BaSnO{sub 3−δ}. - Abstract: The single crystal of the electron doped BaSnO{sub 3−δ} system has been recently found to have high electrical mobility (up to 320 cm{sup 2} V{sup −1} s{sup −1}) at room temperature and excellent oxygen stability. Although thermal conductivity (κ) of the BaSnO{sub 3−δ} single crystal is an important physical quantity, the κ measurement by the conventional DC method has been difficult due to the limited crystal size. Herein, we report the first measurement of κ by using the 3ω method from ∼20 to 300 K in the oxygen deficient BaSnO{sub 3−δ} single crystal with carrier concentration of ∼10{sup 18} cm{sup −3}. We found that κ is proportional to T{sup −1} above 50 K, indicating that phonons mainly contribute to the heat transport. Moreover, the electronic contribution is determined as ∼4% of the measured κ from the Wiedemann–Franz law. The κ value is 0.132 W cm{sup −1} K{sup −1} at room temperature and is increased progressively at lower temperatures, becoming overall larger than that of the SrTiO{sub 3} single crystal. Our results thus point out that BaSnO{sub 3−δ} can be a good substrate for growing transparent electronic thin films with the perovskite structure.

Anisotropic and excellent magnetocaloric properties of La0.7Ca0.3MnO3 single crystal with anomalous magnetization

International Nuclear Information System (INIS)

Debnath, J.C.; Zeng, R.; Kim, J.H.; Chen, D.P.; Dou, S.X.

2012-01-01

Highlights: ► ΔS M shows a very large reversibility value at low field. ► The single crystal exhibits anisotropy in the MCE. ► La 0.7 Ca 0.3 MnO 3 is weakly itinerant ferromagnetic. ► No hysteresis loss is observed. - Abstract: Magnetic properties and the magnetocaloric effect (MCE) have been investigated in La 0.7 Ca 0.3 MnO 3 single crystal with applied field along both the ab-plane and the c-direction. Due to the magnetocrystalline anisotropy, the crystal exhibits anisotropy in the MCE. Upon application of a 5 T field, the magnetic entropy changes (ΔS M ), reaching values of 7.668 J/(kg K) and 6.412 J/(kg K) for both the ab-plane and the c-direction, respectively. A magnetic entropy change of 3.3 J/(kg K) was achieved for a magnetic field change of 1.5 T at the Curie temperature, T C = 245 K. Due to the absence of grains in the single crystal, the ΔS M distribution here is much more uniform than for gadolinium (Gd) and other polycrystalline manganites, which is desirable for an Ericsson-cycle magnetic refrigerator. For a field change of 5 T, the relative cooling power, RCP, reached 358.17 J/kg, while the maximum adiabatic temperature change of 5.33 K and a magnetoresistance (MR) ratio of 507.88% at T C were observed. We analysed the magnetization of La 0.7 Ca 0.3 MnO 3 single crystal at T C and estimated several parameters of spin fluctuation on the basis of a self-consistent renormalization theory of spin fluctuations, with reciprocal susceptibility above T C . We found that the magnetic property of La 0.7 Ca 0.3 MnO 3 is weakly itinerant ferromagnetic. A large reversible MCE and no hysteresis loss with a considerable value of refrigerant capacity indicate that La 0.7 Ca 0.3 MnO 3 single crystal is a potential candidate as a magnetic refrigerant.

Single-crystal growth of ceria-based materials

International Nuclear Information System (INIS)

Ulbrich, Gregor

2015-01-01

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.

Single crystal growth and characterization of kagomé-lattice shandites Co3Sn2-xInxS2

Science.gov (United States)

Kassem, Mohamed A.; Tabata, Yoshikazu; Waki, Takeshi; Nakamura, Hiroyuki

2015-09-01

Single crystals of the shandite-type half metallic ferromagnet Co3Sn2S2, and its In-substituted compounds, Co3Sn2-xInxS2 (0crystals. Single crystals of the two end members, Co3Sn2S2 and Co3In2S2, and solid solutions with low In concentrations (x≤0.35) were grown out of Sn and In self flux. Solid solution single crystals with higher In concentrations were grown out of Sn, In and Pb mixture flux. Grown crystals were characterized using the powder x-ray diffraction, wavelength-dispersive x-ray spectroscopy and magnetization measurements. The shandite structure with R3¯m symmetry was confirmed and crystal structure parameters of the obtained plate-shaped hexagonal crystals were refined using the Rietveld analysis. Magnetization measurements show suppression of the ferromagnetic ordering, observed in Co3Sn2S2, by In-substitution as reported for polycrystalline samples. The obtained crystals are useful to study anisotropy in magnetic and transport properties and further interesting magnetotransport properties of the layered compounds.

Paramagnetic resonance of LaGaO3: Mn single crystals grown by floating zone melting

Science.gov (United States)

Vazhenin, V. A.; Potapov, A. P.; Artyomov, M. Yu.; Salosin, M. A.; Fokin, A. V.; Gil'mutdinov, I. F.; Mukhamedshin, I. R.

2016-02-01

The EPR spectrum of Mn-doped lanthanum gallate single crystals grown by floating zone melting with optical heating has been studied. In contrast to the crystals grown according to the Czochralski method, no manganese is found in these crystals even after high-temperature annealing in air. The spectral characteristics of Fe3+ and Gd3+ centers in crystals prepared by various methods have been compared in the rhombohedral phase, and the fourth-rank nondiagonal parameters of the Fe3+ trigonal centers have been determined, as well.

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

KAUST Repository

Saidaminov, Makhsud I.

2015-07-06

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

Single crystal growth and nonlinear optical properties of Nd3+ doped STGS crystal for self-frequency-doubling application

Science.gov (United States)

Chen, Feifei; Wang, Lijuan; Wang, Xinle; Cheng, Xiufeng; Yu, Fapeng; Wang, Zhengping; Zhao, Xian

2017-11-01

The self-frequency-doubling crystal is an important kind of multi-functional crystal materials. In this work, Nd3+ doped Sr3TaGa3Si2O14 (Nd:STGS) single crystals were successfully grown by using Czochralski pulling method, in addition, the nonlinear and laser-frequency-doubling properties of Nd:STGS crystals were studied. The continuous-wave laser at 1064 nm was demonstrated along different physical axes, where the maximum output power was obtained to be 295 mW for the Z-cut samples, much higher than the Y-cut (242 mW) and X-cut (217 mW) samples. Based on the measured refractive indexes, the phase matching directions were discussed and determined for type I (42.5°, 30°) and type II (69.5°, 0°) crystal cuts. As expected, self-frequency-doubling green laser at 529 nm was achieved with output powers being around 16 mW and 12 mW for type I and type II configurations, respectively.

Synthesis of Mesoporous Single Crystal Co(OH)2 Nanoplate and Its Topotactic Conversion to Dual-Pore Mesoporous Single Crystal Co3O4.

Science.gov (United States)

Jia, Bao-Rui; Qin, Ming-Li; Li, Shu-Mei; Zhang, Zi-Li; Lu, Hui-Feng; Chen, Peng-Qi; Wu, Hao-Yang; Lu, Xin; Zhang, Lin; Qu, Xuan-Hui

2016-06-22

A new class of mesoporous single crystalline (MSC) material, Co(OH)2 nanoplates, is synthesized by a soft template method, and it is topotactically converted to dual-pore MSC Co3O4. Most mesoporous materials derived from the soft template method are reported to be amorphous or polycrystallined; however, in our synthesis, Co(OH)2 seeds grow to form single crystals, with amphiphilic block copolymer F127 colloids as the pore producer. The single-crystalline nature of material can be kept during the conversion from Co(OH)2 to Co3O4, and special dual-pore MSC Co3O4 nanoplates can be obtained. As the anode of lithium-ion batteries, such dual-pore MSC Co3O4 nanoplates possess exceedingly high capacity as well as long cyclic performance (730 mAh g(-1) at 1 A g(-1) after the 350th cycle). The superior performance is because of the unique hierarchical mesoporous structure, which could significantly improve Li(+) diffusion kinetics, and the exposed highly active (111) crystal planes are in favor of the conversion reaction in the charge/discharge cycles.

Pyroelectric Study on Dipolar Alignment in 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 Single Crystals

Institute of Scientific and Technical Information of China (English)

ZHAO Liang; SHEN Ming-Rong; CAO Wen-Wu

2012-01-01

Pyroelectric measurements are conducted during zero-Geld heating in [001], [110] and [111] poled 0.69Pb(Mg1/3 Nb2/3)O3-0.31PbTiO3 single crystals. Compared to the room-temperature-poled samples, the crystals poled by using the Rield cooling method show broad but well recognizable pyroelectric current peaks near 190℃, which is much higher than the Curie point (126℃) of the crystal. We propose that this peak of the crystals poled by field-cooling above the Curie point is ascribed to the order-disorder transition of the dipoles in polar nano-regions formed at the Burns temperature.%Pyroelectric measurements are conducted during zero-field heating in [001],[110] and [111] poled 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 single crystals.Compared to the room-temperature-poled samples,the crystals poled by using the field cooling method show broad but well recognizable pyroelectric current peaks near 190℃,which is much higher than the Curie point (126℃) of the crystal.We propose that this peak of the crystals poled by field-cooling above the Curie point is ascribed to the order-disorder transition of the dipoles in polar nano-regions formed at the Burns temperature.

Raman selection rules and tensor elements for PMN-0.3PT single crystal

International Nuclear Information System (INIS)

Ge, Wanyin; Zhu, Wenliang; Pezzotti, Giuseppe

2009-01-01

Selection rules were put forward theoretically and Raman tensor elements experimentally determined for PMN-0.3PT single-crystal. Such a body of information was then employed to evaluate local domain orientation in a relaxor-based PMN-0.3PT material by means of polarized microprobe Raman spectroscopy. The dependence of Raman spectra upon crystal rotation under different polarized probe configurations was experimentally confirmed by collecting the intensity variation of selected Raman modes on Euler's angle rotation in a poled single-crystal. The periodicity of relative Raman intensity of selected Raman bands revealed symmetry properties. Upon exploiting such properties and with the knowledge of the Raman tensor elements from the A g and E g vibrational modes, a viable path becomes available to determine domain texture in relaxor-based PMN-PT materials with high spatial resolution. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Growth and electrical properties of (Mn,F) co-doped 0.92Pb(Zn 1/3Nb 2/3)O 3-0.08PbTiO 3 single crystal

Science.gov (United States)

Zhang, Shujun; Lebrun, Laurent; Randall, Clive A.; Shrout, Thomas R.

2004-06-01

The growth and characterization of (Mn,F) doped Pb(Zn 1/3Nb 2/3)O 3-PbTiO 3 (PZNT) single crystals are reported in this paper. The typical single crystal obtained is up to 30 mm size with dark brown color. The crystal lattice parameters of doped PZNT crystal are slightly decreased compared to the pure one. The room temperature dielectric permittivity along direction is about 6000, which is lower than that of the pure PZNT8 because of the dopants. The Curie temperature of the doped crystal is about 180°C while the ferroelectric phase transition temperature is around 100°C, which are higher than those of the pure PZNT8 single crystal. The remnant polarization and coercive field of oriented doped crystal measured at 1 Hz and 10 kV/cm field are about 27 μC/cm 2 and 4.2 kV/cm, respectively. The room temperature mechanical quality factor is ˜300. Piezoelectric coefficient of oriented doped crystal is higher than 3500 pC/N and the longitudinal electromechanical coupling factor is larger than 93%. The piezoelectric properties of doped PZNT single crystal with temperature and orientations are also reported in this paper. The valence state of the manganese dopant was determined by electron spin resonance, indicating no Mn 4+ in the crystals, suggesting the valence of manganese ions in PZNT crystals may be 2+, which acts as a hardener, stabilizes the domain wall and pins the domain wall motion, on the other hand, the dopant will enter Ti 4+ position, shifting the crystal composition to higher PT content.

Inhomogeneous ferrimagnetic-like behavior in Gd2/3Ca1/3MnO3 single crystals

International Nuclear Information System (INIS)

Haberkorn, N.; Larregola, S.; Franco, D.; Nieva, G.

2009-01-01

We present a study of the magnetic properties of Gd 2/3 Ca 1/3 MnO 3 single crystals at low temperatures, showing that this material behaves as an inhomogeneous ferrimagnet. In addition to small saturation magnetization at 5 K, we have found history dependent effects in the magnetization and the presence of exchange bias. These features are compatible with microscopic phase separation in the clean Gd 2/3 Ca 1/3 MnO 3 system studied

Growth from the melt of high-quality In2O3 and Ga2O3 single crystals

Energy Technology Data Exchange (ETDEWEB)

Fornari, Roberto; Galazka, Zbigniew; Uecker, Reinhard; Irmscher, Klaus [Leibniz Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin (Germany)

2013-07-01

Because of their interesting properties semiconducting oxides, in particular Ga{sub 2}O{sub 3} In{sub 2}O{sub 3}, have recently received much attention. However, as they were deposited as films on hetero-substrates their quality was quite poor. The growth of high-quality bulk Ga{sub 2}O{sub 3} and In{sub 2}O{sub 3} and manufacture of the corresponding substrates can allow the deposition of high-quality epilayers with lower residual carrier density and fewer extended defects. For this reason IKZ has undertaken an effort to grow large single crystals of these oxide compounds from the melt. Transparent semiconducting Ga{sub 2}O{sub 3} single crystals with diameter of about 20 mm and 50-60 mm long were grown by the Czochralski method along the b-axis, using an Iridium crucible and a dynamic protective atmosphere to minimize the dissociation of Ga{sub 2}O{sub 3} melt and ingot. In the case of In{sub 2}O{sub 3} the Czochralski technique is not applicable and it was necessary to develop a novel melt growth method. This new method indeed supplied crystals from which oriented substrates could be prepared. In this presentation the melt growth of Ga{sub 2}O{sub 3} and In{sub 2}O{sub 3} single crystals will be reviewed. An important feature of both materials is given by their strong sensitivity to thermal processing: the free carrier concentration and the absorption spectra drastically vary as a function of annealing temperature, duration and ambient. The possible causes are discussed.

Modulated magnetic structure of an inhomogeneous stressed single crystal FeBO3

International Nuclear Information System (INIS)

Sharipiv, M.Z.; Dzhuraev, D.R.; Sokolov, B.Yu.; Kurbanov, M.

2010-01-01

With the help of low-symmetry mechanical stresses, we induced an additional spatially inhomogeneous anisotropy in the basal plane of a single crystal FeBO 3 . By the magnetooptical method, we study the effect of an inhomogeneous magnetic anisotropy on the magnetic state of this easy-plane weak ferromagnetic. It is established that, at the magnetization of inhomogeneously stressed FeBO 3 in the basal plane near some separated direction, the crystal transits from the homogeneous state into a spatially modulated magnetic state. The latter can be represented in the form of a static spin wave, in which a local vector of ferromagnetism oscillates near the direction of the mean magnetization of a crystal, by remaining in the basal plane.

Growth of single crystals of BaFe12O19 by solid state crystal growth

International Nuclear Information System (INIS)

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

2016-01-01

Single crystals of BaFe 12 O 19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe 12 O 19 are buried in BaFe 12 O 19 +1 wt% BaCO 3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe 12 O 19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe 12 O 19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth. - Highlights: • Single crystals of BaFe 12 O 19 are grown by solid state crystal growth. • A single crystal up to ∼130 μm thick (c-axis direction) grows on the seed crystal. • The single crystal and surrounding ceramic matrix have similar composition. • Micro-Raman scattering shows the single crystal has the BaFe 12 O 19 structure.

Scintillation characteristics of LiB3O5 and β-BaB2O4 single crystals

International Nuclear Information System (INIS)

Nazarenko, B.P.; Pedash, V.Yu.; Shekhovtsov, A.N.; Tarasov, V.A.; Zelenskaya, O.V.

2006-01-01

LiB 3 O 5 and β-BaB 2 O 4 single crystals have been grown by the top seeded solution growth technique. The optical characteristics and scintillation parameters of the grown single crystals have been tested and discussed

Crystal growth and piezoelectric properties of Ca3Ta(Ga0.9Sc0.1)3Si2O14 bulk single crystal

Science.gov (United States)

Igarashi, Yu; Yokota, Yuui; Ohashi, Yuji; Inoue, Kenji; Yamaji, Akihiro; Shoji, Yasuhiro; Kamada, Kei; Kurosawa, Shunsuke; Yoshikawa, Akira

2018-03-01

Ca3Ta(Ga0.9Sc0.1)3Si2O14 langasite-type single crystal with a diameter of 1 in. was grown by Czochralski (Cz) method. Obtained crystal had good crystallinity and its lattice constants exceeded those of Ca3TaGa3Si2O14 (CTGS) according to the X-ray analysis. A crack-free specimen cut from the grown crystal was used for the measurements of dielectric constant ε11T/ε0, electromechanical coupling factor k12, and piezoelectric constant d11. The accuracies of these measurements were better than those for the crystal grown by micro-pulling-down (μ-PD) method. Substitution of Ga with Sc resulted modification of these constants in the directions opposite to those observed after partial substitution of Ga (of CTGS) with Al. This suggests that increase of |d14| was most probably associated with enlargement of average size of the Ga sites. The crystal reported here had greater dimensions as compared to analogous crystals grown by the μ-PD method. As a result, accuracy of determination of acoustic constants of this material may be improved.

single crystals

Indian Academy of Sciences (India)

2018-05-18

May 18, 2018 ... Abstract. 4-Nitrobenzoic acid (4-NBA) single crystals were studied for their linear and nonlinear optical ... studies on the proper growth, linear and nonlinear optical ..... between the optic axes and optic sign of the biaxial crystal.

Single crystal growth, characterization and high-pressure Raman spectroscopy of impurity-free magnesite (MgCO3)

Science.gov (United States)

Liang, Wen; Li, Zeming; Yin, Yuan; Li, Rui; Chen, Lin; He, Yu; Dong, Haini; Dai, Lidong; Li, Heping

2018-05-01

The understanding of the physical and chemical properties of magnesite (MgCO3) under deep-mantle conditions is highly important to capture the essence of deep-carbon storage in Earth's interior. To develop standard rating scales, the impurity-free magnesite single crystal, paying particular attention to the case of avoiding adverse impacts of Ca2+, Fe2+, and Mn2+ impurities in natural magnesite, is undoubtedly necessary for all research of magnesite, including crystalline structural phase transitions, anisotropic elasticity and conductivity, and equation of state (EoS). Thus, a high-quality single crystal of impurity-free magnesite was grown successfully for the first time using the self-flux method under high pressure-temperature conditions. The size of the magnesite single crystal, observed in a plane-polarized microscope, exceeds 200 μm, and the crystal exhibits a rhombohedral structure to cleave along the (101) plane. In addition, its composition of Mg0.999 ± 0.001CO3 was quantified through electron probing analysis. The structural property was investigated by means of single crystal X-ray diffraction and the unit cell dimensions obtained in the rhombohedral symmetry of the R\\bar {3}c space group are a = 4.6255 (3) and c = 14.987 (2), and the final R = 0.0243 for 718 reflections. High-pressure Raman spectroscopy of the magnesite single crystal was performed up to 27 GPa at ambient temperature. All Raman active bands, ν i, without any splitting increased almost linearly with increasing pressure. In combination with the high-pressure Raman results {{d/ν _i}}{{{d}P}} and the bulk modulus K T (103 GPa) reported from magnesite EoS studies, the mode Grüneisen parameters (1.49, 1.40, 0.26, and 0.27) of each vibration ( T, L, ν 4, and ν 1) were calculated.

Photoluminescence and lasing properties of MAPbBr3 single crystals grown from solution

Science.gov (United States)

Aryal, Sandip; Lafalce, Evan; Zhang, Chuang; Zhai, Yaxin; Vardeny, Z. Valy

Recent studies of solution-grown single crystals of inorganic-organic hybrid lead-trihalide perovskites have suggested that surface traps may play a significant role in their photophysics. We study electron-hole recombination in single crystal MAPbBr3 through such trap states using cw photoluminescence (PL) and ps transient photoinduced absorption (PA) spectroscopies. By varying the depth of the collecting optics we examined the contributions from surface and bulk radiative recombination. We found a surface dominated PL band at the band-edge that is similar to that observed from polycrystalline thin films, as well as a weaker red-shifted emission band that originates from the bulk crystal. The two PL bands are distinguished in their temperature, excitation intensity and polarization dependencies, as well as their ps dynamics. Additionally, amplified spontaneous emission and crystal-related cavity lasing modes were observed in the same spectral range as the PL band assigned to the surface recombination. This work was funded by AFOSR through MURI Grant RA 9550-14-1-0037.

Optical and electrical properties of ZrSe3 single crystals grown by chemical vapour transport technique

International Nuclear Information System (INIS)

Patel, Kaushik; Prajapati, Jagdish; Vaidya, Rajiv; Patel, S.G.

2005-01-01

Single crystals of the lamellar compound, ZrSe 3 , were grown by chemical vapour transport technique using iodine as a transporting agent. The grown crystals were characterized with the help of energy dispersive analysis by X-ray (EDAX), which gave confirmation about the stoichiometry. The optical band gap measurement of as grown crystals was carried out with the help of optical absorption spectra in the range 700-1450 nm. The indirect as well as direct band gap of ZrSe 3 were found to be 1.1 eV and 1.47 eV, respectively. The resistivity of the as grown crystals was measured using van der Pauw method. The Hall parameters of the grown crystals were determined at room temperature from Hall effect measurements. Electrical resistivity measurements were performed on this crystal in the temperature range 303-423 K. The crystals were found to exhibit semiconducting nature in this range. The activation energy and anisotropy measurements were carried out for this crystal. Pressure dependence of electrical resistance was studied using Bridgman opposed anvils set up up to 8 GPa. The semiconducting nature of ZrSe 3 single crystal was inferred from the graph of resistance vs pressure. The results obtained are discussed in detail. (author)

Single crystals of the anisotropic Kagome staircase compounds Ni3V2O8 and Co3V2O8

OpenAIRE

Balakrishnan, G.; Petrenko, O. A.; Lees, M. R.; Paul, D. McK.

2004-01-01

Compounds with a Kagome type lattice are known to exhibit magnetic frustration. Large single crystals of two compounds Ni3V2O8 and Co3V2O8, which are variants of a Kagome net lattice, have been grown successfully by the floating zone technique using an optical image furnace. The single crystals are of high quality and exhibit intriguing magnetic properties.

Optical energy gaps and photoluminescence peaks of BaGa2S4:Er3+ and BaGa2Se4:Er3+ single crystals

International Nuclear Information System (INIS)

Choe, Sung-Hyu; Jin, Moon-Seog; Kim, Wha-Tek

2005-01-01

BaGa 2 S 4 :Er 3+ and BaGa 2 Se 4 :Er 3+ single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the BaGa 2 S 4 :Er 3+ and the BaGa 2 Se 4 :Er 3+ single crystals were found to be 4.045 eV and 3.073 eV, respectively, at 11 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Sharp emission peaks were observed in the photoluminescence spectra of the single crystals and assigned to radiation recombination between split Stark levels of the Er 3+ ion.

Growth of Yb3+-doped Y2O3 single crystal rods by the micro-pulling-down method

International Nuclear Information System (INIS)

Mun, J.H.; Novoselov, A.; Yoshikawa, A.; Boulon, G.; Fukuda, T.

2005-01-01

The rare-earth sesquioxides (RE 2 O 3 , RE = Lu, Y and Sc) are very promising host crystals for advanced laser diode (LD)-pumped Yb 3+ -doped solid-state lasers due to unusual combination, almost unique of favourable structural, thermal and spectroscopic properties which are described. In spite of these favourable properties, the bulk single crystal growth technology for the rare-earth sesquioxides has not been established yet. The extremely high melting temperature at around 2400 deg. C has prevented it. However, we shall show that yttrium oxide crystals (Yb x Y 1-x ) 2 O 3 , x = 0.0, 0.005, 0.05, 0.08 and 0.15 of cylindrical shape as laser rods with 4.2 mm in diameter and 15-20 mm in length have been grown from rhenium crucibles by the micro-pulling-down method. The crystal quality characterisation of undoped Y 2 O 3 crystal was determined using X-ray rocking curve (XRC) analysis. Yb were homogeneously distributed in Y 2 O 3 host crystal

Magnetic, transport, and optical properties of Ca0.85Eu0.15MnO3 single crystal

International Nuclear Information System (INIS)

Naumov, S.V.; Loshkareva, N.N.; Mostovshchikova, E.V.; Solin, N.I.; Korolev, A.V.; Arbuzova, T.I.; Telegin, S.V.; Patrakov, E.I.

2013-01-01

Magnetic, transport and optical properties of the Ca 0.85 Eu 0.15 MnO 3 single crystal are studied and discussed in comparison with the properties of polycrystalline sample. The magnetic data show existence the two magnetic phase transitions under cooling: the transition near 150 K occurs from the paramagnetic orthorhombic to C-type antiferromagnetic monoclinic phase with the charge/orbital ordering in some part of the crystal; and at 90 K the transition from the paramagnetic to G-type antiferromagnetic phase takes place in another part of the crystal with the orthorhombic structure. The magnetoresistance of the Ca 0.85 Eu 0.15 MnO 3 single crystal has features at temperatures of these phase transitions. Differences in the properties of single crystal and polycrystalline sample with the same content of Eu are associated with the ordering of oxygen vacancies that appear under the crystal growth. The reflection spectra in infrared range confirm the existence of the electron conductivity in a narrow band at room temperature.

Electrically Anisotropic Layered Perovskite Single Crystal

KAUST Repository

Li, Ting-You

2016-04-01

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

The spectroscopy investigation of ZnWO{sub 4}:Tm{sup 3+} single crystal

Energy Technology Data Exchange (ETDEWEB)

Yang Fugui, E-mail: ruopiao@fjirsm.ac.cn [Department of Electronic Information Science, Fujian Jiangxia University, Fuzhou, Fujian 350108 (China); Tu Chaoyang [Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

2012-09-15

Highlights: Black-Right-Pointing-Pointer The spectroscopy and refractive index of single crystal ZnWO{sub 4}:Tm{sup 3+} are investigated systematically. Black-Right-Pointing-Pointer The Judd-Ofelt parameters are obtained. Black-Right-Pointing-Pointer The gain cross sections at {approx}2 {mu}m are estimated by reciprocity method (RM). Black-Right-Pointing-Pointer The laser operation at {approx}2 {mu}m is discussed. - Abstract: The single crystal ZnWO{sub 4}:Tm{sup 3+} has been grown by Czochralski method. The XRD, refractive index, absorption and fluorescence spectra are measured. The Judd-Ofelt parameters{Omega}{sub 2}, {Omega}{sub 4}, {Omega}{sub 6} are obtained to be 6.3 Multiplication-Sign 10{sup -20}, 1.3 Multiplication-Sign 10{sup -20}, 1.4 Multiplication-Sign 10{sup -20} cm{sup 2}, respectively. The fluorescence decay time of the {sup 3}H{sub 4} level is measured to be 0.113 ms and the quantum efficiency is 57%. The gain cross sections corresponding to {sup 3}F{sub 4}{yields}{sup 3}H{sub 6} transition at {approx}2 {mu}m are estimated by the reciprocity method (RM). The strong gain at {approx}2 {mu}m indicates that the ZnWO{sub 4}:Tm{sup 3+} crystal is a promising laser host for {approx}2 {mu}m laser.

Scintillation and optical properties of Ce{sup 3+}-doped CaGdAl{sub 3}O{sub 7} single crystals

Energy Technology Data Exchange (ETDEWEB)

Mori, Masaki, E-mail: masaki.mori.mz4@ms.naist.jp [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama-cho, Ikoma-shi, Nara 630-0192 (Japan); Nakauchi, Daisuke; Okada, Go [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama-cho, Ikoma-shi, Nara 630-0192 (Japan); Fujimoto, Yutaka [Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai, 980-8579 (Japan); Kawaguchi, Noriaki [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama-cho, Ikoma-shi, Nara 630-0192 (Japan); Koshimizu, Masanori [Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai, 980-8579 (Japan); Yanagida, Takayuki [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama-cho, Ikoma-shi, Nara 630-0192 (Japan)

2017-06-15

The single crystals of 0, 0.6, 1, 1.6 and 2 mol% Ce doped CaGdAl{sub 3}O{sub 7} (Ce:CGAM) were grown by the Floating Zone method, and investigated on photoluminescence (PL) and scintillation properties. In the PL spectra, a broad emission appeared over 380–500 nm under 280 and 360 nm excitations with the quantum yield of 33.8–38.8%. Under a vacuum ultraviolet excitation (90 nm) using a synchrotron source, non-doped CGAM single crystal showed broad emissions over 250–650 nm. The PL decay time profiles followed a monotonic exponential decay with a decay time constant of around 33 ns. The scintillation spectra were similar to those of PL. All of the samples exhibited a clear photoabsorption peak and Compton edge in the pulse height spectra measured under {sup 137}Cs γ-ray irradiation, and the absolute scintillation light yield (LY) was highest for the 2% Ce-doped sample with the value of 3300±300 ph/MeV. The scintillation decay profiles were approximated by a third order exponential decay function, and the extracted decay time of Ce{sup 3+} emission component was around 36–44 ns. Among all the samples, 2%Ce:CGAM single crystal sample showed the best afterglow level as a scintillator under X-ray irradiation. - Highlights: •Ce{sup 3+}-doped CaGdAl{sub 3}O{sub 7} single crystals were synthesized by the FZ method. •Optical and scintillation properties of Ce{sup 3+}-doped CaGdAl{sub 3}O{sub 7} were investigated. •Photoabsorption peak in a pulse height spectrum was clearly observed under γ-rays.

Growth of single crystals of BaFe12O19 by solid state crystal growth

Science.gov (United States)

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

2016-10-01

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

Growth and luminescent properties of Yb3+--doped oxide single crystals for scintillator application

International Nuclear Information System (INIS)

Yoshikawa, A.; Ogino, H.; Shim, J.B.; Nikl, M.; Solovieva, N.; Fukuda, T.

2004-01-01

Rod-shaped (Lu 1-x Yb x ) 3 Al 5 O 12 with x=0.05, 0.15, 0.30 and (Y 1-x Yb x )AlO 3 with x=0.05, 0.10, 0.30 single crystals were grown by the micro-pulling-down method. Edge-defined film-fed growth method was used to prepare (Y 0.9 Yb 0.1 )VO 4 crystal, while Ca 8 (La 1.98 Yb 0.02 )(PO 4 ) 6 O 2 crystal was grown by the Czochralski method. Luminescence of these crystals was studied with main attention paid to the charge transfer emission of Yb 3+ . Temperature tuned decay times in the time scale of units--tens of nanosecond was measured as a feature possibly interesting for an application in scintillation detectors in positron emission tomography

The new single crystal diffractometer SC3

International Nuclear Information System (INIS)

Schefer, J.; Koch, M.; Keller, P.; Fischer, S.; Thut, R.

1996-01-01

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

The new single crystal diffractometer SC3

Energy Technology Data Exchange (ETDEWEB)

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

1996-11-01

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

Crystal growth, spectral and laser properties of Nd:LSAT single crystal

Science.gov (United States)

Hu, P. C.; Yin, J. G.; Zhao, C. C.; Gong, J.; He, X. M.; Zhang, L. H.; Liang, X. Y.; Hang, Y.

2011-10-01

Nd:(La, Sr)(Al, Ta)O3 (Nd:LSAT) crystal was grown by the Czochralski method. The absorption and fluorescence spectra of Nd:LSAT crystal at room temperature were investigated. With a fiber-coupled diode laser as pump source, the continuous-wave (CW) laser action of Nd:LSAT crystal was demonstrated. The result of diode-pumped laser operation of Nd:LSAT crystal single crystal is reported for what is to our knowledge the first time. The maximum output power at 1064 nm was obtained to be 165 mW under the incident pump power of 3 W, with the slope efficiency 10.9%.

Phase fragility and mechatronic reliability for Pb(Mg1/3Nb2/3O3–PbTiO3 ferroelectric single crystals — A review

Directory of Open Access Journals (Sweden)

F. Fang

2014-01-01

Full Text Available Single crystals of (1-xPb(Mg1/3Nb2/3O3–xPbTiO3(PMN–xPT near their morphotropic phase boundaries (MPBs are under extensive investigations for their extraordinary high dielectric and piezoelectric behavior. Applications of those single crystals facilitated the breakthrough in ultrasonic transducer materials and devices. Ferroelectric materials are known to be fragile which often leads to various reliability failures in applications involving electric loadings. In a mechanical sense, the failure modes concern the fracture under an intensive electric field, and the fatigue crack propagation under an alternating electric field. In an electrical sense, the failure is exhibited by degenerated hysteresis loop by shrinking the remnant polarization and expanding the coercive field. All these modes degrade the performance for ferroelectric devices. As a departure from the tetragonal (T ferroelectric materials, exemplified by BaTiO3 and Pb(ZrTiO3, the domain structures of PMN–PT around the MPB are versatile and intricate, depending sensitively on the composition variation, orientation and previous loading history. In this review, the attention is mainly focused on three aspects. First, the phase fragility and multiphase coexistence are presented for both [100]- and [101]-oriented PMN–PT single crystals. Second, investigations on electric field-induced fatigue crack propagation are described, along with the orientation effect on the crack propagation behavior. Third, the inverse effects of the phase transition and fatigue crack growth on the polarization behavior, or the interaction between the mechanical and electrical degradations will be elucidated. The review aims for better understanding the underlying mechanism for the ultrahigh performance of the PMN–PT single crystals, to bridge the studies of ferroelectric materials from the mechanical and electrical senses, as well as to evaluate the reliability of PMN–PT single crystals under device

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

KAUST Repository

Chao, Chunying

2012-08-15

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

Crystal structure investigations of ZrAsxSey (x>y, x+y≤2) by single crystal neutron diffraction at 300 K, 25 K and 2.3 K

International Nuclear Information System (INIS)

Niewa, Rainer; Czulucki, Andreas; Schmidt, Marcus; Auffermann, Gudrun; Cichorek, Tomasz; Meven, Martin; Pedersen, Bjoern; Steglich, Frank; Kniep, Ruediger

2010-01-01

Large single crystals of ZrAs x Se y (x>y, x+y≤2, PbFCl type of structure, space group P4/nmm) were grown by Chemical Transport. Structural details were studied by single crystal neutron diffraction techniques at various temperatures. One single crystal specimen with chemical composition ZrAs 1.595(3) Se 0.393(1) was studied at ambient temperature (R1=5.10 %, wR2=13.18 %), and a second crystal with composition ZrAs 1.420(3) Se 0.560(1) was investigated at 25 K (R1=2.70%, wR2=5.70 %) and 2.3 K (R1=2.30 %, wR2=4.70 %), respectively. The chemical compositions of the crystals under investigation were determined by wavelength dispersive X-ray spectroscopy. The quantification of trace elements was carried out by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry. According to the crystal structure refinements the crystallographic 2a site is occupied by As, together with a significant amount of vacancies. One of the 2c sites is fully occupied by As and Se (random distribution). With respect to the fractional coordinates of the atoms, the crystal structure determinations based on the data obtained at 25.0 K and 2.3 K did not show significant deviations from ambient temperature results. The temperature dependence of the displacement parameters indicates a static displacement of As on the 2a sites (located on the (0 0 1) planes) for all temperatures. No indications for any occupation of interstitial sites or the presence of vacancies on the Zr (2a) site were found. - Graphical abstract: Large single crystals of ZrAs x Se y grown by Chemical Transport to study structural details as the As-Se order scheme by single crystal neutron diffraction.

Single-crystal perovskite CH3NH3PbBr3 prepared by cast capping method for light-emitting diodes

Science.gov (United States)

Nguyen, Van-Cao; Katsuki, Hiroyuki; Sasaki, Fumio; Yanagi, Hisao

2018-04-01

In this study, electroluminescence from single crystals of CH3NH3PbBr3 perovskite is explored. The cast capping method was applied to fabricate simple devices with an ITO/CH3NH3PbBr3/ITO structure. The devices showed a low operation voltage of 2 V and a pure green luminescence with full width at half maximum of ∼20 nm. However, the emission occurring at the crystal edges demonstrated blinking with a subsecond time interval, which is similar to the previously reported photoluminescence behavior of nanocrystal perovskites. This electroluminescence blinking may provide new insight into the recombination processes depending on the carrier traps and defects of emission layers in perovskite light-emitting devices.

Solvent-induced controllable synthesis, single-crystal to single-crystal transformation and encapsulation of Alq3 for modulated luminescence in (4,8)-connected metal-organic frameworks.

Science.gov (United States)

Lan, Ya-Qian; Jiang, Hai-Long; Li, Shun-Li; Xu, Qiang

2012-07-16

In this work, for the first time, we have systematically demonstrated that solvent plays crucial roles in both controllable synthesis of metal-organic frameworks (MOFs) and their structural transformation process. With solvent as the only variable, five new MOFs with different structures have been constructed, in which one MOF undergoes solvent-induced single-crystal to single-crystal (SCSC) transformation that involves not only solvent exchange but also the cleavage and formation of coordination bonds. Particularly, a significant crystallographic change has been realized through an unprecedented three-step SCSC transformation process. Furthermore, we have demonstrated that the obtained MOF could be an excellent host for chromophores such as Alq3 for modulated luminescent properties.

Preparation of metastable bcc permalloy epitaxial thin films on GaAs(011)B3 single-crystal substrates

International Nuclear Information System (INIS)

Ohtake, Mitsuru; Higuchi, Jumpei; Yabuhara, Osamu; Kirino, Fumiyoshi; Futamoto, Masaaki

2011-01-01

Permalloy (Py) single-crystal films with bcc structure were obtained on GaAs(011) B3 single-crystal substrates by ultra high vacuum rf magnetron sputtering. The film growth and the detailed film structures were investigated by refection high energy electron diffraction and pole figure X-ray diffraction. bcc-Py films epitaxially grow on the substrates in the orientation relationship of Py(011)[011-bar] bcc || GaAs(011)[011-bar] B3 . The lattice constant of bcc-Py film is determined to be a = 0.291 nm. With increasing the film thickness, parts of the bcc crystal transform into more stable fcc structure by atomic displacement parallel to the bcc{011} close-packed planes. The resulting film thus consists of a mixture of bcc and fcc crystals. The phase transformation mechanism is discussed based on the experimental results. The in-plane magnetization properties reflecting the magnetocrystalline anisotropy of bcc-Py crystal are observed for the Py films grown on GaAs(011) B3 substrates.

Attenuation of thermal neutrons by an imperfect single crystal

Energy Technology Data Exchange (ETDEWEB)

Naguib, K.; Adib, M. [National Research Centre, Cairo (Egypt). Reactor and Neutron Physics Dept.

1996-06-14

A semi-empirical formula is given which allows one to calculate the total thermal cross section of an imperfect single crystal as a function of crystal constants, temperature and neutron energy E, in the energy range between 3 meV and 10 eV. The formula also includes the contribution of the parasitic Bragg scattering to the total cross section that takes into account the crystal mosaic spread value and its orientation with respect to the neutron beam direction. A computer program (ISCANF) was developed to calculate the total attenuation of neutrons using the proposed formula. The ISCANF program was applied to investigate the neutron attenuation through a copper single crystal. The calculated values of the neutron transmission through the imperfect copper single crystal were fitted to the measured ones in the energy range 3-40 meV at different crystal orientations. The result of fitting shows that use of the computer program ISCANF allows one to predict the behaviour of the total cross section of an imperfect copper single crystal for the whole energy range. (author).

Attenuation of thermal neutrons by an imperfect single crystal

Science.gov (United States)

Naguib, K.; Adib, M.

1996-06-01

A semi-empirical formula is given which allows one to calculate the total thermal cross section of an imperfect single crystal as a function of crystal constants, temperature and neutron energy E, in the energy range between 3 meV and 10 eV. The formula also includes the contribution of the parasitic Bragg scattering to the total cross section that takes into account the crystal mosaic spread value and its orientation with respect to the neutron beam direction. A computer program (ISCANF) was developed to calculate the total attenuation of neutrons using the proposed formula. The ISCANF program was applied to investigate the neutron attenuation through a copper single crystal. The calculated values of the neutron transmission through the imperfect copper single crystal were fitted to the measured ones in the energy range 3 - 40 meV at different crystal orientations. The result of fitting shows that use of the computer program ISCANF allows one to predict the behaviour of the total cross section of an imperfect copper single crystal for the whole energy range.

Ultra-fast scintillation properties of β-Ga2O3 single crystals grown by Floating Zone method

Science.gov (United States)

He, Nuotian; Tang, Huili; Liu, Bo; Zhu, Zhichao; Li, Qiu; Guo, Chao; Gu, Mu; Xu, Jun; Liu, Jinliang; Xu, Mengxuan; Chen, Liang; Ouyang, Xiaoping

2018-04-01

In this investigation, β-Ga2O3 single crystals were grown by the Floating Zone method. At room temperature, the X-ray excited emission spectrum includes ultraviolet and blue emission bands. The scintillation light output is comparable to the commercial BGO scintillator. The scintillation decay times are composed of the dominant ultra-fast component of 0.368 ns and a small amount of slightly slow components of 8.2 and 182 ns. Such fast component is superior to most commercial inorganic scintillators. In contrast to most semiconductor crystals prepared by solution method such as ZnO, β-Ga2O3 single crystals can be grown by traditional melt-growth method. Thus we can easily obtain large bulk crystals and mass production.

Regio-Regular Oligo and Poly(3-hexyl thiophene): Precise Structural Markers from the Vibrational Spectra of Oligomer Single Crystals.

KAUST Repository

Brambilla, Luigi; Tommasini, Matteo; Botiz, Ioan; Rahimi, Khosrow; Agumba, John O.; Stingelin, Natalie; Zerbi, Giuseppe

2014-01-01

, namely, amorphous, semicrystalline, polycrystalline and single crystal. We have based our analysis on the spectra of the (3HT)8 single crystal (whose structure has been determined by selected area electron diffraction) taken as reference

Principles of crystallization, and methods of single crystal growth

International Nuclear Information System (INIS)

Chacra, T.

2010-01-01

Most of single crystals (monocrystals), have distinguished optical, electrical, or magnetic properties, which make from single crystals, key elements in most of technical modern devices, as they may be used as lenses, Prisms, or grating sin optical devises, or Filters in X-Ray and spectrographic devices, or conductors and semiconductors in electronic, and computer industries. Furthermore, Single crystals are used in transducer devices. Moreover, they are indispensable elements in Laser and Maser emission technology.Crystal Growth Technology (CGT), has started, and developed in the international Universities and scientific institutions, aiming at some of single crystals, which may have significant properties and industrial applications, that can attract the attention of international crystal growth centers, to adopt the industrial production and marketing of such crystals. Unfortunately, Arab universities generally, and Syrian universities specifically, do not give even the minimum interest, to this field of Science.The purpose of this work is to attract the attention of Crystallographers, Physicists and Chemists in the Arab universities and research centers to the importance of crystal growth, and to work on, in the first stage to establish simple, uncomplicated laboratories for the growth of single crystal. Such laboratories can be supplied with equipment, which are partly available or can be manufactured in the local market. Many references (Articles, Papers, Diagrams, etc..) has been studied, to conclude the most important theoretical principles of Phase transitions,especially of crystallization. The conclusions of this study, are summarized in three Principles; Thermodynamic-, Morphologic-, and Kinetic-Principles. The study is completed by a brief description of the main single crystal growth methods with sketches, of equipment used in each method, which can be considered as primary designs for the equipment, of a new crystal growth laboratory. (author)

Guided Wave Propagation in a Gold Electrode Film on a Pb(Mg1/3Nb2/3)O3−33%PbTiO3 Ferroelectric Single Crystal Substrate

International Nuclear Information System (INIS)

Huang Nai-Xing; LÜ Tian-Quan; Zhang Rui; Wang Yu-Ling; Cao Wen-Wu

2014-01-01

Dispersion relations of Love mode acoustic guided waves propagation in Pb(Mg 1/3 Nb 2/3 )O 3 −33%PbTiO 3 (PMN-0.33 PT) single crystal with a gold electrode film are calculated. There is no cross coupling among Love wave modes, which is conducive to eliminating the cross interference between modes. The general formula is derived to precisely measure the thickness of the electrode. More acoustic energy would be concentrated inside the electrode with the increase of film thickness for a given frequency. Compared with the PZT-5 ceramic, [001] c poled PMN-33%PT single crystal has a slower attenuation of the amplitude of the acoustic guided wave. Therefore, single crystal is extremely suitable for making low loss acoustic wave devices with a high operating frequency

The crystal structure and luminescence quenching of poly- and single-crystalline KYW{sub 2}O{sub 8}:Tb{sup 3+}

Energy Technology Data Exchange (ETDEWEB)

Schwung, Sebastian [Fachbereich Chemieingenieurwesen, Fachhochschule Münster, Stegerwaldstraße 39, 48565 Steinfurt (Germany); Rytz, Daniel, E-mail: rytz@fee-io.de [Forschungsinstitut für mineralische und metallische Werkstoffe-Edelsteine/ Edelmetalle-GmbH (FEE), Struthstraße 2, 55743 Idar-Oberstein (Germany); Heying, Birgit; Rodewald, Ute Ch.; Niehaus, Oliver [Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30 48149 Münster (Germany); Enseling, David [Fachbereich Chemieingenieurwesen, Fachhochschule Münster, Stegerwaldstraße 39, 48565 Steinfurt (Germany); Jüstel, Thomas, E-mail: tj@fh-muenster.de [Fachbereich Chemieingenieurwesen, Fachhochschule Münster, Stegerwaldstraße 39, 48565 Steinfurt (Germany); Pöttgen, Rainer, E-mail: pottgen@uni-muenster.de [Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30 48149 Münster (Germany)

2015-10-15

Terbium-substituted KYW{sub 2}O{sub 8} single crystals of high optical quality were grown by the top seeded solution growth technique. The degree of yttrium–terbium mixed occupancy was determined for two samples through structure refinements on the basis of single crystal X-ray diffractometer data. Temperature dependent magnetic susceptibility data underline the paramagnetic nature of terbium doped crystals. No magnetic ordering is evident down to 2 K. Luminescence measurements yield the typical excitation and emission spectra as expected for Tb{sup 3+} activated materials. The decay time of Tb{sup 3+} decreases linearly with the Tb{sup 3+} concentration, while the excess of thermal quenching does not change significantly. At about 405 K the decay time is reduced by roughly 50% relative to the low-temperature value, both for the powders as for the single crystals. - Highlights: • Single crystalline and powder series of K(Y,Tb)W{sub 2}O{sub 8.} • Refined XRD data of high quality crystals. • Linear decrease of the decay time with Tb{sup 3+} content.

Resistive switching behavior in single crystal SrTiO{sub 3} annealed by laser

Energy Technology Data Exchange (ETDEWEB)

Pan, Xinqiang [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Shuai, Yao, E-mail: yshuai@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Wu, Chuangui, E-mail: cgwu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Luo, Wenbo [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Sun, Xiangyu [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Yuan, Ye; Zhou, Shengqiang [Helmholtz-Zentrum Dresden Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, D-01328 Dresden (Germany); Ou, Xin [State Key Laboratory of Functional Material for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Zhang, Wanli [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2016-12-15

Highlights: • Laser annealing was used to introduce oxygen vacancies into the single crystal SrTiO{sub 3}. • The effect of laser annealing with different fluence on the single crystal SrTiO{sub 3} was systematically studied. • The concentration of oxygen vacancies can be tuned by changing the fluence of laser. • Resistive switching behavior was observed in the sample with relatively high laser fluence after an electro-forming process. - Abstract: Single crystal SrTiO{sub 3} (STO) wafers were annealed by XeCl laser (λ = 308 nm) with different fluences of 0.4 J/cm{sup 2}, 0.6 J/cm{sup 2} and 0.8 J/cm{sup 2}, respectively. Ti/Pt electrodes were sputtered on the surface of STO wafer to form co-planar capacitor-like structures of Pt/Ti/STO/Ti/Pt. Current-Voltage measurements show that the leakage current is enhanced by increasing laser fluence. Resistive switching behavior is only observed in the sample annealed by laser with relatively high fluence after an electro-forming process. The X-ray photoelectron spectroscopy measurements indicate that the amount of oxygen vacancies increases with the increase of laser fluence. This work indicates resistive switching appears when enough oxygen vacancies are generated by the laser, which form conductive filaments under an external electric field.

Scintillation properties of Er-doped Y3Al5O12 single crystals

International Nuclear Information System (INIS)

Yamaji, Akihiro; Ogino, Hiraku; Fujimoto, Yutaka; Suzuki, Akira; Yanagida, Takayuki; Yokota, Yuui; Kurosawa, Shunsuke; Yoshikawa, Akira

2013-01-01

Er-doped Y 3 Al 5 O 12 single crystals with different Er concentrations of 0.1, 1.0, 10, 30, and 50% were grown by the micro-pulling down method. There were several absorption lines due to the Er 3+ 4f-4f transitions in the transmittance spectra and these lines correspond to the transitions from the ground state of 4 I 15/2 to the excited states. The photo- and radio-luminescence spectra showed Er 3+ 4f-4f emissions. Relative light yield under 5.5 MeV alpha-ray irradiation of Er 0.1%:Y 3 Al 5 O 12 was estimated to be 63% of that of Bi 4 Ge 3 O 12 . -- Highlights: •Er doped Y 3 Al 5 O 12 single crystal scintillators were grown with different Er concentrations. •Optical properties associated with 4f-4f transition were evaluated. •Radio luminescence spectra measurements were performed under 5.5 MeV alpha-ray irradiation. •The highest light yield was estimated to be 63% of that of Bi 4 Ge 3 O 12 under 5.5 MeV alpha-ray irradiation

Growth and magnetooptical properties of anisotropic TbF3 single crystals

Science.gov (United States)

Valiev, Uygun V.; Karimov, Denis N.; Burdick, Gary W.; Rakhimov, Rakhim; Pelenovich, Vasiliy O.; Fu, Dejun

2017-06-01

This paper investigates the Faraday effect and absorption and luminescence spectra of single-crystal TbF3 measured at 90 K and 300 K. The optical-quality single-phase TbF3 crystals (structural type β-YF3) were grown by the Bridgman technique. Faraday rotation angles were measured at remagnetization along the [100] crystallographic axis. Low temperature optical measurements were carried out along the [100] axis. "Quasi-doublet" sublevels with energy at 0 cm-1, 65 cm-1, and 190 cm-1, and also a singlet sublevel with energy at 114 cm-1 located in the ground 7F6 multiplet were determined from the low temperature luminescence spectra. The Van-Vleck behavior of the magnetic susceptibility χb can be satisfactorily explained by the magnetic mixing of wave functions belonging to the ground and first excited "quasi-doublet" sublevels at 0 and 65 cm-1, respectively. Analysis of the oscillation dependences of the rotation angle showed that the value of the natural birefringence (Δn ≈ 0.0186) remains nearly constant within the wavelength and temperature ranges under investigation. As the temperature decreases, we find significant increases in the oscillation amplitude of the rotation angle and in the Verdet constant V. The spectral dependences V(χ) are linear throughout the temperature range. The magnetooptical activity of TbF3 can be explained by means of the spin- and parity-allowed electric-dipole 4f → 5d transitions in the Tb3+ ions.

Growth of Ca, Zr co-doped BaTiO3 lead-free ferroelectric single crystal and its room-temperature piezoelectricity

Directory of Open Access Journals (Sweden)

Donglin Liu

2017-09-01

Full Text Available Lead-free Ca, Zr co-doped BaTiO3 (BCZT single crystal with a dimension up to 2mm×2mm×2mm was grown by a spontaneous nucleation technique using KF as the flux. The composition of the studied single crystal was defined to be Ba0.798Ca0.202Zr0.006Ti0.994O3, corresponding to a tetragonal phase at room temperature. The oriented single crystal exhibited a quasi-static piezoelectric constant of approximately 232 pC/N. The effective piezoelectric coefficient d33* of the single domain crystal obtained under a unipolar electric field of 35 kV/cm was 179 pm/V. Rayleigh analysis was used to identify the intrinsic and extrinsic contributions to the room-temperature piezoelectricity of BCZT single crystal. The extrinsic contribution was estimated up to 40% due to the irreversible domain wall movement. Furthermore a sixth-order polynomial of Landau expansion was employed to analyze the intrinsic contribution to piezoelectricity of BCZT single crystal. The large energy barriers inhibited polarization rotations, leading to the relatively low piezoelectricity.

DETERMINATION OF VICKERS MICROHARDNESS IN β-Ga2O3 SINGLE CRYSTALS GROWN FROM THEIR OWN MELT

Directory of Open Access Journals (Sweden)

L. I. Guzilova

2015-05-01

Full Text Available The results of microhardness measurements of β-Ga2O3 single crystals for (001 crystallographic face are reported. The crystals were grown by the free crystallization with the "Garnet-2M" equipment. Microhardness values ​​ were determined by the Vickers method at varying loads. A four-sided diamond pyramid was used as an indenter. The average value of gallium oxide microhardness was equal to 8.91 GPa. We have carried out comparison of the values ​​obtained with the microhardness for the other wide bandgap semiconductors - epitaxial GaN layers grown on 6H-SiC and GaP layers grown on GaP:S. The findings are usable for machining process development of β-Ga2O3 single crystal substrates. In particular, silicon carbide and electrocorundum may be recommended for β-Ga2O3 machine processing.

Scattering Study of Conductive-Dielectric Nano/Micro-Grained Single Crystals Based on Poly(ethylene glycol, Poly(3-hexyl thiophene and Polyaniline

Directory of Open Access Journals (Sweden)

Samira Agbolaghi

2017-12-01

Full Text Available Two types of rod-coil block copolymers including poly(3-hexylthiophene-block-poly(ethylene glycol (P3HT-b-PEG and PEG-block-polyaniline (PANI were synthesized using Grignard metathesis polymerization, Suzuki coupling, and interfacial polymerization. Afterward, two types of single crystals were grown by self-seeding methodology to investigate the coily and rod blocks in grafted brushes and ordered crystalline configurations. The conductive P3HT fibrillar single crystals covered by the dielectric coily PEG oligomers were grown from toluene, xylene, and anisole, and characterized by atomic force microscopy (AFM and grazing wide angle X-ray scattering (GIWAXS. Longer P3HT backbones resulted in folding, whereas shorter ones had a high tendency towards backbone lamination. The effective factors on folding of long P3HT backbones in the single crystal structures were the solvent quality and crystallization temperature. Better solvents due to decelerating the growth condition led to a higher number of foldings. Via increasing the crystallization temperature, the system decreased the folding number to maintain its stability. Poorer solvents also reflected a higher stacking in hexyl side chain and π-π stacking directions. The dielectric lamellar PEG single crystals sandwiched between the PANI nanorods were grown from amyl acetate, and analyzed using the interface distribution function (IDF of SAXS and AFM. The molecular weights of PANI and PEG blocks and crystallization temperature were focused while studying the grown single crystals.

Crystal growth and scintillation properties of Er-doped Lu3Al5O12 single crystals

International Nuclear Information System (INIS)

Sugiyama, Makoto; Fujimoto, Yutaka; Yanagida, Takayuki; Totsuka, Daisuke; Kurosawa, Shunsuke; Futami, Yoshisuke; Yokota, Yuui; Chani, Valery; Yoshikawa, Akira

2012-01-01

Er-doped Lu 3 Al 5 O 12 (Er:LuAG) single crystalline scintillators with different Er concentrations of 0.1, 0.5, 1, and 3% were grown by the micro-pulling-down (μ-PD) method. The grown crystals were composed of single-phase material, as demonstrated by powder X-ray diffraction (XRD). The radioluminescence spectra measured under 241 Am α-ray excitation indicated host emission at approximately 350 nm and Er 3+ 4f-4f emissions. According to the pulse height spectra recorded under γ-ray irradiation, the 0.5% Er:LuAG exhibited the highest peak channel among the samples. The γ-ray excited decay time profiles were well fitted by the two-component exponential approximation (0.8 μs and 6-10 μs).

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.

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.

Optical characteristics of BaGa{sub 2}S{sub 4}:Ho{sup 3+} and BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals

Energy Technology Data Exchange (ETDEWEB)

Choe, Sung-Hyu [Chosun University, Kwangju (Korea, Republic of); Jin, Moon-Seog [Dongshin University, Naju (Korea, Republic of); Kim, Wha-Tek [Chonnam National University, Kwangju (Korea, Republic of)

2005-11-15

BaGa{sub 2}S{sub 4}, BaGa{sub 2}S{sub 4}:Ho{sup 3+}, BaGa{sub 2}Se{sub 4}, and BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the single crystals were investigated in the temperature region from 11 K to 300 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Two broad emission bands were observed in the photoluminescence spectra of the single crystals. These bands were attributed to donor-acceptor pair recombinations. Sharp emission peaks were observed in the BaGa{sub 2}S{sub 4}:Ho{sup 3+} and the BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals and were assigned to radiation recombination between split Stark levels of Ho{sup 3+}.

Peak effect in untwinned YBa 2Cu 3O 7-δ single crystals

Science.gov (United States)

D'Anna, G.; André, M.-O.; Indenbom, M. V.; Benoit, W.

1994-12-01

We report on the observation of a weak effect of the critical current density in untwinned YBa 2Cu 3O 7-δ single crystals of different purity, using a low frequency torsion pendulum. We construct the peak effect line and the irreversibility line.

Reversible air-induced optical and electrical modulation of methylammonium lead bromide (MAPbBr3) single crystals

Science.gov (United States)

Zhang, Huotian; Liu, Yiting; Lu, Haizhou; Deng, Wan; Yang, Kang; Deng, Zunyi; Zhang, Xingmin; Yuan, Sijian; Wang, Jiao; Niu, Jiaxin; Zhang, Xiaolei; Jin, Qingyuan; Feng, Hongjian; Zhan, Yiqiang; Zheng, Lirong

2017-09-01

The photoluminescence (PL) variations of organic-inorganic hybrid lead halide perovskites in different atmospheres are well documented, while the fundamental mechanism still lacks comprehensive understandings. This study reports the reversible optical and electrical properties of methylammonium lead bromide (MAPbBr3 or CH3NH3PbBr3) single crystals caused by air infiltration. With the change in the surrounding atmosphere from air to vacuum, the PL intensity of perovskite single crystals decreases, while the conductivity increases. By means of first-principles computational studies, the shallow trap states are considered as key elements in PL and conductivity changes. These results have important implications for the characterization and application of organic-inorganic hybrid lead halide perovskites in vacuum.

Defect characterization of Ga4Se3S layered single crystals by ...

Indian Academy of Sciences (India)

Trapping centres in undoped Ga 4 Se 3 S single crystals grown by Bridgman method were characterized for the first time by thermoluminescence (TL) measurements carried out in the low temperature range of 15−300 K. After illuminating the sample with blue light (∼470 nm) at 15 K, TL glow curve exhibited one peak ...

Inkjet printing of single-crystal films.

Science.gov (United States)

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

2011-07-13

The use of single crystals has been fundamental to the development of semiconductor microelectronics and solid-state science. Whether based on inorganic or organic materials, the devices that show the highest performance rely on single-crystal interfaces, with their nearly perfect translational symmetry and exceptionally high chemical purity. Attention has recently been focused on developing simple ways of producing electronic devices by means of printing technologies. 'Printed electronics' is being explored for the manufacture of large-area and flexible electronic devices by the patterned application of functional inks containing soluble or dispersed semiconducting materials. However, because of the strong self-organizing tendency of the deposited materials, the production of semiconducting thin films of high crystallinity (indispensable for realizing high carrier mobility) may be incompatible with conventional printing processes. Here we develop a method that combines the technique of antisolvent crystallization with inkjet printing to produce organic semiconducting thin films of high crystallinity. Specifically, we show that mixing fine droplets of an antisolvent and a solution of an active semiconducting component within a confined area on an amorphous substrate can trigger the controlled formation of exceptionally uniform single-crystal or polycrystalline thin films that grow at the liquid-air interfaces. Using this approach, we have printed single crystals of the organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C(8)-BTBT) (ref. 15), yielding thin-film transistors with average carrier mobilities as high as 16.4 cm(2) V(-1) s(-1). This printing technique constitutes a major step towards the use of high-performance single-crystal semiconductor devices for large-area and flexible electronics applications.

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

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

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.

Growth of (CH 3) 2NH 2CuCl 3 single crystals using evaporation method with different temperatures and solvents

Science.gov (United States)

Chen, L. M.; Tao, W.; Zhao, Z. Y.; Li, Q. J.; Ke, W. P.; Wang, X. M.; Liu, X. G.; Fan, C.; Sun, X. F.

2010-10-01

The bulk single crystals of low-dimensional magnet (CH 3) 2NH 2CuCl 3 (DMACuCl 3 or MCCL) are grown by a slow evaporation method with different kinds of solvents, different degrees of super-saturation of solution and different temperatures of solution, respectively. Among three kinds of solvent, methanol, alcohol and water, alcohol is found to be the best one for growing MCCL crystals because of its structural similarity to the raw materials and suitable evaporation rate. The best growth temperature is in the vicinity of 35 °C. The problem of the crystals deliquescing in air has been solved through recrystallization process. The crystals are characterized by means of X-ray diffraction, specific heat and magnetic susceptibility.

Structure and magnetic properties of flux grown single crystals of Co3-xFexSn2S2 shandites

Science.gov (United States)

Kassem, Mohamed A.; Tabata, Yoshikazu; Waki, Takeshi; Nakamura, Hiroyuki

2016-01-01

We report a successful single crystal growth of the shandite-type half-metallic ferromagnet Co3Sn2S2, and its Fe-substituted compounds, Co3-xFexSn2S2, by employing the flux method. Although Fe3Sn2S2 is unstable phase, we found that using the self Sn flux enables us to obtain single phase crystals up to x=0.53. The chemical composition of the grown plate-shaped single crystals was examined using wavelength-dispersive X-ray spectroscopy. The shandite structure with R 3 ̅m symmetry was confirmed by powder X-ray diffraction and the crystal structure parameters were refined using the Rietveld method. Magnetization measurements show suppression of the ferromagnetic order upon Fe-substitution , as well as in other substituted systems such as In- and Ni-substituted Co3Sn2S2. The almost identical magnetic phase diagrams of the Fe- and In-substituted compounds indicate that the electron number is dominantly significant to the magnetism in the Co-based shandite.

Magnetic phase transitions in Er7Rh3 studied on single crystals

International Nuclear Information System (INIS)

Tsutaoka, Takanori; Obata, Keisuke; Cheyvuth, Seng; Koyama, Keiichi

2014-01-01

Highlights: • Magnetic and electrical properties of Er 7 Rh 3 were studied on single crystals. • The magnetic phase diagram along the c-axis was constructed. • The field-induced magnetic transitions in Er 7 Rh 3 can be explained by the magnetic structure with two magnetic propagation vectors. • The anomalies of electrical resistivity can also be described by the magnetic structure in Er 7 Rh 3 . - Abstract: Magnetic phase transitions in Er 7 Rh 3 with the Th 7 Fe 3 type hexagonal structure have been studied on single crystals by measuring magnetization, magnetic susceptibility and electrical resistivity. Er 7 Rh 3 possesses antiferromagnetic state below T N = 13 K. In the ordered state, the two successive magnetic transitions at T t1 = 6.2 K and T t2 = 4.5 K were observed. Several field-induced magnetic transitions were also observed along the a- and c-axes below T N ; magnetic field H – temperature T phase diagram along the c-axis was constructed. The field-induced magnetic transitions in Er 7 Rh 3 can be explained by the magnetic structure with two magnetic propagation vectors which were derived by the previous neutron diffraction studies. Electrical resistivity shows humps just below the magnetic transition temperatures, T N and T t1 due to the super-zone gap formation at the Fermi level; these anomalies can also be described by the magnetic structure changes in Er 7 Rh 3

Crystal growth and characterization of new semiorganic nonlinear optical single crystals

Energy Technology Data Exchange (ETDEWEB)

Kulshrestha, Shobha, E-mail: shobha011986@gmail.com; Shrivastava, A. K., E-mail: ashwaniaks@rediffmail.com [School of Studies in Physics, Jiwaji University Gwalior (M.P.) – 474 011 (India)

2016-05-06

An organic material of a L-histidine monohydrochloride single crystal was grown in a distilled water solution using the slow evaporation method at 40–45°C. The grown crystal was transparent and colourless, with a size of about 20 × 9 × 5 mm{sup 3}, obtained within a period of 21 days. The solubility of grown crystals have found out at various temperatures. The UV-visible transmittance studies show that the grown crystals have wide optical transparency in the entire visible region It is observed that the crystal has transparency window from 255nm to 700nm and its energy gap (Eg) found to be is 3.1eV. The grown crystal was subjected to powder X-ray diffraction analysis, confirming that the orthorhombic crystalline nature of the crystal. To identify the surface morphology, the as grown crystal was subjected to FE-SEM technique. The chemical composition of the grown crystal was estimated by Energy dispersive X-ray analysis. The optical behaviour of the grown crystal was analyzed by PL study.

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

International Nuclear Information System (INIS)

Molnar, P.; Sittner, P.; Novak, V.; Lukas, P.

2008-01-01

A neutron single crystal diffraction method for inspecting the quality of martensite single crystals is introduced. True interface-free martensite single crystals are indispensable for, e.g. measurement of elastic constants of phases by ultrasonic techniques. The neutron diffraction method was used to detect and distinguish the presence of individual lattice correspondence variants of the 2H orthorhombic martensite phase in Cu-Al-Ni as well as to follow the activity of twinning processes during the deformation test on the martensite variant single crystals. When preparing the martensite single variant prism-shaped crystals by compression deformation method, typically a small fraction of second unwanted martensitic variant (compound twin) remains in the prism samples. Due to the very low stress (∼1 MPa) for the compound twinning in many shape memory alloys, it is quite difficult not only to deplete the martensite prisms of all internal interfaces but mainly to keep them in the martensite single variant state for a long time needed for further investigations

Synthesis of a mesoporous single crystal Ga2O3 nanoplate with improved photoluminescence and high sensitivity in detecting CO.

Science.gov (United States)

Yan, Shicheng; Wan, Lijuan; Li, Zhaosheng; Zhou, Yong; Zou, Zhigang

2010-09-14

A new approach is proposed to synthesize a mesoporous single crystal Ga(2)O(3) nanoplate by heating a single crystal nanoplate of GaOOH, which involves an ion exchange between KGaO(2) and CH(3)COOH at room temperature for the formation of GaOOH and pseudomorphic and topotactic phase transformation from GaOOH to Ga(2)O(3).

Czochralski growth and optical properties of Li 6Gd 1-xEu x(BO 3) 3 ( x=0-1) single crystals

Science.gov (United States)

Yavetskiy, R. P.; Dolzhenkova, E. F.; Dubovik, M. F.; Korshikova, T. I.; Tolmachev, A. V.

2005-04-01

It was shown that a continuous series of Li 6Gd 1-xEu x(BO 3) 3 solid solutions exist within the whole concentration range ( x=0-1). Li 6Gd 1-xEu x(BO 3) 3 ( x=0-0.03; 1) single crystals up to 25 mm in length and up to 20 mm in diameter have been grown by the Czochralski method. The structural perfection of the crystals has been estimated from etch patterns and XPA analysis results. The optical absorption and thermally stimulated luminescence of the grown crystals has been studied.

Doping with lead of single crystals of solid solutions of Sbsub(1,5)Bisub(0,5)Tlsub(3)-Bisub(2)Sesub(3)

International Nuclear Information System (INIS)

Abrikosov, N.Kh.; Ivanova, L.D.; Polikarpova, N.V.; Galechyan, M.G.

1984-01-01

By the Czochralski method with liquid phase additional feeding single crystals of solid solutions of the Sbsub(1.5)Bisub(0.5)Tesub(3)-Bisub(2)Sesub(3) system with 0, 10 and 15 mol.% of Bi 2 Se 3 content doped with lead up to 1.37 at/cm 3 are grown. Lead content in crystals and alloys is determined by the atom-abmethod using the scale of standard solutions. It has been found that the effective coefficient of lead distribution in investigated solutions is approximately 0.5. It is shown that lead addition leads to increase of electric conductivity and heat conductivity and decrease of thermoelectric coeffcient at the expense of current carriers concentration growth, the lead in crystals of solid solutions of the Sbsub(1.5)Bisub(0.5)Tesub(3)-Bisub(2)Sesub(3) system being a single charge acceptor

Highly polarized single-c-domain single-crystal Pb(Mn,Nb)O(3)-PZT thin films.

Science.gov (United States)

Wasa, Kiyotaka; Adachi, Hideaki; Nishida, Ken; Yamamoto, Takashi; Matsushima, Tomoaki; Kanno, Isaku; Kotera, Hidetoshi

2012-01-01

In-plane unstrained single-c-domain/single-crystal thin films of PZT-based ternary ferroelectric perovskite, ξPb(Mn,Nb)O3-(1 - ξ)PZT, were grown on SrRuO(3)/Pt/MgO substrates using magnetron sputtering followed by quenching. The sputtered unstrained thin films exhibit unique ferroelectric properties: high coercive field, Ec > 180 kV/cm, large remanent polarization, P(r) = 100 μC/cm(2), small relative dielectric constants, ε* = 100 to 150, high Curie temperature, Tc = ~600 °C, and bulk-like large transverse piezoelectric constants, e31,f = -12.0 C/m(2) for PZT(48/52) at ξ = 0.06. The unstrained thin films are an ideal structure to extract the bulk ferroelectric properties. Their micro-structures and ferroelectric properties are discussed in relation to the potential applications for piezoelectric MEMS. © 2012 IEEE

Magnetic properties of the tetragonal RCuGa{sub 3} (R=Pr, Nd and Gd) single crystals

Energy Technology Data Exchange (ETDEWEB)

Nagalakshmi, R., E-mail: nagaphys@yahoo.com [Department of Physics, National Institute of Technology, Tiruchirappalli 6200015 (India); Kulkarni, Ruta; Dhar, S.K.; Thamizhavel, A. [DCMPMS, Tata Institute of Fundamental Research, Mumbai 400005 (India); Krishnakumar, V. [Department of Physics, Periyar University, Salem 636011 (India); Reiffers, Marian; Čurlík, Ivan [Institute of Experimental Physics, Watsonova 47, SK-040 01 Kosice (Slovakia); Department of Physics, University of Presov, 17 Novembra 1, SK-080 01 (Slovakia); Hagemann, Hans; Lovy, Dominique [Department of Physical Chemistry, University of Geneva, Geneva (Switzerland); Nallamuthu, S. [Department of Physics, National Institute of Technology, Tiruchirappalli 6200015 (India)

2015-07-15

Single crystals of tetragonal RCuGa{sub 3} (R=La, Pr, Nd and Gd), with BaNiSn{sub 3} type structure (space group I4 mm), have been grown by high temperature solution growth technique using Ga as flux. Their magnetic properties were determined by heat capacity and the measurement of magnetization and electrical resistivity along [100] and [001] directions. Except LaCuGa{sub 3}, the compounds order magnetically. PrCuGa{sub 3} undergoes a ferromagnetic transition with Curie temperature of 4.6 K. NdCuGa{sub 3} shows a bulk magnetic transition at 3.3 K. The data on GdCuGa{sub 3} indicate combined characteristics of spin glass and antiferromagnetic behavior at low temperatures. From the Schottky heat capacity data the crystal electric field level energy spectra have been determined. Further we have performed temperature dependent measurements of electron spin resonance (ESR) on GdCuGa{sub 3} between 11 K and room temperature. The ESR data indicate an enhancement of magnetic fluctuations associated with spin reorientation and both homogeneous and inhomogeneous thermal broadening of the linewidth. - Highlights: • RCuGa{sub 3} (R=La, Pr, Nd and Gd) single crystals were grown by flux technique. • The compounds exhibit long range magnetic ordering. • Crystal electric field levels have been derived from Schottky heat capacity. • Electron spin resonance (ESR) studies of GdCuGa{sub 3} are also discussed.

Crystal growth, optical properties, and laser operation of Yb3+-doped NYW single crystal

Science.gov (United States)

Cheng, Y.; Xu, X. D.; Yang, X. B.; Xin, Z.; Cao, D. H.; Xu, J.

2009-11-01

Laser crystal Yb3+-doped NaY(WO4)2 (Yb:NYW) with excellent quality has been grown by Czochralski technique. The rocking curves from (400) plane of as-grown Yb:NYW crystal was measured and the full-width value at half-maximum was 19.92″. The effective segregation coefficients were measured by the X-ray fluorescence method. The polarized absorption spectra and the fluorescence spectra of Yb:NYW crystal were measured at room temperature. The fluorescence decay lifetime of Yb3+ ion in NYW crystal has been investigated. The spectroscopic parameters of Yb:NYW crystal are calculated and compared with those of Yb:YAG crystal. A continuous wave output power of 3.06 W at 1031 nm was obtained with a slope efficiency of 42% by use of diode pumping.

Growth of (CH$_3$)$_2$NH$_2$CuCl$_3$ single crystals using evaporation method with different temperatures and solvents

OpenAIRE

Chen, L. M.; Tao, W.; Zhao, Z. Y.; Li, Q. J.; Ke, W. P.; Wang, X. M.; Liu, X. G.; Fan, C.; Sun, X. F.

2013-01-01

The bulk single crystals of of low-dimensional magnet (CH$_3$)$_2$NH$_2$CuCl$_3$ (DMACuCl$_3$ or MCCL) are grown by a slow evaporation method with different kinds of solvents, different degrees of super-saturation of solution and different temperatures of solution, respectively. Among three kinds of solvent, methanol, alcohol and water, alcohol is found to be the best one for growing MCCL crystals because of its structural similarity to the raw materials and suitable evaporation rate. The bes...

Resistance to {gamma} irradiation of LaBr{sub 3}:Ce and LaCl{sub 3}:Ce single crystals

Energy Technology Data Exchange (ETDEWEB)

Normand, S. [CEA-Recherche Technologique, DETECS/SSTM CE Saclay F-91191 Gif Sur Yvette Cedex (France)]. E-mail: stephane.normand@cea.fr; Iltis, A. [Saint-Gobain Crystals, 104 Route de Larchant, 77140 St Pierre les Nemours (France); Bernard, F. [Saint-Gobain Crystals, 104 Route de Larchant, 77140 St Pierre les Nemours (France); Domenech, T. [CEA-Recherche Technologique, DETECS/SSTM CE Saclay F-91191 Gif Sur Yvette Cedex (France); Delacour, P. [CEA-Recherche Technologique, DETECS/SSTM CE Saclay F-91191 Gif Sur Yvette Cedex (France)

2007-03-11

LaBr{sub 3}:Ce (Brillance 380) and LaCl{sub 3}:Ce (Brillance 350) both exhibit a very good energy resolution and energy linearity response. They are also more sensitive to {gamma}-rays than NaI(Tl) detectors, due to their higher density. The aim of this work is to determine the behaviour of those new single crystals in comparison with NaI(Tl) under severe {gamma}-ray irradiation. Therefore we have irradiated three 25 by 25 mm cylinder crystals encapsulated in air-tight aluminium housing with {sup 60}Co beam. Crystals were tested as stand-alone material not to test the impact of radiation to our photomultiplier tube (PMT). Only encapsulated crystals (alone, without PMTs) were irradiated during several periods to achieve the final 3.4 kGy integrated dose. Intermediate measurements of {sup 137}Cs spectrum were done in order to evaluate the impact of the dose on the studied crystal performances. The radiation hardness of LaBr{sub 3}:Ce and LaCl{sub 3}:Ce was then compared to NaI(Tl). We show in this paper that up to 3.4 kGy no permanent modification of the energy resolution nor colour change is observed for LaBr{sub 3}:Ce and LaCl{sub 3}:Ce crystals. The light output also seems quite stable. This is in stark contrast with the behaviour of NaI:Tl which exhibits continuously decreasing light output, colour change and worsening of energy resolution for doses above 5 Gy.

Low Leakage Superconducting Tunnel Junctions with a Single Crystal Al2O3 Barrier

Science.gov (United States)

2016-03-30

10-6 Torr ). In this low-pressure oxygen environment, Auger electron spectroscopy (AES) study shows that while oxidation of the base layer is...three layers were grown in situ in an ultra high vacuum (UHV) system with a nominal base pressure of ~1×10-10 Torr . First, a 120~150 nm thick...high-temperature annealing in order to crystallize the amorphous AlOx into a single-crystal Al2O3. After the sample was cooled to room temperature

Single crystal study of antiferromagnetic CePd3Al9

International Nuclear Information System (INIS)

Baumbach, R E; Scott, B L; Ronning, F; Thompson, J D; Bauer, E D

2014-01-01

Single crystal x-ray diffraction, magnetic susceptibility (M), heat capacity (C), and electrical resistivity (ρ) measurements are reported for specimens of the new tetragonal compound CePd 3 Al 9 , which forms in a new structure type. X-ray diffraction measurements reveal that the nearest neighbor Ce–Ce distances are large (d Ce–Ce  = 5.272 Å), suggesting that this compound may be described as a stoichiometric dilute Kondo lattice. Thermodynamic and transport measurements reveal antiferromagnetic order near T N  = 0.9 K. The ordered ground state emerges from a lattice of localized Ce ions that are weakly hybridized with the conduction electrons, as revealed by the moderate electronic coefficient of the specific heat γ ≈ 45 mJ mol −1  K −2 (extrapolated from above T N ) and the lack of evidence for Kondo coherence in the magnetic susceptibility and electrical resistivity. The application of a magnetic field initially suppresses the magnetic order at a rate of −0.04 K kOe −1 , but Zeeman splitting of the doublet ground state produces a nonmagnetic singlet before T N reaches zero. The data additionally reveal that chemical/structural disorder plays an important role, as evidenced by results from single crystal x-ray diffraction, the broadness of the peak at T N in the heat capacity, and the small residual resistivity ratio RRR = ρ 300 K /ρ 0  = 1.3. (paper)

Preparation of metastable bcc permalloy epitaxial thin films on GaAs(011){sub B3} single-crystal substrates

Energy Technology Data Exchange (ETDEWEB)

Ohtake, Mitsuru, E-mail: ohtake@futamoto.elect.chuo-u.ac.jp [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Higuchi, Jumpei; Yabuhara, Osamu [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan); Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan)

2011-09-30

Permalloy (Py) single-crystal films with bcc structure were obtained on GaAs(011){sub B3} single-crystal substrates by ultra high vacuum rf magnetron sputtering. The film growth and the detailed film structures were investigated by refection high energy electron diffraction and pole figure X-ray diffraction. bcc-Py films epitaxially grow on the substrates in the orientation relationship of Py(011)[011-bar]{sub bcc} || GaAs(011)[011-bar]{sub B3}. The lattice constant of bcc-Py film is determined to be a = 0.291 nm. With increasing the film thickness, parts of the bcc crystal transform into more stable fcc structure by atomic displacement parallel to the bcc{l_brace}011{r_brace} close-packed planes. The resulting film thus consists of a mixture of bcc and fcc crystals. The phase transformation mechanism is discussed based on the experimental results. The in-plane magnetization properties reflecting the magnetocrystalline anisotropy of bcc-Py crystal are observed for the Py films grown on GaAs(011){sub B3} substrates.

Electron paramagnetic resonance of gamma irradiated (CH3)3NHClO4 and CH3NH3ClO4 single crystals

International Nuclear Information System (INIS)

Yavuz, Metin; Koeksal, Fevzi

1999-01-01

Gamma irradiation damage centers in (CH 3 ) 3 NHClO 4 and CH 3 NH 3 ClO 4 single crystals have been investigated at room temperature by the electron paramagnetic resonance (EPR) technique. It has been found that γ-irradiation produces the (CH 3 ) 3 N + radical in the first, and NH + 3 and ClO 3 radicals in the second compound. The EPR parameters of the observed radicals have been determined and discussed

Development of n- and p-type Doped Perovskite Single Crystals Using Solid-State Single Crystal Growth (SSCG) Technique

Science.gov (United States)

2017-10-09

for AGG should be minimal. For this purpose, the seeds for AGG may also be provided externally. This process is called the solid-state single...bonding process . Figure 31 shows (a) the growth of one large single crystal from one small single crystal seed as well as (b) the growth of one...one bi-crystal seed : One large bi-crystal can be grown from one small bi-crystal by SSCG process . Fig. 32. Diffusion bonding process for

Rise and fall of ferromagnetism in O-irradiated Al2O3 single crystals

International Nuclear Information System (INIS)

Li, Qiang; Xu, Juping; Liu, Jiandang; Du, Huaijiang; Ye, Bangjiao

2015-01-01

In dilute magnetic semiconductors studies, sapphire was usually used as non-magnetic substrate for films. We observed weak ferromagnetic component in Al 2 O 3 single crystal substrate, and excluded the possibility of ferromagnetic contaminations carefully by inductively coupled plasma mass spectrometry and X-ray photoelectron spectroscopy. The ferromagnetism rise and fall during the process of annealing-oxygen irradiation-annealing of the sapphire. The ferromagnetic changes are consistent with Al-vacancy related defects detected by positron annihilation spectroscopy. With first-principle calculations, we confirm that Al-vacancy can introduce magnetic moment for 3 μB in Al 2 O 3 crystal and form stable V Al -V Al ferromagnetic coupling at room temperature

Photoresponse of CsPbBr3 and Cs4PbBr6 Perovskite Single Crystals.

Science.gov (United States)

Cha, Ji-Hyun; Han, Jae Hoon; Yin, Wenping; Park, Cheolwoo; Park, Yongmin; Ahn, Tae Kyu; Cho, Jeong Ho; Jung, Duk-Young

2017-02-02

High-quality and millimeter-sized perovskite single crystals of CsPbBr 3 and Cs 4 PbBr 6 were prepared in organic solvents and studied for correlation between photocurrent generation and photoluminescence (PL) emission. The CsPbBr 3 crystals, which have a 3D perovskite structure, showed a highly sensitive photoresponse and poor PL signal. In contrast, Cs 4 PbBr 6 crystals, which have a 0D perovskite structure, exhibited more than 1 order of magnitude higher PL intensity than CsPbBr 3 , which generated an ultralow photoresponse under illumination. Their contrasting optoelectrical characteristics were attributed to different exciton binding energies, induced by coordination geometry of the [PbBr 6 ] 4- octahedron sublattices. This work correlated the local structures of lead in the primitive perovskite and its derivatives to PL spectra as well as photoconductivity.

Polarized Raman scattering in single crystals of Nd0.7Sr0.3MnO3

Indian Academy of Sciences (India)

2. Experimental. The single crystal was grown in an infrared image furnace by the floating zone technique. Raman measurements were performed in the spectral .... [3] C Xiong, Q Li, H L Ju, S N Mao, L Senapati, X X Xi, R L Green and T Venkatesan, Appl. Phys. Lett. 66, 1427 (1995). [4] N H Nam, R Mathieu, P Nordblad, N V ...

Highly Efficient LiYF4:Yb(3+), Er(3+) Upconversion Single Crystal under Solar Cell Spectrum Excitation and Photovoltaic Application.

Science.gov (United States)

Chen, Xu; Xu, Wen; Song, Hongwei; Chen, Cong; Xia, Haiping; Zhu, Yongsheng; Zhou, Donglei; Cui, Shaobo; Dai, Qilin; Zhang, Jiazhong

2016-04-13

Luminescent upconversion is a promising way to harvest near-infrared (NIR) sunlight and transforms it into visible light that can be directly absorbed by active materials of solar cells and improve their power conversion efficiency (PCE). However, it is still a great challenge to effectively improve the PCE of solar cells with the assistance of upconversion. In this work, we demonstrate the application of the transparent LiYF4:Yb(3+), Er(3+) single crystal as an independent luminescent upconverter to improve the PCE of perovskite solar cells. The LiYF4:Yb(3+), Er(3+) single crystal is prepared by an improved Bridgman method, and its internal quantum efficiency approached to 5.72% under 6.2 W cm(-2) 980 nm excitation. The power-dependent upconversion luminescence indicated that under the excitation of simulated sunlight the (4)F(9/2)-(4)I(15/2) red emission originally results from the cooperation of a 1540 nm photon and a 980 nm photon. Furthermore, when the single crystal is placed in front of the perovskite solar cells, the PCE is enhanced by 7.9% under the irradiation of simulated sunlight by 7-8 solar constants. This work implies the upconverter not only can serve as proof of principle for improving PCE of solar cells but also is helpful to practical application.

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.

Morphology and kinetics of polymorphic transformations in K{sub 0.965}Rb{sub 0.035}NO{sub 3} single crystals

Energy Technology Data Exchange (ETDEWEB)

Nasirov, V. I.; Bairamov, R. B., E-mail: bayramov.razim@mail.ru; Nasirov, E. V. [Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan)

2015-12-15

Polymorphic transformations in K{sub 0.965}Rb{sub 0.035}NO{sub 3} single crystals have been investigated by optical microscopy and X-ray diffraction. The equilibrium temperature between modifications II and III of the crystal studied is determined to be T = 452 ± 0.5 K. It is found that polymorphic transformations are of the single crystal ↔ single crystal type and occur with the formation and growth of nuclei of new crystals in matrix ones at II ↔ III transformations. An empirical dependence of the growth rate of modification III on temperature is established in the form ϑ = ϑ = (–0.478ΔT + 0.712ΔT{sup 2}–0.00041ΔT{sup 3}) × 10{sup –2} cm/s (ΔT = T{sub tr}–T{sub 0}, where T{sub tr} is the transformation temperature and T{sub 0} is the equilibrium temperature)

Structural characterization of Li1.2v3o8 insertion electrodes by single-crystal x-ray-diffraction

CSIR Research Space (South Africa)

De Picciotto, LA

1993-08-01

Full Text Available The crystal structures of Li1.2V3O8 and a lithiated product Li4.0V3O8 have been determined by single-crystal X-ray diffraction methods. The structure refinement of Li1.2V308 confirms that of Li1+xV3O8(x almost-equal-to 0) reported by Wadsley thirty...

Magnetic, transport, and optical properties of Ca{sub 0.85}Eu{sub 0.15}MnO{sub 3} single crystal

Energy Technology Data Exchange (ETDEWEB)

Naumov, S.V., E-mail: naumov@imp.uran.ru [Institute of Metal Physics, Ural Branch of RAS, Kovalevskaya Street 18, Ekaterinburg 620990 (Russian Federation); Loshkareva, N.N.; Mostovshchikova, E.V.; Solin, N.I.; Korolev, A.V.; Arbuzova, T.I.; Telegin, S.V.; Patrakov, E.I. [Institute of Metal Physics, Ural Branch of RAS, Kovalevskaya Street 18, Ekaterinburg 620990 (Russian Federation)

2013-01-01

Magnetic, transport and optical properties of the Ca{sub 0.85}Eu{sub 0.15}MnO{sub 3} single crystal are studied and discussed in comparison with the properties of polycrystalline sample. The magnetic data show existence the two magnetic phase transitions under cooling: the transition near 150 K occurs from the paramagnetic orthorhombic to C-type antiferromagnetic monoclinic phase with the charge/orbital ordering in some part of the crystal; and at 90 K the transition from the paramagnetic to G-type antiferromagnetic phase takes place in another part of the crystal with the orthorhombic structure. The magnetoresistance of the Ca{sub 0.85}Eu{sub 0.15}MnO{sub 3} single crystal has features at temperatures of these phase transitions. Differences in the properties of single crystal and polycrystalline sample with the same content of Eu are associated with the ordering of oxygen vacancies that appear under the crystal growth. The reflection spectra in infrared range confirm the existence of the electron conductivity in a narrow band at room temperature.

Passive Fe2+ : ZnSe single-crystal Q switch for 3-mu m lasers

NARCIS (Netherlands)

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

Passive Q-switching of 3-mu m lasers with the help of a Fe2+ : ZnSe single crystal is demonstrated. The 6-mJ, 50-ns giant pulses are obtained from a 2.9364-mu m Er : YAG laser by using this passive Q switch.

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.

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)

Pinning-to-barrier crossover in YBa2Cu3O7-δ single crystals

Science.gov (United States)

Indenbom, M. V.; van der Beek, C. J.; Berseth, V.; Konczykowski, M.; Holtzberg, F.; Benoit, W.

1996-03-01

The behaviour of magnetic flux in high purity untwinned YBa2Cu3O7-δ (YBCO) single crystals is visualised by means of the magneto-optical technique. It is observed that after zero field-cooling at high temperatures near T c , flux penetrates directly to the sample center over a flux free edge area, in contrast to the usual Bean-like flux penetration from the edges. This fact clearly shows that volume pinning becomes negligible compared with the edge barrier. The role of the recently rediscovered geometrical barrier in the crystal magnetisation is discussed.

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.

Optically stimulated luminescence of Tb{sup 3+}/Sm{sup 3+} doubly doped K{sub 2}YF{sub 5} single crystals

Energy Technology Data Exchange (ETDEWEB)

Camargo, L.; Marcazzo, J.; Santiago, M.; Caselli, E. [Universidad Nacional del Centro de la Provincia de Buenos Aires, Instituto de Fisica Arroyo Seco, Gral. Pinto 399, B7000GHG, Tandil (Argentina); Khaidukov, N. M., E-mail: jmarcass@exa.unicen.edu.ar [Kurnakov Institute of General and Inorganic Chemistry, RAS, Leninskii Prospekt 31, 119991 Moscow (Russian Federation)

2014-08-15

In this work optically stimulated luminescence (OSL) properties of K{sub 2}YF{sub 5} crystals doubly doped with Tb{sup 3+} and Sm{sup 3+} ions have been investigated for the first time. OSL responses for different dopant concentration and for optical stimulation with different wavelengths have been analyzed for each compound. Dosimetric properties of the most efficient composition, namely, K{sub 2}YF{sub 5}:1.0 at.% Tb{sup 3+}; 1.0 at.% Sm{sup 3+}, have been studied. Finally, the possible application of this single crystal as OSL dosimeter has been evaluated. (Author)

Synthesis, electronic transport and optical properties of Si:α-Fe2O3 single crystals

NARCIS (Netherlands)

Rettie, A.J.E.; Chemelewski, W.D.; Wygant, B.R.; Lindemuth, J.; Lin, J.F.; Eisenberg, D.; Brauer, C.S.; Johnson, T.J.; Beiswenger, T.N.; Ash, R.D.; Li, X.; Zhou, J.; Mullins, C.B.

2016-01-01

We report the synthesis of silicon-doped hematite (Si:alpha-Fe2O3) single crystals via chemical vapor transport, with Si incorporation on the order of 1019 cm(-3). The conductivity, Seebeck and Hall effect were measured in the basal plane between 200 and 400 K. Distinct differences in electron

Elaboration and characterization of a KCl single crystal doped with nanocrystals of a Sb2O3 semiconductor

International Nuclear Information System (INIS)

Bouhdjer, L.; Addala, S.; Halimi, O.; Boudine, B.; Sebais, M.; Chala, A.

2013-01-01

Undoped and doped KCl single crystals have been successfully elaborated via the Czochralski (Cz) method. The effects of dopant Sb 2 O 3 nanocrystals on structural and optical properties were investigated by a number of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDAX) analysis, UV-visible and photoluminescence (PL) spectrophotometers. An XRD pattern of KCl:Sb 2 O 3 reveals that the Sb 2 O 3 nanocrystals are in the well-crystalline orthorhombic phase. The broadening of diffraction peaks indicated the presence of a Sb 2 O 3 semiconductor in the nanometer size regime. The shift of absorption and PL peaks is observed near 334 nm and 360 nm respectively due to the quantum confinement effect in Sb 2 O 3 nanocrystals. Particle sizes calculated from XRD studies agree fairly well with those estimated from optical studies. An SEM image of the surface KCl:Sb 2 O 3 single crystal shows large quasi-spherical of Sb 2 O 3 crystallites scattered on the surface. The elemental analysis from EDAX demonstrates that the KCl:Sb 2 O 3 single crystal is slightly rich in oxygen and a source of excessive quantities of oxygen is discussed. (semiconductor materials)

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)

Controllable synthesis of rice-shape Alq3 nanoparticles with single crystal structure

Science.gov (United States)

Xie, Wanfeng; Fan, Jihui; Song, Hui; Jiang, Feng; Yuan, Huimin; Wei, Zhixian; Ji, Ziwu; Pang, Zhiyong; Han, Shenghao

2016-10-01

We report the controllable growth of rice-shape nanoparticles of Alq3 by an extremely facile self-assembly approach. Possible mechanisms have been proposed to interpret the formation and controlled process of the single crystal nanoparticles. The field-emission performances (turn-on field 7 V μm-1, maximum current density 2.9 mA cm-2) indicate the potential application on miniaturized nano-optoelectronics devices of Alq3-based. This facile method can potentially be used for the controlled synthesis of other functional complexes and organic nanostructures.

Laser excited fluorescence spectrum of Ho3+:SrF2 single crystal

International Nuclear Information System (INIS)

Lal, Bansi; Ramachandra Rao, D.

1980-01-01

The fluorescence spectrum of Ho 3+ : SrF 2 single crystal excited by the various lines of an Ar + laser, is reported. The three fluorescence groups recorded in the region 5300-7700 A, correspond to the transitions from ( 5 F 4 , 5 S 2 ) to 5 I 8 , 5 F 5 to 5 I 8 , 5 F 3 to 5 I 7 and ( 5 F 4 , 5 S 2 ) to 5 I 7 . Marked changes in the total integrated intensity of the various fluorescence groups with the change in the exciting wavelength are observed. (author)

Synthesis, crystal growth and characterization of bioactive material: 2- Amino-1H-benzimidazolium pyridine-3-carboxylate single crystal- a proton transfer molecular complex

Science.gov (United States)

Fathima, K. Saiadali; Kavitha, P.; Anitha, K.

2017-09-01

The 1:1 molecular adducts 2- Amino-1H-benzimidazolium pyridine-3-carboxylate (2ABPC) was synthesized and grown as single crystal where 2-aminobenzimidazole (ABI) acts as a donor and nicotinic acid (NA) acts as an acceptor. The presence of proton and carbon were predicted using 1H and 13C NMR spectral analysis. The molecular structure of the crystal was elucidated by subjecting the grown crystals to the single crystal x-ray diffraction analysis and was refined by full matrix least-squares method to R = 0.038 for 2469 reflections. The vibrational modes of functional group have been studied using FTIR and Raman spectroscopic analysis. The UV-Vis spectrum exhibited a visible band at 246 nm for 2ABPC due to the nicotinate anion of the molecule. Further, the antimicrobial activity of 2ABPC complex against B. subtilis, klebsiella pneumonia, Pseudomonas eruginos and E. coli pathogens was investigated. Minimum Inhibitory Concentration (MIC) for this crystal was obtained using UV spectrometer against MRSA pathogen. It was found that the benzimidazole with aminogroup at position 2 increases the general antimicrobial activities of 2ABPC crystal.

Structure of single-chain single crystals of isotactic polystyrene and their radiation resistance

International Nuclear Information System (INIS)

Bu Haishan; Cao Jie; Xu Shengyong; Zhang Ze

1997-01-01

The structure of the single-chain single crystals of isotactic polystyrene (i-PS) was investigated by electron diffraction (ED) and high resolution electron microscopy (HREM). The nano-scale single-chain single crystals were found to be very stable to electron irradiation. According to the unit cell of i-PS crystals, the reflection rings in ED pattern and the lattice fringes in HREM images could be indexed, but the lower-index diffractions were not found. It is proposed that the single-chain single crystals are very small, thus secondary electrons may be allowed to escape and radiation damage is highly reduced, and that there are less lower-index lattice planes in the single-chain single crystals to provide sufficient diffraction intensity for recording. HREM images can be achieved at room temperature in the case of single-chain single crystals because of its stability to electron irradiation, therefore, this might be a novel experimental approach to the study of crystal structure of macromolecules

Preparation of a Non-Polar ZnO Film on a Single-Crystal NdGaO3 Substrate by the RF Sputtering Method

Science.gov (United States)

Kashiwaba, Y.; Tanaka, Y.; Sakuma, M.; Abe, T.; Imai, Y.; Kawasaki, K.; Nakagawa, A.; Niikura, I.; Kashiwaba, Y.; Osada, H.

2018-04-01

Preparation of non-polar ZnO ( 11\\overline{2} 0 ) films on single-crystal NdGaO3 (NGO) (001) substrates was successfully achieved by the radio frequency (RF) sputtering method. Orientation, deposition rate, and surface roughness of ZnO films strongly depend on the working pressure. Characteristics of ZnO films deposited on single-crystal NGO (001) substrates were compared with those of ZnO films deposited on single-crystal sapphire ( 01\\overline{1} 2 ) substrates. An x-ray diffraction peak of the ZnO ( 11\\overline{2} 0 ) plane was observed on ZnO films deposited on single-crystal NGO (001) substrates under working pressure of less than 0.5 Pa. On the other hand, uniaxially oriented ZnO ( 11\\overline{2} 0 ) films on single-crystal sapphire ( 01\\overline{1} 2 ) substrates were observed under working pressure of 0.1 Pa. The mechanism by which the diffraction angle of the ZnO ( 11\\overline{2} 0 ) plane on single-crystal NGO (001) substrates was shifted is discussed on the basis of anisotropic stress of lattice mismatch. The deposition rate of ZnO films decreased with an increase in working pressure, and the deposition rate on single-crystal NGO (001) substrates was larger than that on single-crystal sapphire ( 01\\overline{1} 2 ) substrates. Root mean square (RMS) roughness of ZnO films increased with an increase in working pressure, and RMS roughness of ZnO films on single-crystal NGO (001) substrates was smaller than that of ZnO films on single-crystal sapphire ( 01\\overline{1} 2 ) substrates even though the film thickness on single-crystal NGO (001) substrates was greater than that on sapphire substrates. It is thought that a single-crystal NGO (001) substrate is useful for deposition of non-polar ZnO ( 11\\overline{2} 0 ) films.

Polarization-switching dynamics and microstructures of ferroelectric (Bi0.5Na0.5)TiO3 single crystals

Science.gov (United States)

Yanai, Ken; Onozuka, Hiroaki; Kitanaka, Yuuki; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro; Kurushima, Kousuke; Mori, Shigeo

2013-04-01

Single crystals of ferroelectric (Bi0.5Na0.5)TiO3 were successfully grown by using the top-seeded solution growth method at a high oxygen pressure of 0.9 MPa and their polarization switching dynamics along the c direction and their domain structures were investigated. Piezoelectric force microscope (PFM) observations show that BNT crystals poled along the c direction. had 71-degree domains in which the spontaneous polarization ( P s ) vector was opposite to the direction of the poling electric field. Synchrotron-radiation single-crystal X-ray diffraction analyses and PFM observations revealed that the polarization switching in the BNT crystals along the c direction was achieved by a 71-degree rotation of the P s vector.

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.

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 ...

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

Nd-doped Lu3Al5O12 single-crystal scintillator for X-ray imaging

International Nuclear Information System (INIS)

Sugiyama, Makoto; Fujimoto, Yutaka; Yanagida, Takayuki; Totsuka, Daisuke; Chani, Valery; Yokota, Yuui; Yoshikawa, Akira

2013-01-01

The optical and scintillation properties of Nd-doped Lu 3 Al 5 O 12 (Nd:LuAG) crystals grown by the Czochralski (Cz) method were examined under X-ray excitation. Their applicability for X-ray imaging was also inspected. The radioluminescence spectrum induced by X-rays showed a broad host emission and sharp Nd 3+ 4f–4f emission peaks in the UV to visible wavelengths. The light output current of the Nd:LuAG was 85% of that of a standard CdWO 4 X-ray scintillator. The afterglow value measured 20 ms after X-ray irradiation was 1.5%. An X-ray radiographic image was successfully obtained using the Nd:LuAG scintillator coupled with the charge coupled device (CCD) photodetector. -- Highlights: ► The Nd:LuAG single crystal was produced to perform X-ray imaging test. ► The sample exhibited the 85% light output current of the standard CdWO 4 . ► The afterglow intensity of the sample was very high compared with the CdWO 4 . ► The X-ray radiographic image was obtained from the Nd:LuAG single crystal

Nb3Sn single crystals, polycrystals and multifilamentary wires: common and different features in the magnetic response

International Nuclear Information System (INIS)

Adesso, M G; Uglietti, D; Fluekiger, R; Polichetti, M; Pace, S

2006-01-01

The magnetic response of different Nb 3 Sn samples has been investigated studying the temperature dependence of both the 1st and 3rd harmonics of the AC magnetic susceptibility, in presence of a DC field up to 19 T. In single crystal and in polycrystalline samples, the occurrence of a Peak Effect was observed within DC magnetic fields ranging from 3 T to about 13 T. It corresponds to a transition in the vortex lattice between the Bragg Glass phase and a disordered phase. This transition has been also detected at higher magnetic fields in both the samples, thanks to the 3rd harmonics measurements. In contrast to single crystals and polycrystals, no Peak Effect and no indications about the Bragg/disordered phase transition have been detected in the analysed multifilamentary wires

Characterization of Bi4Ge3O12 single crystal by impedance spectroscopy

Directory of Open Access Journals (Sweden)

Zélia Soares Macedo

2003-12-01

Full Text Available Bi4Ge3O12 (bismuth germanate - BGO single crystals were produced by the Czochralski technique and their electrical and dielectric properties were investigated by impedance spectroscopy. The isothermal ac measurements were performed for temperatures from room temperature up to 750 °C, but only the data taken above 500 °C presented a complete semicircle in the complex impedance diagrams. Experimental data were fitted to a parallel RC equivalent circuit, and the electrical conductivity was obtained from the resistivity values. Conductivity values from 5.4 × 10(9 to 4.3 × 10-7 S/cm were found in the temperature range of 500 to 750 °C. This electrical conductivity is thermally activated, following the Arrhenius law with an apparent activation energy of (1.41 ± 0.04 eV. The dielectric properties of BGO single crystal were also studied for the same temperature interval. Permittivity values of 20 ± 2 for frequencies higher than 10³ Hz and a low-frequency dispersion were observed. Both electric and dielectric behavior of BGO are typical of systems in which the conduction mechanism dominates the dielectric response.

Study of thermochemically reduced and electron-irradiated LiNbO3 single crystals by positron annihilation and optical absorption measurements

International Nuclear Information System (INIS)

Pareja, R.; Gonzalez, R.; Pedrosa, M.A.

1984-01-01

Irradiation of LiNbO 3 single crystals using Van de Graaff electrons with an energy of 1.5 MeV introduces an optical absorption band similar to that observed in thermochemically reduced samples. As-grown, reduced, or irradiated crystals show single-component positron lifetime spectra with an average decay time of 234 ps. (author)

Single Crystal Growth of Pure Co3+ Oxidation State Material LaSrCoO4

Directory of Open Access Journals (Sweden)

Hanjie Guo

2016-08-01

Full Text Available We report on the single crystal growth of the single-layer perovskite cobaltate LaSrCoO4 that was grown by the optical floating zone method using high oxygen pressures. Phase purity and single crystallinity were confirmed by X-ray diffraction techniques. The pure Co3+ oxidation state was confirmed by X-ray absorbtion spectroscopy measurements. A transition to a spin glass state is observed at ∼7 K in magnetic susceptibility and specific heat measurements.

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

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.

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)

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

Luminescence and light yield of (Gd2Y)(Ga3Al2)O12:Pr3+ single crystal scintillators

Science.gov (United States)

Lertloypanyachai, Prapon; Pathumrangsan, Nichakorn; Sreebunpeng, Krittiya; Pattanaboonmee, Nakarin; Chewpraditkul, Weerapong; Yoshikawa, Akira; Kamada, Kei; Nikl, Martin

2017-06-01

Praseodymium-doped (Gd2Y)(Ga3Al2)O12 (GYGAG: Pr) single crystals are grown by the micro-pulling down method with different Pr concentrations. The energy transfer process between Pr3+ and Gd3+ is investigated by photoluminescence excitation (PLE) and emission (PL) spectra measurements. Photoelectron yield measurements are carried out using photomultiplier. At 662 keV γ-rays, photoelectron yield of 2520 phe/MeV obtained for the GYGAG: Pr (0.01%) sample is larger than that of 1810 phe/MeV obtained for BGO crystal. Light yield degradation for the GYGAG: Pr scintillators is presumably due to the energy transfer from 5d state of Pr3+ to 4f state of Gd3+ together with the concentration quenching in the Gd3+-sublattice.

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.

Pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} on amorphous dielectric layers towards monolithic 3D photonic integration

Energy Technology Data Exchange (ETDEWEB)

Li, Haofeng; Brouillet, Jeremy; Wang, Xiaoxin; Liu, Jifeng, E-mail: Jifeng.Liu@dartmouth.edu [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States)

2014-11-17

We demonstrate pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} crystallized on amorphous layers at <450 °C towards 3D Si photonic integration. We developed two approaches to seed the lateral single crystal growth: (1) utilize the Gibbs-Thomson eutectic temperature depression at the tip of an amorphous GeSn nanotaper for selective nucleation; (2) laser-induced nucleation at one end of a GeSn strip. Either way, the crystallized Ge{sub 0.89}Sn{sub 0.11} is dominated by a single grain >18 μm long that forms optoelectronically benign twin boundaries with others grains. These pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} patterns are suitable for monolithic 3D integration of active photonic devices on Si.

Local coercive force of domain boundaries

International Nuclear Information System (INIS)

Kandaurova, G.S.; Vas'kovskij, V.O.

1980-01-01

The aim of the present paper is to show the variety of effects resulting from local coercivity using RFeO 3 orthoferrites crystals-plates, to separate factors which are not directly connected with the nature of every single defect but influence significantly Hsub(cw) local coercivity and, at last, to attract attention of physisists-theorists to new tasks of the magnetic hysteresis theory. Measurements have been carried out on a great number of defect of YFeO 3 and PyFeO 3 crystals. Such peculiarities of local coercivity as Hsub(cw) anisotropy and asymmetry, Hsub(cw) nonstability and its dependence on the sample magnetic prehistory. Qualitative explanation of these effects in based on the presumable interaction of the domain wall with magnetic heterogeneities existing in a region of structural defects

Anisotropic electrical properties of superconducting single crystals YBa2 Cu3 O7-x

International Nuclear Information System (INIS)

Konczykowski, M.; Rullier-Albenque, F.

1988-01-01

The effect of the hydrostatic pressure (up to 18 kbar) on the transport properties of YBa 2 Cu 3 O 7 single crystals was investigated. A decrease of the resistivity and of its anisotropy was observed under pressure whereas an increase of the critical temperature, of the upper critical field and of its slope vs temperature variation was found

Single crystal growth of 67%BiFeO3-33%BaTiO3 solution by the floating zone method

Science.gov (United States)

Rong, Y.; Zheng, H.; Krogstad, M. J.; Mitchell, J. F.; Phelan, D.

2018-01-01

The growth conditions and the resultant grain morphologies and phase purities from floating-zone growth of 67%BiFeO3-33%BaTiO3 (BF-33BT) single crystals are reported. We find two formidable challenges for the growth. First, a low-melting point constituent leads to a pre-melt zone in the feed-rod that adversely affects growth stability. Second, constitutional super-cooling (CSC), which was found to lead to dendritic and columnar features in the grain morphology, necessitates slow traveling rates during growth. Both challenges were addressed by modifications to the floating-zone furnace that steepened the temperature gradient at the melt-solid interfaces. Slow growth was also required to counter the effects of CSC. Single crystals with typical dimensions of hundreds of microns have been obtained which possess high quality and are suitable for detailed structural studies.

Single crystal growth of 67%BiFeO 3 -33%BaTiO 3 solution by the floating zone method

Energy Technology Data Exchange (ETDEWEB)

Rong, Y.; Zheng, H.; Krogstad, M. J.; Mitchell, J. F.; Phelan, D.

2018-01-01

The growth conditions and the resultant grain morphologies and phase purities from floating-zone growth of 67%BiFeO3-33%BaTiO3 (BF-33BT) single crystals are reported. We find two formidable challenges for the growth. First, a low-melting point constituent leads to a pre-melt zone in the feed-rod that adversely affects growth stability. Second, constitutional super-cooling (CSC), which was found to lead to dendritic and columnar features in the grain morphology, necessitates slow traveling rates during growth. Both challenges were addressed by modifications to the floating-zone furnace that steepened the temperature gradient at the melt-solid interfaces. Slow growth was also required to counter the effects of CSC. Single crystals with typical dimensions of hundreds of microns have been obtained which possess high quality and are suitable for detailed structural studies.

Features of the structural states of KNbO{sub 3} single crystals before and after fast-neutron irradiation

Energy Technology Data Exchange (ETDEWEB)

Stash, A. I., E-mail: astas@yandex.ru; Ivanov, S. A.; Stefanovich, S. Yu.; Mosunov, A. V.; Boyko, V. M.; Ermakov, V. S.; Korulin, A. V.; Kalyukanov, A. I. [State Scientific Center of the Russian Federation Karpov Institute of Physical Chemistry (Russian Federation)

2017-01-15

Neutron irradiation is a unique tool for forming new structural states of ferroelectrics, which cannot be obtained by conventional methods. The inf luence of the irradiation by two doses of fast neutrons (F = 1 × 10{sup 17} and 3 × 10{sup 17} cm{sup –2}) on the structure and properties of KNbO{sub 3} single crystals has been considered for the first time. The developed method for taking into account the experimental correction to the diffuse scattering has been used to analyze the structural changes occurring in KNbO{sub 3} samples at T = 295 K and their correlations with the behavior of dielectric and nonlinear optical characteristics. The irradiation to the aforementioned doses retains the KNbO{sub 3} polar structure, shifting Т{sub Ð}¡ to lower temperatures and significantly affecting only the thermal parameters and microstructure of single crystals. Neutron irradiation with small atomic displacements provides a structure similar to the high-temperature modification of an unirradiated KNbO{sub 3} crystal.

Pressure-induced effects on the spectroscopic properties of Nd{sup 3+} in MgO:LiNbO{sub 3} single crystal. A crystal field approach

Energy Technology Data Exchange (ETDEWEB)

Muñoz Santiuste, J.E., E-mail: jems@fis.uc3m.es [Departamento de Física, Escuela Politécnica Superior, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28913 Leganés, Madrid (Spain); MALTA Consolider Team (Spain); Lavín, V.; Rodríguez-Mendoza, U.R. [MALTA Consolider Team (Spain); Departamento de Física, INM and IUdEA, Universidad de La Laguna, Apdo. 456. E-38200 San Cristóbal de La Laguna, Santa Cruz de Tenerife (Spain); Tardio, M.M.; Ramírez-Jiménez, R. [Departamento de Física, Escuela Politécnica Superior, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28913 Leganés, Madrid (Spain)

2017-04-15

The effects of pressure on the Nd{sup 3+}-doped MgO:LiNbO{sub 3} single crystal have been studied by luminescence spectroscopy at low temperature and high pressures from ambient conditions up to 33 GPa. Specifically, the pressure-induced evolution of the emission spectra, corresponding to the {sup 4}F{sub 3/2}→{sup 4}I{sub 9/2},{sup 4}I{sub 11/2} transitions, and the excitation spectra, corresponding to the {sup 4}I{sub 9/2}→{sup 4}F{sub 5/2}+{sup 2}H{sub 9/2}, and {sup 4}I{sub 9/2}→{sup 4}F{sub 7/2}+{sup 4}S{sub 3/2} transitions, show a gradual red-shift that follows a linear pressure dependence and a decrease in the intensity of the spectra with increasing pressure. The initial effect of increasing pressure on the MgO:LiNbO{sub 3} crystal is the modification of the relative amount of the several centers in the sample. At pressures around 20 GPa the characteristic multicenter Nd{sup 3+} structure eventually disappears indicating that all the centers have very similar environments near this pressure. At higher pressures, observed changes seem to have a different origin. The evolution of Nd{sup 3+} luminescence is studied in the frame of crystal-field theory in order to evaluate its capability of monitoring the pressure-induced structural changes. Crystal-field analysis, under approximated C{sub 3v} symmetry, shows a smooth increase of the overall crystal-field strength on the luminescent ion, which can be related to the volume reduction as pressure increases. Crystal-field parameters also show a general monotonic behavior with pressure that indicates a structural modification of the local structure that, maintaining the trigonal symmetry around the impurity ion, evolves towards a lower axial character. No evidences of a phase transition have been observed in the studied pressure range.

Synthesis of single-crystal perovskite PbCrO3 through a new reaction route at high pressure

Science.gov (United States)

Han, Yunxia; Wang, Shanmin; Liu, Yinjuan; Ma, Dejiang; He, Duanwei; Zhao, Yusheng

2018-04-01

As a new member in the family of Mott system, perovskite PbCrO3 has recently been uncovered to exhibit fantastic structural transition under pressure, coupled with magnetic, electronic, and ferromagnetic transitions, which provide many opportunities for understanding of correlated system. However, it is still challenging to synthesize high-quality single-crystal PbCrO3, leading to the limited exploration of this Mott compound. In this work, we formulate a new high-pressure reaction route for preparation of high-quality PbCrO3 crystals between PbCl2 and Na2CrO4 at high pressure of 5-10 GPa and at high temperature of 750-1500°C. Because of the formation of reaction byproduct NaCl, the final product can readily be separated by washing with water. The obtained sample is in the form of single crystal with crystallite size up to 200 μm. In addition, combined with X-ray diffraction measurement, a tentative pressure-temperature synthesis diagram of PbCrO3 is mapped out from the reaction between PbCl2 and Na2CrO4 and the reaction mechanism is also explored in detail.

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

Crystal growth and scintillation properties of Er-doped Lu{sub 3}Al{sub 5}O{sub 12} single crystals

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, Makoto, E-mail: makoto.sugiyama@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Fujimoto, Yutaka [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yanagida, Takayuki [New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Totsuka, Daisuke [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Nihon Kessho Kogaku Co. Ltd., 810-5 Nobe-cho Tatebayashi Gunma (Japan); Kurosawa, Shunsuke; Futami, Yoshisuke; Yokota, Yuui; Chani, Valery [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yoshikawa, Akira [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)

2012-02-01

Er-doped Lu{sub 3}Al{sub 5}O{sub 12} (Er:LuAG) single crystalline scintillators with different Er concentrations of 0.1, 0.5, 1, and 3% were grown by the micro-pulling-down ({mu}-PD) method. The grown crystals were composed of single-phase material, as demonstrated by powder X-ray diffraction (XRD). The radioluminescence spectra measured under {sup 241}Am {alpha}-ray excitation indicated host emission at approximately 350 nm and Er{sup 3+} 4f-4f emissions. According to the pulse height spectra recorded under {gamma}-ray irradiation, the 0.5% Er:LuAG exhibited the highest peak channel among the samples. The {gamma}-ray excited decay time profiles were well fitted by the two-component exponential approximation (0.8 {mu}s and 6-10 {mu}s).

Defect structure of TiS{sub 3} single crystals of the A-ZrSe{sub 3} type

Energy Technology Data Exchange (ETDEWEB)

Bolotina, N. B., E-mail: nb-bolotina@mail.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics,” (Russian Federation); Gorlova, I. G. [Russian Academy of Sciences, Kotel’nikov Institute of Radioengineering and Electronics (Russian Federation); Verin, I. A. [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics,” (Russian Federation); Titov, A. N. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation); Arakcheeva, A. V. [Phase Solutions, Co Ltd. (Switzerland)

2016-11-15

The defect structure of TiS{sub 3} single crystals of the A-ZrSe{sub 3} type has been determined based on X-ray diffraction data. Shear defects manifest themselves as displacements of ab layers (which can imitate a twin) by ∼0.5a. Regular shears facilitate the formation of a superstructure along the c axis. A model of defect in the layer structure is proposed to explain the atomic displacements at an angle to the layer plane.

Controlled reduction and oxidation of La0.85Sr0.15MnO3 single crystals

International Nuclear Information System (INIS)

De Leon-Guevara, A.M.; Berthet, P.; Berthon, J.; Millot, F.; Revcolevschi, A.

1997-01-01

La 0.85 Sr 0.15 MnO 3 single crystals were grown by the floating zone method. They can be reversibly reduced under controlled oxygen partial pressure. Their defect chemistry is investigated together with the evolution of their cell parameters and that of their electric conductivity which is very sensitive to their oxygen content. On the other hand, stoichiometric crystals can be oxidized with a slow kinetics making possible the preparation of diphasic materials. (orig.)

Orientation dependence of dispersion and band gap of PIMNT single crystals

Science.gov (United States)

He, Chongjun; Chen, Hongbing; Wang, Jiming; Gu, Xiaorong; Wu, Tong; Liu, Youwen

2018-01-01

As piezoelectric materials, optical properties of xPb(In1/2Nb1/2)O3-(1-x-y)Pb(Mg1/3Nb2/3)O3-yPbTiO3 single crystals were not perfectly known. Here refractive indices and optical transmission of 0.25Pb(In1/2Nb1/2)O3-0.42Pb(Mg1/3Nb2/3)O3- 0.33PbTiO3 (PIMNT) single crystal are investigated after poled along different directions. Cauchy dispersion equations of the refractive indices were obtained by least square fitting, which can be used to calculate the refractive indices in the low absorption wavelength range. After poled along [011] direction, the optical transmission of PIMNT single crystal is more than 65% above 0.5 μm, which is much higher than that of [001] and [111] directions. Energy band gap was obtained from absorption coefficient.

X-ray and neutron single crystal diffraction on (NH4)3H(SO4)2. II. Refinement of crystal structure of phase II at room temperature

International Nuclear Information System (INIS)

Reehuis, M.; Wozniak, K.; Dominiak, P.; Smirnov, L.S.; Natkaniec, I.; Baranov, A.I.; Dolbinina, V.V.

2006-01-01

The (NH 4 ) 3 H(SO 4 ) 2 is of special interest due to the possible influence of ammonium ions on a series of phase transitions: I => II => III => IV => V => VII. Earlier, the X-ray single crystal diffraction study of phase II of (NH 4 ) 3 H(SO 4 ) 2 showed that the crystal structure of this compound has two crystallographically independent groups of ammonium ions NH 4 (1) and NH 4 (2), but orientational positions of these ammonium ions were not determined exactly. The refinement of NH 4 (1) and NH 4 (2) orientational positions in phase II is carried out with the help of the X-ray and neutron single crystal diffraction study. The analyses of differential Fourier maps of electron charge density and nuclear density point out the possibility of disordering of NH 4 (2) ammonium ions

Single crystal growth and low-temperature properties of Er{sub 3}Al{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Suttner, Christian; Benka, Georg; Bauer, Andreas; Pfleiderer, Christian [Physik Department, Technische Universitaet Muenchen, D-85748 Garching (Germany)

2016-07-01

In recent years, topologically non-trivial spin whirls in condensed matter systems attracted great scientific interest. Lattices of these objects, so-called magnetic skyrmion lattices, were mainly observed in Dzyaloshinskii-Moriya driven chiral magnets with the non-centrosymmetric cubic space group P2{sub 1}3. Similar spin textures, however, may in principle also arise in a large number of further compounds. We report single-crystal growth of Er{sub 3}Al{sub 2} crystallizing in the tetragonal space group P4{sub 2}/mnm by means of optical float zoning under UHV-compatible conditions. We determined the magnetic phase diagram for fields applied along different crystallographic directions using magnetization, ac susceptibility, and specific heat measurements. Several phase pockets are observed below the Neel temperature T{sub N} = 27 K, consistent with earlier reports.

Thermal formation of mesoporous single-crystal Co3O4 nano-needles and their lithium storage properties

KAUST Repository

Lou, Xiong Wen; Deng, Da; Lee, Jim Yang; Archer, Lynden A.

2008-01-01

In this work, we report the simple solid-state formation of mesoporous Co3O4 nano-needles with a 3D single-crystalline framework. The synthesis is based on controlled thermal oxidative decomposition and re-crystallization of precursor β-Co(OH)2 nano-needles. Importantly, after thermal treatment, the needle-like morphology can be completely preserved, despite the fact that there is a large volume contraction accompanying the process: β-Co(OH)2 → Co3O 4. Because of the intrinsic crystal contraction, a highly mesoporous structure with high specific surface area has been simultaneously created. The textual properties can be easily tailored by varying the annealing temperature between 200-400 °C. Interestingly, thermal re-crystallization at higher temperatures leads to the formation of a perfect 3D single-crystalline framework. Thus derived mesoporous Co3O4 nano-needles serve as a good model system for the study of lithium storage properties. The optimized sample manifests very low initial irreversible loss (21%), ultrahigh capacity, and excellent cycling performance. For example, a reversible capacity of 1079 mA h g-1 can be maintained after 50 cycles. The superior electrochemical performance and ease of synthesis may suggest their practical use in lithium-ion batteries. © The Royal Society of Chemistry 2008.

EPR study of gamma irradiated N-methyl taurine (C 3H 9NO 3S) and sodium hydrogen sulphate monohydrate (NaHSO 3·H 2O) single crystals

Science.gov (United States)

Yıldırım, İlkay; Karabulut, Bünyamin

2011-03-01

EPR study of gamma irradiated C 3H 9NO 3S and NaHSO 3.H 2O single crystals have been carried out at room temperature. There is one site for the radicals in C 3H 9NO 3S and two magnetically distinct sites for the radicals in NaHSO 3. The observed lines in the EPR spectra have been attributed to the species of SO3- and RH radicals for N-methyl taurine, and to the SO3- and OH radicals for sodium hydrogen sulfate monohydrate single crystals. The principal values of the g for SO3-, the hyperfine values of RH and OH proton splitting have been calculated and discussed.

Regio-Regular Oligo and Poly(3-hexyl thiophene): Precise Structural Markers from the Vibrational Spectra of Oligomer Single Crystals.

KAUST Repository

Brambilla, Luigi

2014-10-14

© 2014 American Chemical Society. In this work, we report a comparative analysis of the infrared and Raman spectra of octa(3-hexylthiophene) (3HT)8, trideca(3-hexylthiophene) (3HT)13, and poly(3-hexylthiophene) P3HT recorded in various phases, namely, amorphous, semicrystalline, polycrystalline and single crystal. We have based our analysis on the spectra of the (3HT)8 single crystal (whose structure has been determined by selected area electron diffraction) taken as reference and on the results of DFT calculations and molecular vibrational dynamics. New and precise spectroscopic markers of the molecular structures show the existence of three phases, namely: hairy (phase 1), ordered (phase 2), and disordered/amorphous (phase 3). Conceptually, the identified markers can be used for the molecular structure analysis of other similar systems.

Ultra-large single crystals by abnormal grain growth.

Science.gov (United States)

Kusama, Tomoe; Omori, Toshihiro; Saito, Takashi; Kise, Sumio; Tanaka, Toyonobu; Araki, Yoshikazu; Kainuma, Ryosuke

2017-08-25

Producing a single crystal is expensive because of low mass productivity. Therefore, many metallic materials are being used in polycrystalline form, even though material properties are superior in a single crystal. Here we show that an extraordinarily large Cu-Al-Mn single crystal can be obtained by abnormal grain growth (AGG) induced by simple heat treatment with high mass productivity. In AGG, the sub-boundary energy introduced by cyclic heat treatment (CHT) is dominant in the driving pressure, and the grain boundary migration rate is accelerated by repeating the low-temperature CHT due to the increase of the sub-boundary energy. With such treatment, fabrication of single crystal bars 70 cm in length is achieved. This result ensures that the range of applications of shape memory alloys will spread beyond small-sized devices to large-scale components and may enable new applications of single crystals in other metallic and ceramics materials having similar microstructural features.Growing large single crystals cheaply and reliably for structural applications remains challenging. Here, the authors combine accelerated abnormal grain growth and cyclic heat treatments to grow a superelastic shape memory alloy single crystal to 70 cm.

The high-pressure behavior of spherocobaltite (CoCO3): a single crystal Raman spectroscopy and XRD study

Science.gov (United States)

Chariton, Stella; Cerantola, Valerio; Ismailova, Leyla; Bykova, Elena; Bykov, Maxim; Kupenko, Ilya; McCammon, Catherine; Dubrovinsky, Leonid

2018-01-01

Magnesite (MgCO3), calcite (CaCO3), dolomite [(Ca, Mg)CO3], and siderite (FeCO3) are among the best-studied carbonate minerals at high pressures and temperatures. Although they all exhibit the calcite-type structure ({R}\\bar{3}{c}) at ambient conditions, they display very different behavior at mantle pressures. To broaden the knowledge of the high-pressure crystal chemistry of carbonates, we studied spherocobaltite (CoCO3), which contains Co2+ with cation radius in between those of Ca2+ and Mg2+ in calcite and magnesite, respectively. We synthesized single crystals of pure spherocobaltite and studied them using Raman spectroscopy and X-ray diffraction in diamond anvil cells at pressures to over 55 GPa. Based on single crystal diffraction data, we found that the bulk modulus of spherocobaltite is 128 (2) GPa and K' = 4.28 (17). CoCO3 is stable in the calcite-type structure up to at least 56 GPa and 1200 K. At 57 GPa and after laser heating above 2000 K, CoCO3 partially decomposes and forms CoO. In comparison to previously studied carbonates, our results suggest that at lower mantle conditions carbonates can be stable in the calcite-type structure if the radius of the incorporated cation(s) is equal or smaller than that of Co2+ (i.e., 0.745 Å).

Effect of neutron irradiation on single crystal V3Si

International Nuclear Information System (INIS)

Viswanathan, R.; Caton, R.; Cox, D.E.; Guha, A.; Sarachik, M.P.; Smith, F.W.; Testardi, L.R.

1977-01-01

We We have investigated the effect of successive neutron irradiation up to a fluence of approximately 2 x 10 19 n/cm 2 , by measurements of heat capacity, susceptibility, resistivity, acoustic velocity and neutron diffraction in a single crystal V 3 Si. We find that for low level doses (phi t greater than or equal to 3.5 x 10 18 n/cm 2 ) (a) the structural transformation is very sensitive, whereas the suerconducting transition temperature, T/sub c/, is hardly affected, and (b) except for low temperature heat capacity, most of the other measurements show very little change. For the highest fluence of 2 x 10 19 n/cm 2 used to date, the T/sub c/ dropped to 7.5 K with large changes in the linear heat capacity coefficient, magnetic susceptibility and sound velocity. These results are discussed briefly in this paper

Isotopically pure single crystal epitaxial diamond films and their preparation

International Nuclear Information System (INIS)

Banholzer, W.F.; Anthony, T.R.; Williams, D.M.

1992-01-01

The present invention is directed to the production of single crystal diamond consisting of isotopically pure carbon-12 or carbon-13. In the present invention, isotopically pure single crystal diamond is grown on a single crystal substrate directly from isotopically pure carbon-12 or carbon-13. One method for forming isotopically pure single crystal diamond comprises the steps of placing in a reaction chamber a single substrate heated to an elevated diamond forming temperature. Another method for forming isotopically pure single crystal diamond comprises diffusing isotopically pure carbon-12 or carbon-13 through a metallic catalyst under high pressure to a region containing a single crystal substrate to form an isotopically pure single crystal diamond layer on said single crystal substrate

Three-dimensional oriented attachment growth of single-crystal pre-perovskite PbTiO3 hollowed fibers

KAUST Repository

Zhao, Ruoyu; Li, Ming; Ren, Zhaohui; Zhu, Yihan; Han, Gaorong

2017-01-01

Hollowed single-crystal pre-perovskite PbTiO fibers (PP-PTF) were successfully synthesized via a polyvinyl alcohol (PVA) assisted hydrothermal process. The as-prepared PP-PTF were characterized to be 0.3-1 μm in diameter and tens of micrometers

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)

Ultralow Self-Doping in 2D Hybrid Perovskite Single Crystals

KAUST Repository

Peng, Wei; Yin, Jun; Ho, Kang-Ting; Ouellette, Olivier; de Bastiani, Michele; Banavoth, Murali; El Tall, Omar; Shen, Chao; Miao, Xiaohe; Pan, Jun; Alarousu, Erkki; He, Jr-Hau; Ooi, Boon S.; Mohammed, Omar F.; Sargent, Edward H.; Bakr, Osman

2017-01-01

-processed semiconductors, including hybrid perovskites, which are usually high in defects due to rapid crystallization. Here, we uncover extremely low self-doping concentrations in single crystals of (C6H5C2H4NH3)2PbI4･(CH3NH3PbI3)n-1 (n=1, 2, and 3)—over three orders

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

Optical energy gaps and photoluminescence peaks of BaGa{sub 2}S{sub 4}:Er{sup 3+} and BaGa{sub 2}Se{sub 4}:Er{sup 3+} single crystals

Energy Technology Data Exchange (ETDEWEB)

Choe, Sung-Hyu [Chosun University, Kwangju (Korea, Republic of); Jin, Moon-Seog [Dongshin University, Naju (Korea, Republic of); Kim, Wha-Tek [Chonnam National University, Kwangju (Korea, Republic of)

2005-12-15

BaGa{sub 2}S{sub 4}:Er{sup 3+} and BaGa{sub 2}Se{sub 4}:Er{sup 3+} single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the BaGa{sub 2}S{sub 4}:Er{sup 3+} and the BaGa{sub 2}Se{sub 4}:Er{sup 3+} single crystals were found to be 4.045 eV and 3.073 eV, respectively, at 11 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Sharp emission peaks were observed in the photoluminescence spectra of the single crystals and assigned to radiation recombination between split Stark levels of the Er{sup 3+} ion.

Thermal conductivity of Ca3Co2O6 single crystals

Science.gov (United States)

Che, H. L.; Shi, J.; Wu, J. C.; Rao, X.; Liu, X. G.; Zhao, X.; Sun, X. F.

2018-05-01

Ca3Co2O6 is a rare example of one-dimensional Ising spin-chain material with the moments preferentially aligned along the c axis. In this work, we study the c-axis thermal conductivity (κc) of Ca3Co2O6 single crystal at low temperatures down to 0.3 K and in magnetic fields up to 14 T. The zero-field κc(T) shows a large phonon peak and can be well fitted by using the classical Debye model, which indicates that the heat transport is purely phononic. Moreover, the low-T κc(H) isotherms with H || c display a field-independent behavior. These results indicate that there is no contribution of magnetic excitations to the thermal conductivity in Ca3Co2O6, neither carrying heat nor scattering phonons, which can be attributed to the Ising-like spin anisotropy.

Optical and magnetic spectroscopy of rare-earth-doped yttrium aluminium borate (YAl sub 3 (BO sub 3) sub 4) single crystals

CERN Document Server

Watterich, A; Borowiec, M T; Zayarnyuk, T; Szymczak, H; Beregi, E; Kovács, L G

2003-01-01

For Ce sup 3 sup + , Er sup 3 sup + and Yb sup 3 sup + ions, electron paramagnetic resonance (EPR) spectra typical for S' = 1/2 ions are measured for YAl sub 3 (BO sub 3) sub 4 (YAB) single crystal. The spectra show axial symmetry indicating that all three dopants replace Y sup 3 sup + at the given dopant concentration. Corresponding g-tilde - and hyperfine A-tilde -tensors are determined. The EPR linewidth of Ce broadens with increasing temperature due to an Orbach relaxation process. Fitting the curve with an exponential, the energy difference is found to be equal to 270 +- 16 cm sup - sup 1. The optical absorption and excitation spectra of Ce in YAB single crystal measured at 300 K are similar to those found for polycrystalline materials. High-resolution polarized emission from the lowest excited to the sup 2 F sub 5 sub / sub 2 ground state, measured at 4.2 K, indicates a splitting of the ground state into three levels. The second level is located 277 +- 18 cm sup - sup 1 above the first one, in excellent...

Large piezoelectricity in electric-field modified single crystals of SrTiO3

Science.gov (United States)

Khanbabaee, B.; Mehner, E.; Richter, C.; Hanzig, J.; Zschornak, M.; Pietsch, U.; Stöcker, H.; Leisegang, T.; Meyer, D. C.; Gorfman, S.

2016-11-01

Defect engineering is an effective and powerful tool to control the existing material properties and produce completely new ones, which are symmetry-forbidden in a defect-free crystal. For example, the application of a static electric field to a single crystal of SrTiO3 forms a strained near-surface layer through the migration of oxygen vacancies out of the area beneath the positively charged electrode. While it was previously shown that this near-surface phase holds pyroelectric properties, which are symmetry-forbidden in centrosymmetric bulk SrTiO3, this paper reports that the same phase is strongly piezoelectric. We demonstrate the piezoelectricity of this phase through stroboscopic time-resolved X-ray diffraction under alternating electric field and show that the effective piezoelectric coefficient d33 ranges between 60 and 100 pC/N. The possible atomistic origins of the piezoelectric activity are discussed as a coupling between the electrostrictive effect and spontaneous polarization of this near-surface phase.

Ferroelectric domain structures in -oriented K0.15Na0.85NbO3 lead-free single crystal

Directory of Open Access Journals (Sweden)

Yan Chen

2015-03-01

Full Text Available In this work, ferroelectric domain structures of -oriented K0.15Na0.85NbO3 single crystal are characterized. Transmission electron microscopy (TEM observation revealed high-density of laminate domain structures in the crystal and the lattices of the neighboring domains are found to be twisted in a small angle. Superlattice diffraction spots of 1 2 { eeo } and 1 2 { ooe } in electron diffraction patterns are observed in the crystal, revealing the a+a+c− tilting of oxygen octahedral in the perovskite structure. The piezoresponse of domains and in-situ poling responses of K0.15Na0.85NbO3 crystal are observed by piezoresponse force microscopy (PFM, and the results assure its good ferroelectric properties.

Reshock and release response of aluminum single crystal

International Nuclear Information System (INIS)

Huang, H.; Asay, J. R.

2007-01-01

Reshock and release experiments were performed on single crystal aluminum along three orientations and on polycrystalline 1050 aluminum with 50 μm grain size at shock stresses of 13 and 21 GPa to investigate the mechanisms for previously observed quasielastic recompression behavior. Particle velocity profiles obtained during reshocking both single crystals and polycrystalline aluminum from initial shock stresses of 13-21 GPa show similar quasielastic recompression behavior. Quasielastic release response is also observed in all single crystals, but the magnitude of the effect is crystal orientation dependent, with [111] and [110] exhibiting more ideal elastic-plastic release for unloading from the shocked state than for the [100] orientation and polycrystalline aluminum. The quasielastic response of 1050 aluminum is intermediate to that of the [100] and [111] orientations. Comparison of the wave profiles obtained for both unloading and reloading of single crystals and polycrystalline 1050 aluminum from shocked states suggests that the observed quasielastic response of polycrystalline aluminum results from the averaging response of single crystals for shock propagation along different orientations, and that the response of 1050 aluminum with large grain boundaries is not significantly different from the results obtained on single crystal aluminum. The yield strength of the single crystals and 1050 aluminum is found to increase with shock stress, which is consistent with previous results [H. Huang and I. R. Asay, J. Appl. Phys. 98, 033524 (2005)

Large rotating field entropy change in ErFeO3 single crystal with angular distribution contribution

Science.gov (United States)

Huang, Ruoxiang; Cao, Shixun; Ren, Wei; Zhan, Sheng; Kang, Baojuan; Zhang, Jincang

2013-10-01

We report the rotating field entropy of ErFeO3 single-crystal in a temperature range of 3-40 K. The giant magnetic entropy change, ΔSM = -20.7 J/(kg K), and the refrigerant capacity, RC = 273.5 J/kg, are observed near T =6 K. The anisotropic constants at 6 K, K1 = 1.24× 103 J/kg, K2 = 0.74 × 103 J/kg, in the bc plane are obtained. By considering the magnetocrystalline anisotropy and Fermi-Dirac angular distribution along the orientation of spontaneous magnetization, the experimental results can be well simulated. Our present work demonstrates that ErFeO3 crystal may find practical use for low temperature anisotropic magnetic refrigeration.

Single crystal growth and structural evolution across the 1st order valence transition in (Pr1-yYy)1-xCaxCoO3-δ

Science.gov (United States)

Schreiber, N. J.; Zhang, Junjie; Zheng, Hong; Freeland, J. W.; Chen, Yu-Sheng; Mitchell, J. F.; Phelan, D.

2017-10-01

Praseodymium-containing cobalt perovskites, such as (Pr1-yYy)1-xCaxCoO3-δ, have been argued to undergo a first-order charge shift between Pr and hybridized Co-O orbitals that leads to a metal-insulator transition at a temperature, TVT. Magnetization and x-ray absorption spectroscopy measurements on single crystals of (Pr0.85Y0.15)0.7Ca0.3CoO3-δ grown in an IR image furnace under 40-60 bar of oxygen confirm the presence of this valence transition. Single crystal x-ray synchrotron diffraction measurements are consistent with an isomorphic phase transition at TVT. No evidence of charge ordering was revealed by the single crystal diffraction. Dissimilar to analytical transmission electron microscopy measurements performed on a grain from a polycrystalline sample that revealed an oxygen vacancy order-disorder transition at TVT, the present single-crystal measurements did not evidence such a transition, likely reflecting a lower density of oxygen vacancies in the high-pO2 grown single crystals.

Timing characteristics of Ce doped Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12} single crystals in comparison with CsI(Tl) scintillators

Energy Technology Data Exchange (ETDEWEB)

Tyagi, M.; Singh, A.K.; Singh, S.G.; Sen, S.; Gadkari, S.C. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India); Desai, V.V.; Nayak, B.K. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India)

2015-10-15

Single crystals of Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:Ce with B codopants were successfully grown using the Czochralski technique. The timing characteristics of the crystal was measured by coupling the crystal to photomultiplier tubes (PMT) or silicon photodiodes [Si(PIN)]. The two prompt γ-rays emitted in a cascade from {sup 60}Co or {sup 22}Na source were detected in coincidence using Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:Ce,B crystal detectors and a BaF{sub 2} detector. The time resolution of these crystals are observed to be better than that measured for CsI:Tl crystal coupled to PMT or Si(PIN) in an identical measurement setup. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Growth and physicochemical properties of organometallic (DL)-trithioureatartrato-O1,O2,O3-cadmium(II) single crystals

Science.gov (United States)

Sathyamoorthy, K.; Vinothkumar, P.; Irshad Ahamed, J.; Murali Manohar, P.; Priya, M.; Liu, Jinghe

2018-04-01

Single crystals of organometallic (DL)-trithioureatartrato-O1,O2,O3-cadmium(II) (TUDLC) have been grown from methanol solution by using the slow evaporation of solvent growth technique. The lattice structure and crystalline perfection have been determined by carrying out single crystal X-ray diffraction and high resolution X-ray diffraction measurements. The grown crystal was characterized thermally and mechanically by carrying out thermo-gravimetric and micro hardness measurements. The linear and nonlinear optical characterizations were made by carrying out optical transmittance, surface laser damage threshold, particle size-dependent second harmonic generation (SHG) efficiency and photo conductivity measurements. The grown crystal was electrically characterized by carrying out frequency-dependent dielectric measurements. Chemical etching study was also carried out and the dislocation density was estimated. Results obtained in the present study indicate that the grown TUDLC crystal is optically transparent with lower cut-off wavelength 304 nm, mechanically soft, thermally stable up to 101 °C and NLO active with SHG efficiency 2.13 (in KDP unit). The grown crystal is found to have considerably large size, good crystalline perfection, large specific heat capacity, higher surface laser damage threshold and negative photoconductivity.

Low trap-state density and long carrier diffusion in organolead trihalide perovskite single crystals

KAUST Repository

Shi, Dong

2015-01-29

The fundamental properties and ultimate performance limits of organolead trihalide MAPbX3(MA = CH3NH3 +; X = Br- or I- ) perovskites remain obscured by extensive disorder in polycrystalline MAPbX3 films. We report an antisolvent vapor-assisted crystallization approach that enables us to create sizable crack-free MAPbX3 single crystals with volumes exceeding 100 cubic millimeters. These large single crystals enabled a detailed characterization of their optical and charge transport characteristics.We observed exceptionally low trap-state densities on the order of 109 to 1010 per cubic centimeter in MAPbX3 single crystals (comparable to the best photovoltaic-quality silicon) and charge carrier diffusion lengths exceeding 10 micrometers. These results were validated with density functional theory calculations.

Low trap-state density and long carrier diffusion in organolead trihalide perovskite single crystals

KAUST Repository

Shi, Dong; Adinolfi, Valerio; Comin, Riccardo; Yuan, Mingjian; Alarousu, Erkki; Buin, Andrei K.; Chen, Yin; Hoogland, Sjoerd H.; Rothenberger, Alexander; Katsiev, Khabiboulakh; Losovyj, Yaroslav B.; Zhang, Xin; Dowben, Peter A.; Mohammed, Omar F.; Sargent, E. H.; Bakr, Osman

2015-01-01

The fundamental properties and ultimate performance limits of organolead trihalide MAPbX3(MA = CH3NH3 +; X = Br- or I- ) perovskites remain obscured by extensive disorder in polycrystalline MAPbX3 films. We report an antisolvent vapor-assisted crystallization approach that enables us to create sizable crack-free MAPbX3 single crystals with volumes exceeding 100 cubic millimeters. These large single crystals enabled a detailed characterization of their optical and charge transport characteristics.We observed exceptionally low trap-state densities on the order of 109 to 1010 per cubic centimeter in MAPbX3 single crystals (comparable to the best photovoltaic-quality silicon) and charge carrier diffusion lengths exceeding 10 micrometers. These results were validated with density functional theory calculations.

Growth and spectroscopic properties of Yb{sup 3+}-doped Li{sub 6}Y(BO{sub 3}){sub 3} single crystal

Energy Technology Data Exchange (ETDEWEB)

Brenier, A. [Laboratoire de Physico-Chimie des Materiaux Luminescents, UMR CNRS no 5620, Universite Claude Bernard-Lyon1, 10 rue Ampere, 69622 Villeurbanne (France)]. E-mail: brenier@pcml.univ-lyon1.fr; Yoshikawa, A. [Institute of Multidisciplinary for Advanced Materials, Tohoku University, Sendai 980 8577 (Japan); Lebbou, K. [Laboratoire de Physico-Chimie des Materiaux Luminescents, UMR CNRS no 5620, Universite Claude Bernard-Lyon1, 10 rue Ampere, 69622 Villeurbanne (France); Jouini, A. [Laboratoire de Physico-Chimie des Materiaux Luminescents, UMR CNRS no 5620, Universite Claude Bernard-Lyon1, 10 rue Ampere, 69622 Villeurbanne (France); Institute of Multidisciplinary for Advanced Materials, Tohoku University, Sendai 980 8577 (Japan); Aloui-Lebbou, O. [Laboratoire de Physico-Chimie des Materiaux Luminescents, UMR CNRS no 5620, Universite Claude Bernard-Lyon1, 10 rue Ampere, 69622 Villeurbanne (France); Boulon, G. [Laboratoire de Physico-Chimie des Materiaux Luminescents, UMR CNRS no 5620, Universite Claude Bernard-Lyon1, 10 rue Ampere, 69622 Villeurbanne (France); Institute of Multidisciplinary for Advanced Materials, Tohoku University, Sendai 980 8577 (Japan); Fukuda, T. [Institute of Multidisciplinary for Advanced Materials, Tohoku University, Sendai 980 8577 (Japan)

2007-10-15

The spectroscopic properties of high-quality Czochralski grown 20% Yb{sup 3+}-doped Li{sub 6}Y(BO{sub 3}){sub 3} single crystal as new promising laser material are presented. The crystal was seeded-grown in the <0 1 0> direction and its crystallinity was measured using X-ray rocking curve analysis. Low temperature transmission spectrum exhibits broad bands in a short range of wavelengths and two sharp lines at 972.5 and 978 nm, interpreted as two zero-lines of two nonequivalent Yb{sup 3+} centers inside the lattice. The fluorescence lifetimes associated to these two intense lines are different: 0.867 and 1.33 ms. An attempt of determination of the Stark sublevels energies of the {sup 4}F{sub 5/2} and {sup 4}F{sub 7/2} manifolds of the two Yb{sup 3+} nonequivalent ions is given. The polarized absorption and emission spectra were also recorded at room temperature and we conclude that the most favorable emission line for laser application could be around 1042 nm in n {sub g} polarization.

Preparation of rod-like β-Si3N4 single crystal particles

International Nuclear Information System (INIS)

Hirao, K.; Tsuge, A.; Brito, M.E.; Kanzaki, S.

1994-01-01

The use of β-Si 3 N 4 particles as a seed material has been demonstrated to be effective for development of a self-reinforcing microstructure in sintered silicon nitride ceramics. We have confirmed the seeding effect and arrived at a concept that seed particles should consist of rod-like single crystals free from defects and with a large diameter. The present work describes our attempts to produce such particles with a controlled morphology and in high amount. β-Si 3 N 4 particles with a diameter of 1μm and length of 5μm were obtained by heating a mixture of α-Si 3 N 4 , SiO 2 and Y 2 O 3 , followed by acid rinse treatments to remove residual glassy phase. (orig.)

Magnetic properties of Co 2 2+ Co 1 - x 3+ Fe x 3+ BO5 ( x = 0.10) single crystals with a ludwigite structure

Science.gov (United States)

Knyazev, Yu. V.; Kazak, N. V.; Bayukov, O. A.; Platunov, M. S.; Velikanov, D. A.; Bezmaternykh, L. N.; Ivanova, N. B.; Ovchinnikov, S. G.

2017-04-01

The investigation of mixed Co-Fe ludwigite single crystals shows that their magnetic properties are close to the magnetic properties of Fe3BO5 despite the predominance of cobalt ions. The magnetic properties of Co3 - x Fe x BO5 single crystals with x = 0.10 are studied in detail. Magnetometric measurements demonstrate a strong magnetic anisotropy with easy magnetization axis b, and the orbital magnetic moment of cobalt is in a frozen state. The detected temperature dependence of the absorption of Mössbauer spectra allowed us to determine the magnetic ordering temperature, which agrees with the results of magnetization measurements ( T C = 84 K).

Atomistic simulations of displacement cascades in Y2O3 single crystal

International Nuclear Information System (INIS)

Dholakia, Manan; Chandra, Sharat; Valsakumar, M.C.; Mathi Jaya, S.

2014-01-01

Graphical abstract: (a) The averaged distortion index and the Y–O bond length of the Y 2 O 3 octahedra as a function of the simulation time for 5 keV PKA. (b) Shows the nearest neighbourhood of one of the Y ions as a function of simulation time, showing the destruction and the recovery of the YO 6 octahedron during the cascade corresponding to 5 keV Y PKA. - Highlights: • Qualitative difference in displacement cascades exists for Y and O PKA. • Nearest neighbour correlation between Y and O ions exists even at cascade peak. • Cascade core in Y 2 O 3 does not undergo melting. • Topological connectivity of YO 6 polyhedra plays important role in stability of Y 2 O 3 . - Abstract: We study the characteristics of displacement cascades in single crystal Y 2 O 3 using classical molecular dynamics. There are two possible ways to generate the cascades in yttria, using either the Y or the O atoms as the primary knock-on (PKA) atom. It is shown that there is a qualitative difference in the characteristics of the cascades obtained in these two cases. Even though the crystal is seen to be in a highly disordered state in the cascade volume, as seen from the plots of radial distribution function, the correlation between the Y and O atoms is not completely lost. This facilitates a quick recovery of the system during the annealing phase. Topological connectivity of the YO 6 polyhedral units plays an important role in imparting stability to the Y 2 O 3 crystal. These characteristics of the cascades can help explain the stability of the yttria nanoparticles when they are dispersed in oxide dispersion strengthened steels

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.

Spin-State Transition in La1-xSrxCoO3 Single Crystals

Science.gov (United States)

Bhardwaj, S.; Prabhakaran, D.; Awasthi, A. M.

2011-07-01

We present a study of the thermal conductivity (κ), specific heat (Cp) and Raman spectra of La1-xSrxCoO3 (x = 0,0.1) single crystals. Both the specimens have low thermal conductivity and board Raman peaks, arising from strong scattering of phonons by lattice disorder, produced by (and doping-enhanced) spin-states admixture of the Co3+ ions. The thermal conductivity anomalously deviates from ˜1/T behaviour at high (room) temperatures, expected of an insulator. High-temperature specific heat reveals large decrease in the metal-insulator (M-I) transition temperature with Sr-doping.

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.

Specific heat studies of pure Nb3Sn single crystals at low temperature

International Nuclear Information System (INIS)

Escudero, R; Morales, F; Bernes, S

2009-01-01

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

Growth, mechanical, and magnetic study of SmFeO{sub 3} single crystal grown by optical floating zone technique

Energy Technology Data Exchange (ETDEWEB)

Babu, P. Ramesh [Centre for Crystal Growth, VIT University, Vellore, Tamil Nadu (India); Bhaumik, Indranil [Crystal Growth Laboratory, Laser Materials Development and Devices Division, RRCAT, Indore (India); Ganesamoorthy, S. [Material Science Group, IGCAR, Kalpakkam, Tamil Nadu (India); Kalainathan, S., E-mail: kalainathan@yahoo.com [Centre for Crystal Growth, VIT University, Vellore, Tamil Nadu (India); Bhatt, R.; Karnal, A.K.; Gupta, P.K. [Crystal Growth Laboratory, Laser Materials Development and Devices Division, RRCAT, Indore (India)

2016-08-15

Single crystals of Samarium orthoferrite (SmFeO{sub 3}) have been grown by the optical floating zone technique. The growth parameters to yield good quality crystals are 5 mm/h for pulling and 30–40 rpm for rotation. The mechanical behavior of the grown crystal has been investigated. Rosette pattern has been observed around the indentation and the microhardness has been found to decreases non-linearly with the applied load. For load higher than 1.96 N there is a transition from palmqvist to median crack due to plastic deformation of the crystal. The hardness parameters like fracture toughness, brittleness index, and yield strength have also been calculated for palmqvist and median cracks occurring on the crystal surface. The magnetic investigations revealed that a magnetic transition in the range of 300–180 K. Above 180 K, the magnetization decreases as Sm and Fe sublattices have opposite spins. At high temperature, two anomalies are observed, one due to near spin reorientation (T{sub SR} = 480 K) and the other is AFM to paramagnetic transitions (T{sub N} = 670 K). The M–H curves exhibit a shape change with temperature due to the emergence and enlargement of multi-domain state of the SmFeO{sub 3} crystals. Bloch parameter (3.28 × 10{sup −5} K{sup −3/2}) has also been evaluated. - Highlights: • SmFeO{sub 3} single crystals have been grown by OFZ technique in air. • The microhardness has been found to decreases non-linearly with the applied load. • At 472 K, spin reorientation occurs in Fe sublattice. • The M–H curves exhibit a shape change with temperature due to the emergence and enlargement of multi-domain state. • Bloch 3/2-law holds good for SmFeO{sub 3} (B-parameter as 3.28 × 10{sup −5} K{sup −3/2}).

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

Science.gov (United States)

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

2016-03-01

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

Rise and fall of ferromagnetism in O-irradiated Al{sub 2}O{sub 3} single crystals

Energy Technology Data Exchange (ETDEWEB)

Li, Qiang [State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei 230026 (China); China Spallation Neutron Source, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803 (China); Xu, Juping; Liu, Jiandang; Du, Huaijiang; Ye, Bangjiao, E-mail: bjye@ustc.edu.cn [State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei 230026 (China)

2015-06-21

In dilute magnetic semiconductors studies, sapphire was usually used as non-magnetic substrate for films. We observed weak ferromagnetic component in Al{sub 2}O{sub 3} single crystal substrate, and excluded the possibility of ferromagnetic contaminations carefully by inductively coupled plasma mass spectrometry and X-ray photoelectron spectroscopy. The ferromagnetism rise and fall during the process of annealing-oxygen irradiation-annealing of the sapphire. The ferromagnetic changes are consistent with Al-vacancy related defects detected by positron annihilation spectroscopy. With first-principle calculations, we confirm that Al-vacancy can introduce magnetic moment for 3 μB in Al{sub 2}O{sub 3} crystal and form stable V{sub Al}-V{sub Al} ferromagnetic coupling at room temperature.

Controlled growth of filamentary crystals and fabrication of single-crystal whisker probes

International Nuclear Information System (INIS)

Givargizov, E. I.

2006-01-01

The growth of filamentary crystals (whiskers) on a single-crystal substrate through the vapour-liquid-solid mechanism is described. The possibility of fabricating oriented systems of whiskers on the basis of this mechanism of crystal growth is noted. A phenomenon that is important for nanotechnology is noted: the existence of a critical diameter of whiskers, below which they are not formed. The phenomenon of radial periodic instability, which is characteristic of nanowhiskers, is described and the ways of its elimination are shown. The possibility of transforming whiskers into single-crystal tips and the growth of crystalline diamond particles at their apices are noted as important for practice. Possible applications of systems of whiskers and tips are described briefly. Particular attention is paid to the latest direction in whisker technology-fabrication of single-crystal whisker probes for atomic force microscopy

Crystal structure and magnetic susceptibility of UOSe single crystals

International Nuclear Information System (INIS)

Kaczorowski, D.; Muenster Univ.; Poettgen, R.; Jeitschko, W.; Gajek, Z.; Zygmunt, A.

1993-01-01

The crystal structure and magnetic susceptibility behaviour of UOSe single crystals have been studied. UOSe crystalizes in the tetragonal PbFC1-type structure (space group P4/nmm) with the lattice parameters: a = 390.38(5) pm and c = 698.05(9) pm. It orders antiferromagnetically at T N =100±2 K and exhibits a very strong anisotropy in the susceptibility vs temperature variation. The magnetic and thermodynamic properties of UOSe are successfully interpreted in the framework of a perturbative ab initio crystal field approach. (Author)

Crystal structure and magnetic susceptibility of UOSe single crystals

Energy Technology Data Exchange (ETDEWEB)

Kaczorowski, D. (Polish Academy of Sciences, Wroclaw (Poland). Inst. for Low Temperature and Structure Research Muenster Univ. (Germany). Anorganisch-Chemisches Inst.); Poettgen, R.; Jeitschko, W. (Muenster Univ. (Germany). Anorganisch-Chemisches Inst.); Gajek, Z.; Zygmunt, A. (Polish Academy of Sciences, Wroclaw (Poland). Inst. for Low Temperature and Structure Research)

1993-01-01

The crystal structure and magnetic susceptibility behaviour of UOSe single crystals have been studied. UOSe crystalizes in the tetragonal PbFC1-type structure (space group P4/nmm) with the lattice parameters: a = 390.38(5) pm and c = 698.05(9) pm. It orders antiferromagnetically at T[sub N]=100[+-]2 K and exhibits a very strong anisotropy in the susceptibility vs temperature variation. The magnetic and thermodynamic properties of UOSe are successfully interpreted in the framework of a perturbative ab initio crystal field approach. (Author).

Molecular assembly and electro polymerization of 3,4-ethylenedioxy thiophene on Au(100) single crystal electrode using in-situ electrochemical scanning tunneling microscopy

International Nuclear Information System (INIS)

Garcia, Jonyl L.; Tongol, Bernard John V.; ShuehLin Yau

2012-01-01

Electrochemical scanning tunneling microscopy (Ec-STM) is a powerful technique that can provide molecular-level information regarding electrode surface processes in-situ in electrolyte solvent under ambient conditions. In this study, the adsorption and electro polymerization of an industrially important conducting polymer precursor, 3,4-ethylenedioxy thiophene (EDOT), on Au (100) single crystal was probed using Ec-STM. The Au (100) single crystal electrode substrate used for this study was fabricated using the well-known Clavilier's flame melting procedure. Cyclic voltammetry (CV) was used along with Ec-STM to characterize the bare, EDOT-modified, and poly(EDOT)-modified Au (100) single crystal electrode. Time-dependent Ec-STM imaging at 0.550 V showed the formation of an EDOT self-assembled monolayer through 2-D surface dillusion. The resulting EDOT molecular assembly on Au (100) single crystal electrode was found to fit in a 4√2χ3√2 unit cell. Difference in apparent corrugation between molecular rows was attributed to different angular orientation with respect to the substrate. The electro polymerization of EDOT on Au (100) single crystal electrode was done by potentiostatic and potentiodynamic methods. Both methods suggested a solution-process mechanism for EDOT electro polymerization. (author)

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

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

Monoclinic MB phase and phase instability in [110] field cooled Pb(Zn1/3Nb2/3)O3-4.5%PbTiO3 single crystals

Science.gov (United States)

Yao, Jianjun; Cao, Hu; Ge, Wenwei; Li, Jiefang; Viehland, D.

2009-08-01

We report the finding of a monoclinic MB phase in Pb(Zn1/3Nb2/3)O3-4.5%PbTiO3 single crystals. High precision x-ray diffraction investigations of [110] field cooled crystals have shown a transformation sequence of cubic(C)→tetragonal(T)→orthorhombic(O)→monoclinic(MB), which is different from that previously reported [A.-E. Renault et al., J. Appl. Phys. 97, 044105 (2005)]. Beginning in the zero-field-cooled condition at 383 K, a rhombohedral (R)→MB→O sequence was observed with increasing field. Coexisting MB and O phases were then found upon removal of field, which fully transformed to MB on cooling to room temperature.

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.

71Ga Chemical Shielding and Quadrupole Coupling Tensors of the Garnet Y(3)Ga(5)O(12) from Single-Crystal (71)Ga NMR

DEFF Research Database (Denmark)

Vosegaard, Thomas; Massiot, Dominique; Gautier, Nathalie

1997-01-01

A single-crystal (71)Ga NMR study of the garnet Y(3)Ga(5)O(12) (YGG) has resulted in the determination of the first chemical shielding tensors reported for the (71)Ga quadrupole. The single-crystal spectra are analyzed in terms of the combined effect of quadrupole coupling and chemical shielding ...

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.

Crystal Growth and Characterization of (Bi0.5Na0.5)TiO3-BaTiO3 Single Crystals Obtained by a Top-Seeded Solution Growth Method under High-Pressure Oxygen Atmosphere

Science.gov (United States)

Onozuka, Hiroaki; Kitanaka, Yuuki; Noguchi, Yuji; Miyayama, Masaru

2011-09-01

A single crystal of ferroelectric 0.88(Bi,Na)TiO3-0.12BaTiO3 (BNT-BT) solid solution with tetragonal P4mm structure was grown by a top-seeded solution growth (TSSG) method at a high oxygen pressure (PO2 ) of 0.9 MPa. The crystals exhibited a large remanent polarization (Pr) of 54 µC/cm2, which leads to a spontaneous polarization estimated to be 54 µC/cm2. The large Pr compared with that of crystals grown at PO2 = 0.1 MPa is suggested to originate from a low oxygen vacancy concentration. The high-PO2 TSSG method is demonstrated to be effective for obtaining large-sized, high-quality BNT-BT crystals.

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

On the growth of CH3NH3PbI3-xClx single crystal and characterization

Science.gov (United States)

Su, J.; Wang, W. F.; Lei, Y.; Zhang, L.; Xu, L. H.; Wang, D.; Lu, D.; Bai, Y.

2018-05-01

In this paper, CH3NH3PbI3-xClx crystal was grown by solution cooling method with CH3NH3I and PbCl2 as raw materials. Lead compounds and CH3NH3PbI3-xClx crystal with size about 6 mm × 4 mm × 2 mm were obtained. The chemical reactions with different CH3NH3I/PbCl2 ratios were analyzed. XPS shows the content of chlorine in CH3NH3PbI3-xClx is about 0.91%. PXRD, FT-IR, Raman and absorbance spectra were used to study the structure and optical properties of CH3NH3PbI3-xClx by comparing with CH3NH3PbI3 crystal. The CH3NH3PbI3-xClx crystal grown is of tetragonal structure with the lattice constants a = b = 8.8165 Å, c = 12.7920 Å and the bandgap value of 1.57 eV.

Magnetic and transport properties of Sm7Rh3 single crystal

International Nuclear Information System (INIS)

Tsutaoka, Takanori; Noguchi, Daisuke; Nakamori, Yuko; Nakamoto, Go; Kurisu, Makio

2013-01-01

A Sm 7 Rh 3 single crystal with Th 7 Fe 3 -type hexagonal structure was grown by the Czochralski method. The magnetic and transport measurements revealed a uniaxial magnetocrystalline anisotropy in the magnetic susceptibility, magnetization and electrical resistivity. Sm 7 Rh 3 was found to exhibit antiferromagnetic transition at T N =54.0 K and another magnetic transition at T t =25.0 K. The specific heat data clearly showed the bulk nature of paramagnetic to ordered magnetic phase transition by the presence of a sharp peak at T N and a small anomaly at T t . The paramagnetic susceptibility does not obey the Curie–Weiss law, attributing to the temperature independent Van Vleck contribution and Pauli paramagnetism of conduction electrons. Metamagnetic phase transitions were observed along the c-axis in the ordered states. The magnetic field H–temperature T phase diagram was constructed. Anisotropic paramagnetic electrical resistivity showed the small negative temperature coefficients

X-ray and neutron single-crystal diffraction on [Rbx(NH4)1-x]3H(SO4)2. I. Refinement of crystal structure of phase II with x=0.11 at 300 K

International Nuclear Information System (INIS)

Loose, A.; Wozniak, K.; Dominiak, P.; Smirnov, L.S.; Natkaniec, I.; Frontas'eva, M.V.; Pomyakushina, E.V.; Baranov, A.I.; Dolbinina, V.V

2006-01-01

The study of [Rb x (NH 4 ) 1-x ] 3 H(SO 4 ) 2 mixed crystals by X-ray single-crystal diffraction is known up to now only for x=0.57 at the temperatures 293 and 180 K. The crystal structures at these temperatures as was determined [1] belong to monoclinic phase II (C2/c sp. gr., Z=4). In accordance with this work, ammonium ions should be considered as deformed tetrahedra. Monoclinic phase II on the x-T phase diagram of [Rb x (NH 4 ) 1-x ] 3 H(SO 4 ) 2 mixed crystals, which has earlier been determined by the dielectric spectroscopy, is stabilized below room temperature if Rb concentration exceeds 9%. The presented results of X-ray and neutron single-crystal diffraction of the [Rb 0.11 (NH 4 ) 0.89 ] 3 H(SO 4 ) 2 mixed crystal at T= 300 K show that ammonium ions could be considered as regular tetrahedra

Angular and magnetic field dependences of critical current in irradiated YBaCuO single crystals

International Nuclear Information System (INIS)

Petrusenko, Yu.

2010-01-01

The investigation of mechanisms responsible for the current-carrying capability of irradiated high-temperature superconductors (HTSC) was realized. For the purpose, experiments were made to investigate the effect of point defects generated by high-energy electron irradiation on the critical temperature and the critical current in high-Tc superconducting single crystals YBa 2 Cu 3 O 7-x . The transport current density measured in HTSC single crystals YBa 2 Cu 3 O 7-x by the dc-method was found to exceed 80000 A/cm 2 . The experiments have demonstrated a more than 30-fold increase in the critical current density in single crystals irradiated with 2.5 MeV electrons to a dose of 3·10 18 el/cm 2 . Detailed studies were made into the anisotropy of critical current and the dependence of critical current on the external magnetic field strength in irradiated single crystals. A high efficiency of point defects as centers of magnetic vortex pinning in HTSC single crystals was first demonstrated.

Growth, and magnetic study of Sm0.4Er0.6FeO3 single crystal grown by optical floating zone technique

Science.gov (United States)

Wu, Anhua; Zhao, Xiangyang; Man, Peiwen; Su, Liangbi; Kalashnikova, A. M.; Pisarev, R. V.

2018-03-01

Sm0.4Er0.6FeO3 single crystals were successfully grown by optical floating zone method; high quality samples with various orientations were manufactured. Based on these samples, Magnetic property of Sm0.4Er0.6FeO3 single crystals were investigated systemically by means of the temperature dependence of magnetization. It indicated that compositional variations not only alter the spin reorientation temperature, but also the compensation temperature of the orthoferrites. Unlike single rare earth orthoferrites, the reversal transition temperature point of Sm0.4Er0.6FeO3 increases as magnetic field increases, which is positive for designing novel spin switching or magnetic sensor device.

Growth and surface topography of WSe_2 single crystal

International Nuclear Information System (INIS)

Dixit, Vijay; Vyas, Chirag; Pataniya, Pratik; Jani, Mihir; Pathak, Vishal; Patel, Abhishek; Pathak, V. M.; Patel, K. D.; Solanki, G. K.

2016-01-01

Tungsten Di-Selenide belongs to the family of TMDCs showing their potential applications in the fields of Optoelectronics and PEC solar cells. Here in the present investigation single crystals of WSe_2 were grown by Direct Vapour Transport Technique in a dual zone furnace having temperature difference of 50 K between the two zones. These single crystals were characterized by EDAX which confirms the stiochiometry of the grown crystals. Surface topography of the crystal was studied by optical micrograph showing the left handed spirals on the surface of WSe_2 crystals. Single crystalline nature of the crystals was confirmed by SAED.

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.

Time-Dependent Mechanical Response of APbX3 (A = Cs, CH3NH3; X = I, Br) Single Crystals

KAUST Repository

Reyes-Martinez, Marcos A.; Abdelhady, Ahmed L.; Saidaminov, Makhsud I.; Chung, Duck Young; Bakr, Osman; Kanatzidis, Mercouri G.; Soboyejo, Wole O.; Loo, Yueh-Lin

2017-01-01

The ease of processing hybrid organic-inorganic perovskite (HOIPs) films, belonging to a material class with composition ABX3 , from solution and at mild temperatures promises their use in deformable technologies, including flexible photovoltaic devices, sensors, and displays. To successfully apply these materials in deformable devices, knowledge of their mechanical response to dynamic strain is necessary. The authors elucidate the time- and rate-dependent mechanical properties of HOIPs and an inorganic perovskite (IP) single crystal by measuring nanoindentation creep and stress relaxation. The observation of pop-in events and slip bands on the surface of the indented crystals demonstrate dislocation-mediated plastic deformation. The magnitudes of creep and relaxation of both HOIPs and IPs are similar, negating prior hypothesis that the presence of organic A-site cations alters the mechanical response of these materials. Moreover, these samples exhibit a pronounced increase in creep, and stress relaxation as a function of indentation rate whose magnitudes reflect differences in the rates of nucleation and propagation of dislocations within the crystal structures of HOIPs and IP. This contribution provides understanding that is critical for designing perovskite devices capable of withstanding mechanical deformations.

Time-Dependent Mechanical Response of APbX3 (A = Cs, CH3NH3; X = I, Br) Single Crystals

KAUST Repository

Reyes-Martinez, Marcos A.

2017-05-02

The ease of processing hybrid organic-inorganic perovskite (HOIPs) films, belonging to a material class with composition ABX3 , from solution and at mild temperatures promises their use in deformable technologies, including flexible photovoltaic devices, sensors, and displays. To successfully apply these materials in deformable devices, knowledge of their mechanical response to dynamic strain is necessary. The authors elucidate the time- and rate-dependent mechanical properties of HOIPs and an inorganic perovskite (IP) single crystal by measuring nanoindentation creep and stress relaxation. The observation of pop-in events and slip bands on the surface of the indented crystals demonstrate dislocation-mediated plastic deformation. The magnitudes of creep and relaxation of both HOIPs and IPs are similar, negating prior hypothesis that the presence of organic A-site cations alters the mechanical response of these materials. Moreover, these samples exhibit a pronounced increase in creep, and stress relaxation as a function of indentation rate whose magnitudes reflect differences in the rates of nucleation and propagation of dislocations within the crystal structures of HOIPs and IP. This contribution provides understanding that is critical for designing perovskite devices capable of withstanding mechanical deformations.

Three-dimensional oriented attachment growth of single-crystal pre-perovskite PbTiO3 hollowed fibers

KAUST Repository

Zhao, Ruoyu

2017-12-11

Hollowed single-crystal pre-perovskite PbTiO fibers (PP-PTF) were successfully synthesized via a polyvinyl alcohol (PVA) assisted hydrothermal process. The as-prepared PP-PTF were characterized to be 0.3-1 μm in diameter and tens of micrometers in length by adjusting the concentration of PVA to 0.8 g L. Microstructure characterization of the samples at different reaction times revealed that PP-PTF were formed via a three-dimensional (3D) hierarchical oriented attachment (OA) growth process. The initial growth units were determined to be single-crystal pre-perovskite PbTiO fibers with a diameter of 10-20 nm. Zeta potential measurement suggested that the main driving force of the OA process is the surface electrostatic force, which is induced by the incompletely bonded Pb and O atomic layers on the surface of the {110} plane. Moreover, molecular dynamics simulations have been employed to reveal a stable configuration of the initial pre-perovskite PbTiO growth units, agreeing well with the experimental results.

ESR studies of electron irradiated K3Ir(CN)6 in KCl single crystals

International Nuclear Information System (INIS)

Vugman, N.V.; Pinhal, N.M.

1983-01-01

ESR studies of KCl single crystals doped with small amounts of K 3 Ir(CN) 6 and submitted to a prolongued 2 MeV electron irradiation at room temperature reveal the presence of the [IR(CN) 5 Cl] 4- and [Ir(CN) 4 Cl 2 ] 4- new molecular species. Ligand spin densities and ligand field parameters are calculated from the experimental hyperfine and superhyperfine interactions and compared to previous data on the [Ir(CN) 5 ] 4- species. (Author) [pt

Balanced Photodetection in One-Step Liquid-Phase-Synthesized CsPbBr3 Micro-/Nanoflake Single Crystals.

Science.gov (United States)

Zheng, Wei; Xiong, Xufan; Lin, Richeng; Zhang, Zhaojun; Xu, Cunhua; Huang, Feng

2018-01-17

Here, we reported a low-cost and high-compatibility one-step liquid-phase synthesis method for synthesizing high-purity CsPbBr 3 micro-/nanoflake single crystals. On the basis of the high-purity CsPbBr 3 , we further prepared a low-dimensional photodetector capable of balanced photodetection, involving both high external quantum efficiency and rapid temporal response, which is barely realized in previously reported low-dimensional photodetectors.

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.

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.

Single Crystals Grown Under Unconstrained Conditions

Science.gov (United States)

Sunagawa, Ichiro

Based on detailed investigations on morphology (evolution and variation in external forms), surface microtopography of crystal faces (spirals and etch figures), internal morphology (growth sectors, growth banding and associated impurity partitioning) and perfection (dislocations and other lattice defects) in single crystals, we can deduce how and by what mechanism the crystal grew and experienced fluctuation in growth parameters through its growth and post-growth history under unconstrained condition. The information is useful not only in finding appropriate way to growing highly perfect and homogeneous single crystals, but also in deciphering letters sent from the depth of the Earth and the Space. It is also useful in discriminating synthetic from natural gemstones. In this chapter, available methods to obtain molecular information are briefly summarized, and actual examples to demonstrate the importance of this type of investigations are selected from both natural minerals (diamond, quartz, hematite, corundum, beryl, phlogopite) and synthetic crystals (SiC, diamond, corundum, beryl).

Fundamental piezo-Hall coefficients of single crystal p-type 3C-SiC for arbitrary crystallographic orientation

Science.gov (United States)

Qamar, Afzaal; Dao, Dzung Viet; Phan, Hoang-Phuong; Dinh, Toan; Dimitrijev, Sima

2016-08-01

Piezo-Hall effect in a single crystal p-type 3C-SiC, grown by LPCVD process, has been characterized for various crystallographic orientations. The quantified values of the piezo-Hall effect in heavily doped p-type 3C-SiC(100) and 3C-SiC(111) for different crystallographic orientations were used to obtain the fundamental piezo-Hall coefficients, P 12 = ( 5.3 ± 0.4 ) × 10 - 11 Pa - 1 , P 11 = ( - 2.6 ± 0.6 ) × 10 - 11 Pa - 1 , and P 44 = ( 11.42 ± 0.6 ) × 10 - 11 Pa - 1 . Unlike the piezoresistive effect, the piezo-Hall effect for (100) and (111) planes is found to be independent of the angle of rotation of the device within the crystal plane. The values of fundamental piezo-Hall coefficients obtained in this study can be used to predict the piezo-Hall coefficients in any crystal orientation which is very important for designing of 3C-SiC Hall sensors to minimize the piezo-Hall effect for stable magnetic field sensitivity.

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.

Flux flow and pinning by twin boundaries in single crystal YBa2Cu3O7-δ

International Nuclear Information System (INIS)

Kwok, W.K.; Fleshler, S.; Welp, U.; Vinokur, V.M.; Downey, J.; Crabtree, G.W.

1993-01-01

We present AC magnetoresistance measurements in fully oxygenated and oxygen deficient single crystals of YBa 2 Cu 3 O 7-δ . From the resistive broadening in magnetic field for H parallel ab parallel I and H parallel ab perpendicular to I, we demonstrate the existence of Lorentz force induced flux flow dissipation near T c . Using a novel crossed magnetic field technique where high angular resolution of Δθ 2 Cu 3 O 7-δ single crystals. The twin boundary pinning onset is characterized by a critical angle model and we extract a phase diagram for the onset of twin boundary pinning. We report on a strong magnetic field dependence of the critical angle for twin boundary pinning for H parallel c which is absent for H parallel ab. In addition, we find the critical angle θ * for H parallel c is greater than that observed for H parallel ab for nearly stoichiometric samples. (orig.)

Spatiotemporal dynamics of the spin transition in [Fe (HB(tz)3) 2] single crystals

Science.gov (United States)

Ridier, Karl; Rat, Sylvain; Shepherd, Helena J.; Salmon, Lionel; Nicolazzi, William; Molnár, Gábor; Bousseksou, Azzedine

2017-10-01

The spatiotemporal dynamics of the spin transition have been thoroughly investigated in single crystals of the mononuclear spin-crossover (SCO) complex [Fe (HB (tz )3)2] (tz = 1 ,2 ,4-triazol-1-yl) by optical microscopy. This compound exhibits an abrupt spin transition centered at 334 K with a narrow thermal hysteresis loop of ˜1 K (first-order transition). Most single crystals of this compound reveal exceptional resilience upon repeated switching (several hundred cycles), which allowed repeatable and quantitative measurements of the spatiotemporal dynamics of the nucleation and growth processes to be carried out. These experiments revealed remarkable properties of the thermally induced spin transition: high stability of the thermal hysteresis loop, unprecedented large velocities of the macroscopic low-spin/high-spin phase boundaries up to 500 µm/s, and no visible dependency on the temperature scan rate. We have also studied the dynamics of the low-spin → high-spin transition induced by a local photothermal excitation generated by a spatially localized (Ø = 2 μ m ) continuous laser beam. Interesting phenomena have been evidenced both in quasistatic and dynamic conditions (e.g., threshold effects and long incubation periods, thermal activation of the phase boundary propagation, stabilization of the crystal in a stationary biphasic state, and thermal cutoff frequency). These measurements demonstrated the importance of thermal effects in the transition dynamics, and they enabled an accurate determination of the thermal properties of the SCO compound in the framework of a simple theoretical model.

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)

Czochralski growth and characterization of {beta}-Ga{sub 2}O{sub 3} single crystals

Energy Technology Data Exchange (ETDEWEB)

Galazka, Z.; Uecker, R.; Irmscher, K.; Albrecht, M.; Klimm, D.; Pietsch, M.; Bruetzam, M.; Bertram, R.; Ganschow, S.; Fornari, R. [Leibniz Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin (Germany)

2010-12-15

Transparent semiconducting {beta}-Ga{sub 2}O{sub 3} single crystals were grown by the Czochralski method from an iridium crucible under a dynamic protective atmosphere to control partial pressures of volatile species of Ga{sub 2}O{sub 3}. Thermodynamic calculations on different atmospheres containing CO{sub 2}, Ar and O{sub 2} reveal that CO{sub 2} growth atmosphere combined with overpressure significantly decreases evaporation of volatile Ga{sub 2}O{sub 3} species without any harm to iridium crucible. It has been found that CO{sub 2}, besides providing high oxygen concentration at high temperatures, is also acting as a minor reducing agent for Ga{sub 2}O{sub 3}. Different coloration of obtained crystals as well as optical and electrical properties are directly correlated with growth conditions (atmosphere, pressure and temperature gradients), but not with residual impurities. Typical electrical properties of the n-type {beta}-Ga{sub 2}O{sub 3} crystals at room temperature are: {rho} = 0.1 - 0.3 {omega}cm, {mu}{sub n,Hall} = 110 - 150 cm{sup 2}V{sup -1}s{sup -1}, n{sub Hall} = 2 - 6 x 10{sup 17} cm{sup -3} and E{sub Ionisation} = 30 - 40 meV. A decrease of transmission in the IR-region is directly correlated with the free carrier concentration and can be effectively modulated by the dynamic growth atmosphere. Electron paramagnetic resonance (EPR) spectra exhibit an isotropic shallow donor level and anisotropic defect level. According to differential thermal analysis (DTA) measurements, there is substantially no mass change of {beta}-Ga{sub 2}O{sub 3} crystals below 1200 C (i.e. no decomposition) under oxidizing or neutral atmosphere, while the mass gradually decreases with temperature above 1200 C. High resolution transmission electron microscopy (HRTEM) images at atomic resolution show the presence of vacancies, which can be attributed to Ga or O sites, and interstitials, which can likely be attributed to Ga atoms. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGa

Production and several properties of single crystal austenitic stainless steels

International Nuclear Information System (INIS)

Okamoto, Kazutaka; Yoshinari, Akira; Kaneda, Junya; Aono, Yasuhisa; Kato, Takahiko

1998-01-01

The single crystal austenitic stainless steels Type 316L and 304L were grown in order to improve the resistance to stress corrosion cracking (SCC) using a unidirectional solidification method which can provide the large size single crystals. The mechanical properties and the chemical properties were examined. The orientation and temperature dependence of tensile properties of the single crystals were measured. The yield stress of the single crystal steels are lower than those of the conventional polycrystal steels because of the grain boundary strength cannot be expected in the single crystal steels. The tensile properties of the single crystal austenitic stainless steel Type 316L depend strongly on the orientation. The tensile strength in orientation are about 200 MPa higher than those in the and orientations. The microstructure of the single crystal consists of a mixture of the continuous γ-austenitic single crystal matrix and the δ-ferrite phase so that the effects of the γ/δ boundaries on the chemical properties were studied. The effects of the δ-ferrite phases and the γ/δ boundaries on the resistance to SCC were examined by the creviced bent beam test (CBB test). No crack is observed in all the CBB test specimens of the single crystals, even at the γ/δ boundaries. The behavior of the radiation induced segregation (RIS) at the γ/δ boundaries in the single crystal austenitic stainless steel Type 316L was evaluated by the electron irradiation test in the high voltage electron microscope (HVEM). The depletion of oversized solute chromium at the γ/δ boundary in the single crystal austenitic stainless steel Type 316L is remarkably lower than that at the grain boundary in the polycrystalline-type 316L. (author)

Anisotropic charge transport in large single crystals of π-conjugated organic molecules.

Science.gov (United States)

Hourani, Wael; Rahimi, Khosrow; Botiz, Ioan; Koch, Felix Peter Vinzenz; Reiter, Günter; Lienerth, Peter; Heiser, Thomas; Bubendorff, Jean-Luc; Simon, Laurent

2014-05-07

The electronic properties of organic semiconductors depend strongly on the nature of the molecules, their conjugation and conformation, their mutual distance and the orientation between adjacent molecules. Variations of intramolecular distances and conformation disturb the conjugation and perturb the delocalization of charges. As a result, the mobility considerably decreases compared to that of a covalently well-organized crystal. Here, we present electrical characterization of large single crystals made of the regioregular octamer of 3-hexyl-thiophene (3HT)8 using a conductive-atomic force microscope (C-AFM) in air. We find a large anisotropy in the conduction with charge mobility values depending on the crystallographic orientation of the single crystal. The smaller conduction is in the direction of π-π stacking (along the long axis of the single crystal) with a mobility value in the order of 10(-3) cm(2) V(-1) s(-1), and the larger one is along the molecular axis (in the direction normal to the single crystal surface) with a mobility value in the order of 0.5 cm(2) V(-1) s(-1). The measured current-voltage (I-V) curves showed that along the molecular axis, the current followed an exponential dependence corresponding to an injection mode. In the π-π stacking direction, the current exhibits a space charge limited current (SCLC) behavior, which allows us to estimate the charge carrier mobility.

Formation of oriented nitrides by N+ ion implantation in iron single crystals

International Nuclear Information System (INIS)

Costa, A.R.G.; Silva, R.C. da; Ferreira, L.P.; Carvalho, M.D.; Silva, C.; Franco, N.; Godinho, M.

2014-01-01

Iron single crystals were implanted with nitrogen at room temperature, with a fluence of 5×10 17 cm −2 and 50 keV energy, to produce iron nitride phases and characterize the influence of the crystal orientation. The stability and evolution of the nitride phases and diffusion of implanted nitrogen were studied as a function of successive annealing treatments at 250 °C in vacuum. The composition, structure and magnetic properties were characterized using RBS/channeling, X-Ray Diffraction, Magnetic Force Microscopy, Magneto-optical Kerr Effect and Conversion Electron Mössbauer Spectroscopy. In the as-implanted state the formation of Fe 2 N phase was clearly identified in all single crystals. This phase is not stable at 250 °C and annealing at this temperature promotes the formation of ε-Fe 3 N, or γ′-Fe 4 N, depending on the orientation of the substrate. - Highlights: • Oriented magnetic iron nitrides were obtained by nitrogen implantation into iron single crystals. • The stable magnetic nitride phase at 250 °C depends on the orientation of the host single crystal, being γ'-Fe 4 N or ε-Fe 3 N. • The easy magnetization axis was found to lay in the (100) plane for cubic γ'-Fe 4 N and out of (100) plane for hexagonal ε-Fe 3 N

The role of crystal orientation and surface proximity in the self-similar behavior of deformed Cu single crystals

Energy Technology Data Exchange (ETDEWEB)

Pang, Judy W.L., E-mail: pangj@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, 1 Behtel Valley Road, Oak Ridge, TN 37831 (United States); Ice, Gene E. [Materials Science and Technology Division, Oak Ridge National Laboratory, 1 Behtel Valley Road, Oak Ridge, TN 37831 (United States); Liu Wenjun [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States)

2010-11-25

We report on novel 3D spatially resolved X-ray diffraction microscopy studies of self-affine behavior in deformed single crystals. This study extends surface profile measurements of self-affined morphology changes in single crystals during deformation to include local lattice rotations and sub-surface behavior. Investigations were made on the spatial correlation of the local lattice rotations in 8% tensile deformed Cu single crystals oriented with [1 2 3], [1 1 1] and [0 0 1] axes parallel to the tensile axis. The nondestructive depth-resolved measurements were made over a length scale of one to hundreds of micrometers. Self-affined correlation was found both at the surface and below the surface of the samples. A universal exponent for the power-law similar to that observed with surface profile methods is found at the surface of all samples but crystallographically sensitive changes are observed as a function of depth. Correlation lengths of the self-affine behavior vary with the [1 2 3] crystal exhibiting the longest self-affine length scale of 70 {mu}m with only 18 {mu}m for the [1 1 1] and [0 0 1] crystals. These measurements illuminate the transition from surface-like to bulk-like deformation behavior and provide new quantitative information to guide emerging models of self-organized structures in plasticity.

Observations related to hydrogen in powder and single crystal samples of YB2Cu3O7-δ

International Nuclear Information System (INIS)

Porath, D.; Grayevsky, A.; Kaplan, N.; Shaltiel, D.; Yaron, U.; Walker, E.

1994-01-01

New observations related to hydrogenation of YBa 2 Cu 3 O 7-δ (YBCO) are reported: (a) The effects of sample preparation on the H concentration in ''uncharged'' YBCO samples is investigated, and it is shown through nuclear magnetic resonance measurements that samples of YBCO prepared by ''standard'' solid-state reaction procedures may contain ab initio up to 0.2 atoms formula -1 of hydrogen. (b) It is demonstrated that one may introduce up to 0.3 atoms formula -1 into single crystal samples of YBCO without destroying the macroscopic crystal. The significance of the above observations is discussed briefly. (orig.)

Magnetic, electric and electron magnetic resonance properties of orthorhombic self-doped La1-xMnO3 single crystals

International Nuclear Information System (INIS)

Markovich, V; Fita, I; Shames, A I; Puzniak, R; Rozenberg, E; Yuzhelevski, Ya; Mogilyansky, D; Wisniewski, A; Mukovskii, Ya M; Gorodetsky, G

2003-01-01

The effect of lanthanum deficiency on structural, magnetic, transport, and electron magnetic resonance (EMR) properties has been studied in a series of La 1-x MnO 3 (x = 0.01, 0.05, 0.11, 0.13) single crystals. The x-ray diffraction study results for the crystals were found to be compatible with a single phase of orthorhombic symmetry. The magnetization curves exhibit weak ferromagnetism for all samples below 138 K. It was found that both the spontaneous magnetization and the coercive field increase linearly with x. The pressure coefficient dT N /dP decreases linearly with self-doping, from a value of 0.68 K kbar -1 for La 0.99 MnO 3 to 0.33 K kbar -1 for La 0.87 MnO 3 . The resistivity of low-doped La 0.99 MnO 3 crystal is of semiconducting character, while that of La 0.87 MnO 3 depends weakly on temperature between 180 and 210 K. It was found that the magnetic and transport properties of the self-doped compounds may be attributed to a phase separation involving an antiferromagnetic matrix and ferromagnetic clusters. The latter phases as well as their paramagnetic precursors have been directly observed by means of EMR

Solid-state syntheses and single-crystal characterizations of three tetravalent thorium and uranium silicates

International Nuclear Information System (INIS)

Jin, Geng Bang; Soderholm, L.

2015-01-01

Colorless crystals of ThSiO 4 (huttonite) (1) and (Ca 0.5 Na 0.5 ) 2 NaThSi 8 O 20 (2) have been synthesized by the solid-state reactions of ThO 2 , CaSiO 3 , and Na 2 WO 4 at 1073 K. Green crystals of (Ca 0.5 Na 0.5 ) 2 NaUSi 8 O 20 (3) have been synthesized by the solid-state reactions of UO 2 , CaSiO 3 , and Na 2 WO 4 at 1003 K. All three compounds have been characterized by single-crystal X-ray diffraction. Compound 1 adopts a monazite-type three-dimensional condensed structure, which is built from edge- and corner-shared ThO 9 polyhedra and SiO 4 tetrahedra. Compounds 2 and 3 are isostructural and they crystallize in a steacyite-type structure. The structure consists of discrete pseudocubic [Si 8 O 20 ] 8− polyanions, which are connected by An 4+ cations into a three-dimensional framework. Each An atom coordinates to eight monodentate [Si 8 O 20 ] 8− moieties in a square antiprismatic geometry. Na + and Ca 2+ ions reside in the void within the framework. Raman spectra of 1, 2, and 3 were collected on single crystal samples. 1 displays more complex vibrational bands than thorite. Raman spectra of 2 and 3 are analogous with most of vibrational bands located at almost the same regions. - Graphical abstract: A Raman spectrum and crystal structures of (Ca 0.5 Na 0.5 ) 2 NaAnSi 8 O 20 (An=Th, U), which contain pseudocubic [Si 8 O 20 ] 8− polyanions and eight-coordinate An 4+ cations. - Highlights: • Single crystal growth of three tetravalent actinide silicates from melts. • Single-crystal structures and Raman spectra of (Ca 0.5 Na 0.5 ) 2 NaAnSi 8 O 20 (An=Th, U). • First report of Raman spectrum of huttonite on single crystal samples

Strong Nonvolatile Magnon-Driven Magnetoelectric Coupling in Single-Crystal Co /[PbMg1/3Nb2/3O3] 0.71[PbTiO3]0.29 Heterostructures

Science.gov (United States)

Zhou, Cai; Shen, Lvkang; Liu, Ming; Gao, Cunxu; Jia, Chenglong; Jiang, Changjun

2018-01-01

The ability to manipulate the magnetism on interfacing ferromagnetic and ferroelectric materials via electric fields to achieve an emergent multiferroic response has enormous potential for nanoscale devices with novel functionalities. Herein, a strong electric-field control of the magnetism modulation is reported for a single-crystal Co (14 nm )/(001 )Pb (Mg1/3Nb2/3) 0.7Ti0.3O3 (PMN-PT) heterostructure by fabricating an epitaxial Co layer on a PMN-PT substrate. Electric-field-tuned ferromagnetic resonance exhibits a large resonance field shift, with a 120-Oe difference between that under positive and negative remanent polarizations, which demonstrates nonvolatile electric-field control of the magnetism. Further, considering the complexity of the twofold symmetry magnetic anisotropy, the linear change of the fourfold symmetry magnetic anisotropy, relating to the single-crystal cubic magnetocrystal anisotropy of the Co thin film, is resolved and quantified to exert a magnon-driven, strong direct magnetoelectric effect on the Co /PMN -PT interface. These results are promising for future multiferroic devices.

Synthesis of formamidinium lead iodide perovskite bulk single crystal and its optical properties

Science.gov (United States)

Zheng, Hongge; Duan, Junjie; Dai, Jun

2017-07-01

Formamidinium lead iodide (FAPbI3) is a promising hybrid perovskite material for optoelectronic devices. We synthesized bulk single crystal FAPbI3 by a rapid solution crystallization method. X-ray diffraction (XRD) was performed to characterize the crystal structure. Temperature-dependent photoluminescence (PL) spectra of the bulk single crystal FAPbI3 were measured from 10 to 300 K to explain PL recombination mechanism. It shows that near band edge emission blueshifts with the temperature increasing from 10 to 120 K and from 140 K to room temperature, a sudden emission band redshift demonstrates near 140 K because of the phase transition from orthorhombic phase to cubic phase. From the temperature-dependent PL spectra, the temperature coefficients of the bandgap and thermal activation energies of FAPbI3 perovskite are fitted.

Correlation of the superconducting transition to oxygen stoichiometry in single-crystal Ba1-xKxBiO3-y

Science.gov (United States)

Mosley, W. D.; Dykes, J. W.; Klavins, P.; Shelton, R. N.; Sterne, P. A.; Howell, R. H.

1993-07-01

Temperature-dependent positron-lifetime experiments have been performed from room temperature to 15 K on single crystals of the oxide superconductor Ba1-xKxBiO3-y. Results indicate that the filling of oxygen vacancies has a marked impact on the superconducting properties of this system. Cation defect concentrations were below the detectable limit of positron-annihilation-analysis techniques in this material, which is in sharp contrast to identical studies on polycrystalline samples. We find that the positron lifetime in these electrochemically deposited single crystals is determined by the oxygen stoichiometry of the lattice, but there is no experimental signature of strong positron localization. By performing a subsequent oxygen anneal on the crystals, the superconducting transition is sharpened and the onset is raised. The observed change in positron lifetime associated with this annealing procedure is in quantitative agreement with theory.

Organic field-effect transistors using single crystals

International Nuclear Information System (INIS)

Hasegawa, Tatsuo; Takeya, Jun

2009-01-01

Organic field-effect transistors using small-molecule organic single crystals are developed to investigate fundamental aspects of organic thin-film transistors that have been widely studied for possible future markets for 'plastic electronics'. In reviewing the physics and chemistry of single-crystal organic field-effect transistors (SC-OFETs), the nature of intrinsic charge dynamics is elucidated for the carriers induced at the single crystal surfaces of molecular semiconductors. Materials for SC-OFETs are first reviewed with descriptions of the fabrication methods and the field-effect characteristics. In particular, a benchmark carrier mobility of 20-40 cm 2 Vs -1 , achieved with thin platelets of rubrene single crystals, demonstrates the significance of the SC-OFETs and clarifies material limitations for organic devices. In the latter part of this review, we discuss the physics of microscopic charge transport by using SC-OFETs at metal/semiconductor contacts and along semiconductor/insulator interfaces. Most importantly, Hall effect and electron spin resonance (ESR) measurements reveal that interface charge transport in molecular semiconductors is properly described in terms of band transport and localization by charge traps. (topical review)

Prospects for the synthesis of large single-crystal diamonds

International Nuclear Information System (INIS)

Khmelnitskiy, R A

2015-01-01

The unique properties of diamond have stimulated the study of and search for its applications in many fields, including optics, optoelectronics, electronics, biology, and electrochemistry. Whereas chemical vapor deposition allows the growth of polycrystalline diamond plates more than 200 mm in diameter, most current diamond application technologies require large-size (25 mm and more) single-crystal diamond substrates or films suitable for the photolithography process. This is quite a challenge, because the largest diamond crystals currently available are 10 mm or less in size. This review examines three promising approaches to fabricating large-size diamond single crystals: growing large-size single crystals, the deposition of heteroepitaxial diamond films on single-crystal substrates, and the preparation of composite diamond substrates. (reviews of topical problems)

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.

EPR and optical absorption studies of VO2+ doped L-alanine (C3H7NO2) single crystals

International Nuclear Information System (INIS)

Biyik, Recep

2009-01-01

VO 2+ doped L-alanine (C 3 H 7 NO 2 ) single crystals and powders are examined by electron paramagnetic resonance (EPR) and optical absorption spectroscopy. Three magnetically different sites are resolved from angular variations of L-alanine single crystal EPR spectra. In some specific orientations each VO 2+ line splits into three superhyperfine lines with intensities of 1:2:1 and maximum splitting value of 2.23 mT. The local symmetries of VO 2+ complex sites are nearly axial. The optical absorption spectra show three bands. Spin Hamiltonian parameters are measured and molecular orbital coefficients are calculated by correlating EPR and optical absorption data for the central vanadyl ion.

Near-Band-Edge Optical Responses of CH3NH3PbCl3 Single Crystals: Photon Recycling of Excitonic Luminescence

Science.gov (United States)

Yamada, Takumi; Aharen, Tomoko; Kanemitsu, Yoshihiko

2018-02-01

The determination of the band gap and exciton energies of lead halide perovskites is very important from the viewpoint of fundamental physics and photonic device applications. By using photoluminescence excitation (PLE) spectra, we reveal the optical properties of CH3NH3PbCl3 single crystals in the near-band-edge energy regime. The one-photon PLE spectrum exhibits the 1 s exciton peak at 3.11 eV. On the contrary, the two-photon PLE spectrum exhibits no peak structure. This indicates photon recycling of excitonic luminescence. By analyzing the spatial distribution of the excitons and photon recycling, we obtain 3.15 eV for the band gap energy and 41 meV for the exciton binding energy.

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.

Magnetic phase transitions and large mass enhancement in single crystal CaFe4As3

International Nuclear Information System (INIS)

Zhang Xiao-Dong; Wu Wei; Zheng Ping; Wang Nan-Lin; Luo Jian-Lin

2012-01-01

High quality single crystal CaFe 4 As 3 was grown by using the Sn flux method. Unlike layered CaFe 2 As 2 , CaFe 4 As 3 crystallizes in an orthorhombic three-dimensional structure. Two magnetic ordering transitions are observed at ∼ 90 K and ∼ 27 K, respectively. The high temperature transition is an antiferromagnetic(AF) ordering transition. However, the low temperature transition shows complex properties. It shows a ferromagnetic-like transition when a field is applied along b-axis, while antiferromagnetism-like transition when a field is applied perpendicular to b-axis. These results suggest that the low temperature transition at 27 K is a first-order transition from an AF state to a canted AF state. In addition, the low temperature electron specific heat coefficient reaches as high as 143 mJ/mol·K 2 , showing a heavy fermion behavior. (rapid communication)

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

Science.gov (United States)

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

2011-11-01

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

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.

Pyroelectric properties of phosphoric acid-doped TGS single crystals

International Nuclear Information System (INIS)

Saxena, Aparna; Fahim, M; Gupta, Vinay; Sreenivas, K

2003-01-01

Pyroelectric properties of phosphoric acid (H 3 PO 4 )-doped triglycine sulfate (TGSP) single crystals grown from solutions containing 0.1-0.5 mol of H 3 PO 4 have been studied. Incorporation of H 3 PO 4 into the crystal lattice is found to induce an internal bias field (E b ) and is observed through the presence of a sustained polarization and pyroelectricity beyond the transition temperature. The internal bias field has been estimated theoretically by fitting the experimentally measured data on temperature dependence of the pyroelectric coefficient (λ), dielectric constant (ε') and polarization (P). A high E b value in the range 9 x 10 3 -15.5 x 10 4 V m -1 is obtained for crystals grown with 0.1-0.5 mol of H 3 PO 4 in the solution, and a specific concentration of 0.2-0.25 mol of H 3 PO 4 in the solution during crystal growth is found to be optimum for a high figure of merit for detectivity, F d = 428 μC m -2 K -1

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.

Deuterium resonance of KD3(SeO3)2 single crystals above and below phase transition

International Nuclear Information System (INIS)

Grande, S.; Mecke, H.D.; Shuvalov, L.A.

1978-01-01

Deuterium resonance investigations of KD 3 (SeO 3 ) 2 single crystals are performed both in the paraelectric and ferroelastic phase. The electric quadrupole coupling constants lie between 120 and 180 kHz. The directions of the qsub(zz)-components of the EFG-tensors are in good agreement with the hydrogen bond directions determined by X-ray structure analysis and neutron scattering. There are two types of hydrogen bonds with different behaviour at phase transition. The O(2)...H...O(2) bond shows an order-disorder process in contrast to the O(3)-H...O(1) bond being present below Tsub(c) in two bond lengths. The first bond turns out of the ac-plane by the monoclinic angle. The temperature dependence of the spectra is examined at a defined orientation between room temperature and -40 0 C. (author)

Advances in the Growth and Characterization of Relaxor-PT-Based Ferroelectric Single Crystals

Directory of Open Access Journals (Sweden)

Jun Luo

2014-07-01

Full Text Available Compared to Pb(Zr1−xTixO3 (PZT polycrystalline ceramics, relaxor-PT single crystals offer significantly improved performance with extremely high electromechanical coupling and piezoelectric coefficients, making them promising materials for piezoelectric transducers, sensors and actuators. The recent advances in crystal growth and characterization of relaxor-PT-based ferroelectric single crystals are reviewed in this paper with emphases on the following topics: (1 the large crystal growth of binary and ternary relaxor-PT-based ferroelectric crystals for commercialization; (2 the composition segregation in the crystals grown from such a solid-solution system and possible solutions to reduce it; (3 the crystal growth from new binary and ternary compositions to expand the operating temperature and electric field; (4 the crystallographic orientation dependence and anisotropic behaviors of relaxor-PT-based ferroelectriccrystals; and (5 the characterization of the dielectric, elastic and piezoelectric properties of the relaxor-PT-based ferroelectriccrystals under small and large electric fields.

Anisotropy in Ba2Cu3O4Cl2 single crystals grown by the traveling solvent floating zone method

International Nuclear Information System (INIS)

Yamada, Shigeki; Iwagaki, Yohei; Noro, Sumiko

2007-01-01

Magnetic and electrical properties of layered copper oxychloride Ba 2 Cu 3 O 4 Cl 2 single crystals are measured. Single crystal growth of Ba 2 Cu 3 O 4 Cl 2 by the traveling solvent floating zone method is attempted using Ba 3 Cu 2 O 4 Cl 2 as solvent. By optimization of the growth conditions, large single crystals of (φ5mmx30mm) of Ba 2 Cu 3 O 4 Cl 2 are grown. The resistivity with the current parallel to the c-axis is 10 2 -10 3 times larger than that with the current perpendicular to the a-axis. The temperature dependence of the dielectric spectrum for each direction is measured and analyzed by using the Debye model. The spectrum width, which is related to the effective number of electrons (n/m), does not show an appreciable dependence on temperature. The characteristic frequencies at which the dielectric constant changes, which are related to the dissipation (γ), increase with warming. The temperature dependence is almost the same as the resistivity curve. This indicates that the hopping process dominates both DC- and AC-type electrical transport. The spectrum width with the electric field parallel to the a-axis is 30 times larger than that with the electric field parallel to the c-axis. On the other hand, the characteristic frequencies do not show an appreciable dependence on electric field direction

How far could energy transport within a single crystal

Science.gov (United States)

Zhang, Yifan; Che, Yanke; Zhao, Jincai; Steve, Granick

Efficient transport of excitation energy over long distance is a vital process in light-harvesting systems and molecular electronics. The energy transfer distance is largely restricted by the probability decay of the exciton when hopping within a single crystal. Here, we fabricated an organic single crystal within which the energy could transfer more than 100 μm, a distance only limited by its crystal size. Our system could be regarded as a ``Sprint relay game'' performing on different surface of tracks. Photoinduced ``athletes'' (excitons) triggered intermolecular ``domino'' reaction to propagate energy for a long distance. In addition, athletes with the same ability runs much farther on smooth ideal track (single crystal assembled from merely van der Waals interaction) than bumpy mud track (crystal assembled from combination of pi-stacking, hydrogen bond and van der Waals interactions). Our finding presents new physics on enhancing energy transfer length within a single crystal. Current Affiliation: Institute for Basic Science, South Korea.

Doping of Czochralski-grown bulk β-Ga2O3 single crystals with Cr, Ce and Al

Science.gov (United States)

Galazka, Zbigniew; Ganschow, Steffen; Fiedler, Andreas; Bertram, Rainer; Klimm, Detlef; Irmscher, Klaus; Schewski, Robert; Pietsch, Mike; Albrecht, Martin; Bickermann, Matthias

2018-03-01

We experimentally evaluated segregation of Cr, Ce and Al in bulk β-Ga2O3 single crystals grown by the Czochralski method, as well as the impact of these dopants on optical properties. The segregation of Cr and Ce and their incorporation into the β-Ga2O3 crystal structure strongly depends on O2 concentration in the growth atmosphere which has a noticeable impact on decomposition of Ga2O3 and Cr2O3, as well as on the charge state of Cr and Ce. Effective segregation coefficients for Cr are in the range of 3.1-1.5 at 7-24 vol% O2, while for Ce they are roughly below 0.01 at 1.5-34 vol% O2. The effective segregation coefficient for Al is 1.1 at 1.5-21 vol% O2. Both dopants Ce and Al have a thermodynamically stabilizing effect on β-Ga2O3 crystal growth by supressing decomposition. While Ce has no impact on the optical transmittance in the ultraviolet and visible regions, in Cr doped crystals we observe three absorption bands due to Cr3+ on octahedral Ga sites, one in the ultraviolet merging with the band edge absorption of β-Ga2O3 and two in the visible spectrum, for which we estimate the absorption cross sections. Al doping also does not induce dopant related absorption bands but clearly shifts the absorption edge as one expects for a solid-solution crystal Ga2(1-x)Al2xO3 still in the monoclinic phase. For the highest doping concentration (Ga1.9Al0.1O3) we estimate an increase of the energy gap by 0.11 eV.

Fabrication and comparison of PMN-PT single crystal, PZT and PZT-based 1-3 composite ultrasonic transducers for NDE applications.

Science.gov (United States)

Kim, Ki-Bok; Hsu, David K; Ahn, Bongyoung; Kim, Young-Gil; Barnard, Daniel J

2010-08-01

This paper describes fabrication and comparison of PMN-PT single crystal, PZT, and PZT-based 1-3 composite ultrasonic transducers for NDE applications. As a front matching layer between test material (Austenite stainless steel, SUS316) and piezoelectric materials, alumina ceramics was selected. The appropriate acoustic impedance of the backing materials for each transducer was determined based on the results of KLM model simulation. Prototype ultrasonic transducers with the center frequencies of approximately 2.25 and 5MHz for contact measurement were fabricated and compared to each other. The PMN-PT single crystal ultrasonic transducer shows considerably improved performance in sensitivity over the PZT and PZT-based 1-3 composite ultrasonic transducers. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Growth and optical characterizations on 3-aminophenol perchlorate (3-AMPP) crystal

Energy Technology Data Exchange (ETDEWEB)

Boopathi, K., E-mail: ramasamyp@ssn.edu.in; Ramasamy, P., E-mail: ramasamyp@ssn.edu.in [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam-603110 (India)

2014-04-24

A single crystal of organic nonlinear optical material 3-aminophenol perchlorate (3-AMP) was successfully grown by the slow evaporation solution method. Single-crystal X-ray diffractrometer was utilized to measure unit cell parameters and to confirm lattice parameter. 3-aminophenol perchlorate belongs to monoclinic space group P2{sub 1}. The optical transparency window in the UV-vis-NIR region is found to be good for nonlinear optical applications second harmonic studies were carried out. The second harmonic output intensity was tested using the Kurtz and Perry powder method and was found to be 1.1 times that of potassium dihydrogen phosphate (KDP)

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

International Nuclear Information System (INIS)

Kanamori, Y.; Shiohara, Y.

1996-01-01

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

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

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-11-15

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

Organic field-effect transistors using single crystals

Directory of Open Access Journals (Sweden)

Tatsuo Hasegawa and Jun Takeya

2009-01-01

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

Crystal ball single event display

International Nuclear Information System (INIS)

Grosnick, D.; Gibson, A.; Allgower, C.; Alyea, J.; Argonne National Lab., IL

1997-01-01

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

Mechanical characterization of magnesium aluminate MgO·nAl2O3 spinel single crystals irradiated with Cu- ions

International Nuclear Information System (INIS)

Ohmura, Takahito; Lee, Chi-Gyu; Kishimoto, Naoki

2003-01-01

Ion-irradiation response of spinel single crystals was investigated using a nanoindentation technique. Specimens of stoichiometric (n=1) and non-stoichiometric (n=2.4) single crystals of MgO n(Al 2 O 3 ) spinel were irradiated with 60 keV Cu - ion at room temperature. Dose rate ranged from 1 to 100 μA/cm 2 , and a total dose was kept constant at 3x10 16 ions/cm 2 . Both plastic hardness and elastic modulus of all the irradiated specimens were softened. Radiation-induced swelling simultaneously occurred. Rutherford back scattering spectroscopy detected disordering of spinel crystalline structure. Accordingly, the radiation-induced softening and swelling are ascribed to accumulation of point defects associated with the disordering. In comparison between the stoichiometric and the non-stoichiometric specimens, the radiation-induced softening is suppressed in the non-stoichiometric composition. (author)

Tensile properties of electron-beam-welded single crystals of molybdenum

International Nuclear Information System (INIS)

Hiraoka, Yutaka; Okada, Masatoshi; Irie, Hirosada; Fujii, Tadayuki.

1987-01-01

The purpose of this study is to investigate the macro- and microstructures and the tensile properties of electron-beam-welded single crystals of molybdenum. The single-crystal sheets were prepared by means of secondary recrystallization. The welding was carried out by a melt-run technique. The weld metal had the same crystallographic orientation as the base metal, and no grain boundary was observed. However, many large weld pores were formed mostly along the weld bond. The strength and ductility of the welded joints of single crystals were almost the same as those of the base metal (''annealed'' single crystals). It is concluded that the joint efficiency of molybdenum single crystals at room temperature or above was excellent and nearly 100 %. (author)

Electroerosion impulse effect on W single crystal structure

International Nuclear Information System (INIS)

Aleshina, S.A.; Khvostikova, V.D.; Zolotykh, B.N.; Marchuk, A.I.

1977-01-01

The mechanism has been studied of brittle failure of single crystal tungsten on planes of crystallographic orientations [100], [110]; [111] in the process of electro-erosion machining by pulses of energies ranging from 1200 to 5000 μJ and of duration of 1 μs. It is shown that the electro-erosion machining of single crystal tungsten is characterized by the formation of a defect layer with a grid of microcracks which lie at a depth of approximately 80 μm. The appearance and the distribution of cracks on the surface of single crystals depends on the crystallogrpahic orientation

Crystalline perfection and mechanical investigations on vertical Bridgman grown Bismuth telluride (Bi_2Te_3) single crystals for thermoelectric applications

International Nuclear Information System (INIS)

Krishna, Anuj; Vijayan, N.; Singh, Budhendra; Thukral, Kanika; Maurya, K.K.

2016-01-01

High efficiency thermoelectric materials plays a vital role in power generation and refrigeration applications. Bismuth telluride (Bi_2Te_3) is one among them. In the present work single crystal of bismuth telluride was grown using vertical Bridgman technique. The phase of grown crystals was analysed using a powder X-ray diffractometer. Quality of the grown crystal was assessed by using high resolution X-ray diffractometer and observed that it is fairly good. Further mechanical investigations on grown crystal was carried out using nano-indentation technique and various mechanical properties like hardness, stiffness and Young’s modulus were evaluated. Observed results clearly indicate its suitability for thermoelectric applications.

Nanomechanical resonant structures in single-crystal diamond

OpenAIRE

Burek, Michael J.; Ramos, Daniel; Patel, Parth; Frank, Ian W.; Lončar, Marko

2013-01-01

With its host of outstanding material properties, single-crystal diamond is an attractive material for nanomechanical systems. Here, the mechanical resonance characteristics of freestanding, single-crystal diamond nanobeams fabricated by an angled-etching methodology are reported. Resonance frequencies displayed evidence of significant compressive stress in doubly clamped diamond nanobeams, while cantilever resonance modes followed the expected inverse-length-squared trend. Q-factors on the o...

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.

Temperature-dependent Raman spectra and electrical properties of 0.69Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.31PbTiO{sub 3} single crystals

Energy Technology Data Exchange (ETDEWEB)

Fang, Bijun [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou (China); Liu, Xing [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou (China); Chinese Academy of Sciences, Key Laboratory of Inorganic Function Material and Device, Shanghai (China); Li, Xiaobing; Zhao, Xiangyong; Luo, Haosu [Chinese Academy of Sciences, Key Laboratory of Inorganic Function Material and Device, Shanghai (China); Ding, Jianning [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou (China); Jiangsu University, School of Material Science and Engineering, Zhenjiang (China)

2016-09-15

The temperature-dependent Raman spectra and electrical properties of the 0.69Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.31PbTiO{sub 3} (0.69PMN-0.31PT) single crystals were investigated. Based on the group theory, the poled 0.69PMN-0.31PT single crystals belong to the monoclinic crystal system, which was confirmed by the room-temperature Raman spectra. The 0.69PMN-0.31PT single crystals experience successive structural phase transitions, i.e., a monoclinic-tetragonal (FE{sub M}-FE{sub T}) phase transition at T{sub M-T} and a tetragonal-cubic (FE{sub T}-P{sub C}) phase transition at T{sub m} determined by the dielectric measurement. Due to the enhancement of long-range order, their FE{sub M}-FE{sub T} phase transition becomes more obvious after the poling process. The wavenumbers and line widths of the 271, 502, 575, 795 cm{sup -1} Raman modes, and the intensity ratios of I{sub 271cm}{sup {sub -}{sub 1}}/I{sub 795cm}{sup {sub -}{sub 1}} and I{sub 502cm}{sup {sub -}{sub 1}}/I{sub 575cm}{sup {sub -}{sub 1}} exhibit obvious anomalies around T{sub M-T} and T{sub m}, which are closely related to the FE{sub M}-FE{sub T} and FE{sub T}-P{sub C} phase transitions. The temperature and electric field (E)-induced phase transitions are observed in the unipolar strain-E (S-E) curves. The converse piezoelectric constant (d{sub 33}), maximum strain value (S{sub max}%) and longitudinal electrostrictive coefficient (Q) increase considerably around the ferroelectric phase transition temperature T{sub M-T}. (orig.)

Single crystal spectrometer FOX at KENS

International Nuclear Information System (INIS)

Takahashi, M.

2001-01-01

Single crystal spectrometer FOX installed at H1 thermal neutron line on KENS has been renewed recently for the measurement of very weak scattering. We have installed a multidetector system of 36 linearly placed 3 He detectors with collimators instead of former four-circle diffractometer and scintillator detectors. Though the system is quite simple, a large two-dimensional reciprocal space is observed effectively with high S/N rate on new FOX. (author)

Hierarchical self-assembly of hexagonal single-crystal nanosheets into 3D layered superlattices with high conductivity

Science.gov (United States)

Tao, Yulun; Shen, Yuhua; Yang, Liangbao; Han, Bin; Huang, Fangzhi; Li, Shikuo; Chu, Zhuwang; Xie, Anjian

2012-05-01

While the number of man-made nano superstructures realized by self-assembly is growing in recent years, assemblies of conductive polymer nanocrystals, especially for superlattices, are still a significant challenge, not only because of the simplicity of the shape of the nanocrystal building blocks and their interactions, but also because of the poor control over these parameters in the fabrication of more elaborate nanocrystals. Here, we firstly report a facile and general route to a new generation of 3D layered superlattices of polyaniline doped with CSA (PANI-CSA) and show how PANI crystallize and self-assemble, in a suitable single solution environment. In cyclohexane, 1D amorphous nanofibers transformed to 1D nanorods as building blocks, and then to 2D single-crystal nanosheets with a hexagonal phase, and lastly to 3D ordered layered superlattices with the narrowest polydispersity value (Mw/Mn = 1.47). Remarkably, all the instructions for the hierarchical self-assembly are encoded in the layered shape in other non-polar solvents (hexane, octane) and their conductivity in the π-π stacking direction is improved to about 50 S cm-1, which is even higher than that of the highest previously reported value (16 S cm-1). The method used in this study is greatly expected to be readily scalable to produce superlattices of conductive polymers with high quality and low cost.While the number of man-made nano superstructures realized by self-assembly is growing in recent years, assemblies of conductive polymer nanocrystals, especially for superlattices, are still a significant challenge, not only because of the simplicity of the shape of the nanocrystal building blocks and their interactions, but also because of the poor control over these parameters in the fabrication of more elaborate nanocrystals. Here, we firstly report a facile and general route to a new generation of 3D layered superlattices of polyaniline doped with CSA (PANI-CSA) and show how PANI crystallize and

Growth by the μ-PD Method and Visible Laser Operation of a Single-Crystal Fiber of Pr3+:KY3F10

Directory of Open Access Journals (Sweden)

Jun Shu

2017-07-01

Full Text Available We report on the first growth, spectroscopy, and visible laser operation of a single-crystal fiber (SCF of KY3F10 (KYF grown by the micro-pulling-down (μ-PD method, doped with Pr3+ ions. This material has a cubic lattice, which makes it appealing for use in the industry. However, KYF crystals are considered difficult to grow with high optical quality, even with well-established methods. Nevertheless, we grew a 50-mm-long SCF of Pr:KYF, which was transparent in its inner part. We studied the spectroscopic features of it in comparison with existing literature and with samples of the same crystal grown by the Czochralski method, and we did not notice any large differences. These characterizations confirmed that is indeed possible to grow high-quality crystals of Pr:KYF by the μ-PD method. Unfortunately, the crystal proved to be more brittle than typical KYF and especially difficult to polish, leading to rough and irregular facets, as evidenced by transmission measurements. Despite these issues, we obtained continuous-wave laser operation in the orange, red, and deep red regions, using a sample carved from the SCF as active medium and an InGaN-based laser diode as pump source, though with lower performances than in existing reports on this crystal.

Analysis of the quadrupolar coupling effect on the line intensities using single-crystal nutation NMR in α-Al2O3 crystals

International Nuclear Information System (INIS)

Woo, Ae Ja; Cho, So Hyun; Han, Duk Young

2000-01-01

With 1D-nutation NMR for a spin I = 5/2 system, the relative line intensities of central and the inner- and outer-satellite transitions are calculated as functions of quadrupolar coupling ω Q and rf pulse strength ω rf . Experimentally measured line intensities including both central and satellites are used to extract the values of ω Q and ω rf from nonlinear least-squares fits. The method is illustrated in α-Al 2 O 3 crystals (ruby and corundum) with the single-crystal 27 Al nutation NMR spectra. As a result, the new feature that the rf pulse strength shows reduced effect on the satellite transition lines according to the quadrupolar coupling is discussed by using fictitious spin-1/2 operator

Unidirectional growth and characterization of L-arginine monohydrochloride monohydrate single crystals

International Nuclear Information System (INIS)

Sangeetha, K.; Babu, R. Ramesh; Bhagavannarayana, G.; Ramamurthi, K.

2011-01-01

Highlights: → L-Arginine monohydrochloride monohydrate (LAHCl) single crystal was grown successfully by unidirectional solution growth method for the first time. → High crystalline perfection was observed for UDS grown crystal compared to CS grown crystal. → The optical transparency and mechanical stability are high for UDS grown LAHCl single crystal. → Optical birefringence measurement on this material. → The piezoelectric resonance frequencies observation - first time observation on this material. - Abstract: L-Arginine monohydrochloride monohydrate (LAHCl) single crystals were grown successfully by conventional and unidirectional solution growth methods. The crystalline perfection of grown crystals was analyzed by high-resolution X-ray diffraction. The linear optical transmittance, mechanical stability of conventional and unidirectional grown LAHCl single crystals were analyzed and compared along (0 0 1) plane. The refractive index and birefringence of LAHCl single crystals were also measured using He-Ne laser source. From the dielectric studies, piezoelectric resonance frequencies were observed in kHz frequency range for both conventional and unidirectional grown LAHCl single crystals along (0 0 1) plane.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Magnetic excitations of single-crystal PrBa₂Cu₃O_6.2

DEFF Research Database (Denmark)

Lister, S.J.S.; Boothroyd, A.T.; Andersen, N.H.

2000-01-01

Measurements of the low-energy magnetic excitations in single-crystal PrBa2Cu3O6.2, and in YBa2Cu3O6.2 for comparison, have been performed using inelastic neutron scattering. An excitation with weak dispersion is seen, which is compared to a spin-wave model based on the lowest lying crystal field...

Solution growth of single crystal methylammonium lead halide perovskite nanostructures for optoelectronic and photovoltaic applications.

Science.gov (United States)

Fu, Yongping; Meng, Fei; Rowley, Matthew B; Thompson, Blaise J; Shearer, Melinda J; Ma, Dewei; Hamers, Robert J; Wright, John C; Jin, Song

2015-05-06

Understanding crystal growth and improving material quality is important for improving semiconductors for electronic, optoelectronic, and photovoltaic applications. Amidst the surging interest in solar cells based on hybrid organic-inorganic lead halide perovskites and the exciting progress in device performance, improved understanding and better control of the crystal growth of these perovskites could further boost their optoelectronic and photovoltaic performance. Here, we report new insights on the crystal growth of the perovskite materials, especially crystalline nanostructures. Specifically, single crystal nanowires, nanorods, and nanoplates of methylammonium lead halide perovskites (CH3NH3PbI3 and CH3NH3PbBr3) are successfully grown via a dissolution-recrystallization pathway in a solution synthesis from lead iodide (or lead acetate) films coated on substrates. These single crystal nanostructures display strong room-temperature photoluminescence and long carrier lifetime. We also report that a solid-liquid interfacial conversion reaction can create a highly crystalline, nanostructured MAPbI3 film with micrometer grain size and high surface coverage that enables photovoltaic devices with a power conversion efficiency of 10.6%. These results suggest that single-crystal perovskite nanostructures provide improved photophysical properties that are important for fundamental studies and future applications in nanoscale optoelectronic and photonic devices.

Mesoporous Zeolite Single Crystals for Catalytic Hydrocarbon Conversion

DEFF Research Database (Denmark)

Schmidt, I.; Christensen, Claus H.; Kustova, Marina

2005-01-01

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

Crystallographic Investigations into Properties of Acentric Hybrid Perovskite Single Crystals NH(CH3)3SnX3(X = Cl, Br)

KAUST Repository

Dang, Yangyang; Zhong, Cheng; Zhang, Guodong; Ju, Dianxing; Wang, Lei; Xia, Shengqing; Xia, Haibing; Tao, Xutang

2016-01-01

substitute for the lead in the halides perovskites and solving the ambiguous crystal structures and phase transition of NH(CH3)3SnX3 (X = Cl, Br). Here, we report the bulk crystal growths and different crystal morphologies of orthorhombic hybrid perovskites

Resistivity distribution of silicon single crystals using codoping

Science.gov (United States)

Wang, Jong Hoe

2005-07-01

Numerous studies including continuous Czochralski method and double crucible technique have been reported on the control of macroscopic axial resistivity distribution in bulk crystal growth. The simple codoping method for improving the productivity of silicon single-crystal growth by controlling axial specific resistivity distribution was proposed by Wang [Jpn. J. Appl. Phys. 43 (2004) 4079]. Wang [J. Crystal Growth 275 (2005) e73] demonstrated using numerical analysis and by experimental results that the axial specific resistivity distribution can be modified in melt growth of silicon crystals and relatively uniform profile is possible by B-P codoping method. In this work, the basic characteristic of 8 in silicon single crystal grown using codoping method is studied and whether proposed method has advantage for the silicon crystal growth is discussed.

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.

Solar cell structure incorporating a novel single crystal silicon material

Science.gov (United States)

Pankove, Jacques I.; Wu, Chung P.

1983-01-01

A novel hydrogen rich single crystal silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystal silicon without out-gassing the hydrogen. The new material can be used to fabricate semiconductor devices such as single crystal silicon solar cells with surface window regions having a greater band gap energy than that of single crystal silicon without hydrogen.

Numerical study of slip system activity and crystal lattice rotation under wedge nanoindents in tungsten single crystals

Science.gov (United States)

Volz, T.; Schwaiger, R.; Wang, J.; Weygand, S. M.

2018-05-01

Tungsten is a promising material for plasma facing components in future nuclear fusion reactors. In the present work, we numerically investigate the deformation behavior of unirradiated tungsten (a body-centered cubic (bcc) single crystal) underneath nanoindents. A finite element (FE) model is presented to simulate wedge indentation. Crystal plasticity finite element (CPFE) simulations were performed for face-centered and body-centered single crystals accounting for the slip system family {110} in the bcc crystal system and the {111} slip family in the fcc system. The 90° wedge indenter was aligned parallel to the [1 ¯01 ]-direction and indented the crystal in the [0 1 ¯0 ]-direction up to a maximum indentation depth of 2 µm. In both, the fcc and bcc single crystals, the activity of slip systems was investigated and compared. Good agreement with the results from former investigations on fcc single crystals was observed. Furthermore, the in-plane lattice rotation in the material underneath an indent was determined and compared for the fcc and bcc single crystals.

Micro-Raman study of the microheterogeneity in the MA-MC phase transition in 0.67PbMg1/3Nb2/3O3-0.33PbTiO3 single crystal

KAUST Repository

Yang, Y.

2011-04-20

Polarized Raman spectroscopy has been employed to investigate the evolution of the microstructure of 0.67PbMg1/3Nb2/3O3-0.33PbTiO3 (PMN-33%PT) single crystal in the temperature range from −195 to 300 °C. The M A-M C-cubic transition sequence was observed in the microareas with M A-type (space group Cm) and M C-type (space group Pm) monoclinic structures. Interestingly, the M A-M Cphase transition temperature exhibited remarkable microareal dependence due to the spatial inhomogeneity of polar nanoregions (PNRs). The M C-cubic phase transition took place at 155 °C in both microareas, which consisted well with previous reports. These results reveal that the phase transition in PMN-33%PT single crystal is closely related with the thermal dynamics of PNRs, which will be useful for understanding the microheterogeneity in this compound.

Anomalous magnetic properties of 7 nm single-crystal Co3O4 nanowires

Science.gov (United States)

Lv, Ping; Zhang, Yan; Xu, Rui; Nie, Jia-Cai; He, Lin

2012-01-01

We present a study of magnetic properties of single-crystal Co3O4 nanowires with diameter about 7 nm. The nanowires expose (111) planes composed of plenty of Co3+ cations and exhibit two order temperatures at 56 K (TN of wire cores) and 73 K (order temperature of wire shells), which are far above TN = 40 K of bulk Co3O4. This novel behavior is attributed to symmetry breaking of surface Co3+ cations and magnetic proximity effect. The nanowire shells show macroscopic residual magnetic moments. Cooling in a magnetic field, a fraction of the residual moments are tightly pinned to the antiferromagnetic lattice, which results in an obvious horizontal and vertical shift of hysteresis loop. Our experiment demonstrates that the exchange bias field HE and the pinned magnetic moments Mpin follow a simple expression HE = aMpin with a a constant.

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

Nanosecond X-ray detector based on high resistivity ZnO single crystal semiconductor

Energy Technology Data Exchange (ETDEWEB)

Zhao, Xiaolong; He, Yongning, E-mail: yongning@mail.xjtu.edu.cn; Peng, Wenbo; Huang, Zhiyong; Qi, Xiaomeng; Pan, Zijian; Zhang, Wenting [School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Chen, Liang; Liu, Jinliang; Zhang, Zhongbing; Ouyang, Xiaoping [Radiation Detection Research Center, Northwest Institute of Nuclear Technology, Xi' an 710024 (China)

2016-04-25

The pulse radiation detectors are sorely needed in the fields of nuclear reaction monitoring, material analysis, astronomy study, spacecraft navigation, and space communication. In this work, we demonstrate a nanosecond X-ray detector based on ZnO single crystal semiconductor, which emerges as a promising compound-semiconductor radiation detection material for its high radiation tolerance and advanced large-size bulk crystal growth technique. The resistivity of the ZnO single crystal is as high as 10{sup 13} Ω cm due to the compensation of the donor defects (V{sub O}) and acceptor defects (V{sub Zn} and O{sub i}) after high temperature annealing in oxygen. The photoconductive X-ray detector was fabricated using the high resistivity ZnO single crystal. The rise time and fall time of the detector to a 10 ps pulse electron beam are 0.8 ns and 3.3 ns, respectively, indicating great potential for ultrafast X-ray detection applications.

High-quality single crystals for neutron experiments

Indian Academy of Sciences (India)

studies and our collaborative research projects with other UK and international groups will be discussed. Keywords. Crystal growth; floating zone method; neutron scattering. ... of single crystals of new materials is a highly competitive business.

Pyroelectric properties of phosphoric acid-doped TGS single crystals

Energy Technology Data Exchange (ETDEWEB)

Saxena, Aparna; Fahim, M; Gupta, Vinay; Sreenivas, K [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

2003-12-21

Pyroelectric properties of phosphoric acid (H{sub 3}PO{sub 4})-doped triglycine sulfate (TGSP) single crystals grown from solutions containing 0.1-0.5 mol of H{sub 3}PO{sub 4} have been studied. Incorporation of H{sub 3}PO{sub 4} into the crystal lattice is found to induce an internal bias field (E{sub b}) and is observed through the presence of a sustained polarization and pyroelectricity beyond the transition temperature. The internal bias field has been estimated theoretically by fitting the experimentally measured data on temperature dependence of the pyroelectric coefficient ({lambda}), dielectric constant ({epsilon}') and polarization (P). A high E{sub b} value in the range 9 x 10{sup 3}-15.5 x 10{sup 4} V m{sup -1} is obtained for crystals grown with 0.1-0.5 mol of H{sub 3}PO{sub 4} in the solution, and a specific concentration of 0.2-0.25 mol of H{sub 3}PO{sub 4} in the solution during crystal growth is found to be optimum for a high figure of merit for detectivity, F{sub d} = 428 {mu}C m{sup -2} K{sup -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.

Gallium arsenide single crystal solar cell structure and method of making

Science.gov (United States)

Stirn, Richard J. (Inventor)

1983-01-01

A production method and structure for a thin-film GaAs crystal for a solar cell on a single-crystal silicon substrate (10) comprising the steps of growing a single-crystal interlayer (12) of material having a closer match in lattice and thermal expansion with single-crystal GaAs than the single-crystal silicon of the substrate, and epitaxially growing a single-crystal film (14) on the interlayer. The material of the interlayer may be germanium or graded germanium-silicon alloy, with low germanium content at the silicon substrate interface, and high germanium content at the upper surface. The surface of the interface layer (12) is annealed for recrystallization by a pulsed beam of energy (laser or electron) prior to growing the interlayer. The solar cell structure may be grown as a single-crystal n.sup.+ /p shallow homojunction film or as a p/n or n/p junction film. A Ga(Al)AS heteroface film may be grown over the GaAs film.

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

International Nuclear Information System (INIS)

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

2006-01-01

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

Evolution of electrical properties and domain configuration of Mn modified Pb(In1/2Nb1/2)O3-PbTiO3 single crystals

Science.gov (United States)

Qiao, Huimin; He, Chao; Yuan, Feifei; Wang, Zujian; Li, Xiuzhi; Liu, Ying; Guo, Haiyan; Long, Xifa

2018-04-01

The acceptor doped relaxor-based ferroelectric materials are useful for high power applications such as probes in ultrasound-guided high intensity focused ultrasound therapy. In addition, a high Curie temperature is desired because of wider temperature usage and improved temperature stability. Previous investigations have focused on Pb(Mg1/3Nb2/3)O3-PbTiO3 and Pb(Zn1/3Nb2/3)O3-PbTiO3 systems, which have a ultrahigh piezoelectric coefficient and dielectric constant, but a relatively low Curie temperature. It is desirable to study the binary relaxor-based system with a high Curie temperature. Therefore, Pb(In1/2Nb1/2)O3-PbTiO3 (PINT) single crystals were chosen to study the Mn-doped influence on their electrical properties and domain configuration. The evolution of ferroelectric hysteresis loops for doped and virgin samples exhibit the pinning effect in Mn-doped PINT crystals. The relaxation behaviors of doped and virgin samples are studied by fit of the modified Curie-Weiss law and Volgel-Fucher relation. In addition, a short-range correlation length was fitted to study the behavior of polar nanoregions based on the domain configuration obtained by piezoresponse force microscopy. Complex domain structures and smaller short-range correlation lengths (100-150 nm for Mn-doped PINT and >400 nm for pure PINT) were obtained in the Mn-doped PINT single crystals.

Growth, structure, Hirshfeld surface and spectroscopic properties of 2-amino-4-hydroxy-6-methylpyrimidinium-2,3-pyrazinedicorboxylate single crystal

Science.gov (United States)

Faizan, Mohd; Alam, Mohammad Jane; Afroz, Ziya; Rodrigues, Vítor Hugo Nunes; Ahmad, Shabbir

2018-03-01

The present work is focused on the crystal structure, vibrational spectroscopy and DFT calculations of hydrogen bonded 2,3-pyrazinedicorboxylic acid and 2-amino-4-hydroxy-6-methylpyrimidine (PDCA-.AHMP+) crystal. The crystal structure has been determined using single crystal X-ray diffraction analysis which shows that the crystal belongs to monoclinic space group P21/n. The PDCA-.AHMP+ crystal has been characterized by FTIR, FT-Raman and FT-NMR spectroscopic techniques. The FTIR and FT-Raman spectra of the complex have unique spectroscopic feature as compared with those of the starting material to confirm salt formation. The theoretical vibrational studies have been performed to understand the modes of the vibrations of asymmetric unit of the complex by DFT methods. Hirschfeld surface and 2D fingerprint plots analyses were carried out to investigate the intermolecular interactions and its contribution in the building of PDCA-.AHMP+ crystal. The experimental and simulated 13C and 1H NMR studies have assisted in structural analysis of PDCA-.AHMP+ crystal. The electronic spectroscopic properties of the complex were explored by the experimental as well as theoretical electronic spectra simulated using TD-DFT/IEF-PCM method at B3LYP/6-311++G (d,p) level of theory. In addition, frontier molecular orbitals, molecular electrostatic potential map (MEP) and nonlinear optical (NLO) properties using DFT method have been also presented.

Scanning/friction force microscopy study of YBa2Cu3O7-δ single crystals grown in BaZrO3 crucibles

International Nuclear Information System (INIS)

Lang, H.P.; Jess, P.; Hubler, U.

1996-01-01

Very pure YBa 2 Cu 3 O 7-δ (YBCO) single crystals grown in BaZrO 3 crucibles are studied in the as-grown and the oxidized state by scanning force (SFM), friction force (FFM) and scanning tunneling microscopies (STM). The images show clean terraces with step-heights of one unit cell along YBCO(001), i.e. 1.2 nm. Only close to step edges is material contrast observed by FFM indicating traces of flux. Some crystal surfaces exhibit over-layer features, such as star-like, ribbon-like and checkerboard-like structures, which exhibit friction contrast implying the presence of different materials on the surface. Tunneling spectroscopy at 4-7 K in high vacuum reveals a superconducting energy gap of 2Δ ∼ 26 meV

Crystal plasticity study of single crystal tungsten by indentation tests

International Nuclear Information System (INIS)

Yao, Weizhi

2012-01-01

Owing to its favorable material properties, tungsten (W) has been studied as a plasma-facing material in fusion reactors. Experiments on W heating in plasma sources and electron beam facilities have shown an intense micro-crack formation at the heated surface and sub-surface. The cracks go deep inside the irradiated sample, and often large distorted areas caused by local plastic deformation are present around the cracks. To interpret the crack-induced microscopic damage evolution process in W, one needs firstly to understand its plasticity on a single grain level, which is referred to as crystal plasticity. In this thesis, the crystal plasticity of single crystal tungsten (SCW) has been studied by spherical and Berkovich indentation tests and the finite element method with a crystal plasticity model. Appropriate values of the material parameters included in the crystal plasticity model are determined by fitting measured load-displacement curves and pile-up profiles with simulated counterparts for spherical indentation. The numerical simulations reveal excellent agreement with experiment. While the load-displacement curves and the deduced indentation hardness exhibit little sensitivity to the indented plane at small indentation depths, the orientation of slip directions within the crystals governs the development of deformation hillocks at the surface. It is found that several factors like friction, indentation depth, active slip systems, misoriented crystal orientation, misoriented sample surface and azimuthal orientation of the indenter can affect the indentation behavior of SCW. The Berkovich indentation test was also used to study the crystal plasticity of SCW after deuterium irradiation. The critical load (pop-in load) for triggering plastic deformation under the indenter is found to depend on the crystallographic orientation. The pop-in loads decrease dramatically after deuterium plasma irradiation for all three investigated crystallographic planes.

Magnetotransport study of topological superconductor Cu0.10Bi2Se3 single crystal

Science.gov (United States)

Li, M. T.; Fang, Y. F.; Zhang, J. C.; Yi, H. M.; Zhou, X. J.; Lin, C. T.

2018-03-01

We report a magnetotransport study of vortex-pinning in Cu0.10Bi2Se3 single crystal. The sample is demonstrated to be in clean limit and absent of Pauli spin-limiting effect. Interestingly, the resistivity versus magnetic field shows an anomalously pronounced increase when approaching the superconducting-normal state boundary for both {{B}app}\\parallel ab and {{B}app}\\parallel c configurations. We have investigated the flux-flowing behavior under various magnetic fields and temperatures, enabling us to establish its anisotropic vortex phase diagram. Our results suggest the Cu0.10Bi2Se3 can be served as one unique material for exploring exotic surface vortex states in topological superconductors.

Photoluminescence properties of boron doped InSe single crystals