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1.
Langasite (La3Ga5SiO14, LGS) and its isomorphs, have attracted much attention for their potential for surface acoustic wave (SAW) and bulk acoustic wave (BAW) applications. Among these homologous compounds, Sr3Ga2Ge4O14 (SGG) attracted our attention due to its superior piezoelectric properties and lower growth temperature. In this work, SGG single crystal has been grown successfully by the vertical Bridgman method with crucible-sealing technique. SGG wafers of 2 in. have been fabricated. The basic physical properties of SGG crystals were measured. The results demonstrate that piezoelectric and mechanical properties of SGG crystals are better than that of LGS crystal and it is expected to be a potential substrate material for SAW and BAW applications. 相似文献
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Using 100Pd/100Rh probes, perturbed angular correlation measurements were performed to study Pd-related defects in Si as a function of dopant concentration and dopant type. Pd-vacancy and Pd-B complexes were identified by their characteristic electric field gradients in highly doped n- and p-type Si, respectively. Both pairs exhibited a T3/2 temperature dependence of their electric field gradients. 相似文献
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A. E. Nosenko R. E. Leshchuk B. V. Padlyak A. A. Sel’skii 《Physics of the Solid State》1997,39(6):938-942
Studies of EPR spectra, additional optical absorption, and the kinetics of buildup and decay of radiation-induced paramagnetic
centers in compositionally disordered crystals of trigonal Ca-gallogermanate are reported. The parameters of the spin-Hamiltonian
describing the observed room-temperature EPR spectra are determined. It is established that the radiation-induced paramagnetic
centers in Ca3Ga2Ge4O14 crystals are O− centers in common 6g sites stabilized by the Ge4+ vacancy in tetrahedral 2d sites.
Fiz. Tverd. Tela (St. Petersburg) 39, 1044–1049 (June 1997) 相似文献
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D. V. Roshchupkin D. V. Irzhak O. A. Plotitsyna R. R. Fakhrtdinov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(6):947-950
Ca3TaGa3Si2O14 (CTGS) crystals are a new promising material from the lanthanum-gallium silicate family, which can be employed in high-temperature sensors and other acoustoelectronic devices. The structural perfection and acoustic properties of CTGS crystals have been investigated via X-ray topography and diffractometry at the BESSY II synchrotron radiation source in the geometry of a double-crystal X-ray diffractometer. 相似文献
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D. V. Roshchupkin D. V. Irzhak O. A. Plotitsyna R. R. Fakhrtdinov O. A. Buzanov A. P. Sergeev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(3):490-493
A new promising piezoelectric material Ca3TaGa3Si2O14 (CTGS) has been grown using the Czochralski method. Its unit-cell parameters have been determined by means of the X-ray phase analysis method. The X-ray diffractometry method was used to study the crystal acoustic properties; the velocities of surface acoustic wave propagation were measured for the first time and the power flow angles were determined. 相似文献
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The photoconductivity and electrical conductivity, the thermally stimulated polarization and depolarization currents, the
permittivity, and the dielectric losses of noncentrosymmetric Ca3Ga2Ge4O14 crystals of a structural type of trigonal calcium gallogermanate (CGG) have been studied for the first time in the temperature
interval 100–700 K in air and in vacuum. The features of the temperature behavior of CGG are associated, in particular, with
the effect of electrically active defects and partial disordering of the cation sublattice of the crystal structure, which
generates polar formations (dipoles) of several kinds. Certain parameters of the electromigration and of the electrically
active defects that cause charge-relaxation and polarization effects are determined. It is concluded that dipole relaxation
in CGG makes it a new representative of a class of materials in which reorientation of the dipoles as a system of mobile local
distortions of the structure has a substantial effect on the physical properties.
Fiz. Tverd. Tela (St. Petersburg) 39, 871–876 (May 1997) 相似文献
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Dmitry Roshchupkin Luc Ortega Olga Plotitcyna Alexei Erko Ivo Zizak Dmitry Irzhak Rashid Fahrtdinov Oleg Buzanov 《Applied Physics A: Materials Science & Processing》2014,114(4):1105-1112
A five-component crystal of the lanthanum–gallium silicate family Ca3TaGa3Si2O14 (CTGS) was grown by the Czochralski method. The CTGS crystal, like the langasite crystal (La3Ga5SiO14, LGS), possesses unique temperature properties and the fewer number of the Ga atoms in the unit cell makes the density much lower and, consequently, increases the velocity of acoustic wave propagation. The unit-cell parameters were determined by the powder diffraction technique. The defects in the CTGS crystal structure were studied by X-ray topography, which enables the visualization of growth banding characteristics of crystals grown by the Czochralski method. Surface acoustic wave (SAW) propagation in the CTGS crystal was investigated by the high-resolution X-ray diffraction method on the BESSY II synchrotron radiation source. The velocities of propagation and power flow angles of SAWs in the Y- and X-cuts of the CTGS crystal were determined from the X-ray diffraction spectra. 相似文献
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In this article, we have reported emission characteristics of Eu2+ activated Sr12Al10.6Si3.4O32Cl5.4 and Ca12Al10.6Si3.4O32Cl5.4 phosphors, prepared by combustion synthesis. The PL excitation was monitored at two different wavelengths 254 nm (mercury excitation) and 354 nm (mercury free excitation), which shows broad-blue emission bands at 432 nm, and 438 nm for 354 nm excitation wavelength. Under mercury excitation at 254 nm it shows emission wavelengths at 470 nm, 589 nm, 592 nm, and 617 nm for the prepared Sr12Al10.6Si3.4O32Cl5.4 and Ca12Al10.6Si3.4O32Cl5.4 phosphors. Further it was characterized by XRD, for the investigation of phase and purity of the phosphors. Thermal degradation of the phosphors was also studied at different temperatures. 相似文献
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Results of investigations of spectroscopic properties of Ca3Ga2Ge4O14 single crystals activated with Sm3+ ions are reported. It is shown that Sm3+ ions in Ca3Ga2Ge4O14 form a type of activator quasicenter whose nature is associated with disordering of the matrix.
I. Franko Lvov State University, 50, Dragomanov St., Lvov, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol.
65, No. 2, pp. 296–298, March–April, 1998. 相似文献
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为了研究CNGS晶体的结构,构造了Ca3NbGa2SiO12和Ca3NbGaSi2O12两个团簇模型,对其构型进行优化并计算了振动频率.利用Raman光谱技术测量了该晶体的Raman光谱,依据理论计算结果对测得的Raman光谱进行了指认,讨论了CNGS晶体的层状结构和压电性能. 相似文献
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The phonon spectra, Born effective charges, and dielectric constants ε∞ for the □AlF3, □GaF3, and □InF3 crystals (where □ is a vacancy) have been calculated in terms of the generalized Gordon-Kim method. The calculated spectra of lattice vibrations contain no imaginary vibrational frequencies. This suggests the stability of the cubic phase of these compounds but contradicts the observable structural transition from cubic to rhombohedral phase. It is assumed that such a transition in the □AlF3, □GaF3, and □InF3 crystals is brought about by structural defects. The calculated spectrum of lattice vibrations of the “completely defective” crystal M□F3 (M = Al, Ga, and In) indicates a strong instability of the cubic phase. Within the mean crystal approximation, the cubic phase of M x M 1?x F3 crystals appears to be unstable at small x≤0.05. 相似文献
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Ca3Al2M3O12(M=Si,Ge)石榴石中Ce^3+离子的荧光光谱 总被引:7,自引:0,他引:7
本文研究了Ca3Al2M3O12(M=Si,Ge)石榴石中Ge^3+离子的荧光光谱。在这两种石榴石中,Ce^3+的发射光谱均为Ce^3+的5d→4f能级跃迁发射宽谱带,但有很大差异。在锗酸盐中,Ce^3+的发射强度很弱,而在硅酸盐中发射强,295和77K下在Ca3Al2Si3O12中Ce^3+的荧光寿命分别为46和49ns。Gd^3+和助溶剂的引入可提高Ce^3+的发射强度。 相似文献
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RE Baumbach X Lu F Ronning JD Thompson ED Bauer 《J Phys Condens Matter》2012,24(32):325601, 1-325601, 7
The temperature (T)-pressure (P) phase diagrams are reported for the tetragonal layered compounds CeRu(2)Al(2)B, CeRu(2)Ga(2)B, and CeRu(2)Ga(2)C, studied by magnetization, specific heat and electrical resistivity. These systems exhibit localized 4f magnetic ordering with ferromagnetic ground states at T(C)?=?12.8?K, 16.3?K, and 17.2?K, respectively. Chemical and applied pressure both increase T(C) in a similar manner. The evolution of properties with chemical and applied pressure suggests that these phase diagrams may be connected in a Doniach-like picture where CeRu(2)Al(2)B is furthest from the possible quantum phase transition and CeRu(2)Ga(2)C is the nearest. 相似文献
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Optical and scintillation properties of Sr3NbGa3Si2O14 [SNGS] and Sr3TaGa3Si2O14 [STGS] single crystals with the langasite-type crystal structure were investigated as a novel scintillator materials. In the transmittance spectra of the SNGS and STGS polished specimens, absorption peaks around 380 and 505 nm were observed and the absorptions are considered to be attributable to the excess oxygen in the crystals. An emission peak around 420 nm was observed in the X-ray radioluminescence spectrum of the SNGS crystal. On the other hand, there was an emission peak around 335 nm in the X-ray radioluminescence spectrum of the STGS crystal. 相似文献
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《Physics letters. A》2006,360(2):339-343
First principle calculations of structural and elastic properties of ZnAl2O4, ZnGa2O4 and ZnIn2O4 compounds are presented, using the pseudo-potential plane-waves approach based on density functional theory, within the generalized gradient approximation GGA. The lattice constants and internal parameters are in good agreement with the available experimental results. Young's modulus, Poisson ratio, bulk modulus, elastic constants and their pressure dependence are also calculated. As the experimental elastic constants are not available hence our results were only compared with the available theoretical values obtained at equilibrium volume. 相似文献