共查询到20条相似文献,搜索用时 15 毫秒
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V. Gh. Mirzoyan A. A. Yeghiazaryan E. H. Baghdasaryan P. V. Mirzoyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2007,42(6):235-239
Laue-geometry X-ray diffraction has been studied experimentally in quartz crystals excited by bulk acoustic waves. These waves deform reflecting atomic planes, which leads to spatial modulation of diffracted beams. We show that in the beam section perpendicular to the diffraction vector the intensity stripes appear whose number depends on the order of harmonic of the excited acoustic field. The intensity of appearing fringes depends on the amplitude of alternative voltage applied to the crystal. 相似文献
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劳厄对晶体衍射的发现 总被引:1,自引:0,他引:1
介绍了劳厄提出晶体衍射思想的科学背景及当时的实验过程,并探讨在劳厄发现晶体衍射的过程中其科学思想的形成及X射线晶体衍射的发现带给我们的启示及影响. 相似文献
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利用瞬态X射线衍射技术对LiF单晶沿晶向[100]方向冲击加载的晶格变形进行了诊断研究。实验在神光Ⅱ装置的球形靶上进行,北四路激光驱动Cu靶获得的类He线作为X射线背光源,第九路为加载光源,对大小为7 mm7 mm、厚300 m的受激光加载的LiF单晶衍射,实验获得了LiF单晶晶面(200)压缩和未压缩状态的衍射信号。实验结果表明:LiF单晶在激光沿[100]方向冲击加载下,晶格发生了弹性变形,(200)晶面间距变小,衍射线上移,晶格压缩量为11%;该瞬态X射线衍射技术可用于冲击加载下的微观动态响应特性测量。 相似文献
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In this work, bulk acoustic wave propagation properties of langasite single crystal excited by lateral electric field have been investigated. Three important crystal cuts have been identified for different operational modes of lateral field excitation (LFE) on langasite substrate, namely the (yxl)65o (pure-LFE mode), (yxl)45o (quasi-LFE mode), and (yxl)0o (pseudo-LFE mode). Devices on langasite substrate with the above cuts were fabricated and tested, and the experimental results agree well with the theoretical analysis. It is found that a pure thickness shear mode exists in the (yxl)65o langasite LFE device with the bare side facing liquid, and no spurious mode is found due to its moderately large piezoelectric coupling factor. In addition, (yxl)0o langasite LFE device is also found suitable for liquid phase sensing applications. 相似文献
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Abstract A new diamond anvil cell and a helium flow cryostat have been developed for X-ray diffraction on single crystals at low temperatures and high pressures using white radiation of a synchrotron beam. This novel instrument especially enables continuous change of temperature and pressure of the sample without any adjustment of alignment. Automatic search for diffraction peaks can be performed since less than 30 pm eccentricity can be maintained during the rotation of the cell in the cryostat and the rotation of the cryostat on the goniometer head. The minimum temperature reached is 46 K. Measurements of solid 4He at 11.8 GPa are presented which confirm the stability of the hcp phase on this isobar. 相似文献
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Slavil Slavov 《Applied Physics A: Materials Science & Processing》1991,52(3):184-187
This paper presents some important relationships relating to frequencies in contoured AT-cut quartz resonators. It is shown that frequency interval relations are not affected by the piezoelement geometry but are functionally related solely to the indices of the Hermite functions. According to the analysis of trapped-energy resonators, an X-ray technique for predicting the frequency spectrum can be derived. It is based on the use of X-ray patterns of two wave motions and enables one to determine the whole frequency spectrum in the vicinity of any odd harmonic overtone of vibration. Two contoured resonator analyses show that the X-ray topography predictions are in good agreement with experimental data. 相似文献
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We have derived analytic expressions for the deflection as well as transmitted fraction of monochromatic neutrons forward
diffracted by a single crystal prism. In the vicinity of a Bragg reflection, the neutron deflection deviates sharply from
that for an amorphous prism, exhibiting three orders of magnitude greater sensitivity to the incidence angle. We have measured
the variation of neutron deflection and transmission across a Bragg reflection, for several single crystal prisms. The results
agree well with theory.
相似文献
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The high-pressure behaviors of SmFeO3 are investigated by angle-dispersive synchrotron X-ray powder diffraction under a pressure of up to 40.3 GPa at room temperature. The crystal structure of SmFeO3 remains stable at up to the highest pressure. The different pressure coefficients of the normalized axial compressibility are obtained to be βa = 0.60 × 10-3 GPa-1,βb = 0.79 × 10-3 GPa-1, βc = 1.28 × 10-3 GPa- 1, and the bulk modulus (B0) is determined to be 293(3) GPa by fitting the pressure-volume data using the Birch-Murnaghan equation of state. Furthermore, the larger compressibility of the FeO6 octahedra suggests the evolution of the orthorhombic structure towards higher symmetry configuration at high pressures. 相似文献
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The VF3-type compounds MF3 with M = Fe and Ga have been studied by high-pressure energy-dispersive X-ray diffraction. The compression mechanism was found to be highly anisotropic for both compounds, with the c-axis showing little pressure dependence. The volume reduction is mainly achieved through coupled rotations of the MF6 octahedra around the c-axis, which reduces the length of the a-axis. The compression mechanism of both compounds is reasonably well described in terms of deformation of an 8/3/c2 sphere-packing model up to the pressures where the fluorine atoms become hexagonally close-packed. It is proposed that both compounds enter a phase with the fluorine atom arranged in a “super-dense” sphere packing at higher pressures. The zero pressure bulk modulus of FeF3 and GaF3 was determined as 12(2) and 37(3) GPa, respectively, and a scaling relation between the zero pressure bulk modulus and unit cell volumes was found for TiF3, CrF3, FeF3 and GaF3. 相似文献
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We present here the detailed results of X-ray diffraction from single quasicrystals of Al6CuLi3. X-ray precession photographs taken down the two-, three- and five-fold axes along with rotation and zero-level Weissenberg
photographs are shown. Preliminary analysis of the diffraction data rules out the twin hypothesis. 相似文献
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文章结合作者的科研工作,介绍了新的稀土金属间化合物及其晶体结构与标准X射线衍射数据的研究. 相似文献
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A. Jayarama M. R. Suresh Kumar S. M. Dharmaprakash R. Chitra R. R. Choudhury 《Pramana》2008,71(5):905-910
Thiourea-doped ammonium dihydrogen phosphate (TADP) exhibits nonlinear optical property and the second harmonic generation efficiency of these crystals is three times that of pure ammonium dihydrogen phosphate (ADP) crystal. In this context, the study of structural distortion in the thiourea-doped ADP crystal is significant, hence single neutron diffraction investigations were undertaken. The final R-factors are: R[F 2 > 2σ(F 2)] = 0.11, Goodness of fit(S) = 1.15. Though the dopant could not be located from the difference Fourier map, the cell parameters (a = b = 7.531(3) A, c = 7.544(5) Å) were found to be significantly greater than that of pure ADP at RT (a = b = 7.502(1) Å, c = 7.546(1) Å). This indicates that the dopant concentration in the crystals is small but enough to bring changes in the overall average structure. 相似文献
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We describe here a simple set-up for X-ray diffraction under high pressure using a diamond anvil cell employing a sealed tube. The set-up works in angular dispersive geometry and is built using rather common components that are available in a research laboratory. We show that using this set-up one can routinely acquire good-quality data for the determination of structural properties under pressure and the equations of state. Technical details are presented along with examples of experimental results for sodium chloride and LiV2O4. 相似文献
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We report the results of a natural phenacite from 0 to 30.9 GPa using in situ angle-dispersive X-ray diffraction and a diamond anvil cell at the National Synchrotron Light Source, Brookhaven National Laboratory. Over this pressure range, no phase change or disproportionation has been observed. The isothermal equation of state was determined. The values of V0, K0, and K0′ refined with a third-order Birch-Murnaghan equation of state are V0=1116.1±1.2 Å3, K0=223±9 GPa, and K0′=5.5±0.8. Furthermore, we confirm that the linear compressibilities (β) along a and c directions of phenacite are elastically isotropic (βa=1.50×10-3 and βc=1.34×10-3 GPa-1). Consequently, it can be concluded that the compressibility of phenacite under high pressures has been accurately constrained. 相似文献
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1310nm波段石英晶体旋光性的温度效应测试研究 总被引:1,自引:0,他引:1
为了测试温度对1310nm波段石英晶体旋光性的影响,采用高低温试验箱作为温控器,设计了双光路检测系统对石英晶体在1310nm波段旋光性的温度效应进行测试研究。实验结果表明,在-10~20℃温度范围内,对于确定波长的光,随温度的升高,石英晶体的旋光率增大;在25~50℃温度范围内,随温度的升高旋光率减小;对于同一温度,波长越长旋光率越小。根据测试结果求解Sellmeier方程得出了Sellmeier方程的常数与温度的关系式,从而可以得出任意温度下不同波长对应的石英晶体的旋光率。 相似文献