排序方式: 共有73条查询结果,搜索用时 15 毫秒
1.
Xiaodong Xu Pingxin Song Guoqing Zhou Jun Xu Peizhen Deng 《Solid State Communications》2004,129(11):717-720
Cr4+:YbAG (Cr4+:Yb3Al5O12) crystal with a size up to Φ24 mm×30 mm was grown by the Czochralski method. In the absorption spectrum, there are two absorption bands at 939 and 969 nm, respectively, which are suitable for InGaAs diode laser pumping, and there is an absorption band at 1030 nm, which is suitable for passive Q-switched laser output at 1.03 μm. A broad emission spectrum from 970 to 1100 nm was exhibited from 940 nm wavelength pumping. This crystal is promising as a self-Q-switched laser crystal used for compact, efficient, highly stable, passive self-Q-switched thin chip solid-state lasers. 相似文献
2.
D. Shulyatev N. Kozlovskaya A. Pestun Ya. Mukovskii L. Elochina R. Zainullina 《Journal of Crystal Growth》2009,311(16):4142-4145
Single crystals of La0.75Y0.05Sr0.2 MnO3 have been grown by the floating zone technique. The yttrium distribution in the radial and axial directions in the crystals was studied for different growth rates. The sample grown at high rate showed inhomogeneity in the yttrium content in the growth direction, while the sample grown at relatively low rate was homogeneous in the growth direction, but demonstrated compositional separation between the Y-poor central part and Y-enriched peripheral part in the perpendicular plane. The compositional separation led to magnetic inhomogeneity. 相似文献
3.
Amale Nezzal Luc Aerts Marleen Verspaille Geert Henderickx Andreas Redl 《Journal of Crystal Growth》2009,311(15):3863-3870
The polymorphism of sorbitol was investigated, confirming the existence of four anhydrous crystalline phases plus the hydrate. The crystallised melt (CM), the alpha form, and the gamma form were obtained via a dry route. The CM was confirmed to be a crystalline state with a spherulite morphology. The alpha form was obtained via direct conversion from the CM, in contrast to more complicated routes previously reported, and was found to have a very high crystallinity. Gamma crystals were obtained by seeding the melt at high temperature; however, crystallinity was clearly less than for alpha crystals. 相似文献
4.
Based on dislocation theory, we investigate the mechanism of strain rate effect. Strain rate effect and dislocation motion are bridged by Orowan's relationship, and the stress dependence of dislocation velocity is considered as the dynamics relationship of dislocation motion. The mechanism of strain rate effect is then investigated qualitatively by using these two relationships although the kinematics relationship of dislocation motion is absent due to complicated styles of dislocation motion. The process of strain rate effect is interpreted and some details of strain rate effect are adequately discussed. The present analyses agree with the existing experimental results. Based on the analyses, we propose that strain rate criteria rather than stress criteria should be satisfied when a metal is fully yielded at a given strain rate. 相似文献
5.
The rapid dendritic growth of primary Ni3Sn phase in undercooled Ni-30.9%Sn-5%Ge alloy is investigated by using the glass fluxing technique. The dendritic growth velocity of Ni3Sn compound is measured as a function of undercooling, and a velocity of 2.47m/s is achieved at the maximum undercooling of 251 K (0.17TL). The addition of the Ge element reduces its growth velocity as compared with the binary Ni75Sn25 alloy. During rapid solidification, the Ni3Sn compound behaves like a normal solid solution and it displays a morphological transition of "coarse dendrite-equiaxed grain-vermicular structure" with the increase of undereooling. Significant solute trapping of Ge atoms occurs in the whole undercooling range. 相似文献
6.
A new sample component is presented for the Monte Carlo, ray-tracing program, McStas, which is widely used to simulate neutron scattering instruments. The new component allows the sample to be described by its material dynamic structure factor, which is separated into coherent and incoherent contributions. The effects of absorption and multiple scattering are treated and results from simulations and previous experiments are compared. 相似文献
7.
Dunhua Cao Guangjun Zhao Jianyu Chen Qin Dong Jiang Zhu Hongjun Li 《Journal of luminescence》2009,129(10):1169-1173
RE, Mn:YAP (RE=Yb and Ce) crystals with dimension of Φ 25×60 mm were successfully grown by the Czochralski method. The spectroscopic properties of RE, Mn:YAP (RE=Yb and Ce) crystals before and after γ-irradiation were investigated at room temperature. The results show that the content of Mn4+ ions was increased with the Yb3+ ions co-doping, but decreased by Ce3+ ions co-doping. Thermoluminescence (TL) spectra of the crystals indicate three steps of recombination, and the probable recombination processes were discussed. 相似文献
8.
M. Matuchova K. Zdansky J. Zavadil A. Danilewsky F. Riesz M.A.S. Hassan D. Alexiew R. Kral 《Journal of Crystal Growth》2009,311(14):3557-3562
Lead iodide (PbI2) shows excellent electronic properties for detection of ionizing radiation. We report the introduction of rare-earth elements and other elements as admixtures during synthesis to study their influence on the quality of single crystals. Synthesized material as well as single crystals have been characterized by measurements of electrical resistivity and low-temperature photo luminescence and index of refraction. The structural quality with respect to polytypes was analysed by electron back scatter diffraction. Makyoh topography was applied for surface studies. 相似文献
9.
A. Maljuk V. Tsurkan V. Zestrea O. Zaharko A. Cervellino A. Loidl D.N. Argyriou 《Journal of Crystal Growth》2009,311(16):3997-4000
We report the first successful floating-zone growth of high-quality CoAl2O4 single crystals with volume up to 1 cm3 free from inclusions and sub-grains. The neutron rocking curves of the CoAl2O4 crystal have the width of about 0.30 degree proving the excellent quality of the grown samples. X-ray synchrotron experiments show that crystals have spinel structure with the lattice constant a0=8.09853(1) Å. Magnetization measurements give the effective magnetic moment μeff=4.63 μB per Co+2 ion in a good agreement with previous measurements on ceramic samples. 相似文献
10.
In this work, Ce:YAG crystal with the size of ?4 in was successfully grown by the TGT method. The optical and scintillation properties of as-grown Ce:YAG crystals were investigated. Three obvious absorption bands at 223, 340 and 460 nm and two weak color-center absorption bands at 296 and 370 nm are observed in as-grown Ce:YAG crystal. Fluorescence with an emission peak at 398 nm is observed due to the color centers, and absorption bands of the color centers can be eliminated by annealing in O2 or H2 atmosphere at 1673 K for 24 h. Yellow-green fluorescence centered at 530 nm is found when the crystal was excited at 460 nm and the 530 nm excitation spectrum shows two peaks at 340 and 460 nm. X-ray fluorescence spectrum of as-grown crystal shows three emission peaks at 300, 360 and 530 nm. An average light output of 1360 phe/MeV and a single exponential decay with the decay time constant of 62.97 ns are found in as-grown Ce:YAG crystal. 相似文献