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Radiation hardening studies of undoped NaCl and NaCl crystals doped with barium have been carried out both in the as-grown state and after quenching them from 650°C. It is observed that the radiation hardening is more in doped crystals and the results are explained taking into consideration the role of Z1-centres. 相似文献
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利用电注入着色装置,分别使用点阴极与平板阳极和点阳极与平板阴极在不同条件下对溴化钾晶体进行电注入着色.点阴极注入时,在着色晶体中产生V色心和F色心,计算得到F色心激活能0.84 eV.点阳极注入时,在着色晶体中产生V色心,计算得到V色心激活能0.49 eV.对着色晶体进行系统的光谱测量,确定色心光谱吸收带的光谱参数.对比两种情况下测得的电流~时间关系曲线,解释其色心形成机理. 相似文献
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The effect of quenching on microhardness and dislocation mobility of NaCl:Ca and NaCl:Pb single crystals was studied. Both the decrease and increase of these parameters in quenching occurred depending on the type and concentration of impurity and quenching temperature. The absence of correlation between the changes of microhardness and those of dislocation ensemble mobility which resulted from the quenching, has been found first. The conditions of the observation of this phenomenon were revealed and the interpretation of the experimental facts was proposed. 相似文献
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本文借助光子晶体中二能级原子的自发辐射理论说明缺陷态局域场存在的必然性以及局域场基本性质,为研究掺杂自发辐射的内在规律提供了理论依据,在此基础上,将自发辐射理论与数值模拟相结合,在缺陷介质中掺入和未掺入激活杂质时,数值模拟研究一维光子晶体的掺杂局域场特征以及受激辐射增强和透射率大于1现象与光子带隙边缘群速度异常和掺杂层复有效折射率负的虚部之间的内在规律,由此说明如在光子晶体的缺陷介质中掺入激活杂质,复有效折射率具有负的虚部,光子禁带中会出现品质因子非常高的杂质态,具有很大的态密度,这样便可实现自发辐射的增强,出现较强的受激辐射放大,在带隙的边缘处,光子晶体的群速度较小或群速度异常,受激辐射放大最容易出现在靠近光子带隙的边缘。 相似文献
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R. Poonguzhali R. Venkatesan T.M. Rajendiran P.S. Rao R.V.S.S.N. Ravikumar Y.P. Reddy 《Crystal Research and Technology》2000,35(10):1203-1207
Magnesium Potassium Phosphate Hexahydrate (MPPH), is analogous to the bio‐mineral struvite. Vanadyl doped MPPH crystals are grown by slow evaporation technique. EPR and optical absorption studies are carried out at room and liquid nitrogen temperatures. Spin‐Hamiltonian, crystal field and bonding parameters are evaluated. 相似文献
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用化学共沉淀法制备了 Y0.99-xBaxVO4:1; Dy3+荧光粉,研究了 Ba2+浓度(0≤x≤0.25)及电荷补偿剂 K+对荧光粉发光强度的影响.结果表明:在315 nm 紫外光激发下,随Ba2+浓度的增加,Y0.99-xBaxVO4:1;Dy3+荧光粉发光强度呈现先增加后降低的趋势,在x=0.1 处达最大值,与未添加 Ba2+的荧光粉相比发光强度提高约50;,但色坐标变化不明显,色温在5200 K 左右,为光色柔和的暖白光.电荷补偿剂 K+的添加使 Y0.99-xBaxVO4:1;Dy3+荧光粉在 Y0.99-x BaxKxVO4:1;Dy3+荧光粉发光强度的基础上明显提高,色坐标及色温变化不明显. 相似文献
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Vicker's microhardness study of (100), (010) and (001) faces of a non-linear optical crystal, L-arginine hydrobromide monohydrate (LAHBr)have been reported.(100) plane is found to be the weakest plane. It has been observed that the microhardness decreases with increasing load for the three crystal planes. The microhardness behaviour have been explained successfully with the help of the PSR model proposed by Li and Bradt. Work hardening index n for the three planes are found to be greater than 1.6 which indicates that LAHBr is a soft crystal. 相似文献
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P. Veeresham K. Narasimha Reddy U. V. Subba Rao V. Hari Babu 《Crystal Research and Technology》1983,18(11):1427-1431
Thermoluminescence studies of KBr crystals doped with 0.5 mole % of Ca2+ both in the ‘as-grown’ state and after quenching them from various elevated temperatures indicate that the position of the glow peak which has been assigned to F-centers is found to depend upon the state of dispersion of impurity. Bleaching of the X-irradiated samples result in an additional peak and this has been attributed to Z1-centers. Optical absorption measurements also confirm the formation of Z1-centers in Ca2+ doped KBr crystals. 相似文献
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Thermoluminescence studies of KCl crystals doped with 0.5 mole% of Manganese both in “as grown” state and after quenching them from various elevated temperatures indicate that the position of the glow peaks is found to depend upon the state of dispersion of impurity. In quenched crystals two additional peaks one around 130 and other around 215°C are observed. Dipoles near dislocations are suggested to be responsible for 130°C peak and 215°C peak to a complex formed by the associated of one or more Mn2+ ions with a single vacancy or an aggregate of vacancies, the complex being situation in the dislocation region. 相似文献
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A. Miyazaki H. Kimura X. Jia K. Shimamura T. Fukuda 《Crystal Research and Technology》1999,34(7):817-820
Small diameter crystals of Ba(B1-xAlx)2O4 were grown by Floating zone pulling down method and Micro-pulling down method to be compared with large diameter crystals grown by Czochralski method. While the Czochralski grown crystal was opaque, the crystal transparency was actually improved with the decrease of crystal diameter, i.e., the decrease of constitutional supercooling. The reason was the increase of temperature gradient caused by down-sizing of the crystal diameter deduced by down-sizing of the growth furnace. The adequate diameter for transparent crystal was determined depending on the Al content. 相似文献
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M. Suszyska 《Crystal Research and Technology》1974,9(10):1199-1207
Using the etch pit technique both the distribution and density of dislocations in undeformed and dynamically deformed nominally pure and Sr2+ or Pb2+ doped KCl crystals are examined. Additionally, the role of specimen geometry in the plastic deformation within the I deformation stage is determined. For all the crystals examined the relationship between screw dislocation density and plastic flow stress obeys the formula τ ⋍ ϱsc.1/2. 相似文献