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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Dilatometric and positron annihilation lifetime spectroscopic studies on amorphous and polycrystalline selenium
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Dilatometric and positron annihilation lifetime spectroscopic studies on amorphous and polycrystalline selenium

机译：非晶态和多晶态硒的膨胀和正电子an没寿命谱研究

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Macroscopic expansion and microscopic positron annihilation behaviors on the three forms of selenium (Se): amorphous (a-Se), crystalline (c-Se) and partially crystalline (pc-Se) have been investigated over wide temperature ranges simultaneously by means of length dilatometry or positron annihilation lifetime spectroscopy, respectively. No positronium formation is detected in two morphological forms (a-Se) and (pc-Se). Dilatometric and PALS responses on the a-Se and pc-Se samples exhibit behavior characterized by the presence of more or less pronounced bend effects at the characteristic transition temperatures T-g(a-Se) and T-x(pc-Se) in contrast to the crystalline form without any bend effect. The positron lifetimes for a-Se are systematically lower than those for pc-Se. PALS experiments show that the annihilation of positron is sensitive to the glass transition similarly to ortho-positronium. The thermal expansion coefficients of the macroscopic length and approximately, of the macroscopic volume and that of the positron lifetime in both a-Se and pc-Se have been determined and compared. In a-Se, the respective thermal expansion coefficients of positron lifetime in both the physical states are approximately two-fold higher than the estimated volumetric ones of amorphous Se and in pc-Se even about five-fold larger in both the temperature regions below and above the transition temperature T-x comparable with the glass transition of a-Se. All these findings lead to the physical picture of pc-Se sample as non-perfect crystalline matrix having the disordered regions between microcrystals similar to a-Se but with distinct electron density and expansion characteristics. (c) 2005 Published by Elsevier B.V.
机译：三种类型的硒（Se）的宏观膨胀和微观正电子an灭行为已在很宽的温度范围内同时通过长度研究了无定形（a-Se），晶体（c-Se）和部分晶体（pc-Se）膨胀计或正电子an没寿命谱。没有检测到两种形态（a-Se）和（pc-Se）的正电子形成。与晶体相反，a-Se和pc-Se样品的膨胀和PALS响应表现出特征在于在特征转变温度Tg（a-Se）和Tx（pc-Se）处或多或少明显的弯曲效应形式没有任何弯曲效果。 a-Se的正电子寿命系统地低于pc-Se的正电子寿命。 PALS实验表明，正电子an灭对玻璃化转变的敏感性与正电子相似。已经确定并比较了a-Se和pc-Se中的宏观长度的热膨胀系数和大约宏观的体积的热膨胀系数以及正电子寿命的热膨胀系数。在a-Se中，两种物理状态下正电子寿命的热膨胀系数分别约为非晶态Se的体积估计值的两倍，而在pc-Se中，在低于和低于这两个温度区域中，正电子寿命的热膨胀系数都大约高出五倍。高于转变温度Tx，与α-Se的玻璃化转变相当。所有这些发现导致pc-Se样品的物理图片为非完美的晶体基质，在微晶之间具有类似于a-Se的无序区域，但具有明显的电子密度和膨胀特性。 （c）2005年由Elsevier B.V.

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