...
  • 主题
高级搜索  >
历史搜索 清空历史
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 >Polyamorphic transitions in yttria-alumina liquids
【24h】

Polyamorphic transitions in yttria-alumina liquids

机译：氧化钇-氧化铝液体中的多晶过渡

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

There has been much recent discussion given to the phenomenon of polyamorphism where distinct, different states of amorphous liquids and solids are observed as a function of density. Underlying this phenomenon is the possibility of a first order liquid-liquid phase transition driven by the density and entropy differences between the two amorphous phases. Differential scanning calorimetry (DSC) of aluminate glasses containing 32-20 mol% Y2O3 has enabled characterisation of the thermodynamic differences between the high and low density amorphous phases. The DSC measurements show a glass transition temperature with onset at 1135 K. The width and the magnitude of jump in heat capacity at this glass transition indicates an extremely fragile liquid, that is there is a pronounced non-Arrhennian viscosity-temperature relation. There are two additional features of interest. A second glass transition at 1300 K is attributed to the low-density liquid (LDA) more stable at low temperature. This low-density liquid has a more Arrhenian viscosity temperature curve. A strong exothermic signal is seen between the two glass transitions and represents the transition between the supercooled, high-density liquid (HDA) and a low-density glass. Neutron scattering data suggest that the polyamorphic transition is accompanied by minor changes in the aluminate framework and more prominent changes in the local environment surrounding the yttrium ion, seen as an increase in the first neighbor yttrium-oxygen distance. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 47]
机译：对于多晶现象，最近有许多讨论，其中观察到非晶态液体和固体的不同，不同状态是密度的函数。这种现象的潜在原因是，由两个非晶相之间的密度和熵差驱动的一阶液相-液相转变是可能的。含有32-20 mol％Y2O3的铝酸盐玻璃的差示扫描量热法（DSC）能够表征高密度和低密度非晶相之间的热力学差异。 DSC测量显示玻璃化转变温度的起始温度为1135K。在此玻璃化转变温度下，热容的宽度和跃变幅度表示液体非常脆弱，即存在明显的非阿仑尼粘度-温度关系。有另外两个有趣的功能。 1300 K下的第二次玻璃化转变归因于在低温下更稳定的低密度液体（LDA）。这种低密度液体的阿仑尼粘度温度曲线更明显。在两个玻璃化转变之间可以看到一个强的放热信号，代表着过冷的高密度液体（HDA）和低密度玻璃之间的转变。中子散射数据表明，多晶态转变伴随着铝酸盐骨架的细微变化以及围绕钇离子的局部环境的更显着变化，这被认为是第一邻居钇-氧距离的增加。 （C）2001 Elsevier Science B.V.保留所有权利。 [参考：47]

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号