The α—β transition in the cristobalite phases of SiO2 and AIPO4 I. X-ray studies
The α—β transition in the cristobalite phases of SiO2 and AIPO4 I. X-ray studies
复制标题
SiO2 和 AIPO4 方石英相的 α—β 转变 I. X 射线研究
DOI：
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发表时间：
1976
期刊：
影响因子：
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通讯作者：
A. Wright
中科院分区：
文献类型：
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作者：
A. Leadbetter;A. Wright
用X射线粉末衍射研究了SiO_2和AlPO_4方石英相的α-β转变。转变显示出明显的滞后，但也发生在约20°C的范围内，其中α和β相共存。的晶格参数显示出一个平滑和缓慢的变化与温度为每个阶段和相之间的离散的差异对应的体积差异约4%，显示的过渡是一阶的。对滞后现象进行了研究，得出结论：由于不同的微晶在不同的温度下发生相变，因此在块状样品中出现了相共存现象。结构方面的转变进行了讨论，它表明，相变涉及一个小的运动的原子周围的四倍螺旋轴连同无序的氧原子的位置
Abstract The α—β transition in the cristobalite phases of SiO2 and AlPO4 has been studied using X-ray powder diffraction. The transitions show marked hysteresis but also occur over a range of about 20°C in which the α and β phases coexist. The lattice parameters show a smooth and slow variation with temperature for each phase and a discrete difference between phases corresponding to volume differences of about 4%, showing that the transitions are of first order. The hysteresis has been studied and it is concluded that the phase coexistence in the bulk sample occurs because different crystallites undergo the transition at different temperatures. The structural aspects of the transformations are discussed and it is shown that the phase change involves a small movement of the atoms around four fold screw axes together with a disordering of oxygen atom positions