TRANSFORMATION OF 3-CONNECTED SILICON IN BASI2
TRANSFORMATION OF 3-CONNECTED SILICON IN BASI2
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DOI：
10.1016/0022-4596(80)90270-4
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发表时间：
1980-01-01
影响因子：
3.3
通讯作者：
EVERS, J
中科院分区：
文献类型：
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作者：
EVERS, J
用x射线粉末技术研究了三晶basi2在高达40 kbar和1000℃的淬火条件下的固-固转变。在高压-高温条件下，具有孤立硅四面体的正交型BaSi2I、具有波纹硅层的三角形BaSi2II和具有三维三连接硅网的立方型BaSi2III之间的所有转换都可以在大约5分钟内完成。在环境条件下，BaSI2I和BaSi2III的摩尔体积差异较大（ΔVI-III =−6.79 cm3/mol），而BaSi2III和BaSi2II的摩尔体积差异很小（ΔVIII-II=−0.05 cm3/mol）。因此，在压力-温度相图中，边界（I-III）表现出强烈的压力依赖性，而（III-II）对压力变化的依赖性较小。三种固相之间的三相点在11kbar和925℃附近。二价金属和四价类金属的取代容易影响BaSi2的相关系。
Solid-solid transitions in trimorphic BaSi2have been investigated up to 40 kbar and 1000°C by X-ray powder technique in quenched samples. All transformations between orthorhombic BaSi2I with isolated Si-tetrahedra, trigonal BaSi2II with corrugated Si-layers, and cubic BaSi2III with a three-dimensional three-connected Si-net can be performed in approximately 5 min at high-pressure-high-temperature conditions. At ambient conditions the difference in molar volume between BaSI2I and BaSi2III is relatively large (ΔVI–III= −6.79 cm3/mole) and that between BaSi2III and BaSi2II very small (ΔVIII-II= −0.05 cm3/mole). Consequently in the pressure-temperature phase diagram the boundary (I–III) shows a strong pressure dependence contrary to that of (III-II) which is less dependent on variation of pressure. The triple point between the three solid phases is near 11 kbar and 925°C. Substitution of divalent metal and quadrivalent metalloid can easily influence the phase relations in BaSi2.