Amorphization from the quenched high-pressure phase

对几种半导体中具有β - sn结构的淬火高压相的非晶化进行了研究。采用构型坐标模型对结果进行分析。衍射峰强度的温度依赖性给出了相变前后两相间势垒*U的信息。采用同步辐射能量色散法对高压低温下的x射线衍射进行了测量。在90k时释放压力，对GaSb的高压相进行淬火。高压淬火相在温度低于1 GPa时表现为非晶化，在温度高于1 GPa时转变为ZnS相。当温度降至270 K以下时，也会出现类似的非晶化现象。在300 K时，随着压力的增加，AlSb在8 ~ 10 GPa时转变为β - sn相。随着压力的降低，高压相在4-2 GPa时恢复为ZnS相。另一方面，释放压力时，AlSb的高压相在100k处淬火。当温度升高至2.5 GPa和2.0 GPa时，淬火相出现非晶化现象。当温度升高到3.5 GPa时，在280k ~ 340k范围内，淬灭的高压相恢复为ZnS相。在240k和270k温度下，降低压力也可以观察到类似的非晶化现象，而在300k和330k温度下，可以观察到相变到ZnS相。构型坐标模型分析表明，*U对非晶相的压力导数远大于对ZnS相的压力导数。在3gpa时，不平等发生逆转。对于离子性较大的InAs和CdTe，只观察到向ZnS相的转变。成键性质的大离子性应使*U降低到ZnS相。因此，在较高的压力下，ZnS相的*U小于非晶相的*U，相变发生在ZnS相。

Amorphization from the quenched high-pressure phase with the beta-Sn structure has been studied for several semiconductors. Results were analyzed by using a configuration-coordinate model. The temperature dependence of the intensity of the diffraction peaks gives information concerning the potential barrier *U between the two phases of the before- and after-phase transitions.X-ray diffraction measurements at high pressures and low temperatures were carried out by an energy dispersive method using a synchrotron radiation.When pressure is released at 90 K, the high pressure phase of GaSb is quenched. The quenched high pressure phase shows amorphization when temperature is increased below 1 GPa, while it transforms to ZnS phase above 1 GPa. Similar amorphization occurs when temperature is decreased below 270 K.With increasing pressure at 300 K, AlSb transforms into the beta-Sn phase at 8-10 GPa. With decreasing pressure, the high pressure phase returns to the ZnS phase at 4-2 GPa. On the other hand, the high pressure phase of AlSb is quenched at 100 K when pressure is released. The quenched high pressure phase shows amorphization when temperature is increased at 2.5 GPa and 2.0 GPa. When temperature is elevated at 3.5 GPa, however, the quenched high pressure phase returns to the ZnS phase from 280 K to 340 K.Similar amorphization was also observed when pressure was reduced at 240 K and 270 K, while the phase transition to the ZnS phase was observed at 300 K and 330 K.Analysis from a configurational coordinate model proves that the pressure derivative of *U to the amorphous phase is much larger than that to the ZnS phase. Reverse of inequality occurs at 3 GPa.For InAs and CdTe with much larger ionicity, only the transition to the ZnS phase was observed. A large ionicity in the bonding nature should lower *U to the ZnS phase. Thus the phase transition to the ZnS phase occurs at higher pressure where *U to the ZnS phase is lower than *U to the amorphous phase.