HIGH-PRESSURE PHASE TRANSFORMATIONS IN LABORATORY MECHANICAL MIXERS AND MORTARS
HIGH-PRESSURE PHASE TRANSFORMATIONS IN LABORATORY MECHANICAL MIXERS AND MORTARS
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DOI：
10.1038/186034a0
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发表时间：
1960-01-01
期刊：
影响因子：
64.8
通讯作者：
ROY, R
中科院分区：
文献类型：
--
作者：
DACHILLE, F;ROY, R
简单的实验室研磨机、迫击炮和类似设备的机械作用除了执行它们的主要物理功能外，有时还被用来协助化学反应。在这些化学反应中有相变。这种影响是由机械作用中的某种压力分量造成的，这一点可能看起来很明显，但压力的大小并不容易被认识到，也不能计算或测量。然而，在这个实验室研究二氧化铅(PbO2)高压多晶性的过程中，人们毫不奇怪地注意到，通过简单的研磨1形成了与新的高压多晶型相同的相，该相被证明只在10000巴以上的区域稳定。通过研磨少量(2克)，迅速证实了这一观察结果。常见的金红石型二氧化铅(I)在机械研钵和研钵相结合的实验室模式。在空气中研磨几个小时后，估计有三分之一转化为密度更高的正交晶型(II)。经过前期工作后发现，对于Burns和Bredig2报告的方解石通过在砂浆中研磨转变为文石的一些类似结果，原则上没有增加任何新的结果。高压相是由低压相形成的，其变化量与时间有关，随后的加热会形成低压相。一个显著的区别是，相平衡和热化学研究认为，方解石-文石在室温下的转变温度约为3,000巴，远低于氧化铅I-⇌-II转变所需的10,000巴。
THE mechanical action of simple laboratory grinders, mortars and similar devices has occasionally been used to assist in chemical reactions in addition to performing their primary physical functions. Among these chemical reactions are phase transformations. That the effect is due to some kind of a pressure component in the mechanical action may appear obvious, but the magnitude of the pressures is not readily appreciated, nor can it be calculated or measured. However, in the course of work in this laboratory on the high-pressure polymorphism of lead dioxide (PbO2), the information that a phase identical with the new high-pressure polymorph, which had been shown to be stable only in the region above 10,000 bars, had been formed by simple grinding1was noted with no little surprise. The observation was promptly confirmed by grinding a small amount (2 gm.) of the common rutile form (I) of lead dioxide in a mechanical mortar and pestle combination of laboratory pattern. Grinding in air for a few hours converted an estimated one-third to the denser orthorhombic form (II). After preliminary work, it transpired that nothing new in principle had been added to some similar results which had been reported by Burns and Bredig2on the transformation of calcite to aragonite by grinding in a mortar. The high-pressure phase was formed from the low-pressure one, the amount of change was dependent on time, and subsequent heating would form the low-pressure phase. A significant difference is that phase equilibrium and thermochemical studies3place the calcite–aragonite transformation at about 3,000 bars at room temperature, which is considerably lower than the 10,000 bars necessary for the lead oxide I ⇌ II transformation.