热膨胀法原位观测SrCoO_(3-δ)材料的一级相变

In-situ observation of first-order phase transition in SrCoO_(3-δ) by thermal expansion method

在相变点处,若两相化学势的一阶导数不连续则为一级相变.材料发生一级相变时,必定伴随着体积的变化.用热膨胀方法原位观测了SrCoO_(3-δ)材料的一级相变过程.结果表明:SrCoO_(3-δ)材料在920℃时出现体积突变现象,对应六角相到立方相的转变.原位观测结果也进一步确认了多晶材料可通过测量其线膨胀来反映其体膨胀变化规律.

For a first order phase transition,the first derivative in the chemical potential of the two phases is discontinuity.The first order phase transition of a material must be accompanied by a change in volume.The process of first order phase transition in SrCoO_(3-δ) material was observed by thermal expansion method.The experiment results showed that a markedly abrupt change in volume was observed at around 920℃for the SrCoO_(3-δ),which corresponding to the phase transition from the hexagonal phase to the cubic phase.The results of in-situ observation further confirmed that the change law of volume expansion of polycrystalline materials could be reflected by measuring the linear expansion.