The low-temperature phase transition phenomena in Ba- and Pb-substituted La₂Mo₂O₉s have been investigated by means of thermal analysis, TEM observation and conductivity measurements. The low-temperature stable β′ phase appears even in Ba- and Pb-substituted La₂Mo₂O₉ by annealing the supercooled β-phase at around 400 °C as the case of Bi-substituted system. After annealing the samples at different temperatures and time, the observed endothermic heat at β′-β transition was fitted to Avrami's equation to discuss the kinetics of the transformation. From the activation energies of the obtained rate constant, it was found that β′-phase formation proceeds easier in Ba- and Pb-substituted La₂Mo₂O₉ rather than in Bi-substituted system. HR-TEM observation suggested the superstructure of β′-phase, and the thermal hysteresis in conductivity also supported the formation of β′-phase as detected by thermal analysis.

通过热分析，TEM观察和电导率测量研究了Ba和Pb取代的La ₂ Mo ₂ O ₉ s中的低温相变现象。甚至在Ba和Pb取代的La ₂ Mo ₂ O _9中也出现了低温稳定的β'相。对于双取代体系，可在400°C左右对过冷的β相进行退火处理。在不同的温度和时间对样品进行退火后，将观察到的在β'-β跃迁处的吸热热量与Avrami方程拟合，以讨论转化动力学。从所获得的速率常数的活化能，发现在Ba和Pb取代的La ₂ Mo ₂ O _9中，与在Bi取代体系中相比，β'相的形成更容易进行。HR-TEM观察表明β'相的上层结构，并且电导率的热滞现象也支持通过热分析检测到的β'相的形成。