During thermal cycling, no obvious change of EM was observed but areversible change of EDP was, which is shown to correspond to reversible DO_3-M18R transformation.

• 在热循环中,衍衬像不发生明显改变,但观察到可逆的电子衍射图变化,分析表明这是可逆的DO_3?M18R型相变。