【摘要】 笔者利用透射电子显微镜（TEM）和加热台等技术,对河北承德黑山P2₁ca顽辉石的相变过程进行动态观察,证实了P2₁ca斜方辉石是Pbca斜方辉石的同质多象低温变体。相变温度在800～900℃之间。这一变相是通过P2₁ca斜方辉石晶体结构中四分之一呈S旋转的Si—O四面体链改变为O旋转类型而实现的。更多还原

【Abstract】 Using transmission electron microscope and heating stage techniques, the authors have studied the phase transition of P2₁ca enstatite (En₅₆Fs₄₁Wo₃). When the sample is heated to 900℃ or so, the diffraction spots of k≠2n in Okl diffraction of P2₁ca enstatite disappear, forming orthopyroxene with Pbca symmetry. The phase transition from P2₁ca orthopyroxene to Pbca orthopyroxene is achieved through the change in the rotation type of Si-O tetrahedra chain which is Srotation in the structure of P2₁ca orthopyroxene. This phase transition experiment demonstrates that P2₁ca orthopyroxene is the low-temperature polymorph of Pbca orthopyroxene.更多还原