Raman studies of oxide minerals: a retrospective on cristobalite phases
Raman studies of oxide minerals: a retrospective on cristobalite phases
复制标题
氧化物矿物的拉曼研究：方石英相的回顾
DOI：
10.1088/0953-8984/19/27/275201
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
["Ming Zhang
中科院分区：
文献类型：
--
作者：
["Ming Zhang
简要回顾了氧化矿物的早期拉曼研究，强调了尚未建立模型的方面。在此基础上，还增加了大量未发表的α-和β-方石英SiO2和AlPO4的红外数据，这些数据遵循软模式，其阻尼从20 K下132 cm−1到略低于AlPO4 α- β转变温度的约80 cm−1，在SiO2中从155 cm−1到125 cm−1（转变是一级）。关于AlPO4和BPO4单晶（非粉末）的α-和β-方石英相存在相当好的数据，并根据最近关于β-方石英SiO2的争议进行了讨论。α -β方石石在AlPO4中的相变在冷却时使原始细胞的大小增加了一倍，可能是D2d到D2点群对称性的降低：β-AlPO4可能是（D2d12）与Z = 1的公式群，α-AlPO4可能是c2221 （D25）。对于AlPO4，我们的结果支持Liu et al （1993 Phys）的模型。Rev. Lett. 70 2750)超过了Swainson and Dove （1993 Phys.）。Rev. Lett. 71 3610)。在方石英SiO2中，点群对称性似乎是相同的，因此，先前提出的α-SiO2的四方空间群对称性为D44 (P41212)， β-SiO2的Oh7 （Fd3m）相只是慢时间平均，不能控制选择规则或电子带结构。
A brief review of early Raman studies of oxide minerals is given, emphasizing aspects yet to receive modelling. To these are added extensive unpublished infrared data on α- and β-cristobalite SiO2 and AlPO4, following a soft mode and its damping from 132 cm−1 at 20 K to about 80 cm−1 just below the AlPO4 α–β transition temperature and from 155 to 125 cm−1 in SiO2 (the transitions are of first order). Rather good data exist on the α- and β-cristobalite phases of AlPO4 and BPO4 single crystals (not powders) which are discussed in terms of the more recent controversy regarding β-cristobalite SiO2. The α–β cristobalite phase transition in AlPO4 doubles the primitive cell size on cooling, with a probable D2d to D2 point group symmetry reduction: β-AlPO4 is likely to be (D2d12) with Z = 1 formula group, and α-AlPO4 to be C 2221 (D25). For AlPO4 our results favour the model of Liu et al (1993 Phys. Rev. Lett. 70 2750) over that of Swainson and Dove (1993 Phys. Rev. Lett. 71 3610). The point group symmetries appear to be the same in cristobalite SiO2, so that the previously proposed tetragonal space group symmetry D44 (P41212) for α-SiO2 and the Oh7 (Fd3m) phase for β-SiO2 are only slow time averages that do not control selection rules or electronic band structures.