The system NiAl2O4Ni2SiO4 at high pressures and temperatures: Spinelloids with spinel-related structures
The system NiAl2O4Ni2SiO4 at high pressures and temperatures: Spinelloids with spinel-related structures
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DOI：
10.1016/0022-4596(82)90372-3
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发表时间：
1982-09
影响因子：
3.3
通讯作者：
M. Akaogi;S. Akimoto;K. Horioka;Ken-ichi Takahashi;H. Horiuchi
中科院分区：
文献类型：
--
作者：
M. Akaogi;S. Akimoto;K. Horioka;Ken-ichi Takahashi;H. Horiuchi
研究了NiAl_2O_4--Ni_2SiO_4体系在压力为1.5∼~13.0 GPa时和温度为800∼~1450°C时的相关系，发现在压力高于4 Gpa的区域有两个新相：IV相和V相。V相在大约9.5 Gpa和1100°C的压力下不成比例地生成Ni2SiO4尖晶石、NiO和Al2O3的混合物。相III、IV和V在某些成分范围内形成固溶体：IV和V相的组成在NiAl2O4·Ni2SiO4附近，而III相从NiAl2O4·Ni2SiO4扩展到富NiAl2O4的一侧。所有的相I，∼，V在结构上都被认为是尖晶石的衍生物，“尖晶石”，具有三种四面体基团：孤立的四面体TO4，连接的一个T2O7和三个连接的一个T3O10。孤立四面体与连接四面体的比值在高压相中较大，在较低压力相中较小。III相与IV、V相成分范围的不同，可能是由于避免了O_3、、Al、、O、、Al、、O等四面体的连接。
Phase relations in the system NiAl2O4Ni2SiO4were studied in the pressure range 1.5 ∼ 13.0 GPa and in the temperature range 800 ∼ 1450°C. Two new phases, IV and V, were found in regions of pressure higher than 4 GPa. Phase V disproportionates into a mixture of Ni2SiO4-spinel, NiO, and Al2O3at approximately 9.5 GPa and 1100°C. Phases III, IV, and V form a solid solution in some compositional range: phases IV and V have a composition around NiAl2O4·Ni2SiO4, whereas phase III spreads from NiAl2O4·Ni2SiO4to the NiAl2O4-rich side. All the phases I ∼ V are structurally considered to be spinel derivatives, “spinelloids,” with three kinds of tetrahedral groups; isolated tetrahedraTO4, linked onesT2O7, and triply linked onesT3O10. The ratios of isolated tetrahedra to linked ones are large in the higher-pressure phases and small in the lower-pressure phases. The difference of compositional range of phase III from that of phases IV and V is possibly explained by the avoidance of linked tetrahedra such as O3AlOAlO3.