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>The features of structure and isomorphic substitutions in flux-synthesized V-containing beryls and V-containing beryllian indialite
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The features of structure and isomorphic substitutions in flux-synthesized V-containing beryls and V-containing beryllian indialite
An X-ray diffraction study of isostructural V-containing beryl (V-Iz) and V-containing beryllian indialite (V-BI) (the general formula M VI _2T2 IV _3T1 IV _6O _(18))1 synthesized in the Al _2Be _3Si _6O _918)-Mg,Ca/F,Cl flux system with V _2O _5 impurity has been performed. It is shown for V-Iz that the isomorphic replacement of some part of Al ~(3+) in the octahedron with larger V ~(3+) and Mg ~(2+) cations and a small fraction of Be ~(2+) ions with Al ~(3+) in the interring tetrahedron T2, as well as the introduction of alkaline ions into R voids, leads to an increase in the average bonds lengths in the M position and increases the unit-cell parameter a at an insignificant increase in the parameter c. In V-Bi, the heterovalent replacement of some part of Mg ~(2+) ions by V ~(3+) ions, with complex isomorphism in all structural positions, is accompanied by the isovalent Mg ~(2+). Fe ~(2+) scheme. These substitutions cause some decrease in the parameter c of V-Bi with the preservation of its parameter a. It is found that T1 tetrahedra in V-BI are much closer to ideal than in V-Iz, T2 tetrahedra are distorted much more weakly, and M octahedra are distorted somewhat more strongly. However, the degree of distortion of the ring tetrahedron T1 in V-BI reaches 0.9 rel. %. This fact indicates that V-BI and Cr-BI have a similar dispo- sition to congruent melting, which significantly inferior that of "pure" species.
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机译：在Al _2Be中合成的具有同构结构的含V的绿柱石（V-Iz）和含V的铍辉石（V-BI）（通式M VI _2T2 IV _3T1 IV _6O _（18））1的X射线衍射研究_3Si _6O _918）-具有V _2O _5杂质的Mg，Ca / F，Cl助熔剂系统已执行。对于V-Iz表明，八面体中的Al〜（3+）的某些部分被较大的V〜（3+）和Mg〜（2+）阳离子和一小部分Be〜（2+ ）在四面体T2内具有Al〜（3+）的离子，以及将碱性离子引入R空隙中，会导致M位置的平均键长增加，并在a处增加晶胞参数a参数c的增加很小。在V-Bi中，Mg〜（2+）的某些部分被V〜（3+）离子异价取代，在所有结构位置均具有复杂的同构性，同时伴有等价的Mg〜（2+）。 Fe〜（2+）方案。这些替换导致V-Bi的参数c有所降低，同时保留了其参数a。发现V-BI中的T1四面体比V-1z更接近理想，T2四面体更弱地变形，而M八面体更强地变形。但是，V-BI中的环四面体T1的变形度达到0.9 rel。 ％。这一事实表明，V-BI和Cr-BI与全熔具有相似的分布，这大大低于“纯”物质。
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