A two-step ion exchange route to the new metastable double-layered perovskite, (Rb,Na)1-xCax/2LaNb2O7 (x ≈ 0.9)

被引：18

作者：

Cushing, BL

Wiley, JB ^{[1
]}

机构：

[1] Univ New Orleans, Dept Chem, New Orleans, LA 70148 USA

[2] Univ New Orleans, Adv Mat Res Inst, New Orleans, LA 70148 USA

来源：

MATERIALS RESEARCH BULLETIN | 1999年 / 34卷 / 02期

关键词：

layered compounds; oxides; chemical synthesis; differential scanning calorimetry (DSC); X-ray diffraction;

D O I：

10.1016/S0025-5408(99)00009-4

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

A new metastable double-layered perovskite, Rb0.04Na0.08Ca0.44LaNb2O7, has been synthesized by a two-step ion exchange route. Initially, RbLaNb2O7 is reacted to produce the known metastable phase NaLaNb2O7; then this is exchanged with calcium to yield the title compound. The product has neither the RbLaNb2O7 nor NaLaNb2O7 structure types, but converts to a superstructure of KLaNb2O7 with an orthorhombic unit cell: a = 3.885(1), b = 7.725(2), and c = 20.884(4) Angstrom. Direct calcium exchange of RbLaNb2O7 results in poorly crystalline products with only 31% exchange, while exchange with KLaNb2O7 shows little evidence of reaction. The importance of size matching in divalent-for-monovalent cation exchange is discussed. (C) 1999 Elsevier Science Ltd.

引用

页码：271 / 278

页数：8

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[21] REVISED EFFECTIVE IONIC-RADII AND SYSTEMATIC STUDIES OF INTERATOMIC DISTANCES IN HALIDES AND CHALCOGENIDES [J].