Niobate and Tantalate Pyrochlores: Soft Synthesis by the Fluoride Route

被引：13

作者：

Britvin, Sergey N. ^{[1
,2
]}

Siidra, Oleg I. ^{[2
]}

Lotnyk, Andriy ^{[3
]}

Krivovichev, Sergey V. ^{[2
]}

Depmeier, Wulf ^{[1
]}

机构：

[1] Univ Kiel, Inst Geowissensch, D-24118 Kiel, Germany

[2] St Petersburg State Univ, Geol Fac, Dept Crystallog, St Petersburg 199034, Russia

[3] Univ Kiel, Tech Fak, Inst Mat Wissensch, D-24143 Kiel, Germany

来源：

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY | 2010年 / 07期

关键词：

Niobium; Tantalum; Sol-gel processes; Nanostructures; Ion exchange; HYDROFLUORIC-ACID SOLUTIONS; ION-EXCHANGE PROPERTIES; MIXED-METAL OXIDES; HYDROTHERMAL SYNTHESIS; DEFECT PYROCHLORE; CRYSTAL-STRUCTURE; SOLID-STATE; NIOBIUM; COMPLEXES; NH4NBWO6;

D O I：

10.1002/ejic.200900999

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

A series of pyrochlores A(Nb,Ta)(2)(O,OH,F)(6)(nH(2)O), (A = NH(4), K, Rb, Cs) have been synthesized by hydrolysis of aqueous solutions of oxofluoroniobic (H(2)NbOF(5)) and fluorotantalic (H(2)TaF(7)) acids. This new method allows preparation of nanocrystalline niobate pyrochlores (crystal size 10-20 nm) by simple precipitation with subsequent boiling; tantalate analogues can be obtained by soft hydrothermal treatment. The synthesized compounds include new pyrochlores NH(4)Nb(2)O(5)(OH,F), NH(4)Ta(2)O(5)(OH,F)center dot nH(2)O and K(1-x)Nb(2)(O,OH)(5)F center dot nH(2)O as well as the already known CsNb(2)O(5)F, Rb(1-x)Nb(2)(O,OH)(5)F, CsTa(2)O(5)F and their hydroxyl analogues. Ion-exchange experiments revealed that K(0.7)Nb(2)(O,OH)(5)F center dot nH(2)O exhibits strong selective uptake of Pb(2+) from aqueous solutions, a feature not previously reported for pyrochlores. The facilitating role of fluoride ions in the synthesis of pyrochlores is discussed in comparison with zeolite synthesis, and the technological applicability of the new method is also presented in the paper.

引用

页码：1082 / 1088

页数：7

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