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Title: Novel metal oxides prepared by ingenious synthetic routes

Abstract

Several novel oxides have been prepared by the decomposition of carbonate precursors of calcite structure of the general formulas Mn/sub 1-x/M/sub x/CO/sub 3/ (M = Mg,Co,Cd), Ca/sub 1-x/M/sup prime//sub x/CO/sub 3/, and Ca/sub 1-x/-yM/sup //sub x/M/sup double-prime//sub y/CO/sub 3/ (M',M'' = Mn,Fe,Co). Typical of the oxides synthesized are a variety of monoxides, Mn/sub 1-x/M/sub x/O, of rocksalt structure and perovskite-related oxides such as Ca/sub 2/FeCoO/sub 5/, Ca/sub 2/Co/sub 2/O/sub 5/, and Ca/sub 3/Fe/sub 2/MnO/sub 8/, many of them exhibiting novel anion-vacancy-ordered superstructures. An interesting series of oxides prepared by the topotactic reduction of Ca/sub 2/Fe/sub 2-x/Mn/sub x/O/sub 6-y/ (synthesized by the decomposition of the corresponding carbonate precursors) is Ca/sub 2/Fe/sub 2-x/Mn/sub x/O/sub 5/ where three different coordination polyhedra (octahedra, tetrahedra, and square pyramids) of the transition metals coexist. Topotactic reduction of LaCoO/sub 3/ and LaNiO/sub 3/ yields new oxides, La/sub 2/Co/sub 2/O/sub 5/ and La/sub 2/Ni/sub 2/O/sub 5/, possessing anion-vacancy-ordered superstructures. While La/sub 2/Co/sub 2/O/sub 5/ adopts the brownmillerite structure, La/sub 2/Ni/sub 2/O/sub 5/ exhibits a new type of vacancy ordering with octahedral and square-planar coordination of Ni/sup 2 +/. Slightly reduced LaNiO/sub 3/ seem to exhibit crystallographic shear (CS) planes similar to WO/sub 3-x/. Topotactic dehydration of isostructural Mo/submore » 1-x/W/sub x/O/sub 3/ x H/sub 2/O provides a convenient route for the synthesis of Mo/sub 1-x/W/sub x/O/sub 3/ (0< or =x< or =1) in ReO/sub 3/-related structure.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, India
OSTI Identifier:
5940157
Resource Type:
Journal Article
Journal Name:
J. Mat. Res.; (United States)
Additional Journal Information:
Journal Volume: 1:2
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CADMIUM OXIDES; SYNTHESIS; CALCIUM OXIDES; COBALT OXIDES; IRON OXIDES; LANTHANUM OXIDES; MAGNESIUM OXIDES; MANGANESE OXIDES; MOLYBDENUM OXIDES; TUNGSTEN OXIDES; CRYSTAL STRUCTURE; DEPOSITION; HYDRATES; SOLID SOLUTIONS; ALKALINE EARTH METAL COMPOUNDS; CADMIUM COMPOUNDS; CALCIUM COMPOUNDS; CHALCOGENIDES; COBALT COMPOUNDS; DISPERSIONS; IRON COMPOUNDS; LANTHANUM COMPOUNDS; MAGNESIUM COMPOUNDS; MANGANESE COMPOUNDS; MIXTURES; MOLYBDENUM COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; RARE EARTH COMPOUNDS; REFRACTORY METAL COMPOUNDS; SOLUTIONS; TRANSITION ELEMENT COMPOUNDS; TUNGSTEN COMPOUNDS; 360201* - Ceramics, Cermets, & Refractories- Preparation & Fabrication

Citation Formats

Rao, C.N.R., Gopalakrishnan, J., Vidyasagar, K., Ganguli, A.K., Ramanan, A., and Ganapathi, L. Novel metal oxides prepared by ingenious synthetic routes. United States: N. p., 1986. Web. doi:10.1557/JMR.1986.0280.
Rao, C.N.R., Gopalakrishnan, J., Vidyasagar, K., Ganguli, A.K., Ramanan, A., & Ganapathi, L. Novel metal oxides prepared by ingenious synthetic routes. United States. doi:10.1557/JMR.1986.0280.
Rao, C.N.R., Gopalakrishnan, J., Vidyasagar, K., Ganguli, A.K., Ramanan, A., and Ganapathi, L. Sat . "Novel metal oxides prepared by ingenious synthetic routes". United States. doi:10.1557/JMR.1986.0280.
@article{osti_5940157,
title = {Novel metal oxides prepared by ingenious synthetic routes},
author = {Rao, C.N.R. and Gopalakrishnan, J. and Vidyasagar, K. and Ganguli, A.K. and Ramanan, A. and Ganapathi, L.},
abstractNote = {Several novel oxides have been prepared by the decomposition of carbonate precursors of calcite structure of the general formulas Mn/sub 1-x/M/sub x/CO/sub 3/ (M = Mg,Co,Cd), Ca/sub 1-x/M/sup prime//sub x/CO/sub 3/, and Ca/sub 1-x/-yM/sup //sub x/M/sup double-prime//sub y/CO/sub 3/ (M',M'' = Mn,Fe,Co). Typical of the oxides synthesized are a variety of monoxides, Mn/sub 1-x/M/sub x/O, of rocksalt structure and perovskite-related oxides such as Ca/sub 2/FeCoO/sub 5/, Ca/sub 2/Co/sub 2/O/sub 5/, and Ca/sub 3/Fe/sub 2/MnO/sub 8/, many of them exhibiting novel anion-vacancy-ordered superstructures. An interesting series of oxides prepared by the topotactic reduction of Ca/sub 2/Fe/sub 2-x/Mn/sub x/O/sub 6-y/ (synthesized by the decomposition of the corresponding carbonate precursors) is Ca/sub 2/Fe/sub 2-x/Mn/sub x/O/sub 5/ where three different coordination polyhedra (octahedra, tetrahedra, and square pyramids) of the transition metals coexist. Topotactic reduction of LaCoO/sub 3/ and LaNiO/sub 3/ yields new oxides, La/sub 2/Co/sub 2/O/sub 5/ and La/sub 2/Ni/sub 2/O/sub 5/, possessing anion-vacancy-ordered superstructures. While La/sub 2/Co/sub 2/O/sub 5/ adopts the brownmillerite structure, La/sub 2/Ni/sub 2/O/sub 5/ exhibits a new type of vacancy ordering with octahedral and square-planar coordination of Ni/sup 2 +/. Slightly reduced LaNiO/sub 3/ seem to exhibit crystallographic shear (CS) planes similar to WO/sub 3-x/. Topotactic dehydration of isostructural Mo/sub 1-x/W/sub x/O/sub 3/ x H/sub 2/O provides a convenient route for the synthesis of Mo/sub 1-x/W/sub x/O/sub 3/ (0< or =x< or =1) in ReO/sub 3/-related structure.},
doi = {10.1557/JMR.1986.0280},
journal = {J. Mat. Res.; (United States)},
number = ,
volume = 1:2,
place = {United States},
year = {1986},
month = {3}
}