Stability, thermal behavior and crystal structure of ion ordered Bi{sub 1-x}Ln{sub x}O{sub 1.5} phases (Ln = Sm-Dy)
Journal Article
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· Journal of Solid State Chemistry
- Ecole Nationale Superieure de Chimie de Lille and Universite des Sciences et Technologies de Lille, Villeneuve (France)
- National Institute for Research in Inorganic Materials, Ibaraki (Japan)
This paper deals with the bcc Bi{sub 1-x}Ln{sub x}O{sub 1.5} phases recently isolated in the composition range 0.275 {le} x {le} 0.40 depending on the lanthanide substituent (Ln = Sm, Eu, Gd, Tb, Dy). These phases are slowly obtained by long time annealing ({approx_equal} 1500 hr) of the corresponding fcc {delta}-Bi{sub 3}O{sub 3} type phase at about 800{degrees}C, and exhibit a cell parameter almost twice the fcc parameter. X-ray diffraction investigations of the stability and crystal structure properties of the phases during thermal treatments have clearly shown that they are stable only in the temperature range 800-1000{degrees}C, depending on the lanthanide substituent. Below 800{degrees}C, they are metastable, but an annealing treatment or a slow dynamic thermal treatment between 600 and 800{degrees}C leads to a partial transformation into the true low temperature stable phases of the systems. Above 1000{degrees}C the fast transformation bcc to fcc {delta}-Bi{sub 2}O{sub 3} type occurs systematically. The crystal structure of bcc Bi{sub 0.65}Gd{sub 0.35}O{sub 1.5} has been refined with a= 11.0488(1) {Angstrom}, 12{sub 1}3 space group (Z = 32), using the Rietveld method. Starting from a {delta}-Bi{sub 2}O{sub 3} type phase, the formation of this bcc phase can be explained on the basis of a structural disorder-order transformation as a result of a long time annealing process at high temperature.
- OSTI ID:
- 518426
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 129; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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