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Author Rawn, C. J. ♦ Makovec, D. ♦ Golic, L. ♦ Samardzija, Z. ♦ Kolar, D.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ CRYSTAL STRUCTURE ♦ BARIUM OXIDES ♦ CERIUM OXIDES ♦ TITANIUM OXIDES ♦ CRYSTAL GROWTH
Abstract A new structure located in the TiO{sub 2}-rich corner of the BaO-Ce{sub 2}O{sub 3}-TiO{sub 2} system crystallizes with an orthorhombic unit cell, space group Pnma, and with lattice parameters a = 27.88(1), b = 7.745(2), and c = 17.350(4) {angstrom}. Refinement on F resulted in R1 = 6.46% for 3,868 F{sub o} > 4{sigma}. The structure is made up of a network of corner-sharing TiO{sub 6} octahedra creating rhombic (perovskite-like) and pentagonal channels. In this new structure, there are eight unique rhombic positions (occupied chiefly by Ce atoms), four unique pentagonal positions (occupied chiefly by Ba atoms), and eight unique Ti positions. Full occupation of the sites would correspond to the formula Ba{sub 16}Ce{sub 32}Ti{sub 64}O{sub 192}; however, refinement of the site occupancies of the Ce and Ba atoms suggests some substitution of the cations and vacancies. Electron probe wavelength dispersive spectroscopic microanalysis averaged from twenty measurements on three crystals results in 4.68 {+-} 0.11 at% Ba, 9.63 {+-} 0.30 at% Ce, and 18.57 {+-} 0.35 at% Ti.
ISSN 00255408
Educational Use Research
Learning Resource Type Article
Publisher Date 1997-12-01
Publisher Place United States
Journal Materials Research Bulletin
Volume Number 32
Issue Number 12


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