Low-temperature phase of sodium priderite, Na{sub x}Cr{sub x}Ti{sub 8{minus}x}O{sub 16}, with a monoclinic hollandite structure

Journal Article · Tue Jun 01 04:00:00 EDT 1999 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1999.8239· OSTI ID:679228

Michiue, Yuichi; Sato, Akira; Watanabe, Mamoru ^[1]

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1. National Inst. for Research in Inorganic Materials, Tsukuba, Ibaraki (Japan)

Sodium priderite, Na{sub x}Cr{sub x}Ti{sub 8{minus}x}O{sub 16} (x {approx} 1.7) having a tetragonal hollandite structure, undergoes monoclinic distortion below ca. 273 K. The monoclinic phase structure, the space group 12/m, and cell parameters a = 10.108(7), b = 2.9526(4), and c = 9.975(7) {angstrom}, and {beta} = 90.06(4){degree} with Z = 1, were refined using data measured at 223 K through single-crystal X-ray diffraction (R = 5.1 wR = 5.7%). Electron density maps drawn using the maximum entropy method clearly show variations in asymmetry in the Na ion distribution in the tunnel associated with monoclinic deformation of the framework. A marked difference between the monoclinic and tetragonal structures is the inequality of Na occupation ratios among the four positions in a cavity. 13 refs., 4 figs., 3 tabs.

• OSTI ID: 679228
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 145; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM OXIDES
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
EXPERIMENTAL DATA
LATTICE PARAMETERS
SODIUM OXIDES
TEMPERATURE DEPENDENCE
TITANIUM OXIDES
X-RAY DIFFRACTION