Solid-state synthesis in the system Na{sub 0.8}Nb{sub y}W{sub 1-y}O{sub 3} with 0{<=}y{<=}0.4: A new phase, Na{sub 0.5}NbO{sub 2.75}, with perovskite-type structure

Journal Article · Tue Apr 15 04:00:00 EDT 2008 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2008.01.027· OSTI ID:21128247

Debnath, Tapas ^[1]; Ruescher, Claus H; Gesing, Thorsten M; Koepke, Juergen ^[1]; Hussain, Altaf ^[2]

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1. Institute of Mineralogy, Leibniz Universitaet Hannover, D-30167 Hannover (Germany)
2. Department of Chemistry, University of Dhaka (Bangladesh)

Series of compounds in the system Na{sub x}Nb{sub y}W{sub 1-y}O{sub 3} were prepared according to the appropriate molar ratio of Na{sub 2}WO{sub 4}, WO{sub 3}, WO{sub 2} and Nb{sub 2}O{sub 5} with x=0.80 and 0.0{<=}y{<=}0.4 at 600 deg. C in evacuated silica glass tubes. These compounds were investigated by X-ray powder diffraction, optical microscopy, microprobe analysis, Raman and optical microspectroscopy. A y-dependent separation into three distinct coloured crystallites with cubic perovskite-type structures is observed: (i) red-orange crystallites with composition Na{sub x}WO{sub 3} with slightly decreasing x (i.e. 0.8-0.72) with increasing nominal y, (ii) bluish solid solution of composition Na{sub x}Nb{sub y}W{sub 1-y}O{sub 3} and (iii) white crystallites of a new phase having defect perovskite-type structure with composition Na{sub 0.5}NbO{sub 2.75}. - Graphical abstract: Optical micrograph of a polished sample of nominal composition Na{sub 0.8}Nb{sub 0.4}W{sub 0.6}O{sub 3} showing a mixture of three different coloured crystals: red, light blue and white. The scale bar is 30 {mu}m.

• OSTI ID: 21128247
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 4 Vol. 181; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CRYSTAL DEFECTS
CRYSTALS
NIOBATES
NIOBIUM OXIDES
OPTICAL MICROSCOPY
PEROVSKITE
SILICA
SODIUM TUNGSTATES
SOLID SOLUTIONS
SYNTHESIS
TUNGSTEN BRONZE
TUNGSTEN OXIDES
X-RAY DIFFRACTION