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Crystal structure and electrical properties of Ca {sub x}WO{sub 3} (0.01 {<=} x {<=} 0.15) prepared by hybrid microwave synthesis

Journal Article · · Materials Research Bulletin
OSTI ID:20891650
 [1];  [1];  [1];  [1];  [1]
  1. National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, P. O. Box 603, Beijing 100080 (China)
Calcium tungsten bronzes Ca {sub x}WO{sub 3} (0.01 {<=} x {<=} 0.15) were synthesized by hybrid microwave method from mixtures of CaO, WO{sub 3} and tungsten powder. Single-phased samples can be obtained by microwave heating within 40 min. With the increase of calcium content, the crystal structure of Ca {sub x}WO{sub 3} transforms from orthorhombic (0.01 {<=} x {<=} 0.02) to tetragonal (0.03 {<=} x {<=} 0.11) and then to cubic (0.12 {<=} x {<=} 0.15). The average size of crystallites is in the range 1-5 {mu}m. All samples show semiconductor behaviour in their temperature dependence of resistivity. The electrical conduction mechanism changes from variable-range hopping to the thermally activated mechanism when x > 0.12.
OSTI ID:
20891650
Journal Information:
Materials Research Bulletin, Journal Name: Materials Research Bulletin Journal Issue: 3 Vol. 41; ISSN MRBUAC; ISSN 0025-5408
Country of Publication:
United States
Language:
English