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Ba3ZnTa2− xNbxO9and Ba3MgTa2− xNbxO9(0≤x≤1): synthesis, structure and dielectric properties

Authors
Journal
Materials Research Bulletin
0025-5408
Publisher
Elsevier
Publication Date
Volume
37
Issue
14
Identifiers
DOI: 10.1016/s0025-5408(02)00933-9
Keywords
  • A. Oxides
  • B. Chemical Synthesis
  • C. X-Ray Diffraction
  • D. Dielectric Properties

Abstract

Abstract Oxides belonging to the families Ba 3ZnTa 2− x Nb x O 9 and Ba 3MgTa 2− x Nb x O 9 were synthesized by the solid state reaction route. Sintering temperatures of 1300°C led to oxides with disordered (cubic) perovskite structure. However, on sintering at 1425°C hexagonally ordered structures were obtained for Ba 3MgTa 2− x Nb x O 9 over the entire range (0≤ x≤1) of composition, while for Ba 3ZnTa 2− x Nb x O 9 the ordered structure exists in a limited range (0≤ x≤0.5). The dielectric constant is close to 30 for the Ba 3ZnTa 2− x Nb x O 9 family of oxides while the Mg analogues have lower dielectric constant of ∼18 in the range 50 Hz to 500 kHz. At microwave frequencies (5–7 GHz) dielectric constant increases with increase in niobium concentration (22–26) for Ba 3ZnTa 2− x Nb x O 9; for Ba 3MgTa 2− x Nb x O 9 it varies between 12 and 14. The “Zn” compounds have much higher quality factors and lower temperature coefficient of resonant frequency compared to the “Mg” analogues.

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