Crystal structure and dielectric properties of complex perovskite (Sr, Ba, Ca)(Ni0.5W0.5)O3

Takashi Fujii, Hiroko Sato, Shigeru Ito, Gary Lynn Messing

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Abstract

A-site cation substitution with Ba2+ and Ca2+ was made for the complex perovskite Sr(Ni0.5W0.5)O 3 to correlate with the structure evolution and the temperature coefficient of dielectric constant. The crystal structures of the solid solutions at elevated temperatures were studied using high temperature X-ray powder diffractometry. A single phase of the perovskite was obtained and ordering of the cations in B-site was observed for all compositions of the solid solutions sintered at 1400 °C for 24 h. The crystal symmetry of the solid solutions at room temperature was changed from monoclinic→rhombohedral→orthorhombic→cubic with the corresponding A-site cation species of Ca2+→Sr 2+→Ba2+. The orthorhombic phase of Sr(Ni 0.5W0.5)O3 was transformed to the cubic phase at 300°C. The phase transformation from rhombohedral to cubic at elevated temperatures was observed for each of the Ca2+-substituted solid solutions, and the phase transformation temperatures increased with increasing Ca2+ content. Another phase transformation from monoclinic to rhombohedral gradually occurred for (Sr0.2Ca0.8)(Ni 0.5W0.5)O3 between 400 and 600°C. Phase transformation was not observed for Ca(Ni0.5W0.5)O 3 in the temperature range from room temperature to 1200°C. Dielectric constants of the solid solutions at room temperature were approximately 27-33. Temperature dependence of dielectric constant was measured in the temperature range from -100 to 500°C and the temperature coefficients of dielectric constant for each of the solid solutions are discussed correlating with the changes in the crystal symmetry during heating.

Original languageEnglish (US)
Pages (from-to)485-489
Number of pages5
JournalSolid State Ionics
Volume172
Issue number1-4 SPEC. ISS.
DOIs
StatePublished - Aug 31 2004

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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