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 language | English (US) |
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Pages (from-to) | 485-489 |
Number of pages | 5 |
Journal | Solid State Ionics |
Volume | 172 |
Issue number | 1-4 SPEC. ISS. |
DOIs | |
State | Published - Aug 31 2004 |
All Science Journal Classification (ASJC) codes
- General Chemistry
- General Materials Science
- Condensed Matter Physics