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A structure, conductivity and dielectric properties investigation of A3CoNb2O9 (A=Ca, Sr, Ba) triple perovskites |
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| Authors: | V Ting L Norén DJ Goossens C Ferraris |
| Institution: | a Research School of Chemistry, The Australian National University, Solid State Structural Chemistry, Canberra, ACT 0200, Australia b Bragg Institute, Australian Nuclear Science and Technology Organisation, PMB 1, Menai NSW 2234, Australia c Institute of Environmental Science and Engineering, Nanyang Technological University (NTU), Innovation Centre Block 2, Unit 247, 18 Nanyang Drive, Singapore 637723, Singapore |
| Abstract: | The room temperature structures as well as the temperature-dependent conductivity and dielectric properties of the A3CoNb2O9 (A=Ca2+, Sr2+ and Ba2+) triple perovskites have been carefully investigated. A constrained modulation wave approach to Rietveld structure refinement is used to determine their room temperature crystal structures. Correlations between these crystal structures and their physical properties are found. All three compounds undergo insulator to semiconductor phase transitions as a function of increasing temperature. The hexagonal Ba3CoNb2O9 compound acts as an insulator at room temperature, while the monoclinic Ca3CoNb2O9 compound is already a semiconductor at room temperature. The measured dielectric frequency characteristics of the A=Ba compound are excellent. |
| Keywords: | A3CoNb2O9 complex perovskites Dielectric properties Resistivity insulator to semiconductor phase transitions Rietveld refinement |
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