Solid-State Reactions Occurring during the Synthesis of CaTiO3-NdAlO3 Perovskite Solid Solutions
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- 作者：Bostjan Jancar ; Matjaz Valant ; and Danilo Suvorov
- 刊名：Chemistry of Materials
- 出版年：2004
- 出版时间：March 23, 2004
- 年：2004
- 卷：16
- 期：6
- 页码：1075 - 1082
- 全文大小：278K
- 年卷期：v.16,no.6(March 23, 2004)
- ISSN：1520-5002
文摘
The X-ray powder-diffraction technique was used to investigate the solid-state reactionpaths to the 0.7CaTiO3-0.3NdAlO3 perovskite solid solution. The results show that theperovskite phases CaTiO3 and NdAlO3 are formed prior to the solid solution, regardless ofthe combination of oxide powders used as reagents. The two perovskites subsequently reactto form a solid solution at temperatures above 1200 
C. The reaction between CaTiO3 andNdAlO3 was studied using a diffusion couple, which revealed that the slower kinetics ofincorporation of the Al into the forming solid solution results in the formation of anintermediate phase based on hexaluminate CaAl12O19. The presence of such inclusions resultsin the formation of defects in the perovskite matrix phase, which adversely affects thedielectric losses of the sintered ceramics based on the 0.7CaTiO3-0.3NdAlO3 solid solution.To minimize the concentration of CaAl12O19-based inclusions, a thorough calcinationprocedure with intermediate homogenizations needs to be conducted at temperatures above1300 C.
C. The reaction between CaTiO3 andNdAlO3 was studied using a diffusion couple, which revealed that the slower kinetics ofincorporation of the Al into the forming solid solution results in the formation of anintermediate phase based on hexaluminate CaAl12O19. The presence of such inclusions resultsin the formation of defects in the perovskite matrix phase, which adversely affects thedielectric losses of the sintered ceramics based on the 0.7CaTiO3-0.3NdAlO3 solid solution.To minimize the concentration of CaAl12O19-based inclusions, a thorough calcinationprocedure with intermediate homogenizations needs to be conducted at temperatures above1300 C.