2022. 11. 20. 18:59ㆍMaterial
CARTS USA 2006
Pascal Pinceloup, Michael Randall and Abhijit Gurav
ABSTRACT
The effects of manganese addition and A/B ratio on the microstructure, grain size and insulation resistance of CaZrO3-based BME multilayer ceramic capacitors were investigated. The results are discussed in terms of Mn distribution and site occupancy in the CaZrO3 perovskite lattice.
CONCLUSIONS
1. CaZrO3 behaves similarly to BaTiO3 regarding the effect of excess A or B site ions on densification and grain growth. There is evidence of a limited solid solubility of ZrO2 in CaZrO3, but a Zr-rich second phase appears when the solubility limit is exceeded.
2. Additions of MnO2 retards densification and grain growth slightly for less than about 2 mol% Mn but densification is promoted for higher levels of Mn. Full incorporation of Mn in CaZrO3 as well as good densification is possible if sufficient grain growth occurs, which can be accomplished with Ca/Zr<1. In absence of grain growth Mn remains on the grain boundaries.
3. IR of Mn-doped CaZrO3 depends on the degree of incorporation of Mn on the lattice. Best IR values are obtained for full incorporation of Mn on the lattice (large grains). In the case of full incorporation, 1 mol% Mn increases IR of 1 order of magnitude compared to undoped samples. This effect is believed to be due to the locking of the valence state of Mn as Mn2+ inside large grains.
4. The apparently large solubility limit of Mn in CaZrO3 suggests that Mn2+ may be able to occupy both A and B sites of CaZrO3, which is supported by experimental evidence as well as the intermediate size of the Mn2+ ion compared to Ca2+ and Zr4+ ions.
DOI: 10.13140/RG.2.1.4607.4321