Mechanism of formation of perovskite phase and dielectric properties of Pb(Zn,Mg){sub 1/3}Nb{sub 2/3}O{sub 3} ceramics prepared by columbite precursor routes
- Pohang Univ. of Science and Technology (Korea, Republic of)
The mechanism of formation of the perovskite phase and the dielectric properties of Pb(Zn,Mg){sub 1/3}Nb{sub 2/3}O{sub 3} (PZMN) ceramics were examined using two different types of columbite precursors, (Mg,Zn)Nb{sub 2}O{sub 6} (MZN) and MgNb{sub 2}O{sub 6} + ZnNb{sub 2}O{sub 6} (MN + ZN). The formation of perovskite phase in the PbO + MN + ZN system is characterized by an initial rapid formation of Mg-rich perovskite phase, followed by a sluggish formation of Zn-rich perovskite phase. On the other hand, due to the formation of pyrochlore phase of mixed divalent cations Pb{sub 2{minus}x}(Zn,Mg){sub y}Nb{sub 2{minus}y}O{sub 7{minus}x{minus}3y/2}, the pyrochlore/perovskite transformation in the PbO + MZN system proceeded uniformly with a spatial homogeneity. Further analysis suggested that the formation of perovskite phase is a diffusion-controlled process. The degree of diffuseness of the rhombohedral/cubic phase transition (DPT) is higher in the PbO + MN + ZN system than in the PbO + MZN specimen for T > T{sub max} (temperature of the dielectric permittivity maximum), indicating a broadened compositional distribution of the B-site cations in the PbO + MN + ZN system.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 79801
- Journal Information:
- Journal of the American Ceramic Society, Vol. 78, Issue 2; Other Information: PBD: Feb 1995
- Country of Publication:
- United States
- Language:
- English
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