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Mechanism of Formation of Perovskite Phase and Dielectric Properties of Pb(Zn,Mg) 1/3 Nb 2/3 O 3 Ceramics Prepared by Columbite Precursor Routes
Author(s) -
Jang Hyun M.,
Cho Sung R.,
Lee KyuMann
Publication year - 1995
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1995.tb08800.x
Subject(s) - columbite , pyrochlore , perovskite (structure) , materials science , phase (matter) , dielectric , ceramic , inorganic chemistry , mineralogy , crystallography , chemical engineering , chemistry , metallurgy , optoelectronics , organic chemistry , engineering
The mechanism of formation of the perovskite phase and the dielectric properties of Pb(Zn,Mg) 1/3 Nb 2/3 O 3 (PZMN) ceramics were examined using two different types of columbite precursors, (Mg,Zn)Nb 2 O 6 (MZN) and MgNb 2 O 6 + ZnNb 2 O 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 2– x (Zn,Mg) y Nb 2−y O 7− x −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 max (temperature of the dielectric permittivity maximum), indicating a broadened compositional distribution of the B‐site cations in the PbO + MN + ZN system.