研究目的
Investigating the role of zinc in the perovskite formation and dielectric properties of a pseudo-binary system Pb(Mg1/2W1/2)O3-Pb(Fe2/3W1/3)O3 (PMW-PFW) modified by 20 mol% Pb(Zn1/2W1/2)O3 (PZW) doping.
研究成果
The study demonstrated that substitution of 20 mol% PZW into PMW-PFW did not substantially impede perovskite formation, except for a PFW-rich composition. The dielectric properties showed diffused maxima with frequency-dependent dispersion, and the phase transition temperatures decreased sharply at low PFW concentrations. The diffuseness parameters reflected the phase transition modes well, and the degree of dielectric dispersion could predict sharp/diffuse phase transition modes.
研究不足
The presence of secondary phases like Pb2WO5 I and II at certain compositions interfered with the sintering process and perovskite formation. The structural ordering in PMW required extended sintering times, which might not be practical for all applications.
1：Experimental Design and Method Selection:
The study involved the preparation of ceramic samples of a pseudo-binary system PMW-PFW by solid-state reaction, with compositions modified by 20 mol% PZW doping. The B-site precursor method was adopted to assist perovskite formation.
2：Sample Selection and Data Sources:
High-purity chemicals were used as starting materials. The moisture contents of raw materials and prepared B-site precursor powders were measured for batch calculation.
3：List of Experimental Equipment and Materials:
XRD for phase identification, SEM for microstructure examination, and an impedance analyzer for dielectric properties measurement.
4：Experimental Procedures and Operational Workflow:
The B-site precursor powders were wet-milled, dried, and reacted. PbO was added, and the powder batches were wet-milled, dried, and calcined. Polyvinyl alcohol was added, and the powders were pressed into pellets and fired.
5：Data Analysis Methods:
The dielectric constant and loss data were acquired on cooling using an impedance analyzer. The dielectric constant spectra were analyzed in terms of diffuseness characteristics.
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