Features of the Structure and Electrophysical Properties of Solid Solutions of the System (1-x-y) NaNbO3-xKNbO3-yCd0.5NbO3

Ferroelectric ceramic materials based on the (1-x-y) NaNbO3-xKNbO3-yCd0.5NbO3 system (x = 0.05–0.65, y = 0.025–0.30, Δx = 0.05) were obtained by a two-stage solid-phase synthesis followed by sintering using conventional ceramic technology. It was found that the region of pure solid solutions extends...

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Bibliographic Details
Published in:Materials 2021-07, Vol.14 (14), p.4009
Main Authors: Andryushin, Konstantin, Shilkina, Lidiya, Andryushina, Inna, Nagaenko, Alexandr, Moysa, Maxim, Dudkina, Svetlana, Reznichenko, Larisa
Format: Article
Language:English
Subjects:
Cadmium
Ceramics
Density
Ferroelectric materials
Ferroelectricity
Liquid phases
Phase transitions
Potassium
Potassium carbonate
Potassium niobates
Recrystallization
Room temperature
Sintering
Sodium
Sodium carbonate
Sodium compounds
Solid phase synthesis
Solid solutions
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Summary:Ferroelectric ceramic materials based on the (1-x-y) NaNbO3-xKNbO3-yCd0.5NbO3 system (x = 0.05–0.65, y = 0.025–0.30, Δx = 0.05) were obtained by a two-stage solid-phase synthesis followed by sintering using conventional ceramic technology. It was found that the region of pure solid solutions extends to x = 0.70 at y = 0.05 and, with increasing y, it narrows down to x ≤ 0.10 at y = 0.25. Going out beyond the specified concentrations leads to the formation of a heterogeneous region. It is shown that the grain landscape of all studied ceramics is formed during recrystallization sintering in the presence of a liquid phase, the source of which is unreacted components (Na2CO3 with Tmelt. = 1126 K, K2CO3 with Tmelt. = 1164 K, KOH with Tmelt. = 677 K) and low-melting eutectics in niobate mixtures (NaNbO3, Tmelt. = 1260 K, KNbO3, Tmelt. = 1118 K). A study of the electrophysical properties at room temperature showed the nonmonotonic behavior of all dependences with extrema near symmetry transitions, which corresponds to the logic of changes in the electrophysical parameters in systems with morphotropic phase boundaries. An analysis of the evolution of dielectric spectra made it possible to distinguish three groups of solid solutions: classical ferroelectrics (y = 0.05–0.10), ferroelectrics with a diffuse phase transition (y = 0.30), and ferroelectrics relaxors (y = 0.15–0.25). A conclusion about the expediency of using the obtained data in the development of materials and devices based on such materials has been made.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma14144009