High temperature dielectric properties and magnetic behavior of K1–xCaxNbO3 ceramic

Published on Feb 1, 2021in Physica B-condensed Matter2.436
· DOI :10.1016/J.PHYSB.2020.412593
Guilin Song2
Estimated H-index: 2
(Henan Normal University),
Yichen Song1
Estimated H-index: 1
(SEU: Southeast University)
+ 4 AuthorsNa Zhang3
Estimated H-index: 3
(Henan Normal University)
Source
Abstract
Abstract K1-xCaxNbO3 (x = 0–0.2) ceramic samples were prepared by self-sacrifice method to study the effects of Ca2+ doping on the crystal structure, dielectric properties and magnetic phase transition of KNbO3. XRD analysis showed that all samples belong to a single-phase orthogonal crystal system with a spatial group of Amm2. The valence states of K, Nb and O elements, the atomic proportion in K1-xCaxNbO3 (x = 0–0.2) samples, and the relationship between the binding energies of K, Nb and O and x were studied through XPS. SEM showed that Ca2+ doping had a significant regulation effect on the micromorphology and grain size of KNO samples. Two transitions were observed in er -T of KNbO3, the first transition was at 213 °C and the second transition was at 424 °C, corresponding to the ferroelectric phase transition from the orthogonal phase to the tetragonal phase and from the tetragonal phase to the cubic phase, respectively. The TC decreased from 424 °C to 415 °C with the increase of x. The variation relationship of M-T of K1-xCaxNbO3 (x = 0–0.2) samples within the range of 5-350k was measured. It is found from M-T curve that the M of KNO sample is positive when T   Td. This conclusion was confirmed by testing the M-H variation relationship, providing experimental basis for the diamagnetism of KNO at room temperature.
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