TY - JOUR
T1 - High-pressure dielectric behavior of polycrystalline CaMoO4
T2 - The role of grain boundaries
AU - Qin, Tianru
AU - Wang, Qinglin
AU - Yue, Donghui
AU - Shen, Wenshu
AU - Yan, Yalan
AU - Han, Yonghao
AU - Ma, Yanzhang
AU - Gao, Chunxiao
N1 - Publisher Copyright:
© 2017 Elsevier B.V.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2018
Y1 - 2018
N2 - The dielectric behavior of polycrystalline CaMoO4 was investigated at pressures up to 36.0 GPa using in situ impedance measurements. Grain boundaries played a dominant role in the electrical transport process. Grain boundary microstructures rearranged with the application of pressures, and the relaxation activation energy increased with increasing pressure in the tetragonal phase but decreased in the monoclinic phase. The variation of the bulk resistance with pressure was attributed to defects generated during the compression. The increasing grain boundary resistance with pressure in the tetragonal phase was caused by the increased number of dangling bonds. In the tetragonal phase, localization around O atoms weakened with increasing pressure, which promoted the polarization of Mo–O electric diploes and led to an increase of the relative dielectric constant. In addition, the dielectric loss tangent of CaMoO4 was significantly reduced in the low frequency range after a pressure cycle. This work demonstrates that regulation of the polycrystalline dielectric performance by modifying the grain boundary distribution under compression can be used as an effective method to improve the bulk properties of ABO4-type dielectrics.
AB - The dielectric behavior of polycrystalline CaMoO4 was investigated at pressures up to 36.0 GPa using in situ impedance measurements. Grain boundaries played a dominant role in the electrical transport process. Grain boundary microstructures rearranged with the application of pressures, and the relaxation activation energy increased with increasing pressure in the tetragonal phase but decreased in the monoclinic phase. The variation of the bulk resistance with pressure was attributed to defects generated during the compression. The increasing grain boundary resistance with pressure in the tetragonal phase was caused by the increased number of dangling bonds. In the tetragonal phase, localization around O atoms weakened with increasing pressure, which promoted the polarization of Mo–O electric diploes and led to an increase of the relative dielectric constant. In addition, the dielectric loss tangent of CaMoO4 was significantly reduced in the low frequency range after a pressure cycle. This work demonstrates that regulation of the polycrystalline dielectric performance by modifying the grain boundary distribution under compression can be used as an effective method to improve the bulk properties of ABO4-type dielectrics.
KW - CaMoO
KW - Dielectric properties
KW - Grain boundary
KW - High pressure
UR - http://www.scopus.com/inward/record.url?scp=85030117776&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2017.09.286
DO - 10.1016/j.jallcom.2017.09.286
M3 - Article
AN - SCOPUS:85030117776
VL - 730
SP - 1
EP - 6
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
SN - 0925-8388
ER -