Influence of charged walls and defects on DC resistivity and dielectric relaxations in Cu-Cl boracite

TY - JOUR

T1 - Influence of charged walls and defects on DC resistivity and dielectric relaxations in Cu-Cl boracite

AU - Cochard, Charlotte

AU - Granzow, Torsten

AU - Fernandez-Posada, C. M.

AU - Carpenter, M. A.

AU - McQuaid, Raymond G. P.

AU - Guy, Joseph G. M.

AU - Whatmore, Roger W.

AU - Gregg, J. Marty

N1 - Funding Information: The assistance of C. J. Brierley at Plessey Research (Caswell) Ltd., in growing the boracite crystals is gratefully acknowledged. The authors acknowledge funding from the Engineering and Physical Sciences Research Council (EPSRC: Nos. EP/P02453X/1 and EP/P020194/1) and the U.S.-Ireland Research and Development Partnership Programme (No. USI 120). Publisher Copyright: © 2021 Author(s).

PY - 2021/11/19

Y1 - 2021/11/19

N2 - Charged domain walls form spontaneously in Cu-Cl boracite on cooling through the phase transition. These walls exhibit changed conductivity compared to the bulk and motion consistent with the existence of negative capacitance. Here, we present the dielectric permittivity and DC resistivity of bulk Cu-Cl boracite as a function of temperature (−140 to 150 °C) and frequency (1 mHz to 10 MHz). The thermal behavior of the two observed dielectric relaxations and the DC resistivity is discussed. We propose that the relaxations can be explained by the existence of point defects, most likely local complexes created by a change of valence of Cu and accompanying oxygen vacancies. In addition, the sudden change in resistivity seen at the phase transition suggests that conductive domain walls contribute significantly to the conductivity in the ferroelectric phase.

AB - Charged domain walls form spontaneously in Cu-Cl boracite on cooling through the phase transition. These walls exhibit changed conductivity compared to the bulk and motion consistent with the existence of negative capacitance. Here, we present the dielectric permittivity and DC resistivity of bulk Cu-Cl boracite as a function of temperature (−140 to 150 °C) and frequency (1 mHz to 10 MHz). The thermal behavior of the two observed dielectric relaxations and the DC resistivity is discussed. We propose that the relaxations can be explained by the existence of point defects, most likely local complexes created by a change of valence of Cu and accompanying oxygen vacancies. In addition, the sudden change in resistivity seen at the phase transition suggests that conductive domain walls contribute significantly to the conductivity in the ferroelectric phase.

UR - https://www.scopus.com/pages/publications/85120167444

U2 - 10.1063/5.0067846

DO - 10.1063/5.0067846

M3 - Article

SN - 0003-6951

VL - 119

JO - Applied Physics Letters

JF - Applied Physics Letters

IS - 20

M1 - 202904

ER -