Dielectric properties, electrical conductivity, and relaxation phenomena in ferroelectric Bi2WO6

Abstract

Single crystals and polycrystalline Bi2WO6 samples are used to measure the dielectric constant, loss, and electrical conductivity, over a wide range of temperature, oxygen partial pressure in ambient atmosphere, and frequency of the measuring electric field. Maxima of the dielectric constant are observed at phase transitions close to 930 and 960°C. The Curie constant for bismuth tungstate is 1.4 × 105 K, the Curie‐Weiss temperature is equal to 926°C. The electrical conductivity of Bi2WO6 in the range 400 to 700°C is practically purely ionic at oxygen partial pressures of 1 to 10−1 atm, and electronic at PO2 = 10−2 to 10−5 atm. The maxima in the dielectric constant and tan δ in the range from 400 to 700°C, as the investigations of their frequency dispersion and the dependence on the composition of the ambient atmosphere revealed, have a relaxation character and are connected with the formation of two types of defect associates in crystals. The possible nature of crystal lattice defects responsible for electrical conductivity and relaxation phenomena is discussed.

The crystal structure of russellite; a re-determination using neutron powder diffraction of synthetic Bi2WO6

“…At Poona, russellite occurs with bismutite, bismite and koechlinite in a small acid pegmatite vein comprising of quartz and muscovite with minor beryl and wolffamite. The russellite from west Cumbria occurs as a supergene mineral in an assemblage which includes scheelite, ferberite and chalcopyrite as the major hypogene phases in Although russellite remains a poorly characterised minerai species, the artificial compound BizWO6 has been studied in great detail as a result of its exhibiting a number of interesting solidstate and optical properties such as ferroelectri city, piezoelectricity, pyroelectricity and a nonlinear dielectric susceptibility (Newkirk etal., 1972;Stefanovich and Venentsev, 1973;Ismail zade and Mirishli, 1970;Yanovskii et al, 1975;Utkin et al, 1980). The author became interested in BizAO 6 type compounds after the discovery of high oxide-ion conductivity in Bi2UO6 (Bonanos, 1989) (10 -I S cm -~ grain interior conductivity at 400 ~ leading to a survey of the structure and transport properties of compounds with analagous stoichiometries.…”

Evidence of ferroelastic–ferroelastic phase transition in BiMoxW1−xO6 compounds

“…4 As a thin film 5 it can be a serious candidate within the low fatigue Aurivillius ferroelectric family for NVFeRAM systems. One of these anomalies, that corresponding to the temperature close to 940 K, contains mechanoelastic features that strongly suggest that we are dealing with a ferroelastic-ferroelastic phase transition.…”

Multiferroic vertically aligned nanocomposite with CoFe2O4 nanocones embedded in layered Bi2WO6 matrix

“…The strong polarization anisotropy makes it unique for mastering the ferroelectric property by thin film strain effect. However, the work on BWO in thin film form is very scarce [14] and most of the BWO demonstrations have previously focused on dielectric and photocatalytic properties [15,16,17].…”