Structure and dielectric properties of solid solutions Bi₇Ti4+xW_xNb1−2x−0.1V0.1O21 (x=0.1−0.4)

Abstract

The structural and electrophysical characteristics of a number of solid solutions of layered oxides of the perovskite-type Bi7[Formula: see text]Wx[Formula: see text][Formula: see text][Formula: see text] ([Formula: see text]) are studied. According to X-ray powder diffraction data, all the compounds studied are single-phase and have the structure of Aurivillius phases ([Formula: see text]) with a rhombic crystal lattice (space group I2[Formula: see text]cm, [Formula: see text]). Changes in tetragonal and rhombic distortions of perovskite-like layers in compounds were considered depending on their chemical composition. The temperature dependences of the relative permittivity [Formula: see text] (T) were measured. It was shown that the Curie temperature [Formula: see text] of the perovskite-type oxides Bi7[Formula: see text]Wx[Formula: see text][Formula: see text][Formula: see text] ([Formula: see text]) linearly decreases with increasing parameter [Formula: see text]. The activation energies of charge carriers were obtained in different temperature ranges. It was found that there are three temperature regions with very different activation energies due to the different nature of the charge carriers in the studied compounds. The effect of substitution of [Formula: see text] ions by [Formula: see text] ions is investigated. It was found that for a number of compounds, the substitution of niobium ions by vanadium ions led to an increase in the dielectric constant and a decrease in the dielectric loss tangent.

Crystal structure, chemical bond characteristics, infrared reflection spectrum, and microwave dielectric properties of Nd 2(Zr 1− x Ti x ) 3(MoO 4) 9 ceramics

“…In this experiment, high-purity powders including Nd 2 O 3 (99.99%, Aladdin), ZrO 2 (99.99%, Aladdin), MoO 3 (99.95%, Aladdin), and TiO 2 (99.99%, Aladdin) were used to synthesize NZ 1−x T x M (x = 0.02-0.10) ceramics by a solid-phase process [28][29][30]. The raw powders with precise weight were put into a ball mill tank with ZrO 2 and C 2 H 5 OH, and then ground with a ball mill for 12 h. After drying at 65 , these powders ℃ were calcined at 700 for 2 h in air.…”

New Piezoceramic SrBi2Nb2-2xWxSnxO9: Crystal Structure, Microstructure and Dielectric Properties

“…The crystal structure of ASPs includes alternating layers of [Bi2O2] 2+ , separated by perovskitelike layers of [Am-1BmO3m+1] 2-, where the A-ions have large radii (Bi 3+ [8], Ca 2+ , Gd 3+ [9], Sr 2+ , Ba 2+ , Pb 2+ , Na + , K + , Y 3+ [10], Ln 3+ , Nd 3+ [11], Lu 3+ [12] (lanthanides) and demonstrate dodecahedral coordination. The B-positions in the oxygen octahedra are occupied by highly charged (≥ 3+) small-radius cations (Ti 4+ , Nb 5+ , Ta 5+ [13], W 6+ [14], Mo 6+ , Fe 3+ , Mn 4+ , Cr 3+ , Ga 3+ [15], etc.). The value of m is determined by the number of perovskite layers [Am-1BmO3m+1] 2− , located between the fluorite-like layers of [Bi2O2] 2+ along the pseudo-tetragonal c-axis (001), and can be an integer or half-integer number in the range m = 1 -6.…”

Aliovalent Calcium Substitution: An Effective Way to Enhance the Magnetoelectric Coupling Properties of Multiferroic BiFeO3

“…[11,12] Solid solution preparation has been experimented as a strong means to improve electrical characteristics as well as tuning the magnetic parameters. [13][14][15][16] The method is found to be useful in tailoring the FE properties also. [17,18] However, in single-phase systems, cationic substitution at the A site is reported to increase the intrinsic properties such as FE, magnetic, and magnetoelectric properties of the system.…”