Combustion synthesis, structural, magnetic and dielectric properties of Gd3+-doped lead molybdato-tungstates

Abstract

Gd 3+-doped lead molybdato-tungstates with the chemical formula of Pb 1-3x x Gd 2x (MoO 4) 1-3x (WO 4) 3x (where x = 0.0455, 0.0839, 0.1430, corresponding to 9.53, 18.32, 33.37 mol% of Gd 3+ , respectively, as well as denotes cationic vacancies) were successfully synthesized via combustion route. The XRD and SEM results confirmed the formation of single-phase, tetragonal scheelite-type materials (space group I4 1 /a) with the uniform, spherical and oval grains ranging from 5 to 20 m. Individual grains are strongly agglomerated into big clusters with the size even above 50 m. The magnetic measurements as well as the Brillouin fitting procedure showed paramagnetic state with characteristic superparamagnetic-like behaviour and the short-range ferromagnetic interactions. The electrical and broadband dielectric spectroscopy studies revealed insulating properties with the residual electrical n-type conduction of 2×10-9 S/m and low energy loss (tan  0.01) below 300 K. Dielectric analysis showed that no dipole relaxation processes in the Gd 3+-doped materials were observed. A fit of dielectric loss spectra of Gd 3+-doped samples by sum of the conductivity and the Havriliak-Negami, Cole-Cole, and Cole-Davidson functions confirmed this effect.

Recent advances in electrospun magnetic nanofibers and their applications

“…22 Only when the thermal disturbance is lower than the exchange interaction can magnetic order be formed. There are three main types of magnetic order structures, namely ferromagnetic (FM) order, [23][24][25][26][27][28][29] antiferromagnetic (AFM) order 23,26,[30][31][32] and ferrimagnetic (FI) order. [33][34][35][36] Among them, the exchange interaction in the FM material forces the spins to be arranged in the same direction, so the material exhibits strong magnetism.…”

Gd/Mn Co-Doped CaBi4Ti4O15 Aurivillius-Phase Ceramics: Structures, Electrical Conduction and Dielectric Relaxation Behaviors

“…Until now, many studies about CBT have been reported that concentrated on the structures and how to improve the T c or piezoelectricity [ 14 , 15 , 16 ]. For example, Gd 3+ was found to reduce the leakage current and low loss [ 17 ]. Generally, the p -type conduction is mainly a conducting type for Aurivillius piezoceramics.…”

New Gd3+ and Mn2+-Co-Doped Scheelite-Type Ceramics—Their Structural, Optical and Magnetic Properties

“…Dielectric studies of Gd 3+ -doped scheelite-type molybdates and molybdato-tungstates provided much important information on their properties and potential applications [ 22 , 23 ]. These materials are insulators with a residual electrical n -type conduction not extending 2·10 −9 S/m and a direct (or indirect) band gap energy higher than 3 eV [ 24 , 25 , 26 , 27 ]. The chemical compatibilities of Gd 3+ -doped micro- and nanomaterials with metallic aluminium and silver as intrinsic electrodes make them suitable for LTCC (Low-Temperature Co-fired Ceramic) technology [ 26 ].…”

“…The chemical compatibilities of Gd 3+ -doped micro- and nanomaterials with metallic aluminium and silver as intrinsic electrodes make them suitable for LTCC (Low-Temperature Co-fired Ceramic) technology [ 26 ]. Some of them, e.g., Pb 1−3 x ▯ x Gd 2 x (MoO 4 ) 1−3 x (WO 4 ) 3 x where 0 < x ≤ 0.1774 exhibit electrical relaxation processes [ 26 , 27 ]. These properties of scheelite-type materials lead to the conclusion that they are very good candidates for the fabrication of lossless capacitors.…”