BaGeO₃ as sintering additive for BaTiO₃–MgFe₂O₄ composite ceramics

Abstract

BaTiO3−MgFe2O4 composites (30 wt.% MgFe2O4) with a small addition of BaGeO3 as a sintering additive were synthesized by a one-pot Pechini-like sol-gel process. Nano-crystalline composite powders with a crystallite size of about 10 nm were obtained after reaction at 700 °C for 1 h. Magnetic investigations suggest that the nano-powder is in its superparamagnetic state at room temperature. The addition of BaGeO3 leads to an improved sintering behaviour. DTA measurements reveal the formation of a liquid phase at 1164(3) °C. Dense ceramic bodies (relative density ≥ 90 %) were obtained after sintering for 1 h at 1150 °C. SEM investigations prove a 0-3 connectivity and show that the addition of BaGeO3 promotes the grain growth leading to particles up to 4 µm. In contrast, fine-grained composite ceramics with smaller particles up to 230 nm were obtained after a two-step sintering process. Magnetic measurements indicate a ferrimagnetic behaviour with coercivity values up to 70 Oe depending on the sintering procedure. Furthermore, addition of BaGeO3 results in an increase of the relative permittivity, whereas the dissipation factor slightly decreases. Please do not adjust margins Please do not adjust margins measured range is shown. (B) Detail of the XRD patterns in the range of 2θ = 30−36 ° of BT0.95G0.05−MF−0.3 and BT1.0G0.05−MF−0.3 sintered at 1250 °C.

Novel magnetoelectric composites of cobalt iron alloy and barium titanate

“…In contrast to composites of BaTiO 3 with ferrite spinels, the influence of the Co 1/3 Fe 2/3 alloy on the dielectric properties is comparatively low . Usually, ferrite‐BaTiO 3 composites show Maxwell‐Wagner‐like frequency and temperature dependencies of ε r that are distinctively different from pure BaTiO 3 . The Co 1/3 Fe 2/3 –BaTiO 3 composites, on the other hand, show only little deviations compared to pure BaTiO 3 .…”

Hysteretic magnetoelectric behavior of CoFe2O4–BaTiO3 composites prepared by reductive sintering and reoxidation

“…The occurrence of the maximum is accompanied by an increase in the loss tangent and can be assigned to the ferroelectric-paraelectric transition of BaTiO 3 . [29][30][31][32] For large-grained BaTiO 3 this phase transition occurs at 120 1C.…”

Novel magnetoelectric composites of cobalt iron alloy and barium titanate

“…22 Usually, ferrite-BaTiO 3 composites show Maxwell-Wagner like frequency and temperature dependencies of e r that are distinctively different from pure BaTiO 3 . [25][26][27] The Co 1/3 Fe 2/3 -BaTiO 3 composites, on the other hand, show only little deviations compared to pure BaTiO 3 . A similar behavior has already been reported for Ni-BaTiO 3 composites.…”