Phase structure, piezoelectric and multiferroic properties of SmCoO3-modified BiFeO3-BaTiO3 lead-free ceramics

(0.75−x)BiFeO3-0.25BaTiO3-xSmCoO3 + 1 mol.% MnO2 lead-free multiferroic ceramics were synthesized by a conventional ceramic fabrication technique. The effects of SmCoO3 on phase structure, piezoelectricity and multiferroicity of the ceramics were studied. All the ceramics can be well sintered at a low sintering temperature of 960°C. The crystalline structure of the ceramics is transformed from rhombohedral to tetragonal symmetry with increasing the amount of SmCoO3. A morphotropic phase boundary of rhombohedral and tetragonal phases is formed at x = 0.01–0.04. A small amount of SmCoO3 is shown to improve the ferroelectric, piezoelectric and magnetoelectric properties of the ceramics. For the ceramics with x = 0.01–0.03, enhanced resistivity (R ∼ 1.2 × 109 Ω cm to 2.1 × 109 Ω cm), piezoelectricity (d 33 ∼ 65 pC/N to 106 pC/N) and ferroelectricity (P r ∼ 6.38 μC/cm2 to 22.89 μC/cm2) are obtained. The ferromagnetism of the materials is greatly enhanced by the doping of SmCoO3 such that a very high magnetoelectric coefficient of ∼742 mV/(cm Oe) is obtained at x = 0.01, suggesting a promising potential in multiferroic devices

Phase structure and electrochemical performance of layered-spinel integrated LiNi0.5Mn0.5O2-LiMn1.9Al0.1O4 composite cathodes for lithium ion batteries

In recent years, multi-component integrated composite cathodes for lithium ion batteries have attracted considerable attention. In this work, novel layered-spinel integrated cathode materials of (1−x)LiNi0.5Mn0.5O2-xLiMn1.9Al0.1O4 were synthesized by a sol-gel method, and their phase structures, morphologies and electrochemical performance were investigated. The crystal structure of the (1−x)LiNi0.5Mn0.5O2-xLiMn1.9Al0.1O4 is changed from layered to spinel structure with increasing x. All the samples exhibit nanoscale grains with the minimum grain size of ~130 nm when x = 0.5. The composite electrode with x = 0.5 exhibits the optimal discharge capacity, presenting a large initial discharge capacity of 236 mAh g−1 at the current density of 20 mA g−1. Good rate capability is also obtained at the composite electrode with x = 0.5 where the electrode displays the relatively high discharge capacity of 64.9 mAh g−1 at the high rate of 5 C. The improved electrochemical performance is related to the introduction of spinel structure into layered structure and small grain size. The spinel structure can stabilize the layered structure, which leads to the improvement in the electrochemical performance of the composites; and the small grain size in the sample with x = 0.5 provides short lithium ion diffusion way and thus enhances the electrochemical performance

Phase Structure, Piezoelectric and Multiferroic Properties of SmCoO3-Modified BiFeO3-BaTiO3 Lead-Free Ceramics

(0.75-x)BiFeO3-0.25BaTiO(3)-xSmCoO(3) + 1 mol.% MnO2 lead-free multiferroic ceramics were synthesized by a conventional ceramic fabrication technique. The effects of SmCoO3 on phase structure, piezoelectricity and multiferroicity of the ceramics were studied. All the ceramics can be well sintered at a low sintering temperature of 960A degrees C. The crystalline structure of the ceramics is transformed from rhombohedral to tetragonal symmetry with increasing the amount of SmCoO3. A morphotropic phase boundary of rhombohedral and tetragonal phases is formed at x = 0.01-0.04. A small amount of SmCoO3 is shown to improve the ferroelectric, piezoelectric and magnetoelectric properties of the ceramics. For the ceramics with x = 0.01-0.03, enhanced resistivity (R 1.2 x 10(9) Omega cm to 2.1 x 10(9) Omega cm), piezoelectricity (d (33) 65 pC/N to 106 pC/N) and ferroelectricity (P (r) 6.38 mu C/cm(2) to 22.89 mu C/cm(2)) are obtained. The ferromagnetism of the materials is greatly enhanced by the doping of SmCoO3 such that a very high magnetoelectric coefficient of 742 mV/(cm Oe) is obtained at x = 0.01, suggesting a promising potential in multiferroic devices.Department of Electrical Engineerin