To make the ferroelectric BaTiO3 possess ferromagnetism simultaneously,magnetic Fe was doped into BaTiO3 ceramics at doping levels up to 10%(molar fraction).Both tetragonal and hexagonal phases coexisted in the Fe-dop...To make the ferroelectric BaTiO3 possess ferromagnetism simultaneously,magnetic Fe was doped into BaTiO3 ceramics at doping levels up to 10%(molar fraction).Both tetragonal and hexagonal phases coexisted in the Fe-doped BaTiO3 ceramics except at 1% doping level.X-ray diffraction analysis indicated that higher doping level of Fe,higher sintering temperature and longer sintering time promoted the formation of hexagonal phases in Fe-doped BaTiO3 ceramics.Ferroelectricity was observed in all samples at room temperature,but it was greatly depressed by Fe doping.Except at doping level of 1%,room-temperature ferromagnetism was observed in the BaTiO3 ceramics.The dependence of the saturation magnetization and coercivities of the Fe-doped BaTiO3 ceramics on doping level was systematically studied.Both the saturation magnetization and magnetic coercivities were found to be dependent on the doping level as well as the fraction of the hexagonal phase in the ceramics.展开更多
Dense nanocrystalline BaTiO3 ceramics with a homogeneous grain size of 30 nm was obtained by pressure assisted sintering. The ferroelectric behaviour of the ceramics was characterized by the dielectric peak at around ...Dense nanocrystalline BaTiO3 ceramics with a homogeneous grain size of 30 nm was obtained by pressure assisted sintering. The ferroelectric behaviour of the ceramics was characterized by the dielectric peak at around 120 ℃, the P-E hysteresis loop and some ferroelectric domains. These experimental results indicate that the critical grain size for the disappearance of ferroelectricity in nanocrystalline BaTiO3 ceramics fabricated by pressure assisted sintering is below 30 nm. The ferroelectric property decreasing with decreasing grain size can be explained by the lowered tetragonality and the ＇dilution＇ effect of grain boundaries.展开更多
Barium titanate, BaTiO3 (BTO) is the most common ferro electric material, which is used to manufacture electronic components such as multilayer capacitors, positive temperature coefficient thermistors, piezo electric ...Barium titanate, BaTiO3 (BTO) is the most common ferro electric material, which is used to manufacture electronic components such as multilayer capacitors, positive temperature coefficient thermistors, piezo electric transdures, and ferro electric memory. Zr doped barium magnesium titanate (Ba0.9Mg1.0)(ZrxTi1-x)O3 (with x = 0.10, 0.20, 0.40 (BMZT 10, BMZT 20 and BMZT 40) perovskite is prepared by conventional solid state reaction method. The starting raw materials were BaCO3, TiO2, MgO and ZrO2. The XRD study at room temperature suggests that these have cubic and tetragonal symmetry phases. The behavior of the measured dielectric permittivity and dielectric loss with temperature and frequency reveals that the materials undergo a diffuse para-ferroelectric phase transition and are of the relaxor type. The crystal structure, surface morphology and dielectric properties of Zr and Mg doped barium titanate ceramics were investigated. Zr4+ and Mg2+ ions have entered the unit cell maintaining the perovskite structure of solid solution without the evidence of any additional phase when Mg content is 0.1 mole% and the Zr content is 0.10, 0.20 and 0.40 mole%.展开更多
BaTiO3/epoxy composites consisting of two three-dimensionally interpenetrating networks of BaTiO3 and epoxy phases were prepared using a new approach. The BaTiO3/epoxy composites exhibit a colossal dielectric constant...BaTiO3/epoxy composites consisting of two three-dimensionally interpenetrating networks of BaTiO3 and epoxy phases were prepared using a new approach. The BaTiO3/epoxy composites exhibit a colossal dielectric constant, low dielectric loss and high flexural strength. In the BaTiO3 networks, chemically bonded grain boundaries between neighboring BaTiO3 grains were established, and they are responsible for the colossal dielectric constant and high flexural strength of the BaTiO3/epoxy composites. Furthermore, unlike the conventional ceramic/polymer composites, this approach also makes high loadings of BaTiO3 contents possible for the BaTiO3/epoxy composites without compromising their high flexural strength.展开更多
基金Project(60661001) supported by the National Natural Science Foundation of China
文摘To make the ferroelectric BaTiO3 possess ferromagnetism simultaneously,magnetic Fe was doped into BaTiO3 ceramics at doping levels up to 10%(molar fraction).Both tetragonal and hexagonal phases coexisted in the Fe-doped BaTiO3 ceramics except at 1% doping level.X-ray diffraction analysis indicated that higher doping level of Fe,higher sintering temperature and longer sintering time promoted the formation of hexagonal phases in Fe-doped BaTiO3 ceramics.Ferroelectricity was observed in all samples at room temperature,but it was greatly depressed by Fe doping.Except at doping level of 1%,room-temperature ferromagnetism was observed in the BaTiO3 ceramics.The dependence of the saturation magnetization and coercivities of the Fe-doped BaTiO3 ceramics on doping level was systematically studied.Both the saturation magnetization and magnetic coercivities were found to be dependent on the doping level as well as the fraction of the hexagonal phase in the ceramics.
文摘Dense nanocrystalline BaTiO3 ceramics with a homogeneous grain size of 30 nm was obtained by pressure assisted sintering. The ferroelectric behaviour of the ceramics was characterized by the dielectric peak at around 120 ℃, the P-E hysteresis loop and some ferroelectric domains. These experimental results indicate that the critical grain size for the disappearance of ferroelectricity in nanocrystalline BaTiO3 ceramics fabricated by pressure assisted sintering is below 30 nm. The ferroelectric property decreasing with decreasing grain size can be explained by the lowered tetragonality and the ＇dilution＇ effect of grain boundaries.
文摘Barium titanate, BaTiO3 (BTO) is the most common ferro electric material, which is used to manufacture electronic components such as multilayer capacitors, positive temperature coefficient thermistors, piezo electric transdures, and ferro electric memory. Zr doped barium magnesium titanate (Ba0.9Mg1.0)(ZrxTi1-x)O3 (with x = 0.10, 0.20, 0.40 (BMZT 10, BMZT 20 and BMZT 40) perovskite is prepared by conventional solid state reaction method. The starting raw materials were BaCO3, TiO2, MgO and ZrO2. The XRD study at room temperature suggests that these have cubic and tetragonal symmetry phases. The behavior of the measured dielectric permittivity and dielectric loss with temperature and frequency reveals that the materials undergo a diffuse para-ferroelectric phase transition and are of the relaxor type. The crystal structure, surface morphology and dielectric properties of Zr and Mg doped barium titanate ceramics were investigated. Zr4+ and Mg2+ ions have entered the unit cell maintaining the perovskite structure of solid solution without the evidence of any additional phase when Mg content is 0.1 mole% and the Zr content is 0.10, 0.20 and 0.40 mole%.
基金Funded by the National Natural Science Foundation of China(Nos.21571095 and 51362020)the Jiangxi Provincial Department of Education(KJLD13008)
文摘BaTiO3/epoxy composites consisting of two three-dimensionally interpenetrating networks of BaTiO3 and epoxy phases were prepared using a new approach. The BaTiO3/epoxy composites exhibit a colossal dielectric constant, low dielectric loss and high flexural strength. In the BaTiO3 networks, chemically bonded grain boundaries between neighboring BaTiO3 grains were established, and they are responsible for the colossal dielectric constant and high flexural strength of the BaTiO3/epoxy composites. Furthermore, unlike the conventional ceramic/polymer composites, this approach also makes high loadings of BaTiO3 contents possible for the BaTiO3/epoxy composites without compromising their high flexural strength.
