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 strontium titanate( Ba_0.8)Sr_(0.2)TiO_(3),BST)nanocrystalline ceramics have been synthesized by high energy ball milling.As the sintering temperature increases from 1200℃to 1350℃,the average grain size of BS...Barium strontium titanate( Ba_0.8)Sr_(0.2)TiO_(3),BST)nanocrystalline ceramics have been synthesized by high energy ball milling.As the sintering temperature increases from 1200℃to 1350℃,the average grain size of BST ceramics increases from 86 nm to 123 nm.The X-ray diffraction(XRD)studies show that these ceramics are tetragonal.The phase and grain size of the sintered pellets have been estimated from the XRD patterns,scanning electron microscopy(SEM)and transmission electron microscopy(TEM)images.The effect of grain size on dielectric and ferroelectric properties is studied.The dielectric and piezoelectric parameters are greatly improved at room temperature with increase in grain size.The Curie transition temperature is found to shift slightly towards higher temperatures as the grain increases from 86 nm to 123 nm.The coercive field decreases and the remnant polarization and spontaneous polarization increase as the grain size of BST nano ceramics increases.These ceramics are promising materials for tunable capacitor device applications.展开更多
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 strontium titanate( Ba_0.8)Sr_(0.2)TiO_(3),BST)nanocrystalline ceramics have been synthesized by high energy ball milling.As the sintering temperature increases from 1200℃to 1350℃,the average grain size of BST ceramics increases from 86 nm to 123 nm.The X-ray diffraction(XRD)studies show that these ceramics are tetragonal.The phase and grain size of the sintered pellets have been estimated from the XRD patterns,scanning electron microscopy(SEM)and transmission electron microscopy(TEM)images.The effect of grain size on dielectric and ferroelectric properties is studied.The dielectric and piezoelectric parameters are greatly improved at room temperature with increase in grain size.The Curie transition temperature is found to shift slightly towards higher temperatures as the grain increases from 86 nm to 123 nm.The coercive field decreases and the remnant polarization and spontaneous polarization increase as the grain size of BST nano ceramics increases.These ceramics are promising materials for tunable capacitor device applications.
