Dielectric studies were carried out on a lead free Sodium Bismuth Titanate,NBT,(Na_(0.5)Bi_(0.5)TiO_(3))composition.The material was synthesized by conventional ceramic method(CS)and microwave sintering(MS).The presen...Dielectric studies were carried out on a lead free Sodium Bismuth Titanate,NBT,(Na_(0.5)Bi_(0.5)TiO_(3))composition.The material was synthesized by conventional ceramic method(CS)and microwave sintering(MS).The presence of single phase has been confirmed by X-ray diffraction and scanning electron microscopy of NBT ceramic.The later technique(MS)resulted in material with high density,dielectric properties and improved microstructure.The transition temperature was observed slightly higher for microwave sintered(MS)material.Longitudinal modulus measurements are very sensitive property to identify the phase transitions in ceramics.Longitudinal modulus(L)measurements were also employed on these samples in the frequency 136 kHz and can be studied in the wide temperature range 30℃to 400℃.The elastic behavior(L)showed a break at two temperatures(~200℃and 350℃)in both the conventional and microwave sintered ceramics.In NBT ceramics,permittivity anomalies are connected to modulus anomalies.The results are correlated with the dielectric measurements.This behavior explained in the light of structural phase transitions in the ferroelectric ceramics.展开更多
The xNi_(0.83)Co_(0.15)Cu_(0.02)Fe_(1.9)O_(4-δ)+PbZr_(0.52)Ti_(0.48)O_(3)(PZT)particulate magneto ferroelectric composites with x=0,0.1,0.2,0.3,0.4,0.5 and 0.6 mole fraction were prepared by conventional ceramic doub...The xNi_(0.83)Co_(0.15)Cu_(0.02)Fe_(1.9)O_(4-δ)+PbZr_(0.52)Ti_(0.48)O_(3)(PZT)particulate magneto ferroelectric composites with x=0,0.1,0.2,0.3,0.4,0.5 and 0.6 mole fraction were prepared by conventional ceramic double sintering method.The presence of two phases(perovskite structure of ferroelectric phase and spinal structure of ferromagnetic phase)was confirmed by X-ray diffraction.The magnetoelectric(ME)property of the particulate composites was determined at room temperature as a function of intensity of magnetic field.The temperature variation of the longitudinal modulus(L)and the internal friction(Q−1)of these particulate composites at 104.3 kHz was studied in the wide temperature range 30-420℃.The temperature variation of the longitudinal modulus in each composition of these particulate composites showed two abrupt minima.One minimum coincided with the ferroelectric-paraelectric Curie transition temperature(θE)and the other with the ferromagnetic-paramagnetic Curie transition temperature(θM).The internal friction measurement also showed two sharp peaks in each composition corresponding to those temperatures where the minima were noticed in the temperature variation of the longitudinal modulus behaviour.展开更多
文摘Dielectric studies were carried out on a lead free Sodium Bismuth Titanate,NBT,(Na_(0.5)Bi_(0.5)TiO_(3))composition.The material was synthesized by conventional ceramic method(CS)and microwave sintering(MS).The presence of single phase has been confirmed by X-ray diffraction and scanning electron microscopy of NBT ceramic.The later technique(MS)resulted in material with high density,dielectric properties and improved microstructure.The transition temperature was observed slightly higher for microwave sintered(MS)material.Longitudinal modulus measurements are very sensitive property to identify the phase transitions in ceramics.Longitudinal modulus(L)measurements were also employed on these samples in the frequency 136 kHz and can be studied in the wide temperature range 30℃to 400℃.The elastic behavior(L)showed a break at two temperatures(~200℃and 350℃)in both the conventional and microwave sintered ceramics.In NBT ceramics,permittivity anomalies are connected to modulus anomalies.The results are correlated with the dielectric measurements.This behavior explained in the light of structural phase transitions in the ferroelectric ceramics.
文摘The xNi_(0.83)Co_(0.15)Cu_(0.02)Fe_(1.9)O_(4-δ)+PbZr_(0.52)Ti_(0.48)O_(3)(PZT)particulate magneto ferroelectric composites with x=0,0.1,0.2,0.3,0.4,0.5 and 0.6 mole fraction were prepared by conventional ceramic double sintering method.The presence of two phases(perovskite structure of ferroelectric phase and spinal structure of ferromagnetic phase)was confirmed by X-ray diffraction.The magnetoelectric(ME)property of the particulate composites was determined at room temperature as a function of intensity of magnetic field.The temperature variation of the longitudinal modulus(L)and the internal friction(Q−1)of these particulate composites at 104.3 kHz was studied in the wide temperature range 30-420℃.The temperature variation of the longitudinal modulus in each composition of these particulate composites showed two abrupt minima.One minimum coincided with the ferroelectric-paraelectric Curie transition temperature(θE)and the other with the ferromagnetic-paramagnetic Curie transition temperature(θM).The internal friction measurement also showed two sharp peaks in each composition corresponding to those temperatures where the minima were noticed in the temperature variation of the longitudinal modulus behaviour.
