The effect of thermal and electrical histories on structure and dielectric behaviors is studied using 0.95(Bi_(0.5)Na_(0.5))_(0.97)(Li_(0.5)Nd_(0.5))_(0.03)TiO_(3)-0.05BaTiO_(3)(abbreviated as BNTLN0.03-BT5)ceramic as...The effect of thermal and electrical histories on structure and dielectric behaviors is studied using 0.95(Bi_(0.5)Na_(0.5))_(0.97)(Li_(0.5)Nd_(0.5))_(0.03)TiO_(3)-0.05BaTiO_(3)(abbreviated as BNTLN0.03-BT5)ceramic as a selected system.Subtle structure change caused by annealing treatment,and pronounced phase transition and domain switching by electrical poling,are observed to occur,respectively.The dielectric constant and its strong frequency dispersion in unpoled samples decrease evidently by electrical poling due to electric field-induced ordered domain.The high temperature Maxwell-Wagner relaxor behavior vanishes by annealing treatment due to the loss of electrical inhomogeneity with interface charging effects.Piezoelectric properties are improved evidently by annealing treatment at 900℃,implying a new appropriate method to improve piezoelectric properties.展开更多
Microstructure and dielectric behaviors of heating/cooling and bias-field were investigated in lead-free ceramics(1-x)Bi_(0.5)Na_(0.5)TiO_(3)-xBaTiO_(3)(BNT-xBT,x=0,0.02,0.04,0.06,0.08 and 0.10).The relaxor characters...Microstructure and dielectric behaviors of heating/cooling and bias-field were investigated in lead-free ceramics(1-x)Bi_(0.5)Na_(0.5)TiO_(3)-xBaTiO_(3)(BNT-xBT,x=0,0.02,0.04,0.06,0.08 and 0.10).The relaxor characters and the Vogel–Fulcher law of frequency-dependent dielectric properties were analyzed.Three dielectric anomalies with pronounced frequency dispersion at Td,a maximum dielectric with variable frequency-dispersion at Tm and a third Maxwell–Wagner-type relaxation over a wide temperature range in high-temperature region were observed.The significant dielectric thermal hysteresis,low barrier energy,high freezing temperature in heating process and the maximum dielectric tunability appeared in x=0.4 ceramic.展开更多
The structure of the ferroelectrics has been widely studied in order to pursuing the origin of high electromechanical responses. However, some experiments on structure of ferroelectrics have yielded different results....The structure of the ferroelectrics has been widely studied in order to pursuing the origin of high electromechanical responses. However, some experiments on structure of ferroelectrics have yielded different results. Here, we report that the controversial phase structure is due to the adaptive diffraction of nanodomains which hides the natural crystal structure, and the electric-field-induced phase transition is that the natural crystal structure reappears due to the coalescent nanodomains or ordering nanodomains by applying a high electric field. The temperature dependence of dielectric constant with different measurement frequencies and X-ray diffraction (XRD) patterns of unpoled, poled, and annealing after poled ceramics in Bi0.5Na0.5TiO3–BaTiO3 (BNT–BT) ceramics authenticate the statement. These results provide a new insight into the origin of structural complexity in ferroelectric ceramics, which is related to the key role of nanodomains.展开更多
基金Part of this work was financially supported by the National Nature Science Foundation of China(11564007,61561015,and 61361007)Guangxi Key Laboratory of Information Materials(1310001-Z)the Natural Science Foundation of Guangxi(2015GXNSFAA 139250).
文摘The effect of thermal and electrical histories on structure and dielectric behaviors is studied using 0.95(Bi_(0.5)Na_(0.5))_(0.97)(Li_(0.5)Nd_(0.5))_(0.03)TiO_(3)-0.05BaTiO_(3)(abbreviated as BNTLN0.03-BT5)ceramic as a selected system.Subtle structure change caused by annealing treatment,and pronounced phase transition and domain switching by electrical poling,are observed to occur,respectively.The dielectric constant and its strong frequency dispersion in unpoled samples decrease evidently by electrical poling due to electric field-induced ordered domain.The high temperature Maxwell-Wagner relaxor behavior vanishes by annealing treatment due to the loss of electrical inhomogeneity with interface charging effects.Piezoelectric properties are improved evidently by annealing treatment at 900℃,implying a new appropriate method to improve piezoelectric properties.
基金supported by the National Nature Science Foundation of China(11564007,61561015,51862004,11664006)the Natural Science Foundation of Guangxi(2017GXNSFDA198024,2018GXNSFAA294039)。
文摘Microstructure and dielectric behaviors of heating/cooling and bias-field were investigated in lead-free ceramics(1-x)Bi_(0.5)Na_(0.5)TiO_(3)-xBaTiO_(3)(BNT-xBT,x=0,0.02,0.04,0.06,0.08 and 0.10).The relaxor characters and the Vogel–Fulcher law of frequency-dependent dielectric properties were analyzed.Three dielectric anomalies with pronounced frequency dispersion at Td,a maximum dielectric with variable frequency-dispersion at Tm and a third Maxwell–Wagner-type relaxation over a wide temperature range in high-temperature region were observed.The significant dielectric thermal hysteresis,low barrier energy,high freezing temperature in heating process and the maximum dielectric tunability appeared in x=0.4 ceramic.
基金Part of this work was financially supported by the National Natural Science Foundation of China
文摘The structure of the ferroelectrics has been widely studied in order to pursuing the origin of high electromechanical responses. However, some experiments on structure of ferroelectrics have yielded different results. Here, we report that the controversial phase structure is due to the adaptive diffraction of nanodomains which hides the natural crystal structure, and the electric-field-induced phase transition is that the natural crystal structure reappears due to the coalescent nanodomains or ordering nanodomains by applying a high electric field. The temperature dependence of dielectric constant with different measurement frequencies and X-ray diffraction (XRD) patterns of unpoled, poled, and annealing after poled ceramics in Bi0.5Na0.5TiO3–BaTiO3 (BNT–BT) ceramics authenticate the statement. These results provide a new insight into the origin of structural complexity in ferroelectric ceramics, which is related to the key role of nanodomains.
