Recent years,the polarization response of ferroelectrics has been entirely studied.However,it is found that the polarization may disappear gradually with the continually applied of electric field.In this paper,taking ...Recent years,the polarization response of ferroelectrics has been entirely studied.However,it is found that the polarization may disappear gradually with the continually applied of electric field.In this paper,taking K0.48Na0.52NbO3(KNN)as an example,it was demonstrated that the residual polarization began to decrease when the electric field frequency increased to a certain extent using a phase-field methods.The results showed that the content of out-of-plane domains increased first and then decreased with the increase of applied electric field frequency,the maximum polarization disappeared at high frequencies,and the hysteresis loop became elliptical.In order to further study the abnormal changes of hysteresis loops of ferroelectrics under high electric field frequency,we analyzed the hysteresis loop and dielectric response of solid solution 0.1SrTiO_(3)-0.9K_(0.48)Na_(0.52)NbO_(3).It was found that the doped hysteresis loop maintained its shape at higher frequency and the dielectric constant increased.This kind of doping has a higher field frequency adaptability,which has a key guiding role in improving the dielectric properties of ferroelectric thin films and expanding the frequency application range of ferroelectric nano memory。展开更多
The modified BaTiO3 ferroelectric materials are suitable for pyroelectric applications. This paper reports the structural, dielectric and electrical properties on copper influence in BaTiO3 when it was substituted si...The modified BaTiO3 ferroelectric materials are suitable for pyroelectric applications. This paper reports the structural, dielectric and electrical properties on copper influence in BaTiO3 when it was substituted site “A” of perovskite structure of BaTiO3. Copper has been chosen for modified BaTiO3 with different concentrations with stoichiometry Ba1-xCuxTiO3, where x = 0.01%, 0.02%, 0.03% and 0.04%. The X-ray diffraction patterns of the samples doped with different composition of CuO are found to be that the positions and intensities of the diffraction peaks are similar and no secondary phases were observed. The Curie’s temperature (Tc) for all CuO doped BaTiO3 with were found to be in the range of 120°C to 125°C. The frequency dependence of relative permittivity (εr) and dielectric loss (Tanδ) of Ba1-xCuxTiO3 samples at room temperature were reported in the range 100 KHz - 1 MHz. The temperature dependence of D.C electrical resistivity studies were reported for all samples indicating that the participation of Cu2+-Cu+ ions in the conduction process around their Curie’s temperature.展开更多
CaCu（3-x）FexTi4O（12）（x=0, 0.015, 0.03, 0.045, 0.06） ceramics were synthesized by sol-gel method. The electrical conduction and dielectric measurements show that the doping of a very small amount of Fe（3＋） ion...CaCu（3-x）FexTi4O（12）（x=0, 0.015, 0.03, 0.045, 0.06） ceramics were synthesized by sol-gel method. The electrical conduction and dielectric measurements show that the doping of a very small amount of Fe（3＋） ions greatly reduces the low-frequency dielectric constants and leakage, and enhances grain resistivity. For the doped samples, the appearance of the strong low-frequency peaks in the spectra of dielectric loss confirms that the doping of Fe（3＋） ions induces the contact-electrode effect on ceramic surface. These great changes of electrical properties may originate from the reduced amount of oxygen vacancies by doping Fe（3＋）展开更多
基金supported by National Defense Basic Scientific Research Program of China(Grant Nos.JCKY2020408B002,WDZC2022-12).
文摘Recent years,the polarization response of ferroelectrics has been entirely studied.However,it is found that the polarization may disappear gradually with the continually applied of electric field.In this paper,taking K0.48Na0.52NbO3(KNN)as an example,it was demonstrated that the residual polarization began to decrease when the electric field frequency increased to a certain extent using a phase-field methods.The results showed that the content of out-of-plane domains increased first and then decreased with the increase of applied electric field frequency,the maximum polarization disappeared at high frequencies,and the hysteresis loop became elliptical.In order to further study the abnormal changes of hysteresis loops of ferroelectrics under high electric field frequency,we analyzed the hysteresis loop and dielectric response of solid solution 0.1SrTiO_(3)-0.9K_(0.48)Na_(0.52)NbO_(3).It was found that the doped hysteresis loop maintained its shape at higher frequency and the dielectric constant increased.This kind of doping has a higher field frequency adaptability,which has a key guiding role in improving the dielectric properties of ferroelectric thin films and expanding the frequency application range of ferroelectric nano memory。
文摘The modified BaTiO3 ferroelectric materials are suitable for pyroelectric applications. This paper reports the structural, dielectric and electrical properties on copper influence in BaTiO3 when it was substituted site “A” of perovskite structure of BaTiO3. Copper has been chosen for modified BaTiO3 with different concentrations with stoichiometry Ba1-xCuxTiO3, where x = 0.01%, 0.02%, 0.03% and 0.04%. The X-ray diffraction patterns of the samples doped with different composition of CuO are found to be that the positions and intensities of the diffraction peaks are similar and no secondary phases were observed. The Curie’s temperature (Tc) for all CuO doped BaTiO3 with were found to be in the range of 120°C to 125°C. The frequency dependence of relative permittivity (εr) and dielectric loss (Tanδ) of Ba1-xCuxTiO3 samples at room temperature were reported in the range 100 KHz - 1 MHz. The temperature dependence of D.C electrical resistivity studies were reported for all samples indicating that the participation of Cu2+-Cu+ ions in the conduction process around their Curie’s temperature.
基金support from the National Natural Science Foundation of China (Nos.51172166 and 51202078)the Huazhong University of Science and Technology, China (No. 01-18-185011)
文摘CaCu（3-x）FexTi4O（12）（x=0, 0.015, 0.03, 0.045, 0.06） ceramics were synthesized by sol-gel method. The electrical conduction and dielectric measurements show that the doping of a very small amount of Fe（3＋） ions greatly reduces the low-frequency dielectric constants and leakage, and enhances grain resistivity. For the doped samples, the appearance of the strong low-frequency peaks in the spectra of dielectric loss confirms that the doping of Fe（3＋） ions induces the contact-electrode effect on ceramic surface. These great changes of electrical properties may originate from the reduced amount of oxygen vacancies by doping Fe（3＋）
