Based on the density functional theory within the local density approximation (LDA), we studied the electronic, elastic, and dynamic properties of AgNbO<sub>3</sub> and AgTaO<sub>3</sub> compou...Based on the density functional theory within the local density approximation (LDA), we studied the electronic, elastic, and dynamic properties of AgNbO<sub>3</sub> and AgTaO<sub>3</sub> compounds under pressure. The elastic constants, optic and static dielectric constants, born effective charges, and dynamic properties of AgNbO<sub>3</sub> and AgTaO<sub>3</sub> in cubic phase were studied as pressure dependences with the ab initio method. For these compounds, we have also calculated the bulk modulus, Young’s modulus, shear modulus, Vickers hardness, Poisson’s ratio, anisotropy factor, sound velocities, and Debye temperature from the obtained elastic constants. In addition, the brittleness and ductility properties of these compounds were estimated from Poisson’s ratio and Pugh’s rule (G/B). Our calculated values also show that AgNbO<sub>3</sub> (0.37) and AgTaO<sub>3</sub> (0.39) behave as ductile materials and steer away from brittleness by increasing pressure. The calculated values of Vicker hardness for both compounds indicate that they are soft materials. The results show that band gaps, elastic constants, elastic modules, and dynamic properties for both compounds are sensitive to pressure changes. We have also made some comparisons with related experimental and theoretical data that is available in the literature.展开更多
Inspired by the increasing demand for energy-storage capacitors in electrical and electronic systems, dielectrics with high energy-storage performance have attracted more and more attention. AgNbO_(3) -based lead-free...Inspired by the increasing demand for energy-storage capacitors in electrical and electronic systems, dielectrics with high energy-storage performance have attracted more and more attention. AgNbO_(3) -based lead-free ceramics serve as one of the most promising environmental-friendly candidates. However, their energy storage optimization is seriously limited by the low breakdown strength. Fortunately, thin film as a form of AgNbO3 materials can effectively improve the breakdown strength. In this work, AgNbO_(3)film with ∼550 nm in thickness was deposited on SrRuO_(3 )/(001)SrTiO_(3) using pulsed laser deposition. The AgNbO_(3) film reveals typical relaxor ferroelectric hysteresis loops due to the new nanopillar structure, which contributes to high breakdown strength of up to 1200 kV cm^(-1) . Benefiting from the high breakdown strength, a recoverable energy storage density of 10.3 J cm^(-3) and an energy efficiency of 72.2% are obtained in the AgNbO_(3) film, which demonstrates the promising prospect of AgNbO_(3) film for energy storage applications.展开更多
文摘Based on the density functional theory within the local density approximation (LDA), we studied the electronic, elastic, and dynamic properties of AgNbO<sub>3</sub> and AgTaO<sub>3</sub> compounds under pressure. The elastic constants, optic and static dielectric constants, born effective charges, and dynamic properties of AgNbO<sub>3</sub> and AgTaO<sub>3</sub> in cubic phase were studied as pressure dependences with the ab initio method. For these compounds, we have also calculated the bulk modulus, Young’s modulus, shear modulus, Vickers hardness, Poisson’s ratio, anisotropy factor, sound velocities, and Debye temperature from the obtained elastic constants. In addition, the brittleness and ductility properties of these compounds were estimated from Poisson’s ratio and Pugh’s rule (G/B). Our calculated values also show that AgNbO<sub>3</sub> (0.37) and AgTaO<sub>3</sub> (0.39) behave as ductile materials and steer away from brittleness by increasing pressure. The calculated values of Vicker hardness for both compounds indicate that they are soft materials. The results show that band gaps, elastic constants, elastic modules, and dynamic properties for both compounds are sensitive to pressure changes. We have also made some comparisons with related experimental and theoretical data that is available in the literature.
基金supported by the Natural Science Foundation of Hebei Province,China(No.E2021201044)the National Natural Science Foundation of China(Nos.51802068 and 52073144)+3 种基金the Natural Science Foundation of Jiangsu Province,China(No.BK20201301)State Key Laboratory of New Ceramic and Fine Processing Tsinghua University(No.KF202114)the Research Fund of State Key Laboratory of Mechanics and Control of Mechani-cal Structures(Nanjing University of Aeronautics and Astronautics)(No.MCMS-I-0522G02)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Inspired by the increasing demand for energy-storage capacitors in electrical and electronic systems, dielectrics with high energy-storage performance have attracted more and more attention. AgNbO_(3) -based lead-free ceramics serve as one of the most promising environmental-friendly candidates. However, their energy storage optimization is seriously limited by the low breakdown strength. Fortunately, thin film as a form of AgNbO3 materials can effectively improve the breakdown strength. In this work, AgNbO_(3)film with ∼550 nm in thickness was deposited on SrRuO_(3 )/(001)SrTiO_(3) using pulsed laser deposition. The AgNbO_(3) film reveals typical relaxor ferroelectric hysteresis loops due to the new nanopillar structure, which contributes to high breakdown strength of up to 1200 kV cm^(-1) . Benefiting from the high breakdown strength, a recoverable energy storage density of 10.3 J cm^(-3) and an energy efficiency of 72.2% are obtained in the AgNbO_(3) film, which demonstrates the promising prospect of AgNbO_(3) film for energy storage applications.
