Preparation Of Barium Strontium Titanate Based Ceramics With Pechini Method And Investigation On Electrical And Energy Storage Properties

Barium strontium titanate based piezoelectric ceramics are widely used in microelectronic devices for their low dielectric loss,excellent ferroelectric,piezoelectric,voltage resistance and insulation properties.In this paper,powders and ceramics were prepared by Pechini sol-gel method combined with solid state sintering method.The main contents of the study are as follows:?1?The gel was calcined at different temperatures to determine the optimum temperature for black aggregates and nano-powders.At the same time,the effects of sol's pH on the electrical properties and morphology of ceramic samples were systematically discussed.The impacts of sintering temperature,the dopant of Sr²⁺on the electrical properties,and the influence factor of different polarization voltages on electrical and energy storage properties of BST piezoelectric ceramics were also studied.?2?The influence mechanisms of microstructure,phase structure,electrical properties,and energy storage properties of binary system BST-BNT piezoelectric ceramics were studied.?3?Ternary composite insulating oxides CuO-B₂O₃-ZnO were doped in BST-BNT ceramics.The effects of different dopant on the morphology,phase structure,electrical and energy storage properties of piezoelectric ceramics were studied systematically.?4?The effects of rare earth oxide Sm₂O₃ and insulating oxide MgO were co-doped in BST-BNT.The morphology,phase structure,electrical properties,and energy storage properties of piezoelectric ceramics with different doping amount were studied.The optimal calcination temperatures of black coking powder and nano powder were set as 440? and 800?,respectively.When pH=5,the best electrical performance of BST ceramics was obtained,i.e.,?_r=8114,T_C=59?,d₃₃=78 pC/N,k_p=14.96%,and Q_m=85.When the sintering temperature is 1220?,not only stable dielectric and piezoelectric properties are obtained,but also high mechanical quality factor are further achieved(?_r=4264,T_C=63?,d₃₃=87 pC/N,k_p=13.89%,and Q_m=89).When the ratio of Sr in Ba_?1-x?Sr_xTiO₃ ceramics x=0.04,the piezoelectric performance was greatly improved,but the mechanical quality factor needed to be improved urgently(?_r = 4626,T_C = 92 ?,d₃₃ = 172 p C/N,k_p = 22.40%,and Q_m = 10).Which polarized at 4 kV,high ferroelectric and energy storage properties of Ba_?1-x?Sr_xTiO₃ ceramics were achieved:P_s=10.95?C/cm²,E_c=2.30 kV/cm,P_r=2.43?C/cm²,J_r=0.06 J/cm³,and?=49.2%.The most excellent electrical and storage properties of?1-x?BST-xBNT?x=0.35?piezoelectric ceramics were obtained:?_r=2812,T_C=183?,P_s=12.62?C/cm²,E_c=5.67 kV/cm,P_r=1.39?C/cm²,J_r=0.040J/cm³,and?=51.9%.BST-yCBZ?y=0.15wt%?ceramics,which were sintered at 1190?,has the optimal dielectric,piezoelectric and mechanical quality factor,as well as relatively good temperature stability of dielectric property:?_r=6114,T_C=102?,d₃₃=75 pC/N,k_p=8.79%,and Q_m=248.Because of stable pure perovskite structure and smallest grain size,the optimal electrical properties of CuO-B₂O₃-ZnO doped in BST-BNT-yCBZ?y=0.10wt%?were obtained:?_r=2199,T_C=147?,d₃₃=23 pC/N,P_r=3.16?C/cm²,E_c=9.62 kV/cm,J_r=0.05 J/cm³,and ?=29.8%;BST-BNT-z SM?z=0.05 wt%?ceramics doped by Sm₂O₃ and MgO were prepared at 1130? with tetragonal phase,perovskite structure and optimal electrical and energy storage properties:?_r=2345,T_C=150?,J_r=0.04 J/cm³,and?=52%.However Sm₂O₃-MgO generated at high temperature of glass phase lead to deteriorate piezoelectric property(d₃₃=13 pC/N).The research results in thesis showed that the doping modification of BST-based piezoelectric ceramics increases the Curie temperature.That lead them to work stably at an ambient temperature nearly 100 ?.BST-BNT-yCBZ piezoelectric ceramics with excellent ferroelectric and energy storage properties can be used to construct solid-state memory.BST-based piezoelectric ceramics with low electromechanical coupling coefficient can be used in narrow-band filters.It is of great significance to realize the goal of substitution of lead-based piezoelectric materials by lead-free piezoelectric materials.