Piezoelectric Effect And Energy Storage Performance Of NBT Based Lead-free Thin Films

NBT-based lead free piezoelectric materials is very attractive, due to large electromechanical coupling coefficient, excellent ferroelectric and pyroelectric properties. Among the NBT-based solutions, NBT-xBT system has attracted much attention due to its morphotropic phase boundary between rhombohedral and tetragonal phases at x≈0.06. Considering the above,((1-x)NBT-xBT) thin films were maded by sol-gel method, the effect of the seed layer and x on the piezoelectric effect in MPB were studied, in this paper, In addition, for 0.75NBT-0.25 ST thin film, the depolarization temperature down to room temperature, relaxation ferroelectric phase and ferroelectric phase coexistence. Compared with pure NBT, the value of Pmax-Pr increased in 0.75NBT-0.25 BT thin films, which is promising to receive a larger recoverable energy density. This paper also studied the energy-storage performance of 0.94NBT-0.06 BT thin films and 0.75NBT-0.25 ST thin film.With the help of PFM and autocorrelation techniques and converse piezoelectric coefficients d33 of the((1-x)NBT-x BT) thin films are discussed and analyzed. Autocorrelation function technique applied to the analysis of the obtained PFM images revealed clear self-organization of the nanodomains and allowed estimating their mean size. The mean sizes of the domains of the 0.93NBT-0.07 BT thin films is smallest at room temperature respectively. The largest converse piezoelectric coefficient d33 is 123pm/V for NBT-0.07 BT thin films.Electric hysteresis loops under different electric fields are used to calculate energy storage properties of the 0.94NBT-0.06 BT thin films and 0.75NBT-0.25 ST thin film. The low annealing temperature and PLCT seed layer could improve the values of electric break-down field strength and Pmax-Pr. Owing to the high electric break-down field strength value of 3310 kV/cm, a large recoverable energy density of W=17.2 J/cm3 and a high energy efficiency of η=74.3 % were obtained for the 0.94BT-0.06 BT thin film with the PLCT seed layer, which was annealed at 450 ℃. The maximum W values at their corresponding BDS are 19.6 J/cm3 for the PLCT/0.75NBT-0.25 ST thin film annealed at 500 ℃.