Enhancement of energy storage and pyroelectric properties of (Na_0.5Bi_0.5)TiO₃-SrTiO₃-BaTiO₃ ceramics by addition of (Ba_0.9B_0.1)TiO₃ glass-phase

Abstract

The present study introduces a novel study of the effect of the glass phase on the energy storage and the pyroelectric properties of 0.65(Bi0.5Na0.5)TiO3-0.25SrTiO3–0.1BaTiO3 (abbreviate NBT-ST-BT) lead-free ceramics. The glass phase was prepared by melt-quenching of (Ba0.9B0.1)TiO3 (BBT) calcined powder. Different content of BBT glass phase was introduced into the ceramic matrix [(1-x)(NBT-ST-BT) – x(BBT)] (x = 0.0, 2.5, 5, 7.5 and 10%) solid solution. The crystal structure shows rhombohedral and orthorhombic coexistence phases with increasing the volume fraction of the R-phase by increasing BBT glass content. The grain size was suppressed to a sub-micrometer by increasing the BBT glass amount, denoting the enhanced dielectric breakdown strength (BDS). The largest recoverable energy storage density (Wrec = 2.5 J/cm3) with the highest energy storage efficiency (ƞ ~ 87%) has been obtained at 200kV/cm of BBT 5%. The variation in Wrec of the optimum sample is less than 4% from 25oC to 150oC, indicating the high thermal stability of energy storage properties. The pyroelectric coefficient (PE) was estimated by an approximate numerical method by differentiating remnant polarization Pr concerning temperature. The pyroelectric properties and figure of merit (FOM) were enhanced by the addition of the BBT glass phase. The FOM increased from 7 x 10-10 to 8 x 10-10 C/cm2.oC at T=150oC when glass content increased from 0.0 to 0.1. These results prove that the addition of the BBT glass phase resolves the contrary between high energy storage properties and lower sintering temperatures of ceramic materials in addition to enhancing the pyroelectric properties for practical applications.