Temperature dependent dielectric and ferroelectric properties of Sr2Na(1-x)K(x)Nb5O15 (0≤x≤0.07) Tetragonal Tungsten Bronze (TTB) ceramics

Abstract

Relaxor ferroelectric (RFE) materials show potential candidat for many everyday applications due to their stabilized crystal structure, also appealing for energy storage, and pulse power capacitors because of their highly unique characteristics. In the present work, Sr2Na(1-x)K(x)Nb5O15 (SNKN) ceramics with (x = 0.00–0.07) were synthesized using commercial grade raw materials through solid state processing technique. The effect of K+ doping in the A site on crystal structure, relaxor behavior, and energy storage characteristics was analyzed. All the compositions show P4bm space group with single phase tetragonal structure. The dielectric property reveals that all ceramics compositions have low losses (tan δ < 5 %) at RT and further losses reduce at higher temperatures. The composition with x = 0.03, the maximum permittivity achieved is (εm = 2338). Moreover, an analysis on the energy storage density and efficiency of K+ content was carried out. At an applied electric field of 40 kV/cm, SNKN ceramics with x = 0.07, energy storage density (Wrec = 0.35 J cm−3) and efficiency (η = 82 %) was optimized. The variation in Wrec from RT to 120 °C is very small and efficiency (η) was remained above 88 %. Nevertheless, the response of energy storage of these formulations is low, but they are new class of materials demonstrating better relative permittivity, lower tan δ, and temperature stability in Ferroelectricity and representing potential applications at high temperatures.