Pinched P–E hysteresis loops of KSr2Nb5O15 ferroelectric ceramics

Abstract

Pinched polarization–electric field (P–E) loop was reported in many perovskites, while it is rarely observed in tungsten bronze structures. Here, the KSr2Nb5O15 (KSN) ceramics were prepared by using the KSN calcined and microcrystalline powder as raw materials. Among them, the KSN microcrystalline were fabricated by the molten salt synthesis, which had many K+/Sr2+ vacancies. The pinched P–E hysteresis loops was found in the KSN ceramics with the larger grain size. In order to investigate the effect of K+/Sr2+ vacancies on remnant polarization, the grain-oriented KSN ceramics were prepared by using microcrystalline powder. The ferroelectric hysteresis loops were tested under different conditions. The results suggested that the electric field, temperature and frequency had a significant influence on the shape of P–E loop. The characteristic could be attributed to the pinning effect of point defects on domain wall motion.