Robust and tunable ferroelectricity in Ba/Co co-doped (K0.5Na0.5)NbO3 ceramics

The 0.98(K0.5Na0.5)NbO3-0.02Ba(Nb0.5Co0.5)O3-δ ceramics with doped Ba2+ and Co2+ ions are fabricated, and the impacts of the thermal process are studied. Compared with the rapidly cooled (RC) sample, the slowly cooled (SC) sample possesses superior dielectric and ferroelectric properties, and an 11 K higher ferroelectric-paraelectric phase transition temperature, which can be attributed to the structural characteristics such as the grain size and the degree of anisotropy. Heat treatment can reversibly modulate the content of the oxygen vacancies, and in turn the ferroelectric hysteresis loops of the samples. Finally, robust and tunable ferroelectric property is achieved in SC samples with good structural integrity.