A correlation of piezoelectricity and photoluminescence of europium doped (Na0.41K0.09Bi0.5)TiO3 with ferroelectric and structural ordering

Abstract

A correlation between piezoelectricity and photoluminescence is investigated for europium doped (Na 0.41 K 0.09 Bi 0.5 )TiO 3 ceramic. An optimum piezoelectric and dielectric response is observed for 1.0 at.% Eu doped (Na 0.41 K 0.09 Bi 0.5 )TiO 3 . For doping concentration higher than 1.0 at.% a gradual fall in the piezoelectric response is observed which is associated to the amphoteric nature of Eu 3+ ion. On the contrary, the photoluminescence intensity increases monotonically with the increase in Eu concentration. On application of an electric field, although there is no noticeable shift in the position and shape of the photoluminescence line, a quenching of hypersensitive 5 D 0 → 7 F 2 transition is observed. The quenching effect is more evident for lower doping concentration (less than 2.0 at.%) of europium. The emergence of irreversible tetragonal phase, after application of the electric field, is attributed to the quenching of 5 D 0 → 7 F 2 transition. Based on these investigations it is concluded that the piezoelectric and photo-luminescence lack one-to-one correlation. The PL response is associated to the local site symmetry around Eu 3+ and it is independent of the development of long-range ordering.