Large electrostrictive effect and high optical temperature sensitivity in Er³⁺-modified (K_0.5Na_0.5)NbO₃-based ferroelectric ceramics

With the rapid development of optoelectronic technology, the realization of multi-functional properties of ferroelectrics has recently become a hot research topic. In the present study, a high electrostrictive effect and excellent photoluminescence properties have been achieved by introducing rare earth Er3+ ions into the high-performance 0.96(K0.48Na0.52)(Nb0.95Sb0.05)O-3-0.04Bi(0.5)(Na0.82K0.18)(0.5)ZrO3 (0.96KNNS-0.04BNKZ) ferroelectric ceramic. As a result of the Er3+ doping, the ferroelectric long-range order of 0.96KNNS-0.04BNKZ was disrupted, which led to the formation of polar nanoregions and electrostriction enhancement. The sample that was doped with 0.8 mol% Er3+ ions showed a high electrostrictive strain of similar to 0.11 % (at 80 kV/cm), with a large electrostrictive coefficient, Q(33,) of 0.033 m(4)/C-2. Q(33) was not sensitive to either a temperature change or field cycling. In addition, the Er3+-modified samples showed a bright up-conversion photoluminescence with a strong green emission, which could be explained by the presence of Er3+ activator ions. Furthermore, an excellent optical temperature performance, with a sensitivity of S = 0.0075 K-1 at 570 K, was achieved for the ceramic that was doped with 0.1 mol% Er3+. This sensitivity was higher than for most rare earth-doped ferroelectric materials. Because of these excellent optical and electrical characteristics, the Er3+-doped 0.96KNNS-0.04BNKZ-based ferroelectrics demonstrated promising prospects for applications in optical-electrically integrated and coupling devices.