Noncontact temperature‐dependent fluorescence depicting phase transition in Nd3+‐doped (K0.5Na0.5)NbO3 ceramics

A noncontact temperature measurement technique based on fluorescence variation was used to depict the temperature‐dependent evolution of phase transition of a ferroelectric material, that is, Nd3+‐doped (K0.5Na0.5)NbO3 ceramics. The slope of the fluorescence intensity curve changes dramatically in the two temperature regions of 450‐475 K and 650‐675 K, which correspond to orthorhombic‐tetragonal and tetragonal‐cubic transitions as confirmed by the temperature dependence of dielectric constant. Furthermore, the small deviations in δTO‐T and δTc indicate the good accuracy of this noncontact method. This work can guide other ergodic ferroelectrics to describe phase experience by the noncontact fluorescence method.