Noncontact temperature‐dependent fluorescence depicting phase transition in Nd³⁺‐doped (K_0.5Na_0.5)NbO₃ ceramics

Abstract

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.

Phase transition monitoring and temperature sensing via FIR technology in Bi/Sm‐codoped KNN transparent ceramics

“…[17][18][19] Normally, contact measuring method (i.e., temperature dependence of dielectric constant) is implemented to detect phase transitions in ferroelectrics, but the samples need to be coated with metal electrode and tested by a sophisticated impedance analyzer. 20,21 In contrast, the noncontact phase transition monitoring route via simple FIR technology does not take abundant plentiful time nor bring possible damage to samples, and is advantageous to monitor the specific temperatures of phase transformations (e.g., orthorhombic-tetragonal phase transition temperature T O-T or Curie temperature T c ) in rare-earth ion (RE 3+ ) doped luminescent-ferroelectrics. 22,23 It is generally appreciated that selecting a befitting luminescent host with low phonon energy is more conducive to obtaining efficient photoluminescence (PL) properties of RE 3+ in RE 3+ doped materials.…”

“…In addition to temperature monitoring, FIR can also be applied as a noncontact characterization method to explore the phase transitions in ferroelectric materials, which arouses the curiosity of many researchers 17–19 . Normally, contact measuring method (i.e., temperature dependence of dielectric constant) is implemented to detect phase transitions in ferroelectrics, but the samples need to be coated with metal electrode and tested by a sophisticated impedance analyzer 20,21 . In contrast, the noncontact phase transition monitoring route via simple FIR technology does not take abundant plentiful time nor bring possible damage to samples, and is advantageous to monitor the specific temperatures of phase transformations (e.g., orthorhombic‐tetragonal phase transition temperature T O‐T or Curie temperature T c ) in rare‐earth ion (RE 3+ ) doped luminescent‐ferroelectrics 22,23 …”