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

Abstract

AbstractThe phase transition temperature (e.g., that of orthorhombic‐tetragonal TO‐T) of relaxor ferroelectrics are commonly obtained through electrical method (i.e., temperature dependence of dielectric constant), and the samples need to be coated with metal electrode and tested by a sophisticated impedance analyzer. This contact measuring method is inefficient, inconvenient and easy to damage the sample surface, inapplicable to transparent ferroelectrics. Here, we successfully fabricated Bi/Sm co‐doped K0.5Na0.5NbO3 transparent ceramics with photoluminescent behavior and relaxor‐like ferroelectricity, which simultaneously realized TO‐T monitoring and temperature sensing via fluorescence intensity ratio (FIR) technology. This simple, rapid, noncontact and nondestructive optical way displays small TO‐T deviation (merely 0.78%) compared to the electrical method. And the temperature‐dependent optical characteristics and coercive electric field all present abrupt changes, whose abnormal temperature regions are in accordance with that around TO‐T. In addition, the maximum absolute sensitivity and relative sensitivity of the ceramics reach 0.0072 K−1 (at 533 K) and 0.0111 K−1 (at 453 K), respectively, exhibiting superior optical temperature sensing performance. The tactical use of FIR technology is of great significance for widening the applications of luminescent‐ferroelectric transparent ceramics.