Ho³⁺‐doped (K, Na)NbO₃‐based multifunctional transparent ceramics with superior optical temperature sensing performance

Ho 3+ ‐doped (K 0.5 Na 0.5 )NbO 3 ‐based transparent ceramics have been prepared via pressureless solid‐state method. The ceramics possess moderate optical transparency with the energy band gap of ~2.9 eV and submicron‐sized grains (<500 nm). The temperature‐dependent dielectric properties and ferroelectric polarization‐electric field hysteresis loops demonstrate that the ceramics own relaxor‐like characteristics. The up‐conversion...