Effects of compositional changes on up-conversion photoluminescence and electrical properties of lead-free Er-doped K0.5Na0.5NbO3-SrTiO3 transparent ceramics

Abstract

Er-doped K0.5Na0.5NbO3-SrTiO3 transparent ceramics were fabricated by traditional pressureless sintering. The dual effects of Er3+ and SrTiO3 contents on the microstructures, optical transparencies and optoelectronic properties of the ceramics were investigated. The introduction of Er3+ and Sr2+ results in decreasing grain size and generating cation vacancies, affecting the density and uniformity of the ceramics. The ceramics exhibit superior transmittance: T ∼55% in the visible region (760 nm) and ∼75% in the infrared region (2000 nm), which is dependent on optical band gap energy. In terms of electrical properties, the ceramics also possess relaxor-like characteristics, low dielectric loss and suitable piezoelectric constants. Due to Er3+, the ceramics exhibit composition-tunable green and red up-conversion photoluminescence emissions, whose intensities are related to the crystal symmetry. Combined with good optical and electrical properties, the ceramics open up potential applications in the electrical/optical interdisciplinary field, such as visible displays, solid-state lasers and transparent electronic devices.