Electrical and Luminescent Behavior of Calcium Silicate Doped with Erbium and Terbium Ions

Abstract

Calcium silicate phosphors doped with rare-earth ions exhibit remarkable luminescent and electrical properties for optoelectronic applications. This study investigates the electrical conductivity and photoluminescence characteristics of calcium silicate (Ca₂SiO₄) doped with erbium (Er³⁺) and terbium (Tb³⁺) ions at various concentrations. The synthesis was performed using solid-state reaction method at 1200°C. We hypothesized that dual doping would enhance both electrical conductivity and luminescence intensity compared to single-doped samples. Structural characterization was conducted using X-ray diffraction, while luminescent properties were analyzed through photoluminescence spectroscopy under UV excitation. Electrical measurements revealed that 2 mol% Er³⁺ and 1 mol% Tb³⁺ co-doped samples exhibited optimal conductivity of 3.8 × 10⁻⁴ S/cm at room temperature. Photoluminescence spectra showed characteristic green emission from Tb³⁺ at 544 nm and red emission from Er³⁺ at 660 nm. The energy transfer efficiency between Tb³⁺ and Er³⁺ was calculated as 42%. Results demonstrate that co-doping significantly improves material performance, suggesting potential applications in solid-state lighting, display devices, and optical sensors.