Eu2+ luminescence in Ca3Si2O7 and spectral widening and tuning of Eu2+ emission color (orangish-red to green) by crystal chemical substitution

Abstract

A series of novel yellowish-orange emitting phosphors [Ca_3−xM_xSi₂O₇ (M = Eu²⁺)] have been synthesized by high temperature solid state reaction. The powder X-ray diffraction patterns reveals a single phase formation with excellent crystalline nature of the phases. Photoluminescence excitation and emission studies show that the Eu²⁺ doped phosphors show broad absorption (300–525 nm) and emits yellowish-orange-red spectral region. Further efforts have been made to tune the Eu²⁺ emission by crystal chemical isovalent substitution of Mg²⁺ in Ca²⁺ site. Compositionally induced phase transformation has been observed at y ≥ 0.25 in Ca_2.985−yMg_yEu_0.015Si₂O₇. The yellowish-orange-red emission (y = 0) tuned to green color (y = 1) and the corresponding Commission Internationale de I'Eclairage (CIE) color coordinates (x, y) are changed from (0.5647, 0.4202) to (0.3540, 0.5932).