Structural, luminescence and EPR properties of deep red emitting MgY2Al4SiO12:Cr3+ garnet phosphor

MgY2-xAl4SiO12:xCr3+ garnet phosphors doped with different concentrations of Cr3+ (0.01–0.07 mol) were prepared using the sol-gel method, and their structural, luminescent, and electron paramagnetic resonance (EPR) properties were studied. Structural and morphological measurements were made by powder X-ray diffraction and scanning electron microscope, respectively. Cubic-structured garnet phosphors were observed. The diffuse reflectance spectrum of 0.02 mol Cr3+ doped MgY2Al4SiO12 phosphor was studied to estimate the crystal field parameters (Dq and B). The emission spectrum depicts intense emission in the far-red region under 580 nm excitation. The optimized concentration of Cr3+ ions is identified as 0.02 mol, for which the emission intensity is maximum. The CIE coordinates measured from the emission spectra for the as-prepared phosphors fall in the red region of the visible spectrum. The EPR spectra recorded at room temperature reveal five g-values at ~3.90, ~3.57, ~2.67, ~2.46, and ~1.97, corresponding to isolated Cr3+ ions and exchange-coupled Cr3+-Cr3+ pairs.