EPR and optical investigations of LaMgAl11O19:Cr3+ phosphor

The LaMgAl11O19:Cr3+ phosphor has been prepared by a low-temperature combustion synthesis method. As-prepared combustion synthesized powder was characterized using powder X-ray diffraction (XRD), diffuse reflectance (DRS), electron paramagnetic resonance (EPR) and photoluminescence (PL) studies. The X-ray diffraction pattern reveals crystalline hexagonal phases. The UV–vis diffuse reflectance spectrum exhibits three broad bands characteristic of Cr3+ ions in octahedral symmetry. The EPR spectrum exhibits several resonance signals. The signals with the effective g values at g = 4.84, 3.64 and 2.26 have been attributed to the isolated Cr3+ ions. The signal with the effective g value at g = 1.94 has been attributed to exchange coupled Cr3+–Cr3+ ion pairs. The PL studies exhibit several bands characteristic of Cr3+ ions in octahedral symmetry.