Photoluminescence and energy transfer in Tb3+-doped CeO2–Mn3O4 phosphor prepared by co-precipitation method

Terbium-doped CeO 2 –Mn 3 O 4 (CMO-Tb) phosphor was synthesized using co-precipitation and calcined at 500 °C. The material was characterized by X-ray diffraction (XRD), diffuse reflectance (DR), and photoluminescence (PL) spectroscopies. XRD analysis revealed that the main peaks are assigned to cubic CeO 2 and orthorhombic Mn 3 O 4 structures, indicating a relative degree of crystallinity resulting from different nucleation processes during calcination at 500 °C. The DR analysis reveals two absorption edges at approximately 2.8 and 3.7 eV, associated with Mn 3 O 4 and CeO 2 phases, respectively, emphasizing the biphasic nature of the system. Under UV-excitation of Ce 3+ ions at 285 nm, the blue Ce 3+ luminescence at around 400 nm (i.e., the 5 d → 4 f transition) was observed and accompanied by multivisible down-conversion (DC) luminescence of Tb 3+ ions ( 5 D 4 → 7 F J ; J = 3, 4, 5, and 6 electronic transitions) due to an efficient energy-transfer (ET) mechanism from Ce 3+ sensitizer ions to Tb 3+ activator ions. This finding demonstrates the potential of CeO 2 –Mn 3 O 4 mixed oxide systems as tunable platforms for light-converting applications.