Influence of synthesis time on the structural, vibrational, and optical properties of La2(MoO4)3 and Pr2(MoO4)3 synthesized via the microwave-assisted hydrothermal method

The photoluminescent properties of rare-earth molybdate compounds have attracted significant interest due to their potential application in light-emitting devices. In this work, La 2 (MoO 4 ) 3 and Pr 2 (MoO 4 ) 3 compounds were synthesized via the microwave-assisted hydrothermal (MAH) method at 150 °C using reaction times of 15, 30, and 60 min. X-ray diffraction analysis confirmed the formation of a tetragonal scheelite-type structure without detectable secondary phases. Field-emission scanning electron microscopy revealed time-dependent morphological evolution under MAH conditions. The optical bandgap values ranged from 3.70 eV to 4.03 eV for La 2 (MoO 4 ) 3 and 3.77 eV to 3.89 eV for Pr 2 (MoO 4 ) 3 . Photoluminescence measurements indicated that samples synthesized for 15 min exhibit emission in the white-light region, spanning from yellowish white to cool white, including neutral and warm white tones. These results demonstrate the potential of MAH-synthesized La 2 (MoO 4 ) 3 and Pr 2 (MoO 4 ) 3 compounds for white-light-emitting applications.