The compounds based on calcium molybdate (CaMoO 4 ) are the subject of extensive research due to their excellent optical properties and a broad range of potential technological applications. In this work, we report a systematic study of CaMoO 4 :Tm 3+ phosphors synthesized by coprecipitation and processed in a microwave-hydrothermal system at low temperature (100°C) and stirring. The effect of the Tm 3+ doping content (0%-12%) is studied in full detail to understand their role in the CaMoO 4 :Tm 3+ morphological, structural, and luminescent properties. The X-ray diffraction, Raman, and Fourier Transform Infrared spectroscopic techniques revealed that all the prepared powders have a tetragonal crystal structure with a distinct density of cation vacancies and structural disorders. The band gap remains almost constant for doping levels lower than 8%, but it narrows strongly for powders doped with 12% Tm 3+ ions.The designed phosphors have shown two emission bands in which intensity depends on the Tm 3+ ions doping level. For doping levels lower than 2%, the photoluminescence profile displays a broad emission band peaking at 543 nm (green). For concentrations higher than 4%, the band centered at 543 nm decreases in intensity and the near-infrared emission band at around 800 nm, assigned to 3 F 3 , 3 H 4 → 3 H 6 transitions from Tm 3+ ion, become more intense. The outcomes of this work reveal that appropriated Tm 3+ ions doping levels can be applied to suppress the PL emission in the visible range and improve that in the near-infrared region in CaMoO 4 -based materials. K E Y W O R D Sceramic matrix composites, microwaves, optical materials/properties, photoluminescence, rare earths How to cite this article: Feldhaus CMS, Künzel R, Li MS, Marques APdA. The role of the Tm 3+ concentration on CaMoO 4 properties processed by microwave hydrothermal under stirring condition.

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