The role of the Tm3+ concentration on CaMoO4 properties processed by microwave hydrothermal under stirring condition |
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Authors: | Carla Marina Santos Feldhaus Roseli Künzel Máximo Siu Li Ana Paula de Azevedo Marques |
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Affiliation: | 1. Laboratório de Materiais Inorgânicos e Nanoestruturados (LAMIN), Departamento de Química, Universidade Federal de São Paulo - UNIFESP, Diadema, Brasil;2. Departamento de Física, Universidade Federal de São Paulo - UNIFESP, Diadema, Brasil;3. Instituto de Física de São Carlos, Universidade de São Paulo - USP, São Carlos, Brasil |
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Abstract: | The compounds based on calcium molybdate (CaMoO4) 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 CaMoO4:Tm3+ phosphors synthesized by coprecipitation and processed in a microwave-hydrothermal system at low temperature (100°C) and stirring. The effect of the Tm3+ doping content (0%–12%) is studied in full detail to understand their role in the CaMoO4:Tm3+ 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% Tm3+ ions. The designed phosphors have shown two emission bands in which intensity depends on the Tm3+ 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 3F3, 3H4 → 3H6 transitions from Tm3+ ion, become more intense. The outcomes of this work reveal that appropriated Tm3+ ions doping levels can be applied to suppress the PL emission in the visible range and improve that in the near-infrared region in CaMoO4-based materials. |
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Keywords: | ceramic matrix composites microwaves optical materials/properties photoluminescence rare earths |
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