Rare-Earth-Doped Barium Molybdate Up-Conversion Phosphor with Potential Application in Optical Temperature Sensing

Current optical temperature sensing methods often rely on materials with limited thermal stability or insufficient luminescent response. While traditional phosphors have been widely studied, their performance under elevated temperatures remains a challenge. Researchers have explored rare-earth-doped materials for their potential in up-conversion luminescence. However, the precise impact of rare-earth ion doping on crystal structure and thermal behavior remains unclear. Existing studies have shown that up-conversion phosphors can emit visible light when excited with near-infrared lasers. Yet, the relationship between crystal lattice modifications and luminescent response has not been fully characterized. This gap motivated the investigation of BaMoO4 doped with Er3+ and Yb3+ ions. The goal was to assess how rare-earth doping affects structural and optical properties. This paper's contribution lies in linking structural changes to optical performance in a novel phosphor system.

The study aimed to synthesize and characterize a BaMoO4 phosphor doped with Er3+ and Yb3+ ions for optical temperature sensing. The researchers sought to determine how rare-earth ion doping influences crystal structure and luminescent behavior. They focused on the relationship between structural modifications and optical response. The phosphor was prepared using co-precipitation and calcination methods. The team examined the phosphor's structural and optical properties under varying conditions. They tested the material's potential for thermal sensing through luminescence quenching. The study's specific problem was to evaluate the feasibility of using this phosphor in optical temperature sensors. The motivation was to develop a material with stable and measurable luminescence under temperature changes.

The researchers synthesized the phosphor using co-precipitation and calcination at 800 °C. They analyzed the crystal structure using X-ray diffraction (XRD). Raman spectroscopy was used to study lattice modifications caused by rare-earth doping. The phosphor's optical properties were evaluated under 980 nm laser excitation. Emission spectra were recorded to assess green and red light output. The team tested the material's response to varying laser power levels. They prepared the phosphor as a pellet and flexible composite for practical applications. Thermal quenching was assessed by measuring luminescence at different temperatures.

The synthesized phosphor exhibited a tetragonal structure with a dominant (112) peak in XRD analysis. Rare-earth doping caused lattice shifts and reduced the lattice constant. Raman signal positions also changed due to the presence of Er3+ and Yb3+ ions. The phosphor emitted strong green signals at 530 and 553 nm when excited at 980 nm. Weak red emission was observed at 657 nm under the same excitation. Green emission intensity increased with higher pump power due to a two-photon effect. The material was processed into a pellet and flexible composite for practical use. Thermal quenching reduced luminescence as temperature increased, indicating potential for optical temperature sensing.

The authors found that rare-earth doping altered the crystal structure and optical response of BaMoO4. The phosphor's green emission increased with laser power, suggesting a two-photon mechanism. Thermal quenching effects were observed, supporting its use in optical temperature sensing. The material's response to temperature changes was consistent with prior research on up-conversion phosphors. The study confirmed that Er3+ and Yb3+ ions influence the crystal lattice and luminescent behavior. The phosphor's structural and optical properties were linked to its sensing potential. The results suggest that this material could serve as a thermal sensor in optical systems. The authors propose that the phosphor's response to temperature changes may be useful in practical applications.