EFFECT OF MoO3 ON THE STRUCTURE AND LUMINESCENT PROPERTIES OF SODIUM PHOSPHATE-GERMANATE GLASSES CONTAINING EUROPIUM(III)

Анотація

This study investigates there gularities of obtaining phosphate-germanate glass modi­fied with molybdenum(VI) oxide, with the following composition: (45-0.5x)P₂O₅-xMoO₃-10.0GeO₂-(45-0.5x)Na₂O (x = 0.0-30.0). It was found that an increase in the concentration of MoO₃from 5 to 30 mol% leads to a reduction in the width of the forbidden band of there sulting amorphous materials, from 3.53 eV to 3.42 eV. This change is accompanied by a decrease in hygroscopicity and an enhancement in solubility with respect to Eu₂O₃ when subjected to is other maltreatment at 1000 °C for 4 hours. The effect of MoO₃ on the structure of phosphate-germanate glass has been examined for the first time. Within the molybdenum content range of 5–15 mol%, MoO3 is incorporated in to the existing polyphosphate chains, which results in structural modifications. However, when the MoO₃ content reaches 15–30 mol%, the density of the glass increases from ρ = 2.51 to 2.58 g/cm³. This change is attributed to the formation of additional chains, facilitated by the higher coordination capacity of MoO₆^6- compared to phosphate groups.  The study also demonstrated that the glass structure under goes significant changes as a result of increasing molybdenum content, which plays a keyrole in the net work formation. The method of rapid cooling of a salt melt was used to produce the phosphate-germanate glass, followed by quenching of the samples on a copper plate. The resulting glass materials were characterized by a combination of advanced techniques, including in frared (IR) and luminescence spectroscopy, diffuse reflectance spectroscopy, and X-ray powder diffraction analysis, providing comprehensive insights in to their structural and optical properties.

It has been shown that the most promising material for modeling red phosphors is the glass 39.5P₂O₅-10MoO₃-10.0GeO₂-39.5Na₂O-1Eu₂O₃, which is effectively excited by UV radiation. Among the spectral features of the obtained luminescent glass, the following characteristics should be noted: 1) In the range of 550–650 nm, it demonstrates highly intense bands of electronic transitions ⁵D₀→⁷F₁ (595 nm) and ⁵D₁→⁷F₂ (614 nm), which are characterized by significant asymmetry in structure; b) the absence of Stark splitting of the corresponding electronic transitions in the range of 550–750 nm confirms the amorphous nature of phosphate-germanate systems. The emission maximum of the obtained glass lies in the range of 615 nm, indicating the potential application of the obtained glasses in red phosphors.