M. G. Zuev

Sol-gel synthesis and spectral characteristics of crystal phosphors Sr2Y8(1 − x)Eu8xSi6O26

Solid solutions of the compositions Sr2Y8(1 − x)Eu8xSi6O26 (x = 0.005, 0.01, 0.03, 0.05, 0.1, 0.2, 0.4) based on silicates with the oxyapatite structure have been synthesized using the sol-gel method. The samples have been characterized using X-ray diffraction and energy dispersive X-ray analyses. The morphology of the synthesized solid solutions has been examined. The spectral-luminescent characteristics of crystal phosphors have been investigated.

MVO4-Ta2O5-Nb2O5 (M = Y, La) solid solutions

The subsolidus phase relations in the MVO4-Ta2O5-Nb2O5 (M = Y, La) systems were studied. MNb2-2xTa2xVO9 (I) and MTa2-2xNb2xVO9 (II) solid solutions were prepared and characterized by x-ray diffraction, vibrational spectroscopy, and electron spin resonance. The range of solid solutions in I isx = 0–0.58 for M = Y and 0–0.4 for M = La; in II,x = 0–0.09 for M = Y and 0–0.1 for M = La. All of the solid solutions were found to contain V(IV) centers whose nearest neighbor environment depended on composition. The structure of LaTa2-2xNb2xVO9 was shown to contain fragments characteristic of LaNb2VO9. The lattice parameters of these solid solutions correlate with the V(IV) content.

Structure and properties of glasses in the MgSO4-Na2B4O7-KPO3 system

A glass formation region has been established in the MgSO4-Na2B4O7-KPO3 system. This region is located in the borate-phosphate part of the concentration triangle and occupies ∼40% of the triangle area. Based on the spectral data obtained (nuclear magnetic resonance, IR and Raman spectroscopy), a model is proposed in terms of which the physicochemical properties (such as the linear thermal expansion coefficient, the softening temperature, and the glass transition temperature) of the samples are discussed.

Glass formation and vibrational spectra of glasses in the RSO4-Na2B4O7-K2SO4 (R = Mg, Ca, Sr, Ba) systems

The regions of glass formation in the RSO4-Na2B4O7-K2SO4 (R = Mg, Ca, Sr, Ba) systems are determined. These regions are completely concentrated in the borate-rich region of the concentration triangle and occupy approximately 20% of the triangle area. The IR and Raman spectra of the glasses under investigation are recorded. It is revealed that the vibrational spectra of the glasses depend on the type of alkaline-earth metal cation. It is assumed that the structure of the glasses is determined by the glass-forming borate motifs with embedded sulfate anion tetrahedra.

Oxidation State of Vanadium in Eu1 – xYxVTa2O9 Solid Solutions

The magnetic susceptibility of Eu1 – xYxVTa2O9 (0 < x < 0.20) solid solutions was found to vary nonmonotonically with Y content. This result was interpreted as due to changes in the proportion of V4+ ions. Increasing the synthesis temperature from 1100 to 1300°C was shown to raise the proportion of V4+ in EuVTa2O9 from 9.87 to 12.03%. The highest light yield was observed at x ≃0.05, corresponding to the smallest V4+/V5+ ratio.