The La1 − x Ca x VO4 and La1 − x − y Eu y Ca x VO4 (0 ≤ x, y ≤ 0.2) micro/nanosized powders were prepared by aqueous nitrate–citrate sol–gel synthesis. Phase composition of the sample depends on the x and y values. The La0.9Ca0.1VO4 is crystallized in monoclinic structure up to the x = 0.1. The La0.9Eu0.05Ca0.05VO4 sample was also attributed to the monoclinic structure. Increasing concentration of europium and calcium ions in La1 − x − yEu y Ca x VO4 solid solutions leads to the change of the crystal structure, and subsequently, stabilization of the tetragonal phase takes place. The obtained samples were characterized by XRD analysis, SEM microscopy, and IR spectroscopy. Luminescence properties of the synthesized powders were studied. Emission of the La1 − x Ca x VO4 samples is weak and consists of wide bands in the 450–800 nm spectral range. The observed bands at 570 and 630 were ascribed to electron transitions in the distorted VO4 3− vanadate groups. Emission of the La1 − x − y Eu y Ca x VO4 samples consists of narrow spectral lines in the 550–730 nm spectral range. The lines are caused by the 5D0 → 7FJ electron transitions in the Eu3+ ions. The Ca2+ ions incorporation increases the intensity of the Eu3+ ions luminescence. Structure of the spectra depends on Ca2+ concentration and excitation wave length. The carried out analysis has revealed that Eu3+ ions form at least two different types of emission centers in the La1 − x − y Eu y Ca x VO4 samples. The assumption is made that type I centers are formed by the Eu3+ ions in their regular positions in the crystal lattice, while the type II centers have complex structure and consist of Eu3+ ions, Ca2+ cations, and oxygen vacancies.

Density functional theory (DFT) computations of the electronic structures of undoped, B- and N-doped CNT(3,3), CNT(5,5) carbon nanotubes, and graphene with adsorbed chromate anions CrO4 2− were performed within molecular cluster approach. Relaxed geometries, binding energies, charge differences of the adsorbed CrO4 2− anions, and electronic wave function contour plots were calculated using B3LYP hybrid exchange-correlation functional. Oscillator strengths of electronic transitions of CrO4 2− anions adsorbed on the surfaces of studied carbon nanostructures were calculated by the TD-DFT method. Calculations reveal covalent bonding between the anion and the adsorbents in all studied adsorption configurations. For all studied types of adsorbent structures, doping with N strengthens chemical bonding with CrO4 2− anions, providing a ~2-eV increase in binding energies comparatively to adsorption of the anion on undoped adsorbents. Additional electronic transitions of CrO4 2− anions appear in the orange-green spectral region when the anions are adsorbed on the N-doped low-diameter carbon nanotubes CNT(3,3) and CNT(5,5).

The set of composite materials that consist of micro/nanocellulose and complex K2Eu(MoO4)(PO4) luminescent oxide particles was prepared. The composites were studied by means of scanning electron microscopy, XRD analysis, dilatometry, differential scanning calorimetry and thermogravimetric analysis, and dielectric and luminescence spectroscopy. Dependencies of density, crystallinity, relative extension, thermal extension coefficient, dielectric relaxation parameters, intensity and shape of photoluminescence bands on temperature, and content of oxide component were studied. The structure of the composite without oxide is formed by grains of nearly 5–50 μm in size (crystallinity is about ~56%). Structure of the micro/nanocellulose samples which contain oxide particles is similar, but the cellulose grains are deformed by oxide particles. Dependencies of the abovementioned properties on temperature and oxide content were analyzed together with data on the size distribution of oxide particles for the samples for various oxide and molecules of water concentrations.

Morphology and photoluminescence (PL) properties for microcrystalline cellulose (MCC), microcrystalline nitrite powders of common formulae MNO₂ (M = Na, K) (MCN) and two-component materials composed of both MCC and MCN have been prepared and characterized by means of optical microscopy and luminescence spectroscopy. This study aimed to clarify a possibility of low-limit determination of the nitrite traces in water solutions by luminescent method.