Synthesis of SrF2:Yb:Er ceramic precursor powder by co-precipitation from aqueous solution with different fluorinating media: NaF, KF and NH4F.

The major challenge in optical ceramic technology is the quality of the starting precursor powder for pressing, which is a key element in the optical ceramic industry. One express and helpful technique for the estimation of powder quality is the estimation of the quantum yield of up-conversion luminescence; therefore precursor powders must exhibit high values of up-conversion luminescence efficiency. Single-phase solid solutions based on strontium fluoride doped with ytterbium and erbium were synthesised by co-precipitation from aqueous solutions using sodium fluoride, potassium fluoride and ammonium fluoride as fluorinating agents. The asymmetry of X-ray diffraction maxima indicated the presence of two populations of particles with the same chemical composition. The processes of extended flat particles' growth from smaller particles with a spherical morphology were revealed with transmission electron microscopy and X-ray diffraction. It was shown that when sodium fluoride and potassium fluoride were used they entered the crystal structure in an amount of 3-4 mol% and 1 mol%, respectively. The introduction of sodium and potassium led to an improvement in the sintering ability of particles and a significant increase in the particle size in ceramics by a factor of 5 and 2, respectively, in comparison with the use of ammonium fluoride. The quantum yield values of up-conversion luminescence at the level of tenths of a percent at a low pump power density of 0.1 W cm-2 were very high, which suggests that these synthetic techniques can be considered to be promising for the preparation of precursors of laser ceramics.

Data on physical and electrical properties of (ZrO2)1-x(Sc2O3)x(CeO2)y and (ZrO2)1-x-y-z(Sc2O3)x(CeO2)y(Y2O3)z solid solution crystals.

The data presented in this article are related to the research article entitled "Phase stability and transport characteristics of (ZrO2)1-x(Sc2O3)x(СeO2)y and (ZrO2)1-x-y-z(Sc2O3)x(СeO2)y(Y2O3)z solid solution crystals" https://www.sciencedirect.com/science/article/pii/S2352340917302329 [1]. It contains data on densities and microhardness of the as-grown crystals. The data on the specific conductivity of the as-grown and annealing at 1000 °Ð¡ for 400 h ScCeSZ and ScCeYSZ crystals in the temperature range 623-1173 K is also included in this article. The article describes also the growth of the (ZrO2)1-x(Sc2O3)x(СeO2)y and (ZrO2)1-x-y-z(Sc2O3)x(СeO2)y(Y2O3)z solid solution crystals using directional melt crystallization in a cold crucible.

New functional material: spark plasma sintered Si/SiO2 nanoparticles - fabrication and properties.

A bulk nanostructured material based on oxidized silicon nanopowder was fabricated using a spark plasma sintering technique. Structural investigations revealed that this material has the composition of ∼14 nm core Si granules inside an SiO2 shell. Photoluminescence measurements have shown that the emission spectra lie in the energy range of 0.6-1.1 eV, which is not typical of the emissions of the Si/SiO2 nanostructures reported in numerous papers. This result can be explained by the formation of energy states in the bandgap and the participation of these states in both electronic transport and photoluminescence emission. Annealing of the sample leads to a decrease in defect density, which in turn leads to quenching of the 0.6-1.1 eV photoluminescence. In this case ∼1.13 eV inter-band transitions in the Si core start to play a dominant role in radiative recombination. Thus, the possibility of controlling the photoluminescence emission over a broad wavelength range was demonstrated.