The influence of chemical prehistory on the structure, photoluminescent properties, surface and biological characteristics of Zr$_{0.98}$ Eu$_{0.02}$O$_{1.99}$ nanophosphors

ZrO$_2$ nanoparticles doped with 2 mol.% of EuO$_{1.5}$ were obtained from solutions of inorganic salts, zirconium alkoxide and chelating compounds under hydro and solvothermal conditions. The phase compositions of the synthesized nanophosphors were determined using the methods of X-ray diffraction, photoluminescence and Raman spectroscopy. The changes in a particle size, the value of the specific surface area and its charge depending on the conditions of preparation (the type of solvent, isothermal exposure time) and the precursor nature used in the synthesis were considered. It was found that Zr$_{0.98}$ Eu$_{0.02}$O$_{1.99}$ nanoparticles with a high content of the monoclinic phase, synthesized from zirconium and europium acetylacetonates, have the highest luminescence efficiency. At the same time, the maximum photoluminescence lifetime and the least cytotoxicity were characteristic of crystal phosphors with a more symmetrical crystal lattice of the host matrix, as well as a high surface area/volume ratio.