Phosphors with different morphology, formed under hydrothermal conditions on the basis of ZrO2:Eu$^{3+}$ nanocrystallites

Eu$^{3+}$-doped ZrO$_{2}$ nanostructures in the form of rods, stars, and hollow spheres were prepared by varying hydrothermal conditions. X-ray diffraction, transmission electron microscope, ultraviolet-visible diffuse reflection spectroscopy, low-temperature nitrogen adsorption method, Raman spectroscopy and photoluminescence spectra were used to characterize the polymorph modification, surface and optical properties of the Zr$_{0.98}$Eu$_{0.02}$O$_{2}$ nanophosphors. The Eu$^{3+}$ content in a zirconia monoclinic lattice, remained constant for all types of obtained nanostructures in order to reveal the morphology influence on the efficiency of electronic excitation energy transfer from the host matrix to photoactive centers. The decrease of average size of the coherent scattering regions in the series rods $\to$ stars $\to$ hollow spheres, is associated with increasing the specific surface area values. At that, in the photoluminescence spectrum, the splitting of the sublevels associated with the monoclinic lattice $^{5}$D$_{0}\to{}^{7}$F$_{1}$ disappears.