Perovskite materials (ABO3) present considerable technological interest, their properties depend on the A and B elements. A variety of methods have been used for the elaboration of perovskite materials. In the present paper we present the results of the BaHfO3 and BaZrO3 obtained by polyol method. Inorganic salts of barium and hafnium or zirconium were dissolved in di-etilenglicol and the products were heat treated at 700 °C and 900 °C. X-ray diffraction revealed the cubic structure perovskite-type and diffractions corresponding to the secondary phases of BaCO3 and MO2 (M=Hf or Zr). The spectra obtained by FTIR show the presence of BaCO3. At 700 °C, the scanning electronic microscopy observations revealed a very compact morphology conformed by smaller sub-structures in the form of wire with a diameter around to 900 nm. At 900 °C it was observed a remarkable change in the morphology with dispersed materials conformed by small particles. Transmission electronic microscopy showed that the materials annealed at 900 °C are constituted by small crystals with size lower than 15 nm.

Los materiales tipo perovskita (ABO3) presentan considerable interés tecnológico, sus propiedades dependen de los elementos A y B que los sustituyan. Para la elaboración de materiales tipo perovskita se han empleado diversos métodos. En este trabajo se presentan los resultados obtenidos para el BaHfO3 y BaZrO3 utilizando la síntesis poliol. Se usaron sales inorgánicas disueltas en dietilenglicol y los materiales recuperados han sido tratados térmicamente a 700 °C y 900 °C. El análisis por difracción de rayos X reveló la estructura cúbica tipo perovskita y se observaron adicionalmente picos correspondientes a las fases secundarias de BaCO3 y MO2 (M=Hf o Zr) en ambos materiales. Los espectros obtenidos por FTIR pusieron en evidencia la presencia de BaCO3. Las observaciones por microscopía electrónica de barrido revelaron para ambos casos, materiales muy compactos conformados por sub-estructuras más pequeñas en forma de alambre de diámetro aproximado a 900 nm. Para temperaturas de calcinado entre 700ºC y 900ºC se observó un cambio remarcable en la morfología con materiales disgregados conformados por partículas más pequeñas. Los análisis en microscopía electrónica en transmisión revelaron que los materiales tratados a la mayor temperatura están constituidos por pequeños cristales inferiores a 15 nm.

SrHfO3 presents high density, which makes it interesting for host lattice when it is doped with rare earths for luminescent materials. The optical and structural studies of Ce3+-doped strontium hafnate films prepared by the sol-gel process are presented in this work. Crack-free films with waveguiding performances were obtained with heat-treatments between 400°C and 700°C. The total elimination of organic compounds occurs above 800°C as indicated by Fourier transform infrared spectroscopy. The optogeometric properties (refractive index and thickness) are investigated by m-lines spectroscopy. Films structure is analysed using X-ray diffraction and transmission electron microscopy. The films crystallise from amorphous phase to pure SrHfO3 orthorhombic phase at 750°C. The HfO2 monoclinic phase superposes to SrHfO3 orthorhombic phase after heat treatment performed at 1000°C. Finally, the potentiality to prepare Ce3+ activated SrHfO3 sol-gel films with scintillation properties is explored.

A novel approach in utilizing the polyol method was used for the preparation of nanocrystalline and nanostructured undoped and Tb3+-doped Y2O3 materials. By this method, particles in colloidal solution and re-dispersible powders with spherical shape and luminescent properties were formed. The materials were characterised by High Resolution Transmission Electron Microscopy (HRTEM) and Luminescence Spectroscopy (LS). Oxide nanoparticles 5 to 6 nm in size, with homogeneous distribution, good morphology and high crystallinity were obtained, being colloidally stable for weeks. In the case of the re-dispersible powders, nanostructured aggregates 300 to 400 nm in size were observed, containing ultra-small individual nano-oxide bcc crystallites. In addition, the nanocrystalline and nanostructured Tb3+-doped Y2O3 materials showed luminescent properties.