Solid State reactions and doping of oxides induced by ball milling

CECILIA Y. CHAIN; RUBÉN A. QUILLE; ALBERTO F. PASQUEVICH

Buenos Aires

Simposio; 15th International Symposium on Metastable, Amorphous and Nanostructured Materials; 2008

Ball milling can be used to induce solid state reactions  in oxides. Also the technique can be used for doping oxides of technological interest. We applied this method for doping oxides with radioactive 181Hf. These  isotopes decay to 181Ta which are adequate probes for Perturbed Angular Correlations (PAC) studies.  Through the measurements of the hyperfine interactions of Ta  nuclei it is possible to determine the atomic  distribution around the probes. We have studied the solid state reactions and the alloying at atomic scale in the binary HfO2 – M2O3 ceramic systems (M= In, La).   The radioactive isotope was introduced in the samples  using HfO2, where the 180Hf was activated by thermal neutron capture at the CNEA reactor.   Blends of the  oxides, using few atomic percent of hafnium oxide, were milled during several hours.  PAC measurements of the samples at room temperature were carried out  after  milling treatments  and after thermal annealing at high temperature.  In the case of blends with indium oxide the results are compared with those obtained after doping with Hafnium by sol - gel method. The formation of a Hf defective oxide phase was detected. The hyperfine parameters corresponding to this phase are compared with those observed in PAC experiments using milling and ZrO2 based blends. In the  case of blends with La2O3 the formation of Hf2La2O7 pyrochlore  has been observed