Fabrication of Transparent Y_2Hf_2O_7 Ceramic from Combustion Synthesized Powders

Y(NO3)3,HfCl4 and EDTA as raw materials,Y2Hf2O7 nanopowder were successfully prepared by combustion synthesis method.The as-burnt powder were calcined at 1200℃ and then ball-milled for 15h.The powders were formed into green bodies with a size of φ20mm×2.5mm by cold isostatic pressing(CIP,200MPa).Y2Hf2O7 transparent ceramics were obtained by sintering the green bodies at 1850℃ in vacuum for 6h.The resultant ceramics showed a transmittance of 50% in the visible spectral region.The sintering behavior of the prepared Y2Hf2O7 powders was investigated.When the sintering temperature was above 1850℃,sintering temperature had little effect on the transmittance of the ceramic.Meanwhile the grain size became larger with sintering temperature increasing.