The Research On Preparation Technology And Sintering Behavior Of Gadolinium Aluminates (GdAlO3)

GdA103with perovskite structure has the thermal conductivity equivalent to yttrium aluminum garnet, and the high thermal shock factor. Its single crystal attracts people’s attention as a new matrix for solid-state lasers and scintillators. As a rare earth aluminates, in addition to the matrix as functional materials, composited with AI2O3can improve high temperature mechanical properties of Al2O3ceramic, but there are few papers reported about its preparation and sintering behaviors. Therefore, the present paper pay the attention to prepare GdAl03powders using sol-gel method and coprecipitation method, studied the sintering behavior of samples. It will provide guidance for the rare earth aluminates to synthesis composite ceramics with alumina.Using the so-gel method, the pure-phase GdAlO3powder was obtained at1000℃with the heat preservation time of2hours, and the average grain size of the powder was about200nm. The sintering experiments foundthat the sintered compacts were not in high densification, the average line expansion coefficients of green compacts and sintered compact were9.67×10-6/℃and1.36×10-5/℃respectively. We adopted Arrhenius formula to calculate the sintering activation energy for GdAlO3, the result were22.4kJ/mol and31.6kJ/mol respectively on the basis of shrinkage and relative density.The pure-phase GdAlO3powder was obtained by coprecipitation method through sintering at1000℃with the preservationtime of2hours, the average grain size of the powder was about100nm, Through the SEM observation, we found that the powers has small size and good dispersion by this prepared method. The sintering experiments indicated that the sintered compact was in high densification, We adopted Arrhenius formula to calculate the sintering activation energy for GdAlO3, the results were37.9kJ/mol and54.7kJ/mol respectively on the basis of shrinkage and relative density.To study the thermal expansion behaviors during the sintering process for a-Al2O3doped with different concentrations of Gd3+, the final shrinkage of the samples increased with the enhancement of Gd3+content, the average particle sizes of the samples reduced, as well as the tempertuare of the samples began to shrink was rising. The results of the thermal expension experiments for samples showed that the average line expansion coefficients and the expansion maximum of the sintered compacts were higher than the green compacts.The novelty of this article is that preparations of GdAlO3. By coprecipitation method, the average grain size of the powder was smaller, and the sintered compact was in high densification. There is no report about the sintering behavior and the thermal expansion behavior, it is important to prepare composite ceramic materials of GdAlO3with alumina.