Preparation of NASIglasses by Sol-Gel Process

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J. Korean Ceram. Soc. > Volume 32(12); 1995 > Article

Journal of the Korean Ceramic Society 1995;32(12): 1357.

솔-젤법에 의한 NASIglass의 제조

김희주, 강은태, 김종옥¹

경상대학교 무기재료공학과
¹배재대학교 무기재료공학과

Preparation of NASIglasses by Sol-Gel Process

ABSTRACT

Nasigels of composition Na0.75Zr2PSi2O12 and Na3Zr2PSi2O12 have been synthesized by the sol-gel technique using metal alkoxide precursors. The monolithic dry gels of Na0.75Zr2PSi2O12 with no crack have been prepared by the control of the shrinkage rte, but gels of Na3Zr2PSi2O12 were impossible to prepare without cracking. The gels treated up to 80$0^{circ}C$ led to the formtion of glass but the glasses were converted to the crystalline phases at above this temperature. Crystaline phases precipitated from the Na0.75Zr2PSi2O12 glass were NASICON-like phase, Na2Si2O5, and free Zirconia. Phase that precipitated from the Na3Zr2PSi2O12 was only rhombohedral NASICON. For Na0.75Zr2PSi2O12 gels, framework of PO4 tetrahedra and SiO4(PO4) tetrahedra formed at low temperature but changed to that of SiO4 and SiO4(PO4) tetrahedras as it were crystallized. In the case of Na3Zr2PSi2O12 gel, framework of isolated PO4 and SiO4 tetrahedras formed at low temperature but changed to SiO4(PO4) tetrahedra framework which usually formed in the NASICON crystal after crystallization at high temperature. The gels treated up to 80$0^{circ}C$ contained the residual water. The ionic conduction was attributed to the motion of proton and Na+ ion at low (up to 150~20$0^{circ}C$) and high temperatures, respectively. As the temperature of heat treatment increased, ionic conductivity gradaully increased with the extent of precipitation of crystalline phase.

Key words: Sol-Gel process, NASIglass, NASICON, Ionic conduction