Phase formation and electrical characteristic of NASICON ceramics
(State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China)
Abstract: Hot pressed sintering were employed to prepare the sodium super ionic conductor (NASICON: Na3Zr2Si2PO12) ceramics using the powder with the corresponding composition from sol-gel method. The density, phase and microstructure of different samples sintered at different temperatures were analyzed and the dependences of density, phase formation, and the microstructure on the sintering temperature were investigated in detail. The AC electrical conductivity and the buck conductivity of the ceramics sintered at different temperatures were measured and discussed. Results show that the samples contain mainly monoclinic NASICON and no ZrO2 phase was found no matter the sintering temperature is high or not. The sintering temperature mainly dominated the density, the microstructure and the electrical characteristics of the ceramics. The densities of the samples increase obviously as the sintering temperature increases and reach 99.4% when the sintering temperature is 1 150 ℃. With the increase of sintering temperature, both the density and crystal size of the samples increase obviously, resulting in the visible increase of ionic conductivity of the samples as the sintering temperature. When sintering temperature reaches 1 150 ℃, the ionic conductivity of the sample has the highest value of 3.6×10−3 S/cm, which could be attribute to the highest density and least crystal boundary due to largest crystal size of the ceramics.
Key words: NASICON ceramic; hot-press; electrical conductivity; structure; density