ZTM陶瓷六方钛铁矿结构热稳定性研究

On Improving Significantly the Thermal Stability of Hexagonal Ilmenite Structure of ZnTiO_3

通过 XRD、DTA、光学显微技术 ,系统研究了 (Zn0 .7Mg0 .3 ) Ti O3 (ZTM)陶瓷六方钛铁矿结构的热稳定性和相分解反应 ,应用传统电子陶瓷工艺制备 ZTM陶瓷。实验发现 ,由于 Zn Ti O3 和Mg Ti O3 生成稳定的固溶体 (Zn,Mg) Ti O3 ,六方钛铁矿相在宽广的烧结温度范围内被稳定 ,但烧结温度超过 1 2 5 0℃ ,六方相 (Zn,Mg) Ti O3 将分解为 (Zn,Mg) 2 Ti O4 和 (Zn,Mg) 2 Ti3 O8,这将会引起瓷体的微破裂和致密度的下降。

ZT ceramic ZnTiO 3 becomes unstable when heated above 945℃. We propose using Mg as an additive to stabilize hexagonal ilmenite structure of ZnTiO 3; addition of Mg to ZnTiO 3 produces (Zn,Mg)TiO 3, which we call ZTM ceramic. ZTM ceramic is stable until heated above 1 250℃. We present and discuss the main results of our research in section 2. We found that the pure hexagonal phase of ZTM can be stabilized in a wide sintering temperature range of 900～1 250℃ as shown by our DTA analysis (Fig.1), XRD analysis (Fig.2, Fig.3), and microscopy photographs (Fig.5). In the discussion of Table 1, we explain why ZTM can be stable at a much higher heating temperature. MgTiO 3 has the same ilmenite crystal structure as ZnTiO 3; moreover, the small difference of 0.66 ionic radius of Mg 2+ from 0.74 ionic radius of Zn 2+ allows Mg 2+ to substitute for Zn 2+ easily, so the hexagonal phase is stabilized by the incorporation of MgO into ZnO-TiO 2 system.