Influence of ferric oxide on the crystallization of Li-Zn ferrite anorthite and hematite phases at low temperature ceramic glaze

Abstract

© 2015 Elsevier Ltd. The crystallization mechanism and properties of lithium zinc ferrite (LiZnFe<inf>2</inf>O<inf>4</inf>) anorthite (CaAl<inf>2</inf>Si<inf>2</inf>O<inf>8</inf>) and hematite (α-Fe<inf>2</inf>O<inf>3</inf>) of ceramic glaze containing Li<inf>2</inf>O and ZnO system were studied as a function of Fe<inf>2</inf>O<inf>3</inf> contents. The glaze was fired at 1100°C and the addition of 5-25wt.% Fe<inf>2</inf>O<inf>3</inf> contents developed brown color crystals. A non-isothermal analysis was performed to study the crystallization behavior of LiZnFe<inf>2</inf>O<inf>4</inf> anorthite and hematite using DTA with various heating rates for calculating activation energy and Avrami constant from Kissinger and Augis-Bennett equation. XRD, SEM/EDS and Raman spectroscopy were used to determine the crystalline phases. The occurrence of LiZnFe<inf>2</inf>O<inf>4</inf> anorthite and hematite depended on the Fe<inf>2</inf>O<inf>3</inf> content in the glaze. In the case of 15wt.% Fe<inf>2</inf>O<inf>3</inf> demonstrated the main crystalline phase of LiZnFe<inf>2</inf>O<inf>4</inf>. Furthermore, anorthite and hematite were also found in 25wt.% Fe<inf>2</inf>O<inf>3</inf> content. The values of Avrami constant were 0.9 and 0.5, and the surface crystallization tendency is dominant for these crystalline phases.