Journal of Materials Science and Engineering A 2 (7) (2012) 550-559 Sintering Study of Ceramic Material Based on Magnesium Titanate in Presence of Lithium Fluoride Additives Ahmad Kassas 1 , Jérôme Bernard 2 , Céline Lelievre 2 , David Houivet 2 and Tayssir Hamieh 1 1. Laboratory of Materials, Catalysis, Environment and Analytical Methods (MCEMA‐CHAMSI), Faculty of Agricultural Engineering and Veterinary Medicine and Faculty of Sciences, Lebanese University, Beirut, Lebanon 2. LUSAC (EA4253), Site Universitaire, B.P. 78, 50130 CHERBOURG-OCTEVILLE, France Received: April 21, 2011 / Accepted: May 12, 2011 / Published: July 10, 2012. Abstract: Ceramic porous MgTiO 3 materials have been prepared by classical solid-state route. The sintering of ceramic samples with different LiF contents was studied using dilatometric, thermogravimetric, X-ray diffraction and microstructural analysis. The investigations results showed that the microstructure and porosity of samples were sensitive to LiF percents which generated a liquid phase eutectic (LiF-MgF 2 ), during the heating. Also, the Mg/Ti ratio took part in the structure formation of the ceramic. High grains size layers with cubic orientation were detected at the surface of pellets sintered in air, at 900-1,000 °C, identified as Li 2 MgTiO 4 phase, regardless of LiF amount. At 1,100 °C, the Mg 2 TiO 4 compound, rich in Li, was found on the surface. The pores distribution in studied ceramics; depending on sintering temperature and LiF contents, has been obtained by Mercury porosimetry measurements. In these experimental conditions, dense ceramics could not be obtained, independently of the LiF amount. Key words: Porous ceramic, magnesium titanate, sintering, surface structure. 1. Introduction Because of their good dielectrics properties, dielectrics materials based on magnesium titanate MgTiO 3 (ilmenite structure) are currently used for the fabrication of type I ceramic capacitors [1], and in the microwave communication systems [2]. Many researchers made efforts to decrease the sintering temperature, study the microstructures and the microwave dielectric properties of MgTiO 3 ceramics by adding various additives or varying the processing [3]. The liquid phase sintering by adding glass or low melting point materials was found to effectively lower the firing temperature. Huang et al. reported that 0.95 MgTiO 3 -0.05 CaTiO 3 ceramics doping with 2 wt.% B 2 O 3 addition can be sintered at 1,200 °C [4]. They are also investigated the decomposition reactions of MgTiO 3 in presence of Corresponding author: Ahmad Kassas, Ph.D., research fields: inorganic materials, ceramic materials. E-mail: a.kassas.mcema@ul.edu.lb. Lithium borosilicate “LBS” glass [5]. Whatever, the sintering temperature of MgTiO 3 ceramics is close to 1,350 °C, but it can be lowered when a lithium salt is added [1]. As mentioned in previous studies the densification of MgTiO 3 ceramics with Li compounds addition can lead to the formation of rock-salt type phase: Li 2 MgTiO 4 [6]. This phase seems to modify strongly the microstructure and properties of the magnesium titanate. More precisely, the surface of MgTiO 3 ceramics sintered in presence of LiF is particularly affected [6]. Thus, it is prerequisite to understand the material reactions during the sintering process under the presence of LiF, because these reactions influence the densification process as well as the resultant electric and dielectric properties. 2. Experiments The magnesium titanate powder (MgTiO 3 ), with a stoechiometric ratio Mg/Ti = 1.025 was synthesized by DAVID PUBLISHING D