Synthesis of nano-crystalline apatite type electrolyte powders for solid oxide fuel cells

Rare earth silicates with apatite structure are being actively studied as an alternative electrolyte material for solid oxide fuel cells (SOFC) operating in the intermediate temperature range. In this paper we report on the synthesis of La9.33+x/3AlxSi6−xO26+δ (with x = 0–1.5) and La9.83Fe1.5Si4.5O26 powders using a modified sol–gel process. The parameters involved in the process have been optimized for preparing phase pure, homogeneous and nanometer sized powders. The obtained powders were characterized using scanning electron microscopy, X-ray diffraction and thermal analysis. Pressureless sintering experiments were performed and pellets having relative densities greater than 96% could be obtained after 5 h dwelling in the temperature range between 1500 and 1550 °C.