LAUSR

Abstract The present work describes the sintering and ionic conductivity of rare-earth-based fluorobritholite (Sr8La2-xNdx(PO4)4(SiO4)2F2 with 0 ≤ x ≤ 2). The materials were prepared via conventional solid state reactions. The analysis and characterization of the synthesized powders were carried out using several techniques. The samples’ ionic conductivity σ was measured via a complex impedance spectroscopy. The results showed that the substitution of lanthanum and/or neodymium by strontium and silicates by phosphorus in fluorapatite has been established and well-crystallized single-phase apatites were consequently obtained as a result. The neodymium-lanthanum substitution was total according to the small dimensional differences between the two cations. Next, the powders were after that compacted into pellets and then pressurelessly sintered at a 1250–1450 °C temperature range. The relative densities of the sintered bodies were found to depend on sintering temperature as well as on Nd content. The 90% relative density was obtained with x = 2 sample sintered at 1250 °C. The microstructures of the densest bodies were characterized by a closed porosity. The measured ionic conductivity σ of the samples was found to depend simultaneously on both the Nd content and the heating temperatures, while the maximum value of 2.73 10−6 S cm−1 was obtained at 780 °C for x = 2. A correlation between material structures and densification ratios with the ionic conductivity σ was detailed.