Etudiant : BOURKIRA MOHAMMED

Filière : Master Matériaux Avancés et Applications (M2A)

Encadrant : Pr. AHFIR RACHID

Annèe : 2026

Résumé : This work investigates two perovskite oxide systems through synthesis, structural characterization, and property analysis. In the first part, rare-earth-doped lanthanum manganite (LaMnO₃) was synthesized by the solid-state method and sintered at 1200°C and 1300°C. X-ray diffraction and FTIR confirmed phase purity in all samples, while SEM revealed a transition from rounded grains in the pure sample to faceted grains in the doped samples, with grain size generally decreasing upon doping, most markedly for the Tb-doped sample. Dielectric measurements showed a normal response for the pure sample sintered at 1200°C, a Drude-type behavior at 1300°C attributed to larger grain size, and a normal decreasing response for the doped samples linked to increased grain boundary density. In the second part, LaNiO₃ was synthesized via conventional sol-gel and Pechini sol-gel routes. The conventional method failed to yield a pure phase, whereas the Pechini method, optimized at pH = 7.5, an EG:CA ratio of 2:1, and a calcination temperature of 800°C, produced a single phase with improved crystallite growth. These results show that the structural, microstructural, and dielectric properties of perovskite oxides are governed by the synthesis route and processing conditions, and they open the way to future optimization for applications such as solid oxide fuel cell cathodes or catalytic materials.