Effect of Microwave and Conventional Processing on the Sintering of Aluminium-Doped Lanthanum Germanium-Based Electrolyte Material (La 9.5 Ge 5.5 Al 0.5 O 26 ) Calcined by Microwave and Electric Heating

The current study reports the sintering of an aluminium-doped lanthanum germanium-based electrolyte material with the composition La9.5Ge5.5Al0.5O26, performed under both microwave energy and conventional heating. The precursor of the composition La9.5Ge5.5Al0.5O26 was prepared using the mixed oxide method, and the precursor was calcined at 900°, 1000° and 1100°C for 1 h to optimize the minimum calcination temperature for achieving a single phase of La9.5Ge5.5Al0.5O26. The precursor was calcined at 1100°C for 1 h by conventional heating. The calcined powder obtained by microwave and electric heating was sintered at 1350°C for 30 min duration by microwave heating and for 4 h duration at the same temperature by conventional heating. X-ray diffraction (XRD) revealed that the conventionally sintered sample was of a single phase. But when it was further investigated by microwave Raman spectroscopy, it showed the presence of a monoclinic phase (La2GeO5) along with a hexagonal phase. But samples sintered by microwave energy had resulted in the formation of a single hexagonal phase, which was revealed by both XRD and micro Raman spectroscopy. Microwave sintered AlMCMS and AlCCMS samples showed higher conductivity values of 2.21×10–3 and 1.59×10–3 S.cm–1 at 650°C, respectively, whereas conventionally sintered AlMCCS and AlCCCS samples exhibited lower conductivity values of 4.18×10–4 and 5.62×10–4 S.cm–1, respectively, at 650°C.