TITLE:
Synthesis, Structural Characterization, and Thermal Insulation Properties of SrLaM0.5Al0.5O4 (M = Mn, Fe, Co) Ruddlesden-Popper Oxides
AUTHORS:
Alexa D. Azure, Md. Sofiul Alom, Helena Mack, Ram Krishna Hona
KEYWORDS:
Ruddlesden-Popper Oxide, Thermal Conductivity, Thermal Insulation, Solid-State Synthesis, Phonon Scattering, XRD, SEM
JOURNAL NAME:
Journal of Materials Science and Chemical Engineering,
Vol.14 No.7,
July
9,
2026
ABSTRACT: Ruddlesden-Popper (RP) oxide phases with the general formula An+1BnO3n+1 have attracted significant interest as thermally insulating ceramics owing to their intrinsic layered crystal architecture, which promotes strong phonon scattering. In the present work, three novel n = 1 Ruddlesden-Popper oxides, SrLaMn0.5Al0.5O4, SrLaFe0.5Al0.5O4, and SrLaCo0.5Al0.5O4, were successfully synthesized by a conventional solid-state reaction route. Phase purity and crystal structure were confirmed by X-ray diffraction (XRD) analysis, which revealed a tetragonal K2NiF4-type structure (space group I4/mmm) consistent with previously reported RP phases. Surface morphology and grain characteristics were examined by scanning electron microscopy (SEM). Thermal conductivity measurements demonstrate that all three compositions exhibit notably low thermal conductivity, with SrLaMn0.5Al0.5O4 achieving the lowest value of 0.204 W/mK, followed by SrLaCo0.5Al0.5O4 (0.326 W/mK) and SrLaFe0.5Al0.5O4 (0.496 W/mK). The superior thermal insulation performance of the Mn-containing compound is attributed to enhanced mass-contrast disorder at the B-site arising from the larger atomic-mass difference between Mn and Al, together with stronger phonon-phonon Umklapp scattering and increased grain-boundary density observed in SEM. These results establish SrLaMn0.5Al0.5O4 as a promising low-thermal-conductivity oxide ceramic, with potential relevance to thermal barrier coating and high-temperature insulation applications.