doi:10.1016/j.jeurceramsoc.2025.118022engOliete, P.B.Merino, R.I.Peña, J.I.Sanjuán, M.L.Binary and ternary eutectic composites of the CaO – ZrO2 – MgO system for porous ceramic supportsART-2025-146471We recently reported on the use of c-ZrO2-MgO eutectic composites produced by directional solidification as supports for CO2-selective membranes based on molten carbonates. Here, we explore other compositions, particularly within the CaO – ZrO2 – MgO system, with the ultimate goal of improving the membrane permeation by either increasing the support’s ionic conductivity or reducing its tortuosity. The three eutectic-like composites studied display MgO fibres embedded in single-phase or two-phase matrices. The composite with 8.5CaO/48.5ZrO2/43MgO mol% composition consists of MgO fibres in an oxide-ion conducting c-ZrO2 matrix containing both Ca and Mg. A binary CaZrO3 – MgO eutectic-like composite forms at ∼33CaO/35ZrO2/32MgO mol% with MgO fibres in a Ca-poor, Mg-doped CaZrO3 matrix displaying mixed oxide-ion and hole conductivity. For 22CaO/45ZrO2/33MgO mol% composition, a ternary eutectic forms with MgO fibres at the interfaces of CaZrO3 and c-ZrO2 phases. Acid etching tests were conducted to verify the feasibility of fabricating a porous support.2025http://zaguan.unizar.es/record/16503710.1016/j.jeurceramsoc.2025.118022http://zaguan.unizar.es/record/165037oai:zaguan.unizar.es:165037info:eu-repo/grantAgreement/ES/DGA/T02-23Rinfo:eu-repo/grantAgreement/ES/MCINN/FEDER/PID2021-124863OB-I00info:eu-repo/grantAgreement/ES/MICIU/CEX2023-001286-SJournal of the European Ceramic Society 46, 5 (2025), 118022 [12 pp.]by-nc-ndhttps://creativecommons.org/licenses/by-nc-nd/4.0/deed.esinfo:eu-repo/semantics/openAccess