Interfacial phase evolution and local structural symmetry in multiphase BaTiO3-Co0.5Mn0.5Fe1.98Nb0.02O4 ceramics: Unraveling in-situ barium hexaferrite formation, transport, and magnetic properties
Ceramics International, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.ceramint.2026.08.397
- Dergi Adı: Ceramics International
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Anahtar Kelimeler: Electrical resistivity, Ferroelectric properties, Magnetic properties, Magneto-dielectric composites, Microstructure
- Çukurova Üniversitesi Adresli: Evet
Özet
Multiferroic composites offer a promising framework for room-temperature multifunctional materials by combining distinct ferroic orders across phase boundaries. In this study, BaTiO3/Co0.5Mn0.5Fe1.98Nb0.02O4 (BTO-CMFNO) composite ceramics were prepared by high-temperature solid-state consolidation. Multiphase XRD Rietveld refinements, complemented by SEM/EDX and HR-TEM analyses, confirmed a tri-phase architecture comprising BaTiO3, spinel ferrite, and the in-situ growth of an M-type barium hexaferrite (BaFe12O19) interphase. Notably, while bulk XRD showed a pseudo-cubic profile broadening, local HR-TEM and SAED spot arrays provided qualitative evidence of nanoscale rectangular symmetry consistent with tetragonal distortions in the BaTiO3 matrix. Evaluating the optical diffuse reflectance via Tauc plots yielded effective bulk optical absorption edges (Eg) decreasing from 1.44 eV (BTO-CMFNO25) to 1.35 eV (BTO-CMFNO75) for direct transitions, driven by lower-energy Fe3+ electronic transitions. Temperature-dependent electrical transport measurements demonstrated that BTO-CMFNO25 limits conductive leakage pathways, maintaining a high room-temperature electrical resistivity of ∼1.0 × 108 Ω cm. Polarization P(E) hysteresis loops showed that while BTO and BTO-CMFNO25 display characteristic ferroelectric-like response, higher ferrite loadings (BTO-CMFNO50 and BTO-CMFNO75) transition into lossy, elliptical P(E) loops due to ohmic leakage through the percolating ferrite network. Conversely, room-temperature magnetic measurements revealed smooth, kink-free M(H) loops and unimodal dM/dH switching field distributions consistent with cooperative magnetization reversal between the soft spinel and in-situ hard BaFe12O19 phases, reaching a maximum saturation magnetization (Ms) of 25.8 emu/g. These findings establish key processing-microstructure-property relationships in in-situ tri-phase ceramics, identifying BTO-CMFNO25 as a primary baseline structure for future magnetoelectric coupling studies, while establishing prospective transport and magnetic guidelines for high-frequency and sensing hypotheses.