High entropy engineering ceramics: a critical review of mechanical, structural, thermal and electrical properties

High entropy oxides (HEOs) have emerged as a transformative class of materials, stabilized by configurational entropy and lattice distortion, offering multifunctional properties across mechanical, structural, thermal, electrical, and catalytic domains. This review provides a comprehensive synthesis of current knowledge, critically evaluating processing pathways, property correlations, and application areas ranging from energy storage and catalysis to thermoelectrics and environmental technologies. The novelty of this review lies in its integrative framework: mapping research gaps across temporal, methodological, application, materials, and conceptual dimensions; introducing comparative tables and schematic visualizations that unify diverse findings into defense ready, presentation friendly formats; highlighting entropy driven multifunctionality as the central paradigm linking synthesis, properties, and applications into a coherent roadmap; and proposing future directions that combine computational design, scalable green synthesis, defect engineering, and sustainability to accelerate translation into real world devices. By bridging fundamental insights with practical applications and embedding novelty through structured gap analysis, visual synthesis, and entropy centered roadmaps, this review positions HEOs as cornerstone materials in the pursuit of resilient energy, electronic, and environmental systems.