Tuning the oxygen vacancy concentration in (GeMnTiSnMo)O2 high-entropy oxides for high dielectric through In2O3 doping

TiO 2 -based materials are widely used in high-temperature capacitors and aerospace electronics but face challenges such as high dielectric loss and limited thermal stability in conventional single-component systems. To address these issues, we propose a novel strategy integrating high-entropy doping design and oxygen vacancy engineering. In 2 O 3 -doped (GeMnTiSnMo)O 2 high-entropy ceramics (GMTSMO- x In, x  = 0.1–1) were synthesized via solid-state reaction. Experimental results reveal that In 3+ doping generates high-density oxygen vacancies (V o ·· ) through charge compensation, forming [Ti 3+ - V o ·· -Ti 3+ ] and [Mn 3+ - V o ·· -Mn 3+ ] defect-dipole clusters. These clusters enhance electron localization and suppress carrier migration, reducing dielectric loss by threefold. Simultaneously, oxygen vacancy enrichment strengthens interfacial polarization, increasing the dielectric constant by fourfold. The optimal GMTSMO-0.5In exhibits a relative permittivity ( ε r ) of 4.0 × 10 6 and a low loss tangent of 15 at 650 ℃/100 Hz, outperforming traditional TiO 2 -based materials and existing high-entropy oxides. All compositions demonstrate excellent temperature stability (25–400 ℃) and frequency-independent behavior above 10 4  Hz. This work provides a high-entropy-driven approach for dynamic defect engineering, paving the way for advanced dielectric materials in extreme-condition energy storage systems.