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<p>Oxide nanomaterials possessing fluorite-type crystal structures, such as ceria (cerium oxide) and zirconia (zirconium oxide) are well known for their multifunctional properties, including optical, magnetic, catalytic, electrical and electrochemical characteristics, enabling a wide range of applications. In recent years, a new concept of high entropy oxides composed of multiple metal cations has been emerged, wherein configurational entropy plays a crucial role in stabilizing a single-phase solid solution. In the present study, ceria-based fluorite structured high entropy oxides (FS-HEOs) namely Ce<sub>0.2</sub>Zr<sub>0.2</sub>Sm<sub>0.2</sub>Gd<sub>0.2</sub>(La/Y)<sub>0.2</sub>O<sub>2–δ</sub> (CZSGL and CZSGY) were successfully synthesized via a sol-gel method. The structural, morphological, electrical, dielectric, and electrochemical (CV and GCD) properties were systematically investigated. The prepared ceria-based FS-HEOs were confirmed with a single phase pure fluorite structure after calcination at 800°C and sintering at 1100°C. The crystal structure, surface morphology, elemental composition, chemical states, and structural features of the compositions were thoroughly examined. Impedance spectroscopy revealed total electrical conductivities of 1.4 × 10<sup>–4</sup> S/cm at 500°C and 3.57 × 10<sup>–4</sup> S/cm at 600°C for CZSGL (with activation energy of 0.80&#xa0;eV) and 2.0 × 10<sup>–4</sup> S/cm at 500°C and 1.1 × 10<sup>–3</sup> S/cm at 600°C for CZSGY (with activation energy of 0.75&#xa0;eV), demonstrating its potential as a solid electrolyte for intermediate-temperature energy conversion devices. Dielectric studies demonstrated high dielectric constant (ε’ ~1000) with low tan δ &lt; 0.04 at 1&#xa0;MHz, indicating suitability for high-frequency capacitors and microelectronic applications. Electrochemical measurements (CV and GCD) revealed maximum specific capacitance 59&#xa0;F g⁻¹ (CZSGY), highlighting the potential use of CZSGY as an electrode material for energy storage devices. Overall, the present work demonstrates that entropy-engineered fluorite oxides can simultaneously deliver ionic transport, dielectric functionality, and electrochemical activity, underscoring their multifunctional applicability in next-generation energy conversion and storage technologies.</p>

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Multifunctional property evaluation of fluorite-structured high-entropy oxides Ce0.2Zr0.2Sm0.2Gd0.2(La/Y) 0.2O2–δ

  • 期刊论文

  • 发表日期：

    2026年5月15日

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  • Kasarapu Venkataramana,
  • Y. Ranjith Kumar,
  • M. Vasundhara

摘要

Oxide nanomaterials possessing fluorite-type crystal structures, such as ceria (cerium oxide) and zirconia (zirconium oxide) are well known for their multifunctional properties, including optical, magnetic, catalytic, electrical and electrochemical characteristics, enabling a wide range of applications. In recent years, a new concept of high entropy oxides composed of multiple metal cations has been emerged, wherein configurational entropy plays a crucial role in stabilizing a single-phase solid solution. In the present study, ceria-based fluorite structured high entropy oxides (FS-HEOs) namely Ce0.2Zr0.2Sm0.2Gd0.2(La/Y)0.2O2–δ (CZSGL and CZSGY) were successfully synthesized via a sol-gel method. The structural, morphological, electrical, dielectric, and electrochemical (CV and GCD) properties were systematically investigated. The prepared ceria-based FS-HEOs were confirmed with a single phase pure fluorite structure after calcination at 800°C and sintering at 1100°C. The crystal structure, surface morphology, elemental composition, chemical states, and structural features of the compositions were thoroughly examined. Impedance spectroscopy revealed total electrical conductivities of 1.4 × 10–4 S/cm at 500°C and 3.57 × 10–4 S/cm at 600°C for CZSGL (with activation energy of 0.80 eV) and 2.0 × 10–4 S/cm at 500°C and 1.1 × 10–3 S/cm at 600°C for CZSGY (with activation energy of 0.75 eV), demonstrating its potential as a solid electrolyte for intermediate-temperature energy conversion devices. Dielectric studies demonstrated high dielectric constant (ε’ ~1000) with low tan δ < 0.04 at 1 MHz, indicating suitability for high-frequency capacitors and microelectronic applications. Electrochemical measurements (CV and GCD) revealed maximum specific capacitance 59 F g⁻¹ (CZSGY), highlighting the potential use of CZSGY as an electrode material for energy storage devices. Overall, the present work demonstrates that entropy-engineered fluorite oxides can simultaneously deliver ionic transport, dielectric functionality, and electrochemical activity, underscoring their multifunctional applicability in next-generation energy conversion and storage technologies.