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<p>Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-based oxide ion conductors exhibit significant potential for applications in intermediate-temperature solid oxide fuel cells. The electrical performance of the material was enhanced by doping with Cu<sup>2+</sup> ions. Na<sub>0.51</sub>Bi<sub>0.49</sub>Ti<sub>1-x</sub>Cu<sub>x</sub>O<sub>3-δ</sub> (<i>x</i> = 0, 0.005, 0.01, 0.02) samples were synthesized via the conventional solid-state reaction method to investigate their electrical properties and oxygen relaxation behavior. With increasing Cu<sup>2+</sup> ion doping content, the bulk conductivity of Na<sub>0.51</sub>Bi<sub>0.49</sub>Ti<sub>1-x</sub>Cu<sub>x</sub>O<sub>3-δ</sub> samples initially rises, reaching a peak at 1&#xa0;mol% doping level, before gradually declining. At 753&#xa0;K, the bulk conductivity of the Na<sub>0.51</sub>Bi<sub>0.49</sub>Ti<sub>0.99</sub>Cu<sub>0.01</sub>O<sub>3-δ</sub> (<i>x</i> = 0.01) sample can achieve at 4.87 × 10<sup>–5</sup> S/cm, around 11.6 times higher than that of the undoped Na<sub>0.51</sub>Bi<sub>0.49</sub>TiO<sub>3-δ</sub> (<i>x</i> = 0) sample. By the analysis of the dielectric relaxation spectroscopy, the enhanced oxide ion conductivity in the Na<sub>0.51</sub>Bi<sub>0.49</sub>Ti<sub>0.99</sub>Cu<sub>0.01</sub>O<sub>3-δ</sub> (x = 0.01) sample can be attributed to a higher concentration of mobile oxygen vacancies and enhanced oxygen vacancy mobility, as evidenced by the reduced relaxation activation energy. By the equimolar Mg<sup>2+</sup> and Cu<sup>2+</sup> doping in the B-site, the bulk conductivity of Na<sub>0.51</sub>Bi<sub>0.49</sub>Ti<sub>0.99</sub>Mg<sub>0.01</sub>O<sub>3-δ</sub> sample reaches 1.09 × 10<sup>–4</sup> S/cm at 583&#xa0;K, 3.9 times higher than that of the Na<sub>0.51</sub>Bi<sub>0.49</sub>Ti<sub>0.99</sub>Cu<sub>0.01</sub>O<sub>3-δ</sub> sample. By the calculations using the CI-NEB method, the oxygen migration barrier of the Bi-Bi-Mg migration gate in the Na<sub>0.51</sub>Bi<sub>0.49</sub>Ti<sub>0.99</sub>Mg<sub>0.01</sub>O<sub>3-δ</sub> sample is lower than that of the Bi-Bi-Cu migration gate in the Na<sub>0.51</sub>Bi<sub>0.49</sub>Ti<sub>0.99</sub>Cu<sub>0.01</sub>O<sub>3-δ</sub> sample, indicating that there is a higher mobility of the oxygen vacancies in the Na<sub>0.51</sub>Bi<sub>0.49</sub>Ti<sub>0.99</sub>Mg<sub>0.01</sub>O<sub>3-δ</sub> sample. These results hold substantial importance for enhancing the electrical performance of Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-based oxygen ion conductors, offering valuable insights for future improvements in material design and application.</p>

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Oxygen relaxation behavior and conductivity correlation in Na0.51Bi0.49Ti1-xCuxO3-δ ceramics

  • 期刊论文

  • 发表日期：

    2026年1月6日

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  • Xinyu Hu,
  • Qinfu Zhao,
  • Han Wang,
  • Jiamiao Tuo,
  • Weiguo Wang,
  • Shuyao Cao,
  • Lei Chen,
  • Qiang Liu,
  • Fang Kang,
  • Ping Zhang,
  • Xianyu Li,
  • Gangling Hao

摘要

Na0.5Bi0.5TiO3-based oxide ion conductors exhibit significant potential for applications in intermediate-temperature solid oxide fuel cells. The electrical performance of the material was enhanced by doping with Cu2+ ions. Na0.51Bi0.49Ti1-xCuxO3-δ (x = 0, 0.005, 0.01, 0.02) samples were synthesized via the conventional solid-state reaction method to investigate their electrical properties and oxygen relaxation behavior. With increasing Cu2+ ion doping content, the bulk conductivity of Na0.51Bi0.49Ti1-xCuxO3-δ samples initially rises, reaching a peak at 1 mol% doping level, before gradually declining. At 753 K, the bulk conductivity of the Na0.51Bi0.49Ti0.99Cu0.01O3-δ (x = 0.01) sample can achieve at 4.87 × 10–5 S/cm, around 11.6 times higher than that of the undoped Na0.51Bi0.49TiO3-δ (x = 0) sample. By the analysis of the dielectric relaxation spectroscopy, the enhanced oxide ion conductivity in the Na0.51Bi0.49Ti0.99Cu0.01O3-δ (x = 0.01) sample can be attributed to a higher concentration of mobile oxygen vacancies and enhanced oxygen vacancy mobility, as evidenced by the reduced relaxation activation energy. By the equimolar Mg2+ and Cu2+ doping in the B-site, the bulk conductivity of Na0.51Bi0.49Ti0.99Mg0.01O3-δ sample reaches 1.09 × 10–4 S/cm at 583 K, 3.9 times higher than that of the Na0.51Bi0.49Ti0.99Cu0.01O3-δ sample. By the calculations using the CI-NEB method, the oxygen migration barrier of the Bi-Bi-Mg migration gate in the Na0.51Bi0.49Ti0.99Mg0.01O3-δ sample is lower than that of the Bi-Bi-Cu migration gate in the Na0.51Bi0.49Ti0.99Cu0.01O3-δ sample, indicating that there is a higher mobility of the oxygen vacancies in the Na0.51Bi0.49Ti0.99Mg0.01O3-δ sample. These results hold substantial importance for enhancing the electrical performance of Na0.5Bi0.5TiO3-based oxygen ion conductors, offering valuable insights for future improvements in material design and application.