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<p>In this work, the low cost and eco-friendly CaMnO<sub>3-δ</sub> perovskite has been prepared by sol-gel method. Rietveld refinement of XRD data indicated that CaMnO<sub>3-δ</sub> sample crystallized in orthorhombic structure with space group Pnma. Further characterizations of this sample were performed employing TEM, SAED pattern, HR-TEM, and EDS elemental mapping. These measurements show that the CaMnO<sub>3-δ</sub> sample has polycrystalline nature with high degree of crystallinity and all elements are homogeneously distributed. The oxidation states of Mn ions and the presence of oxygen vacancies in this sample were confirmed by XPS analysis. Optical studies revealed that CaMnO<sub>3-δ</sub> sample has direct band gap energy (E<sub>g</sub>) of 3.63 eV using UV–vis spectroscopy. Asymmetric magnetic hysteresis (M − H) loop in CaMnO<sub>3-δ</sub> nanoparticles reveals that the presence of exchange bias phenomenon at room temperature. The present work provides the observation of pseudocapacitive behavior in CaMnO<sub>3-δ</sub> nanoparticles. Furthermore, the presence of oxygen vacancies and Mn oxidation states in CaMnO<sub>3-δ</sub> sample enhanced the charge storage capability by oxygen intercalation. These results prove that CaMnO<sub>3-δ</sub> perovskite is a promising material for magnetic and energy-storage applications.</p> Graphical Abstract <p></p>

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Study the role of oxygen vacancies and Mn oxidation states in nonstoichiometric CaMnO3-δ perovskite nanoparticles

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年1月4日

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  • E. K. Abdel-Khalek,
  • E. A. Mohamed,
  • Yasser A. M. Ismail

摘要

In this work, the low cost and eco-friendly CaMnO3-δ perovskite has been prepared by sol-gel method. Rietveld refinement of XRD data indicated that CaMnO3-δ sample crystallized in orthorhombic structure with space group Pnma. Further characterizations of this sample were performed employing TEM, SAED pattern, HR-TEM, and EDS elemental mapping. These measurements show that the CaMnO3-δ sample has polycrystalline nature with high degree of crystallinity and all elements are homogeneously distributed. The oxidation states of Mn ions and the presence of oxygen vacancies in this sample were confirmed by XPS analysis. Optical studies revealed that CaMnO3-δ sample has direct band gap energy (Eg) of 3.63 eV using UV–vis spectroscopy. Asymmetric magnetic hysteresis (M − H) loop in CaMnO3-δ nanoparticles reveals that the presence of exchange bias phenomenon at room temperature. The present work provides the observation of pseudocapacitive behavior in CaMnO3-δ nanoparticles. Furthermore, the presence of oxygen vacancies and Mn oxidation states in CaMnO3-δ sample enhanced the charge storage capability by oxygen intercalation. These results prove that CaMnO3-δ perovskite is a promising material for magnetic and energy-storage applications.

Graphical Abstract