Oxidation state, local structure distortion, and defect structure analysis of Cu doped α-MnO2 correlated to conductivity and dielectric properties

Erna, Hastuti, Subhan, Achmad, Amonpattaratkit, P., Zainuri, M., Triwikantoro, T. and Suasmoro, S. (2022) Oxidation state, local structure distortion, and defect structure analysis of Cu doped α-MnO2 correlated to conductivity and dielectric properties. Heliyon, 8. pp. 1-13. ISSN 24058440

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Abstract

Cu-doped MnO2 with the composition of Mn1-xCuxO2 (x ¼ 0–0.15) was synthesized and characterized. The synthesis was carried out by hydrothermal method at 140 C for 5 h of reaction dwell time. The characterizations include X-Ray Diffraction (XRD), Microscopy, X-ray Absorption Spectroscopy (XAS), and Impedance complex analysis. It was revealed that all samples have nanorod morphology. Their size increases with the increasing dopant. Additionally, K ions are detected by EDX. All samples pose α-MnO2 type structures performing (2 2) and (1 1) tunnels permitting large ions incorporated and oxygen deficiency. The octahedron was distorted to elongate up to x ¼ 0.10, then compressed for x ¼ 0.15, inducing the Jan Teller effect. Oxidation state analysis revealed that the manganese has Mn3þ and Mn4þ, while the copper is mainly attributed to Cu2þ and Cu3þ respectively. The small ionic size and highly oxidized Cu3þ substitute Mn4þ, while Cu2þ substitutes Mn3þ or simultaneously with the larger Kþ incorporated in the tunnel. Accordingly, the defects to exist in the sample, namely Cu0 Mn, Mn0 Mn, V O , and e 0 . Electrical characterization at room temperature revealed that the conductivity of Cu-doped MnO2 is dominated by electrons influenced by the various oxidation state of the cations in the octa hedron sites, while space charges dominate the dielectric response.

Item Type:	Journal Article
Keywords:	Manganese dioxide; Doping; Oxidation state; Local distortion; Defect structure
Subjects:	02 PHYSICAL SCIENCES > 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics > 020201 Atomic and Molecular Physics
Divisions:	Faculty of Mathematics and Sciences > Department of Physics
Depositing User:	Erna Erna Hastuti
Date Deposited:	17 Apr 2023 12:50

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