Structural and morphological evolution of beta-MnO2 nanorods during hydrothermal synthesis
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Updated: Jun 23, 2026
Manganese Oxide Nanoparticle Synthesis by Thermal Decomposition of Manganese(II) Acetylacetonate
Published on: June 18, 2020
Tao Gao1, Helmer Fjellvåg, Poul Norby
1Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Oslo, Norway. tao.gao@kjemi.uio.no
Abstract:
Beta-MnO(2) nanorods were synthesized via a redox reaction of (NH(4))(2)S(2)O(8) and MnSO(4) under hydrothermal conditions. In situ and ex situ x-ray diffraction and scanning electron microscopy were employed to follow the structural and morphological evolution during growth. It was found that the crystallization of beta-MnO(2) nanorods proceeds through two steps: gamma-MnO(2) nanorods form first via a dissolution-recrystallization process and then transform topologically into beta-MnO(2) with increasing temperature. The phase transformation was associated with a short-range rearrangement of MnO(6) octahedra. Vibrational spectroscopic studies showed that the beta-MnO(2) nanorods had four infrared absorptions at 726, 552, 462 and 418 cm(-1) and four Raman scattering bands at 759 (B(2g)), 662 (A(1g)), 576 (Ramsdellite impurity) and 537 (E(g)) cm(-1), which are in agreement with Mn-O lattice vibrations within a rutile-type MnO(6) octahedral matrix.
