Structural and morphological evolution of beta-MnO2 nanorods during hydrothermal synthesis.
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.
Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Oslo, Norway. tao.gao@kjemi.uio.no
Tao
T
Gao
Helmer
H
Fjellvåg
Poul
P
Norby
D003460:Crystallization / Q000379:methods*; D006358:Hot Temperature; D046911:Macromolecular Substances / Q000737:chemistry; D017895:Manganese Compounds / Q000737:chemistry*; D008422:Materials Testing; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure*; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D014867:Water / Q000737:chemistry
D046911:Macromolecular Substances; D017895:Manganese Compounds; D010087:Oxides; D014867:Water; C027424:manganese oxide