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Low‐temperature phase transformation and phonon confinement in one‐dimensional Ta 2 O 5 nanorods
Author(s) -
Devan Rupesh S.,
Ho WeiDer,
Wu Sheng Yun,
Ma YuanRon
Publication year - 2010
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s002188981000796x
Subject(s) - nanorod , tetragonal crystal system , materials science , orthorhombic crystal system , raman spectroscopy , phonon , phase (matter) , raman scattering , thermochromism , diffraction , condensed matter physics , crystallography , optics , nanotechnology , crystal structure , chemistry , physics , organic chemistry
The thermochromic phase transformations of one‐dimensional Ta 2 O 5 nanorods have been analyzed at elevated temperatures ranging from 80 to 300 K. The nanorods, grown in a large‐area high‐density array, are 14–22 nm wide and approximately 500 nm long. The array contained ∼93.5% of the orthorhombic (β) phase and ∼6.5% of the tetragonal (α) phase. Low‐temperature X‐ray diffraction results showed complex and polymorphic thermochromic phase transformations of the β(001), α(101) and α(103) lattice planes of the nanorods, which incorporate (i) α‐to‐α (α–α), (ii) α–α–β and (iii) α–β phase transitions. In comparison with the Raman scattering of three‐dimensional bulk powder and two‐dimensional thin films of Ta 2 O 5 , there were concurrent Raman blue‐ and redshifts in the one‐dimensional Ta 2 O 5 nanorods, indicating that the molecular vibrations of the nanorods were confined owing to the reduction of size and dimension.