Open AccessAtomic-level imaging of Mo-V-O complex oxide phase intergrowth, grain boundaries, and defects using HAADF-STEM
Author(s) -
William D. Pyrz,
Douglas A. Blom,
Masahiro Sadakane,
Katsunori Kodato,
Wataru Ueda,
Thomas Vogt,
Douglas J. Buttrey
Publication year - 2010
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.1001239107
Subject(s) - scanning transmission electron microscopy , crystallography , orthorhombic crystal system , phase (matter) , atomic units , materials science , grain boundary , complex oxide , domain (mathematical analysis) , trigonal crystal system , transmission electron microscopy , dark field microscopy , microscopy , crystal structure , oxide , chemistry , optics , nanotechnology , physics , microstructure , mathematical analysis , quantum mechanics , metallurgy , mathematics , organic chemistry
In this work, we structurally characterize defects, grain boundaries, and intergrowth phases observed in various Mo-V-O materials using aberration-corrected high-angle annular dark-field (HAADF) imaging within a scanning transmission electron microscope (STEM). Atomic-level imaging of these preparations clearly shows domains of the orthorhombic M1-type phase intergrown with the trigonal phase. Idealized models based on HAADF imaging indicate that atomic-scale registry at the domain boundaries can be seamless with several possible trigonal and M1-type unit cell orientation relationships. The alignment of two trigonal domains separated by an M1-type domain or vice versa can be predicted by identifying the number of rows/columns of parallel symmetry operators. Intergrowths of the M1 catalyst with the M2 phase or with the Mo5 O14 -type phase have not been observed. The resolution enhancements provided by aberration-correction have provided new insights to the understanding of phase equilibria of complex Mo-V-O materials. This study exemplifies the utility of STEM for the characterization of local structure at crystalline phase boundaries.