Dynamic visualization of the phase transformation path in LiFePO4 during delithiation

Transmission electron microscopy (TEM) and nanoindentation, both with in situ heating capability, and electrical resistivity measurements were used to investigate phase transformation phenomena and thermomechanical behavior of shape-memory titanium-nickel (TiNi) films. The mechanisms responsible for phase transformation in the nearly equiatomic TiNi films were revealed by heating and cooling the samples inside the TEM vacuum chamber. Insight into the deformation behavior of the TiNi films was obtained from the nanoindentation response at different temperatures. A transition from elastic-plastic to pseudoelastic deformation of the martensitic TiNi films was encountered during indentation and heating. In contrast to the traditional belief, the martensitic TiNi films exhibited a pseudoelastic behavior during nanoindentation within a specific temperature range. This unexpected behavior is interpreted in terms of the evolution of martensitic variants and changes in the mobility of the twinned structures in the martensitic TiNi films, observed with the TEM during in situ heating.

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In Situ Observation of the C49-to-C54 Phase Transformation in $\bf TiSi_{2}$ Thin Films by Transmission Electron Microscopy

Japanese Journal of Applied Physics ◽

10.1143/jjap.35.l479 ◽

1996 ◽

Vol 35 (Part 2, No. 4B) ◽

pp. L479-L481 ◽

Cited By ~ 3

Author(s):

Hiroyuki Tanaka ◽

Norio Hirashita ◽

Robert Sinclair

Keyword(s):

Electron Microscopy ◽

Thin Films ◽

Transmission Electron Microscopy ◽

Phase Transformation ◽

In Situ Observation ◽

Transmission Electron

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In-Situ High Resolution Transmission Electron Microscopy of Dynamic Events During the Amorphous to Crystalline Phase Transformation in Silicon

MRS Proceedings ◽

10.1557/proc-62-311 ◽

1985 ◽

Vol 62 ◽

Cited By ~ 2

Author(s):

M. A. Parker ◽

T. W. Sigmon ◽

R. Sinclair

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Phase Transformation ◽

Solid State ◽

High Resolution ◽

Elevated Temperatures ◽

Video Recording ◽

Dynamic Events ◽

Transmission Electron

ABSTRACTA technique has been developed which employs high resolution transmission electron microscopy (HRTEM) for the observation of the atomic mechanisms associated with solid state phase transformation as they occur at elevated temperatures. It consists of the annealing in-situ of cross-section transmission electron microscopy (TEM) specimens that have been favorably oriented for lattice fringe imaging and the video-recording of dynamic events as they occur in real-time. By means of this technique, we report the first video-recorded lattice images of crystallographic defect motion in silicon, viz. the motion of dislocations and stacking faults, as well as the first such images of the atomic mechanisms responsible for the amorphous to crystalline (a-c) phase transformation, viz. heterogeneous nucleation of crystal nuclei, coalescence of crystal nuclei by co-operative atomic processes, ledge motion at the growth interface, and normal growth in silicon. This technique holds great potential for the elucidation of the atomic mechanisms involved in reaction kinetics in the solid state.

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