P. Shen

TiCx–Ti2C nanocrystals and epitaxial graphene-based lamellae by pulsed laser ablation of bulk TiC in vacuum

Nonstoichiometric δ-TiCx, δ′/δ′′-Ti2C and 2-D turbostratic graphene-based lamellae were co-synthesized by pulsed laser ablation of bulk δ-TiC in a vacuum and characterized using X-ray diffraction, electron microscopy and optical spectroscopy. The predominant δ-TiCx occurred as submicron-sized particulates and nanocondensates with size dependent shapes (5 nm sphere vs. 10 and 15 nm cubo-octahedra), which tended to coalesce over well-developed (111) as a unit or impinged by the ~(001) vicinal surface to form a [10] tilt boundary. The minor Ti2C nanocondensates occurred as cubo-octahedra for the cubic δ′-phase and triangular plates with well-developed (0001), {102} and {10} faces for the trigonal δ′′-phase, which tended to coalesce over (0001) as a unit. The turbostratic graphene-based lamellae occurred as nanoribbons or an artificial epitaxy shell on δ-TiCx and δ′/δ′′-Ti2C to facilitate carbon vacancy diffusion. The present TiCx–Ti2C-graphene phase assembly with characteristic Raman modes sheds light on their natural dynamic occurrence in presolar settings. The bimodal UV-visible absorbances of this phase assembly in the form of nanoparticles may have potential photocatalytic and abrasive/lubricant applications.

The basal twin of α-Cr2O3 nanocondensates: occurrence and first-principles calculations

The α-Cr2O3 nanocondensates prepared by pulsed laser ablation were identified by transmission electron microscopy to have a coherent basal twin boundary and well-developed (0001) and (10) surfaces. The cause of such a basal twin with a Burgers vector = 1/3[10] can be rationalized by the (0001)-specific rotation/coalescence of the crystalline nanocondensates to form a 2-D coincidence site lattice with an excess energy of 13 eV nm−2 according to first-principles density functional calculations. The unification/twinning bifurcation of the sesquioxide atom clusters that were previously coalesced can be explained by the critical particle size and the temperature for anchorage release at the interface.

Spontaneous bending of the coalesced α-Cr2O3 nanocondensates: implications for multilayer coating systems

Nanosized α-Cr2O3 bicrystals with a special boundary of mixed planes via (hkil)-specific coalescence were formed by pulsed laser ablation on Cr in oxygen atmosphere. Transmission electron microscopy observations indicated that the bicrystals consist of rhombic (denoted as r) and platy (denoted as p) parts with well-developed

On the precipitation of coherent spinel nanoparticles in Ti-doped MgO

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Shape-dependent local internal stress of α-Cr2O3 nanocrystal fabricated by pulsed laser ablation

//(0001)p interface and exact

On the spinel precipitation in Al-doped Ni1-xO

\left[ {{\bar{\text{2}}\text{2}}0\bar{1}} \right]_{\text{r}} //\left[ {{\bar{\text{1}}\text{1}}00} \right]_{\text{p}}