In-grown vacancy defects in bulk and quasi-bulk GaN crystals have been extensively studied with positron annihilation spectroscopy. High concentrations of Ga-vacancy-related are found irrespective the growth method used a high O contamination or intentional doping, they act as dominant compensating native defect for n-type conductivity. Low-temperature crystal also leads to defects. Ga vacancie...

Photoelectron spectroscopy and ab initio calculations have been carried out to probe the structures and chemical bonding of the B27 (-) cluster. Comparison between the experimental spectrum and the theoretical results reveals a two-dimensional (2D) global minimum with a triangular lattice containing a tetragonal defect (I) and two low-lying 2D isomers (II and III), each with a hexagonal vacancy...

In the present work, we use reverse non-equilibrium molecular dynamics with adaptive intermolecular reactive empirical bond order interatomic potential to investigate sensitivity of thermal conductivity in (6, 6) single-walled carbon nanotubes (SWCNTs) to side-wall defects and high temperature heat-treatment. Effects of two side-wall defect types and their concentrations are evaluated: chemisor...

In this paper, we report the synthesis of tin oxide (SnO2) nanoparticles by co-precipitation technique. The structural, surface morphology, thermal and optical properties of the SnO2 samples were analysed using X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM), Fourier transformed infrared (FTIR) spectrum, thermo gravimetric analysis (TGA/DT...

Nickel is a common impurity in high-pressure high-temperature diamond and may contaminate chemical vapor deposited used for high-power electronics or quantum technology applications. Magneto-optical fingerprints of nickel have been known since decades, however, no consensus has reached about the microscopic origins nickel-related electron paramagnetic resonance, photoluminescence, optically det...

We have used classical molecular dynamics based on the Brenner potential describing carbon-carbon covalent bonds to study the melting point and vacancy movement in a rectangular graphene nanoribbon. The melting point of the graphene nanoribbon extracted from the numerical simulation is ~3400 K. We also found that two separated vacancies at high temperature (e.g., ~3000 K, below the melting poin...

One-to-one comparisons between indentation experiments and atomistic modelling have until recently been hampered by the discrepancy in length scales of the two approaches. Here, we review progress in atomic-scale nanoindentation experiments employing scanning probe techniques to achieve depth-sensing indentation and field ion microscopy to permit detailed indenter characterization. This perspec...

We present a brief review of recent advances in the atomistic modeling of segregation and precipitation kinetics in iron-chromium alloys, during thermal ageing and under irradiation. The approach takes into account the real diffusion mechanisms: vacancy and, under irradiation, self-interstitial jumps. Migration barriers are computed with effective pair interactions fitted on ab initio calculati...

Engineering single atomic defects into wide bandgap materials has become an attractive field in recent years due to emerging applications such as solid-state quantum bits and sensors. The simplest atomic-scale defect is the lattice vacancy which often a constituent part of more complex nitrogen-vacancy (NV) centre diamond, therefore understanding formation mechanisms precision engineering vacan...