Solution-processed metal halide perovskite semiconductors, such as CH3NH3PbI3, have exhibited remarkable performance in solar cells, despite having non-negligible density of defect states. A likely candidate is halide vacancies within the perovskite crystals, or the presence of metallic lead, both generated due to the imbalanced I/Pb stoichiometry which could evolve during crystallization. Here...

We present a study of the effects of non-stoichiometry, boron purity, wire diameter and post-synthesis treatment (etching and Mg distilling) on the temperature dependent resistance and resistivity of sintered MgB2 pellets and wire segments. Whereas the residual resistivity ratio (RRR) varies between RRR ≈ 4 to RRR ≥ 20 for different boron purity, it is only moderately affected by non-stoichiome...

The effect of composition on the ternary (NbCr2–TiCr2) C15 phase properties has been investigated, focusing upon the defect structure, elastic properties, and mechanical behavior. The C15 phase field is continuous between NbCr2–TiCr2, with a maximum phase field width of at least 7 at.% solubility. The defect mechanism is governed by anti-site constitutional defects for all alloys. Mechanically,...

The surface and bulk compositions of the mixed metal oxide CoxNi1−xO have been compared over the entire range of stoichiometry 0 ≤ x ≤ 1. The materials, which were formed as polycrystalline solid solutions, were shown to be well-ordered and homogeneous in the bulk, but tend to deviate in their surface composition for x 0.6. Auger and X-ray photoelectron spectroscopy gave comparable results and ...

The T center in silicon is a well-known carbon-based color that has been recently considered for quantum technology applications. Using first-principles computations, we show the excited state formed by defect-bound exciton made of localized defect occupied an electron to which hole bound. strong carbon $p$ character and reminiscent localization unpaired ethyl radical molecule. radiative lifeti...

Since chlorophyll fluorescence reflects the redox state of photosynthetic electron transport chain, monitoring of chlorophyll fluorescence has been successfully applied for the screening of photosynthesis-related genes. Here we report that the mutants having a defect in the regulation of photosystem stoichiometry could be identified through the simple comparison of the induction kinetics of chl...

Solubility limits and constitutional defects in Laves phase intermetallics are investigated with the C15 HfCo2 system. Several binary alloy compositions based on HfCo2 are characterized by optical and scanning electron microscopy (SEM), electron microprobe analysis (EPMA), X-ray diffraction (XRD), and density measurements. Rietveld refinements of XRD scans are used to determine lattice constant...

Defects in semiconductors can exhibit multiple charge states, which can be used for charge storage applications. Here we consider such charge storage in a series of oxygen deficient phases of TiO2, known as Magnéli phases. These Magnéli phases (TinO2n-1) present well-defined crystalline structures, i.e., their deviation from stoichiometry is accommodated by changes in space group as opposed to ...

The microscopic cause of conductivity in transparent conducting oxides like ZnO, In{2}O{3}, and SnO{2} is generally considered to be a point defect mechanism in the bulk, involving intrinsic lattice defects, extrinsic dopants, or unintentional impurities like hydrogen. We confirm here that the defect theory for O-vacancies can quantitatively account for the rather moderate conductivity and off-...

Single crystals of YBa2Cu30,, of various oxygen stoichiometries, were irradiated with 50 keV Kr' to create defect cascades similar to those resulting from fast neutron irradiation. Two-beam dark-field transmission electron microscopy in weak dynamic conditions was used to measure the defect cascade size distribution in the principal axes for four different oxygen stoichiometries, and high-resol...