Facile synthesis of mixed phase 1T/2H-MoS heterostructured nanosheets with a highly efficient solar light-driven photocatalyst and recyclable adsorbent.

We report on facile hydrothermal synthesis of 2H and 1T/2H mixed-phase MoS nanosheets using different organic sulfur precursors with varying sulfur release tendencies. 1T/2H MoS demonstrated direct solar light-driven photocatalysis and adsorption recyclability, attributed to phase synergy and improved charge separation.

Crystallization Instead of Amorphization in Collision Cascades in Gallium Oxide.

Disordering of solids often leads to amorphization, but polymorph transitions, facilitated by favorable atomic rearrangements, may temporarily help to maintain long-range periodicity in the solid state. In far-from-equilibrium situations, such as atomic collision cascades, these rearrangements may not necessarily follow a thermodynamically gainful path, but may be kinetically limited. In this Letter, we focus on such crystallization instead of amorphization in collision cascades in gallium oxide (Ga_{2}O_{3}).

Phase glides and self-organization of atomically abrupt interfaces out of stochastic disorder in α-GaO.

Disorder-induced ordering and remarkably high radiation tolerance in γ-phase of gallium oxide is a recent spectacular discovery at the intersection of the fundamental physics and electronic applications. Importantly, by far, these data were collected with initial samples in form of the thermodynamically stable β-phase of this material. Here, we investigate these phenomena starting from metastable α-phase and explain radically new trend occurring in the system.

Self-Assembling of Multilayered Polymorphs with Ion Beams.

Polymorphism determines significant variations in materials' properties by lattice symmetry variation. If they are stacked together into multilayers, polymorphs may work as an alternative approach to the sequential deposition of layers with different chemical compositions. However, selective polymorph crystallization during conventional thin film synthesis is not trivial; changes of temperature or pressure when switching from one polymorph to another during synthesis may cause degradation of the structural quality.

Nature of Disordering in γ-Ga_{2}O_{3}.

Polymorphs commonly exist for various materials, enabling phase engineering for diverse material properties. While the crystal structures of different polymorphs can, in principle, be experimentally characterized, interpreting and understanding complex crystal structures can be very challenging. Using Ga_{2}O_{3} as a prototype, here we show that the crystal structure of γ-Ga_{2}O_{3} has long been misinterpreted from either theory or experiment.

Impact of Annealing in Various Atmospheres on Characteristics of Tin-Doped Indium Oxide Layers towards Thermoelectric Applications.

The aim of this work was to investigate the possibility of modifying the physical properties of indium tin oxide (ITO) layers by annealing them in different atmospheres and temperatures. Samples were annealed in vacuum, air, oxygen, nitrogen, carbon dioxide and a mixture of nitrogen with hydrogen (NHM) at temperatures from 200 °C to 400 °C. Annealing impact on the crystal structure, optical, electrical, thermal and thermoelectric properties was examined.

Standalone Highly Efficient Graphene Oxide as an Emerging Visible Light-Driven Photocatalyst and Recyclable Adsorbent for the Sustainable Removal of Organic Pollutants.

Carbon-based nanostructures are promising eco-friendly multifunctional nanomaterials because of their tunable surface and optoelectronic properties for a variety of energy and environmental applications. The present study focuses on the synthesis of graphene oxide (GO) with particular emphasis on engineering its surface and optical properties for making it an excellent adsorbent as well as a visible light-active photocatalyst. It was achieved by modifying the improved Hummers method through optimizing the synthesis parameters involved in the oxidation process.

Universal radiation tolerant semiconductor.

Radiation tolerance is determined as the ability of crystalline materials to withstand the accumulation of the radiation induced disorder. Nevertheless, for sufficiently high fluences, in all by far known semiconductors it ends up with either very high disorder levels or amorphization. Here we show that gamma/beta (γ/β) double polymorph GaO structures exhibit remarkably high radiation tolerance.

Interplay of the disorder and strain in gallium oxide.

Ion irradiation is a powerful tool to tune properties of semiconductors and, in particular, of gallium oxide (GaO) which is a promising ultra-wide bandgap semiconductor exhibiting phase instability for high enough strain/disorder levels. In the present paper we observed an interesting interplay between the disorder and strain in monoclinic β-GaO single crystals by comparing atomic and cluster ion irradiations as well as atomic ions co-implants. The results obtained by a combination of the channeling technique, X-ray diffraction and theoretical calculations show that the disorder accumulation in β-GaO exhibits superlinear behavior as a function of the collision cascade density.

Identification and Suppression of Majority Surface States in the Dry-Etched β-GaO.

Surface treatment after dry etching is vital to enhance the surface quality of the material and thus improve device performance. In this Letter, we identified the majority surface states induced by the dry etching of β-GaO and optimized surface treatments to suppress these electrically active defects with the improved performance of Schottky barrier diodes. Transient spectroscopies suggested that the majority traps (-0.

Yogic agnisara increases blood flow in the superior mesenteric artery.

Objectives: Medieval yoga texts claim that a special exercise of the muscles of the anterior abdominal wall, called agnisara, improves digestive function. Main objective of the study was to demonstrate change in the blood flow through superior mesenteric artery (if any) after performance of agnisara.

Methods: Ultrasound examination of the linear and volumetric indicators of blood flow in the superior mesenteric artery (SMA) before and after performing the agnisara yoga exercise 100 times was carried out in 12 healthy volunteers of both sexes (8 of them women).

Disorder-Induced Ordering in Gallium Oxide Polymorphs.

Polymorphs are common in nature and can be stabilized by applying external pressure in materials. The pressure and strain can also be induced by the gradually accumulated radiation disorder. However, in semiconductors, the radiation disorder accumulation typically results in the amorphization instead of engaging polymorphism.

Formation of N bubbles along grain boundaries in (ZnO)(GaN): nanoscale STEM-EELS studies.

Direct evidence of N formation after annealing of (ZnO)(GaN) alloys was revealed. N was trapped by V-clusters, forming faceted voids along grain boundaries. This study shows that N-N bonding is a competitive path for nitrogen after annealing, in addition to the increasing Ga-N bonds, indicating that N in O substitution sites (N) is not a stable configuration.

Role of Nitrogen in Defect Evolution in Zinc Oxide: STEM-EELS Nanoscale Investigations.

Direct evidence of the formation of nitrogen molecules (N) after ion implantion of ZnO has been revealed by an atomically resolved scanning transmission electron microscopy (STEM)-electron energy-loss spectroscopy (EELS) investigation. Taking advantage of the possibility of using multiple detectors simultaneously in aberration-corrected STEM, we utilize the detailed correlation between the atomic structure and chemical identification to develop a model explaining the formation and evolution of different defect types and their interaction with N. In particular, the formation of zinc vacancy (V) clusters filled with N after heat treatment at 650 °C was observed, clearly indicating that N has not been stabilized in the O substitution site, thus limiting p-type doping.

Band gap maps beyond the delocalization limit: correlation between optical band gaps and plasmon energies at the nanoscale.

Recent progresses in nanoscale semiconductor technology have heightened the need for measurements of band gaps with high spatial resolution. Band gap mapping can be performed through a combination of probe-corrected scanning transmission electron microscopy (STEM) and monochromated electron energy-loss spectroscopy (EELS), but are rare owing to the complexity of the experiments and the data analysis. Furthermore, although this method is far superior in terms of spatial resolution to any other techniques, it is still fundamentally resolution-limited due to inelastic delocalization of the EELS signal.

Micro-structured inverted pyramid texturization of Si inspired by self-assembled Cu nanoparticles.

A superior micron-sized inverted pyramid structure has been successfully achieved by one-step copper nanoparticles assisted chemical etching in Si/Cu(NO)/HF/HO solution for light trapping in silicon solar cells. The detailed mechanisms of such a novel method have been systematically demonstrated. The charge transfer during the reaction has been revealed by the simplified energy band diagram of the system as well.

Interface Engineering of High Efficiency Organic-Silicon Heterojunction Solar Cells.

Insufficient interface conformity is a challenge faced in hybrid organic-silicon heterojunction solar cells because of using conventional pyramid antireflection texturing provoking the porosity of interface. In this study, we tested alternative textures, in particular rounded pyramids and inverted pyramids to compare the performance. It was remarkably improved delivering 7.

Fluorine doping: a feasible solution to enhancing the conductivity of high-resistance wide bandgap Mg0.51Zn0.49O active components.

N-type doping of high-resistance wide bandgap semiconductors, wurtzite high-Mg-content MgxZn1-xO for instance, has always been a fundamental application-motivated research issue. Herein, we report a solution to enhancing the conductivity of high-resistance Mg0.51Zn0.

Maskless inverted pyramid texturization of silicon.

We discovered a technical solution of such outstanding importance that it can trigger new approaches in silicon wet etching processing and, in particular, photovoltaic cell manufacturing. The so called inverted pyramid arrays, outperforming conventional pyramid textures and black silicon because of their superior light-trapping and structure characteristics, can currently only be achieved using more complex techniques involving lithography, laser processing, etc. Importantly, our data demonstrate a feasibility of inverted pyramidal texturization of silicon by maskless Cu-nanoparticles assisted etching in Cu(NO3)2 / HF / H2O2 / H2O solutions and as such may have significant impacts on communities of fellow researchers and industrialists.

Probing defects in nitrogen-doped Cu2O.

Nitrogen doping is a promising method of engineering the electronic structure of a metal oxide to modify its optical and electrical properties; however, the doping effect strongly depends on the types of defects introduced. Herein, we report a comparative study of nitrogen-doping-induced defects in Cu2O. Even in the lightly doped samples, a considerable number of nitrogen interstitials (Ni) formed, accompanied by nitrogen substitutions (NO) and oxygen vacancies (VO).

Influence of graphene synthesizing techniques on the photocatalytic performance of graphene-TiO2 nanocomposites.

Model photocatalysts composed of TiO2-graphene nanocomposites are prepared to address the effect of graphene quality on their photocatalytic performance. Graphene is synthesized by catalyst-assisted chemical vapor deposition (CVD), catalyst-free CVD and solution processing methods. TiO2 is prepared by reactive magnetron sputtering and subsequent annealing.

Intrinsic point-defect balance in self-ion-implanted ZnO.

The role of excess intrinsic atoms for residual point defect balance has been discriminated by implanting Zn or O ions into Li-containing ZnO and monitoring Li redistribution and electrical resistivity after postimplant anneals. Strongly Li-depleted regions were detected in the Zn-implanted samples at depths beyond the projected range (R(p)) upon annealing ≥ 600 °C, correlating with a resistivity decrease. In contrast, similar anneals of the O-implanted samples resulted in Li accumulation at R(p) and an increased resistivity.

Nanostructure formation and passivation of large-area black silicon for solar cell applications.

Nanoscale textured silicon and its passivation are explored by simple low-cost metal-assisted chemical etching and thermal oxidation, and large-area black silicon was fabricated both on single-crystalline Si and multicrystalline Si for solar cell applications. When the Si surface was etched by HF/AgNO(3) solution for 4 or 5 min, nanopores formed in the Si surface, 50-100 nm in diameter and 200-300 nm deep. The nanoscale textured silicon surface turns into an effective medium with a gradually varying refractive index, which leads to the low reflectivity and black appearance of the samples.