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Abstract Dislocations originating from the seed junctions are the most harmful defects in quasi-single crystalline silicon (QSC-Si). In traditional <100>-oriented QSC-Si ingots, dislocations easily develop into cascade shape, or even further form sub-grain boundaries as the ingot grows. In this paper, we have developed a novel <110>-oriented QSC-Si ingot to control the gliding and propagation of dislocations. It is found that the cascade shape is absent and dislocations only aggregate in the {100}/{100} boundary planes of <110>-oriented seeds, revealed by the minority carrier lifetime mapping and photoluminescence image. Accordingly, the internal quantum efficiency of <110>-oriented QSC-Si solar cells is obviously higher than that of the traditional <100>-oriented ones. Nevertheless, it should be noticed that the average photoelectric conversion efficiency of <110>-oriented QSC-Si solar cells could be 0.6% lower than that of traditional ones if the {100}/{100} boundary is included in the solar cell, due to a higher reverse leakage current. This problem can be involved by enlarging the size of seed crystals or adopting better seed arrangement. These results provide a new promising method for the development of high quality QSC-Si in photovoltaic industry. Highlights • The quasi-single crystalline silicon is grown by using <110>-oriented seeds. • The dislocations originating from the seed junctions are confined at the junctions of the {100}/{100} boundary plane. • The gliding and propagation of dislocations in the <110>-oriented QSC-Si ingot are completely controlled. • The average minority carrier lifetime of the <110>-oriented QSC-Si ingot is significantly increased. [ABSTRACT FROM AUTHOR]

Abstract Thin films of GdFeO 3 (GdFO) have been grown on two (00 l) oriented single crystal substrates viz., LaAlO 3 and SrTiO 3 using pulsed laser ablation method. Phase purity of the prepared samples is confirmed from x-ray 2 θ − ω measurements. From the x-ray phi-scans and reciprocal space mapping measurements, it is observed that GdFO films are epitaxial and grow in (00 l) out-of-plane orientation. It is observed that the GdFO grows along the diagonal of the substrate cube with in-plane 90 o rotated orthorhombic twins for both the substrates. Magnetization data shows the signatures of Gd 3+ ordering and magnetic field induced spin re-orientation similar to that of bulk GdFO for both the substrates. However, surface morphology is found to be different for both the substrates resulting in considerable changes of O K -edge near absorption spectra. Highlights • Growth of GdFeO3 film with laser ablation on SrTiO3 & LaAlO3 substrate is reported. • Films grow epitaxially on both the substrates with two in-plane 90o domains. • Enhanced covalent mixing between O-2 p and Fe-3 d (t 2g) orbitals is observed. [ABSTRACT FROM AUTHOR]

We study systematically the nanocutting of an Fe single crystal in dependence of the surface orientation and cut direction. We find that in the general case – where the edge dislocations formed at the cutting edge glide obliquely to it – a complex, three-dimensional dislocation network is created. If, however, the edge dislocations formed align with the cutting edge direction, then a simple (two-dimensional) cutting mechanism is realized, in which dislocations glide consecutively without interaction. The shape of the chip is governed by the direction of the activated glide systems. For strong dislocation interaction, a grain boundary may form separating the chip from the workpiece. A cutting hardness is defined; the calculated values are in good agreement with the ploughing hardness measured in scratching simulations. For selected orientations, we find that instead of dislocation plasticity, twinning is activated. This requires smaller cutting forces and the created chip surfaces are smooth. [ABSTRACT FROM AUTHOR]

Orientation related phase transitions of 0.76Pb(Mg 1/3 Nb 2/3 )O 3 -0.24PbTiO 3 single crystals are studied. Values of the relaxation parameters ( γ = 1.87–1.97) estimated from linear fits of the modified Curie-Weiss law indicate the relaxor nature. For (110) oriented single crystal, typical oxygen vacancies related high temperature dielectric relaxation behaviors are observed and analyzed. Orientations dependent electrocaloric effects of 0.76Pb(Mg 1/3 Nb 2/3 )O 3 -0.24PbTiO 3 single crystals are first studied and reported, large reversible adiabatic temperature change (0.80 K) and isothermal entropy change (0.66 J K −1 kg −1 ) are observed. Giant refrigeration efficiency (43.52) and high electrocaloric coefficient (0.041 K cm kV −1 ) exceed the electrocaloric effect values in most bulk ferroelectrics in previous reports. [ABSTRACT FROM AUTHOR]

Highly uniform and conductive single crystals of poly(3-hexylthiophene) (P3HT)-based homo and block copolymers with the end coily blocks of polystyrene, poly(methyl methacrylate), and poly(ethylene glycol) are developed using self-seeding method from varied quality solvents. Edge-on and flat-on orientations are detected depending on the thickness and width of single crystals. Coily blocks are excluded from the P3HT crystalline structures, leading to brush-like or hairy regions on surface of grown single crystals in the longitude of P3HT chains. The larger single crystals possessing flat-on orientation are obtained from weaker solvents at higher seeding temperatures. The longer P3HT chains are folded, however, the shorter backbones are laminated on each other. The highest backbone lamination occurs for homo-P3HT7150 ( Mn of P3HT = 7150 g mol−1) single crystals grown at 20 °C from anisole, the weakest employed solvent. In contract, highly ordered and folded hairy single crystals are acquired from better solvents and high molecular weight P3HTs. In these conditions, the crystallographic features of the hairy block copolymer single crystals are similar to those of nonhairy homo-P3HT ones. The coily brush-covered P3HT48 800 single crystals have more foldings compared to the homo-P3HT48 800 ones, whereas only two laminated backbones in shorter P3HT blocks are detected. [ABSTRACT FROM AUTHOR]

Amechanism of local formation of crystals of random orientation in growth of single-crystal billets of refractory nickel alloys for blades of gas turbine engines is suggested. Aturn of the lattice is initiated at the place of contact between the initial melt and the surface of hard particles of NbC carbide and/or TiN nitride. [ABSTRACT FROM AUTHOR]

Single crystalline and textured In 2 O 3 thin films with (1 1 1) surface orientation, grown by plasma-assisted molecular beam epitaxy, were used as a model system to study the role of bulk and surface electron accumulation layer conductance for ozone sensing. Both conductance contributions, which add to the total film conductance, were systematically varied. The resulting ozone sensitivity was determined by total conductance measurements in synthetic air with defined ozone concentration using UV irradiation instead of heating to regenerate the In 2 O 3 surface. Depletion of the surface electron accumulation by an oxygen plasma treatment, confirmed by X-ray photoelectron spectroscopy, rendered the films ozone insensitive. The ozone response of films with an accumulation layer was increased by thickness reduction or by designing the bulk of the film semi-insulating using deep acceptor doping by Mg. Our results of using electron accumulation layers for gas sensing and bulk doping by deep acceptors to increase sensitivity can be generalized to other gas sensing materials. The use of single crystalline films allows selecting the most sensitive crystallographic surface orientation and may have further advantages over polycrystalline films, such as increased stability and sensing speed. [ABSTRACT FROM AUTHOR]

By the local electroreflectance method the topographic analysis of Ge1-x Six monocrystal surface was performed. The influence of the surface orientation on defects density distribution was found. Topographic maps of the defectiveness distribution on the crystal surfaces with (111) and (110) orientations were constructed and visualized. [ABSTRACT FROM AUTHOR]

The mechanical behavior of single crystal Al sample with different sizes in mini-, micro- and nano-scales and different loading directions along [111] and [110] have been systematically investigated. The sample size and orientation effects are examined. The results are compared with previously reported data on other face-centered cubic Ni, Cu, Au and Ag, establishing an interesting trend for sample size effect with respect to stacking fault energy. With higher stacking fault energy and thus higher dislocation mobility such as Al, the sample size dependence would be lower. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations of nanoindentation are used to study the deformation behaviors of single crystal Zr for four different surface orientations. The comparison of results for two different potentials, an embedded atom method potential and a charged optimized many body potential, reveals the influence of stable and unstable stacking fault energy on dislocation behaviors under nanoindentation. The load–displacement curve, hardness and deformation behaviors of the various surface orientations Zr are compared and the elastic and plastic deformation behaviors are analyzed. [ABSTRACT FROM AUTHOR]

The phenomenon of restrained stress-induced preferential orientation of S′ precipitates is investigated using a single-crystal of Al–1.23Cu–0.43 Mg alloy. Al–1.23Cu–0.43 Mg single-crystal specimens are subjected to stress aging, and the microstructure is analyzed by transmission electron microscopy (TEM). It is found that the stress-induced preferential orientation of S′ precipitates is restrained owing to the dislocations produced by a higher stress. The effect of dislocations on the oriented precipitates depends on the total length of the intersection lines for precipitate habit planes and dislocation glide planes. This investigation not only provides important insight into solving the anisotropy problem attributed to precipitation strengthening, but also offers a benchmark for choosing the appropriate stress range in manufacturing of Al–Cu–Mg alloys. [ABSTRACT FROM AUTHOR]

Tensile behavior of the nickel-base single-crystal superalloy DD6 was studied from room temperature to 1020 °C. The plate specimens were along [001] orientation parallel to the loading axis in tension. The microstructures on the surface and fracture morphology were investigated after tensile test to rupture by scanning electron microscopy (SEM). The results of the present investigation indicate that the yield strength at 650 °C is superior to that at room temperature, 850 °C and 1020 °C. Low ductility and serrated flow in stress–strain curves were also observed at 650 °C. The microstructures on the surface of the plate specimens and fracture morphology observation indicated that localized slip which resulted in glide plane decohesion caused the low ductility of DD6 alloy. [ABSTRACT FROM AUTHOR]

We present the orientation dependent indentation response of pure magnesium during single grain indentation. A conical indenter and maximum loads between 50 mN and 900 mN were employed. Indent topographies were acquired by confocal microscopy. The indents were also characterized by electron backscatter orientation microscopy for their microstructures. Pronounced activation of specific twinning systems was observed around the impressions. The resulting data were compiled into the inverse pole figure presentation of indent microstructures and topographies after Zambaldi and Raabe, Acta Mater. (2010). Three-dimensional crystal plasticity finite element simulation of the indentation deformation supports the interpretation of the orientation dependent slip and twinning patterns around the indents. The match between the activation of observed and simulated twinning variants is discussed with respect to the conditions for nucleation and growth of extension twins. Furthermore, the compatibility of the twinning strains with the imposed deformation is discussed based on the expanding cavity model of indentation. The orientation dependent response of magnesium during indentation is compared to the literature data for indentation of alpha-titanium and beryllium. Recommendations are given on how to exploit the characteristic nature of the observed indentation patterns to rapidly assess the relative activity of deformation mechanisms and their critical shear stresses during alloy development. [ABSTRACT FROM AUTHOR]

The early stages of recrystallization have been systematically characterized in single crystal metals of medium and low stacking fault energy. Goss {1 1 0}〈0 0 1〉 and brass {1 1 0}〈1 1 2〉 oriented samples of Ni, Cu and Cu–2 wt.% Al alloy were deformed in a channel die to a logarithmic strain of 0.51 to develop a homogeneous structure composed of two sets of symmetrical primary microbands and then lightly annealed. Scanning electron microscopy/electron backscattered diffraction analyses demonstrate a strong relation between as-deformed orientations and the limited number of recrystallized grain orientations. The disorientation angles across the recrystallization front are mostly grouped in the ranges of 25–35° and 45–55° around axes located near, but not at, the normals of all four {1 1 1} planes. The original nuclei possess disorientation angles of 25–35°. The orientation of the growing new grain quickly transforms through the formation of a first generation twin, leading to disorientations of 45–55°. The most frequent situation occurs when the normal of the twinning face plane is situated near the rotation axis, around which the crystal lattice of the “primary nuclei” rotates. Based on the anisotropy of grain growth, a possible mechanism of orientation generation and grain growth by thermally activated movement of dislocation families on {1 1 1} planes is proposed. [ABSTRACT FROM AUTHOR]

This study reports a direct observation on the crack behavior of lithiated Si wafer. Three different Si wafers with <100>, <110> and <111> axes are investigated, to compare the crack behaviors of different orientation Si wafers. Electrochemically induced cracks in each orientated wafer have dissimilar crack behaviors, because the initiations and propagations of cracks are strongly affected by their orientation and strain energy release rate. It is also found that triangular humps and cracks are formed in the (111) wafer, which are discovered for the first time by in this study. Considering that volume expansion, cracks, and pulverizations of Si are the main issues for the commercial use of Si for Li ion battery, this study provides important insight that is relevant to the design of advanced Si anode materials. [ABSTRACT FROM AUTHOR]

The magnetic structure of a quasi-one-dimensional frustrated NaCuO magnet single crystal is studied by NMR. The spatial orientation of the planar spin spirals in the copper-oxygen Cu-O chains is determined, and its evolution as a function of the applied magnetic field direction is analyzed. [ABSTRACT FROM AUTHOR]

Fabrication of high‐quality organic single‐crystalline semiconductors and their deterministic patterning are core opportunities as well as challenges for large‐scale integration of functional devices with high efficiency and boosted performance. Previous approaches on solution patterning of organic semiconductors have achieved efficient and versatile control of the position, alignment, and size of organic structures. However, the poorly controllable dewetting dynamics of organic solution gives rise to low crystallinity and disordered crystallographic orientation of generated organic architectures that limit their device performance. Here, 1D organic single‐crystal arrays with high crystallinity, strict crystallographic alignment, precise position, tunable, and homogeneous size are fabricated by exploiting an asymmetric‐wettability topographical template. Periodically arranged micropillars with lyophobic sidewalls and lyophilic tops permit the generation of capillary bridges, which enable unidirectional dewetting of organic solution and ordered packing of molecules. The 1D arrays present pure (100) crystallographic orientation with π–π stacking of molecules in the optimal direction of carrier transport, leading to high carrier mobility of 8.7 cm2 V−1 s−1 in the field‐effect transistor measurements. A facile pressure sensor based on the patterned belt arrays is fabricated, exhibiting high sensitivity and long‐term stability. Organic single crystals with high alignment and pure crystallographic orientation are patterned by exploiting an asymmetric‐wettability topographical template. The high carrier mobility reaches 8.7 cm2 V−1 s−1 in field‐effect transistor measurements. Pressure sensors based on it exhibit high sensitivity and durability. [ABSTRACT FROM AUTHOR]