Single Crystal Rods Research Articles

Interaction of Y and impurity P on the synergistic enhancement of elongation and electrical conductivity of single crystal copper rod

Single-crystal copper rods with high conductivity and mechanical properties are the decisive material for the production of microwires for chip bonding. To further improve the product of strength and elongation as well as electrical conductivity, rare earth Y is added to a single-crystal copper rod to adjust the microstructure and impurity state. The results show that Cu-0.03Y copper rods have excellent comprehensive properties. The electrical conductivity improves to 103.72 % IACS, and the product of strength and elongation improves to 8.772 GPa%. The precipitates in the Cu-0.03Y single crystal copper rod are nano-sized spherical particles composed of YP (NaCl type) and Cu5Y (Cu5Ca type) phases. The enthalpy of formation of Y and P is calculated using Miedema thermodynamics as ΔH = −173.45 kJ·mol−1. The precipitates formed by the preferential reaction of Y and P reduce the solid dissolved atoms in the copper, and the electrical conductivity increases accordingly. The 〈001〉 texture of a single-crystal copper rod decreases with the addition of Y, while the 〈101〉 texture increases with good plasticity, leading to an improvement in elongation.

Novel Piezo-active 2–1–2 Composites with Sets of Large Hydrostatic Parameters

A 2–1–2 composite with two single-crystal components is studied for the first time to highlight large hydrostatic piezoelectric coefficients dh * and gh *, figure of merit dh *gh *, and electromechanical coupling factor kh *. Each 2–1–2 composite contains layers of domain-engineered [011]-poled relaxor-ferroelectric (1–x)Pb(Zn1/3Nb2/3)O3 – xPbTiO3 single crystal (x = 0.0475–0.09) and heterogeneous layers being systems of aligned piezoelectric Li2B4O7 single crystal rods in polyethylene, and these rods have an elliptic cylindrical shape. New diagrams show the volume-fraction ranges wherein large values of dh *> 10−9 C/N, dh *gh *> 2.10−10 Pa−1 and kh *≈ 0.5–0.6 are observed.

Novel lead-free 2–1–2 composite: predicted high piezoelectric sensitivity and significant hydrostatic response

A parallel-connected composite with 2–1–2 connectivity and two lead-free single-crystal (SC) components is proposed. Its high piezoelectric sensitivity is highlighted and its large hydrostatic parameters are described. The first type of composite layer represents a ferroelectric domain-engineered [001]-poled [Li, (K, Na)](Nb, Ta)O3 SC. In the second type of composite layer, piezoelectric Li2B4O7 SC rods in the form of an elliptic cylinder are regularly aligned in a large polymer matrix. The effective electromechanical properties of the composite were found in three stages, using the effective field and matrix methods that are applicable to piezoelectric media. A new orientation effect was studied, linked with rotations of SC rod bases in the polymer medium that forms the second type of layer. Since these rotations are in a Li2B4O7 SC with a unique elastic and piezoelectric anisotropy, the second type of layer exhibits a noticeable influence on the piezoelectric performance and hydrostatic response of the composite. A variation of the aspect ratio of the Li2B4O7 rod base becomes another important factor that can improve the hydrostatic parameters of the composite. Some effective parameters of related 2–1–2 composites were compared for different polymer components. Three diagrams were first constructed for the high-performance 2–1–2 [Li, (K, Na)](Nb, Ta)O3/Li2B4O7/polyethylene composite to show the ranges of rotation angles and volume fractions that correspond to the longitudinal piezoelectric voltage coefficient > 500 mV m N−1, hydrostatic piezoelectric coefficient > 200 mVm N−1 and hydrostatic figure of merit >10−11 Pa−1. These effective parameters are important in piezoelectric sensors and hydroacoustic and other applications of novel lead-free composites.

Texture evolution and its influence mechanism on properties of single crystal copper and polycrystalline copper during cumulative deformation

The φ16 mm single crystal copper rod was prepared by heated-mold horizontal continuous casting, and the φ16 mm polycrystalline copper rod was prepared by up-casting technology. Both of them were drawn to φ0.2 mm, the conductivity, strength, elongation, and microstructure evolution of single-crystal copper wire and polycrystal copper wire were compared and analyzed. The results show that the plasticity of as-cast single-crystal copper rod is 13.94% higher than that of as-cast polycrystalline copper rod. When drawing to φ0.2 mm, a single crystal copper wire with high strength (506 MPa) and high conductivity (98.01% IACS). At the same deformation amount, the single crystal copper wire obviously deforms more slowly and has a higher plastic deformation capacity; the texture transformation of single crystal copper wire is from soft → hard orientation, selective orientation to discrete distribution, while the weave transformation of polycrystalline copper wire is from soft → hard orientation, then from hard → soft orientation, and finally stabilizes to selective orientation. The microstructural evolution of single-crystal copper wire and polycrystalline copper wire during continuous deformation was observed: dislocation entanglement into dislocation cells by slip → microstrip structure → lamellar organization → twinning organization, single-crystal copper wire appears twinning later, single-crystal copper deformation coordination ability is better than polycrystalline copper. It is found that the increase of dislocation density, the decrease of grain width and the increase of <111> texture are the main factors for the strength improvement of micro-nano pure copper wires.

&lt;sup&gt;7&lt;/sup&gt;Li Diffusion in Thin Disks of Single-Crystal Garnet LLZO-Ta Studied by PFG-NMR Spectroscopy

Pulsed field-gradient (PFG) NMR spectroscopy was applied to thin disk samples (0.5, 1 and 2 mm thick, 4 mm diameter) of LLZO-Ta (Li&lt;sub&gt;6&lt;/sub&gt;La&lt;sub&gt;3&lt;/sub&gt;Zr&lt;sub&gt;1.5&lt;/sub&gt;Ta&lt;sub&gt;0.5&lt;/sub&gt;O&lt;sub&gt;12&lt;/sub&gt;) single crystal. We have measured the diffusion of &lt;sup&gt;7&lt;/sup&gt;Li in thin pellets (0.5 to 3 mm thick) of NASICON-type LAGP powder and found that the Li&lt;sup&gt;+&lt;/sup&gt; diffuses preferentially in the thicker direction. In this study, we placed 1 mm thick, 4 mm diameter disk-shaped single crystals vertically, i.e., parallel to the PFG direction. We found that &lt;sup&gt;7&lt;/sup&gt;Li ions diffuse similarly as in rod-shaped single crystals. The &lt;sup&gt;7&lt;/sup&gt;Li diffusion is slow (diffusion coefficient; ~2 × 10&lt;sup&gt;-13&lt;/sup&gt; m&lt;sup&gt;2&lt;/sup&gt;s&lt;sup&gt;-1&lt;/sup&gt;) at Δ ≥ 100 milliseconds and gradually becomes faster to ~1 × 10&lt;sup&gt;-11&lt;/sup&gt; m&lt;sup&gt;2&lt;/sup&gt;s&lt;sup&gt;-1&lt;/sup&gt; at Δ ≤ 10 milliseconds at 28°C. A diffraction pattern was observed in the echo decay plots, which was not observed in well-prepared single crystal rod samples. The diffraction patterns are often observed in powder inorganic electrolytes (LLZOs, LLTO, LAGP, and (Li&lt;sub&gt;2&lt;/sub&gt;S)&lt;sub&gt;x&lt;/sub&gt;(P&lt;sub&gt;2&lt;/sub&gt;S&lt;sub&gt;5&lt;/sub&gt;)&lt;sub&gt;y&lt;/sub&gt;). In this study, edge effects are assumed for the diffraction pattern of the vertically placed thin disk of the single crystal. For horizontally placed disks, at long observation times (Δ ≥ 100 milliseconds), the diffusion coefficients of &lt;sup&gt;7&lt;/sup&gt;Li agreed with those of the rod-shaped samples. However, as Δ became shorter, contrary to the vertically placed disk, the diffusion of &lt;sup&gt;7&lt;/sup&gt;Li decreased and the plots became less linear. Surprisingly, as Δ became shorter (Δ ≤ 15 milliseconds), sinusoidal patterns were observed in the real and imaginary elements of the echo attenuation plots,. The pattern is reproducible and the first example of sinusoidal real and imaginary components of the echo attenuation plot was observed, but an adequate explanation has not been obtained.

Growth of a Gradient-Doped Single-Crystal Rod with Designable Distribution of Doped Ions by a Laser-Heated Pedestal Growth Method

Growth of a Gradient-Doped Single-Crystal Rod with Designable Distribution of Doped Ions by a Laser-Heated Pedestal Growth Method

Two‐Stage Hybrid Optimization Algorithm for Silicon Single Crystal Batch Scheduling Problem under Fuzzy Processing Time

Considering the widely existing processing time uncertainty in the real‐world production process, this paper constructs a fuzzy mathematical model for the silicon single crystal production batch scheduling problem to minimize the maximum completion time. In this paper, a two‐stage hybrid optimization algorithm (TSHOA) is proposed for solving the scheduling model. Firstly, the improved differential evolution algorithm (IDE) is used to solve the order quantity allocation problem of silicon single crystal with different sizes to obtain the quantity of silicon single crystal rods with different sizes produced by different types of single crystal furnaces. Secondly, the variable neighborhood search (VNS) algorithm is adopted to optimize the order quantity sequencingof batch production processes. Finally, simulations and comparisons demonstrate the feasibility of the model and the effectiveness of TSHOA.

Enhancing removal of hydrogen from granular polysilicon by innovating vacuum separation model and method for SoG-Si

Silane process of granular polysilicon has become a promising method for the preparation of polysilicon due to its continuous low temperature, simple process and low energy consumption. However, granular silicon contains more hydrogen than conventional columnar silicon, which can result in the deterioration of single crystal furnace thermal field life and rod stability by the “hydrogen jump” in the process of Czochralski method. Hydrogen removal has become an important problem to be solved in the industry development. Thus, we propose a hydrogen separation model suitable for silicon system based on vacuum experiment and thermodynamic calculation, which can provide a theoretical basis for the research and development of silicon dehydrogenation method. The predicted removal rate of hydrogen at different temperatures and vacuum pressures is in good agreement with the experimental results, reflecting the reasonability of the model. The results show that the hydrogen removal rate increases with the increasing of temperature and the decreasing of pressure, where temperature plays a leading role in the removal of hydrogen in silicon. At less than one atmosphere, the increase in dehydrogenation rate by 1 °C ranges from 0.01% to 0.25% in the temperature range from 1450 to 1800°CAt temperatures below 1800°Cthe maximum dehydrogenation rate is less than 0.001% for each 1pa reduction in pressure from one atmospheric pressure to 1000pa. According to the model calculation results, a hydrogen removal method is designed by using the vacuum electromagnetic induction. The deep removal of trace hydrogen in silicon has been realized, hydrogen in silicon drops rapidly from around 20 ppm to less than 5 ppm.

Piezoelectric properties and related parameters of novel 1–2–2 composites based on single crystals of the PZN–xPT type

High-performance 1–2–2 composites based on domain-engineered relaxor-ferroelectric single crystals are analyzed, which demonstrate strong electromechanical coupling and large energy-harvesting characteristics. The role of the single-crystal rods and laminar polymer matrix is highlighted. A large anisotropy of the piezoelectric charge coefficients d 3j* and electromechanical coupling factors k 3j* is observed in specific volume-fraction ranges, with proposed dependence diagrams. The effective parameters of composites with parallelepiped-shaped rods are compared to similar parameters for composites based on cylindrical rods, with good agreement between parameters. These novel composites can be used in piezoelectric sensors, actuators, transducers, and energy-harvesting devices.

Effect of some hydroxyl additives on the growth and optical properties of KDP crystals

Potassium dihydrogen phosphate (KDP) single crystal was doped with disodium tetraborate decahydrate (or borax), L-alanine, and disodium ethylenediaminetetraacetate (or disodium EDTA) with 0.05 mol%, 9 mol%, and 2 mol% concentration in the aqueous solution, respectively. These crystals were fabricated by the temperature reduction method incorporating the Sankaranarayanan-Ramasamy technique and were grown onto seed crystals that were inclined at the type I phase-matching angle to the vertical. Each doped KDP single crystal rod was cut into three parts: the bottom, the middle, and the top, which were related to the fabrication temperature range of 50–40 °C, 40–30 °C, and 30–20 °C, respectively. The effect of the additives on the growth and optical properties of KDP crystals was evaluated through Ultraviolet–Visible spectroscopy, Raman spectroscopy, X-Ray Diffraction analysis, Energy-Dispersive X-ray spectroscopy, and Second Harmonic Generation measurement. The hydroxyl impurities have improved the optical properties of KDP crystals by contributing more hydrogen bonds to the KDP lattice. The doped KDP crystals increased SHG efficiency by 1.19 to 2.36 times compared with pure KDP crystals.

Evolution mechanism of crystallographic orientation in grain continuator bars of a Ni-based single-crystal superalloy prepared by Bridgman technology during directional solidification

Single-crystal rods with different diameters and deviation angles with respect to the solidification direction were produced by Bridgman rapid solidification method at withdrawal rates of 3 and 6 mm·min-1 and used as grain continuators. The crystallographic orientation of the rods, which cross-sections were perpendicular to the solidification direction at different solidification heights, was measured by electron backscattered diffraction, while the corresponding microstructures were observed by optical microscopy. The mushy zone morphology and the distribution of the temperature gradient were simulated by the finite element analysis software ProCAST. The experimental results indicate that the crystallographic orientation of the single-crystal rods corresponds to the statistical average value of all the dendrite orientations in cross-section. The crystallographic orientation of the primary and secondary dendrites of each single-crystal rod at different cross-sections fluctuates irregularly within a small range (less than 4°). The crystallographic orientation of the dendrite in each single-crystal rod is not exactly consistent with each other and is affected by their branching mode of dendrites in the solidification space. In addition, the simulation results show that the mushy zone shapes and the temperature gradient of single-crystal rods change with the increase of solidification height during the solidification process. Finally, the evolution mechanism of the crystallographic orientations and the corresponding influence factors were analyzed and discussed.

Demonstrated gradual evolution of disorder in crystalline structures between single crystal and polycrystal via chemical and physicochemical approaches

Single-crystal fluorapatite rods elongated in the c direction are switched to iso-oriented nanorods by adding a specific carboxy compound (chemical approach) and to roughly arranged nanograins by increasing the supersaturation at the growth front (physicochemical approach).

On the distribution of the atomic planes in an elastic single-crystal bar under the action of volumetric forces

A theoretical study of the behaviour of atomic planes in an elastic single-crystal rod under the action of volumetric forces such as the inertial force and the force of gravity has been carried out. The regularity of the linear distribution density of atomic planes in a single-crystal rod has been established in frames of continuous and discrete approaches. The obtained distribution function is of independent interest, and it can be used, for example, in studying the behaviour of a metal rod under conditions of an external induced electric field.

Microstructural Characterization of a Single Crystal Copper Rod Using Monochromatic Neutron Radiography Scan and Tomography: A Test Experiment

This paper reports the analysis of a single crystal copper rod aiming to characterize the microstructural features related to the homogeneity of the single crystal growth and the presence, shape and extension of spatially distributed misaligned grains or areas. The analytical method used for such analysis is wavelength scan neutron radiography and monochromatic neutron tomography. Such methods allow determination of the extent of differently oriented single crystal areas, identifying the most part of the rod volume as a single domain. It was also possible to characterize the spatial distribution and the degree of alignment of local point-like or extended defects.

Microstructure transformation of Mo–3Nb single crystal used for space thermionic reactor during welding

Mo–3Nb single crystal is an important material used for processing the emitter of space thermionic reactor. The present research focuses on the microstructures of precipitated phases in the Mo–3Nb matrix and the joint welded by the vacuum electron beam, to reveal the microstructural transformation during the welding process. Characterization of the precipitates was conducted by transmission electron microscopy (TEM) with energy dispersive spectrum (EDS). The results show that the precipitated phases in the Mo single crystal matrix and the welds were all NbC of a crystalline cubic with space group: Fm-3m (225). After the welding, the morphology of NbC changed significantly, from a polygonal shape with a diameter of 100–200 nm to a thin rod with a length of 10–50 nm. High-temperature solution-quenching treatment on single crystal rods is suggested to further improve performance.

Low‐Temperature Growth of High‐Quality Ag2HgS2 Crystals for Setup of Weak‐Light UV–Visible–NIR Photodetectors

AbstractWeak‐light photodetection shows considerable potential in both theoretical and technical aspects while it would be a key issue to explore new candidate materials for practical application in view of high reliability and durability of the devices under ambient conditions. In this work, Ag2HgS2 single crystal rods (SCRs) with length up to 1.2 cm and width ranging from 10 to 200 µm are successfully fabricated in pure phase via facile solvothermal process at 200 °C for 24 h for the first time. The Ag2HgS2 SCRs are technically investigated, and the study reveals that they are in high quality via the determination of their crystal structure, morphology, and optical properties. Density functional theory (DFT) calculations are carried out to explore more reliably details on the band structure of bulk Ag2HgS2. Meanwhile, a series of photodetectors based on the individual Ag2HgS2 SCRs are fabricated, and they convey sensitive responses to a 0.170 µW cm−2 weak light and unanimous responses to incident light with different wavelengths from 254 to 980 nm. In addition, the devices show excellent detecting performances without any obvious slump after the Ag2HgS2 SCRs exposed in air over 18 months.

Numerical study of a ring-array-concentrator for Nd:YAG solar laser pumping

In this paper, we report a numerical study of a Nd:YAG solar laser side-pumped by a ring-array concentrator (RAC) system. We used the ZEMAX© and LASCAD© software to optimize a 1.5-m diameter RAC system, a 3V-shaped pump cavity within which a Nd:YAG single-crystal laser rod (4-mm diameter, 30-mm length) is mounted, and the laser resonator parameters. The multimode solar laser output power was numerically calculated to be 34.8 W in a continuous-wave mode, corresponding to a solar laser collection efficiency of 19.69 W/m2, a slope efficiency of 3.07%, and 2.3% solar-to-laser conversion efficiency, indicating an improvement of 2.05, 1.31, and 1.5 times, respectively, relative to that of the previous results for a side-pumped Nd:YAG solar laser. Moreover, this study is the first numerical analysis of a Nd:YAG solar laser side-pumped by a RAC concentrator.

Properties of PMN-PT single crystal piezoelectric material and its application in underwater acoustic transducer

In order to further understand the characteristics of PMN-PT piezoelectric single crystal materials, the piezoelectric constant d33, impedance and frequency characteristics of PMN-PT piezoelectric single crystal elements under different pressures are studied in this paper, and the performances of PMN-PT piezoelectric single crystal elements are compared with PZT-4 piezoelectric ceramic elements. The non prestressed PMN-PT piezoelectric single crystal sandwich dipole transducer is studied and compared with PZT-4 piezoelectric ceramic sandwich dipole transducer of the same size. The matching layer broadband PMN-PT piezoelectric single crystal circular composite rod transducer is studied. The stress distribution of the transducer under 10 N pressure is calculated, and the problem of local crack of the piezoelectric single crystal element is solved from the structural design. The results show that the PMN-PT piezoelectric single crystal material has obvious advantages in low frequency performance, acoustoelectric and electroacoustic conversion efficiency, and can improve the emission and reception performance of acoustic transducer at the same time. The maximum transmitting voltage response and receiving sensitivity of the non prestressed sandwich dipole transducer can reach 144 dB and −166 dB respectively. Compared with piezoelectric ceramic transducer, the resonance frequency is reduced by about 3 kHz, and the transmitting and receiving performance are improved by 3 dB and 6 dB respectively. The matching layer broadband PMN-PT piezoelectric single crystal circular composite rod transducer has a transmitting voltage response of more than 136 dB, fluctuation of less than 5 dB, receiving sensitivity of more than −176 dB and fluctuation of less than 6 dB in the frequency range from 20 kHz to 40 kHz. The research results of this paper have important reference value and guiding significance for the popularization of PMN-PT piezoelectric single crystal material and its application in acoustic transducer.

Squared figures of merit and electromechanical coupling factors of a novel lead-free 1–3–0 composite for sensor and energy-harvesting applications

Piezoelectric sensitivity and energy-harvesting parameters are studied for a novel lead-free 1–3–0 composite where domain-engineered single-crystal rods are surrounded by a polymer matrix containing two types of air pores. Correlation between some effective parameters, concerned with the high piezoelectric sensitivity of the composite, and the elastic properties of its porous matrix is first stated. Diagrams are first built to show volume-fraction ranges wherein conditions for large squared figures of merit (Q33*)2=d33* g33*≥200⋅10−12 Pa−1 (longitudinal) and (Qh*)2=dh* gh*≥50⋅10−12 Pa−1 (hydrostatic) hold, where d33*, dh*. g33*, and gh* are piezoelectric coefficients of the composite. The studied composite is also of interest due to its large electromechanical coupling factors kt* ≈ 0.8–0.9 (thickness) and kh* ≈ 0.5–0.6 (hydrostatic). Piezoelectric sensitivity, electromechanical coupling factors and other characteristics are compared to those of a lead-containing 1–3–0 composite and a few 1–3 composites. Correlation between the effective parameters of the 1–3–0 composite and elastic properties of its porous matrix is discussed. Replacing the parallelepiped-shaped single-crystal rods with the cylindrical rods in the 1–3–0 composite leads to minor changes in the aforementioned parameters. The performance of the studied lead-free 1–3–0 composite proves its suitability for modern piezoelectric sensors, energy-harvesting and hydroacoustic devices.

Microstructural Investigations of Ni-Based Superalloys by Directional Solidification Quenching Technique.

The improvement of the mechanical properties of Ni-based superalloys is achieved in most cases by modifying the chemical composition. Besides that, the processing can be modified to optimize the as-cast microstructure with regard to the mechanical properties. In this context, the present study highlights the solidification mechanism of several Ni-based superalloys by conducting experiments using a modified, laboratory-scale Bridgman-Stockbarger furnace. In that context, the single-crystal rods are partially melted, directionally solidified and quenched sequentially. Several characterization methods are applied to further analyze the influence of the alloying elements and the variation of the withdrawal rate on the as-cast microstructure. Four stages of solidification are distinguished whereby the morphology observed in the different stages mainly depends on the cooling rate and the local concentration of the carbide forming elements. The effect of carbide precipitation and the effect on the as-cast microstructure is investigated by employing energy dispersive X-ray spectrometry (EDX) and electron backscatter diffraction (EBSD) analysis techniques. A local polycrystalline structure is observed in the single-crystal system as consequence of the influence of the carbon content and the cooling rate. The present work aims to develop strategies to suppress the formation of the polycrystalline structure to maintain the single-crystal microstructure.