Nature and spatial distribution of extended defects in Czochralski-grown Ca3RE2(BO3)4 (RE = Y, Gd) orthoborate single crystals

Pure and Nd-doped Ca3Y2(BO3)4 and Ca3Gd2(BO3)4 orthoborate (space group Pnma) single crystals are considered for applications as materials for optoelectronics, in particular for ultrafast pulse lasers. In the present work, Czochralski-grown single crystals of such materials were studied. All of them were nearly free of defects such as impurity phases or gas bubble inclusions, previously observed and reported in similar orthoborates. Laboratory high-resolution x-ray diffraction together with synchrotron radiation-based white-beam x-ray topography have been employed as experimental techniques. In this paper we perform for the first time a systematic study of extended defects present in those crystals, including the spatial distribution of the defects. The crystal quality of the studied Ca3RE2(BO3)4 samples is relatively good—the mean values of double-axis rocking-curve full width at half maximum are low enough low (in the order of 32–131 arcsec) and comparable with literature results obtained for other borate crystals. The chemical composition is generally uniform along the samples. The nature of the extended defects is recognized—they are mainly crystal blocks with low misorientation angles  ≤0.06°), micromosaics, dislocations, and crystallographic plane bending. A detailed analysis of the bend for each crystal is presented. Simple criteria for classifying bulk crystals in terms of bending profile are formulated.

Source:IOPscience

For more information, please visit our website: https://www.powerwaywafer.com,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Stress-induced martensitic transformation in high-strength [236]-oriented Ni51Ti36.5Hf12.5 single crystals

The effects of heat treatment on the stress-induced B2-B19' martensitic transformations in the Ni51.0Ti36.5Hf12.5 single crystals oriented along [236] direction are studied. It is shown that in the annealed at 1323K for 4 h crystals, the temperature range of superelasticity increase almost twofold from 75K up to 135K as compared to the as-grown single crystal contained disperse particles of H-phase. The [236]-oriented Ni51.0Ti36.5Hf12.5 single crystals are characterized with high levels of applied compressive stress up to 1700 MPa in the as-grown state and 1900 MPa in annealed crystals for the completely reversible stress- induced B2-B19' martensitic transformation with reversible strain up to |εSE| =1.4%.

Source:IOPscience

For more information, please visit our website: https://www.powerwaywafer.com,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Growth of large sized Y Ba2Cu3O7 single crystals using the top seeded melt growth process

Neutron scattering experiments are fundamental to the study of magnetic order and related phenomena in a range of superconducting and magnetic materials. Traditional methods of crystal growth, however, do not yield single crystals of sufficient size for practical neutron scattering measurements. In this paper, we demonstrate the growth of relatively pure, large Y Ba2Cu3O7 single crystals up to 30 mm in diameter using a top seeded melt growth process. The characterization of the microstructural and magnetic properties of these crystals indicates that they contain <2% of impurity phases and, hence, exhibit only weak flux pinning behaviour.

Source:IOPscience

For more information, please visit our website: https://www.powerwaywafer.com,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

FeTe0.6Se0.4 bulk single crystals with high critical current densities under magnetic fields

We have fabricated FeTe0.6Se0.4 large-size bulk single crystals with high critical current densities (J c) under magnetic fields. FeTe0.6Se0.4 single crystals were prepared by the melting method with two stage heat treatments. The X-ray diffraction (XRD) analysis and the remanent magnetization method showed that the fabricated bulk crystals are intrinsically single crystals from viewpoint of the critical current flow. Temperature dependence of magnetization revealed that low-T c region exists inside the crystals. The magnetization curves indicated the typical fishtail type, and the magnetic Jc under the magnetic field parallel to the c-axis at 4.2 K achieved 0.36 and 0.2 MA / cm2 at 0 T and 5 T respectively. From the temperature scaling behavior of flux pinning properties we speculated that low-T c regions near excess Fe moderately distributed inside the crystals are dominant pinning centers in high fields at low temperatures.

Source:IOPscience

For more information, please visit our website: https://www.powerwaywafer.com,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Host and defect-related luminescence in Rb2KTiOF5 oxyfluoride crystals irradiated by fast electrons

The paper presents a comparative analysis of RKTF crystals (full name single crystals Rb2KTiOF5), and RKTF + e crystals, single crystals irradiated on a cyclotron by fast electrons Rb2KTiOF5. The crystals were grown by slow solidification method. The study was conducted at a temperature from 7 to 400 K for various types of optical and radiation effects. Spectra of photoluminescence (PL) and X-ray excited luminescence (XRL) in region of 1.5-5.5 eV, time-resolved pulse cathode-luminescence (PCL) spectra, the temperature depending of the XRL, luminescence decay kinetics were studied. Single crystal RKTF are transparent from microwave up to the edge of the long-wave fundamental absorption (near UV range). We detected three luminescence bands for RKTF, in the visible spectral region, that were attributed to radiative annihilation of intrinsic excitons (2.25 eV), recombinaion-type luminescence (2.1 eV) and luminescence of higher TiOF5 complexes (1.9 eV), for all emission bands characterized by great (~1.5-1.8 eV) Stokes shift. The exponential component with lifetime of approximately 19 μs was found in the PCL decay kinetics at 2.25 eV. In the crystal RKTF + e we detected new luminescence bands 2.6 eV and 3.2 eV and the disappearance of the RKTF luminescence bands. Stokes shift of the band 3.2 eV of the RKTF + e crystal is much smaller and is equal to 0.7 eV. Excitation of the band 3.2 eV occurs in the field of crystal transparency, which indicates the defective nature of the glow. PCL decay kinetics at 2.0 and 2.5 eV has a complex nature and consists of at least two components with a life time of 0.5 ms and 6 ms, that significantly more in comparison with RKTF. Irradiation by fast electrons of crystals Rb2KTiOF5 led to entirely new optical properties and suppression of self-luminescence of the crystals.

Source:IOPscience

For more information, please visit our website: https://www.powerwaywafer.com,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

In-plane doping profile control of plate-like organic single crystals grown by a method combining electrospray and low vapor pressure liquid film

Although the molecular doping of single crystal organic semiconductors is expected as a key technology that imparts attractive functions in optical and electrical properties, the doping technology in single crystal organic material is still in the initial stages. In this study, doping profile control in the organic single crystal was examined by using an organic single crystal growth method in which a low vapor pressure liquid thin film is used as a crystal growth field and solutes are supplied by electrospray deposition. Steep doping profile control with a transition region of around 1–2 μm was demonstrated using dopants of small molecule red dye and green fluorescent polymer into plate-like single crystal of widegap fluorescent small molecule. We also evaluated the doping profile of the small molecule red dye in microwire-like single crystals of green fluorescent metal complex small molecule.

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net

send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

The Corrosion of Single Crystals and Recrystallized Single Crystals of Iron and Steel in Citric Acid

Corrosion studies, largely in 0.2M citric acid at 20°C and the boiling point, were made on polycrystalline disks and monocrystalline spheres and disks of Armco iron and type L steel. Preliminary experiments indicated that the (100) face corroded at the slowest rate and the minor faces, of which the (321) is an example, corroded at the most rapid rate. Quantitative measurements were confined to these two crystal faces. The (100) face was cathodic to the (321) face as shown by potential measurements in 0.2M citric acid in the presence and absence of air. The rate of corrosion of the (321) face was approximately twice that of the (100) face on specimens which were chemically polished, electrolytically polished, machined with a sharp lathe tool, or polished with emery paper. The rates of corrosion of the polycrystalline starting material from which the single crystals were prepared were several times greater than those of the single crystals. Conversion of the single crystals to polycrystalline material by heating through the transformation temperature resulted in a considerably increased corrosion rate. In the presence of 40–45 ppm of Sn(II) the rates of corrosion of the single crystals in 0.2M citric acid at the boiling point were reduced greatly and no significant difference between the (100) and (321) faces was observed.

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

The Atmospheric Sulfidation of Copper Single Crystals

The oxidation of copper single crystals is known to proceed at different rates on different crystal faces. To determine whether this behavior extends to subsequent atmospheric sulfidation as well, we have exposed polycrystalline copper and (100), (110), and (111) single crystals of copper to low concentrations of hydrogen sulfide in high humidity air. For short exposures, all of the single crystals sulfidize much more slowly than does polycrystalline copper. In each case,  is the predominant sulfur species formed. As with oxide formation on copper single crystals, there is a slight tendency for the (111) face to be the most inert. For long exposures, the sulfide film on the single‐crystal samples increases to become essentially equal to that on polycrystalline copper. We envision a corrosion process initially controlled by grain boundary diffusion (and thus the degree of crystallinity of the underlying oxide), followed by a transition to a regime in which the diffusion of copper ions through  limits the growth of the corrosion film.

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Pyroelectric properties and electrocaloric effect in TGS1−xPx single crystals

Triglycine sulfate (TGS) single crystals modified with phosphoric acid (TGS1−xPx) have been grown by slow evaporation technique at room temperature. Lattice parameters were identified by using single crystal x-ray diffractometer. The dielectric, pyroelectric, ferroelectric properties and electrocaloric effect have been investigated. Curie temperature of grown crystals was determined from dielectric constant measurements at various temperatures at a frequency of 1 kHz. The Curie temperature is found decreased for the TGS single crystals with the addition of phosphoric acid. Room temperature P-E hysteresis loops of TGS1−xPx single crystals are presented. The values of coercive field Ec, spontaneous polarization Ps and internal bias field Eb were obtained from the hysteresis loops. Discussion on pyroelectric properties as a function of temperature and applied electric field is presented. Figure of merits (FOMs) were determined to study the pyroelectric performance of the grown crystals. Among all compositions of x, x = 0.2 (i.e., TGS0.8P0.2) single crystals exhibited the largest pyroelectric coefficient and pyroelectric figure of merit at room temperature. From the above investigations the electrocaloric temperature change, ΔT of TGS1−xPxsingle crystals at selected applied fields and temperatures are obtained by indirect method and discussed.

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,

send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Synthesis of Single Crystal LiNi0.88Co0.09Al0.03O2 with a Two-Step Lithiation Method

Single crystal positive electrode materials for lithium-ion batteries have superior properties compared to their polycrystalline counterparts as has been demonstrated by industry and academia. Single crystal LiNi0.5Mn0.3Co0.2O2 (NMC532), NMC622 and now NMC811 have been successfully commercialized. However, single crystal LiNi1-x-yCoxAlyO2(NCA) materials have not been reported yet. One simple method for producing single crystal NMC material requiring high temperature and excess lithium during synthesis creates Li5AlO4 impurities if applied directly in attempts to synthesize single crystal NCA materials. This work introduces a two-step lithiation method for single crystal LiNi0.88Co0.09Al0.03O2 synthesis, which can prevent the formation of Li5AlO4 impurities. Powder X-ray diffraction, electron backscatter diffraction, and electrochemical measurements show the viability of the two-step lithiation method. Full coin cell cycling shows that the capacity retention of the single crystal NCA samples is at least as good as their polycrystalline counterparts. It is believed that this two-step lithiation method can be used for the synthesis of single crystal NCA and other single crystal Al-containing positive electrode materials. We believe this can lead to longer lived Li-ion cells with Ni-rich positive electrode materials.

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,

send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Continuous depth-of-interaction measurement in a single-layer pixelated crystal array using a single-ended readout

We propose a depth-of-interaction (DOI)-encoding method to extract continuous DOI information using a single-layer scintillation crystal array with single-ended readout for cost-effective high-resolution positron emission tomography (PET). DOI information is estimated by different light dispersions along the x- and y-directions tailored by the geometric shape of reflectors around the crystals. The detector module comprised a 22 × 22 array of unpolished LGSO crystals (2.0 × 2.0 × 20 mm3). A multi-anode photomultiplier tube with 64 anodes measured light dispersion in the crystal array. Gain non-uniformity of each anode was corrected by an analogue gain compensation circuit. DOI information was determined from peaks in the x and y anode-signal distributions normalized by the total energy of the distribution. Average DOI resolution (full width at half maximum, FWHM) over all crystals and depths was estimated to be 4.2 mm. Average energy resolution from the 2 to 18 mm DOI positions was 11.3% ± 0.79%, with 13% difference in photo-peak positions. Average time resolutions (FWHM) were 320–356 ps. Energy, time and DOI resolutions were uniform over all crystal positions except at the array's edge. This DOI-PET detector shows promise for applications that require high resolution and sensitivity at low cost.

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Prediction of four, six or eight ears in drawn cups of single-crystal aluminum sheets

The new single crystal criterion developed by Cazacu, Revil and Chandola (2017) was implemented in a finite-element (FE) code and applied to forming of single-crystal cups of aluminum. Drawing simulations were conducted for circular single-crystal blanks of three different orientations: {100}〈001〉, {111} and [112] using the same set of parameters for the single-crystal yield criterion. A strong influence of anisotropy (single-crystal orientation) on the earing profile is found. While for the {100}〈001〉 orientation it is predicted that four ears develop, for the {111} and [112] crystal orientations six and eight ears are predicted, respectively. The FE simulation results are consistent with experimental observations of Tucker (1961).

Source:IOPscience

For more information, please visit our website: www.semiconductorwafers.net,

send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Organic single-crystal TFT

Rubrene single-crystal TFT (thin-film transistor) made on a kapton substrate using rubrene single crystal grown by physical vapor transport remains unaffected by bending up to a radius of 9.4 mm. BPEA {9,10-bis(phenylethynyl) anthracene} single crystal TFT fabricated on polyimide film shows good endurance to bending. The difficulty of precise placement of crystals at defined locations is avoided by making OTS (octadecyltriethoxysilane) domains on source/drain electrode pattern using an OTS-inked stamp, from where the organic crystals can be selectively grown. CuPc {copper(II) phthalocyanine} and F16CuPc (copper hexadecafluorophthalocyanine) single crystal TFTs are transferred to a gold wire to make a complementary inverter circuit.

Source:IOPscience

For more information, please visit our website:  www.semiconductorwafers.net,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com

Optical non-linearities by Z-scan measurements, thermal characterization of single crystal: 8-hydroxyquinolinium 3-carboxy-4-hydroxy benzene sulfonate monohydrate

Single crystals of 8-hydroxyquinolinium 3-carboxy-4-hydroxy benzene sulfonate monohydrate were grown by slow evaporation technique at room temperature by using ethanol as solvent. Single crystal X-ray diffraction study elucidated that the crystal structure of8-hydroxyquinolinium 3-carboxy-4-hydroxy benzene sulfonate monohydrate belongs to monoclinic crystal system with space group P21/n. The solid state physical parameters have been also determined for the grown crystal from the single crystal data. The cut-off wavelength and optical band gap energy of grown crystal was found to be 420 nm and 2.67 eV respectively.Thermogravimetric and differential thermal analysis reveals that the 8-hydroxyquinolinium 3-carboxy-4-hydroxy benzene sulfonate monohydrate single crystal is thermally stable up to 144˚C without any weight loss. The mechanical properties of the grown crystal were studied by Vickers microhardness technique and it is found that 8-hydroxyquinolinium 3-carboxy-4-hydroxybenzene sulfonate monohydrate belongs to hard material category. The third order nonlinear refractive index (n2), nonlinear absorption coefficient (β) and non

Source:IOPscience

For more information, please visit our website:  www.semiconductorwafers.net,
send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com