Growth Of Single Crystals Research Articles

Ising-type quasi-one-dimensional ferromagnetism with anisotropic hybridization inUNi4P2

We report single-crystal growth and demonstrate Ising-type ferromagnetism with a Curie temperature of 25 K in ${\mathrm{UNi}}_{4}{\mathrm{P}}_{2}$ by means of magnetization, electrical transport, and specific heat measurements. Uniaxial anisotropy in magnetism and $cf$ hybridization are well reflected not only in the crystallographic $ac$ plane but also within the basal plane of the tetragonal unit cell owing to the quasi-one-dimensional crystal and electronic structure of ${\mathrm{UNi}}_{4}{\mathrm{P}}_{2}$. The strong anisotropy between the $c$ axis and the tetragonal basal plane is retained up to 57 T, while the intraplane anisotropy in the basal plane gradually vanishes at higher fields. Our results show that anisotropic electron correlations may stabilize the elusive Ising-type ferromagnetic order in one dimension at nonzero temperatures, presumably with its own characteristic universality class.

Bridgman Growth of Mg2Sn1–xBixSingle Crystals and Anisotropic Thermoelectric Properties

Mg2X-based (X = Si, Ge, Sn) phases are promising for thermoelectric applications due to their nontoxicity, low cost, and high performance. Substantial experimental work has already been carried out based on the polycrystalline samples; however, studies on related single-crystal growth and corresponding properties are still very limited owing to the high volatility and reactivity of Mg, which makes it very challenging to obtain high-quality single crystals with big sizes. In this report, for the first time, the Bridgman method was successfully applied in the single-crystal growth of the Bi-doped Mg2Sn materials. The crystals are of high quality and related anisotropic thermoelectric properties were systematically investigated. The Bi-doped Mg2Sn0.99Bi0.01 single crystal exhibited a maximum zT value of 0.58 along the [111] orientation at 623 K, which is about 30 times that of the pristine Mg2Sn single crystal.

Crystal growth, structural and DFT study of novel single crystal (E)-N’-(2-chlorobenzylidene)-4-fluorobenzohydrazide for nonlinear optical applications

Nonlinear optical (NLO) material, (E)-N'-(2-chlorobenzylidene)-4-fluorobenzohydrazide (CBBH) novel single crystal was grown via a Schiff base chemical reaction. A single crystal X-ray diffraction technique was utilized for the recognition of the crystal structure of the CBBH. The imperfection of novel CBBH crystal was checked by high resolution X-ray diffraction (HRXRD) study. Hirshfeld surface study through colour coding was applied to know the intra and intermolecular force interactions. Fourier transforms infrared (FTIR), proton 1H and carbon 13C nuclear magnetic resonance (NMR) spectra were employed to elucidate the various functional groups and structure of the crystal. The absorption maxima from UV–Vis plot for the CBBH molecule was found at 314 nm, which reveals the π-π* transition. Photololuminescence (PL) study reveals that emission observed in the blue-violet region. The HOMO and LUMO energies were investigated using the density functional theory (DFT) method. Natural bond orbital (NBO) analysis explored the donor-acceptor exchanges and it's endurance into intra-molecularly. The first-order hyperpolarizability value, β0 = 23.73 × 1030 esu was observed for CBBH crystal, which is ∼64 times larger than that of urea molecule (0.3728 × 1030 esu). Z-scan experiment on CBBH crystal supports its third-order nonlinear optical (NLO) properties. Optical limiting analysis indicates reverse saturation absorption behavior of CBBH crystal.

Growth, structural, optical, and thermal behavior of bibenzyl organic single crystal for scintillator applications

Growth, structural, optical, and thermal behavior of bibenzyl organic single crystal for scintillator applications

Investigation on the crystal growth, optical, mechanical, and third harmonic generation properties of 2-aminopyridinium adipate monoadipic acid dihydrate single crystal

Investigation on the crystal growth, optical, mechanical, and third harmonic generation properties of 2-aminopyridinium adipate monoadipic acid dihydrate single crystal

Growth and spectroscopic properties investigation of Er-doped BGSO single crystal: A potential gain medium for eye-safe laser

Erbium-doped crystals are well-suited for eye-safe solid-state laser systems around 1.5 μm. Broadband and high-gain Er-doped laser crystals can achieve high-power tunable laser output, which plays a great role in promoting commercial eye-safe laser research. Herein, the 2 at% Er-doped bismuth germanium silicate (BGSO) laser crystal is successfully grown by the vertical Bridgman method. The X-ray Rietveld refinement was used to obtain the structural parameters. The spectroscopic parameters of Er ions in BGSO crystal are calculated and analyzed with Judd-Ofelt theory. Furthermore, the broadband luminescence is observed in the wavelength range of 1450–1600 nm. The stimulated emission cross-section is calculated around 1500 nm, which largest value is 5.31 × 10−20 cm2 at 1543 nm. Meanwhile, the luminous efficiency of BGSO crystal in the eye-safe band is further characterized and explored by studying the energy transfer process and anomalous thermal quenching in the 550 nm and 660 nm bands. All results indicate that the Er: BGSO crystal is a promising broadband eye-safe laser material.

A novel two-step route to unidirectional growth of multilayer MoS2 nanoribbons

Alkali-assisted chemical vapour deposition (CVD) of transition metal dichalcogenides (TMDs) has been shown to promote the growth of large single crystals of TMD monolayers. The morphology control of TMDs is a key parameter for the scalable synthesis of versatile layered materials. This work demonstrates that the alkali-assisted synthesis provides a route toward fabricating highly crystalline MoS2 nanoribbons. Our proposed method involves a vapour-liquid–solid phase reaction between MoOx(2 < x < 3) precursors grown by Pulsed Laser Deposition (PLD) and metal alkali halide (i.e., NaF). The growth process evolves via the emergence of the Na–Mo–O liquid phase, which mediates the formation of MoS2 multilayer nanoribbons in a sulfur-rich environment. Moreover, the as-grown MoS2 nanoribbons are surrounded by mono- and multilayer triangles of MoS2 and exhibit a preferential alignment defined by both MoS2 crystal symmetry and the underlying Al2O3 substrate. In addition, we observe a significant built-in strain in the as-grown MoS2 nanostructures, which increase in magnitude from the multilayer nanoribbons to the triangular monolayers, and which can be effectively released upon transfer onto another substrate. The growth method developed here can enable flexibility in designing nanoelectronic devices based on TMDs with tunable dimensions.

Significant magneto-dielectric effect in SrNd2Fe2O7 at room temperature

Here, we report the growth of (Sr, Ca) Nd2Fe2O7 single crystals with the Ruddlesden–Popper structure using an optical floating-zone method. A significantly anisotropic magneto-dielectric effect (MD), ab-plane and c-axial MD coefficients reaching −12.3% and −8.4% measured at 103 Hz in a 1 T magnetic field, can be obtained in a SrNd2Fe2O7 crystal at room temperature. The corresponding anisotropic MD ratio can be reached as high as 1.46. With an increase in the Ca concentration, the MD effect decreases dramatically and is eventually completely suppressed in both directions. Analysis of magnetic properties and 57Fe Mössbauer spectra suggests that the anisotropic MD effects in SrNd2Fe2O7 can be attributed to polaronic hopping between two neighboring Fe3+ ions through oxygen vacancies in an anisotropically antiferromagnetic matrix; the disappearance of the MD effect in Ca-doped SrNd2Fe2O7 is a consequence of the suppression of the antiferromagnetism. Our work suggests that the significantly anisotropic MD effect in SrNd2Fe2O7 crystals at room temperature can be used in magneto-dielectric controlled devices.

On Comparing Crystal Growth Rates: Para Substituted Carboxylic Acids

In this contribution the single crystal growth rates of four para substituted benzoic acids measured in toluene and isopropyl alcohol solutions are reported. Major objectives of the work have been to consider how such data might be correctly compared and how such comparisons may be related to underlying packing arrangements in the respective crystal structures. Morphological determinations formed an important part of the overall study. Consideration has been given to various practical issues arising from the varying solubility of the materials and growth rate dispersion among the measured crystal seeds. This provides suggestions as how best to measure growth rates for this purpose. The ultimate aims of such work have been to explore connections between growth and nucleation kinetics as well as to consider what such a data set might predict about the kinetics of other related molecules.

Synthesis, crystal growth, structural and physicochemical properties of N-methylurea benzoic acid single crystal for non-linear optical applications

The organic single crystal of N-methylurea benzoic acid (NMUB) was synthesized and successfully grown from a slow evaporation solution growth technique for the first time in literature. The structure of the NMUB single crystal was analyzed by Single crystal X-ray diffraction (SCXRD); the crystallization of the NMUB crystal was a monoclinic crystal system with the space group P21/c. The crystal structure was combined by the carboxylic groups of H- atoms in benzoic acid with protonated N-methylurea anions. The FTIR and 1H, 13C NMR chemical shifts were analyzed by distinct vibrational groups and molecular structures. The PXRD ascertains the grown crystal crystallographic planes and crystalline nature. The Hirshfeld surfaces analysis determines the theoretical inter and intra-molecular interaction with the aid of color coding. The UV-Vis NIR spectra revealed the low absorption edge, and the optical band gap was anticipated. The crystal thermal and mechanical stability was analyzed by TG/DTA, Vickers microhardness, and void volume. The laser utility limitation for the crystal was determined through laser beam irradiated LDT analysis. The third-order optical non-linear parameters were determined from the z-scan technique.

High-yield growth of FACsPbBr3 single crystals with low defect density from mixed solvents for gamma-ray spectroscopy

High-yield growth of FACsPbBr3 single crystals with low defect density from mixed solvents for gamma-ray spectroscopy

Structural and Improper Ferroelectric Properties of TbInO3 Single Crystal Grown by Laser Floating Zone

The honeycomb TbInO3 has attracted wide research attention due to its fascinating physical properties. However, TbInO3 single crystal was difficult to grow owing to the high melting point and serious volatilization of indium during the crystal growth. In this study, the volatilization of the indium element was effectively suppressed by controlling the growth atmosphere and pressure. The excess ratio of indium oxide was determined, and pure hexagonal TbInO3 crystal was obtained by the laser floating zone method. Systematic studies on the crystal structure and optical and ferroelectric properties were carried out. The structure distortion resulted in the improper geometric ferroelectric revealed by single crystal diffraction and Raman spectrum measurements. The topological vortex domains and P-E hysteresis loop demonstrated the presence of ferroelectricity. TbInO3 crystal has great potential application in vortex memory.

Universal epitaxy of non-centrosymmetric two-dimensional single-crystal metal dichalcogenides

The great challenge for the growth of non-centrosymmetric 2D single crystals is to break the equivalence of antiparallel grains. Even though this pursuit has been partially achieved in boron nitride and transition metal dichalcogenides (TMDs) growth, the key factors that determine the epitaxy of non-centrosymmetric 2D single crystals are still unclear. Here we report a universal methodology for the epitaxy of non-centrosymmetric 2D metal dichalcogenides enabled by accurate time sequence control of the simultaneous formation of grain nuclei and substrate steps. With this methodology, we have demonstrated the epitaxy of unidirectionally aligned MoS2 grains on a, c, m, n, r and v plane Al2O3 as well as MgO and TiO2 substrates. This approach is also applicable to many TMDs, such as WS2, NbS2, MoSe2, WSe2 and NbSe2. This study reveals a robust mechanism for the growth of various 2D single crystals and thus paves the way for their potential applications.

Impact of Marangoni effect of oxygen on solid–liquid interface shape during Czochralski silicon growth applied with transverse magnetic field

This study investigated the impact of the Marangoni effect of oxygen on the solid–liquid interface shape in the silicon single-crystal growth process by the transverse magnetic-field-applied Czochralski (Cz) method. To this end, the results of a 3D heat and mass transfer analysis were compared with the experimental results. The findings of the study revealed that the Marangoni effect of oxygen affected the solid–liquid interface shape predicted by the simulation. Moreover, with the introduction of this effect, both the solid–liquid interface shape and temperature distribution of the melt were found to be in good agreement with the experimental values.

Growth and characterization of sodium potassium niobate single crystals near morphotropic phase boundaries

By using a high-temperature solution approach, lead-free single crystals of sodium potassium niobate Kx Na(1-x)NbO3 have been grown at three different phase boundary compositions (x = 0.17, 0.35, and 0.50). The monoclinic and orthorhombic crystal structures are present in the compositions × = 0.17 and × = 0.50 related crystal structures. Ferroelectricity is induced at lower temperatures and requires a smaller critical electric field when KNbO3 content is included into NaNbO3 crystals. Studies using the scanning electron microscope (SEM) and atomic force microscope (AFM) have shown how the sodium potassium niobate (KNN) crystals grow morphologically. With an increase in potassium concentration in the KNN system, the average step size falls. KNN crystals were subjected to impedance analyzer-based dielectric investigations. With an increase in concentration, a decrease in dielectric loss was found. The compositions with potassium concentrations of x = 0.50, 0.35, and 0.17 were found to have piezoelectric coefficients (d33) of 72 pC/N, 63 pC/N, and 52 pC/N, respectively.

Additive-Enhanced Crystallization of Inorganic Perovskite Single Crystals for High-Sensitivity X-Ray Detection.

Inorganic cesium lead halide perovskite single crystals are particularly intriguing to ionizing radiation detection by virtue of their material stability and high attenuation coefficients. However, the growth of high-quality inorganic perovskite single crystals remains challenging, mainly due to the limited solubility. In this work, an additive-enhanced crystallization method is proposed for cesium lead perovskites. The additive can remarkably increase the solubility of cesium bromide in dimethyl sulfoxide (DMSO) forming a balanced stoichiometric precursor solution, which prevents the formation of impurity phases. In addition, the additives would react with DMSO generating glyoxylic acid (GLA) via nucleophilic substitution and Kornblum oxidation reactions. The GLA can form stable PbBr2 -DMSO-GLA complexes, which enables better crystallinity, uniformity and much longer carrier lifetimes for the grown single crystals. The X-ray detectors using the additive-enhanced crystals exhibit an ultra-high sensitivity of 3.0 × 104 µC Gyair -1 cm-2 which is more than two orders of magnitude higher than that for the control devices.

Mesoscale simulations of spherulite growth during isothermal crystallization of polymer melts via an enhanced 3D phase-field model

A finite difference-based 3D phase-field model is developed to investigate the spherulite growth at the mesoscopic scale during the isothermal crystallization of polyamide (PA) 12. The model introduces a phase-field variable to distinguish the crystalline and amorphous phases of polymers. The phase-field evolution equation is coupled with the heat conduction equation that considers the latent heat of crystallization. The evolution equations introduce both the dimensionless diffusivity and latent heat that are dependent on the crystallization temperature. A high-order finite difference-based numerical framework is applied to the phase-field model. Both the qualitative simulation results of the phase-field model such as the crystal morphologies and the quantitative results including the radial crystal growth rate, degree of crystallinity, and lamellar thickness are validated against experiments. The simulation for single-crystal growth shows that a high crystallization temperature results in a large crystal with a slow radial growth rate. The simulation for multi-crystal growth shows that the crystals impinge on each other and finally fill the whole domain during crystallization, which further demonstrates the capability of the model in simulating the spherulite growth during isothermal crystallization of polymer melts.

Porous Single Crystals at the Macroscale: From Growth to Application.

ConspectusPorous materials have wide applications in the fields of catalysis, separation, and energy conversion and storage. Porous materials contain pores that are specifically designed to achieve expectant performance. The solid phases in porous materials are normally completely continuous to form the basic porous frame while the pores are fluid phase within the solid phase. Single crystals are macroscopic materials in three spatial dimensions with the constituent atoms, ions, molecules, or molecular assemblies arranged in an orderly repeating pattern with the ordered structures. The growth of single crystals is indeed a process to arrange these constituents in three dimensions into a repeating pattern within the materials. Today the applications of single crystals are exponentially growing in wide fields, and single crystals are therefore unacknowledged as the pillars of our modern technology. Introducing porosity into single crystals would be expected to create a new kind of porous material in which the basic porous frames are single-crystalline and free of grain boundaries. The structural symmetry is completely maintained within the basic porous frames which are a continuous solid phase, but it is completely lost inside the pores. The porous architecture is free of grain boundaries, and the fully interconnected skeletons are in single-crystalline states within the basic porous frames. Single crystals with porosities can therefore be considered to be a new kind of porous material, but they are single-crystal-like because the structural symmetry is maintained only in the skeletons and completely lost within the pores. We therefore call them porous single crystals or consider them in porous single-crystalline states to stand out with their structural features. Porous single crystals at the macroscale combine the advantages of porous materials and single crystals to incorporate both porosity and structural coherence in a porous architecture, leading to invaluable opportunities to alter the material's properties by controlling the unique structural features to enhance its performance. However, the growth of single crystals in three dimensions reduces the formation of porosities, leading to a fundamental challenge for introducing porosity into single crystals in a traditional process of crystal growth. In this Account, we report the rational design, growth methodology, and microstructural engineering of porous single crystals in a solid-solid transformation. We rationally design a high-density mother phase in a single-crystalline state and transform it into a low-density new phase in a single-crystalline state to introduce porosities into single crystals even incorporating the removal of specific compositions from the mother phase during the growth of porous single crystals. The porosity can be tailored by controlling the change in relative densities from the mother phase to the porous single crystals while the pore size can be engineered by controlling the fabrication conditions. Considering the unique structural features, we explore their functionalities and applications in photoelectrochemical energy conversion, electrochemical alkane conversion, and electrochemical energy storage. We believe that the materials, if tailored into porous single-crystalline states, would not only find a broad range of applications in other fields but also enable a new path for material innovations.

Effects of crystal rotation on the carbon transport in the top-seeded solution growth of SiC single crystal

To achieve a high and uniform growth rate for the solution growth of silicon carbide (SiC), the fluid flow and carbon transport in the solution should be well estimated and controlled. The application of crystal rotation is effective in controlling the flow pattern and carbon transport in the SiC growth system. In this paper, the effects of crystal rotation on the solution flow, carbon concentration and growth rate for growing SiC crystals were numerically investigated by using a global heat and mass transfer model. The results indicated that crystal rotation strongly enhances the convection in the solution and makes the upward flow proceed deeper, resulting in the distribution of radial temperature along the growth interface turning from convex to concave towards the solution with the increase in the crystal rotation rate. Consequently, the carbon transport in the solution is strengthened, leading to an increase in the maximum value of the growth rate with a higher crystal rotation rate. However, the radial uniformity of the crystal growth rate along the growth interface becomes poor due to the hot solution moving upward to the center of the seed crystal with the increase in the crystal rotation rate. In the present study, it is found that the intensity of the forced convection vortex generated by an intermediate crystal rotation rate is beneficial to obtain a uniform distribution of growth rate and a relatively high growth rate.

Technology for the Nondestructive Reprocessing of Sodium Iodide Technogenic Solutions into a Charge for Single Crystal Growth

Introduction. The production of NaI-based single crystals results in accumulation of great amount of liquid waste. To bring valuable constituents of this waste back, the NaI technogenic solutions are treated to precipitate iodine that is further used in the synthesis of high-pure NaI. However, the least contaminated part of the waste may be brought back into the main technological process without the intermediary stage of iodine destruction, which allows a considerable cost saving.Problem Statement. There have been no data on the effective purification coefficients for NaI solutions subsequently treated with barium hydroxide, sodium carbonate, and by mass crystallization. Requirements to impurity content, which NaI solutions have to comply with in order to be used in the nondestructive treatment have mot been not formulated.Purpose. The purpose of this research is to develop a technology for reprocessing NaI technogenic solutionsinto sodium iodide of high purity without NaI destruction at the intermediate stage.Material and Methods. The materials that have been used for this research are as follows: aqueous solutions of NaI-based crystal production waste, active coal, barium hydroxide, sodium carbonate. The methods that have been employed are the treatment of NaI solutions with barium hydroxide, sodium carbonate, and by mass crystallization. Results. The technology of NaI solution purification by treatment with barium hydroxide and sodium carbonate with further mass crystallization of the purified salt has been developed. This technology is more environment friendly and cheaper than the conventional one that includes obtaining pure iodine. A series of NaI technogenic solutions has been treated in laboratory conditions and on industrial equipment, and the efficiency of their purification by the chemical treatment and mass crystallization hasbeen estimated. The impurity content in the obtained salt and the scintillation parameters of grown NaI : Tl crystals meet the requirements for these products.Conclusions. The technology has been implemented in the manufacturing process at the pilot plant of the Institute for Scintillation Materials of the NAS of Ukraine. It may be used at other enterprises that deal with alkali metal iodide waste treatment.