Growth Of Single Crystals Research Articles

Niobium monoxide NbO single crystal growing by floating zone method

In this work, a single crystal of niobium monoxide NbO was grown by crucible-free zone melting method. Polycrystalline NbO with ordered cubic structure (sp.gr. Pm-3m) with vacancies in both metal and nonmetal sublattices served as an initial material. According to XRD data, the grown niobium monoxide NbO single crystal has predominant growth in the [111]B1 direction and contains only one ordered cubic phase NbO, its lattice constant is equal to a = 421.2 pm. The growing mechanism of the NbO single crystal was clarified, in accordance with the Kossel and Stransky theory, it was suggested that the single crystal grows layer by layer. Analysis of the Kikuchi lines geometry allowed the orientations and disorientations of single crystal to be determined to high precision. An analysis of the diffraction pattern and intersection of Kikuchi lines showed that the NbO single crystal has (111)B1 facet. The experimental Laue diffraction patterns confirmed this direction of niobium monoxide NbO single crystal growth.

Growth of TiO2 single crystals by the Verneuil method at different gas flow ratio

The oxygen-rich atmosphere is a prerequisite for the preparation of high-quality TiO2 single crystals using the Verneuil method. However, too much oxygen will bring down the temperature of the growing chamber, so the key to growing high-quality TiO2 single crystals is to ensure that the temperature distribution is stable and that the heat in the growth chamber is in equilibrium. In this paper, TiO2 single crystals were prepared by the Verneuil method under different gas flow ratio. Due to the inability to obtain a stable temperature field, the crystals produced at the hydrogen-to-oxygen ratios of 1.4 and 1.8 both had substantial dislocation densities and low optical transmittance. The heat in the growth chamber reaches equilibrium and the temperature distribution is steady-state when the hydrogen-to-oxygen ratio is 1.6. The FWHM of the crystal obtained under this condition is 0.02334°, the transmittance is nearly 70 %, and the etch pit density is only 6.21 × 104 cm−2. This work is a major boost to the industrial production of rutile crystals.

Preparation and magnetic properties of magnetically anisotropic 2:17-type SmCo alloy spherical particles

This study utilized the irregular Sm(Co0.69Fe0.22Cu0.07Zr0.02)8.1 alloy powder as the primary material, combining the solid/liquid interface de-wetting effect and abnormal grain growth method for preparing the 1:7-type SmCo spherical single crystal powder. Through aging heat treatment, the anisotropic 2:17-type SmCo alloy spherical permanent magnetic powder with size distribution of 30–130 μm was successfully obtained. The study explored the spheroidization mechanism and single crystal growth rule of Sm(Co0.69Fe0.22Cu0.07Zr0.02)8.1 alloy powder, as well as the impact of solution-aging magnetic hardening treatment on the permanent magnet properties. The optimized permanent magnetic properties of the resulting 2:17-type SmCo alloy spherical powder were coercivity Hic = 1244 kA/m, and maximum magnetic energy product (BH)max = 224.5 kJ/m3 at room temperature. The anisotropic 2:17-type SmCo alloy spherical magnetic powder prepared using this method exhibits significant potential applications in the production of bonded magnets.

Growth of millimeter-sized high-quality CuFeSe2 single crystals by the molten salt method and study of their semiconducting behavior

An eutectic AlCl3/KCl molten salt method in a horizontal configuration was employed to grow millimeter-sized and composition homogeneous CuFeSe2 single crystals due to the continuous growth process in a temperature gradient induced solution convection. The typical as-grown CuFeSe2 single crystals in cubic forms are nearly 1.6 × 1.2 × 1.0 mm3 in size. The chemical composition and homogeneity of the crystals was examined by both inductively coupled plasma atomic emission spectroscopy and energy dispersive spectrometer with Cu:Fe:Se = 0.96:1.00:1.99 consistent with the stoichiometric composition of CuFeSe2. The magnetic measurements suggest a ferrimagnetic or weak ferromagnetic transition below TC = 146 K and the resistivity reveals a semiconducting behavior and an abrupt increase below TC.

Nucleation-mediated growth of chiral 3D organic-inorganic perovskite single crystals.

Although their zero- to two-dimensional counterparts are well known, three-dimensional chiral hybrid organic-inorganic perovskite single crystals have remained difficult because they contain no chiral components and their crystal phases belong to centrosymmetric achiral point groups. Here we report a general approach to grow single-crystalline 3D lead halide perovskites with chiroptical activity. Taking MAPbBr3 (MA, methylammonium) perovskite as a representative example, whereas achiral MAPbBr3 crystallized from precursors in solution by inverse temperature crystallization method, the addition of micro- or nanoparticles as nucleating agents promoted the formation of chiral crystals under a near equilibrium state. Experimental characterization supported by calculations showed that the chirality of the 3D APbX3 (where A is an ammonium ion and X is Cl, Br or mixed Cl-Br or Br-I) perovskites arises from chiral patterns of the A-site cations and their interaction with the [PbX6]4- octahedra in the perovskite structure. The chiral structure obeys the lowest-energy principle and thereby thermodynamically stable. The chiral 3D hybrid organic-inorganic perovskites served in a circularly polarized light photodetector prototype successfully.

Phase formation in hole- and electron-doped rare-earth nickelate single crystals

The recent discovery of superconductivity in hole-doped infinite-layer nickelates has triggered a great interest in the synthesis of novel nickelate phases, which have primarily been examined in thin film samples. Here, we report the high-pressure optical floating zone growth of various perovskite and perovskite-derived rare-earth nickelate single-crystals and investigate the effects of hole-, electron-, and self-doping. For hole-doping with Ca and Sr, we observe phase separations during the growth process when a substitution level of 8% is exceeded. A similar trend emerges for electron-doping with Ce and Zr. Employing lower doping levels allows us to grow sizable crystals in the perovskite phase, which exhibit significantly different electronic and magnetic properties than the undoped parent compounds, such as decreased resistivity and a suppressed magnetic response. Our insights into the doping-dependent phase formation and the resulting properties of the synthesized crystals reveal limitations and opportunities for the exploration and manipulation of electronic states in rare-earth nickelates.

Wafer-Scale Epitaxial Growth of Two-dimensional Organic Semiconductor Single Crystals toward High-Performance Transistors.

The success of state-of-the-art electronics and optoelectronics relies heavily on the capability to fabricate semiconductor single-crystal wafers. However, the conventional epitaxial growth strategy for inorganic wafers is invalid for growing organic semiconductor single crystals due to the lack of lattice-matched epitaxial substrates and intricate nucleation behaviors, severely impeding the advancement of organic single-crystal electronics. Here, an anchored crystal-seed epitaxial growth method for wafer-scale growth of 2D organic semiconductor single crystals is developed for the first time. The crystal seed is firmly anchored on the viscous liquid surface, ensuring the steady epitaxial growth of organic single crystals from the crystal seed. The atomically flat liquid surface effectively eliminates the disturbance from substrate defects and greatly enhances the 2D growth of organic crystals. Using this approach, a wafer-scale few-layer bis(triethylsilythynyl)-anthradithphene (Dif-TES-ADT) single crystal is formed, yielding a breakthrough for organic field-effect transistors with a high reliable mobility up to 8.6 cm2 V-1 s-1 and an ultralow mobility variable coefficient of 8.9%. This work opens a new avenue to fabricate organic single-crystal wafers for high-performance organic electronics.

Growth, structural and optical analysis of sodium sulphamate single crystal for NLO applications

The slow evaporation solution growth technique (SEST) was used to successfully grow inorganic single crystals of sodium sulphamate (NaS) in ambient conditions. The titled crystal’s structural and optical characteristics were evaluated using a variety of spectroscopic techniques. Powder X-ray diffraction (PXRD) analysis and Fourier transform infrared (FT-IR) spectroscopy were used to examine the crystal structure characteristics. Using UV-Vis spectroscopy, the optical properties of the NaS crystal were carefully examined, and the optical bandgap was determined using Tauc’s plot. The HR-XRD analysis examined crystalline perfection. Additionally, photoluminescence spectroscopy determined the emission spectra, and time-resolved photoluminescence measured the decay rate. The [Formula: see text]-scan technique was also used to examine the titled crystal’s nonlinear optical (NLO) performance.

Growth and characterization of holmium-doped yttrium iron garnet single crystal

Yttrium iron garnet (YIG) crystals are the primary candidate for non-reciprocal device. With the miniaturization and integration of optical communication devices, the modified YIG crystals with excellent comprehensive performances are highly desired. To explore the possible mechanism of rare earth ions doping on Faraday effect, holmium oxide-doped YIG (Ho0.6Y2.4Fe5O12, abbreviated as HYIG) crystal was grown by molten salt method. Its structure, optical transparency, magnetic, magneto-optical properties and oxygen atmosphere annealing processes were first investigated systematically. The HYIG crystal wafers annealed at 800 °C for 2 h can achieve the large Faraday rotation angle (186 deg/cm at 1310 nm; 148 deg/cm at 1550 nm) and good optical transparency (73.64 % at 1310 nm; 74.83 % at 1550 nm), which is increased by approximately 10 % compared to the unannealed sample. This result may provide a new insight into the investigation of rare earth doped YIG crystals and their atmosphere annealing processes.

Investigation on the synthesis, growth, thermal and optical behavior of creatininium borate single crystal: A potential candidate for nonlinear optical applications

In the this study, we focus on the growth of a metal-organic creatininium borate (CRB) single crystal for third-order nonlinear optical (NLO) applications. Optically transparent & wide optical band gap single crystals of CRB were successfully harvested by adopting a slow evaporation solution technique (SEST) at a constant 40[Formula: see text]C temperature. The structural identification and lattice parameters of the grown sample were determined by powder X-ray diffraction (PXRD) using Rietveld analysis by FullProf Suite software. The occurrence of vacancy/interstitial defects produced during growth was investigated by high-resolution X-ray diffraction (HRXRD) using omega scan arrangement. A single peak with lower full width half maxima (56.4 arc s) was obtained from the scan which suggests that there were no grain boundaries for the grown crystal. Surface morphology and its features such as concentration of dislocations and defect sites on the as-grown sample were scrutinized using the etching technique. The optical band gap and UV–vis cut-off were examined and found to be 5.39 eV and 230 nm, respectively. Photoluminescence characteristics of the crystal show an emission at 377 nm upon excitation with a wavelength of 336 nm. The presence of radiative and non-radiative transitions inside the crystal due to excitation upon 266 nm laser was identified using time-resolved photoluminescence. Thermal stability and decomposition temperature of the compound were obtained by thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The third-order nonlinearity of the crystal was determined by Z-scan measurement technique with a femtosecond Ti-sapphire laser.

Thermodynamically and Kinetically Controlled Nucleation and Growth of Halide Perovskite Single Crystals.

Halide perovskites are ideal for next-generation optical devices and photovoltaics. Although perovskite single-crystals show reproducible optoelectronic properties, significant variations in the crystal size, anisotropy, density, defects, photoluminescence (PL), and carrier lifetime affect the sample properties and device performances. Homogenous size and shape FA/MAPbBr3 single microcrystals (MCs) with controlled edge lengths, crystal densities, PL lifetimes, and PL intensities are prepared by thermodynamically controlling and kinetically separating the crystal nucleation-growth processes using optimum N-cyclohexyl-2-pyrrolidone (CHP) concentration. The crystal growth kinetics at different CHP concentrations and temperatures are estimated spectroscopically by measuring the concentration of Pb (II). High-density cubic MCs with a homogenous size distribution, high PL intensities, and long PL lifetimes are obtained within minutes at high temperatures by the controlled addition of the pyrrolidone derivative. Conversely, the crystal size nonlinearly increases with time at low temperatures. The isotropically grown high-density single crystals at controlled nucleation-growth rates at 190°C with 20% CHP show the highest PL intensity and the longest PL lifetimes. This method offers thermodynamic and kinetic control of perovskite single-crystal growth with shape control.

Research on Single Crystal Preparation via Dynamic Liquid Phase Method

Traditional liquid phase methods for growing single crystals are static growth methods, which include seed crystal sedimentation growth and seed crystal clamping growth using seed crystal holders. Single crystals grown via seed crystal sedimentation often have a flat and elongated shape, and the region in contact with the bottom of the container is restricted during growth, resulting in significant defects. Similarly, the seed crystal clamping growth method cannot avoid contact with external objects, leading to abnormal growth at the contact points and along the direction of the seed crystal holder, also resulting in certain defects. Both of these growth methods require processes, such as cutting and grinding, to remove defects, resulting in resource waste. To address the shortcomings of the static liquid phase single-crystal preparation mentioned above, this study successfully designed a dynamic liquid phase method for single crystal growth, which achieved the successful suspension of seed crystals in the mother solution and the growth of high-quality, large-sized single crystals, avoiding contact with the walls and the bottom of the container during the crystal growth process. Based on the dynamic liquid phase single crystal growth apparatus mentioned above, stable and dynamic liquid phase preparation was successfully achieved, ranging from seed crystals with a diameter of approximately 5 mm to single crystals with a diameter of approximately 20 mm, by controlling the cooling rate and adjusting the solution flow rate.

Secondary Phase CeO2 Precipitates in Ce,Er-Doped Na0.5La0.5MoO4 Single Crystals Grown by Czochralski Method

Analytical scanning and transmission electron microscopy were used to study the microstructure of Ce,Er-doped Na0.5La0.5MoO4 laser crystals. Crystals were grown by the Czochralski method from the melts with a nominal composition of Na0.5La0.5−xCexEr0.005MoO4, where x = 0.125 and 0.15, then annealed at 700 and 1000 °C in the oxidizing atmosphere. We found the secondary phase precipitation of Ce2O3 oxide in as-grown crystals, while after high-temperature annealing the CeO2 precipitated crystals are always observed. Impurity ions Ce3+ occupy the La sites, and approximately 20% of the nominal Ce content is involved in the formation of Ce oxide secondary phase precipitates. The length of CeO2 precipitated crystals ranged between 100 nm and 550 nm (average length was 200 nm) and their width was 30–70 nm. The mechanism of CeO2 formation is discussed. The orientation relationships of Na0.5La0.5−xCexEr0.005MoO4/CeO2, the degree of coherence of the interface, and the preferential directions of their growth in the matrix were established. CeO2 crystals precipitated in the matrix cause light scattering with a wavelength comparable to the size of the precipitates and lead to deterioration of optical transparency of the material.

Influence of polar solvents on the growth and characteristic aspects of m-nitroaniline single crystals

Influence of polar solvents on the growth and characteristic aspects of m-nitroaniline single crystals

Growth and High-Performance Photodetectors of CsPbBr3 Single Crystals.

Organic-inorganic hybrid perovskites have demonstrated exceptional photovoltaic properties, making them highly promising for solar cells and photodetectors (PDs). However, the organic components of these materials are vulnerable to heat and strong light illumination, limiting their application prospects. All-inorganic cesium-based perovskite PDs, on the other hand, possess enhanced thermal tolerance and stability, making them ideal for perovskite applications. The utilization of a ternary mixture solvent and additives in combination with single crystal (SC) growth has enabled the production of highly crystalline SCs with a defect density of 3.79 × 109 cm-3. The performance of the SC PDs had been evaluated using metal-semiconductor-metal devices, which demonstrated excellent results with a dark current as low as 0.198 μA at 10 V bias, on-off ratios exceeding 103, and a response time of shorter than 1 ms.

Hydrogen-modulation method for wafer-scale few-layer single-crystal graphene growth

Single-crystal few-layer graphene films have potential applications in microelectronic and optoelectronic devices. Considerable efforts have been taken to prepare large-area bilayer graphene through chemical vapor deposition, but the growth of uniform graphene films with increased layers remains challenging. Herein, a hydrogen-modulation method for growing wafer-scale few-layer single-crystal graphene through chemical vapor deposition was proposed. By controlling the hydrogen flow rate at different stages, the dissolution amount and segregation process of carbon atoms in a CuNi substrate can be regulated separately. The hydrogen-modulation method fully exploits the effect of the dissolution–segregation mechanism, and the number of graphene layers can be controlled by modulating the hydrogen flow rate. Through the proposed method, the coverages of bilayer and trilayer graphene can reach more than 99% and 95%, respectively. The stacking and uniformity of few-layer graphene were evaluated by Raman and microstructure characterization, and bilayer and trilayer graphene were confirmed as AB and ABA stacks, respectively. Transmission line test structure and field effect transistor were prepared to verify the electrical properties of bilayer graphene. Results show that the square resistance of bilayer graphene is significantly lower than that of single-layer graphene, and it can also achieve high on-state current on field effect transistor.

Growth of single crystal Sb2S3 semiconductor pillars by sol-gel method

The binary compound semiconductor Sb2S3 was fabricated on solid substrate by spin coating based on a sol-gel method. In this study, it was observed that crystallinity appeared differently depending on the type of substrate material used to fabricate the Sb2S3 structure, and this mechanism was investigated. As the substrate, bare FTO glass and FTO glass coated with Mo, Ni, and Au were used. In the case of Sb2S3 grown on bare FTO glass and FTO glass coated with Mo, crystals are formed in-plane, whereas in the case of Sb2S3 grown on FTO glass substrate coated with FCC-structured metals such as Au and Ni, crystals are formed out-of-plane. It was observed that the single crystal growth of rectangular pillar-shaped Sb2S3 was closely related to the formation of regularly ordered compounds at the interface between the Sb2S3 pillar and the FCC metal substrate.

Exploring the potential of l-glutamic acid hydrochloride: growth, characterization, and applications in organic nonlinear optical single crystals for optoelectronic and photonic devices

Exploring the potential of l-glutamic acid hydrochloride: growth, characterization, and applications in organic nonlinear optical single crystals for optoelectronic and photonic devices

Theoretical insight on the optical centred electrical properties of guanidinium isophthalate NLO crystal for electro-optic Q switches

Guanidinium isophthalate single crystals with dimensions 16 × 4 x 2 mm3 were prepared by the low temperature solvent evaporation method and growth kinetics with interfacial tension was discussed to bring out the growth parameters of guanidinium isophthalate single crystals. The harvested single crystals were utilized for various characterization studies like powder X-ray diffraction, optical transmission, photoluminescence, laser damage study and optical limiting studies. The visualization of varying potential regions on the surfaces to quantify short contacts were generated by Hirshfeld surface analysis. 2D fingerprint plots were analyzed, in which H ….H contact was found to be the most significant with 54.1%. Growth kinetics of the crystalline material was studied to reveal the nucleation process. Crystal samples prepared with reference to the solubility data were found to be free of inclusions and cracks and had maximum transmittance in the complete visible region. The electronic disorder of the crystal sample was reported in the form of Urbach energy. The PL spectra with the emission intensity provide the emission characteristic of the title compound. The major fundamental optical limit for a crystal material is experimentally measured and presented in the picosecond regime. Thus the present work contributes to the understanding of growth, structural, optical and electronic characteristics of the title guanidinium isophthalate single crystals for the fabrication of electro-optic devices in photonic industry.

Cylindrical void growth vs. grain fragmentation in FCC single crystals: CPFEM study for two types of loading conditions

The crystal plasticity finite element method (CPFEM) is used to investigate the coupling between the cylindrical void growth or collapse and grain refinement in face-centred cubic (FCC) single crystals. A 2D plane strain model with one void is used. The effect of the initial lattice orientation, similarities, and differences between stress- and strain-driven loading scenarios are explored. To this end, boundary conditions are enforced in two different ways. The first one is based on maintaining constant in-plane stress biaxiality via a dedicated truss element, while the second one is imposing a constant displacement biaxiality factor. Uniaxial and biaxial loading cases are studied. For the uniaxial loading case a special configuration, which enforces an equivalent pattern of plastic deformation in the pristine crystal, is selected in order to investigate the mutual interactions between the evolving void and the developed lattice rotation heterogeneity. Next, biaxial loading cases are considered for three crystal orientations, one of which is not symmetric with respect to loading directions. It is analysed how stress or strain biaxility factors and initial lattice orientation influence the void evolution in terms of its size and shape. Moreover, the consequences of variations in the resulting heterogeneity of lattice rotation are studied in the context of the grain refinement phenomenon accompanying the void evolution. Scenarios that may lead to more advanced grain fragmentation are identified.