Bridgman Method Research Articles

The Bridgman method of (BiAs)2 (TeSe)3 bulk single crystal growth by spontaneous nucleation

The Bi0.5As1.5Te2.98Se0.02 single crystal in 11 mm?80 mm size was grown using the Bridgman method. Energy dispersive spectrometry (EDS) analysis was used to determine the chemical composition of the studied samples, as well as for checking and confirming the homogeneity of the samples. Mobility, concentration of charge majority carriers and Hall coefficient of single crystal, were determined using a Hall Effec system based on the Van der Pauw method. Hall Effect was measured at room temperature with four ohmic contacts and at temperature of liquid nitrogen with silver contacts with an applied magnetic field strength of 0.37 T at different current intensities. The expected improvement in the mobility of obtained single crystal doped with this content of arsenic was not obtained.

Моделирование напряженно-деформированного состояния кристалла, выращенного методом Бриджмена

The thermal stress in single crystal grown by Bridgman method is studied. The corresponding quasi-static problem of deformable solid mechanics is considered in axisymmetric case. The governing equations are approximated by finite element method. The effect of boundary conditions and material parameters on the stress-strain state of the single crystal is studied numerically.

Improving thermoelectric properties of p-type (BiSb)2(TeSe)3 single crystal by Zr doping

In order to study the effect of Zr doping on the thermoelectric properties of p-type Bi10.17Sb30.72 Zr0.35Te58.28Se0.48 single crystal, ?n ingot was prepared by Bridgman method. Cut and cleaved samples from different regions of ingot were characterized by a Hall Effect based on the Van der Pauw method. The first measurements were conducted with four ohmic contacts at room temperature and the obtained results were presented in our investigation, earlier. ?lso, high charge carriers mobility was obtained on the sample with silver contacts at the temperature of liquid nitrogen. Single crystal was characterized by Seebeck coefficient (S), conductivity (?) and resistivity (?) measurements as ? function of temperature in the range of 40-320?C by a home-made impedance meter. The prepared single crystal has a figure of merit (Z) of 1.22 x 10-3 K-1 at 300?C.

Single crystal growth of topological semimetals and magnetic topological materials

Topological materials have attracted much attention due to their novel physical properties. These materials can not only serve as a platform for studying the fundamental physics, but also demonstrate a significant potential application in electronics, and they are studied usually in two ways. One is to constantly explore new experimental phenomena and physical problems in existing topological materials, and the other is to predict and discover new topological material systems and carry out synthesis for further studies. In a word, high-quality crystals are very important for studying quantum oscillations, angle resolved photoemission spectra or scanning tunneling microscopy. In this work, the classifications and developments of topological materials, including topological insulators, topological semimetals, and magnetic topological materials, are introduced. As usually employed growth methods in growing topological materials, flux and vapour transport methods are introduced in detail. Other growth methods, such as Bridgman, float-zone, vapour deposition and molecular beam epitaxy methods, are also briefly mentioned. Then the details about the crystal growth of some typical topological materials, including topological insulators/semimetals, high Chern number chiral topological semimetals and magnetic topological materials, are elaborated. Meanwhile, the identification of crystal quality is also briefly introduced, including the analysis of crystal composition and structure, which are greatly important.

Single crystal growth of topological semimetals and magnetic topological materials

Topological materials have attracted much attention due to their novel physical properties. These materials can not only serve as a platform for studying the fundamental physics, but also demonstrate a significant potential application in electronics, and they are studied usually in two ways. One is to constantly explore new experimental phenomena and physical problems in existing topological materials, and the other is to predict and discover new topological material systems and carry out synthesis. In a word, high-quality crystals are very important for studying quantum oscillations, angle resolved photoemission spectra or scanning tunneling microscopy. In this work, the classifications and developments of topological materials, including topological insulators, topological semimetals, and magnetic topological materials, are introduced. As usually employed growth methods in growing topological materials, flux and vapour transport methods are introduced in detail. Other growth methods, such as Bridgman, float-zone, vapour deposition and molecular beam epitaxy methods, are also briefly mentioned. Then the details about the crystal growth of some typical topological materials, including topological insulators/semimetals, high Chern number chiral topological semimetals and magnetic topological materials, are elaborated. Meanwhile, the identification of crystal quality is also briefly introduced, including the analysis of crystal composition and structure, which are greatly important.

Effects of excess Te on the optical and electrical properties of Cd1−xMgxTe single crystals grown by the modified vertical Bridgman method

Diagram of crystal growth process for Cd0.95Mg0.05Te ingots. Three large Cd0.95Mg0.05Te ingots with diameter of 30 mm and length of more than 100 mm are successfully grown by the modified vertical Bridgman method under different excess Te conditions.

Effect of orientation of NiSb needle inclusions on temperature dependence of resistance in Cd-=SUB=-0.95-=/SUB=-Ni-=SUB=-0.05-=/SUB=-Sb crystals

A composite Cd0.95Ni0.05Sb crystal consisting of CdSb and NiSb inclusions was obtained by the modified Bridgman method. It was shown by the methods of scanning electron microscopy, X-ray phase analysis, energy-dispersive X-ray spectroscopy, and studies of Raman spectra, that the main CdSb matrix was a block single crystal (orthorhombic Pbca structure) containing microcrystalline acicular inclusions of the second NiSb phase (hexagonal structure of the NiAs type P63/mmc). It has been found that the anisotropy of single-crystal NiSb needles in samples of the Cd0.95Ni0.05Sb crystalline composite (needles are directed along and across the current direction) significantly affects the resistance and magnetoresistance of the crystal. The interface is a needle-like inclusion --- the matrix can become superconducting, which affects the conductivity of the composite as a whole. However, this superconductivity is insufficient for the transition at the experimental temperatures to the superconducting phase with zero resistance of the composite. Keywords: cadmium antimonide, nickel antimonide, composite, anisotropy of conductivity, interface superconductivity.

Synthesis, structure and characterization of Cd2TeO3Cl2 with unprecedented [Cd2O6Cl4] octahedral dimers.

A new mixed anionic compound Cd2TeO3Cl2 with unprecedented [Cd2O6Cl4] octahedral dimers has been synthesized, and millimeter-scale single crystals of Cd2TeO3Cl2 have been grown by the vertical Bridgman method with CdCl2 as the flux. Cd2TeO3Cl2 crystallizes in the centrosymmetric P1̄ (no. 2) space group, and shows a mixed cationic layer structure constituted by distorted [TeO3] motifs, mixed anionic [Cd2O6Cl4] chains, and [Cd2O6Cl4] octahedral dimers. Experimental and theoretical results show that Cd2TeO3Cl2 is a direct band gap compound with an experimental band gap of ∼4.25 eV. Meanwhile, the compound has good optical transmittance in the 3-5 μm atmospheric window. The results indicate that Cd2TeO3Cl2 could be used as a promising mid-IR window material, and could enrich the chemical and structural diversity of oxides.

Влияние ориентации игольчатых включений NiSb на температурную зависимость сопротивления в монокристаллах Cd-=SUB=-0.95-=/SUB=-Ni-=SUB=-0.05-=/SUB=-Sb

A composite Cd0.95Ni0.05Sb crystal consisting of CdSb and NiSb inclusions was obtained by the modified Bridgman method. It was shown by the methods of scanning electron microscopy, X-ray phase analysis, energy-dispersive X-ray spectroscopy, and studies of Raman spectra, that the main CdSb matrix was a block single crystal (orthorhombic Pbca structure) containing microcrystalline acicular inclusions of the second NiSb phase (hexagonal structure of the NiAs type P63/mmc). It has been found that the anisotropy of single-crystal NiSb needles in samples of the Cd0.95Ni0.05Sb crystalline composite (needles are directed along and across the current direction) significantly affects the resistance and magnetoresistance of the crystal. The interface is a needle-like inclusion - the matrix can become superconducting, which affects the conductivity of the composite as a whole. However, this superconductivity is insufficient for the transition at the experimental temperatures to the superconducting phase with zero resistance of the composite.

Anisotropic X-ray detection performance of melt-grown CsPbBr3 single crystals

The investigation of the anisotropic X-ray detection performance of bulk CsPbBr3 single crystals grown by the vertical Bridgman method.

Stabilization of the Polar Structure and Giant Second‐Order Nonlinear Response of Single Crystal γ‐NaAs0.95Sb0.05Se2

AbstractThe dearth of suitable materials significantly restricts the practical development of infrared (IR) laser systems with highly efficient and broadband tuning. Recently, γ‐NaAsSe2 is reported, and it exhibits a large nonlinear second‐harmonic generation (SHG) coefficient of 590 pm V−1 at 2 µm. However, the crystal growth of γ‐NaAsSe2 is challenging because it undergoes a phase transition to centrosymmetric δ‐NaAsSe2. Herein, the stabilization of non‐centrosymmetric γ‐NaAsSe2 by doping the As site with Sb, which results in γ‐NaAs0.95Sb0.05Se2 is reported. The congruent melting behavior is confirmed by differential thermal analysis with a melting temperature of 450 °C and crystallization temperature of 415 °C. Single crystals with dimensions of 3 mm × 2 mm are successfully obtained via zone refining and the Bridgman method. The purification of the material plays a significant role in crystal growth and results in a bandgap of 1.78 eV and thermal conductivity of 0.79 Wm−1 K−1. The single‐crystal SHG coefficient of γ‐NaAs0.95Sb0.05Se2 exhibits an enormous value of |d11| = 648 ± 74 pm V−1, which is comparable to that of γ‐NaAsSe2 and ≈20× larger than that of AgGaSe2. The bandgap of γ‐NaAs0.95Sb0.05Se2 (1.78 eV) is similar to that of AgGaSe2, thus rendering it highly attractive as a high‐performing nonlinear optical material.

Crystal growth and scintillation characterizations of mixed halide scintillators K2LaBr5-xIx: Ce (x = 0, 1, 2)

The purpose of this research is to investigate the luminescence and scintillation properties of mixed halide scintillators K2LaBr5-xIx. The crystals of K2LaBr5-xIx:2% Ce (x = 0, 1, 2) have been synthesized by high-temperature solid-phase method and grown by vertical Bridgman method. The crystals are measured by X-ray induced luminescence spectra, optical transmittance photoluminescence spectrum, photoluminescence decay time, and pulse height spectrum. Under the UV and X-ray excitation, all of the crystal samples have typical Ce3+ double peaks corresponding to the energy level shifts of 5d1→2F5/2 and 5d1→2F7/2, with emission centers ranging from 350 to 400 nm. The photoluminescence decay time of the three crystals of K2LaBr5-xIx: Ce is about 20 ns. Under 662 keV γ-rays excitation from a 137Cs source, the energy resolution is 8.2%, 15% and 10% (FWHM), respectively.

Growth and characterization of IR nonlinear optical PbIn6Te10 crystal

The crack-free PbIn6Te10 single crystal with ϕ28 mm × 90 mm was grown by the modified Vertical Bridgman method. Experimental results show that the main body of the boule is a PbIn6Te10 single crystal, while the tail has a certain amount of PbTe and Te. The measurements of UV and IR transmission demonstrate that the transmittance of PbIn6Te10 in 3.5–5.0 µm and 8–12 µm is more than 57 % and the corresponding absorption coefficient is in the range of 0.1–0.3 cm−1. The electrical properties of PbIn6Te10 crystal were studied within 50–300 K by temperature-dependent Hall-effect measurement. It is found that the as-grown crystal is an N-type semiconductor, and the carrier concentration varies nearly exponentially duo to the donor impurity ionization in the measured temperature range. Furthermore, the donor impurity ionization energy ∇ED was evaluated to be 0.04779 eV, and the fitted carrier mobility μH ∝ T−3/2 reveals the primary scattering mechanism within 170–300 K is the lattice vibration scattering.

Impact of Br-doping on the optical and optoelectronic properties of CsPbCl3 crystals

The all-inorganic halide perovskite CsPbX3 (X = I, Br and Cl) with outstanding optoelectronic properties and is expected to be the next generation of optoelectronic detection materials. However, the CsPbCl3 crystal is difficult to grow by low-temperature solution method. Here, we report a series of Br-doped CsPbCl3 crystals by Vertical Bridgman method. Crystal structure, spectra properties and photoelectric performances of CsPbCl3-xBrx single crystals were studied systematically. Photoluminescence (PL), X-ray excited luminescence (XEL) and UV–vis spectra can be tuned by Br-doped in the CsPbCl3 crystals. Furthermore, the basic photoelectric properties were investigated for Br-doped CsPbCl3 crystals and the optimum component of CsPbBr2.64Cl0.36 crysatal displays the highest resistivity of 2.8 × 109 Ω cm, and an on/off ratio of ∼ 25. Our work provides a feasible strategy for optimizing the photoelectric properties of doped halide perovskite crystal.

Fabrication and Characterization of K2CeCl5/6LiCl and CeCl3/SrCl2/6LiCl Eutectics for Thermal Neutron Detection

In recent years, thermal neutron detection using scintillators has been used in a wide range of fields. Thus, the development of scintillators with a higher light yield, faster decay, and higher sensitivity for thermal neutrons is required. In this study, K2CeCl5/6LiCl and CeCl3/SrCl2/6LiCl were developed as novel eutectic scintillators for thermal neutron detection. LiCl was selected as the neutron capture phase and K2CeCl5 and CeCl3 were used as the scintillator phases. The eutectics of K2CeCl5/6LiCl and CeCl3/SrCl2/6LiCl were prepared using the Vertical Bridgman method and the phases were identified by scanning electron microscopy and powder X-ray diffraction measurements. The results of radioluminescence measurements under Ag source X-ray tube irradiation confirmed that the 5d-4f emission derived from Ce3+. The cathodoluminescence spectra and thermal neutron responses of the prepared eutectics were measured to evaluate their optical properties.

Influence of Air Annealing on Optical and Scintillation Properties of YAG:Pr,Ca

Single crystals of yttrium aluminum garnet (YAG) with Pr3+ and Ca2+ ions grown by the vertical Bridgman method are submitted to air anneal. The influence of this process on optical absorption, photo‐, and radioluminescence is investigated in a set of samples with different concentrations of Pr and Ca. Absorption induced by the heat treatment in the 300–600 nm range in YAG:Pr,Ca is discussed, in comparison with that in YAG:Ca crystals. Photo‐ and radioluminescence spectra in as‐grown and air‐annealed samples recorded at room temperature are discussed. The features of emission decrease at 5d–4f and 4f–4f transitions of Pr3+ ions after heat treatment are considered.

Effect of doping and annealing on resistivity, mobility-lifetime product, and detector response of (Cd,Mn)Te

We present the effect of doping with In, V, and Cl on the values of resistivity (ρ) and mobility-lifetime (μτ) in (Cd,Mn)Te crystals grown by the Bridgman method and with diameters of 2 or 3 in. This material is investigated to use in room-temperature X-ray and gamma-ray detectors. We carried out post-growth annealing processes in cadmium vapors at 500 °C to obtain more homogeneous crystal properties. The EU-ρ-μτ-SCAN machine, which uses the principle of time-dependent charge measurement, allowed us to map the values of resistivity and mobility-lifetime in crystal plates. High values of those two quantities are crucial in nuclear detector applications. Crystals doped with In show inhomogeneous properties, which makes the fabrication of competitive large-area crystals more difficult. Low-temperature post-growth annealing in Cd vapors is insufficient for (Cd,Mn)Te:In crystals, where the decrease of ρ and μτ values is observed. Such annealing works for (Cd,Mn)Te:V crystals, where the mean values of ρ and μτ do not change significantly, but their distributions are more uniform. Both dopants, vanadium and indium, used together with an excess of Te, effectively increased ρ and μτ. Using the 57Co source, the spectroscopic performance of each pixel of the detector co-doped with In and V was shown.

Analysis of grain growth behavior of multicrystalline Mg2Si

Multicrystalline Mg2Si crystal with a diameter of 15 mm was grown via vertical Bridgman method. To clarify the growth mechanism of the multicrystalline structure, the grain growth behavior of the crystal was analyzed. This was carried out through segmenting grains by mean shift clustering using the light intensity profile obtained from multiple optical reflection images of the wafers and stacking the segmented images through the growth direction. Further crystal orientation measurement revealed that a grain with a higher surface energy competitively expanded to the lateral direction during crystal growth. We speculated that the growth behavior occurred because the supercooling was high enough to show difference in each grain’s growth rate. This idea was supported by crystal growth simulation to show a tendency for the crystallization rate to increase toward the latter half growth stage, which is consistent with the assumption for crystal growth with high supercooling.

Temperature dynamic compensation vertical Bridgman method growth of high-quality GaSb single crystals

Gallium antimonide (GaSb) is considered an ideal substrate for heterostructure growth. A significant property that inhibits the widespread application of infrared plane-array detector growth on GaSb is the crystal quality of the starting substrate. Herein, we report the growth of single-crystal GaSb by a temperature dynamic compensation vertical Bridgman (TDC-VB) method. This approach offers a low temperature gradient and a stable solid–liquid interface position in the furnace during the growth process. Two inch diameter twin-free GaSb single crystals with (100) orientation have been reproducibly obtained using the TDC-VB method. The crystalline character of the obtained GaSb has been examined by optical microscopy (OM), high-resolution X-ray diffraction (HRXRD), X-ray tomography (XRT), and Fourier-transform infrared (FTIR) spectroscopy. The etch pit dislocation density (EPD) of the GaSb polished wafers (100) was 6–72 cm−2, and the full-width at half-maximum (FWHM) of the Bragg diffraction peak was 15.4″. A uniform XRT image was obtained, and ca. 50 % of the GaSb wafers, which were produced by one crystal, showed transmittance > 20 % at 10 µm, indicating the formation of high-quality GaSb crystals. This work provides useful guidelines for the formation of high-quality GaSb crystals with significant promise for substrate applications.

Relevance of Solidification Kinetics for Enhanced Thermoelectric Performance in Al-Doped Higher Manganese Silicides.

The solidification kinetics of an alloy from its liquid state forms an underlying basis for microstructural engineering, wherein the state of thermodynamic equilibrium associated with the melt-grown crystal and the quenched amorphous solid denotes the two limits for crystallinity in the alloy synthesis. In this study, we report the implication of the crystalline state on the thermal and electrical transport properties of partially substituted Mn(Si1-xAlx)γ by comparing the single crystals melt-grown by the Bridgman method, and polycrystals synthesized from melt spinning (MS) and subsequent spark plasma sintering (SPS). The rapidly solidified alloys exhibited nanocrystalline microstructures in MS ribbons, while melt-grown single crystals displayed characteristics evolution of MnSi striations with limited solubility of Al. It was observed that Al as a p-type dopant enhances the carrier concentration and electrical conductivity, while nanocrystallinity in MS + SPS polycrystals and secondary phases in monocrystals were effective in enhancing the phonon scattering. Maximum zT values of ∼0.54 (±0.05) at 823 K and 0.75 (±0.05) at 873 K were attained for the single crystal (directed perpendicular to the c-axis) and melt-spun polycrystals (along the in-plane direction), respectively. These results present the efficacy of aliovalent Al substitution and demonstrate the critical role of the solidification kinetics in optimizing the carrier concentration and enhancing the phonon scattering in higher manganese silicide crystals for thermoelectric applications.