Bridgman Stockbarger Research Articles

Sustained hydrogen production through alkaline water electrolysis using Bridgman–Stockbarger derived indium-impregnated copper chromium selenospinel

The depletion of conventional fossil fuels necessitates the development of sustainable energy alternatives, with electrochemical water splitting for hydrogen (H2) production being a promising solution. However, large-scale hydrogen generation is hindered by the scarcity of cost-effective electrocatalysts to replace noble metals such as Pt and RuO2 in the Oxygen Evolution Reaction (OER) and Hydrogen Evolution Reaction (HER). In this study, we report the synthesis of CuCr2-xInxSe4 (x = 0, 0.2, 0.4) using a dual approach combining the Bridgman-Stockbarger method and ball milling. Among the synthesized materials, CuCr1.8In0.2Se4 demonstrates outstanding HER activity in 1.0 M KOH, achieving a potential of −0.16 V vs. RHE at a current density of 10 mA cm−2. Moreover, the material shows remarkable durability during a three-electrode accelerated degradation test in an alkaline medium, maintaining its performance over 24 h at a constant current density of −200 mA cm−2, with a stable potential of −0.57 V vs. RHE. Additionally, CuCr1.8In0.2Se4 was tested in a two-electrode configuration alongside CoFe LDH, achieving a benchmark of 1.7 V for overall water splitting. It sustained a current density of 400 mA cm−2 for 24 h in an accelerated degradation test, exhibiting a minimal loss of 0.1 V after the testing period. These results highlight CuCr1.8In0.2Se4 as a promising non-noble metal catalyst for HER, demonstrating its potential to reduce reliance on noble materials for large-scale hydrogen production.

Thermal Field Simulation and Optimization of PbF2 Single Crystal Growth by the Bridgman Method

PbF2 single crystals are usually grown in the temperature gradient region by the Bridgman–Stockbarger method. Temperature distribution during the growth process is particularly important for the preparation of high-quality crystals. In this study, the temperature field during the growth of the PbF2 single crystals was simulated based on the finite element method. The temperature distribution and temperature gradient changes in the crucible were investigated at different growth stages, including the seeding, shouldering, and iso-diameters stages. The calculated results show that as the crucible position continues downward during the growth process, the axial temperature gradient increases and then decreases from the bottom to the top of the crucible, with almost flat isotherms near the solid–liquid interface where the axial temperature gradient is larger. At the shoulder below the crucible, the solid–liquid interface was improved by adjusting the tilt angle. Furthermore, based on a novel design of the heat-insulating baffle, the concave solid–liquid interface in the iso-diameter stage can be effectively adjusted to realize a lower radial temperature gradient. This study provides theoretical guidance for the optimization of the growth of high-quality PbF2 crystals by the Bridgman method.

Scintillation properties of In-doped NaI transparent ceramics

In-doped NaI transparent ceramic scintillators were synthesized by the spark plasma sintering method, and In-doped NaI single crystal was grown by the Bridgman–Stockbarger method. The diffuse transmittance at the emission wavelength was ∼70% for the transparent ceramics and ∼90% for the single crystal. In the scintillation spectra under X-ray irradiation, emission peaks were observed at around 320, 460, and 510 nm in both of the transparent ceramic and single crystal samples. The peaks at 460 and 510 nm are due to 3P1 →1S0 transitions of In+. The decay time constants of the transparent ceramics and the single crystal were 1.8 μs. The X-ray induced afterglow level of the 0.1% In-doped NaI transparent ceramic and the single crystal was 170 and 777 ppm, respectively. In pulse height analysis, 662 keV photoabsorption peaks were clearly observed in all the samples when irradiated with 137Cs γ-rays. The light yield of the 0.1% In-doped NaI transparent ceramic was 19,000 ph/MeV, and that of the 0.1% In-doped NaI single crystal was 12,000 ph/MeV. The transparent ceramics showed better scintillation properties than the single crystal.

Optimizing the temperature gradient for CdZnTe crystal growth using the vertical Bridgman–Stockbarger method

CdZnTe (CZT) is considered an ideal material for the growth of HgCdTe (MCT) epitaxial layers and nuclear detection devices. The crystal quality of CZT is the key factor in the MCT-based infrared plane array and the performance of nuclear devices. Herein, we report the growth of CZT by optimizing the temperature gradient vertical Bridgman–Stockbarger method. The crystalline character of the obtained CZT has been examined using optical microscopy, IR transmission microscopy, high-resolution X-ray diffraction, X-ray tomography (XRT), Fourier-transform infrared spectroscopy and glow discharge mass spectrometry. The etch pit dislocation density of the CZT sliced wafers (111)-B was less than 4.0 × 103 cm−2, the triangular shape inclusions in the CZT volume of the double-grinding wafers have a sparse distribution, and the size can be controlled to be less than 5 μm, the typical full-width at half-maximum of the Bragg diffraction peak was 17.4″. The XRT image of polished CZT wafers (111)-B showed a uniform structure without strain and defects. About 100 % of the CZT wafers showed transmittance >50 % at 20 µm and the detected impurities in the crystal were low, Li 4.9 ppb and Na 2.9 ppb, indicating the formation of high-quality CZT crystals. This work provides a scheme to improve the crystal quality of CZT for high-performance device applications.

Growth and Scintillation Properties of 6Li Containing Ce:LaCl3-Based Eutectic Scintillator for Neutron Detection

In this study, Ce:6LiCl/LaCl3 with a high 6Li concentration was developed as a novel thermal neutron scintillator, in which Ce3+ serves as an activator for the LaCl3 phase. The Ce:6LiCl/LaCl3 eutectic was grown in a quartz ampoule (inner diameter: 4.0 mm) using the Bridgman–Stockbarger technique. The grown eutectic contained 0.038 mol/cm3 6Li, which is greater than that found in commercially available scintillators such as LiCaAlF6 single crystals and Li glass. The Ce:6LiCl/LaCl3 eutectic has a lamellar eutectic structure and is optically transparent. A 350 nm emission due to Ce3+ 4f-5d transition was observed. The light yield under neutron irradiation was estimated to be 5.0 times higher than that of Li-glass. In this eutectic, the 6Li (n, a) 3H reaction made the 6LiCl phase to act as the neutron capture phase and LaCl3 to act as the scintillator phase.

Optical Temperature Sensors Based on Down-Conversion Nd3+,Yb3+:LiYF4 Microparticles

Nd3+ (0.3 mol.%), Yb3+ (0, 1, 2, 3 and 5 mol.%): LiYF4 phosphors were grown by the Bridgman–Stockbarger technique. The luminescence intensity ratio (LIR) of Nd3+ (4F3/2–4I9/2, ~866 nm) and Yb3+ emission (2F5/2–2F7/2, ~980 nm) was taken as a parameter. The energy exchange between 4F3/2 (Nd3+) and 2F5/2 (Yb3+) occurs via phonons, which elucidates the LIR temperature dependence. The influence of the cross-relaxation process on the temperature sensitivity was estimated as negligible. The LIR function depends on the Yb3+ concentration at a fixed 0.3 mol.% Nd3+. The maximum Sa and Sr value were reached for Nd3+ (0.3%), Yb3+ (1.0%): LiYF4 (Sa = 0.007 K−1 at 320 K) and Nd3+ (0.3%), Yb3+ (5.0%): LiYF4 (Sr = 1, 1.03%*K−1 at 260 K), respectively.

Thermal Stability of LiRF4 (R = Gd, Tb) Compounds

AbstractLiGdF4 and LiTbF4 single crystals are grown by the Bridgman–Stockbarger method from the nonstoichiometric melt comprising 32 mol% RF3 (R = Gd, Tb) and 68 mol% LiF, respectively. Incongruent melting of the single crystals LiGdF4 and LiTbF4 is confirmed by differential scanning calorimetry. For the first time, the crystal structures of LiGdF4 and LiTbF4 are determined by Rietveld method. Also, rare‐earth lithium fluoride syntheses from lithium nitrate melts at 400 °С are performed for LiTbF4, LiGdF4, LiYF4, and LiDyF4 compounds. For terbium, the product is a mixture of LiTbF4 and TbF3; and for gadolinium, GdF3 is thus produced. With reference to the related literature, it is concluded that LiGdF4 and LiTbF4 are the thermodynamically stable phases in the ranges from 750 ± 5 to 425 ± 15 °С, and from 782 ± 5 to 400 ± 15 °С, respectively. The metastability of LiGdF4 and LiTbF4, however, does not prevent the use of their single crystals as photonic materials.

Differential-thermal analysis and a microscopic study of the effect of γ-radiation on CuTlSe2 single crystal

Herein, the X-ray phase analysis (XPA) and differential-thermal analysis (DTA) of the CuTlSe2 compound obtained by the Bridgman–Stockbarger method have been investigated. As a result of the study, the values of energy absorption and mass losses of CuTlSe2 single crystal have been estimated depending on the temperature given their change mechanisms. The surface morphology of single crystals of the ternary coppercopounds (Cu-Tl-X ([Formula: see text])) in the initial state, annealing and after exposure to gamma-radiation is studied by atomic force microscopy. It is shown that the surface relief undergoes modification in the absorbed dose region of [Formula: see text] 500[Formula: see text]krad.

X-Ray and Morphological Analysis of InAs-CrAs Eutectic Nanocomposite Systems

InAs-CrAs systems are synthesized by the vertical Bridgman–Stockbarger method. XRD analysis and microstructural study of InAs-CrAs composites show that CrAs metallic inclusions are uniformly distributed in the InAs matrices. By investigating of microstructure of InAs-CrAs eutectic composite by electron microscope, it has been established that the interfacial zone between the semiconductor matrix and metallic inclusions is generated. In computations of effective electrical and thermal conductivity of the composite were taken into account the role of these interfacial zones.

Growth and characterization of optical and thermal properties of LiGdF4 single crystal

The opportunity of growing of several centimeters in length LiGdF4 single crystals by Bridgman–Stockbarger technique was demonstrated and the optically perfect LiGdF4 single crystals with 8 mm and 55 mm in length were grown. The phase composition, thermal conductivity, basic optical and spectral-kinetic properties of LiGdF4 single crystals were studied for the first time. For LiGdF4 crystal, the resulting linear thermal expansion coefficients α is 11% larger, than for both LiYF4 and LiYbF4 crystals. The obtained thermal conductivity dependence k(T) is more pronounced compared to LiLuF4 and LiYF4. The absorption spectrum of the LiGdF4 crystal shows absorption bands corresponding to the 8S7/2 – (6Dj, 6Ij, and 6Pj) transitions of Gd3+ ions. The measured room temperature lifetime of 6Pj multiplet of Gd3+ ions was equal to 4.25 ± 0.05 ms. The values of the temperature gradient of the LiGdF4 refractive index do not strongly depend on the wavelength.

Study of the Thermal Properties and Lattice Disorder Effects in CdTe–Based Crystals: CdBeTe, CdMnTe, and CdZnTe

Mixed semiconductor ternary crystals were grown using the Bridgman–Stockbarger method. This is a high–temperature and high–pressure crystal growth method. Cd1–xBexTe crystals were grown in the range of composition 0 < x < 0.1, such as 0.00, 0.01, 0.03, 0.05, and 0.1. The main goal of this paper was to compare the thermal properties of CdBeTe with previously grown CdMnTe and CdZnTe–mixed ternary crystals. The photopyroelectric technique was applied to examine the thermal properties. The thermal diffusivity and effusivity values were obtained after testing all the samples, and the thermal conductivity was calculated then. As such, a complete thermal characterization of the crystals was carried out. For further characterization, the thermal conductivity versus composition was checked by applying the Sadao Adachi model. Thanks to that, we were able to determine the total thermal resistivity of the crystals and the additional resistivity which arises from the lattice disorder. As such, the disorder effects arising from substituting the native atom with a foreign one were characterized for all crystals. We were looking for the best substitution of the Cd atom in the CdTe matrix based on the compounds’ thermal properties. It turned out that Zn and Mn introduce a similar disorder, with Be being the highest one.

Comparative pulse shape discrimination study for Ca(Br, I)[formula omitted] scintillators using machine learning and conventional methods

In particle physics experiments, pulse shape discrimination (PSD) is a powerful tool for eliminating the major background from signals. However, the analysis methods have been a bottleneck to improving PSD performance. In this study, two machine learning methods—multilayer perceptron and convolutional neural network—were applied to PSD, and their PSD performance was compared with that of conventional analysis methods. Three calcium-based halide scintillators were grown using the vertical Bridgman–Stockbarger method and used for the evaluation of PSD. Compared with conventional analysis methods, the machine learning methods achieved better PSD performance for all the scintillators. For scintillators with low light output, the machine learning methods were more effective for PSD accuracy than the conventional methods in the low-energy region.

Physical-chemical properties of InSb+Mg3Sb2 eutectic systems: synthesis, characterization, and applications

InSb+Mg3Sb2 systems are synthesized by the vertical Bridgman–Stockbarger method. InSb and Mg3Sb2, a form of lamellar eutectic. XRD analysis and microstructural study of InSb+Mg3Sb2 composites show that Mg3Sb2 lamellar are uniformly distributed in the InSb matrices. The initial and final melting temperatures for InSb+Mg3Sb2 eutectic alloys are 770K and 772K, respectively.

Scintillation property of undoped NaI transparent ceramics

In this study, NaI transparent ceramics were synthesized by the spark plasma sintering method, also optical and scintillation properties were investigated. To evaluate the potential of the transparent ceramics, a NaI single crystal was also prepared by the vertical Bridgman–Stockbarger method. The diffuse transmittance of the transparent ceramic fabricated at 470 °C was equivalent to that of the single crystal. All the samples showed scintillation peaking at 320 nm due to self-trapped exciton. In addition, scintillation peaks ascribed from lattice defects were detected at 450 nm for the transparent ceramics and 540 nm for the single crystal. The scintillation decay time constants of the transparent ceramic fabricated at 440 °C were 5.7, 18, and 189 ns. The light yield of the transparent ceramic turned out to be 910 photons MeV−1 and was two-thirds of the single crystal.

Anisotropic Thermal Expansion and Electronic Structure of LiInSe2.

Optical quality cm-sized LiInSe2 crystals were grown using the Bridgman–Stockbarger method, starting from pure element reagents, under the conditions of a low temperature gradient of 5–6 degrees/cm and a slight melt overheating. The phase purity of the grown crystal was verified by the powder XRD analysis. The thermophysical characteristics of LiInSe2 were determined by the XRD measurements in the temperature range of 303–703 K and strong anisotropy of the thermal expansion coefficients was established. The following values of thermal expansion coefficients were determined in LiInSe2: αa = 8.1 (1), αb = 16.1 (2) and αc = 5.64 (6) MK−1. The electronic structure of LiInSe2 was measured by X-ray photoelectron spectroscopy. The band structure of LiInSe2 was calculated by ab initio methods.

A Quintuple-Layered Binary Chalcogenide Sb2Te3 Single Crystal and Its Transport Properties for Thermoelectric Applications.

The binary chalcogenide material Sb2Te3 was synthesized via the melting technique. The synthesized materials were converted to a single crystal through the Bridgman–Stockbarger technique. The phase purity and structural properties of the grown crystal were analyzed using powder X-ray diffraction and single-crystal X-ray diffraction measurements. X-ray photoemission spectroscopy reveals the local intermolecular bonding, changes in the stoichiometry, and the oxidation states of the elements present in the crystal. Transport properties like electrical resistivity, Seebeck coefficient, and thermal conductivity were measured. The power factor and figure of merit (ZT) of the grown crystal were calculated.

Growth of thallium-doped CsI/CsCl/KCl eutectics and their scintillation properties

In this study, Tl:CsI/CsCl/KCl ternary eutectic scintillators were grown using the vertical Bridgman–Stockbarger method by unidirectional solidification. The CsI and KCl phases were elongated along the growth direction, based on backscattered electron imaging (BEI) observations. The Tl:CsI scintillator phase grew as a matrix, which can be used to create optical waveguides for scintillation light. The expected Tl+ emission peak was observed at 550 nm under X-ray excitation. This emission was attributed to the self-trapped excitons perturbed by TI+ in Tl:CsI. The decay time of the Tl:CsI/CsCl/KCl eutectic was 285 ns, and its light output was estimated to be 10,800 photons/MeV.

Piezomodulation of electrical conductivity in TlIn0.9Ga0.1Se2 single crystals

In the present work, the piezoelectric properties of TlIn[Formula: see text]Ga[Formula: see text]Se2 single crystals are investigated. Single crystals were grown by the Bridgman–Stockbarger method. The results show that when periodic mechanical vibrations are excited in these crystals, the electrical conductivity is modulated at the same frequency. Measurements of the amplitude values of the piezoconductivity at the same degree of deformation in the dark and under different illumination revealed the presence of a linear relationship between them. The level of the piezosignal also changes linearly depending on the strength of the magnetic field. Thus, TlIn[Formula: see text]Ga[Formula: see text]Se2 crystals have a potential prospect of application in the field of highly sensitive magnetic and light sensors.

Photoelectric properties of TlGaxIn1−xSe2 (x = 0 − 1) single crystals

This work presents the results of a study of the photoelectric properties of single crystals of the TlGa[Formula: see text]In[Formula: see text]Se2 system of solid solutions based on TlInSe2 with high photo and tensile sensitivity and switching properties with memory and TlGaSe2 with high photosensitivity in the visible and infrared regions of the spectrum. Single crystals of the above alloys were grown by the Bridgman–Stockbarger methods. Investigated alloys correspond in [Formula: see text], 0.1, 0.2, 0.3, 0.4, 0.7, 0.8, 0.9, 1 compounds. It was revealed that these alloys are photosensitive materials, and with a decrease in [Formula: see text] from 1 to 0, a shift of the spectral characteristic maxima from 0.57[Formula: see text][Formula: see text]m to 1.35[Formula: see text][Formula: see text]m is observed. The specific resistance at 77–300 K and the bandgap of the investigated phases have been determined. It was found that with an increase in the content of Ga in the composition of solid solutions, the bandgap increases from 1.23 eV to 2.15 eV.

Fermi energy-level shift of p-type AgBiSe2 single crystal featuring semiconductor-to-metal transition at cryogenics

A ternary chalcogenide AgBiSe2 (ABS) crystal was grown using the Bridgman–Stockbarger technique followed by XRD and Raman shift analysis to verify the structural properties of the ABS crystal. The temperature (300–4.2 K)-dependent resistivity (ρ) shows semiconductor behavior down to 109 K and transforms to metallic behavior down to 19 K. Due to the localization behavior, the resistance shows an upturn up on further decrease in temperature. Charge defects caused by atomic vacancies as well as anti-site defects are thermodynamically induced, and have the potential to shift the Fermi energy level. The two transitions at 109 and 19 K in ρ(T) demonstrate consequent changes as a semiconductor-to-metal transition. The magnetoresistance MR graph exhibits resistive behavior with respect to the magnetic field applied and displays a ‘U’ shape at 300 K, which changes to a ‘V’ shape at 4.2 K. The Hall effect measurements reveal that the majority carrier is a hole. The carrier density as well as mobility changes with respect to temperature are analyzed within the preview of the Ioffe–Regel criterion. ABS is a promising p-type candidate with efficient characteristics that needs further elaboration for thermoelectric, photonic and photovoltaic applications.