Crystal Research and Technology最新文献

Single-crystal silicon carbide (SiC) is an important semiconductor material for the fabrication of power and radio frequency (RF) devices. The major technique for growing single-crystal SiC is the so-called physical vapor transport (PVT) method, in which not only the thermal field but also the fluid-flow field and the distribution of gas species can be hardly measured directly. In this study, a multi-component flow model is proposed that includes the inside and outside of a growth chamber and a joint between the seed crystal holder and crucible which allows exchanges of the gas species. The joint is simulated as a thin porous graphite sheet. The Hertz-Knudsen equation is used to describe the sublimation and deposition. The convection and diffusion are described by the Navier–Stokes equations and mixture-averaged diffusion model, in which the Stefan flow is taken into account. The numerical simulations are conducted by the finite element method (FEM) with a multi-physics coupled model, which is able to predict the fluid flow field, species distribution field, crystal growth rate, and evolution of the molar concentration of dopant gas. Using this model, the effects of several experimental conditions on the transport of gas species and the growth rate of single-crystal SiC are analyzed.

Indium selenides (InSe) is a promising layer-structured semiconductor with broad potential applications in photovoltaics, diodes, and optic devices, but its thermoelectric performance is limited by the high thermal conductivity. In this work, by alloying high-performance thermoelectric SnSe in InSe, the In_0.5Sn_0.5Se crystal is prepared via a zone melting method. The density of In_0.5Sn_0.5Se crystal is measured as 5.81 g cm⁻³ which is between the density of pure SnSe and InSe. The XRD measurements indicate that the grown In_0.5Sn_0.5Se crystal consists of InSe and SnSe crystals with a preferred orientation along (00l) and (h00) planes, respectively. SEM and EDS analysis reveal that eutectic InSe and SnSe phases interdigitate with each other. The thermogravimetry analysis shows a slow decrease at a temperature ≈700 °C. In_0.5Sn_0.5Se crystal displays a n-type conduct behavior, the electrical conductivity σ is ≈0.02 Scm⁻¹ at room temperature and increases to 8.4 Scm⁻¹ under 820 K. The highest power factor PF is estimated to be ≈0.36 µWcmK⁻² near 570 K. The InSe-SnSe phase boundaries lead the thermal conductivity of In_0.5Sn_0.5Se crystal to be as low as 0.29 Wm⁻¹K⁻¹. Due to the low lattice thermal conductivity, In_0.5Sn_0.5Se crystal shows a ZT value of 0.04 at 600 K in this work.

In this study, phosphogypsum (PG) is simulated by doping fluorine and phosphorus ions in an analytically pure reagent of gypsum dihydrate. The influence of fluorine and phosphorus impurity and content on the dehydration reaction process of phosphogypsum and its crystalline micromorphology is assessed during the preparation of α-type gypsum hemihydrate in the reversed-phase microemulsion system and its mechanism. The results show that when the fluorine content increases from 0 to 1.0 mol L⁻¹ (ωNaF = 1.0 mol L⁻¹), the dehydration process of dihydrate gypsum will be greatly slowed down. Scanning electron microscopy (SEM) analysis showed that even a small amount of F− (ωNaF = 0.2 mol L⁻¹) can significantly inhibit the formation of α-type hemi-hydrated gypsum. When ωH₃PO₄ = 0.10 mol L⁻¹, the water of crystallization content in the solid phase of the sample decreased to 5.24% after 90 min, which is significantly lower than during the same period of the benchmark group. However, there is a threshold value for the effect of phosphorus on the microscopic morphology of the α-type gypsum hemihydrate crystals, when ωH₃PO₄ ≤ 0.04 mol L⁻¹, the crystal morphology is basically unaffected. Moreover, when ωH₃PO₄ continued to increase, the defects on the crystal surface increased.

Due to the ecocompatibility with carbonate-based substrates, Ca(OH)₂ nanoparticles are currently used for cultural heritage conservation such as wall paintings. However, the nano Ca(OH)₂ still suffers from different forms and poor uniformity, limiting its application potential. Also, there is a lack of systematic comparative studies between nano Ca(OH)₂ and the commonly used wall painting reinforcement materials. In this study, homogeneous hexagonal nano Ca(OH)₂ particles with a size of ≈100 nm are successfully prepared through the convenient chemical liquid phase method and by utilizing surfactants to control the growth. The resulting nano Ca(OH)₂ is less agglomerated and has superior crystalline morphology, prolonged suspension time, and more suitable carbonation time in comparison to commercial Ca(OH)₂ materials. Additionally, the reinforcement effect of the resulting nano-Ca(OH)₂ with that of the commonly used pigment layer reinforcement materials such as AC33, B72, Tetraethyl orthosilicate, WPU (Waterborne polyurethane) and commercial Ca(OH)₂ is systematically compared. The synthesized nano Ca(OH)₂ penetrated wall painting blocks to a depth of 683 µm, three times deeper than commercial Ca(OH)₂, achieving moderate color deviation, higher flexural strength (0.529 MPa), and bond strength (1.105 mg cm⁻²), thus highlighting its potential in wall painting reinforcement and expanding its application scope.

Cover image provided courtesy of Jianguang Zhou, Research Center for Analytical Instrumentation, Institute of Cyber-Systems and Control, State Key Laboratory of Industrial Control Technology, Zhejiang University, China.

This research presents the successful synthesis of Cu_0.79Co_0.21La_xFe_2-xO₄ (0.0 ≤ x ≤ 0.8) (spinel ferrite) nanoparticles via the sol-gel auto combustion technique, with varying La³⁺ dopant concentrations. In this study, the estimated crystallite size (D) is found to be in the range of (27.92–40.90) nm. The microstructural parameter determination in XRD data is improved using Rietveld refinement. Fourier Transform Infrared Spectroscopy (FTIR) spectra exhibit two distinct metal stretching vibrational bands within (400–600) cm⁻¹ range, a characteristic fingerprint region for all ferrites. Field Emission Scanning Electron Microscopy (FESEM) analysis reveals the agglomeration of particles due to magnetic interactions and non-uniform distribution of average particle sizes ranging from (1.06–1.87) µm. Energy Dispersive X-Ray Analysis (EDX) validates the chemical composition's accuracy. Owing to the dilution effect resulting from the introduction of non-magnetic La³⁺ ions into the ferrite structure, there is a reduction in the saturation magnetization value, decreasing from 37.28 to 6.24 emu g⁻¹ in the Vibrating Sample Magnetometery (VSM) study. The electrochemical analysis reveals the impressive electrochemical characteristics of the newly developed ferrites, highlighting a remarkable specific capacitance of 270.0 F g⁻¹. This finding positions them as highly promising contenders for a wide range of energy storage supercapacitor applications.

I am very glad to share that our SSN Research Centre, Department of Physics, and SSN Institutions in association with the International Organization for Crystal Growth and Indian Association for Crystal Growth had organized the 3rd International Symposium on “Modeling of Crystal Growth Processes and Devices (MCGPD-2023)” during March 06–08, 2023. The 3 days international symposium was highly propitious for the researchers who are working in the field of modeling and simulation of various crystal growth processes, semiconductor devices, NLO, and piezoelectric devices. The goal of the symposium was to give a fundamental understanding of modeling prospects to young researchers in exploring recent and advanced developments. The symposium included 31 Plenary/Keynote/Invited lectures by eminent experts from foreign and Indian institutions. Around 230 posters/oral presentations from the researchers were presented. Professors/Scientists from leading crystal growth countries like the USA, Israel, Japan, Germany, France, Russia, Romania, and Taiwan participated and presented their work in the symposium. In our country, Professors/Scientists, and young researchers from various leading institutes like IITs, IISc, CSIR labs, Central and state universities, and colleges took active participation.

The 3 days symposium was conducted in 12 technical sessions, which were constituted of 25 Keynote lectures, 6 Plenary talks, and 230 post/oral presentations. The symposium started with a welcome address by Prof. P. Ramasamy, President of the Indian Association for Crystal Growth, following that Prof. Umesh V Wgahmare, President, IASc, Banglore, and Prof. Noritaka Usami, Nagoya University, Japan gave Chief Guest addresses. The symposium was inaugurated with the release of the MCGPD-2023 abstract book by Prof. Koichi Kakimoto, President of the International Organization for Crystal Growth, and felicitated by Prof. Kozo Fujiwara, Tohoku University, Japan, and Prof. Jyh-Chen Chen, Vice-President, National Central University Taiwan, etc.,

The main motive of the 2nd Indo-Japan Joint Workshop on Photovoltaics (IJWP-2023) workshop was to bring together eminent researchers from India and Japan to share their ideas and recent developments in the field of photovoltaic technologies. Around 70 abstracts have been submitted to IJWP-2023, of which only high-quality papers are accepted to be presented as posters in this event. The chief highlights of this workshop are the 13 talks delivered by distinguished scientists like Prof. Noritaka Usami, Nagoya University, Prof. Yoshitaka Okada, RCAST, The University of Tokyo, Dr.Kosuke O. Hara, University of Yamanashi, Dr. Kentaro Kutsukake, RIKEN, Nagoya University, Dr.Yutaka Ohno, Tohoku University, Dr.P.Ramasamy, SSN Institutions, Dr. Anil Kottantharayil IIT Bombay, Dr. J. K. Bath IIT Madras, Dr. Vamsi Krishna IIT Delhi, Dr. C.V Kannan, Adani Solar, Dr. Sanjay K. Srivastava NPL, Dr S Sudhakar, CSIR-CEERI, Dr.Ka

Recovering manganese from waste batteries is an important issue to promote the development of new energy. Herein, nickel sulfate and cobalt sulfate, representative impurities in waste battery leachate, are selected to examine their influence on the crystallization thermodynamics and crystal nucleation of manganese sulfate monohydrate. This work assessed alterations in solubility and metastable zone width (MSZW) due to the presence of impurities. The results showed a decrease in manganese sulfate monohydrate solubility in water with increasing impurity concentrations of either nickel sulfate or cobalt sulfate. The effects of initial concentration, heating rate, and impurity concentration on MSZW demonstrated a consistent increase in MSZW as these factors increased. The MSZW data are fitted using the self-consistent Nývlt-like model and the classical 3D nucleation theory model. The results revealed a general increase in the nucleation rate constant, K, with increasing saturation temperature or decreasing nickel sulfate concentration. Conversely, the solid-liquid interface energy, γ, generally decreases with increasing saturation temperature or decreasing nickel sulfate concentration. Based on the influence observed on the interface energy, a possible mechanism is proposed that suggests that impurities inhibit crystal nucleation through adsorption.

Herein transparent iron nanosheets deposited by the ionic coating technique onto glass and WO₃ dielectric lenses are studied and characterized. The thickness of Fe nanosheets is varied in the range of 70–350 nm. It is observed that the transmittance and reflectance of the Fe nanosheets are highly affected by the layer roughness. Coating of iron nanosheets onto WO₃ dielectric lenses increases the light absorption of WO₃ by more than 240 times and red-shifts the energy bandgap. Remarkable enhancements in the dielectric constant and in the optical conductivity are achieved via Fe coatings. In addition, iron coated dielectric lenses show higher terahertz cutoff limits varying in the range of 1.0–30 THz. Iron nanosheets remarkably increase the free charge carrier density and plasmon frequency in the infrared range of light. Moreover, the temperature dependent electrical conductivity shows high temperature stability and an increased electrical conductivity by more than 7 orders of magnitude by coating WO₃ with 70 nm thick Fe nanosheets. The stability of the electrical conductivity at low temperatures and the wide range of terahertz cutoff limits in addition to the well-enhanced light absorbability makes the iron coated tungsten oxide dielectric lenses promising for multifunction optoelectronic applications.