Growth Temperature Research Articles

Electric-Field Manipulation of Magnetic Chirality in a Homo-Ferro-Rotational Helimagnet.

Ferro-rotational (FR) materials, renowned for their distinctive material functionalities, present challenges in the growth of homo-FR crystals (i.e., single FR domain). This study explores a cost-effective approach to growing homo-FR helimagnetic RbFe(SO4)2 (RFSO) crystals by lowering the crystal growth temperature below the TFR threshold using the high-pressure hydrothermal method. Through polarized neutron diffraction experiments, it is observed that nearly 86% of RFSO crystals consist of a homo-FR domain. Notably, RFSO displays remarkable stability in the FR phase, with an exceptionally high TFR of ≈573K. Furthermore, RFSO exhibits a chiral helical magnetic structure with switchable ferroelectric polarization below 4K. Importantly, external electric fields can induce a single magnetic domain state and manipulate its magnetic chirality. The findings suggest that the search for new FR magnets with outstanding material properties should consider magnetic sulfates as promising candidates.

Plasma surface treatment of amorphous Ga2O3 thin films for solar-blind ultraviolet photodetectors

Recently, amorphous gallium oxide (a-Ga2O3) thin films are gaining more and more attention due to their advantages of low cost and low temperature growth. However, a-Ga2O3 solar-blind ultraviolet photodetectors are plagued by issues such as slow response speed and high dark current. In this work, radio frequency magnetron sputtering was used for a-Ga2O3 deposition, and a novel approach of plasma treatment (including oxygen, argon and hydrogen plasmas) was employed to tailor the device performance using a plasma-enhanced chemical vapor deposition system. It is demonstrated that: (i) the oxygen atoms and ions in the oxygen plasma effectively reduce the oxygen vacancy concentration and improve the respond speed of a-Ga2O3 photodetectors; (ii) the argon ions in the argon plasma create additional defects (such as dangling bonds and oxygen vacancies) and improve the responsivity of a-Ga2O3 photodetectors; (iii) the hydrogen atoms in the hydrogen plasma may incorporate into the film and form an ultra-thin passivation layer near the surface, which gives rise to a balance between responsivity and response speed. Finally, through the detailed analysis of the optical emission spectra and photoelectric performance, the underlying physical mechanism based on the energy band diagram has been proposed to interpret the obtained experimental results.

Isolation, Characterization and Optimization of Indigenous Petrol Degrading Bacteria from Oil Contaminated Soil

Petroleum-derived products like petrol, containing complex hydrocarbons, have catastrophic environmental effects, posing a universal challenge. Bioremediation is known as eco-friendly and safe technique for removal of hydrocarbon pollutants. In this study, indigenous bacteria were isolated from oil contaminated soils and screened for their biodegradation potential. The bacterial enrichment and isolation were done using selective media Bushnell-Haas supplemented with petrol as a sole carbon source. Out of fifteen isolated strains best two isolates S4P2 and S14P1 were selected on basis of DCPIP screening method. These isolates were identified as Pseudomonas chengduensis & Pseudomonas donghuensis by 16S rRNA gene sequencing. The growth parameters were optimized by one factor at a time. The optimum growth temperature for P.chengduensis & P. donghuensis was found to be 37°C at pH 7 with a substrate concentration of 1%.

Influence of Growth Temperature on Morphological and Structural Properties of Sputtered- Zinc Oxide Nanorods

Zinc oxide is highly sought after for several applications in biology, optoelectronics, electronics, and sensing. Zinc oxide nanorods exhibit a high exciton binding energy and a wide direct band gap, making them an attractive material for ultraviolet optoelectronic devices in the compound semiconductor field. This investigation focuses mainly on the influence of growing temperature on the crystal structure and surface morphology of ZnO nanorods, specifically for their application as UV photodetectors. Si (100) substrates were utilized for the growth of ZnO nanorods using radio frequency magnetron sputtering. The ZnO nanorods are grown at temperatures of 350 °C, 375 °C, and 400 °C, respectively. The crystal structure and surface morphology were examined using X-ray diffraction and scanning electron microscopy. The samples exhibited a same crystal orientation of the (002) diffraction peak at all growth temperatures. The growth temperatures show a direct influence on the density and length of nanorods, as evidenced by the scanning electron microscopy photographs. The results revealed the significant influence of substrate temperature on the regulation of nanorod length and crystal formation.

Pulsed Laser Deposition of Epitaxial SrTiO3/Sr3Al2O6 Templates as a Water-Soluble Sacrificial Layer for GaAs Growth and Lift-Off.

Despite the record-high efficiency of GaAs solar cells, their terrestrial application is limited due to both the particularly high costs related to the required single-crystal substrates and epitaxial growth. A water-soluble lift-off layer could reduce costs by avoiding the need for toxic and dangerous etchants, substrate repolishing, and expensive process steps. Sr3Al2O6 (SAO) is a water-soluble cubic oxide, and SrTiO3 (STO) is a perovskite oxide, where a SAO ≈ 4 × a STO ≈ (2√2)a GaAs. Here, the pulsed laser-deposited epitaxial growth of SrTiO3/Sr3Al2O6 templates on STO and Ge substrates for epitaxial GaAs growth was investigated, where SAO works as a sacrificial layer and STO protects the hygroscopic SAO during substrate transfer between deposition chambers. We identified that the SAO film quality is strongly dependent on the growth temperature and the O2 partial pressure, where either a high T or a high P(O2) improves the quality. XRD spectra of the films with optimized deposition parameters showed an epitaxial STO/SAO stack aligned to the STO (100) substrate, and TEM analysis revealed that the grown films were epitaxially crystalline throughout the thickness. The STO/SAO growth on Ge substrates at a high T with no intentional O2 flow resulted in some nonepitaxial grains and surface pits, likely due to partial Ge oxidation. GaAs was grown by metalorganic vapor-phase epitaxy (MOVPE) on STO/SAO/STO templates. Lift-off after dissolving the sacrificial SAO in water resulted in free-standing ⟨001⟩ preferentially oriented polycrystalline GaAs.

Declining planetary health as a driver of camera-trap studies: Insights from the web of science database

Planetary health is crucial to human well-being, ecosystem sustainability, and biodiversity preservation. In this context, camera traps are an effective remote sensing tool for monitoring biodiversity. Given the rising importance of understanding biodiversity patterns and trends, this study examines possible factors influencing camera-trap studies and provides bibliometric insights from 2377 publications indexed in the Web of Science (WoS). To explore the potential drivers of camera-trap research growth, we used a logistic model based on specific variables, including global gross domestic product, temperature growth, a planetary health measure the declining living planet index, and human population growth. The living planet index was identified as a statistically significant driver of camera-trap research growth (p-value <0.01), suggesting that curiosity regarding other living beings influences studies. Through the bibliometric analysis, we observed that camera-trap studies are predominantly conducted in the United States, followed by England and Australia, with a notable upward trend over recent years. These studies align with sustainable development goal 15 (Life on Land) and are primarily classified under the ecology category in WoS. Further, we have visualized the network of co-occurrence of authors and authors' affilation regions, keywords, and keywords plus documents. Overall, this study assesses ecological and conservation informatics and provides a reference to scholars, policymakers, and decision-makers.

Synthesis of Samarium Nitride Thin Films on Magnesium Oxide (001) Substrates Using Molecular Beam Epitaxy

Rare-earth nitrides are an exciting family of materials with a wide variety of properties desirable for new physics and applications in spintronics and superconducting devices. Among them, samarium nitride is an interesting compound reported to have ferromagnetic behavior coupled with the potential existence of p-wave superconductivity. Synthesis of high-quality thin films is essential in order to manifest these behaviors and understand the impact that vacancies, structural distortions, and doping can have on these properties. In this study, we report the synthesis of samarium nitride monocrystalline thin films on magnesium oxide (001) substrates with a chromium nitride capping layer using molecular beam epitaxy (MBE). We observed a high-quality monocrystalline SmN film with matching orientation to the substrate, then optimized the growth temperature. Despite the initial 2 nm of growth showing formation of a potential samarium oxide layer, the subsequent layers showed high-quality SmN, with semiconducting behavior revealed by an increase in resistivity with decreasing temperature. These promising results highlight the importance of studying diverse heteroepitaxial schemes and open the door for integration of rare-earth nitrides and transition metal nitrides for future spintronic devices.

Kinetics-controlled epitaxial growth and bipolar transport properties of semimetal Bi4Se3

(Bi2)m(Bi2Se3)n (m, n: integers) compounds with an infinitely adaptive superlattice structure exhibit several fascinating topological phases. Here, we study kinetics-controlled epitaxial growth of Bi4Se3 on mica by co-evaporating Bi and Se using molecular beam epitaxy technique, as well as the transport properties of Bi4Se3. By precisely controlling the beam fluxes of Bi and Se and growth temperature, we can tune the growth modes from van der Waals' condensation to spiral growth, thus achieving single-crystalline Bi4Se3 of dislocation-free microplate or mounded thin-film morphologies. This reflects a transition from near-thermodynamic-equilibrium to non-thermodynamic-equilibrium growth processes of single-crystalline Bi4Se3. Thin-film Bi2+xSe3 (1.7 &amp;lt; x &amp;lt; 2) solid-solution phases consisting of randomly stacked Bi2 and Bi2Se3 units are also prepared as comparative samples. Hall and thermopower properties suggest that the as-grown Bi4Se3 films exhibit semimetallic bipolar conduction behaviors while the Bi2+xSe3 films present typical semiconducting transport characteristics with a n-type polarity. Due to semiconductor band structures, the Bi2+xSe3 films show superior thermopower to that of semimetal Bi4Se3.

Electronic Properties of Atomic Layer Deposited HfO2 Thin Films on InGaAs Compared to HfO2/GaAs Semiconductors

This paper demonstrates how the treatment of III-V semiconductor surface affects the number of defects and ensures the conformal growth of the high-k dielectric thin film. We present the electrical properties of an HfO2/InGaAs-based MOS capacitor, in which growth temperatures and surface treatments of the substrate are two key factors that contribute to the uniformity and composition of the HfO2 thin films. A remarkable asymmetry observed in capacitance versus voltage measurements was linked to the interface defects and charge redistribution, as confirmed from X-ray photoelectron spectroscopy. The GaAs substrates that were etched with only NH4OH showed a large frequency dispersion and a higher surface roughness; however, the HfO2 thin films grown on GaAs pre-treated with both NH4OH etching and (NH4)2S passivation steps produced a desirable surface and superior electronic properties.

Low defect density in MoS2 monolayers grown on Au(111) by metal-organic chemical vapor deposition

Monolayers of transition metal dichalcogenides (TMDs) possess high potential for applications in novel electronic and optoelectronic devices and therefore the development of methods for their scalable growth is of high importance. Among different suggested approaches, metal-organic chemical vapor deposition (MOCVD) is the most promising one for technological applications because of its lower growth temperature compared to the most other methods, e.g., conventional chemical vapor or atomic layer deposition (CVD, ALD). Here we demonstrate for the first time the epitaxial growth of MoS2 monolayers on Au(111) by MOCVD at 450 °C. We confirm the high quality of the grown TMD monolayers down to the atomic scale using several complementary methods. These include Raman spectroscopy, non-contact atomic force microscopy (nc-AFM), X-ray photoelectron spectroscopy and scanning tunneling microscopy (STM). The topographic corrugation of the MoS2 monolayer on Au(111), revealed in a moiré structure, was measured as ≈20 pm by nc-AFM. The estimated defect density calculated from STM images of the as-grown MoS2 monolayers is in the order of 1012 vacancies/cm2. The defects are mainly caused by single sulfur vacancies. Our approach is a step forward towards the technologically relevant growth of high-quality, large-area TMD monolayers.

Genomic signatures of cold adaptation in the family Colwelliaceae.

Psychrophily is a phenotype describing microbial growth at low temperatures; elucidating the biomolecular and genomic adaptations necessary for survival in the cold is important for understanding life in extreme environments on Earth and in outer space. We used comparative genomics and temperature growth experiments of bacteria from the family Colwelliaceae to identify genomic factors correlated with optimal growth temperature (OGT). A phylogenomic analysis of 67 public and 39 newly sequenced strains revealed three main clades of Colwelliaceae. Temperature growth experiments revealed significant differences in mean OGT by clade, wherein strains of Colwelliaceae had similar growth rates at -1°C but varied in their ability to tolerate 17°C. Using amino acid compositional indices, a multiple linear regression model was constructed to predict the OGT of these organisms (RMSE 5.2°C). Investigation of Colwelliaceae functional genes revealed a putative cold-adaptive gene cassette that was present in psychrophilic strains but absent in a closely related strain with a significantly higher OGT. This study also presents genomic evidence suggesting that the clade of Colwelliaceae containing Colwellia hornerae should be investigated as a new genus. These contributions offer key insights into the psychrophily phenotype and its underlying genomic foundation in the family Colwelliaceae.

Molecular beam epitaxy growth of topological insulator Bi4Br4 on silicon for the infrared applications

Bi4Br4 is a material rich in intriguing topological properties. Monolayer Bi4Br4 film exhibits helical edge states characteristic of a quantum spin Hall insulator, while bulk Bi4Br4 represents a higher-order topological insulator with hinge states. However, direct exfoliation from single crystal can only obtain thin nanowires due to the weak van der Waals forces between Bi4Br4 chains, which limits its optical analysis and application, while the growth of Bi4Br4 thin films is also full of challenges due to the extremely narrow growth temperature range and the accurate control of the BiBr3 flux. Here, we reported the controlled growth of α-Bi4Br4 thin films on intrinsic silicon substrates using molecular beam epitaxy. The growth temperature, BiBr3 flux, and the flux ratio of Bi and BiBr3 were accurately controlled. Then, the morphology, composition, and bonding of the prepared films were investigated using atomic force microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. The growth of large, uniform thin films provides an ideal material platform for studying the physical properties of Bi4Br4. Additionally, we utilized Fourier-transform infrared spectroscopy to explore the film’s infrared characteristics, revealing strong absorption in the low frequency range due to the high proportion of one-dimensional topological edge states and laying the groundwork for further exploration of its potential applications in the optoelectronic field.

Effects of Ocean Acidification and Temperature Coupling on Photosynthetic Activity and Physiological Properties of Ulva fasciata and Sargassum horneri.

To investigate the ecological impacts of macroalgae in the framework of shifting global CO2 concentrations, we conducted a study utilizing Ulva fasciata and Sargassum horneri specimens sourced from the Ma'an Archipelago in Zhejiang Province on how ocean acidification (OA) and temperature changes interact to affect the photosynthetic physiological responses of macroalgae. The results of the study showed that OA reduced the tolerance of U. fasciata to bright light at 20 °C, resulting in more pronounced photoinhibition, while 15 °C caused significant inhibition of U. fasciata, reducing its growth and photosynthetic activity, but OA alleviated the inhibition and promoted the growth of the alga to a certain extent. The tolerance of S. horneri to bright light was also reduced at 20 °C; the inhibition was relieved at 15 °C, and the OA further improved the algal growth. The Relative Growth Rate (RGR), photosynthetic pigment content, and the release of the dissolved organic carbon (DOC) of U. fasciata were mainly affected by the change in temperature; the growth of the alga and the synthesis of metabolites were more favored by 20 °C. A similar temperature dependence was observed for S. horneri, with faster growth and high metabolism at 15 °C. Our results suggest that OA reduces the tolerance of macroalgae to high light at suitable growth temperatures; however, at unsuitable growth temperatures, OA effectively mitigates this inhibitory effect and promotes algal growth.

Growth of Hg0.7Cd0.3Te on Van Der Waals Mica Substrates via Molecular Beam Epitaxy.

In this paper, we present a study on the direct growth of Hg0.7Cd0.3Te thin films on layered transparent van der Waals mica (001) substrates through weak interface interaction through molecular beam epitaxy. The preferred orientation for growing Hg0.7Cd0.3Te on mica (001) substrates is found to be the (111) orientation due to a better lattice match between the Hg0.7Cd0.3Te layer and the underlying mica substrate. The influence of growth parameters (mainly temperature and Hg flux) on the material quality of epitaxial Hg0.7Cd0.3Te thin films is studied, and the optimal growth temperature and Hg flux are found to be approximately 190 °C and 4.5 × 10-4 Torr as evidenced by higher crystalline quality and better surface morphology. Hg0.7Cd0.3Te thin films (3.5 µm thick) grown under these optimal growth conditions present a full width at half maximum of 345.6 arc sec for the X-ray diffraction rocking curve and a root-mean-square surface roughness of 6 nm. However, a significant number of microtwin defects are observed using cross-sectional transmission electron microscopy, which leads to a relatively high etch pit density (mid-107 cm-2) in the Hg0.7Cd0.3Te thin films. These findings not only facilitate the growth of HgCdTe on mica substrates for fabricating curved IR sensors but also contribute to a better understanding of growth of traditional zinc-blende semiconductors on layered substrates.

Effects of Temperature and Nitrogen Limitation on Growth and Lipid Production of Oleaginous Microalgae from Hot Springs

Oleaginous microalgae have gained increasing attention as an alternative feedstock for biodiesel production due to the increasing demand of fuel, climate change, and global warming. This study aimed to isolate and screen robust microalgal strains from hot springs for cultivation in subtropical and tropical areas. The newly isolated oleaginous microalgae were cultivated at 30, 35 and 40 °C. Among mesophilic and thermophilic strains tested, Chlamydomonas sp. HP59 is considered the most robust strain as it showed high cell growth in a broad range of temperatures (30 - 40 °C), with the maximum dried cell weight at 40 °C. Un-optimal temperatures for cell growth did improve lipid content by 2 - 4 folds. To increase lipid production, the 2-stage cultivation, in which nitrogen-rich was applied to promote cell growth in the 1st stage and nitrogen-limitation was applied to stimulate lipid accumulation in the 2nd stage, was performed. The high temperature combined with nitrogen-limitation did improve lipid production by all microalgae. With this strategy, Chlamydomonas sp. HP59 showed the highest dried cell weight of 4.33 g/L and lipid production of 1.72 g/L. This study has shown the potential use of the newly isolated oleaginous microalgae from hot springs to be cultivated at high temperatures and under nitrogen-limited conditions for the production of biodiesel feedstocks. HIGHLIGHTS Mesophilic and thermophilic oleaginous microalgae were isolated from hot springs. Un-optimal temperatures for cell growth did improve lipid content by 2 - 4 folds. Combined effect of high temperature and nitrogen limitation effectively increased lipid content. Two-stage cultivation gave high dried cell weight and hence overall high lipid production. GRAPHICAL ABSTRACT

Tailoring Ge membrane adhesion strength: Impact of growth parameters and porous layer thickness

The recent exploration of porous Germanium (PGe) techniques marks a significant advancement in the scalable production of detachable Ge membranes and devices. However, there is a notable gap in the comprehensive understanding of the critical factors necessary to control the adhesion strength of these nanomembranes. This study delves into the effects of Ge growth temperature, in-situ annealing processes, and the thickness of the PGe layer on the reorganization of the porous interlayer, subsequently influencing the properties of the separation layer. We particularly focus on how adjusting these parameters can fine-tune the adhesion strength of the epitaxial layer, ranging from a freestanding state to a fully bonded nanomembrane. A key finding is that the thermal budget experienced by the porous structure during the buffer layer's growth significantly affects the nanomembrane's adhesion characteristics; it is imperative to minimize this duration, especially at higher growth temperatures. Our research demonstrates that by precisely controlling the voids within the PGe layer, the adhesion strength can be effectively modulated through variations in the PGe layer's thickness. The outcomes of this study offer crucial insights into the controllable adhesion strength of Ge nanomembranes, paving the way for the targeted development of detachable devices.

Effects of slow temperature acclimation of photosynthesis on gross primary production estimation

The slow temperature acclimation of photosynthesis has been confirmed through early field experiments and studies. However, this effect is difficult to characterize and quantify with some simple and easily accessible indicators. As a result, the impact of slow temperature acclimation of photosynthesis on gross primary production (GPP) estimation has often been overlooked or not integrated into most GPP models. In this study, we used a theorical variable-state of acclimation (S), to characterize the slow temperature acclimation. This variable represents the temperature to which the photosynthetic machinery adapts and is defined as a function of air temperature (Ta) and time constant (τ) required for vegetation to respond to temperature, to discuss its impact on GPP simulation. We used FLUXNET2015 dataset to calculate S and established a GPP model using S and shortwave radiation (SW) based on random forest algorithm (S model). As a comparison, we directly used Ta and SW to build the other GPP model (Ta model). Moreover, the divergent temperature acclimation capacities of plants are crucial to predict and make preparations for likely temperature stress in the future. Therefore, the spatial distribution of τ values was also mapped using satellite sun induced chlorophyll fluorescence (SIF) and Ta datasets. The results indicated that: (1) taking into account the slow temperature acclimation of photosynthesis led to a more precise estimation of GPP which mainly reflected in reduction of excessive fluctuations in GPP predictions; (2) considering the slow temperature acclimation of photosynthesis can reduce the sensitivity of vegetation to temperature; (3) the improvement of S model in GPP estimations was different in different vegetation growth stages which was more significant in the springtime recovery stage; (4) τ values had significant spatial distribution which was strongly affected by the determinants of vegetation growth and seasonal variations in temperature.

Role of electrode temperature in anodic growth of sulfuric acid alumina films

Role of electrode temperature in anodic growth of sulfuric acid alumina films

Powder bed fusion with electron beam: The interplay of sintering, porosity, and coordination number in modelling the powder thermal conductivity through a novel tortuosity formulation

For the powder bed fusion with electron beam (PBF-EB) additive manufacturing, properties such as the thermal conductivity of the material surrounding the melting area are critical. Thermal conductivity is influenced by the extremely high temperature reached in a short time and distributed in the building area. This fast temperature growth produces sintering phenomena and the creation of a neck between the particles. Because of this sintering, measuring the thermal conductivity at the process conditions is challenging.This paper proposes an analytical formulation for estimating the effective powder bed thermal conductivity at the PBF-EB conditions, introducing a novel modelling strategy for the tortuosity factor. In a changing net of sintered powder particles, the proposed model for the tortuosity factor considers the neck evolution and the complexity of the heat transfer due to the several heat paths possible through the particle net. To show the effectiveness of the proposed model, the thermal conductivity is evaluated for three 3D structures characterised by an increasing number of powder particles and heat path complexity: a simple cubic, a body centred cubic and a portion of a powder bed. It is shown that thermal conductivity strongly depends on the arrangement of the particles in 3D space, the structure density and the complexity of the heat diffusion path (tortuosity). Also, the numerical results from the proposed model show good agreement when compared with finite element analysis and experimental literature data.

Comprehensive analysis of targeted phenolic, sugar, and amino acid variation in 10‐day‐old wheatgrass in response to temperature and photoperiod

SummaryThe present study investigated the phenolic profile, sugar composition and amino acid profile of lyophilised 10‐day‐old wheatgrass cultivated under varying temperature and photoperiod conditions. The targeted phenolic profile showed the abundant presence of chlorogenic, caffeic, ferulic and p‐coumaric acid. The phenolic content varied with temperature and photoperiod conditions. The comprehensive sugar profile indicated the variation in the concentration of glucose with different growing conditions altered carbohydrate metabolism in wheatgrass. Similarly, the concentration of amino acids also varied with growing conditions. Notably, the concentration of proline, arginine and GABA in wheatgrass from all wheat varieties increased more prominently in photoperiod of 22 h and growth temperature of 22 °C in light and 17 °C in dark as a response of defence mechanism.