Single Substrate Research Articles

Planar dual-band bandpass filter with regular harmonic suppression

Abstract This paper presents a dual-band bandpass filter with regular harmonic suppression. The proposed third-order filter consists of two microstrip stepped impedance resonators and single substrate integrated waveguide resonator. The mismatches in their higher order resonant frequencies are utilized to suppress the regular harmonics. The passbands are centered at f1 = 2.4 GHz and f2 = 3.5 GHz with fractional bandwidths of 5% and 7.5%, respectively. The measured midband insertion and return losses are better than 2.55 and 14.5 dB for the first, whereas for the second band, they are better than 1.95 and 14 dB. The filter offers at least 33 dB suppression of first three higher order regular harmonics of f1 and f2.

Preparation of double-layer REBa2Cu3O7−δ tapes for enhancing engineering current density by Ag-diffusion bonding

Second-generation high-temperature superconducting (2G-HTS) tapes with high engineering critical current densities (Je) are widely used in engineering and technology applications. This study introduced a twisting device that successfully layered two REBa2Cu3O7−δ films onto a single substrate. Heating the twisting device to above 600 °C induced Ag-diffusion bonding at the interface between the two tapes. A thin film pressure sensor detected a silver layer pressure of about 6.5 MPa. After the oxygen annealing treatment, a current increase of 81.7 A was observed using the four-probe method, which was a 1.5-fold enhancement over the original tape current, and the Je was increased from 560 A/mm2 to 790 A/mm2 at 77 K. The use of reverse bending annealing effectively improved the flexibility of the DHOS conductors. Through microanalysis, it was observed that the bonding between MgO and Y2O3 in the buffer layer was weak, resulting in the detachment of LaMnO3 and MgO together with the superconducting layer. The exfoliated buffer layer prevented oxygen penetration, adversely affecting the performance of the double HTS layers on one substrate (DHOS). Moreover, the coverage of the buffer layer increases with the number of layers complicating the complete peeling of the superconducting layer. Further detailed studies point out the direction of improvement for future work in preparing multilayer conductors.

Epitaxial Thin Film Growth on Recycled SrTiO3 Substrates Toward Sustainable Processing of Complex Oxides.

Complex oxide thin films cover a range of physical properties and multifunctionalities that are critical for logic, memory, and optical devices. Typically, the high-quality epitaxial growth of these complex oxide thin films requires single crystalline oxide substrates such as SrTiO3 (STO), MgO, LaAlO3, a-Al2O3, and many others. Recent successes in transferring these complex oxides as free-standing films not only offer great opportunities in integrating complex oxides on other devices, but also present enormous opportunities in recycling the deposited substrates after transfer for cost-effective and sustainable processing of complex oxide thin films. In this work, the surface modification effects introduced on the recycled STO are investigated, and their impacts on the microstructure and properties of subsequently grown epitaxial oxide thin films are assessed and compared with those grown on the pristine substrates. Detailed analyses using high-resolution scanning transmission electron microscopy and geometric phase analysis demonstrate distinct strain states on the surfaces of the recycled STO versus the pristine substrates, suggesting a pre-strain state in the recycled STO substrates due to the previous deposition layer. These findings offer opportunities in growing highly mismatched oxide films on the recycled STO substrates with enhanced physical properties. Specifically, yttrium iron garnet (Y3Fe5O12) films grown on recycled STO present different ferromagnetic responses compared to that on the pristine substrates, underscoring the effects of surface modification. The study demonstrates the feasibility of reuse and redeposition using recycled substrates. Via careful handling and preparation, high-quality epitaxial thin films can be grown on recycled substrates with comparable or even better structural and physical properties toward sustainable process of complex oxide devices.

Superconducting (Ba,K)Fe2As2 epitaxial films on single and bicrystal SrTiO3 substrates

The realization of single crystal and bicrystal films of superconducting materials is of great interest because they allow the investigation of the intragrain performance as well as the understanding of potential limitations in the grain boundary transparency. For many years, the realization of a high-quality (Ba,K)Fe2As2 film has been challenging. Here, the realization of (Ba,K)Fe2As2 epitaxial thin films on single crystal SrTiO3(001) and [001]-tilt-type SrTiO3 bicrystal substrates with high superconducting properties is demonstrated. The epitaxial growth of (Ba,K)Fe2As2 was enabled by implementing an undoped BaFe2As2 buffer layer between the SrTiO3 substrate and (Ba,K)Fe2As2 film. The film exhibits a high Tc of 38.0 K and an extremely high Jc of 14.3 MA/cm2 at 4.2 K. Artificial grain boundaries of (Ba,K)Fe2As2 were also successfully achieved on bicrystals with misorientation angles up to 36.8° by the same preparation methods. The artificial grain boundaries exhibited an identical Tc of 38.0 K and an excellent transfer of the grain orientation from the bicrystal substrates with high crystallinity comparable to that of the high-quality Ba(Fe,Co)2As2 films. This enables the investigation of the intrinsic (Ba,K)Fe2As2 grain boundary nature, which will clarify its potential for superconducting applications, like Josephson junctions, wires, and magnets.

RGB-Single-Chip OLEDs for High-Speed Visible-Light Communication by Wavelength-Division Multiplexing.

Organic light-emitting diodes (OLEDs) have been developed for high-speed transmitters of visible-light communication (VLC) but so far the possibility of direct fabrication of multiple colors on a single substrate has not been exploited for multi-Gbps data transmission. Very fast red-, green-, and blue (RGB)-emitting OLEDs are developed on a single substrate to realize high data transmission speed by wavelength division multiplexing (WDM). -6dB electrical bandwidth of over 100MHz is achieved for all colors by selecting fluorescent materials with nanosecond emission lifetimes and little overlap between their emission spectra and incorporating them into OLEDs designed for high-speed operation. Optical microcavities in top-emitting OLED structures are used to minimize spectral overlap. A record data transmission rate for an OLED transmitter system of 3.2Gbps is demonstrated, by transmitting data with the 3 colors simultaneously and separating each data by dichroic mirrors. The results show that WDM with integrated RGB pixels is a useful way to increase the data transmission rate of a VLC system based on OLED transmitters, which has the potential to enable multi-gigabit transmission by displays. The availability of high-speed multiple-color devices as developed here also expands applications of OLEDs for spectroscopy, sensing, and ranging.

An easy and sensitive assay for acetohydroxyacid synthases based on the simultaneous detection of substrates and products in a single step.

Acetohydroxyacid synthase (AHAS, EC 2.2.1.6) catalyzes the first step in the synthesis of the branched-chain amino acids valine, leucine, and isoleucine, pathways being present in plants and microorganisms, but not in animals. Thus, AHAS is an important target for numerous herbicides and, more recently, for the development of antimicrobial agents. The need to develop new and optimized herbicides and pharmaceuticals requires a detailed understanding of the biochemistry of AHAS. AHAS transfers an activated two-carbon moiety derived from pyruvate to either pyruvate or 2-oxobutyrate as acceptor substrates, forming 2-acetolactate or 2-acetohydroxy-2-butyrate, respectively. Various methods have been described in the literature to biochemically characterize AHAS with respect to substrate preferences, substrate specificity, or kinetic parameters. However, the simultaneous detection and quantification of substrates and unstable products of the AHAS-catalyzed reaction have always been a challenge. Using AHAS isoform II from Escherichia coli, we have developed a sensitive assay for AHAS-catalyzed reactions that uses derivatization with ethyl chloroformate to stabilize and volatilize all reactants in the aqueous solution and detect them by gas chromatography coupled to flame ionization detection or mass spectrometry. This assay allows us to characterize the product formation in reactions in single and dual substrate reactions and the substrate specificity of AHAS, and to reinterpret previous biochemical observations. This assay is not limited to the AHAS-catalyzed reactions, but should be applicable to studies of many metabolic pathways.

Comprehensive study of epitaxial (Nd,Eu,Gd)Ba2Cu3O7−δ films grown on textured templates

We report the successful epitaxial growth and comprehensive study of structural and superconducting properties of (Nd,Eu,Gd)Ba2Cu3O7−δ films with a thickness of up to 1.2 μm prepared by on-axis pulsed laser deposition on SrTiO3 (STO) single crystals as well as on ion-beam-assisted deposition (IBAD) and rolling-assisted biaxially textured substrate (RABiTS)-based metal templates. X-ray diffraction demonstrates the epitaxial quality of the grown films on both single crystalline substrates and metal-based templates. In addition, no significant changes in surface morphology were found with increasing thickness for films on all types of substrates. On all substrates, a T c value of about 89 K was observed, however, significant inhomogeneities indicating small superconducting volume were found for all films on STO. In general, the best transport characteristics over a wide range of magnetic fields and temperatures were observed for thicker films on IBAD-MgO and RABiTS templates, respectively. The J c values at 77 K for the films on IBAD-MgO templates are comparable to YBCO films, but inferior in the low temperature region and high magnetic fields, whereas the films on RABiTS and especially on STO showed much lower J c over the entire temperature and magnetic field range. A maximum pinning force of about 7 GN·m−3 at 65 K was found for the 900 nm thick films on IBAD-MgO template. In addition, the pinning mechanism seems to depend on both temperature and type of substrate. In general, no correlation between local microstructure and transport characteristics was revealed for NEG films on both metal templates.

A single-feed circularly polarized antenna with a low vertical profile and hemispherical axial-ratio beam coverage

ABSTRACT A novel wide axial-ratio beamwidth (ARBW) circularly polarized (CP) antenna with a single layer substrate fed by a single probe is proposed. It consists of an inner annular slotted radiator containing eight outer sector units with arc branches, a ground plane, and eight grounded vias. The antenna has an ARBW covering the upper hemisphere and has a low vertical profile. The ultra-hemispherical ARBW is formed by ingeniously merging the endfire omnidirectional CP radiation pattern with the boresight CP radiation pattern. The two radiation patterns can be excited by a central coaxial probe without an additional feeding network. An antenna prototype of dimensions 1.15 × 1.15 × 0.02 (λ 0 3) is fabricated and measured to validate the design concept. Measured results show that the impedance bandwidth of the proposed antenna is 2.0% (3.328–3.394 GHz) and the 3 dB axial ratio (AR) bandwidth is 1.3% (3.332–3.374 GHz). The 3 dB AR beamwidth can cover more than 217° and the maximum gain is 0.79 dBic at 3.35 GHz. A good agreement between the simulated and measured results is obtained.

Life cycle assessment (LCA) and economic analysis of two-stage anaerobic process of co-digesting palm oil mill effluent (POME) with concentrated latex wastewater (CLW) for biogas production

This study outlines the results of a process-based life cycle assessment (LCA) of the environmental performance of biogas production from co-digestion of palm oil mill effluent (POME) and concentrated latex wastewater (CLW) in the two-stage anaerobic digestion (AD) process. Biogas is utilized global across several sectors, including electricity generation, heating, and transportation. The Open LCA 2.0.2 software was used to evaluate the LCA at the midpoint level by using 18 different impact categories. This study reveals the three main contributions of the AD process, which were global warming (8.65 × 102 kg CO2eq), water consumption (5.32 m3), and land use change (3.39 × 102 m2 a crop eq), this result corresponded with the previous study in Malaysia that examined biogas production from the AD of POME In addition, alternative scenarios, in which a single substrate, have been established to quantify the impacts of potential improvements of biogas production to compare with base scenario of co-digestion. The results show that the environmental impacts of the base scenario released were lower than those of the single POME substrate of alternative scenario 1 in most impact categories. Furthermore, economic analysis is a crucial factor in the practical implementation of the AD process. Linking LCA with economic analysis offers a comprehensive perspective on sustainability, balancing environmental impacts with financial performance to optimize the potential of the AD co-digestion process. This is the first study to apply LCA and economic analysis to this specific co-digestion process in a two-stage AD system. The economic analysis of the two-stage AD of co-digesting POME and CLW was 1200 m3/d production of wastewater (70 % of POME and 30 % of CLW) based on the factories' data. The result indicates net present value, internal rate of return, and payback period of 515,813.94 USD, 9.13 %, and 8.87 years, respectively. This work proposed the potential approach for implementing the two-stage AD co-digestion of POME and CLW while concurrently producing valuable bioenergy carriers.

Low-Reynolds-number droplet motion in shear flow micro-confined by a rough substrate

A three-dimensional spectral boundary element method has been employed to compute for the dynamics of the droplet motion driven by shear flow near a single solid substrate with a rough surface. The droplet size is comparable with the surface features of the substrate. This is a problem that has barely been explored but with applications in biomedical research and heat management. This work numerically investigated the influences of surface roughness features, such as the roughness amplitude and wavelength, on the droplet deformation and velocities. We observe that a greater amplitude or wavelength leads to larger variations in droplet velocity perpendicular to the substrate. The droplet velocity along the substrate increases when the amplitude is reduced or when the wavelength increases. The effects of capillary number and viscosity ratios have also been studied. The droplet deformation and its velocity increases as we increase the capillary number, while the viscosity ratio shows a non-monotonic influence on the droplet behavior. The predicted droplet behaviors, including deformation, velocities, and trajectories, can provide physical insight, help to understand the droplet behavior in microfluidic devices without a perfectly smooth surface, and contribute in the design and operation of those devices.

Revisiting the catalytic activity of single horseradish peroxidase clusters through electrochemical collision technique: Effect of electrolyte and substrate

Horseradish peroxidase (HRP) is a versatile biosensing label and signal reporter owing to its broad-spectrum catalytic ability. In present work, we characterized HRP's catalytic performance with various substrates using electrochemical collision technique and analyzed the associated electron transfer processes. Different electrolyte solutions greatly affected enzyme dispersibility and zeta potential, thereby impacting HRP collision dynamics in single H2O2 substrate system. The maximum turnover number (kcat) for single HRP molecules was calculated to be 3.611 ± 0.149 × 103 s−1 in 0.85 % NaCl and 2.967 ± 0.286 × 103 s−1 in 0.1 M PBS solution, reflecting differences in cluster size induced by the electrolyte conditions. More severe agglomeration of HRP molecules was observed in double-substrate systems, where the hydrophilic mediator (K4Fe(CN)6) and lipophilic mediator (ABTS) served as electron donors and signal reporters. The calculated kcat value of single HRP molecules in ABTS-H2O2 was 7.6 times higher than that in K4Fe(CN)6–H2O2. This difference is attributed to mediators' solubility, lipophilicity, and HRP's affinity for different substrates, with HRP demonstrated stronger affinity for ABTS-H2O2 substrates, which realized more efficient electron transfer and compensated for the low diffusion coefficient of ABTS. This work provides a comprehensive analysis of the effects of electrolytes and substrates on HRP collision and catalytic behavior, offering valuable insights for the advanced design of HRP-based biosensors and diagnostic platforms.

Холистическая антропология А.Л. Чижевского в контексте научного и религиозного мировоззрения

The article is devoted to the holistic views of A.L. Chizhevsky on human; fea­tures of their reflection in the philosophical and scientific works of the thinker, as well as in his poetry, are revealed; scientific and religious aspects of the scien­tist’s holistic anthropology are investigated. Analysis of the holistic world­view presented in the metaphysical work “The main beginning of the universe. Cosmic system. Problems”, allows us to state that the holistic approach to the human by Chizhevsky the philosopher is based on his conviction in the impact of the uni­versal principle of circulation on a single electric substrate. A study of the scien­tific works of one of the founders of space natural science suggests that the holistic anthropology reflected in them is based on specific laws that demonstrate human dependence on the environment (solar activity and ionized air). The Chizhevsky-poet forms the reader’s idea of the closest connection between micro- and macrocosm, about the cosmicity of a human being by using vivid images, with­out references to determinism; nevertheless, the anthropocosmic poems of “Leo­nardo da Vinci of the 20th century” are thematically related to his scientific re­search. The relevance of A.L. Chizhevsky’s holistic anthropology to the concept of global evolutionism and the post-classical type of scientific rationality is shown

Research progress in the biosynthesis of xylitol: feedstock evolution from xylose to glucose.

Xylitol, as an important food additive and fine chemical, has a wide range of applications, including food, medicine, chemical, and feed. This review paper focuses on the research progress of xylitol biosynthesis, from overcoming the limitations of traditional chemical hydrogenation and xylose bioconversion, to the full biosynthesis of xylitol production using green and non-polluting glucose as substrate. In the review, the molecular strategies of wild strains to increase xylitol yield, as well as the optimization strategies and metabolic reconfiguration during xylitol biosynthesis are discussed. Subsequently, on the basis of existing studies, the paper further discusses the current status of research and future perspectives of xylitol production using glucose as a single substrate. The evolution of raw materials from xylose-based five-carbon sugars to glucose is not only cost-saving, but also safe and environmentally friendly, which brings new opportunities for the green industrial chain of xylitol.

Integrating use of sugarcane bagasse with sugarcane juice for efficient l-lactic acid production through fed-batch simultaneous saccharification and fermentation: Process configurations and kinetic analysis

The present study investigated the utilization of sugarcane juice (SJ) and sugarcane bagasse (SB) for L-lactic acid (L-LA) production by a newly isolated Enterococcus gallinarum TSKKU D-6. SJ was first investigated as a single substrate, yielding 43.9 ± 2.9 g-LA/L, with a fermentation efficiency of 72.0 ± 0.1 %, based on sucrose content in SJ. On the other hand, simultaneous saccharification and fermentation (SSF) of SB as a single substrate yielded 68.2 ± 2.7 g-LA/L, with a fermentation efficiency of 74.1 ± 0.0 %, based on cellulose content in SB. SSF of SJ and SB as co-substrates was subsequently carried out to increase the acid production, where SJ was first fermented, followed by the addition of SB to enhance LA titer. Effects of mixing and SB addition strategy on the kinetics and economic feasibility of L-LA production were investigated using a bioreactor equipped with a single and dual impellers, as well as the use of dual impellers under fed-batch SSF. The use of single and dual impellers gave similar L-LA titers of 95.9 ± 1.4 and 102.6 ± 0.6 g/L, respectively. Nevertheless, the use of dual impellers shortened the processing time, enhancing LA productivity from 0.37 to 1.12 g/(L·h). As a result, the economic yield and productivity were improved by 7.1 % and 187.5 %, respectively. Better still, performing fed-batch SSF with the use of dual impellers further improved the economic productivity by 8.7 %. This study demonstrated that integrating use of SB as a low-cost substrate considerably enhanced the acid production and lessened the use of SJ. It was also demonstrated that mixing, and process configuration are critical factors determining the process performance.

Combinatorial Optimization of Metal‐Insulator‐Insulator‐Metal (MIIM) Diodes With Thickness‐Gradient Films via Spatial Atomic Layer Deposition

AbstractMetal‐insulator‐insulator‐metal (MIIM) diodes with thickness‐gradient films for the insulator layers are fabricated for the first time. Spatially varying atmospheric‐pressure chemical vapor deposition is used to deposit ZnO and Al2O3 films with orthogonal gradient directions, producing 414 MIIM diodes with 414 different ZnO/Al2O3 film‐thickness combinations on a single substrate for combinatorial and high‐throughput optimization. The nm‐scale ZnO/Al2O3 films are printed in only 2 min and the entire device fabrication takes 7 h, which is much less than conventional approaches for investigating many insulator‐thickness combinations. Rapid identification of the optimal thickness combination is demonstrated; high‐performance diodes (asymmetry = 227, nonlinearity = 13.1, and responsivity = 12 A/W) are observed when a trap‐assisted tunneling mechanism is dominant for insulator thicknesses of 3.4–4.4 nm (ZnO) and 7.4 nm (Al2O3).

Study of cell migration trajectory on two-dimensional continuous stiffness gradient surface edited by grayscale photopolymerization

In native tissues, cells encounter a diverse range of stiffness, which can significantly affect their behavior and function. The ability of cells to sense and respond to these mechanical cues is essential for various physiological processes, including cell migration. Cell migration is a complex process influenced by multiple factors, with substrate stiffness emerging as a critical determinant. This study developed a technique to edit the stiffness of polyacrylamide (PAA) hydrogel substrates by adjusting the grayscale level of a photomask during photopolymerization. By analyzing cell morphologies on the hydrogel, we confirmed the development of a single PAA hydrogel substrate with continuous stiffness gradients. This method was used to explore the correlation between substrate stiffness and cell migration dynamics. The study found that cells typically migrated from softer to stiffer surfaces. When the cells initially located on stiffer surfaces, they were able to travel longer distances. Additionally, a continuous 2D stiffness gradient surface was fabricated to explore how cells migrate on smoother versus steeper stiffness gradients. The results showed that cells tended to migrate more readily on smoother stiffness gradient surfaces compared to steeper ones. This study provides valuable insights into cell migration dynamics on substrates with varying stiffness gradients. The results underscore the importance of the mechanical environment in cancer cell migration and offer promising directions for developing interventions to prevent cancer spread.

Hybrid substrate-based pH autobuffering GABA fermentation by Levilactobacillus brevis CD0817.

The probiotic fermentation of the bioactive substance gamma-aminobutyric acid (GABA) is an attractive research topic. There is still room for further improvement in reported GABA fermentation methods based on a single substrate (L-glutamic acid or L-monosodium glutamate). Here, we devised a pH auto-buffering strategy to facilitate the fermentation of GABA by Levilactobacillus brevis CD0817. This strategy features a mixture of neutral monosodium L-glutamate plus acidic L-glutamic acid as the substrate. This mixture provides a mild initial pH; moreover, the newly dissolved L-glutamic acid automatically offsets the pH increase caused by substrate decarboxylation, maintaining the acidity essential for GABA fermentation. In this study, a flask trial was first performed to optimize the GABA fermentation parameters of Levilactobacillus brevis CD0817. The optimized parameters were further validated in a 10L fermenter. The flask trial results revealed that the appropriate fermentation medium was composed of powdery L-glutamic acid (750g/L), monosodium L-glutamate (34g/L [0.2mol/L]), glucose (5g/L), yeast extract (35g/L), MnSO4·H2O (50mg/L [0.3mmol/L]), and Tween 80 (1.0g/L). The appropriate fermentation temperature was 30°C. The fermenter trial results revealed that GABA was slowly synthesized from 0-4h, rapidly synthesized until 32h, and finally reached 353.1 ± 8.3g/L at 48h, with the pH increasing from the initial value of 4.56 to the ultimate value of 6.10. The proposed pH auto-buffering strategy may be popular for other GABA fermentations.

Vertical Green Wall Systems for Rainwater and Sewage Treatment

Rainwater and sewage are important pollution sources for surface water bodies. Vertical greening systems (VGSs) are extensively employed for these wastewater treatments due to the green and sustainable characteristics, as well as their high-efficiency in pollutant (organic matter, nitrogen, and phosphorus) removal. At present, more and more VGSs are designed with green buildings, serving city ecosystems. This study provides an overview of different kinds of VGSs for rain and sewage treatment, emphasizing their types, design, mechanisms, selection of plants, and growth substrate. Plants play a crucial role in pollutant removal, and different plants usually obtain different efficiencies of water treatment. Climbing plants and ornamental plants with fast growth rates are priority selections for VGSs, including Canna lilies, Jasmine, Grape vine, Boston ivy, Pittosporum tobira, Pelargonium australe, Mentha aquatica, and Lythrum salicaria. The substrate is the most critical part of the VGS, which plays an important role in regulating water flow, supporting plant growth, promoting biofilm growth, filtering pollutants, and adsorbing nutrients. The single substrate either has a blockage problem or has a short holding time. Therefore, a number of studies have mixed the substrates and integrated the advantages of the substrates to form a complementary effect, thereby improving the overall purification efficiency and stability. Novel substrates (sand, spent coffee grounds, date seeds, coffee grinds, reed-based, etc.) are usually mixed with coco coir, light-weight expanded clay, growstone, or perlite at a certain ratio to obtain optimum treatment performance. Moreover, plants in clay show more significant growth advantages and health statuses than in zeolite or soil. Operating parameters are also significant influences on the treatment performance. This review provides theoretical and technical support for designing sustainable, environmentally friendly, and cost-effective VGSs in treating rainwater and sewage.

Oxygen-close-packed (310)-plane substrates of β-Ga2O3 grown by the casting method

The highly anisotropic crystal structure of β-Ga2O3 gives rise to a variety of crystal planes, among which the (310) plane is a potentially stable close-packed plane for the O sublattice. In this paper, we report the β-Ga2O3 single crystal and substrates with a (310) major plane grown by the spontaneous nucleation technique in the casting method. High-quality crystal growth and substrate processing were confirmed by the 25.67 arc sec full width at half maximum and the 0.25 nm surface roughness. The nanoindentation experiments revealed the (310) substrate's better elastic recovery than that of (100) substrate. The Young's modulus and hardness of (310) substrates were 200 and 7.6 GPa, respectively. The surface barrier height and the Schottky barrier height were 1.25 and 0.92 eV, respectively. First principles calculations identified the (310)-Ga-I plane as the most stable surface configuration of the (310) plane under oxygen-poor condition, with a surface energy density of 1.48 J/m2. The (310) twin boundary formation around the O sublattice has a high energy density of 0.55 J/m2, suggesting its unlikelihood of spontaneous formation. These properties of (310) plane facilitate a high-quality crystal processing and epitaxial growth, thus endowing potential applications in high-quality power devices. Furthermore, the growth and fabrication of the (310) plane provide a route toward understanding the properties of β-Ga2O3 and advancing the growth techniques of oxide crystals.

Substrate orientation influence on nanotwinning in magnetron sputtered CoCrFeMnNi and Ni coatings

This study reveals the influence of crystal orientation on formation of growth twins in magnetron-sputtered coatings. A comparison between materials with low and high stacking fault energy (SFE) was made: CoCrFeMnNi (25 mJ/m2) and Ni (125 mJ/m2). The coatings were grown on a polycrystalline 316L stainless-steel substrate with near-random crystal texture, providing a comprehensive selection of samples on a single substrate. Electron backscatter diffraction was used to identify the film orientation, followed by transmission electron microscopy of selected regions.The presence and density of twins depended on both the material and the growth orientation. For Ni, nanotwins were observed on < 5 % of the substrate grains, on growth directions closest to 〈111〉 . All other film orientations grew epitaxially with a cube-on-cube relationship. For CoCrFeMnNi, nanotwinning was observed on 50 % of the substrate grains, deviating < 35° from 〈111〉 . In the nanotwinned regions, the twin spacing was 10–100 nm for Ni and 2–20 nm for CoCrFeMnNi. The presence of nanotwins increased hardness in both materials. The mechanism behind these differences is discussed, together with other parameters for controlling twin density. Our results show that control of the growth process can be used for nanotwin-engineering in magnetron-sputtered materials with low SFE.