Width Of Loop Research Articles

Modeling of a tunable memory device made with a double-gate MoS2 FET and graphene floating gate

Electronic devices comprising low-temperature processed 2D materials can be utilized in back-end-of-line nonvolatile memory and logic applications, to augment conventional silicon technology. A promising structure for a low-temperature processed digital nonvolatile flash memory device and/or logic device is the double-gate MoS2 FET with a graphene floating gate and a thin h-BN gate dielectric serving as a tunneling dielectric. In this work, we show that experimental hysteretic current–voltage characteristics of this digital flash memory device can be well fit by a simple and effective physics-based model using a WKB approximation to calculate the tunneling current to the graphene floating gate and a capacitive network with 2D density-of-states to calculate the channel current flowing in the MoS2 channel. Accordingly, the model allows a device designer to predict and/or tune characteristics for this memory device, e.g., the width and center-position of the hysteresis loop as well as the value of source–drain current, as a function of both the bottom (control) gate and top (FET) gate voltages. It is noted that shifting of the center-position of the hysteresis loop enables improved reliability and functionality of the memory device in circuit applications and is a unique feature of this double-gated MoS2 FET. Overall, the demonstrated ability to well model this memory device lends further credence that 2D devices could augment silicon technology.

Hysteresis effect during reactive sputtering

In this work, we studied the effect of constant parameters of the sputtering system on the width of the hysteresis loop during reactive sputtering. The sticking coefficient of the reactive gas to the surface, the chamber pumping speed, the target area, etc. are taken as parameters. The comparative study was carried out by numerical solution of systems of algebraic equations describing the chemisorption and physicochemical models of metal target reactive sputtering in a single reactive gas. The calculations were performed for sputtering a tantalum target in an Ar + O2 mixture. The studied dependences were non-linear in all cases.

A 3D Printed Vitrification Device for Storage in Cryopreservation Vials.

Sperm cryopreservation by vitrification is a promising approach for small-bodied animals such as zebrafish (Danio rerio). However, most vitrification tools adopted in aquatic research were initially designed for applications other than sperm (such as human embryo freezing) and, thus, pose challenges for adoption to sperm vitrification. Three-dimensional (3D) printing combined with open hardware sharing is an emerging strategy to address challenges in the development of cryopreservation tools. The goal of this study was to develop a 3D printed Vitrification Device for Cryo-Vials (VDCV) that can be integrated with the existing vial storage systems. The VDCV combined the vitrification and handling components to achieve functions of sample handling, vitrification, storage, and identification. The vitrification component featured a base, a stem, and a loop. A total of 36 configurations with various loop lengths (8, 10, and 12 mm); loop widths (2.0, 2.5, 3.0, and 3.5 mm); and support structures (open, transverse, and axial) of the VDCD prototypes were designed, fabricated, and tested. Device handling orientations (horizontal and vertical holding angles prior to and during freezing) were also investigated. Computer simulations estimated that the cooling rate of the samples ranged from 0.6-1.5 × 105 °C/min in all the configurations. Prior to freezing, loops with axial supports produced a minimum of 92% film retention. The overall trends of full vitrification occurrence were observed: horizontal plunging > vertical plunging, and axial support > transverse support and open loop. A loop length of 8 mm had the highest overall vitrification occurrence (86-100%). No significant differences (p = 0.6584) were shown in a volume capacity (5.7-6.0 μL) among the three supporting configurations. A single unit of VDCV can provide loading efficiencies of about 6 × 107 sperm/vial, pooling of samples from 3-6 males/vial, and fertilization for 1800 eggs/vial. The VDCV are low-cost (<$0.5 material cost per unit) and can be customized, standardized, securely labeled, and efficiently stored. The prototypes can be accessed by user communities through open-fabrication file sharing and fabricated with consumer-level 3D printers, thus facilitating community-level standardization.

Fatigue behavior and damage evolution of SiC/SiC composites under high-temperature anaerobic cyclic loading

In the present study, the fatigue behavior and damage evolution of SiC/SiC minicomposites at elevated temperatures in oxygen-free environment are investigated which are important for their application and are still unclear. The high-temperature fatigue test platform is developed and the fatigue stress-life curve and the stress-strain response are obtained. The test result shows that the life of the material at elevated temperature is shorter than that at room temperature under the same stress level. Moreover, the hysteresis loop width and the residual strain increase with the increasing of the cycles while the hysteresis modulus decreases during the fatigue cycling. The evolution process of matrix cracks is observed using the real-time remote detection system. It is found that matrix cracking is insensitive to the cyclic loading which is similar to room temperature and is due to that the degeneration of the interfacial shear stress reduces the area of high stress in matrix. The fiber/matrix interfacial shear stress under different cycles is determined based on the fatigue modulus of each hysteresis loop. The result shows a fatigue enhancement phenomenon for the interface which is not observed at room temperature.

Electrical and optical properties of W-doped V2O5/FTO composite films fabricated by sol–gel method

V2O5/FTO composite films with different tungsten doping molar ratios were fabricated on soda-lime glass substrates by sol–gel spin coating method followed with annealing process. The analysis on crystallinity and surface morphology shows that W doping would induce V2O5 lattice distortion and make the film surface rougher. The resistance and transmittance during the phase transition process were measured to explore the electrical and optical properties of W-doped V2O5/FTO films. The results show that 3% W doping molar ratio is the most effective in improving the properties of V2O5/FTO films. The resistance of the prepared films is reduced by about three orders of magnitude from room temperature to 320℃. Compared to the undoped films, the 1%, 3% and 5% W-doped V2O5/FTO films possess higher conductivity and the width of the thermal hysteresis loop is narrowed from 14℃ to 13℃, 10℃ and 8℃, respectively. For undoped, 1%, 3% and 5% W-doped V2O5/FTO films, the phase transition temperature is 245℃, 238℃, 222℃ and 223℃, and the average transmittance decreased 7.7%, 7.8%, 11.7% and 5.7% in the range of 900–1400 nm before and after the phase transition, respectively.

Tunable optical bistability at microwave frequency based on 1D sandwich photonic structure consisting of a nonlinear dielectric slab and two magnetized cold plasma layers

In this paper, tunable optical bistability that denotes the relationship between input intensity and output intensity is numerically investigated in the microwave frequency region based on the one-dimensional (1D) sandwich photonic structure consisting of a Kerr-type nonlinear material slab and two magnetized cold plasma layers. Results show that, in the case of TM-polarized electromagnetic wave, width and switching thresholds of the bistability loops are dependent on the working frequency, initial incidence angle, layer thickness, plasma density, and external magnetic field, which should be judiciously selected to obtain a required bistability behavior. Compared to the case of switch-down threshold, the switch-up threshold in the bistability loop is more sensitive to the changes of parameters. Through this study, the suggested 1D sandwich photonic structure is beneficial to the all-optical signal processing.

Nailfold capillaroscopy: A sensitive method for evaluating microvascular involvement in children with SARS-CoV-2 infection

ObjectivesThe hyperinflammatory state and the viral invasion may result in endothelial dysfunction in SARS-CoV-2 infection. Although a method foreseeing microvascular dysfunction has not been defined yet, studies conducted in patients diagnosed with COVID-19 have demonstrated the presence of endotheliitis. With this study, we aimed to investigate the microvascular circulation in patients diagnosed with COVID-19 and multisystem inflammatory syndrome in children (MIS-C) by nailfold videocapillaroscopy (NVC). MethodsThirty-one patients with SARS-CoV-2 infection, 25 of whom were diagnosed with COVID-19 and 6 with MIS-C and 58 healthy peers were included in the study. NVC was performed in eight fingers with 2 images per finger and 16 images were examined for the morphology of capillaries, presence of pericapillary edema, microhemorrhage, avascular area, and neoangiogenesis. Capillary length, capillary width, apical loop, arterial and venous width, and intercapillary distance were measured from three consecutive capillaries from the ring finger of the non-dominant hand. ResultsCOVID-19 patients showed significantly more capillary ramification (p < 0.001), capillary meandering (p = 0.04), microhemorrhage (p < 0.001), neoangiogenesis (p < 0.001), capillary tortuosity (p = 0.003). Capillary density (p = 0.002) and capillary length (p = 0.002) were significantly lower in the patient group while intercapillary distance (p = 0.01) was significantly longer compared with healthy volunteers. Morphologically, patients with MIS-C had a higher frequency of capillary ramification and neoangiogenesis compared with COVID-19 patients (p = 0.04). ConclusionAbnormal capillary alterations seen in COVID-19 and MIS-C patients indicate both similar and different aspects of these two spectra of SARS-CoV-2 infection and NVC appears to be a simple and non-invasive method for evaluation of microvascular involvement.

High-Strength Suture Tapes Are Biomechanically Stronger Than High-Strength Sutures Used in Rotator Cuff Repair

PurposeTo assess the mechanical properties, tendon resistance to suture cutout, and knot size of a broad variety of high-strength sutures and tapes available for arthroscopic rotator cuff repair.MethodsNine different types of high-strength sutures and tapes for arthroscopic rotator cuff repair were studied: 6 were tapes (FiberTape, Hi-Fi Tape, Permatape, SutureTape, UltraTape, and XBraid TT), and 3 were sutures (Dynacord, FiberWire, and Ultrabraid). First, mechanical tensile testing of suture loops (n = 6) was performed. Second, the suture material was passed through an intact human cadaveric rotator cuff tendon (supraspinatus or infraspinatus), and cyclic as well as load-to-failure testing was performed, 8 times for each suture or tape. Statistical analysis of groups (tapes vs sutures) and between each suture and each tape was performed.ResultsMaterial testing revealed significant differences with superior mechanical properties of tapes compared with sutures regarding load for 3 mm of displacement (201 N vs 84 N, P < .0001), displacement at 200 N (3.6 mm vs 6.6 mm, P < .0001), stiffness (46 N/mm vs 25 N/mm, P < .0001), and ultimate load to failure (509 N vs 288 N, P < .0001). FiberTape showed the highest ultimate load to failure (805.5 ± 36.1 N), the highest load necessary for 3 mm of displacement (376.2 ± 19.1 N), and the lowest displacement at a 200-N load (2 ± 0.1 mm). Permatape had the highest stiffness (58.5 ± 5.3 N/mm). FiberTape had the highest knot height (9.5 ± 1.3 mm) and knot width (3.8 ± 0.7 mm) of a suture loop with 7 square knots. The typical failure mode in the cadaveric study part was tendon cut through.ConclusionsBiomechanical in vitro testing showed that high-strength suture tapes compared with regular high-strength sutures have significantly better mechanical properties in both dry-laboratory testing and human cadaveric rotator cuff tendon pullout testing. FiberTape outperformed the other tapes and the sutures used in this analysis. Nonetheless, differences in tendon testing appeared to be less substantial than in dry-laboratory testing, and FiberTape had the highest knot height and width.Clinical RelevanceFiberTape revealed the most favorable biomechanical performance in dry-laboratory and rotator cuff tendon testing. It may provide the best repair strength in vivo; however, it also has the largest knot size.

Vanadium oxide thin films with extremely narrow thermal hysteresis loop width were obtained by Ta doping for THz modulation applications

Based on the application potential of VO2 thin film in THz modulation field, only keeping its modulation amplitude is no longer applicable, and the film also needs to have lower phase transition temperature and narrower loop width, etc. In order to solve this problem, and since the high valence ion doping can reduce the phase transition temperature of VO2 films, the effect of Ta5+ doping on the phase transition performance of VO2 films is studied and analyzed in this paper. In this work, based on DC reactive magnetron sputtering technology, un-doped and Ta-doped VO2 films were prepared on high-resistance silicon substrate by two-step method. The microstructure of VO2 films before and after Ta doping was characterized by XPS, XRD and SEM images to assist the study and analysis of the influence of Ta5+ ions on the crystal phase structure of VO2. Finally, when the doping concentration of Ta5+ is 0.71%, the phase transition temperature (TC) of VO2 film decreases to 37.5 °C, the loop width (ΔH) narrows to 1.03 °C, and the optical modulation amplitude is maintained at 64.2%, which makes it more suitable for THz modulator.

Calculation of interlock, 1 × 1 rib, and single jersey knitted fabrics shrinkage during the dyeing process after determining loop shape

This study investigated existing dimensional variations in knitted fabrics produced by weft-knitting technology for knitting and dry relaxation, dyed and dry relaxation, and dyed and wash relaxation for the interlock, 1 × 1 rib, and single jersey structures. This paper demonstrates that once the structure has been knitted, the shape that the loop takes in the fabric, and loop length and loop width, for each relaxation state will be the main factor responsible for dimensional variations in cotton knitted fabrics. It also shows how loop length affects knitted fabric dimensions when knitting machine parameters are modified by varying the use of feeders, and obtaining more loosely or more tightly knitted fabrics. In this study a model to predict the longitudinal and transversal shrinkage of interlock, 1 × 1 rib, and single jersey fabrics after the dyeing process is presented. This avoids following the conventional analysis procedure according to Standard UNE-EN ISO 6330 of September 2012 and, thus, avoids investing relatively long calculation times, which speeds up the production process by avoiding product lots being stopped. These results are important for textile industry technicians as they substantially simplify production calculations in weft-knitted fabrics companies. This work offers an effective method for predicting the longitudinal and transversal shrinkage and width of knitting fabrics after the dyeing process from the loop dimension after the knitting process. The application of the study results may help businesses to significantly save time and, consequently, imply an intermediate product stock investment saving.

Nailfold videocapillaroscopic changes in patients with pulmonary arterial hypertension associated with connective tissue diseases.

Pulmonary arterial hypertension (PAH) represents one of the most devastating complications in connective tissue diseases (CTDs). The aim of this study was to investigate the presence of peripheral microangiopathy in patients with PAH associated with CTDs (CTD-PAH) by exploring nailfold videocapillaroscopic (NVC) changes and identify possible associations of NVC characteristics with markers of disease severity. Α cross-sectional study was performed in 18 CTD-PAH patients [13 PAH due to systemic sclerosis (SSc-PAH) and 5 with other types of CTD-PAH], 14 patients with SSc without PAH (SSc-non-PAH) and 20 healthy controls. NVC quantitative and qualitative parameters were evaluated using Optilia Digital Capillaroscope. To ensure inter-observer repeatability, capillaroscopic images were reviewed by two independent investigators. When compared to healthy controls, patients with CTD-PAH (77.8% women, mean age 65.9years) presented reduced capillary density (6.5 ± 1.6 loops/mm vs. 9.7 ± 0.7 loops/mm, p < 0.001) and increased capillary loop width (23.3 ± 10.1μm vs. 11.2 ± 2.5μm, p < 0.001). SSc-PAH patients presented lower capillary density in comparison with other CTD-PAH patients and SSc-non-PAH subjects and abnormal and disorganized capillaries compared to controls. Patients with other CTD-PAH had also reduced capillary density and increased loop diameter compared to controls. A significant linear correlation was identified between capillary density and estimated glomerular filtration rate in the total CTD-PAH population (r = 0.63, p = 0.007). In SSc-PAH group, capillary loop diameter was positively correlated to cardiac index (r = 0.61, p = 0.02). Significant NVC microvascular changes were detected in patients with various types of CTD-PAH, suggesting an impaired peripheral microcirculation parallel to pulmonary vasculopathy.

Micromechanical modeling cyclic loading/unloading hysteresis loops of 3D needle-punched C/SiC ceramic-matrix composites

ABSTRACT In this paper, the 3D needle-punched C/SiC composite was fabricated using the chemical vapor deposition and reactive infiltration method. Four different fiber preforms were formed using the needled-punch technology. The PyC interphase was deposited on the surface of the fibers to increase the toughness of the composite under tensile loading. Cyclic loading/unloading tensile tests were conducted at different peak stresses. A micromechanical hysteresis constitutive relationship was developed considering damage mechanisms of matrix cracking, interface debonding and slip, and fiber’s fracture and pullout. Using the developed hysteresis loops models and damage models, the hysteresis loops of four different types of 3D needle-punched C/SiC composites were predicted for different peak stresses. The hysteresis parameters of unloading residual strain, peak strain, hysteresis loops width, hysteresis loops area, interface slip ratio, and inverse tangent modulus were adopted to characterize the tensile damage evolution inside of composites. Relationship between composite’s hysteresis behavior and microstructure damage evolution is established. It was found that the composite’s hysteresis loops depend on the fiber’s preform and interface properties.

Growth of nanostructured VO2 via controlling oxidation of V thin films: Morphology and phase transition properties

Vanadium dioxide (VO2), which exhibits a metal–insulator phase transition at 70 °C, is known to alter its physical properties according to its surface morphology and fabrication process. The systematic investigation of a new fabrication method could not only clarify the origin of its phase transition but also advance progress in applications employing VO2 nanostructures. Here, we demonstrate the drastic enhancement of both the surface morphology and hysteresis of VO2 nanostructures composed of nanoparticles, by applying a sputtering deposition fabrication process, followed by lamp annealing. We investigated different growth conditions for VO2, especially using metallic precursor oxidation under a controlled pressure and temperature, and found that each growth condition led to different morphologies, nanoparticle sizes, and phase transition properties (hysteresis width). Despite a slight increase in particle diameter with annealing time and O2 pressure, the particle aggregation was found to substantially decrease. The temperature width of the hysteresis loop obtained by infrared light reflection measurements increased as the aggregation of VO2 nanoparticles decreased. During the cooling procedure, the transition of slightly aggregated VO2 nanoparticles was revealed to be a two-step process, with the lower transition temperature decreasing with an increase in particle isolation. Our results have the potential to elucidate the hysteresis-inducing mechanisms in VO2 and to aid the materialization of novel devices such as passive thermal control and thermal memory devices.

Nailfold Capillaroscopy in Systemic Sclerosis Patients with and without Pulmonary Arterial Hypertension: A Systematic Review and Meta-Analysis

Systemic sclerosis (SSc)-related pulmonary arterial hypertension (SSc-PAH) is a leading cause of mortality in SSc. The extent of peripheral microvasculopathy assessed through nailfold capillaroscopy might correlate with the presence of PAH in SSc patients. We searched the PubMed, Cochrane Library, Scopus, and Web of Science databases and performed a random effects meta-analysis of observational studies comparing nailfold capillaroscopic alterations in SSc-PAH versus SSc-noPAH patients. Weighted mean differences (WMD) with the corresponding confidence intervals (CIs) were estimated. The quality of the included studies was evaluated using a modified Newcastle–Ottawa scale. Seven studies with 101 SSc-PAH and 277 SSc-noPAH participants were included. Capillary density was marginally reduced in the SSc-PAH group (WMD: −1.0, 95% CI: −2.0 to 0.0, I2 = 86%). This effect was strengthened once PAH diagnosis was confirmed by right heart catheterization (WMD: −1.2, 95% CI: −2.3 to −0.1, I2 = 85%). An increase in capillary loop width was observed in SSc-PAH compared to SSc-noPAH patients (WMD: 10.9, 95% CI: 2.5 to 19.4, I2 = 78%). Furthermore, SSc-PAH patients had a 7.3 times higher likelihood of active or late scleroderma pattern (95% CI: 3.0 to 18.0, I2 = 4%). SSc-PAH patients presented with worse nailfold capillaroscopic findings compared to SSc-noPAH patients.

Grid-Assisted Co-Sputtering Method: Background, Advancement, and Prospect

In this paper, the incorporation of auxiliary grids/electrodes into the design of the sputtering method is scrutinized by studying the impact of factors such as grid size, grid position, grid bias voltage, electrode sheath design, substrate bias voltage, reactive gas partial pressure, and magnetic trap configuration on the discharge condition and thin-film growth. In this regard, utilizing the updated Berg model for reactive sputtering, the authors obtained a formulation for the reactive grid-assisted sputtering. By the newly-developed formulation, the sputtering rate and the reactive gas partial pressure were simulated as a function of the reactive gas flow rate for various grid-to-target distances, argon partial pressures (0.67, 1.6, and 3.6 Pa), and discharge current densities (0.01, 0.015, and 0.02 A/cm2). According to the computation results, with a grid being utilized, the width of the hysteresis loops can be modified in a broader range by changing either the grid-to-target distance, the argon partial pressure, or the discharge current, resulting in better control over the deposition process. Moreover, the novel configuration of anode-spot-assisted sputtering was proposed to significantly ionize sputtered/neutral atoms near the substrate and to simultaneously deposit sputtered species and products produced as the direct result of introducing dust into the dense plasma. Finally, diverse configurations of the grid-assisted co-sputtering method were introduced for two prime purposes: deposition of composite films in any desired ratios of constituents without significantly changing the other co-sputtering parameters, and favorable alternation of a hysteresis loop for one of the guns at shared gas flow rates.

Peripheral microangiopathy in Eisenmenger syndrome: A nailfold video capillaroscopy study

BackgroundEisenmenger syndrome (ES) comprises a severe phenotype of pulmonary arterial hypertension characterized by angiopathy of the lung circulation. The aim of the present study was to demonstrate the presence of systemic microvascular abnormalities in patients with ES using nailfold video-capillaroscopy (NVC) and to identify potential correlations of nailfold capillaroscopic characteristics with non-invasive markers of systemic organ function. MethodsΑ cross-sectional NVC study was performed in 17 consecutive patients with ES and 17 healthy controls matched for age and sex. NVC quantitative (capillary density, capillary dimensions, haemorrhages, thrombi, shape abnormalities) and qualitative (normal, non-specific or scleroderma pattern) parameters were evaluated. ResultsPatients with ES [median age 40 (18–65) years, 11 women] presented reduced capillary density [8.8 (7.2–10.2) loops/mm vs. 9.9 (8.3–10.9) loops/mm, p = .004] and increased loop width [15.9 (10.3–21.7) μm vs. 12.3 (7.6–15.2) μm, p < .001], while they had significantly more abnormal capillaries than healthy controls [2.5 (0.9–5.4) abnormal loops/mm vs. 1.0 (0.0–1.7) abnormal loops/mm, p < .001]. NVC shape abnormalities in ES were positively correlated with NT-proBNP (r = 0.52, p = .03) and were negatively associated with estimated glomerular filtration rate (r = −0.60, p = .02). Additionally, capillary loop diameter was positively correlated with increased haemoglobin levels (r = 0.55, p = .03) and negatively correlated with reduced peripheral oxygen saturation (r = − 0.56, p = .02). ConclusionsThis study supports the hypothesis of peripheral microvascular involvement in ES parallel to pulmonary microangiopathy detected by NVC. Further longitudinal studies are needed to confirm our preliminary results.

Hysteretic Behaviors of Separation-Shock Driven by Backpressure in Isolator with Incident Shocks

Experimental and theoretical studies are performed to analyze the hysteresis of the separation shock caused by shock-wave/boundary-layer interaction (SWBLI). Results from the schlieren images exhibit the spatial distribution of the power spectrum of the shock oscillation during the process of passing through the SWBLI region. This distribution indicates that the downstream region of the SWBLI tends to excite the oscillation with a higher power and longer duration. In the periodic motion, the relationship between the velocity of the first separation shock and the varying rate of the downstream pressure shows that the downstream region of the SWBLI has slight retardation on the movement of the separation shock. The analysis based on the dynamic model indicates that the hysteresis of the separation shock in this situation is caused by the nonlinear relationship between the length of the shock system and the flow condition, which forms a dual solution in the pressure distribution within the shock system. When the flap varying rate is below a certain value, the width of the hysteresis loop maintains as the same, which is determined by the distributions of the flow parameters; whereas with a larger varying rate, the dynamic feature of the separation shock should be considered.

Spin-Crossover 2-D Hofmann Frameworks Incorporating an Amide-Functionalized Ligand: N-(pyridin-4-yl)benzamide

Two analogous 2-D Hofmann-type frameworks, which incorporate the novel ligand N-(pyridin-4-yl)benzamide (benpy) [FeII(benpy)2M(CN)4]·2H2O (M = Pd (Pd(benpy)) and Pt (Pt(benpy))) are reported. The benpy ligand was explored to facilitate spin-crossover (SCO) cooperativity via amide group hydrogen bonding. Structural analyses of the 2-D Hofmann frameworks revealed benpy-guest hydrogen bonding and benpy-benpy aromatic contacts. Both analogues exhibited single-step hysteretic spin-crossover (SCO) transitions, with the metal-cyanide linker (M = Pd or Pt) impacting the SCO spin-state transition temperature and hysteresis loop width (Pd(benpy): T½↓↑: 201, 218 K, ∆T: 17 K and Pt(benpy): T½↓↑: 206, 226 K, ∆T: 20 K). The parallel structural and SCO changes over the high-spin to low-spin transition were investigated using variable-temperature, single-crystal, and powder X-ray diffraction, Raman spectroscopy, and differential scanning calorimetry. These studies indicated that the ligand–guest interactions facilitated by the amide group acted to support the cooperative spin-state transitions displayed by these two Hofmann-type frameworks, providing further insight into cooperativity and structure–property relationships.

Control of Polymorphic Properties of Multivalent Vanadium Oxide Thin Films

In this study, VxOy thin films were deposited on borosilicate glass substrates using direct current (DC) magnetron sputtering. The optoelectronic thermochromic properties of the resulting multiphase vanadium oxide thin films were investigated. As-deposited (at 280 °C) films were annealed at 350, 450, and 500 °C in an oxygen atmosphere for 30 min in a tube furnace to improve the crystallinity. Structural analysis indicated the formation of a mixed-phase vanadium oxide film consisting of VO2(B), V4O9, and V2O5 phases on the amorphous substrate after annealing above 350 °C. The results showed that the semiconductor-to-metallic phase transition temperature of the vanadium oxide film increased from 48 to 63 °C with increasing annealing temperatures. The sample annealed at 450 °C exhibited the highest variation in the infrared (IR) transmittance (ΔTIR = 28.42%) and the resistivity switch decreased by two orders of magnitude (1.4 × 10–1–2.3 × 10–3 Ω/cm). The thermal treatment temperature affected the width of the thermal hysteresis loop (HLW) and slope stiffness. A narrower HLW of 1.9 °C and a sharp slope stiffness of 8.74 were obtained for the sample annealed at 500 °C. The slope stiffness plays an important role in the fabrication of ultrafast tunable energy-saving smart windows and IR switches.

Crystal structure and magnetic properties study on barium hexaferrite (BHF) and cobalt zinc ferrite (CZF) in composites

The composite of BaFe12O19 (BHF) and CoFe1·75Zn0·25O4 (CZF) with different weight percentages have been synthesized by using the high energy planetary ball mill technique. The obtained powders have been characterized by employing the X-ray diffraction, Field Emission Scanning Electron Microscope, and Energy Dispersive X-ray analysis techniques. The lattice parameters and phase percentage have been obtained by the Rietveld refinement analysis of XRD peaks. The crystallite sizes of BHF are greater than the CZF. The magnetic hysteresis loops have been recorded by using the Vibrating Sample Magnetometer (VSM) for all samples. The magnetic interaction between BHF and CZF in the composite has been investigated by plotting the loop width (ΔH) versus magnetization (M). The shape of these curves between loop width versus magnetization is changed with a different weight percentage of BHF and CZF. The saturation magnetization increases with an increase in the concentration of CZF in the composites. Vegard's law is used for comparing the theoretical and experimental magnetic parameters. The squeezing in hysteresis loop at H = 0 vanishes for (55)% BHF + (45)%CZF sample below 150 K and interesting magnetic interaction between two phases has been observed.