Tungsten is one of the prime candidates for a first-wall material near the divertor area due to its high temperature strength, high thermal conductivity, low erosion rate and low tritium retention. ...The erosion resistance of tungsten to the edge plasmas and transient events are carefully investigated in a simulated fusion environment. Here, we use the dense plasma focus (DPF) device operated in a D
2
as a source for pulsed fusion plasma. The tungsten (α-W) substrates with a preferential growth direction along (110) plane were used. These pristine-W samples were nanostructurized using a (i) low-temperature continuous nitrogen RF plasma system and (ii) coated with 60 nm tungsten film, using high-temperature argon plasma in a dense plasma focus (DPF) device. The low- temperature plasma treatment created mesh-like porous nanostructure on the surface of pristine-W with change in crystalline orientation to (200), while the DPF-based deposition resulted in a nanocrystal (30–50 nm) decorated surface with enhanced (200) orientation. The crack propagation and bubble formation during DPF D
2
plasma exposure were significantly controlled by the surface modification of tungsten. The mesh-like structure was modified to form loosely bound spherical nanoparticles, while the nanocrystals remained tightly bound and grew in size with D
2
plasma exposure. The better adhesion of the nanocrystals and controlled growth along the (200) direction resulted in least change in hardness measurements for the nanocrystal decorated samples. Thus, nanocrystal decoration of tungsten with a preferential growth direction of (200) can help reduce the fusion-induced damage in first-wall materials.
In order to improve the tracking and erosion performance of outdoor polymeric silicone rubber (SR) insulators used in HV power transmission lines, micron sized inorganic fillers are usually added to ...the base SR matrix. In addition, insulators used in high voltage dc transmission lines are designed to have increased creepage distance to mitigate the tracking and erosion problems. ASTM D2303 standard gives a procedure for finding the tracking and erosion resistance of outdoor polymeric insulator weathershed material samples under laboratory conditions for ac voltages. In this paper, inclined plane (IP) tracking and erosion tests similar to ASTM D2303 were conducted under both positive and negative dc voltages for silicone rubber samples filled with micron and nano sized particles to understand the phenomena occurring during such tests. Micron sized Alumina Trihydrate (ATH) and nano sized alumina fillers were added to silicone rubber matrix to improve the resistance to tracking and erosion. The leakage current during the tests and the eroded mass at the end of the tests were monitored. Scanning Electron Microscopy (SEM) and Energy dispersive Xray (EDX) studies were conducted to understand the filler dispersion and the changes in surface morphology in both nanocomposite and microcomposite samples. The results suggest that nanocomposites performed better than microcomposites even for a small filler loading (4%) for both positive and negative dc stresses. It was also seen that the tracking and erosion performance of silicone rubber is better under negative dc as compared to positive dc voltage. EDX studies showed migration of different ions onto the surface of the sample during the IP test under positive dc which has led to an inferior performance as compared to the performance under negative dc.
In situ Formula Omitted–Formula Omitted and Formula Omitted–Formula Omitted measurements were performed on Pt/PtOx/Formula Omitted-Ga2O3 vertical Schottky barrier diodes (SBD) during 120 MeV Au9+ ...swift heavy ion (SHI) irradiation in a fluence range of Formula Omitted–Formula Omitted ions/cm2. The reverse leakage current density increased from Formula Omitted to Formula Omitted A/cm2 at −1 V. The Schottky barrier height (SBH) remains close to ~1.8 eV up to the fluence of Formula Omitted ions/cm2, and however, at the fluences of Formula Omitted and Formula Omitted ions/cm2, the SBH increased to 1.93 and 2.03 eV, respectively. Also, the ideality factor (IF) increased from 1.07 to 1.38. The in situ Formula Omitted–Formula Omitted measurements showed a similar trend, as the SBH decreased from 2.04 to ~1.88 eV until Formula Omitted ions/cm2, but it increased to 2.14 and 2.56 eV at Formula Omitted and Formula Omitted ions/cm2, respectively. In addition, the doping concentration decreased from Formula Omitted to Formula Omitted cmFormula Omitted as the defects increased significantly at the fluence of Formula Omitted ions/cm2. The cathodoluminescence measurements revealed various Ga and O defects produced during SHI irradiation. Cross-sectional transmission electron microscopy measurements confirmed the formation of tracks within Formula Omitted-Ga2O3 along the SHI path, and these results are explained with the inelastic thermal spike model.
In situ Formula Omitted and Formula Omitted measurements were performed during the 120 MeV AuFormula Omitted ion irradiation on the Pt/AlFormula Omitted-Ga2O3, metal–oxide–semiconductor capacitors ...(MOSCAPs), to comprehend the swift heavy ion (SHI)-induced effects at the interface and in the device performance. At a maximum fluence of Formula Omitted ions/cm2, the Formula Omitted data showed a rise in the reverse leakage current by four orders of magnitude compared to the pristine device. The trap level (below the conduction band of Al2O3) from Poole–Frenkel emission exhibits a variation from Formula Omitted1.1 to 0.91 eV. The conduction band offset Formula Omitted of AlFormula Omitted-Ga2O3 changes from 1.48 to 1.25 eV as estimated under the Fowler–Nordheim tunneling mechanism. In situ Formula Omitted measurements show a significant shift in the flat band voltages and increased oxide in the border and interface due to charge trapping. The X-ray photoelectron spectroscopy (XPS) measurements of Al 2p and O 1s core levels revealed the pre-existing oxygen defects in Al2O3, which increase with fluence. The deconvoluted peaks of Al 2p at 74.6 eV designated to Al-sub oxide and the O 1s peak variation in the FWHM signifies the increase in the O defects. Cross-sectional transmission electron microscopy (XTEM) measurements on the irradiated device (at Formula Omitted ions/cmFormula Omitted revealed a modulated interface of AlFormula Omitted-Ga2O3 and the formation of an interlayer of Formula Omitted4 nm Al x GayOz. The scanning transmission electron microscope (STEM)-based high-angle annular dark-field imaging (HAADF) energy-dispersive X-ray spectroscopy (EDS) mapping revelation and the depth profiles of XPS data confirm the formation of an Al x GayOz interlayer.
We report the facile synthesis of nanostructured polycrystalline nickel sulphide (NP-Ni3S2) on Ni foil at 750 and 800 °C by employing powder vapor transport technique. X-ray diffraction patterns ...(XRD) confirms the formation of polycrystalline Ni3S2 phase with rhombohedral structure. Raman spectroscopy and x-ray photo-electron spectroscopy (XPS) further confirms the formation of Ni3S2 phase. Scanning electron microscopy (SEM) reveals the formation of flower shaped nanostructures of NP-Ni3S2 material. As an electrode material of Li+ batteries, the initial discharge capacities for NP-Ni3S2 materials deposited at 750 and 800 °C are found to be ∼2649 mAh g−1 and ∼1347 mAh g−1, respectively with initial capacity loss of ∼1067 mAh g−1 and ∼363 mAh g−1 after first cycle and capacities of ∼931 mAh g−1 and ∼818 mAh g−1 after 30 cycles for a current density of 60 mA g−1. An excellent capacity retention for NP-Ni3S2 material synthesized at 800 °C is due to its larger surface area and shorter diffusion length for mass and charge transport brought about by the flower-like porous nanostructures showing that the NP-Ni3S2 material synthesized at higher temperatures is more suitable as electrode material for Li+ batteries.
Developing flexible multiferroic composite with magnetoelectric coupling is highly desirable for the wearable electronic devices, magnetic field sensors, actuators, energy harvesters and memory ...devices. Here, a flexible artificial multiferroic composite was fabricated using ferromagnetic nickel ferrite (NiFe2O4) nanoparticles (NPs) as filler in the ferroelectric polyvinylidene fluoride (PVDF) matrix. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) studies revealed the formation of the inverse spinel phase in NiFe2O4 NPs. The vibrating sample magnetometer (VSM) and XRD measurements showed an increase in the magnetic moment and the electroactive β phase fraction, respectively, in PVDF/NiFe2O4 composite with the increasing loading concentration of NiFe2O4 filler NPs. With the increase in NiFe2O4 NPs loading concentration to 40 wt % the magnetoelectric coupling between the ferroelectric (PVDF) and ferromagnetic (NiFe2O4 NPs) was confirmed using magnetocapacitance measurement. This work successfully demonstrates the potential of artificial multiferroic PVDF/NiFe2O4 composite system, with enhanced dielectric property and room temperature magnetoelectric coupling, for future flexible electronic devices.
Graphene has gained lot of attention due to its exception properties of high electron mobility, electric current carrying capacity, high optically transparency and considered as an excellent ...candidate for next-generation optical and electrical devices. The interface between graphene and silicon has been shown to form a Schottky barrier, which exhibits rectifying properties - allowing current to flow in one direction, enabling its use as an electrical diode. Furthermore, graphene's optical transparency, along with its strong optoelectronic response, allows the generation of photocurrent by the graphene-silicon diode when absorbing light, making it suitable for use as a high-sensitive photodetector with higher responsiveness and improved light-to-dark current ratio.
Plasma Focus devices are receiving attention in the field of plasma nanotechnology, particularly for the synthesis of nanostructured carbon and carbon thin films, since they are a good source of high ...energy ionic species. For attaining greater control over the deposition and processing of materials, the appropriate ion energies and ion flux and the control over plasma dynamics need to be achieved to make this process reliable and repeatable. One of the main parameter to achieve this control is the electrode dimensions, operating gas pressure, and gas mixture ratio in plasma focus device. We kept the operating voltages same. For example, to limit the amount of material deposited, it might be necessary to dilute the reactive gaseous environment with inert gases like He, N e or Ar. The dilution/mixture can affect the pinch dynamics inside the plasma focus device. In the present study, we report the use of different diagnostics, such as electrical probes and fast-gated imaging, to understand the pinch and post pinch plasma dynamics under methane gas operation mixed with neon and argon gases. In order to increase the pinch plasma volume for more material synthesis the experiments were also performed with modified plasma focus device with larger diameter anode. Elongated and larger volume pinch plasma column together with multiple pinches during later half-cycles of current discharge were obtained. These results will be discussed in detail during the conference.
PDF
