Minimum Resistivity Research Articles

Rocksalt-type PrO epitaxial thin film as a weak ferromagnetic Kondo lattice

A unique Kondo lattice praseodymium monoxide PrO was synthesized in the form of an epitaxial thin film. The rocksalt-type PrO thin films with a $4{f}^{2}5{d}^{1}$ electronic configuration showed metallic conduction with a local resistivity minimum at 7 K as a result of the Kondo effect. In contrast to the other paramagnetic praseodymium monochalcogenides, PrO showed weak ferromagnetism below 28 K, followed by a transition to a more ferromagneticlike phase around 5 K. Emergence of the weak ferromagnetism probably originated from the enhanced $4f\text{\ensuremath{-}}4f$ exchange interaction by the short Pr-Pr distance. For the ferromagneticlike phase below 5 K, magnetic hysteresis of the anomalous Hall effect was significantly larger than that of magnetization, probably due to competing magnetic ordering.

Effect of Al-Doped on the Electrical Properties of Nb<sub>2</sub>O<sub>5</sub> Film Prepared by DC. Plasma Sputtering Technique

Thin films of Niobium oxide (Nb2O5) co-doped with (0.5, 1, and 1.5) %wt. percentages of Aluminum (Al) were prepared on glass substrates by DC. Sputtering plasma technique. The effects of Al concentration on structural, surface morphology, optical and electrical properties of transparent were investigated. Polycrystalline structures without any second phases were observed with preferential orientations along the (001), (100), (101), (002), and (111) planes. The crystalline size as determined from the (001) peaks lay in the range (20-50) two theta and all films of Nb2O5: Al films have pseudohexagonal phase. It was observed that Al doping reduced the crystal size but at the samples 0.5%Al the crystalline size increased slightly. Also, it's observing from SEM images an increase in particle size after Al-doped. The minimum resistivity was found to be 4.79 x104 (Ω.cm) for the Nb2O5 doped with 1.5%Al concentration and maximum resistivity was found to be (4.86 x104 (Ω.cm) for the pure Nb2O5. The doping to the optimum level of 1.5% Al concentration increases the electrical conductivity of Nb2O5. The mobility decreased but the sample 1.5%Al concentration increases and the carrier concentration increased with increasing the doping with Al but the sample 1.5%Al concentration decreases. The analysis of Hall coefficient showed the Nb2O5: Al films were n-type.

Effects of zinc doping on structural, morphological, optical and electrical properties of SnO2 thin films

The aim of the present study was to deposited and characterized Zn-doped SnO2 thin films for different weight concentrations (wt.%) 0, 3, 5 and 7% produced by spray pyrolysis. The characterization by XRD showed that the layers are polycrystalline in nature, with tetragonal structure of rutile type due to the presence of intense peak of orientation (110) located around the angle 26° for all the films produced. The variations in FWHM and the crystallite size were very well correlated. The SEM micrograph shows a relatively dense and smooth surface exhibited by the 3 wt.% doped film. This result can be explained by considering the following reasons: the substitution of the Sn+4 cations for the Zn+2 cations facilitate, the crystallite size increase and the decrease in defects. The contact angles measured using water droplets were less than 90° for all the films produced, which proves the hydrophilic characteristic of the films, meanwhile the film doped with 3 wt.% Zn had a high contact angle (88.09°). This result suggests that a doping concentration equal to 3 wt.% Zn can be considered as a critical concentration in changing the surface morphology of the Zn-doped SnO2 films produced. The analysis by UV-visible spectrophotometer showed a transmittance varying between 76 to 87% depending on the doping. The 3 wt.% Zn-doped SnO2 film was found to have high transmittance (87%) and better optical property with minimum resistivity (ρ = 0.044 Ω cm) among the deposited films. This work demonstrated that the 3 wt.% Zn-doped SnO2 film improves the physical properties of the SnO2 film, allowing it to be integrated into the optoelectronic device.

Effect of milling duration on structural properties of polycrystalline bulk barium hexaferrite

Polycrystalline bulk Barium hexaferrite, BaFe12O19 were synthesised by ball milling for different milling duration followed by sintering at high temperature. Effect of milling duration on structural, morphological and dc electrical properties were studied for 4, 8, 12 and 16 h of milling using planetary ball mill. X-ray diffraction measurement data shows the formation of single phase barium hexaferrite which belongs to P63/mmc group for 8, 12 and 16 h milled samples. There is formation of intermediate phase along with M−phase of barium hexaferrite in 4 h milled sample. Inverse relation of the crystallite size and lattice strain was observed. The saturation value of crystallite size and maximum lattice strain were observed for 12 h milled sample. Morphological studies for 8 and 16 h milled samples reveals the formation of hexagonal plate like grains for the former and agglomerates with different grain size for the latter. High porosity for 8 h milled sample was observed by density measurements. Resistivity of the samples measured from I-V characteristics using 2 probe method exhibits maximum resistivity for 8 h milled sample and minimum resistivity for 12 h milled samples. Linear relationship was observed between electrical resistivity and porosity.

UV-irradiated sol-gel spin coated AZO thin films: enhanced optoelectronic properties

Thin films of transparent conductive Al doped ZnO (AZO) thin films were produced via sol-gel spin coating route. Structural, optical, and electrical properties were explored for several dopant concentrations. Formation of crystalline AZO was verified by X-ray Diffraction (XRD) Analysis and structural analysis were carried out later from the XRD data. Highest band gap of 3.67 eV was found for 2 mol % AZO thin films. The average transmittance was found to be 84.19% in the visible spectra for the corresponding thin films. 2 mol% AZO also exhibited a minimum resistivity of 2.05 Ω-cm with a maximum value of figure of merit. Prolonged UV irradiation was applied to 2 mol % AZO thin films prior to annealing. It significantly modified the surface morphology of the film and provided shielding near UVA (315–378 nm) spectrum. This also enhanced the conductivity of the thin film by 3-fold compared to non-UV treated sample and decreased optical band gap significantly.

ТЕОРЕТИЧНИЙ АНАЛІЗ СИЛ ОПОРУ ПЕРЕМІЩЕННЮ УДОСКОНАЛЕНОГО ПІДКОПУЮЧОГО РОБОЧОГО ОРГАНУ КАРТОПЛЕЗБИРАЛЬНОГО КОМБАЙНА

The amount of energy required to perform technological processes in agriculture largely depends on the size of the resistance to the displacement of the working bodies of machines. The main factor of energy consumption performing the technological process of potato harvesting is the resistance to the displacement of the digestive working body. In order to reduce the resistance to displacement an improved design of the digging body is proposed. An analytical study was conducted to determine the problem of moving the working body in the soil environment. The strength of the soil resistance is determined and the regularity of the influence on its change of parameters and the shape of the blade and separation parts of the digging working body is established. Calculations are made using the Mathematica application programm. The graphic dependences and contours of the isoline of the traction flange of the working part of the working body are obtained. Analysis of the calculations allowed to set the parameters of the surface of the dashboard, which provide a minimum of traction resistance. The schedule and contours of isolines of the change of the total resistance to the displacement of the soil mass with the tubers by the separation surface of the working organ in the function of the distance between the bars and the size of their intersection are also obtained. Analysis of the dependence of soil resistance and tubers on the separation surface indicates that an increase in the size of the geometric size of the intersection of the rods leads to a significant increase in the resistance of the medium. The material presented in the article can be used for analytical determination of the resistance of the excavation working body of potato harvesting machines of arbitrary geometric shape in the soil medium with tubers.

Resistivity Method for Characterising Subsurface Layers of Coastal Areas In South Sulawesi, Indonesia

The data presented in this paper are related to the characterization of a subsurface layer of coastal area in South Sulawesi. This research will fill the gap in the resistivity method study which is this method not yet use in the coastlines area, especially area influenced by seawater and coastal condition impact like South Sulawesi. The method used in this study is the method of resistivity Wenner configuration by taking the data 1-2 lines each region with lengths 45 m, 75 m, 105 m, and 120 m respectively. Data processing using non-linear least square optimization with that of the 2D inversion software Res2Dinv. The results show that the area is underlain by two layers of lithologic sections. In some sections interpreted by sandy layer, clay, sandstone, alluvium, sandy in seawater and metal minerals. From the analysis of the layers, all regions show the resistivity minimum is 0.00849 Ωm and 8.04 Ωm maximum resistivity. The result of this research can give n insight to study the large coastal area subsurface.

Graphene coated cotton nonwoven for electroconductive and UV protection applications

The functional properties and applications of graphene coated textiles depend on the magnitude of graphene add-on which in turn is influenced by the type of substrate and the dipping conditions. In the present study, optimized GO (graphene oxide) dipping conditions are identified for the preparation of cost-effective and scalable rGO (reduced graphene oxide) coated cotton nonwoven for electroconductive and UV (ultraviolet) blocking applications. To understand the influence of GO dipping variables on rGO add-on and electrical resistivity of cotton, batch adsorption studies are carried out in loose fibre form to eliminate the structural influence of yarn or fabric. Batch adsorption studies suggest that GO concentration, pH of GO solution and sodium dithionite (reductant) concentration are the most influencing dipping variables and these dipping variables are optimized for cotton nonwoven fabric using Box–Behnken response surface design to achieve minimum surface resistivity. The rGO coated cotton nonwoven fabric shows excellent UV blocking properties (UV protection factor = 89.38) at the optimized GO dipping conditions. Physical properties of cotton nonwoven fabric such as GSM, thickness, stiffness, breaking strength and elongation are analysed at different dipping cycles. After the rGO coating, bending rigidity, bending modulus and breaking elongation of the cotton nonwoven fabric decrease, whereas the breaking strength increases. rGO coated cotton fabric exhibits excellent stability towards multiple washing and rubbing. The graphene coated cotton is characterised by FT-IR, XRD, Raman, TGA, FESEM and LEICA image analyser.

Observation of novel coexistence of Kondo effect and room temperature magnetism in AlN/Al/AlN trilayer thin film

In this work for the first time, we are reporting the unusual observation of the Kondo effect with the coexistence of room temperature ferromagnetism in AlN/Al/AlN trilayer thin film. The grown film shows resistivity minimum at a temperature of ∼48K, which shifts to the lower temperature on the application of magnetic fields. After considering various possibilities for an upturn in resistivity, we found that the Kondo scattering is responsible for upturn at low temperature. The simultaneous presence of ferromagnetism and Kondo scattering is explained by spatial variation of nitrogen vacancy defects from the film surface to the Al sandwich layer. Furthermore, magneto-transport properties of the film measured at different temperature exhibits both negative and positive components described by localized magnetic moment model for the spin scattering of carriers and two-band model, respectively. This work provides insight into the novel co-existence of ferromagnetism and Kondo effect in crystalline AlN.

Hole selective nickel oxide as transparent conductive oxide

Transparent conducting oxides (TCOs) are essential for manufacturing perovskite and heterojunction solar cells. Specifically, nickel oxide (NiO) is of interest because it exhibits hole-selective behavior in conjunction with Si. Additionally, the bandgap of about 3.6 eV allows high transmission even at wavelengths below 500 nm. However, NiO is not yet ready for industrial implementation in solar cells. This study guides a simple, industry-compatible way to fabricate transparent conductive NiO thin films by evaporation and postdeposition annealing. The crystallization behavior of NiO is investigated intensively. The lattice parameter of cubic NiO decreases with increasing annealing temperature, probably caused by the loss of oxygen. Resistivity and absorption measurements were done to assess the suitability of NiO as TCO. A minimum resistivity of about 50 Ω cm with a corresponding absorption coefficient of 19 × 103 cm−1 is reached using an annealing temperature of 400 °C. A p-n junction was formed consisting of n-doped Si and p conducting NiO to prove the hole selectivity of NiO.

Flexible, stretchable, waterproof (IPX7) electro-thermal films based on graphite nanoplatelets & polyurethane nanocomposites for wearable heaters

Electrothermal materials have been widely used due to controllable heat energy in our life. With the development of wearable technology, a flexible, safe and waterproof heater with the good ability to endure repeated bending is required in future. In this paper, we have developed a novel wearable heater based on flexible, stretchable graphite nanoplates and polyurethane (GNP/PU) nanocomposite films. Firstly, the GNP/PU thin films with a thickness of 30–200 μm were fabricated in mass production by the method of gap-coating, which can be bent 180° repeatedly, or even knotted for their excellent flexibility, and has a maximum elongation up to 387.8%, due to the homogenous distribution of GNP in PU matrix. By the control on the amount of GNP and the thickness of the film, the minimum resistivity and square resistance of the GNP/PU films can be 80 mΩ·cm and 4 Ω/□, respectively. Through a further flexible structure designing and waterproof electronic packaging process, the fabricated wearable heaters are able to withstand 100,000 180-degrees bending with the resistance changes of only 3.24%, and have a IPX7 waterproof ability to work continuously for 120 min under 1.30 m water. Interestingly, as-prepared bare GNP/PU films have a good resistence to water and salt erosion, with the light 2.1%, 2.4% and 3.1% increasing in electrical resistance, and without obvious change in heating performance, even after the immersion in pure water, 0.5% and 5% salt water and dried completely. Furthermore, the wearable heaters can generate heat uniformly under the safe voltage of 5–24 V to achieve rapid heating and cooling rate of 25 °C/min and 13 °C/min, respectively. Lastly, a heating full-body vest mode of as-prepared wearable heaters was fabricated, which can work well with hand raising, bending and walking. The results showed that as-prepared wearable heaters were very suitable for wearable electronics, due to the excellent flexibility and stretchability of GNP/PU films and their special packaging structure, which provides a new choice for wearable heating products.

Resistivity Minimum in Beryllium Films

In the analysis of the resistivity of metals, the classical Boltzmann transport equation fails in the condition that the thermal phonon wavelength is larger than the electron mean free path (called the non‐Boltzmann transport regime), and a quantum kinetic equation must be solved. In such a case, the interference between electron−phonon and electron−impurity scattering (electron−phonon−impurity interference effect) should be considered. Herein, the electrical transport properties of Be films grown via direct current magnetron sputtering are studied. Due to the high Debye temperatures and high impurity/defect concentrations of the Be films, the thermal phonon wavelength is larger than the electron mean free path, indicating the non‐Boltzmann transport. The significant resistivity correction from the electron−phonon−impurity interference effect should be observed in the Be films. In the temperature dependence of the resistivity of the Be films, a resistivity minimum near 90 K is observed. After subtracting the contributions of electron−electron and electron−phonon interactions, the electron−phonon−impurity interference‐contributed resistivity is obtained, which increases with temperature like . The signature of the resistivity contribution from electron−phonon−impurity interference effect is observed in the non‐Boltzmann transport regime.

Twofold symmetry of c-axis resistivity in topological kagome superconductor CsV3Sb5 with in-plane rotating magnetic field

In transition metal compounds, due to the interplay of charge, spin, lattice and orbital degrees of freedom, many intertwined orders exist with close energies. One of the commonly observed states is the so-called nematic electron state, which breaks the in-plane rotational symmetry. This nematic state appears in cuprates, iron-based superconductor, etc. Nematicity may coexist, affect, cooperate or compete with other orders. Here we show the anisotropic in-plane electronic state and superconductivity in a recently discovered kagome metal CsV3Sb5 by measuring c-axis resistivity with the in-plane rotation of magnetic field. We observe a twofold symmetry of superconductivity in the superconducting state and a unique in-plane nematic electronic state in normal state when rotating the in-plane magnetic field. Interestingly these two orders are orthogonal to each other in terms of the field direction of the minimum resistivity. Our results shed new light in understanding non-trivial physical properties of CsV3Sb5.

Multifunctional Electrically Conductive Copper Electroplated Fabrics Sensitizes by In-Situ Deposition of Copper and Silver Nanoparticles.

In this study, we developed multifunctional and durable textile sensors. The fabrics were coated with metal in two steps. At first, pretreatment of fabric was performed, and then copper and silver particles were coated by the chemical reduction method. Hence, the absorbance/adherence of metal was confirmed by the deposition of particles on microfibers. The particles filled the micro spaces between the fibers and made the continuous network to facilitate the electrical conduction. Secondly, further electroplating of the metal was performed to make the compact layer on the particle- coated fabric. The fabrics were analyzed against electrical resistivity and electromagnetic shielding over the frequency range of 200 MHz to 1500 MHz. The presence of metal coating was confirmed from the surface microstructure of coated fabric samples examined by scanning electron microscopy, EDS, and XRD tests. For optimized plating parameters, the minimum surface resistivity of 67 Ω, EMI shielding of 66 dB and Ohmic heating of 118 °C at 10 V was observed. It was found that EMI SH was increased with an increase in the deposition rate of the metal. Furthermore, towards the end, the durability of conductive textiles was observed against severe washing. It was observed that even after severe washing there was an insignificant increase in electrical resistivity and good retention of the metal coating, as was also proven with SEM images.

Preparation and application of water-based nano-silver conductive ink in paper-based 3D printing

PurposeIn flexible electronics applications, organic inks are mostly used for inkjet printing. Three-dimensional (3 D) printing technology has the advantages of low cost, high speed and good precision in modern electronic printing. The purpose of this study is to solve the high cost of traditional printing and the pollution emissions of organic ink. It is necessary to develop a water-based conductive ink that is easily degradable and can be 3 D printed. A nano-silver ink printed circuit pattern with high precision, high conductivity and good mechanical properties is a promising strategy.Design/methodology/approachThe researched nano-silver conductive ink is mainly composed of silver nanoparticles and resin. The effect of adding methyl cellulose on the ink was also explored. A simple 3 D circuit pattern was printed on photographic paper. The line width, line length, line thickness and conductivity of the printed circuit were tested. The influence of sintering temperature and sintering time on pattern resistivity was studied. The relationship between circuit pattern bending performance and electrical conductivity is analyzed.FindingsThe experimental results show that the ink has the characteristics of low silver content and good environmental protection effect. The printing feasibility of 3 D printing circuit patterns on paper substrates was confirmed. The best printing temperature is 160°C–180°C, and the best sintering time is 30 min. The circuit pattern can be folded 120°, and the cycle is folded more than 60 times. The minimum resistivity of the circuit pattern is 6.07 µΩ·cm. Methyl cellulose can control the viscosity of the ink. The mechanical properties of the pattern have been improved. The printing method of 3 D printing can significantly reduce the sintering time and temperature of the conductive ink. These findings may provide innovation for the flexible electronics industry and pave the way for alternatives to cost-effective solutions.Originality/valueIn this study, direct ink writing technology was used to print circuit patterns on paper substrates. This process is simple and convenient and can control the thickness of the ink layer. The ink material is nonpolluting to the environment. Nano-silver ink has suitable viscosity and pH value. It can meet the requirements of pneumatic 3 D printers. The method has the characteristics of simple process, fast forming, low cost and high environmental friendliness.

Growth Optimization and Study on Structural, Morphological, Optical and Electrical Properties of As-Deposited Zinc Sulfide Thin Films Fabricated by Radio-Frequency Magnetron Sputtering Technique at Room Temperature

The deposition of Zinc Sulfide (ZnS) thin films is optimized using a radio-frequency (RF) magnetron sputtering technique with variable RF power to minimize deposition steps and lower the fabrication costs. Room temperature as-deposited film growth optimization is conducted by studying their structural, morphological, optical, and electrical properties. The target power and deposition rate were related by a slope of 0.1648 and a linear correlation coefficient (R) of 0.9893. Only one significant peak for the films in the XRD pattern indicated that the films are of a single crystalline structure. All the deposited thin films exhibited a ZB structure. It is observed that the micro-strain ranged from 36.00x10-3 to 4.14x10-3, and that of dislocation density ranged from 6.68 to 0.08 Line/cm2. The optical energy band gaps of as-deposited ZnS films at different deposition power were found from 3.31 to 3.37 eV. The average transmittance percentage was increasing from 71.63% to 84.29%, above 400 nm wavelength. The films exhibited n-type conductivity with bulk carrier density in the order of 1012 cm-3. The carrier concentration and mobility ranged from 2.84x1011 to 3.98x1012 cm-3 and 1.06 to 27.68 cm2/Vs, respectively. The minimum and maximum resistivity of 1.01x104 and 2.52´105 Ω-cm were noted for the film deposited at 90 and 60W power, respectively.

Optimization of Tunnel‐Junction for Perovskite/Tunnel Oxide Passivated Contact (TOPCon) Tandem Solar Cells

A systematic study of the formation of the tunnel‐junction for perovskite/TOPCon tandem solar cells is presented, which consists of a B‐doped poly‐Si (p+‐poly‐Si) and P‐doped poly‐Si (n+‐poly‐Si) double‐layer structure. The rear emitter double‐side TOPCon solar cell is selected as the bottom cell in tandem solar cells, where a p+‐poly‐Si/SiOx forms the rear emitter and an n+‐poly‐Si/SiOx forms the front field with the poly‐Si layer deposited by plasma‐enhanced vapor deposition (PECVD) and crystallized in a furnace. The tunnel‐junction is formed by depositing an additional B‐doped a‐Si:H (p+‐a‐Si:H) on the front n+‐poly‐Si and following a rapid thermal anneal (RTA) to partially crystallize the p+‐a‐Si:H with minimized interdiffusion of B and P. The tunnel‐junction is systematically optimized and it is found that the RTA process at 700 °C produces the optimized tunnel‐junction with the minimal contact resistivity of ≈16 mΩ cm2. The tunnel‐junction formation affects the passivation of the front field TOPCon, but the losses in the passivation quality can be recovered by a forming gas annealing. This process provides a simple and useful method for making the tunnel‐junction in perovskite/TOPCon tandem solar cells.

Improved electrical and optical properties in epitaxial Cd2SnO4 films

AbstractEpitaxial Cd2SnO4 films were fabricated on MgO(00l) single crystalline substrates by pulsed laser deposition technique at various substrate temperatures and growth oxygen pressures. The microstructure, transport, and optical properties of the films were studied in detail. High‐resolution X‐ray diffraction and high‐resolution transmission electron microscopy results demonstrate that all the Cd2SnO4 films are grown epitaxially on MgO(00l) substrates. Atomic force microscope images indicate that the films have smooth surface morphologies. Hall‐effect measurements reveal that the epitaxial film grown at 680°C and 40 Pa presents the minimum resistivity value of 0.61 mΩcm and maximal Hall mobility of 32.87 cm2 V−1 s−1. The metal–semiconductor transitions of Cd2SnO4 films were observed and explained by competitive effects of two conductive mechanisms. The optical transmittance of the Cd2SnO4 films is higher than 75% in the visible and near‐infrared range, and the optical bandgap was determined to be about 3.09 eV for the film grown at optimal condition. The band structure and density of states of the Cd2SnO4 were calculated by the density functional theory.

Effect of low-energy ion assistance on the properties of sputtered ZrB2 films

Zirconium diboride (ZrB2) films have been deposited by direct current magnetron sputtering (DCMS) from a ZrB2 compound target on Al2O3 (0001) substrates held at 600, 700, 800, and 900 °C, and with two different axial magnetic field strengths, 34 and 104 G, generated using a coil surrounding the substrate. Plasma probe measurements show an increase of the ion fluxes on floating-potential substrates of the two different configurations by a factor of 2.8 for 104 G compared to 34 G, while the ion energy remained relatively constant at ≈12 eV. Time-of-flight elastic recoil detection analysis (ToF-ERDA) show that films deposited with a magnetic field of 34 G are highly overstoichiometric with B/Zr ratios ≈2.4, while films deposited with 104 G exhibit a B/Zr ratios ≈2.1. The levels of oxygen and carbon in the films are below 1 at. % irrespective of growth conditions. X-ray diffraction (XRD) θ/2θ scans, complemented by pole figure measurements, reveal that all deposited films are 0001-oriented. XRD θ/2θ scans of the 000ℓ peak intensities and ω (rocking-curve) widths show increased ZrB2 crystal quality with increasing temperature for both magnetic field strengths. Minimum electrical resistivity of ≈100 μΩcm is achieved for an axial magnetic field of 104 G, independent of temperature.

Dense ternary-size particles interstitial filling gradation stacking model for preparing high-quality indium tin oxide targets

A novel ternary-size particles interstitial filling gradation stacking model has been proposed and discussed systematically for preparing dense indium tin oxide (ITO) targets with high density and low resistivity. In this stacking model, three particle sizes satisfy a ratio of 1 :2-1 :62-1. Significantly, the target sintered at 1550 ℃ for 10 h shows maximum relative density of 99.67% and minimum resistivity of 0.79 × 10-4 Ω·cm. Moreover, two new binary-size particles interstitial filling stacking models are proposed and discussed. In binary-size particles models, designed particle sizes satisfy the formulas of d = (62-1)×D and d=(2-1)×D, respectively. These excellent properties are caused by the compact structure. The small particles are filled in the internal gaps between larger particles. 64&118&285 nm ternary-size particles model obviously increases density and decreases resistivity of target. This novel strategy contributes to preparing high-performance target, promoting the development of next generation ITO functional materials.