We reported here the structural, optical, and magnetic properties of Zn_1−xCo_xO nanorods (NRs) with x = 0.00, 0.025, 0.05, and 0.30 wt%. The Zn_1−xCo_xO NRs samples were fabricated by electrochemical deposition and given the symbols S0, S1, S2, and S3 for x = 0.00, 0.025, 0.05, and 0.30 wt%, respectively. It is found that all NR samples were grown along the (002) plane and have a hexagonal structure. As the Co level increases up to 0.30 wt%, the crystallite size and the texture coefficient are respectively decreased from 57 nm to 0.98 to 25 nm and 0.70. While the diameter of NRs increased from 347 to 1730 nm. Interestingly, the weight% (wt %) of O was increased with increasing Co level. The optical band gap (E_g) was found to be 3.32 eV for the undoped ZnO NRs (S0) and reduced to 2.24 eV with more increase of Co up to 0.30 wt%. At 300 K, the So and S1 exhibit diamagnetic behavior over the field range. For S2, such behavior became weakly ferromagnetic at H ≤ 2000 Oe and diamagnetic at H > 2000 Oe. In contrast, the S3 exhibits strong ferromagnetic behavior of magnetization (M) = 0.14 emu/g at 20 kOe. However, with decreasing temperature to 10 K, the paramagnetic behavior is dominant for all NRs. However, all NRs samples revealed a hysteresis loop After subtracting the paramagnetic and diamagnetic contributions from the M-H curves. The S2 showed the highest value for coercive field of 256 and 263 Oe, as compared to the other NRs (15–65 Oe). Although S3 shows the softest magnetic properties among all samples (with coercive fields of 15–27 Oe), it exhibits the strongest ferromagnetic behavior. The Zfc/Fc measurements show that all the samples are paramagnetic by nature with no sign for blocking temperature of magnetic nanoparticles. Furthermore, the residual magnetization values measured at 300 K (from both FC and ZFC curves) show a general increasing trend with cobalt doping concentration, with measured values of 6.45 × 10⁻⁹, 2.13 × 10⁻⁴, 8.71 × 10⁻⁵, and 6.45 × 10⁻² emu/g for samples S0 through S3, respectively. This work provides new insights into the correlation between electrochemical growth conditions, defect chemistry, and room-temperature ferromagnetism in Co-doped ZnO systems, advancing beyond previous reports through its demonstration of bandgap tuning and robust ferromagnetism in electrochemically grown NRs and temperature-dependent magnetic phase transitions directly correlated with structural parameters.

This paper is aimed at proposing a novel method for calculating the resistance-to-ground of three grounding-schemes under known applied-voltage. The schemes include a vertical rod(s), and square/rectangular grids with and without rods. The schemes are buried in a homogenous-soil or two-layer soil with an interface-plane separating the soil layers. The calculation method is based on the current-sphere-simulation-technique (CSST) along with the concept of images. The currents in the vertical-rod and the grid-conductors are simulated by current- spheres of diameters the same as the rod or conductor. The interface-plane between soil-layers is simulated by two sets of equal number of current-spheres. Satisfaction of Dirichlet boundary-condition at the scheme-surface and normal current-density continuity along with the potential-equality boundary-conditions the interfaceplane formulates a set of equations, whose solution determines the currents of the simulation-spheres. The sum of sphere-currents simulating the ground-scheme represents the current injected into the surrounding-soil for evaluating the scheme groundingresistance. The calculated grounding-resistance by the proposedmethod agreed with those obtained from COMSOL and CYMGRD with a deviation up to 13.2% for the investigated three groundingschemes.

The charge simulation method (CSM) was first introduced for field calculation in high-voltage (HV) arrangements involving electrodes and two dielectrics at most. Each electrode is simulated by a set of charges inside it. The interface between the two dielectrics is simulated by two sets of charges, one set in each dielectric. The proposed method aims to extend the CSM for the first time to apply to arrangements with many electrodes and multi-dielectric layers. This represents the novelty of the method. Its intelligence lies in the proper selection of the simulation charges to be used for calculating the electric potential and field anywhere within the HV arrangement, following a systematic procedure. The method predicts potential and field values that coincide with their respective exact values in a single-core cable with multi coaxial-dielectric layers. For a dielectric-barrier discharge (DBD) arrangement having multi parallel-flat-dielectric layers with and without embedded electrodes, the method also predicts potential and field values that agree reasonably with those obtained using COMSOL software. The effectiveness of the embedded electrode in decreasing the field at the edge of the stressed electrode is verified by the proposed method in agreement with the experimental observations recorded for the investigated DBD arrangement.

This paper introduces a new design of a grounding grid composed of multi-concentric rings (MCRG) tied together by conductors and provided with rods uniformly distributed around the periphery of the outer ring. The methodology for evaluating ground resistance and ground surface potential for predicting the step and touch voltages is based on the current simulation technique. Current spheres simulate the grid components of rings, conductors, and rods, the number of which is well-defined. In a two-layer soil, the interface plane between the layers is simulated by two sets of an equal number of current spheres. Satisfaction of pertinent boundary conditions at the surface of grid components and interface plane formulates a set of equations, whose solution determines the current values of the simulation spheres. With known sphere currents simulating the grid, the ground resistance and the distribution of ground surface potential are evaluated. The proposed MCRG outperforms square and rectangular grid designs reported in the literature, being safer with lower step, touch voltages, and ground resistance for the same grid area and fault current.