DC Resistivity Studies Research Articles

Structure, DC electrical resistivity, and magnetic properties of Gd3+ substituted NiZnCo ferrites system

Gd3+ substituted NiZnCo ferrite materials with the chemical formula Ni0.4Zn0.35Co0.25Fe2–xGdxO4 (x = 0.0, 0.02, 0.04, 0.06, 0.08 and 0.1) were synthesized with the solid-state approach. We have concentrated more on the impact of ferrite synthesis on crystal structure, microstructure, and magnetoelectric characteristics. XRD shows the pure cubic spinel structure. Images taken with a SEM microscope supported the formation of nanoparticles. The sample’s spinel structures were again validated with FTIR, confirming the existence of their functional group. Prepared samples' saturation magnetization, remanence, and coercivity were calculated using VSM data, which decreased with Gd3+ substitution. The metal-to-semiconductor transition was seen within the sample’s DC resistivity study with respect to temperature.

Effect of La3+ ion doped Co-Zn nano ferrites: Structural, optical, electrical and magnetic properties

Lanthanum substituted Co Zn Fe 2 O 4 fabricated nano ferrite powder was conformed single phase cubic spinal structure from the XRD and particle size conformed by the TEM. Optical and electric properties was studied. VSM was used to investigate magnetic characteristics from room temperature. • Effect of La 3+ ion doped Co-Zn nanoferrites were synthesised through the citrate gel auto-combustion method. • Rietveld refinement was used to analyse XRD data and confirmed the nano-range particles with spinel ferrites. • FE-SEM, EDAX, FTIR, TEM, AFM, FTIR, DC electrical resistivity, dielectric studies, and VSM studies are conducted. Lanthanum ion doped with large percentages of zinc cobalt ferrite (Co 0.1 Zn 0.9 La x Fe 2-x O 4 ) nanoparticles with an ‘x’ range of from 0.000 to 0.030 (with the step of x=0.005) were manufactured through the citrate gel auto-combustion method. The fabricated synthesised powder was analysed to find out the structural characterization from the XRD, FE-SEM, EDAX, TEM, FTIR, and AFM. The average crystallite size was confirmed and nanometer ranges were exposed from the XRD and TEM images, which ranged between 10 nm and 15 nm and the FCC spinel structure. The lattice parameter is found to increase from 8.392 A o to 8.452 A o with the substitution of La 3+ ion, and a monotone diffraction peak (311) shows towards minor angles of degrees (35.33° to 35.13°). The surface area increases from 122.8 to 186.3 m 2 g -1 with the addition of La 3+ ion. From FTIR the bond lenth (ν 1 ) ranges from 512 cm −1 to 530 cm −1 , increasing with doped La 3+ ion content. In the AFM analysis, the surface roughness decreases from 10 nm to 6.5 nm. The prepared samples the results of magnetic, temperature variation of dielectric, and DC resistivity studies were discussed. The dielectric constant reduces dramatically as the substituted lanthanum ion concentration rises with temperature, although it remains stable in the three previously described ranges. DC resistivity, curie temperature, and drift mobility have an inverse relationship with temperature increase. The magnetic properties of hysteresis loops indicate a shift from harder to softer magnetic moments. The Ms and Mr decrease as the lanthanum ion concentration in Co-Zn ferrite increases, from 15.19 emu/g to 9.30 emu/g, and from 3.81 emu/g to 2.33 emu/g and the magnetic moment decreases from 0.6539 to 0.4045. The prepared nano ferrite particles were suited as magnetic adsorbents in the departure of impurities from waste water.

Correlation between the Magnetic and DC resistivity studies of Cu substituted Ni and Zn in Ni-Zn ferrites

Cu substituted Ni0.5-xCuxZn0.5Fe2O4 (x = 0, 0.05, 0.1, 0.15 and 0.2) samples is synthesized using the sol-gel auto-combustion process. They have a cubic spinel structure with crystallite size in the range of 29.01–42.68 nm. The increment in the copper content increases the DC conductivity. The electrical resistivity decrease with an increase in the temperature i.e. it has a negative temperature coefficient with resistance similar to semiconductors. The remnant ratios R obtained from VSM show their isotropic nature forming single domain ferrimagnetic particles. The results are compared with Ni0.5CuxZn0.5-xFe2O4 (x = 0 to 0.25). The resultant material Cu substituted Zn is more significant than that of Ni as indicated by its results and previous literature. BIBECHANA 19 (2022) 61-67

Impact of La3+ substitution on electrical, magnetic, dielectric and optical properties of Ni0.7Cu0.1Zn0.2LaxFe2–xO4 (0

The oxalate co-precipitation method was used to synthesize the La3+ substituted Ni–Cu–Zn (La–NCZ) nanoferrites having chemical composition Ni0.7Cu0.1Zn0.2LaxFe2–xO4 (x = 0, 0.015, 0.025 and 0.035). DC resistivity study of nanoferrites shows both the conducting and semiconducting behaviour. The room temperature DC electrical resistivity of Ni–Cu–Zn (NCZ) nanoferrites decreases, whereas Curie temperature increases with increasing La3+ content. In the temperature range of 30–170 °C nanoferrites show p-type semiconducting behavior except x = 0.015; thereafter, they show n-type behaviour. The frequency dispersive initial permeability (μi) associated with its real and imaginary (μ′ and μ") parts are attributed to the domain wall movement and magnetic spin resonant. The μi, μ′ and μ" of La–NCZ nanoferrites are higher than those of pure NCZ nanoferrite. Dielectric constant (ε′), dielectric loss (ε″) and AC resistivity (ρAC) of La–NCZ nanoferrites show normal dielectric behaviour. It is found that ε′ of NCZ nanoferrites decreases with the increasing content of La3+ ions. The bandgap energy of La–NCZ nanoferrites is achieved in the range 1.36–1.70 eV confirming the semiconducting nature of materials.

Electrical and Dielectric Studies of the Cd‐Doped Co‐Ni Ferrites Synthesized by Solid State Reaction Method

AbstractThe present study reports the dielectric and DC resistivity studies of the Cd doped Co‐Ni ferrites synthesized by solid state reaction method. The XRD studies confirm the cubic spinel structure of the samples. The substitution of the cadmium in the ferrite system significantly influences the AC conductivity, involvement of the grain boundary involvement in conduction. The variations of dielectric constant and dielectric loss for all the samples are studied as a function of frequency and show an increase with doping concentration. The DC resistivity studies confirm the semiconducting nature of the synthesized ferrites. The activation energy is observed to be in the range of (0.534–0.629 eV).

Structural and electrical properties of copper ferrite (CuFe2O4) NPs

Spinel ferrites are the important class of soft magnetic material composed of iron oxide and metal oxide as their main compound. Copper ferrite (CuFe2O4) is one such spinel ferrite with great potential technological applications. It is well-known about ‘Jahn-Teller distortion’ that the copper ferro-spinel are at room temperature has a co-operative distortion to the tetragonal site-symmetry which depends only upon the copper ion distribution. The structural and electrical properties of Copper ferrite were investigated by X-ray diffraction and DC-resistivity studies. The room temperature XRD data revealed that the formation of tetragonal structure of (CuFe2O4) NPs. The crystallite size (t) nm was obtained from Debye-Sherrer’s formula indicated that the (CuFe2O4) NPs shows nanocrystalline nature with crystallite size 14 nm. The lattice constant (a) was found to be in the reported range (∼8.380 Ǻ). The DC-resistivity parameters were drawn from the two point probe device. An activation energy AE of the copper ferrite nanoparticles was found to be 0.01 eV.

Bulk magnetization, temperature - Dependent ac susceptibility and dc resistivity study on Mn0.7+xZn0.3SixFe2-2xO4 (x = 0.0–0.3) spinel ferrites

Polycrystalline samples of spinel ferrite series, Mn0.7+x Zn0.3SixFe2-2xO4 (x = 0.0, 0.1, 0.2, 0.3), were characterized by X-ray powder diffractometry, bulk magnetization at 300 K and 80 K, temperature dependence of low field ac susceptibility (χac (T)) (T = 300–525 K) and dc electrical resistivity (ρdc (T)) (T = 300–772 K) measurements. The variation of intrinsic and extrinsic magnetic parameters as a function of Mn–Si concentration (x) has been discussed. It is found that the system possesses a non-collinear spin arrangement and the canting angle increases with x. The Néel temperatures determined experimentally from susceptibility measurement adequately reflected the values calculated theoretically. The χac (T) curves revealed normal ferrimagnetic behavior while ρdc (T) depicts characteristic semiconducting behavior. The activation energy is found to increase with x that can be explained in light of the structural and microstructural parameters.

Dielectric, impedance relaxation and DC resistivity studies on microwave sintered Ba1-xRexTiO3(Re = Nd&Pr) ceramics using 5% SiO2 as sintering aid

ABSTRACTBa1-xRexTiO3 ceramics (Re = Nd&Pr with x = 0.002 & 0.004) were prepared through microwave sintering route using 5% SiO2 as sintering aid. The dielectric, impedance and DC resistivity studies were carried out over a wide range of temperature. From dielectric studies, it is observed that the transition temperature increased with the substitution of rare earth ions. The room temperature dielectric constant for the Nd (x = 0.002) doped barium titanate is higher when compared to other compositions and the value is 13,600.28. Impedance studies revealed relaxation behaviour. In the present study grain, grain boundary and sample-electrode effects were separated out by using Cole-Cole data. From the DC resistivity studies, it is observed that Pr (x = 0.004) doped barium titanate ceramic showed one order of magnitude PTCR effect.

Dielectric relaxor, impedance relaxor, PTCR and electromechanical effects in multifunctional ceramic: [Ba(Nd0.1Ti0.8Nb0.1)O3]0.65[Na0.5Bi0.5TiO3]0.25[BaZrO3]0.10

ABSTRACT[BaNd0.1Ti0.8Nb0.1O3]0.65[Na0.5Bi0.5TiO3]0.25[BaZrO3]0.10 (BNNT-NBT-BZ) ceramic is prepared through solid state sintering method. The dielectric, impedance and DC resistivity studies are carried out as a function of temperature. Dielectric and impedance studies revealed relaxor behaviour. DC resistivity studies revealed PTCR effect in the present ceramic. Capacitance resonance and anti-resonance studies in free and clamped state are carried out over a wide range of frequency at room temperature. The values of Kt, Keff and d33 at room temperature are 0.112, 0.105 and 1.003 pm.V−1 respectively for ceramic sample studied under free state, whereas for the samples studied under clamped state the values are 0.667, 0.629 and 26.410 pm.V−1 respectively. Stress and temperature induced modulus resonance and anti-resonance studies are carried out over a wide frequency range and temperature. The values of Kt, Keff and d33 at 723K are 0.99926, 0.99911 and 14.188 nm.V−1 respectively.

Impedance and DC resistivity studies on chromium substituted cobalt ferrite

Nanocrystalline chromium substituted cobalt ferrite has been prepared by the sol–gel method. XRD analysis reveals that the samples crystallize to cubic symmetry with $$Fd\stackrel{-}{3}m$$ spacegroup. Two transition temperatures (T D ~450 and T M ~600 K) have been observed from the impedance versus temperature measurement. T D increases with the increase in frequency due to dipole response to the frequency. T M is comparable with the para-ferrimagnetic transition temperature of cobalt ferrite, which is independent of frequency. This result is well supported by the temperature dependent DC resistivity measurement. The modified Debye relaxation could explain the impedance spectra of CoFe2−xCrxO4. The grain and grain boundary effect on impedance spectroscopy has been observed from Cole–Cole analysis. The ac conductivity follows Arrhenius behavior at different frequencies. All the samples exhibit the negative temperature coefficient of resistance behavior which reveals the semiconducting behavior of the material. The Mott VRH model could explain the DC electrical resistivity. Both ac impedance and DC resistivity are well co-related with each other to explain the electron transport properties in Cr substituted cobalt ferrite. The electrical transport properties could be explained by the electron hopping between different metal ions via oxygen in the material.

DC Resistivity Studies of Shallow Geology in the Vicinity of Vistula River Flood Bank in Czernichów Village (Near Kraków in Poland)

Abstract DC resistivity methods, soundings and Electrical Resistivity Tomography, were applied to study shallow geology in the place of planned construction of an experimental flood bank. The geoelectrical surveys provided quantitative information about the spatial presence of the various geoelectrical/geological layers: alluvial soils, sands, gravels and clays. ERT allowed maps to be constructed showing subsurface structure. A combination of geoelectrical and geological information resulted in a much better identification of the geological structure.

High-pressure study of transport properties in Co0.33NbS2

This is the first study of the effect of pressure on transition metal dichalcogenides (TMDs) intercalated by atoms that order magnetically. Co${}_{0.33}$NbS${}_{2}$ is a layered system where the intercalated Co atoms order antiferromagnetically at ${T}_{N}$ = 26 K at ambient pressure. We have conducted a detailed study of dc-resistivity ($\ensuremath{\rho}$), thermoelectric power ($S$), and thermal conductivity ($\ensuremath{\kappa}$). At ambient pressure the magnetic transition corresponds to a well-pronounced peak in $dS/dT$, as well as to a kink in the dc-resistivity. The effect of ordering on the thermal conductivity is rather small but, surprisingly, more pronounced in the lattice contribution than in the electronic contribution to $\ensuremath{\kappa}$. Under pressure the resistivity increases in the high-temperature range, contrary to all previous measurements in other layered TMDs. In the low-temperature range the strong dependences of thermopower and resistivity on pressure are observed below ${T}_{N}$, which, in turn, also depends on pressure at rate of $d{T}_{N}/dp$ \ensuremath{\sim} \ensuremath{-}1 K/kbar. Several possible microscopic explanations of the reduction of the ordering temperature and the evolution of the transport properties with pressure are discussed.

Growth and characterization of molybdenum oxide nanorods by RF magnetron sputtering and subsequent annealing

High-densely packed and uniformly distributed molybdenum oxide nanorods have been grown onto glass substrates by RF magnetron sputtering and subsequent annealing in an oxygen atmosphere. A two-step growth mechanism (sputtering redeposition and enhanced rearrangement during annealing) for the formation of MoO3 nanorods has been proposed. The morphological, structural, optical and electrical properties of the nanorods have been investigated systematically using atomic force microscopy, scanning electron microscopy, x-ray diffraction, micro-Raman, UV–visible, photoluminescence (PL) spectroscopy and dc resistivity studies. The nanorods in the as-sputtered film and the film annealed at 473 K are amorphous in nature. However, the nanorods in the films annealed at 573 and 673 K exhibit the presence of monoclinic Mo8O23 and orthorhombic MoO3, respectively. Vibrational analysis of the molybdenum and oxygen atoms in the nanorods is carried out by micro-Raman spectra. The nanorods show room temperature PL in the UV–visible region. The PL emission is found to be strongly enhanced by post-deposition annealing. The low temperature resistivity measurement is done on the as-deposited film; the activation energy and polaron hopping energy for electrical conduction are calculated. The MoO3 nanorods are expected to exhibit enhanced functionality, particularly in nanoscale, photochromic and gas sensing applications.

Retrieval of Mercury from Wastewater as Stable Mercury Ferrite

Abstract Mercury contamination in water and wastewater is a global risk and health problem. So there is a concrete need for an eco-friendly process that can remove the toxic mercury ions as well as convert the mercury to a value added product. The black ferruginous mercury ferrite (FMF) as a value added product was synthesized by coprecipitation technique at 50°C. X-ray diffraction studies conducted on FMF obtained using CuKα1 radiation revealed that this crystalline compound has an orthorhombic symmetry. The method described in this study removed mercury ions with greater efficiency compared with the prevalent methods quoted in the literature. The results of thermal analysis of the synthesized compound, on comparison with magnetite (Fe3O4), revealed a shifting of the exothermic peak towards the lower temperature side. This behavior indicates phase transition and sample crystallization. The DC resistivity studies on FMF carried out at various temperatures in the range of 27 to 500°C showed that the compound is a semiconductor in nature and shows sharp changes in the resistivity in the temperature range of 342.38 ± 10°C (Tcelect). The recovered FMF could be used in several applications such as semiconductors, at high temperature applications, to minimize eddy current losses, and as adsorbents as well as catalysts for the reduction of exhaust gas emissions.

A Study of DC Resistivity Sounding for Anomalous Bodies in Tunnel

The resistivity sounding data can be carried out on four corners and four walls in tunnel. But it is difficult to interpret the sounding data because of the influence of tunnel itself and volume-effect. We performed modelling of DC resistivity sounding in tunnel using FEM. Firstly, the value of normal potential in tunnel is presented. Then, numerical modelling of resistivity sounding in tunnel is done with the anomalous potential method of FEM. The result shows that when the size and the depth of bodies, and spacing of electrodes are different from the size of cross section of tunnel not too much, the section profiles of sounding on walls of tunnel mainly reflect the geologic bodies beside the walls and don't reflect the bodies obviously on other positions. The crosss section of sounding on corners of tunnel will reflect the bodies beside two adjacent walls synthetically.

Monitoring Yearly Changes and Their Influence on Electrical Properties of the Shallow Subsurface at Two Sites Near the Rio Grande, West Texas

We present the results of a case study that monitored changes in the electrical properties of soils on a bi-monthly basis between August 1999 and November 2000 at two sites located along the banks of the Rio Grande, west Texas. One site was located within an abandoned channel of the Rio Grande and showed relatively homogeneous layering, while the second site exhibited complex interfingerings of crevasse splay (sands and silts) and floodplain muds. Repeated EM-31 ground conductivity measurements at both sites showed that conductivities within the upper [Formula: see text] of soil could change by up to a factor of 2 within a year’s time. DC resistivity studies suggested up to a factor of 5 change in resistivity values within the upper [Formula: see text] of soil. These changes appear to be related to remobilization of salt in the soil following rainfall or irrigation events. These dramatic fluctuations make it difficult to image deeper ([Formula: see text] depth) conductivity changes in the subsurface.

Diffuse phase transition in Ba 5YTi 3− xZr xNb 7O 30 ferroelectrics

The polycrystalline samples of Ba 5YTi 3− x Zr x Nb 7O 30 ( x=0,1,2,3) complex tungsten–bronze-type compounds were prepared by a high-temperature solid-state reaction technique. Room temperature preliminary X-ray diffraction (XRD) studies suggest the formation of single-phase compounds with an orthorhombic structure. Detailed studies of dielectric constant ( ε) and tangent loss (tan δ) of the above compounds as a function of frequency (200 Hz–1 MHz) at room temperature, and also as a function of temperature (liquid nitrogen to 350 °C) at different frequencies (1, 10, 10, 100 kHz and 1 MHz) show that the above compounds have diffuse ferroelectric phase transition with relaxor properties. Transition temperature ( T c) of the materials decreases with increase in diffusivity ( γ) for higher concentration of Zr. Study of dc resistivity has been carried out from room temperature to 400 °C.

Structural and dc electrical resistivity study of Gd 3+-substituted Cu-Cd mixed ferrites

Polycrystalline ferrite compositions of Cd x Cu 1- x Fe 2- y Gd y O 4 ( x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0; y = 0.0 and 0.1) were prepared by the standard ceramic technique. The X-ray crystallographic study was done using filtered Cu K α radiation. From the diffractograms it is observed that for x ⩾ 0.2 compounds are cubic spinels, while for x = 0 they are tetragonal, and the dependence of the lattice constant on cadmium concentration obeys Vegard's law. The infrared absorption of the powder samples shows two strong absorption bands in the frequency range 400–600 cm -1, and the analysis shows that Gd occupies ‘B’ sites. The chemical analysis was done by atomic absorption spectroscopy. The dc resistivity study shows an increase in Δ E values and thus in the resistivity after Gd 3+ substitution, suggesting that even though Gd 3+ occupies ‘B’ sites it does not take part in the conduction mechanism, but impedes it.

Influence of alkali-rare earth ions on the synthesis dielectric and ferroelectric properties of BaTiO3ceramics

Abstract Solid solutions of Li0.05Ba0.9Nd0.05TiO3:Li0.05Ba0.8625Nd0.045TiO3:Li0.05Ba0.825Nd0.1TiO3:Li0.05Ba0.7875Nd0.125TiO3, K0.1Ba0.95TiO3, K0.1Ba0.8Nd0.1TiO3, K0.1Ba0.725Nd0.15TiO3 and K0.1Ba0.65Nd0.2TiO3 have been prepared by the usual sintering technique. The dielectric constant was studied versus temperature at 1 KHz in the temperature range 5 to 180°C. Substitution of Nd3+ in BaTiO3 decreases the Curie temperature and the dielectric constant too. Curie constant is calculated in all the compositions. DC resistivity studies have been made in the Li+ doped compositions.