Complex Impedance Plane Research Articles

A Mobius transformation-based liftoff effect reduction method for crack classification and prediction in eddy current testing

In eddy current (EC) defect evaluation, accurate determination of the crack depth is crucial. The lift-off signal on the complex impedance plane is not necessarily horizontal and mostly arc-shaped, which makes it difficult to separate from crack signals, which can have various orientations depending on probe characteristics and frequencies. Phase rotation is normally used to align the lift-off signal to the real axis and defect signal is read from the imaginary axis. However, this approach proves challenging to separate lift-off and defect signals within the complex plane in many cases.To address this issue, this study proposes and implements a Mobius transformation that linearizes the arc-shaped lift-off signals on the complex plane, enabling more accurate extraction of crack signals unaffected by lift-off signal height. Furthermore, it is demonstrated through k-nearest neighbors (kNN) that the transformed crack signals can still be effectively quantified.

Effect of seasonal variation in dielectric properties of groundwater from Vadodara region

Groundwater samples were collected during different months from the same site from Vadodara district of Gujarat state. The complex permittivity of the water samples were precisely determined over the frequency span 20 Hz to 2 MHz. Complex permittivity spectral data were converted into complex impedance formalism. Obtained results were analysed to get information of seasonal variation in groundwater quality. Dielectric constant for all samples is found to decrease linearly and rapidly with increase in frequency up to about 4 kHz, after which it decreases slowly and achieves static value approximately 78, near 2 MHz for all water samples. Dielectric loss for the water sample collected in monsoon season (August) is the highest, which shows the presence of ions dissolved from the soil in rain water. DC resistance values, determined from the complex impedance plane plot (Z′’ vs. Z″), suggested an increase in the conductivity of the water samples collected near the end of monsoon season, due to the dissolved minerals and salts from soil. The calculated values of ε′’/ε′’ DW and ε″/ε″DW ratio for the water sample of August’18 show a relatively large increase during the post-monsoon month of August’18, above 2 kHz, as compared to other months.

Fractional model of the chemical inductor

A multitude of materials and processes of a different nature frequently exhibit, in addition to the classical capacitive arcs, inductive loops in the complex impedance plane. It is a stable and physically robust response originated, from a mathematical perspective, by the introduction of a capacitive coupling in the slow relaxation variable. Nevertheless, the dynamical behavior of such systems shows, in reality, pronounced experimental deviations from the ideal inductive behavior. For this reason, the scientific community in general claims for the development of a novel theory that helps to phenomenologically interpret this pattern change, also encompassing the associated inherent physical complexity that capitalizes on the vast majority of real-world processes. Here, we present a generalization of the classical fast-slow models to naturally explain the anomalous dynamics observed experimentally in different types of measurement techniques, such as the inductance dispersion in impedance, the fractional relaxation processes with negative spike components in the transient responses, and the inverted current-voltage hysteresis. From numerical simulations, we analyze in detail the crossover dynamics from capacitive to inductive properties from the perspective of the constant phase element. Our work devises a useful theoretical framework that explains, in frequency and time domain, the coexistence of dispersive features and the transformation of the electrical behavior in terms of an anomalous bifractional crossover. Finally, we show the dominant role of the fractional-order dynamics in the appearance of inverted hysteresis commonly found in current-voltage curves. Although in literature, everything looks, in a certain manner, simple, the reality is that many real-world materials exhibit an intricate and complex nature that leads to anomalous processes evidenced by dispersive dynamics observed through different measurement techniques. This change of pattern analyzed here is appealing as a mathematical tool to interpret the physical phenomena of many familiar systems.

Investigation on electrical transport and dielectric relaxation mechanism in TbCrO3 perovskite orthochromite

Herein, the TbCrO3 (TCO) chromite was synthesized by the sol-gel auto-combustion route and sintered at 900 °C. The Rietveld analysis of the room temperature powder X-ray diffraction profile confirmed the single-phase formation of the material crystallized in the orthorhombic phase of the perovskite structure with Pbnm space group symmetry. The surface morphology, the elemental composition, and the chemical states of the compound were investigated by field emission scanning electron microscopy, energy dispersive X-ray analysis, and X-ray photoelectron spectroscopy, respectively. The electronic density of states, band structure, and electron density were analyzed by Density Functional Theory. The electrical transport and dielectric relaxation mechanism were investigated using complex impedance spectroscopy over the experimental frequency and temperature ranging from 40-1.2x106Hz and 138−273 K, respectively. Two semicircular arcs in the impedance complex plane plots were modeled to an equivalent circuit configured by RG∥QG+RGB∥QGB which were attributed to the contributions of the highly resistive grain boundaries and relatively conducting grains in the material. The electrical conductivity as a function of frequency followed Jonscher’s universal power law behavior and an increasing nature of the temperature-dependent frequency exponent suggested small polaron hopping as the electrical conduction mechanism of the material. The least capacitive response of the TCO system was investigated by the complex electrical modulus formalism and the frequency-dependent imaginary modulus spectra were modeled by the Kohlrausch–Williams–Watts function, which resolved the thermally activated peaks of bulk and interface effects to the dielectric relaxation mechanism. The dielectric constant exhibited Maxwell-Wagner interfacial polarization effects and the dielectric loss factor showed frequency dispersion at all temperatures.

Graphene quantum dots (GQDs) decorated Co-Zn ferrite: Structural, morphological, dielectric, and magnetic properties

GQDs/Co0.5Zn0.5Fe2O4 nanocomposite was synthesized using a facile sonication-assisted approach. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), elemental dispersive X-ray spectroscopy (EDX), impedance analyzer and vibrating sample magnetometer (VSM) were employed to characterize the synthesized samples. The XRD data confirmed the formation of GQDs, Co-Zn ferrite and GQDs/Co-Zn ferrite nanocomposite with no detectable impurity peaks. FTIR results identified the presence of GQDs in GQDs/Co-Zn ferrite nanocomposite. The morphological study revealed the decoration of spherical GQDs on the surface of Co-Zn ferrite. Complex impedance plane plots showed the contribution of the relaxation phenomenon associated with grain and grain boundaries in observed dielectric properties of the nanocomposite. The inclusion of GQDs led to the enhancement of the dielectric constant of the nanocomposite at low frequencies. GQDs/Co0.5Zn0.5Fe2O4 showed superparamagnetic properties which makes it a potential material to be used as a contrast agent in magnetic resonance imaging (MRI) applications.

Optimal design of broadband acoustic metasurface absorbers

The absorption of low-frequency noise has always been limited by structural thickness, but the novel physical properties of sound-absorbing metamaterials provide a solution to this problem. Based on genetic algorithm, an acoustic metasurface absorber (AMA) composed of micro-perforated plates (MPPs) and impedance matching coiled-up cavities (IMCCs) is proposed. Different from previously reported metamaterials, this structure can easily provide flexible and accurate broadband sound absorption in different target frequency bands. The theoretical model behind the algorithm is established, and two optimal structures (AMA I/AMA II) are obtained for low and mid-high frequency bands. Broadband sound absorption is realized with a thickness of only 71 mm (about 1/13 of the relevant wavelength at 369 Hz), and an average sound absorption coefficient of 0.931 is achieved in the low-frequency band of 350–1000 Hz. Furthermore, by changing the frequency band of the quasi-perfect absorber to 500–2000 Hz, the average sound absorption coefficient exceeds 0.945 with a thickness of only 55 mm (about 1/11 of the relevant wavelength at 563 Hz). The reflection coefficient in the complex plane and theoretical impedance analysis are utilized to reveal the underlying mechanism of the absorption and the acoustic characteristics of the two structures, which show excellent broadband absorption performance in the low and mid-high frequency bands. This work provides a method of arbitrarily modulating surface acoustic impedance in broadband and a reference for broadband noise control.

A strategy to improve dielectric permittivity of Mg–Zn ferrite by using silver nanoparticles

In this work, we used silver nanoparticles (Ag NPs) to enhance the dielectric properties of magnesium-zinc ferrite (Mg–ZnFe2O4) by enhancing local electric field with the creation of nano/micro capacitors between conducting metal particles (Ag NPs) and insulating host (Mg–ZnFe2O4). Mg–ZnFe2O4 was synthesized using the sol-gel method and silver NPs were decorated on magnesium zinc ferrite (Ag@Mg–ZnFe2O4) by employing a sonication approach. The effect of Ag NPs concentration was studied on the structural, morphological, optical, dielectric, and magnetic properties of Ag@Mg–ZnFe2O4 nanocomposite. X-ray diffraction (XRD) confirmed the presence of cubic Mg–ZnFe2O4 and face-centred cubic (FCC) Ag NPs in Ag@Mg–ZnFe2O4 nanocomposite. The structural parameters such as lattice strain, crystallite size and microstrain were correlated with Ag NPs concentration. The morphological study of Ag@Mg–ZnFe2O4 showed uniform decoration of silver at low concentrations; higher concentrations of silver led to reduced covering due to the agglomeration tendency of Ag NPs. Diffused reflectance spectroscopy (DRS) was employed to estimate the effect of Ag NPs on the optical bandgap of Mg–ZnFe2O4. The bandgap narrowing was observed due to the overlapping of the Ag conduction band with the valence band of Mg–ZnFe2O4. All Ag@Mg–ZnFe2O4 samples showed superparamagnetic behaviour and the saturation magnetization was decreased with the increase in the non-magnetic Ag nanoparticles in the nanocomposite. Impedance spectroscopy (IS) was employed to comprehensively analyze the dielectric properties of Ag@Mg–ZnFe2O4. Complex impedance plane plots confirmed the involvement of relaxation phenomena related to grains and grain boundaries in the observed dielectric properties. The decoration of silver nanoparticles was associated with the realization of a high dielectric constant (∼104) in all prepared samples at low frequency. Moreover, uniform decoration of silver was found to show a more stable dielectric constant with relatively low dielectric loss.

Structural, morphological, optical and dielectric properties of sodium bismuth titanate ceramics

• The NBT ceramic was prepared by solid state reaction. • Modified Debye theory has been adopted to describe the phenomenon of relaxation. • The temperature dependence of Dc-conductivity of NBT followed the Mott’s Variable Range Hopping (VRH) law. This work focuses on the structural, optical and electrical properties of sodium bismuth titanate Bi 1/2 Na 1/2 TiO 3 (NBT) lead-free ceramic for its possible application in capacitors, batteries and as an electrolyte in SOFC. NBT material was prepared by the solid-state method. X-ray diffraction analysis performed at room temperature revealed a rhombohedral structure with R3c space group. Rietveld refinement confirmed a good agreement between the calculated and the observed pattern. Scanning electron microscopy analysis revealed a polycrystalline nature of the material with a grain size of 29.17 µm. FT-IR analysis showed the presence of different bonds. The band gap energy was extracted through diffuse reflectance spectroscopy and was found to be 2.61eV. Detailed studies of dielectric and impedance properties carried out in the frequency range of 40–10 7 Hz at different temperatures (from 400K-700K) provided many interesting properties. The dielectric loss and dielectric constant with frequency increase. This behavior could be interpreted by the Maxwell–Wagner type of polarization in agreement with Koop's theory. To explain the complex impedance plane plots, an equivalent circuit template was employed, reflecting semiconducting behavior of NBT. The Ac-conductivity spectrum satisfied Jonscher’s power law below 460K and followed Jonscher’s double power law (DPL) above 480K. The correlated barrier hopping (CBH) and small polaron hopping (SPH) models could explain the conduction mechanism at the studied temperature range. The study of the Dc-electrical conductivity confirmed that NBT followed the variable range hopping (VRH) model. The present work could give further insights into this kind of material from a physical point of view and thus enhance its presence in the industrial field.

Low-frequency Inductive Loop and Its Origin in the Impedance Spectrum of a Graphite Anode

Graphite is a well-known anode material for commercial lithium-ion batteries, and its physical and electrochemical properties have been studied extensively. However, the origin of an inductive loop observed in the low-frequency region of the Nyquist complex plane impedance spectrum of the graphite anode has been widely debated and attributed to contrasting reasons. This paper investigates the impedance spectrum of the graphite anode at various states of charge (SoCs) using three-electrode galvanostatic Electrochemical Impedance Spectroscopy (EIS) and further explores the impedance response of the electrolyte as a function of frequency. The graphite anode EIS measurement displayed an inductive loop in the low-frequency region for almost entire SoCs, irrespective of the solid electrolyte interphase (SEI) age. To study the origin of this inductive loop in the graphite impedance spectrum, we fabricated a three-electrode pouch cell with graphite and NMC electrodes and estimated the electrolyte impedance in the frequency range from 1 MHz to 0.05 Hz. The electrolyte impedance at low frequencies exhibited inductive behavior, indicating a significant role of the electrolyte in the origin of the inductive characteristic in the low-frequency region of the graphite EIS spectrum.

Dielectric response of a hybrid nanofluid containing fullerene C60 and iron oxide nanoparticles

Dielectric nanofluids based on transformer oil and magnetic nanoparticles are attractive due to the controllability of their physical properties by magnetic fields. Fullerene-based nanofluids often exhibit superior dielectric performance. In this study, we combine both iron oxide and fullerene nanoparticles into a transformer oil-based hybrid nanofluid. Using the method of dielectric relaxation spectroscopy, we examine the dielectric response of six samples with different fullerene-magnetic nanoparticle concentrations in the frequency range 0.1 mHz – 10 kHz. The study reveals that the dielectric response of magnetic nanoparticles dominates the dielectric spectrum of the hybrid nanofluids. The spectrum is characterized by a low-frequency Debye-like relaxation process associated with the interfacial polarization mechanism. The process is analyzed in the complex permittivity, electric modulus, and impedance plane. A logarithmic increase in relaxation times is observed with a linearly increasing concentration of fullerenes. The hybrid nanofluid with the highest fullerene concentration of 0.03 %w/V shows the lowest dielectric losses at the mains frequencies. When magnetic nanoparticles are absent, the dielectric spectrum of the fullerene nanofluid resembles that of the pure transformer oil. Around the mains frequencies, the dielectric losses of nanofluid containing only 0.01 %w/V of fullerene have been found lower than those of pure transformer oil. The complex impedance analysis revealed that the electrical conductivity of the hybrid nanofluids has a purely unidirectional character.

Effects of partial Li-substitution on structural, electrical and dielectric properties in La1-xLixSrMn2O5+δ(x = 0.05, 0.10 and 0.15) brownmillerite oxides

In this work we have studied the effects of substitution of lanthanum by Li at the A site on the structural, electrical and dielectric properties of the brownmillerite compounds La1-xLixSrMn2O5+δ(x = 0.05, 0.10 and 0.15). The samples prepared by the sol-gel reaction method. Structural investigation by RX diffraction shows that all compounds crystallize in the cubic structure with space group Pm-3 m at room temperature. The morphology and grain size of the compounds were observed using a scanning electron microscope (SEM). Impedance spectroscopy is used to study the AC electrical properties of these materials in the temperature range 100–200 K and in the frequency range 100 Hz to 1 MHz. To study the dielectric behavior of materials and various physical phenomena. Complex impedance plane plots show the grain contribution for the samples. The Nyquist plot Z' as a function of Z" at different temperatures shows semicircular arcs describing an equivalent circuit.Variation of the modulus and electrical conductivity of the compound shows conduction phenomena and a no-debye type relaxation process. The electrical conductivity was determined using Jonscher's law and the activation energies were determined from the conductivity and the imaginary part of the impedance.

Electrical characterization of CaBi4Ti3ZrO15 ceramic

Layered structured ceramic compounds have significant characteristics in the field of materials research. A new Aurivillius structured compound, CaBi4Ti3ZrO15, is processed by using solid-state reaction technique process. It is calcined at 830 °C followed by a sintering process at 880 °C. Orthorhombic structure of the material is confirmed from X-ray diffraction analysis. Grain size analysis is done through the scanning electron microscopy. Relative permittivity of the sample rises with rise in frequency and temperature and no phase transition is noticed in the experimental temperature regime. The complex impedance spectroscopy method is employed to study the immittance properties of the material within the range of frequency from 100 Hz to 10 MHz and temperature range from 30 to 500 °C. The complex impedance plot confirms the electrical behaviour of the compound which is because of the bulk and bulk interface effect. Absence of third semicircle in the complex impedance plane indicates the complete absence of electrode–materials effect on overall electrical response for this compound. The presence of non-Debye-like relaxation formalism is seen in the Nyquist plots. The temperature-dependent conductivity shows negative temperature coefficient of resistance character obeying Arrhenius equation. The temperature-dependent conductivity shows semiconducting properties of the sample. The response of hysteresis plot for the sample (P-E loop) confirms the ferroelectric property within the material.

Functional Properties of Donor (Al) and Acceptor (Cu) Codoped High Dielectric Constant ZnO Nanoparticles

In this work, we have synthesized donor‐acceptor (Al‐Cu) codoped ZnO nanoparticles with a doping concentration of 0%, 0.25%, 0.5%, and 0.75% by coprecipitation method. The synthesized samples were then annealed at 350°C and 600°C. All the samples showed wurtzite structure of ZnO with no secondary phase. The increase in doping concentration led to deterioration of crystalline quality, while improved crystallinity was observed at higher annealing temperature. The morphological study of these samples showed good grain‐to‐grain contact with less isolated pores. These samples were further characterized by impedance spectroscopy for analyzing dielectric properties. The values of the real part of dielectric constant and tangent loss showed decreasing trend with frequency. The appearance of semicircular arcs in the impedance complex plane plots indicates contribution of grains and grain boundaries and presence of different relaxation processes. 0.5% Al and Cu codoped ZnO showed the best dielectric response with a high value of dielectric constant and low tangent loss.

Effect of sintering temperature and Sm3+ doping on the dielectric properties and non-Ohmic behavior of Ca1-1.5xSmxCu3Ti4.2O12 (x = 0.05 and 0.10) ceramics

The dielectric constant (ε’), dielectric loss tangent (tan δ), and non-Ohmic properties of Sm3+-doped CaCu3Ti4.2O12, i.e., Ca1-1.5xSmxCu3Ti4.2O12 (x = 0.05 and 0.10) ceramics sintered at 1080 °C and 1100 °C were studied. Interestingly, a giant- ε’ (∼9602–16169) with very low tan δ values (∼0.021–0.039) was attained in ceramics sintered at 1100 °C. Moreover, compared to undoped CaCu3Ti4.2O12 ceramics sintered at 1100 °C in our previous work, the tan δ values of Sm3+–doped CaCu3Ti4.2O12 ceramics (x = 0.05 and 0.10) sintered at 1100 °C were found to significantly decrease by 3.06% and 5.68%, respectively. Additionally, these ceramics exhibited non-Ohmic behavior with higher nonlinear coefficient (α)values of ∼ 8.7–22.1. It can be suggested that these very low tan δ values are associated with high grain boundary resistances (Rgb), as is confirmed by the impedance complex plane plot (Z* plot) for this material. Effects of Sm3+ doping and sintering temperature on CaCu3Ti4.2O12 ceramics played a significant role in increasing Rgb values as well as enhancing the nonlinear J-E relationship and dielectric properties of this material. FESEM and elemental mapping with EDXS spectra, as well as XRD techniques, were employed to elucidate the microstructural and structural nature of all ceramics. Moreover, XPS was performed to reveal the Cu+:Cu2+:Cu3+ ratios of these ceramics. The results indicated a semiconducting behavior of the grains. Additionally, it was found that the decreased ε’ values were correlated with lower Cu+:Cu2+ ratios and concurrently increasing levels of Sm3+ dopant.

A new method for determining the d.c. conductivity of powdered materials

The measurement of d.c. ionic conductivity in samples that are not liquids or monolithic solids generally presents a problem. Here we show how the d.c. ionic conductivity determined for a powdered glass can reproduce the conductivity of the monolithic material using a.c. measurements on a sample contained in a sealed NMR tube, in which the structural characteristics can be sequentially determined. While the technique we have developed here has been proof tested and verified against d.c. ionic conductivity measurements made on bulk pieces of Li + ion conducting glasses, the methodology we have developed should be valid for both crystalline and amorphous samples. The tremendous advantage that this technique presents is that it obviates the need to produce pressed pellets of powders under study and in doing so completely avoids the often very difficult and time consuming process of curve fitting the, typically, complicated and convoluted complex impedance plane arcs to separately determine the bulk and intergranular grain boundary impedances.

Rectifying characteristics of semiconductor minerals: A model on seismo-electromagnetic radiation mechanism from ore bodies

Radiations of low to medium frequency (LF-MF) waves from ore deposits with semiconductor properties by rock burst have been reported. However, the radiation mechanism has not been fully understood yet due to the lack of knowledge of the semiconductor properties of ore minerals. So, we clarified the semiconductor properties of natural pyrite (FeS2) by electroetching and indentation-type probe method. Due to the presence of impurities (particularly Pb), the pyrite possesses the quasi-diode junctions with rectifying properties. The current-applied voltage characteristic of the junctions can be represented by an equivalent circuit of the sample, and its forward breakdown voltage is estimated to be 0.3 V. Calculating the surface charge density and separation distance based on the contact electrification, the electric discharge could occur under Paschen's law during the process of contact or separating between ore deposits. Then, the electromagnetic radiation from ore deposits depends on dielectric characteristics, and the skin depth of pyrite for LF-MF waves is estimated to be in the range of 0.1–1 m, indicating the radiation only from the surface deposit excited by seismic wave. Furthermore, the current-voltage characteristics of semiconductor minerals can be changed by the variation of the capacitance and the parallel resistance of the equivalent circuit of semiconductor minerals associated with contact pressure changes. With respect to the dielectric characteristics of ore deposits, the resistivity presents the diameter of circular arc on the complex-plane impedance diagram. Therefore, the continuous monitoring of complex resistivity, such as induced-polarization (IP) method, would detect electromagnetic phenomena associated with earthquakes in dry ore deposits.

AC conductivity and dielectric studies in polypyrrole wrapped tungsten disulphide composites

Using in situ chemical polymerization method, polypyrrole/tungsten disulphide (PPy/WS2) composites were synthesized in various compositions viz. 10, 20, 30, and 40 wt% of WS2 in polypyrrole. Composites were structurally and morphologically characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectra, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy techniques. AC response studies of the composites at room temperature were carried out in the frequency range 50 Hz–1 MHz. When compared with pristine PPy, the composites have exhibited enhanced conductivity and the same has been reflected in the complex plane impedance plots. This indicates that the conduction mechanism is due to the hopping of charge carriers. The loss tangent curves of the composites have been explained using Rezlescu model.

Giant dielectric constant, dielectric relaxations, and tunable properties of Sm2/3Cu3Ti4O12 ceramics

AbstractThe polycrystalline Sm2/3Cu3Ti4O12 (SCTO) ceramics have been prepared by solid‐state reaction. The crystallinity of the compound has been investigated by Rietveld refinement which has revealed a cubic structure with space group Im3. It is observed that at low frequencies, SCTO ceramic exhibits tremendously high values of dielectric permittivity ε′, larger than 32,000, at room temperature. Two distinct, thermally triggered, dielectric relaxations have been noted. This mechanism has been confirmed through impedance analysis of the ceramics. The complex impedance plane shows three semicircles, which confirm the existence of two dielectric relaxations in SCTO ceramics. In general, the electrical as well as dielectric behavior of SCTO ceramics are seen to be reasonably analogous to those of CaCu3Ti4O12 (CCTO) ceramics. The emergence of the enormous dielectric constant in SCTO ceramic is accredited to the combined effect of polarization both at the sample‐electrode interface as well as at the insulating grain boundary interface. The SCTO ceramics are identical to the CCTO ceramics in their structure and composition and hence, as the above results indicate, the IBLC effect mechanism, originally put forward for CCTO ceramics, is furthermore plausible to account for the mammoth values of dielectric constant in SCTO ceramics.

Enhancing the electrical properties of Bi4Ti3O12 (BiT) matrix by special alloying and sintering

In this work, the electrical properties of Bi4Ti3O12 (BiT) were investigated; those presenting interesting electrical and dielectric properties in the radiofrequency (RF) and microwave (MW) range were analysed. BiT has many applications in telecommunication systems and MW circuits. It was synthesized by the solid-state reaction method, and X-ray diffraction was used for structural characterization of this phase. The properties in the RF range were measured by impedance spectroscopy. An imaginary impedance relaxation peak and high values for real impedance were found. The complex impedance plane plots show the presence of a semicircle that was adjusted by an R-CPE circuit, presenting a thermoactive process for the load carriers. The dielectric properties in the MW range were measured using the Hakki–Coleman method, and the thermal stability was measured using the Silva–Fernandes–Sombra (SFS) technique. BiT was tested as an antenna and distant field parameters were measured and simulated.

Dielectric properties of soil mixed with urea fertilizer over 20 Hz to 2 MHz frequency range

The dielectric properties of sandy soil for various moisture contents of distilled water and Urea-fluid solutions in soil are estimated in the lower frequency range from 20 Hz to 2 MHz using precision LCR meter. The spectra of complex permittivity e*(ω), loss tangent tan δ(ω), electrical conductivity σ*(ω), and complex impedance Z*(ω) plane plots of these soil-fluid system have been investigated for various moisture contents of different concentrations of Urea solution in the soil samples. The dielectric constant and dielectric loss of the soil increase with increase in moisture content of different concentrations of Urea solution in the soil. The dielectric constant and dielectric loss of the soil increases significantly with the decrease in frequency over the given frequency range. The complex impedance plane (Zʹ versus Zʺ) plot separates electrode polarization and bulk material phenomena, which can also be observed in the dielectric loss tangent peaks.