Dielectric Loss Values Research Articles

Structural and Dielectric Studies of Ni1−xAlxFe2O4

The nanoparticles of Ni1−xAlxFe2O4(x = 0,0.5) were synthesized via using sol-gel route and studied the structural and dielectric effect of aluminium content on Nickel site. The X-ray diffraction (XRD) revealed the single-phase cubic spinel structure of the parent compound. The lattice constant, volume, density, bond lengths, specific surface area and crystallite size were determined from the Rietveld refinement. In the Raman analysis, there are five active modes present in the synthesized samples. FTIR spectroscopy confirmed the formation of spinel ferrite and showed the characteristics absorption bands of metal oxygen (Fe-O) observed around 424-450 and 601-620 cm−1 corresponding to the stretching vibration frequency of the metal-oxygen at the octahedral site and tetrahedral site respectively. Dielectric behaviour showed that the value of dielectric constant (ε') and tangent loss (tanδ) decreases with frequency and confirmed the general behaviour of ferrites. The AC Conductivity (σac) was found lower in Ni0.5Al0.5Fe2O4 compared to NiFe2O4.

Syntheses, spectroscopic characterization, and electrical properties of important semiconducting organic compound

This work proposes the synthesis of new azomethine by the reaction of enaminone with an appropriate aldehyde. The new compound was identified by NMR (1H and 13C), and others techniques such as: UV–Vis spectroscopy, Fourier Transform Infra-red spectroscopy (FT-IR) and X-ray diffraction (XRD).The optical data shows the synthesized azomethine exhibit low band gaps. (Eg =2.87 eV). Electrical conductivity study indicates that conductivity of product is in the range of ∼ 10−6 S/cm. . So, it is evaluated that the sample is a typical organic semiconductor as its conductivity increases with increasing temperature and the electronic parameters such as activation energy and room-temperature conductivity are in the regime of semiconductors. It is also found that the dielectric constant and the dielectric loss values increase with temperature and decrease with frequencies.Furthermore, the results obtained in this pioneering study are thoughtfully discussed in the context of existing literature. This study is opening doors to potential applications in chemistry.

Construction of sandwich‐layered polyimide hybrid films containing double core–shell structured fillers for high energy storage density

AbstractThe inherent low dielectric constant of polyimide (PI) dielectrics restricts their applications to become a component of high energy density film capacitors. In this work, double core–shell structured barium titanate@magnesium oxide@polydopamine (BaTiO3@MgO@PDA) nanoparticles were synthesized successfully and utilized as high dielectric constant functional fillers for PIs, in which the insulating MgO layer meliorated dielectric constant difference between BaTiO3 and PI matrix, and the organic PDA layer improved the compatibility between the inorganic fillers and PI matrices. Then, a series of sandwich‐structured PI‐based hybrid films was prepared through a layer‐by‐layer solution casting method. The middle layer of pure PI with excellent insulating properties effectively suppressed charge injection. With the combination of sandwich structure and the BaTiO3@MgO@PDA nanoparticles, the PI hybrid film containing 15 wt% fillers in the outer layers achieved the maximum breakdown strength of 425.68 kV/mm and the maximum energy density of 5.132 J/cm3, which was 68.3% and 413% higher than those of pure PI film, respectively, meanwhile maintained a low dielectric loss value of 0.0083 at 1 kHz. The introduction of BaTiO3@MgO@PDA enhanced the interfacial polarization due to the high barrier energy between adjacent layers preventing the transfer of electrons and weakening the leakage current in the sandwich‐structured composite film. This work demonstrates that an appropriate combination of high dielectric hybrid fillers and multilayer structure can effectively increase the energy storage density of PI substrate for high‐temperature energy storage applications.Highlights The double core–shell structured BaTiO3@MgO@PDA was synthesized successfully. The sandwich‐structured hybrid films were prepared by layer‐by‐layer method. The energy density of hybrid films reached a high value of 5.132 J/cm3.

Effect of CeO2 doping on structural, electrical and mechanical properties of basalt fibers

Developing basalt fibers with low dielectric properties and excellent water resistance is still very challenging. To overcome this problem, basalt glass and basalt fibers with different CeO2 content were prepared in this paper by using the conventional melt cooling method and single hole drawing process. The relationship between CeO2 content (0 wt%-4 wt%), the structural, electrical and mechanical properties of basalt fibers was investigated by using XRD, Raman, dielectric properties tester and fiber strength and elongation meter. The results showed that when the weight content of CeO2 was 2 wt%, the glass had the most stable network structure with the largest degree of linkage, resulting in a 75 % increase in water resistance, the lowest values of dielectric constant (6.25) and dielectric loss (4.38 × 10−3), and a 33 % increase in tensile strength.

Modulation effect of Zr-Sm co-doped on microwave absorption performance of barium ferrite

Zr-Sm co-doped barium ferrites BaFe12–2x(ZrSm)xO19(x = 0, 0.2, 0.4, 0.6) were successfully prepared by sol-gel method. The effects of Zr-Sm co-doped on phase formation, microscopic morphology, magnetic parameters, electromagnetic and microwave absorption properties of barium ferrite were studied. The results show that the saturation magnetization(Ms) of BaFe12–2x(ZrSm)xO19 first increases and then decreases, the coercivity(Hc) first decreases and then increases with the increase of doping amount(x) of Zr-Sm. Large grain size and sheet morphology lead to the transition of BaFe11.6(ZrSm)0.2O19 towards soft magnetic properties. The introduction of Zr-Sm increases the amount of oxygen vacancies, and dielectric loss value of material is obviously enhanced, this improves the polarization relaxation of materials. At the same time, multiple natural resonance peaks appeared in the virtual part of the permeability (μ"), which regulated the absorbing properties of samples. The best microwave absorption properties of sample is obtained when doping x = 0.2, at the thickness of 2.8 mm, the maximum reflection loss(RL) is − 51.75 dB. The effective absorption bandwidth (RL ≤ −10 dB) is 4.4 GHz, it covers almost all the X-band(8–12 GHz). Compared with existing doped barium ferrite, the material possesses a greater reflection loss and excellent prospects in the field of microwave absorption.

Effects of Ce3+ doping on magnetic and dielectric properties of cobalt zinc manganese ferrites for high frequency applications

In this paper, a constant quantity of Co2+ ions and a series of Ce3+ ions were used to substitute Fe3+ ions to control the magnetic and electrical properties of the pristine Zn–Mn nanoferrites with the formula Co0.5Zn0.25Mn0.25CexFe2-xO4 (CZMC). The addition of a suitable content of Ce3+ ions (x = 0.1) enhanced the magnetization (with an enhancing ratio of 9.43 %), initial permeability (with an enhancing ratio of 31.06 %), and coercivity (with a decreasing ratio of 12.86 %). The CZMC nanoferrites can operate from 13.5 GHz to 16.5 GHz, which can be utilized in high frequency-based technical purposes such as magnetic memories, filters, and transformer cores. The AC conductivity results of the CZMC nanoferrites are in correspondence with Jonscher's single-power law, and the conduction mechanism is established to be attributed to the overlapping large-polaron tunneling model. Nyquist plots of the samples revealed that the diameters of the semicircles decrease as the temperature increases, confirming the semiconducting behavior with one semicircle due to the electrode and grain boundary contributions to the conduction process. The high-frequency response of the CZMC nanoferrites revealed that they could operate in the frequency range of 13.5 GHz–16.5 GHz, which is suitable for electronic and microwave devices. The dielectric loss value reduces with Ce replacement (with a decreasing ratio of 66 %), suggesting it might be a candidate for planar inductor and transformer cores at high-frequency applications.

Low dielectric constant and highly intrinsic thermal conductivity fluorine‐containing epoxy resins with ordered liquid crystal structures

AbstractEpoxy resins with a high dielectric constant and low intrinsic thermal conductivity coefficient cannot meet the current application requirements of advanced electronic and electrical equipment. Therefore, novel fluorine‐containing liquid crystal epoxy compounds (TFSAEy) with fluorinated groups, biphenyl units, and flexible alkyl chains are first synthesized via amidation and esterification reactions. Then, 4,4′‐diaminodiphenylmethane (DDM) is used as a curing agent to prepare the corresponding fluorine‐containing liquid crystal epoxy resins. The obtained dielectric constant (ε) and dielectric loss (tan δ) values of TFSAEy/DDM at 1 MHz are 2.54 and 0.025, respectively, which are significantly lower than those of conventional epoxy resins (E‐51/DDM, 3.52 and 0.038). Additionally, the intrinsic thermal conductivity coefficient (λ) of TFSAEy/DDM is 0.36 W/(m·K), 71.4% higher than that of E‐51/DDM (0.21 W/(m·K)). Meanwhile, the corresponding elastic modulus, hardness, glass transition temperature, and heat resistance index of TFSAEy/DDM are 5.73 GPa, 0.35 GPa, 213.5°C, and 188.7°C, respectively, all superior to those of E‐51/DDM (3.68 GPa, 0.27 GPa, 107.2°C, and 174.8°C), presenting potential application in high‐heating electronic component packaging and printed circuit boards.

Insights into structural, electronic, optical properties, and impedance spectroscopy of semi-doped perovskite Nd0.5Ba0.5CoO3: A theoretical and experimental study

In this study, the electronic, structural, and optical properties of semi-doped perovskite Nd0.5Ba0.5CoO3 (NBCO) were investigate using the CASTEP software, which relies on density functional theory (DFT) along with the correlation function of generalized gradient approximation (GGA) and Perdew-Burke-Ernzerhof (PBE). The mesh parameters of the (super) cell indicate that NBCO adopts an orthorhombic structure in the Pmmm space group, featuring a Coulomb Energy (EC) of approximately −244 eV. DFT and total density of states (DOS) analyses reveal that the as-prepared perovskite manifests metallic characteristics, and a notable covalent interaction is observed between the O-p and Co-d spin states, indicating strong hybridization between these orbitals. Remarkably, NBCO demonstrates 100 % spin polarization (P) at the Fermi level, with a calculated total magnetic moment of approximately 3.44 μB. Moreover, low dielectric loss (tgδ) values suggest facile electron movement, and impedance spectroscopy illustrates a dielectric relaxation phenomenon. DFT calculations predict an orthorhombic crystal structure with higher electron density at cobalt atom positions. Band structure and DOS analyses affirm metallic behavior owing to the robust hybridization between oxygen-p and cobalt-d orbitals. Optical property assessments reveal potential applications in spintronics and optoelectronics, with notable absorption in the ultraviolet–visible range. The conductivity spectra from impedance spectroscopy contribute to understanding temperature-dependent charge transport mechanisms. Dielectric constants decrease with increasing frequency and temperature, while dielectric losses remain low, indicating efficient electron movement. The material adheres to a metallic conduction mechanism as described by Drude's law, and the material's 100 % spin polarization at the Fermi level and a total magnetic moment of 3.44 μB are significant findings. Negative dielectric constants observed at specific frequencies suggest potential applications in metamaterials. Overall, the determined properties position NBCO cobaltite as a promising candidate for high-frequency devices, spintronic components, and sensors.

Microstructure, Dielectric Properties and Bond Characteristics of Lithium Aluminosilicate Glass-Ceramics with Various Li/Na Molar Ratio

The advent of 5G technology presented new challenges regarding the high-frequency characteristics of electrical signals and their impact on the cover glass properties of electronic devices. This study aimed to analyze the effect of the Li/Na molar ratio on the dielectric and mechanical properties, as well as the structural characteristics, of lithium aluminosilicate glass-ceramics. Using the melting method, we prepared lithium aluminosilicate base glasses and subsequently crystallized them by adjusting the molar ratio. XRD and TEM analyses were employed to investigate the resultant structures and crystal formation in the five base glasses. It was observed that Li2Si2O5 and LiAlSi4O10 crystals precipitated, exhibiting varying degrees of crystallinity and crystal ratios. Through a comparison of dielectric properties before and after crystallization, it was found that the dielectric constants of the glass-ceramics were consistently reduced. This decrease can be attributed to the lower dielectric constants exhibited by both crystalline phases compared to the parent lithium aluminosilicate glasses. Furthermore, the presence of glass crystals effectively immobilized the alkali metal ions within the glass phase, impeding their movement under an electric field. Consequently, the dielectric loss value of the glass-ceramics decreased with the increasing amount of precipitated crystals. By carefully adjusting the composition and optimizing the crystallization process, we successfully produced lithium aluminosilicate glass-ceramics, demonstrating excellent mechanical and optical properties, coupled with low dielectric properties.

Electrical and magnetic properties of MF/CuAl nanocomposites

Abstract This study investigated the effects of CuAl2O4 (CuAl) on four types of spinel ferrites: CoFe2O4 (CoF), NiFe2O4 (NiF), MgFe2O4 (MgF), and ZnFe2O4 (ZnF) with regards to their electrical characteristics and microscopic magnetic behavior. According to the Seebeck coefficient (φ), the nanocomposites have a mixture of positive and negative charge carriers, except for CoF/CuAl, which has a positive charge carrier only. Depending on the temperature, the DC conductivity of all MF/CuAl nanocomposites has a conductor and semiconductor behavior. The dielectric properties were studied at different frequencies (100–10^8 Hz) and temperatures (300–673 K). The results demonstrated how temperature and frequency affect AC operating mechanisms. The high values of dielectric loss for all nanocomposites confirm their applicability in high-frequency microwave devices. The impedance study revealed that the equivalent circuit for all MF/CuAl nanocomposites is a mixture of R, L, and C. Temperature-magnetization graphs were obtained for all nanocomposites, indicating ferrimagnetic behavior except ZnF/CuAl. The magnetic transition temperature (T Cm), the Curie–Weiss constant (θ CW), and the effective magnetic moments (μ eff) for all nanocomposites were determined. The MF/CuAl samples were analyzed using ESR spectroscopy at room temperature. The spectra were distorted but remained distinct, potent, and sweeping. The g-factor values deviate from the free electron, which suggests that the Fe3+–O–Fe3+ superexchange interaction has changed. In addition, the interaction effect between MF and CuAl is discussed.

Low‐k dielectric materials derived from ZSM‐5 zeolite

AbstractLow‐k dielectric materials were prepared by sintering ZSM‐5 zeolite powder compacts at temperatures ranged 1200–1300°C, and the microwave dielectric characteristics were investigated together with the structure evolution during sintering. It was failed to obtain ZSM‐5 ceramics by high temperature sintering because the densification could never occur below the tolerable temperature and the ordered porous structure completely collapsed above the tolerable temperature. The structure changed from ZSM‐5 zeolite to SiO2‐Al2O3 glass at 1240°C, and finally to SiO2‐based cristobalite ceramics above 1275°C. A low dielectric constant (2.63‐2.78) combined with low dielectric loss (< 0.0005 at 18 GHz) and small temperature coefficient of resonant frequency (varied from ‐18.6 to ‐8.1 ppm/°C) was achieved in the present materials, and the value of dielectric loss was the lowest one achieved so far in the dielectric materials with a dielectric constant lower than 3. With the structure evolution from ZSM‐5 zeolite to SiO2‐Al2O3 glass and finally to SiO2‐based cristobalite ceramics, the dielectric constant increased from 2.27 to 2.78, while the Qf value indicated a complicated variation tendency, and the higher Qf values were achieved in the amorphous and crystalline states, while significant drop was determined in the partial amorphous state. It should be a great challenge to prepare dense zeolite ceramics without collapse of ordered porous structure, and then the ultra‐low dielectric constant materials with high Q could be expected.

Impact of pH levels on the morphological, dielectric and impedance spectral behaviour of cobalt oxide nanomaterials

Pure Co3O4 nanomaterials were synthesized by using Sol-Gel technique at various pH levels (7, 8 and 9). Morphological and structural analysis was done by X-ray diffraction method (XRD), scanning electron microscope (SEM) and energy-dispersive spectroscopy EDX. The X-ray diffraction patterns revealed that the prepared samples crystallized in a cubic structure without any impurities. SEM micrographs validated the influence of pH in altering the morphology of the synthesized compound. The elemental spectrum analysis EDX confirms the presence of cobalt and oxygen without any impurities. Variation of dielectric constant, dielectric loss and impedance were analyzed for various temperatures and different pH values. Dielectric loss value increases at high temperature due to the thermal disturbance of the atoms. Cole-Cole impedance plot gives the information about grain and grain boundaries. DC electrical conductivity values of Co3O4 nanomaterials in the temperature range 40ºC to 250ºC increases with increase in pH level from 7 to 9. Arrhenius plot of Co3O4 nanoparticles confirmed that the activation energy at various temperature increases with increase in pH levels upto 8, then decreases for pH level 9.

Structural, dielectric, and optical properties based on spinel ferrite (Mn0.5Fe1.5Mg0.5Ni0.5O4) nanoparticles filler reinforced PVA for optoelectronic, laser CUT-OFF filters and energy storage devices

The fabrication of polymer nanocomposites with specialized traits is gaining popularity across the world due to novel added qualities. In this work we used a flash auto-combustion method to prepare Mn0.5Fe1.5Mg0.5Ni0.5O4 nanoparticles and the casting method to prepare Mn0.5Fe1.5Mg0.5Ni0.5O4/PVA nanocomposite polymer films with doping of nanoparticles various from 1–5 wt.%. The effect of Mn0.5Fe1.5Mg0.5Ni0.5O4 nanoparticles addition on the structural, optical, and dielectric characteristics of nanocomposite polymer films was analyzed. The structural properties were studied using x-ray diffraction pattern, high resolution transmission electron microscope, Fourier transform infrared, and field emission scanning electron microscope. The effects of nanoparticles doping on ac conductivity, electric modulus, impedance, and dielectric constant were investigated. It shows that Mn0.5Fe1.5Mg0.5Ni0.5O4/PVA nanocomposite films have higher values of permittivity and ac conductivity than PVA and exhibit lower values of dielectric loss, electric modulus, and impedance. The optical properties showed the indirect optical decreased from 4.8 to 4.4 eV. According to the experimental results, these nanocomposite polymer films show promise for laser CUT-OFF filters and energy storage devices.

Enhanced dielectric and hydrophobic behaviour of aurin based polybenzoxazine dye composites

Herein, three novel bi-functional benzoxazines were synthesized using aurin as the precursor phenol with three different aromatic amines (i.e.) aniline, fluoroaniline, and trifluoromethylaniline with paraformaldehyde through Mannich condensation. The structural confirmation was done using FTIR and proton NMR. The effects of substituents present in the amines on the curing behaviour and thermal stability were studied using DSC and TGA. The aurin based trifluoromethyl substituted benzoxazine shows better thermal stability than that of the other two benzoxazines and it was selected for the preparation of composites with varying weight percentages of graphitic carbon nitride derived from dicyandiamide (Dicy-GCN) to utilize them for high k applications. The dielectric behaviour and thermal properties of both neat polymer matrix and composites were studied and compared. The 15 wt% Dicy-GCN reinforced composite shows the highest dielectric constant value of 10.25, with a low dielectric loss value of 0.046 at 1 MHz frequency. The polybenzoxazine composites developed show better thermal stability and superhydrophobic behaviour than those of neat polybenzoxazine matrix. These properties ascertain that the aurin based bifunctional polybenzoxazines and its composites can be considered for high-performance high k applications.

Structural, Physical, Magnetic, and Dielectric Study of Glassy and Crystalline Bismuth Zinc Silicates

AbstractThe current study aims to thoroughly analyze the optical, magnetic, and dielectric properties of the glass and glass-ceramics in the system Bi2O3.ZnO.SiO2 with stoichiometric composition xBi12SiO20.(100-x)Zn2SiO4(x = 0, 10, 30, 50, 70, 90, and 100). The systematic dependence on density, Bi2O3, and the presence of interphases was studied. Fourier transform infrared (FTIR) spectra of the glass-ceramic samples certify the changes occurring in structure from amorphous to crystalline form where more intense, sharp, narrow bands were observed. Both 10B and 30B samples display more ultraviolet (UV) absorbance than the remaining samples. Upon introducing Bi2O3, the glass sample's color gradually changed from brown to pale yellow. In the vibrating sample magnetometer (VSM) study, the highest (9.22 × 10-7 emu/g) and lowest (4.53 × 10-7 emu/g) magnetic susceptibility were noticed for 30B and 70B samples, respectively. Further, all glass ceramics display diamagnetic properties due to the existence of Bi ions. The glass-ceramic samples showed better dielectric properties than glass samples due to changes from the amorphous nature of the glassy phase (high dielectric loss) to the well-ordered structure of the corresponding glass-ceramic (low dielectric loss). The glass ceramic sample of 100B attained much lower dielectric loss values (0.002, f = 106 Hz) than the corresponding glass sample (0.01, f = 106Hz) which could be helpful for electric storage devices, i.e. capacitors, supercapacitors, batteries, etc. Besides, the high-quality factor (Q = 2758) of the same glass-ceramic sample makes it promising in Radio Frequency (RF) circuits or other high- frequency applications.

An elucidation of symmetric supercapacitor with crustacean‐based polymer blend electrolyte

AbstractSearching for alternative materials that have biodegradable properties is one of the efforts to increase knowledge and green technology that contributes to the reduction of waste produced from electronics. A biodegradable biopolymer electrolyte system based on polyvinyl alcohol‐chitosan blend is prepared using an easy and affordable method called solution cast technique. Lithium acetate (LiOAc) and ethylene carbonate (EC) are incorporated as charge carrier and plasticizing agent. The plasticization effect of EC concentrations on physical structure has been investigated and reported. The real and imaginary parts of dielectric permittivity confirmed that the highest dielectric constant and loss values are recorded at low‐frequencies regions. A disruption in the crystalline region of the film can be observed with the existence of LiOAc and EC. The inclusion of EC promotes the ions dissociation thus enhanced the amorphous region of the electrolytes which is beneficial for ionic conduction. Linear sweep voltammetry analysis revealed that the highest conducting electrolyte is electrochemically stable up to 1.82 V. No redox peaks are shown in the cyclic voltammetry of the fabricated supercapacitor. The supercapacitor showed a great performance with average specific capacitance of 130 F g−1.

Engineering DyCrO3 ceramics toward room-temperature high-κ dielectric applications

The search for a high-κ dielectric material that combines a high dielectric constant (ϵ′) and low dielectric loss is very crucial because of its widespread use in gate dielectrics to avoid the leakage current that arises due to continued miniaturization of present SiO2-based metal-oxide semiconductor field-effect transistor devices. RCrO3 (R is a rare-earth ion) materials have been at the center of interest because of their intriguing ferroelectric and magnetic properties, as well as their room-temperature colossal dielectric constant (CDC) values. Although CDC (ϵ′∼104) in RCrO3 materials is quite common, it is unsuitable for device applications since it is associated with a larger dielectric loss value (tan δ∼7 at 11 kHz). Here we have focused on polycrystalline DyCrO3, prepared using multiple synthesis techniques, and thoroughly investigated the origin and tuning of the various dielectric relaxations that give rise to CDC and large dielectric loss values. A clear understanding of the origin of dielectric relaxations enables us to design a specially synthesized DyCrO3 (SPS-DCO) in which the extrinsic dielectric relaxations driven large dielectric loss values can be completely suppressed and which is found to be associated with optimized high-κ dielectric properties [ϵ′∼130, tan δ∼0.06, and temperature coefficient of dielectric constant (TCϵ) ∼ 2280 ppm/K at 11 kHz, 300 K]. The only remaining intrinsic Debye-type dielectric relaxation in SPS-DCO arises due to electric-field-assisted charge hopping among various valences of Cr (investigated using x-ray photoelectron spectroscopy) that presently limits the lowest attainable loss value.

High-Performance Polyimide Films Derived from Biomass-Based Furfural: Fabrication and Properties

The development of renewable polymers as alternatives to the petroleum-based ones has received significant attention due to the increasing depletion of fossil oil and the associated environmental concerns. In this study, a semi-biomass-based polyimide (PI) film was successfully synthesized, using biomass-derived furfural (HMFA) as one of the raw materials. A two-step approach was first developed for this process: (1) conversion of HMFA to 3,3,4,4-biphenyltetracarboxylic acid dianhydride (BPDA) and (2) polymerization of BPDA with p-phenylenediamine (PPD) to form a PI film. The fabricated PI film demonstrated excellent properties, such as a high thermal decomposition temperature up to 600 °C, a satisfactory glass transition temperature (Tg) exceeding 365 °C, a coefficient of thermal expansion (CTE) of ≈30 ppm/K, a tensile strength greater than 120 MPa, a dielectric constant value below 3.4, a dielectric loss value of less than 0.02, and a 24 h water absorption rate below 0.8%. These performances are comparable to the petrochemical-based PI. This work offers a promising strategy for utilizing biomass-derived materials in polyimide synthesis and would drive a new wave of advancements in polymer science.

Impact of Process Parameters and Dopant Concentration on Structural, Magnetic, and Dielectric Properties of Dysprosium-doped Nickel-Zinc Ferrites Synthesized by Microwave Hydrothermal Method

This study aims to investigate the impact of substituting Dy3+ ions on the structural, magnetic and dielectric properties of Nickel Zinc (Ni-Zn) ferrites, which have the chemical formula Ni0.5Zn0.5DyxFe2-xO4 (where x = 0, 0.01, 0.03, 0.05, 0.07, and 0.09). These ferrites were synthesized using a microwave hydrothermal technique with different process parameters. Structural characterization of the synthesized powders was carried out using X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR). The XRD analysis confirmed the presence of a pure spinel phase for Dy concentrations (x) up to 0.05. However, when x ≥ 0.07, an additional orthoferrite phase (DyFeO3) was observed along with the spinel phase. FTIR spectra revealed a shift in low-frequency wave numbers due to Dy3+ ion substitution. The size and morphology of the synthesized powder particles were examined using field emission scanning electron microscopy (FESEM). The powder compacts were sintered using microwave processing at 900 °C for 40 min. The increase in dc. resistivity is observed with an increase in Dy3+ concentration, mainly due to the change in the hopping mechanism with the substitution concentration. Dielectric properties such as dielectric constant and loss are measured in the frequency range of 100 Hz to 1.8 GHz. The high value of dielectric constant and loss observed in the low-frequency region compared to the high-frequency region. Maxwell’s Wagner model and ‘Koop’s theory explains the variation in dielectric properties with the frequency. The magnetic hysteresis loops were measured at different temperatures and observed to enhance the low-temperature magnetic properties compared to room temperature. The results suggest that the magnetic and dielectric properties of the investigated samples can be adjusted by varying the concentration of Dy3+ ions, providing the ability to tailor these properties according to specific application requirements.

Investigation of Structural and Dielectric Properties of Sr doped LaCrO3Synthesized by Auto-Combustion Method

We synthesized the undoped lanthanum chromium oxide, LaCrO3 (LCO), and Strontium (Sr) doped La1-xSrxCrO3 (x=0.1) perovskite compounds using auto-combution method. X-ray Diffraction technique reveals that both the samples possess Cubic crystal structure with Pm-3m space group. Furthermore, room temperature dielectrical properties of both the samples were emphasized. Dielectric constant and loss value of both the samples decreases as frequency increases attributed to Maxwell-Wagner type of relaxation.