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The nanoparticle spinel ferrites Mg0.5Zn0.5CexLaxFe2-2xO4 (x = 0.0, 0.0125, 0.025, 0.0375, 0.05) were synthesized by mean of co-precipitation method. These magnetic nanoparticles were sintered at 750 °C for 8 h. XRD patterns confirmed the formation of the cubic spinel structure of prepared nanoparticles. The lattice constant of nanoparticle ferrites increased, while crystallite size decreased with doping content (x). Pure ferrite sample has an optical bandgap of 2.61 eV, and it increases from 1.73 to 2.17 eV as concentration (x) is changed from 0.0125 to 0.05. The electrical dc resistivity is of the order of 1010 Ω cm for doping content (x) from 0 to 0.0375 and has a maximum value of 5.48617 × 1012 Ω cm for content x = 0.05. The Curie temperature (Tc) decreased 433–373 K as concentration (x) was increased. The dielectric constant, dielectric loss, and impedance are reduced with the increase of frequency. The dielectric constant, as well as the dielectric loss diminished while impedance increased as doping of cerium and lanthanum, was increased. [ABSTRACT FROM AUTHOR]

Cost-effective and controllable synthesis of M0.25Ni0.15Cu0.25Co0.35Fe2O4 (M2+ = Mg2+, Mn2+, and Cd2+) ferrites via the sol–gel auto-combustion technique. The impact of divalent cations on the structural, dielectric, and optoelectrical properties of ferrites was examined by XRD, FTIR, Raman, LCR, UV–Vis, and two probe I-V measurement techniques. The crystallite size was 52.66 nm, and the minimum specific surface area was observed 5.1507 m2/g for Mg2+ doped NCCF ferrite. The FTIR and Raman analysis also confirmed the substitution of divalent cations (M2+ = Mg2+, Mn2+, and Cd2+) at their respective lattice sites. The maximum energy bandgap was 1.67 eV Mg2+-doped NCCF ferrite as compared to other divalent ion-doped ferrites. The dielectric loss decreased while the ac conductivity increased with increasing frequency, and the minimum values were observed for Mg2+-doped NCCF ferrite. The activation energy was observed maximum for Mg2+-doped NCCF ferrite (0.2234 eV). Due to incredible properties including small specific surface area, large energy band gap, high resistivity, and loss dielectric loss of Mg2+-doped NCCF ferrite have potential applications in different fields. [ABSTRACT FROM AUTHOR]

Low temperature and more efficient sol-gel auto combustion process was utilized to synthesize Co 0.3 Li 0.1 Ca 0.5 Fe 2.1- x La x O 4 [ La-CLCF ] spinel ferrites (where x = 0.00, 0.01, 0.02, 0.03, 0.04, and,0.05). The La-CLCF sample's structural, optoelectrical, dielectric, and magnetic properties were examined as a result of La3+ doping. All synthesized La-CLCF samples have single-phased spinel matrix, according to X-ray diffraction (XRD) analysis. It was found that the crystallite size was 11 nm, and the bandgap energy of 3.45 eV for La3+ doping x = 0.03. The resistivity and activation energy both were increased with the substitution of La3+ in the CLCF spinel matrix, while the peak position of temperature coefficient of resistance (TCR) percentage was − 3.92%/K at 372 K for sample x = 0.03. The alternating current conductivity improves with frequency, whereas the dielectric constant and tangent loss decrease as frequency increases. Further, the saturation magnetization and the microwave operating frequency for all the samples were reduced with the doping of La3+. The minimum coercivity was 242 Oe at x = 0.03. Our study suggested that the Co 0.3 Li 0.1 Ca 0.5 Fe 2.07 La 0.03 O 4 sample is tested as an active material for potential use in high-frequency applications, electromagnetic wave absorbing material, and evaluating the sensitivity of infrared (IR) detectors used in night vision bolometers. [Display omitted] • Co 0.3 Li 0.1 Ca 0.5 Fe 2.1- x La x O 4 spinel ferrites preparation via SGAC route. • The peak position of TCR was − 3.92%/K at 372 K for sample x = 0.03. • The minimum coercivity was 242 Oe for La3+ doping x = 0.03 • The sample x = 0.03 is a potential candidate for high-frequency applications, electromagnetic wave absorbing material, and bolometers. [ABSTRACT FROM AUTHOR]

Y-type hexaferrite ceramic materials of nominal composition Ba 2 Co 2 Cr x Y x Fe 12-2x O 22 (x = 0.00, 0.03, 0.06, 0.09, and 0.12) were synthesized by sol-gel auto combustion route. Y-type hexaferrites are technologically important ceramic materials for fabricating modern electronic devices and microwave absorbers due to their unique electrical and dielectric properties and reflection loss behavior. XRD classifies the single-phase formations with space group R 3 ‾ m. The crystallite size of the synthesized samples was calculated in (34–41) nm range. The specific absorption band in FTIR spectra approves the (Fe–O) stretching vibrations at wavenumbers 446 and 478 cm−1. The substitution of iron by Cr3+ and Y3+ increases DC resistivity from 1.03 × 1011 to 1.17 × 1012 Ω cm by limiting the electrons jumping between ferrous and ferric ions. The activation energy and drift mobility were also calculated among the substituting content of Cr3+-Y3+. The dielectric response in 1 MHz–6 GHz frequency was determined and the effect of substitution has been observed. The Maxwell-Wagner (MW) bilayer model is used to study dispersion in dielectric parameters with reference to applied frequency. The maximum values of dielectric losses were obtained at 6 GHz in the range of 0.37–0.60. The coercivity values confirms the soft magnetic nature of synthesized samples. The microwave absorption (MW) properties of synthesized materials were improved upon Cr3+-Y3+ substitution. Minimum reflection loss R Lmin = −66 dB (99.99% absorption of MW) at 1.46 GHz frequency and 1.96 mm thickness was obtained for x = 0.09 composition. All investigated samples are efficient materials for stealth technology, radar cross-reduction, EM interference shielding, and high-frequency applications. [ABSTRACT FROM AUTHOR]

Due to their outstanding properties, low cost, and environmental friendliness, mixed transition metal oxides are frequently used in various applications. In this study, Ce3+ doped CdFe 2 O 4 powder samples were prepared through the co-precipitation process. A peak shift was observed towards a lower 2 θ angle with the substitution of Ce3+ at their lattice site and the lattice constant has a maximum value for the x = 0.06 sample with the crystallite size of 34 nm. Moreover, for x = 0.06 sample, the resistivity was found in the order of 106 Ω cm and the dielectric tangent loss had a smaller value. The electrical and dielectric analysis of the as-prepared x = 0.06 sample indicate that it is the best for high-frequency applications. • The Ce3+ doped CdFe 2 O 4 samples were prepared via the co-precipitation route. • The crystallite size was found 34 nm for a sample having Ce3+ x = 0.06 sample. • The x = 0.06 sample resistivity was observed in the order of 106 Ω cm. • The dielectric tangent loss has a smaller value for the x = 0.06 sample. • The electrical and dielectric properties suggested that x = 0.06 sample is suitable for high-frequency applications. [ABSTRACT FROM AUTHOR]

Z n 0.5 C o 0.25 C u 0.25 F e 2 − x L a x O 4 (x = 0.0, 0.0125, 0.025, 0.0375, 0.05) ferrite powders with uniform distribution of ions and close-packed configuration were prepared via sol-gel auto-combustion route. XRD spectra showed the formation of spinel-phase cubic crystalline structure. SEM results revealed that the irregularity in size and shape of particles increases, and particle distribution uniformity decreases with La3+ concentration. Moreover, each curve of the UV–vis spectra revealed two optical energy band gaps. More importantly, DC resistivity (ρ) and the activation energy (Δ E) have minimum values at x = 0.0375. The dielectric loss was explained according to Maxwell-Wager space charge polarization. The P-E loop showed the ferroelectric nature of the synthesized samples. Moreover, VSM results revealed that the as-prepared samples possessed maximum saturation magnetization (M S = 56.77 ± 0.0283) and 8–12 GHz operating microwave frequency (ω m) range at x = 0.0375. All these results show the potential of Z n 0.5 C o 0.25 C u 0.25 F e 1.9625 L a 0.0375 O 4 ferrite powders for X-band microwave applications. Image 1 • Zn 0.5 Co 0.25 Cu 0.25 Fe 2-x La x O 4 ferrite powders via simple sol-gel auto-combustion. • Crystallite size and lattice constant decrease with increasing La3+ cations. • Optical band gap energies and DC resistivity have minimum values at x = 0.0375. • The ferroelectric nature of all the samples was confirmed using the P-E loop. • Maximum magnetization saturation was observed at x = 0.0375. [ABSTRACT FROM AUTHOR]

Tertiary Cu 0.25 Ni 0.15 M 0.25 Co 0.35 La 0.15 Fe 1.85 O 4 (M = Mg 2+ , Mn 2+ , and Cd 2+ ) spinel ferrites powders were prepared using the cost-effective sol-gel auto combustion route. The lattice parameters, absorption and vibrational bands, energy band gap, AC conductivity, and dielectric loss of the as-prepared ferrites were all measured. The Cd2+ doped ferrite has a minimum crystallite size (D) of 50.9 nm, which is smaller compared to Mg2+ and Mn2+ doped ferrites. Furthermore, the X-ray diffraction (XRD), as well as Fourier transform infrared radiation (FTIR) and Raman analysis confirmed the doping of Mg2+, Mn2+, and Cd2+ ions on their respective lattice sites. The resistivity of the divalent ions (Mg2+, Mn2+, and Cd2+) doped ferrites decreased in the para region and increased in the ferro region as the temperature increased. Moreover, the resistivity of the Cd2+ doped ferrite was smaller when compared to the ferrites doped with Mg2+ and Mn2+ ions. From Arrhenius plots, the minimum activation energy (Δ E) 0.8671 eV was observed for Cd2+ doped ferrites. The Cd2+ substituted ferrite also has the smallest AC conductivity and dielectric loss compared to Mg2+ and Mn2+ substituted ferrites. The coercivity and saturation magnetization were 136.41 Oe and 92.29 emu/g for the Cd2+ doped ferrite, respectively. These results suggest that the Cd2+ doped ferrite material could be used in high-frequency and high-power applications. • The Cu 0.25 Ni 0.15 M 0.25 Co 0.35 La 0.15 Fe 1.85 O 4 (M = Mg 2+ , Mn 2+ , and Cd 2+ ) spinel ferrites were prepared. • Minimum activation energy and maximum optical bandgap energy were observed for Cd-CNCL ferrite. • The minimum coercivity and maximum initial permeability were found for Cd-doped CNCL ferrite. • The Cd2+ doped CNCL ferrite exhibits minimum dielectric losses. • The Cd2+ doped CNCL ferrite is best for high-frequency and high-power applications. [ABSTRACT FROM AUTHOR]