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The impact of holmium (Ho) ions on lithium-rich spinel ferrites is studied through magnetic, morphological, and electrical transport properties. The X-ray photoelectron spectroscopy (XPS) analysis indicated the existence of all metal ions in the required valence state. Transmission electron microscopy (TEM) analysis exhibited nano-crystalline (∼50 nm) structures of these ferrites. The electrical resistivity measurements showed the higher resistivity values of the synthesized samples. The resistivity increased from 2.4 × 108 to 2.1 × 1010 Ω-cm with Ho inclusion, indicated an inverse relation with the size of grains. The Curie temperature (T c ) observed to decrease from 848 to 806 K with the incorporation of Ho 3+ ions. The activation energy (Δ E a ) noted to vary between 0.21 and 0.23 eV. The drift mobility (μ d) study revealed a decrease from 1.86x10 −12 to 6.14x10 −14 cm 2 V −1 s −1 by increasing Ho amount up to x = 0.06. A reduction in thermoelectric power (S) from - 143 to -95 μ.V/K by increase in Ho concentration confirmed the Fe replacement by Ho on octahedral B-sites. The ferromagnetic resonance (FMR) investigations indicated a drop in FMR line-broadening (ΔH) from 2491 to 2000 Oe by the increase of Ho concentration, making it beneficial to reduce microwave losses. A non-linear variation in the resonance field (H res) with the substitution of Ho was observed between 7359 to 7785 Oe. [ABSTRACT FROM AUTHOR]

In this study, the sol-gel autocombustion route was used to synthesize Cd-Zn-Cr ferrites/graphene nanoplatelets nanocomposites having chemical formula Cd 0.35 Zn 0.65 Cr 0.03 Fe 1.97 O 4 /GNP x (x= 0–5 wt%). Thermogravimetric examination (TGA) was utilized to estimate the annealing temperature of about 1173 K. The manufacturing of a mono-phase cubic spinel structure was verified through XRD data. The composites' lattice constant (a) and crystalline size (D) ranged from 8.43 Å to 8.47 Å and 29.66 nm to 38.32 nm, respectively. SEM micrographs revealed the nano-size particles attached to a sheet-like structure. The UV/Vis methodology revealed an energy band gap (E g) between 4.20 and 4.95 eV. Two probe DC electrical measurements (IV) indicated the increased electric conductivities of prepared nanocomposites. Room-temperature dielectric analysis has shown an increase in dielectric constant (ε′), AC conductivity (σ ac), and capacitance of the pellet (C p) by increasing the GNP concentration due to the conducting network. The dielectric constant, capacitance, and ac conductivity of the nanocomposites were found to be 2.57, 1.18×10−09 F, and 1.25×10−10 (Ω.cm)−1 for GNP=5.00 wt% as compared to 1.95, 6.63×10−10 F, and 3.09×10−11 (Ω.cm)−1 for GNP=0.00 wt%, respectively. These composites are useful as high-performance electrodes in charge storage devices at high frequencies. The saturation magnetization (M s) of the synthesized ferrites/GNP nanocomposites ranged from 4.1 to 11.5 emu/g, and the coercivity (H c) varied from 109 to 452 Oe. The demonstrated nanocomposites provide a strategy for designing high-efficiency electrode materials for supercapacitors. • CZCF/GNP nanocomposites were investigated for structural, magnetic, dielectric, and electrochemical properties. • SEM micrographs revealed the attachment of nano-sized ferrite particles attached to a sheet-like structure. • DC electrical measurements (IV) indicated the increased electric conductivity as a function of GNP content. • Both M s and H c showed a significant change by increasing the GNP concentration in the CZCF crystal matrix. • Enhanced capacitance and ac conductivity of CZCF/GNP nanocomposites suggest them for designing high-efficiency electrode materials for supercapacitors. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) strongly coupled nonideal plasma systems (SC-NIPSs) are modeled using equilibrium molecular dynamics (EMD) simulations. The dynamical structure factor (DSF) has been investigated under influence of varying wave vectors (k = 2π/L) at high Debye screening (κ) and varying Coulomb couplings (Γ) from nonideal phase to strongly coupled phase. New outcomes of dust DSF S(k,ω) indicate that the frequency of oscillation increases and amplitude decreases with an increase in Γ, respectively, for the SC-NIPSs. The present work shows that the amplitude of dust DSF slightly increases with increasing κ and N, and it also depends on variation of wave vectors. Our investigations demonstrate that the amplitude of oscillation of the dust DSF is changed and shape of spectrum switches from damped oscillation mode to sinusoidal mode with an increase in Γ. These modes of oscillation of dust DSF S(k,ω) shift to higher Γ with increasing κ and N. It has been revealed that the fluctuating density S(k,ω) of dust more oscillates at high Γ and midway value of κ, but this oscillation is less pronounced at high N and κ. The reported simulation data are found to have more precise and well-organized than that of earlier known numerical outcomes and it provides reasonable EMD outcomes with suitable varying N at high screening and large values of Γ than earlier numerical results. [ABSTRACT FROM AUTHOR]

Ho-substituted Li–Ni ferrites with composition L i 1.2 Ni 0.4 Ho x Fe 2- x O 4 ; 0≤ x ≤ 0.15 were synthesized by a self-ignited sol-gel process. An annealing temperature of 950 °C is estimated via thermal-gravimetric (TGA) analysis. X-ray diffraction (XRD) scans have confirmed the formation of the ferrite phase with a spinel structure in all samples. Substitution of Ho ions on the B-site significantly reduced the porosity from 38 -to 23% and the crystallite size from 23.4 -to 21.7 nm. Microstructural analysis revealed a denser structure with an increase in Ho content. Dielectric results showed that both the dielectric loss and dielectric constant depict a nonlinear variation with the addition of Ho. Complex impedance behavior with a single semicircle for all samples suggests the predominant effect of the grain boundary mechanism. The substitution of Ho ions in place of Fe ions significantly decreased the electrical conductivity. The anisotropic Ho3+ ions reinforce the L-S coupling which consequently enhanced the coercive force from 145 -to 389 Oe, and thus the anisotropy constant. [ABSTRACT FROM AUTHOR]

We investigate here the effect of holmium on Li–Co nano-ferrites to elaborate the surface morphology, dynamic magnetic and electrical transport properties. The transmission electron microscopy (TEM) technique was employed to examine the microstructure and grain size distribution. TEM analysis confirmed the nanocrystalline nature (~50 nm) of the prepared materials. X-ray photoelectron spectroscopy (XPS) experiment results verify the presence of all metal ions with the required valences. Ferromagnetic resonance (FMR) analysis revealed the need for a dense microstructure to cut down the microwave losses. FMR line width was observed to reduce from 2757 -to 1676 Oe except for x = 0.12 by the substitution of Ho ions which correspond to low microwave losses. The dc resistivity results show that high resistivity values are associated with smaller grains of the samples and vice versa. Resistivity values are found to increase from 3.66 × 108 -to 5.31 × 108 Ω-cm by increasing the Ho addition. Seebeck experiment revealed n-type conduction. Together with showing the nature of charge carriers, a decrease in the Seebeck coefficient with increasing Ho ensured the replacement of Fe ions by Ho ions on B-sites. [ABSTRACT FROM AUTHOR]

The substitution of rare earth ions is a novel approach to vary the dynamic magnetic properties of soft ferrites to such an extent that its electrical properties and ferromagnetic resonance (FMR) response can be set over a broad frequency range. In this work, a complete transmission electron microscopy (TEM), scanning electron microscopy (SEM), ferromagnetic resonance spectroscopy (FMR), X-ray photoelectron spectroscopy (XPS), and current-voltage (I-V) analysis of holmium (Ho) substituted lithium-nickel soft ferrites with composition Li 1.2 Ni 0.4 Fe 2−x Ho x O 4 (x = 0, 0.03, 0.06, 0.09, 0.12, and 0.15) is carried out. TEM analysis reveals a spherical shape distribution of nanoparticles with a particle size of ∼ 50 nm. FMR study is carried out to check the role of Ho addition on magnetic energy losses, FMR line position, and shape. The shift in FMR line shape is mainly attributed to the anisotropy contribution, relaxation processes, and ferromagnetic interactions between the magnetic nanoparticles. XPS experiments confirm the presence of all compositional elements along their valence states. The Ho substitution increased the electrical resistivity, whereas the damping of A-B exchange interactions resulted in a decline of Curie temperature (T c), which is required for high-frequency power applications. • TEM study of Ho-doped Li-Ni ferrites revealed an average particle size of ∼ 50 nm. • XPS experiments confirm the presence of all compositional elements along their valence states. • Enhanced electrical resistivity and a decline in Curie temperature as a function of Ho were observed. • FMR losses were reduced by replacing the Fe ions with Ho ions required for high-frequency power applications. [ABSTRACT FROM AUTHOR]

Equilibrium molecular dynamics (EMD) simulations have been performed to investigate the structural analysis and thermal conductivity (λ) of semiconducting (8,0) and metallic (12,0) zigzag single-walled carbon nanotubes (SWCNTs) for varying ±γ(%) strains. For the first time, the present outcomes provide valuable insights into the relationship between the structural properties of zigzag SWCNTs and corresponding thermal behavior, which is essential for the development of high-performance nanocomposites. The radial distribution function (RDF) has been employed to assess the buckling and deformation understandings of the (8,0) and (12,0) SWCNTs for a wide range of temperature T(K) and varying ±γ(%) strains. The visualization of SWCNTs shows that the earlier buckling and deformation processes are observed for semiconducting SWCNTs as compared to metallic SWCNTs for high T(K) and it also evident through an abrupt increase in RDF peaks. The RDF and visualization analyses demonstrate that the (8,0) SWCNTs can more tunable under compressive than tensile strains, however, the (12,0) zigzag SWCNTs indicate an opposite trend and may tolerate more tensile than compressive strains. Investigations show that the tunable domain of ±γ(%) strains decreases from (-10%≤ γ ≤+19%) to (-5%≤ γ ≤+10%) for (8,0) SWCNTs and the buckling process shifts to lower ±γ(%) for (12,0) SWCNTs with increasing T(K). For intermediate-high T(K), the λ(T) of (12,0) SWCNTs is high but the (8,0) SWCNTs show certainly high λ(T) for low T(K). The present λ(T, ±γ) data are in reasonable agreement with parts of previous NEMD, GK-HNEMD data and experimental investigations with simulation results generally under predicting the λ(T, ±γ) by the ∼1% to ∼20%, regardless of the ±γ(%) strains, depending on T(K). Our simulation data significantly expand the strain range to -10% ≤ γ ≤ +19% for both zigzag SWCNTs, depending on temperature T(K). This extension of the range aims to establish a tunable regime and delve into the intrinsic characteristics of zigzag SWCNTs, building upon previous work. [ABSTRACT FROM AUTHOR]

We report the dopant- and size-dependent variations in high-frequency magnetic and electrical transport properties of Ho-substituted Li-Mn polycrystalline ferrites. Thermal stability and phase identification were confirmed by thermal gravimetric analysis and X-ray diffraction experiments. The overall average crystallite size decreased from 29.6 to 17.5 nm, whereas the bulk density increased from 3.47 to 4.29 g/cm 3 with increasing Ho content. Ferromagnetic resonance (FMR) measurements at the X-band revealed significant shifts in FMR linewidths and resonance positions as a function of composition. Both, FMR linewidth and porosity, were found to decrease with the systematic addition of Ho from 2538 to 2359 Oe and from 26% to 15.4%, respectively. The substitution of Ho 3+ for Fe 3+ reduced the net magnetization of the spinel lattice from 53 to 41 emu/g. Electrical measurements revealed that the resistivity is higher in samples with smaller grains possessing a greater number of thin insulating grain boundaries. The activation energy ∆ E required for hopping increases from 0.09 to 0.16 eV with Ho addition, which may be well explained by the increase in resistivity. The substitution of Ho 3+ for Fe 3+ causes a decrease in Curie temperature T c due to the damping of A-B exchange interactions. [ABSTRACT FROM AUTHOR]

In the present study, the impact of holmium (Ho) substitution on structural, spectral, dielectric and magnetic behavior of Li 1.2 Zn 0.4 Ho x Fe 2−x O 4 (0.00 ≤ x ≤ 0.15) ferrites was investigated. The development of spinel phase and structural changes induced by Ho doping were confirmed by X-ray diffraction. The accommodation of Ho ions into spinel lattice was restricted for x ≥ 0.06 as indicated by ortho phase (HoFeO 3 ) traces. The decrease in lattice parameter ( a ) was attributed to the segregation of Ho ions on grain boundaries. FTIR spectra featured two intrinsic vibrational bands v 1 (617 cm −1 ) and v 2 (488 cm −1 ) for x = 0 due to tetrahedral and octahedral vibrations respectively. The compositional dependence of force constants and bond lengths has explained on the basis of cations distribution and oxygen-cation bond distances of respective sites. The addition of Ho ions decreased the saturation magnetization and optimized the coercivity from 59 to 335 Oe, proposing these ferrites for magnetic recording media. Dielectric results for the entire range of frequency (1 MHz to 3 GHz) revealed that ac conductivity increased from 3.5 × 10 5 to 1.8 × 10 6 (Ω-cm) −1 up to x = 0.09 and then it decreased slightly for x = 0.12. The effective contribution of grain-interior mechanism to dielectric behavior was confirmed by complex impedance study. The results of dielectric studies displayed that Ho doped lithium ferrites are suitable low loss potential materials for high frequency based applications. [ABSTRACT FROM AUTHOR]

A comprehensive study on structural, spectral, magnetic and dielectric properties of holmium substituted (Ho 3+ ) lithium ferrites; Li 1.2 Co 0.4 Ho x Fe 2−x O 4 (x = 0.00–0.15) synthesized via auto-citric combustion route has been carried out. The annealing temperature essential for complete decomposition of precipitates and spinel phase formation was found around 950 °C which was estimated from thermo-gravimetric analysis (TGA). The development of face centered cubic (FCC) spinel structure was confirmed from X-ray diffraction (XRD) analysis. However, the traces of an ortho phase (HoFeO 3 ) were appeared for x ≥ 0.06 indicating the solubility limit of Ho 3+ ions. The lattice constant ′ a′ increased from 8.351 to 8.360 Å upon Ho addition up to x = 0.06 and it decreased thereafter from 8.360 to 8.352 Å. This decrease in lattice constant was attributed to the secondary phase formation revealing segregation of Ho 3+ ions at grain boundaries. The porosity was found to decrease from 44 to 23% by the inclusion of Ho 3+ ions. Fourier transform infrared spectra (FTIR) exhibited tetrahedral ( v 1 ) and octahedral ( v 2 ) intrinsic vibrational bands at 627 cm −1 and 479 cm −1 respectively and these bands revealed a shift with increasing Ho concentration. The variations in force constants ( K o and K t ) were calculated and discussed with the tetrahedral (r A ) and octahedral (r B ) bond length trends. The dielectric parameters have been investigated as a function of composition and frequency. The systematic addition of Ho gradually increased the ac conductivity from 8.97 × 10 3 to 5.56 × 10 4 (Ω-cm) −1 up to x = 0.12 and it subsequently decreased for x = 0.15. The complex impedance examination (Cole-Cole plots) confirmed a grain-interior phenomenon, effectively contributing to the dielectric properties. The coercivity was enhanced while the saturation magnetization (Ms) was lessened by the incorporation of Ho 3+ ions. The maximum value of coercivity (706 Oe) was obtained for Li 1.2 Co 0.4 Ho 0.12 Fe 1.88 O 4 . The improved coercivity may suggest their utilization in perpendicular recording media applications. [ABSTRACT FROM AUTHOR]

We present the effects of size and oxygen defects on electrical and optical properties of nano crystalline bismuth ferrite (BiFeO 3 ) with rhombohedral symmetry synthesized by solution evaporation method. The effects of oxygen vacancies on the behavior of system have been studied by annealing all samples under two different environments, air and oxygen. Single phase crystal structure was confirmed by X-Ray diffraction (XRD). The crystalline size calculated by Scherrer's formula falls in the range of 11–21 nm for air and 20–29 nm in case of oxygen annealing atmosphere. The crystalline size was confirmed by Transmission electron microscope (TEM). Dielectric response reveals that both dielectric constant and dissipation factor (tanδ) decrease with increase of frequency without depicting any peak. Optical studies showed that the system possesses an indirect energy gap whose value increases with increasing particle size. There is an evidence for the presence of intra band states in this system arising from defect states. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) thermal conductivity of strongly coupled dusty plasmas, taking into account the polarization effect of dust particles, has been investigated through homogenous nonequilibrium molecular dynamics (HNEMD) simulations. Thermal conductivity (λ), in the limit of varying polarization values, is reported over a appropriate domain of plasma states (Γ, κ), coupling (dipole–dipole) factor (Γd) and constant external force field (F*). New results of polarized λ show that the effect of polarization definitely decreases the λ at low-intermediate to large Γ where it was earlier shown to have high value of λ without considering polarization effects. The obtained results for polarized λ decrease with increasing system size (N) and Coulomb coupling (Γ) at varying polarization values (Γd) but within statistical limits, however, polarized λ becomes nearly constant at higher N. The simple temperature scaling law has been checked for variations of normalized (Einstein) thermal conductivity with polarization effects. The current HNEMD outcomes under varying polarization values and constant force (external) field strength are reasonable well matched with earlier known simulation data of equilibrium, nonequilibrium molecular dynamics simulations and experimental data. It has been revealed that the present HNEMD simulations extended the range of polarization values up to 1 ≤ Γd ≤ 150 in order to maintain the range of linearity at F* (≡ 0.2) and to illuminate the nature of polarized system of 2D strongly coupled dusty plasmas. [ABSTRACT FROM AUTHOR]

We have compared the multiferroic behavior in different-sized BiFeO nanoparticles (11-29 nm) prepared by a solution evaporation method. The effects of oxygen vacancies on the behavior of phase pure BiFeO have been studied for particles prepared under two different annealing environments, air and oxygen. We find that BiFeO nanoparticles show weak ferromagnetism at room temperature which increases with decreasing particle size. However, the effects are determined not to be related to the presence of more oxygen vacancies, since oxygen annealing increases the magnetic moment in this system. In dielectric studies, we observe clear evidence for magnetoelectric coupling with the imaginary part of dielectric constant exhibiting a clear anomaly around the magnetic transition temperature ( T ~ 560 K). In high temperature resistivity measurements insulating and activated resistivity behavior is observed with the activation energies being lower for T < T. The increased ferromagnetism in smaller particles is explained in terms of suppression of the antiferromagnetic spin spiral whereas oxygen annealing actually leads in our case to an improvement of the crystallinity. [ABSTRACT FROM AUTHOR]

The space-time correlation function has been obtained in strongly coupled dusty plasmas (SCDPs) using equilibrium molecular dynamics (EMD) simulations. The simulated results for three-dimensional (3D) SCDPs with suitable normalization are computed over a wide domain of plasma parameters (Γ, κ) in a microcanonical ensemble. The EMD simulations indicate that different modes of propagated wave in SCDPs are analyzed for four different values of wave number (k). New investigations of normalized longitudinal current correlation function CL(k, t) show that the amplitude of oscillation and frequency of propagated modes increase with an increase in k. The obtained results for longitudinal modes of oscillation indicate that the dust particles remain in damping behavior at the low Γ, damped oscillation with decreasing amplitude inside decaying exponential envelope at intermediate Г, and sinusoidal oscillation at high Г, depending on κ. The system size (N) does not significantly affect the propagated modes of oscillation, while the periodic oscillation shifts toward higher Γ with increasing N and κ. The computations show that normalized longitudinal CL(k, t) current correlation particularly depend on Coulomb coupling (Γ), Debye screening (κ), and wave number (k). In our simulations, the frequency and the amplitude of oscillation of the dust particles decrease with an increment of κ and system size (N), but the frequency increases and the amplitude decreases with increasing Γ, as expected. It has been demonstrated that the EMD method is used to study the different propagated modes in dusty plasma systems and can be used to predict the damping behavior, damped oscillation, and periodic phenomena in 3D strongly coupled SCDPs. [ABSTRACT FROM AUTHOR]

Hybrid supercapacitors are energy storage technology offering higher power and energy density as compared to capacitors and batteries. Cobalt-doped manganese oxide (Co@MnO2) was synthesized using an easy and affordable sol–gel process and measured the electrochemical properties. A value of the specific capacity of 1141.42 Cg−1 was obtained which was larger in comparison to the reference sample (MnO2 = 673.79 Cg−1). The value of the specific capacitance was achieved 1902 Fg−1. To design a hybrid supercapacitor device, Co@MnO2 was used as the positive electrode and the activated carbon was employed as the negative electrode in two-electrode assembly. According to calculations, the measured value of the specific capacitance of Co@MnO2 was 713.25 Fg−1. The charge storage mechanism is supported with the help of Randles–Ševčík and Dunn's models. The estimated value of energy and power densities were 3200 Wh kg−1 and 24 Wkg−1, respectively. The stability of this device was checked by putting it to 1000 charging and discharging cycles, and it retained 86% of its initial capacity. Our result provides a platform for enhancing the functionality of energy storage systems. [ABSTRACT FROM AUTHOR]

A systematic investigation on structural, electronic, elastic, mechanical and optical properties of novel 1:1 stoichiometric rare-earth HoX (X = Pd, Ag and Cd) intermetallic compounds has been made viaab-initio density functional theory-based linearized augmented plane wave method as coded in wien2k. An outline of local density approximation and generalized gradient approximation have been employed. Structural optimization established the stable CsCl-type cubic structure of HoX (X = Pd , Ag and Cd) compounds. The determined crystal structure stability, compressibility and fracture strength of compounds are enhanced with X in the order HoPd > HoAg > HoCd . The interlacing electron dispersion curves at Fermi-level in band structure and density of states substantiate the metallic nature of compounds. The splitting gap between the lower and upper valence bands monotonously becomes narrower with the substitution of heavier core-element (Pd → Ag → Cd) . The mechanical constants i.e., bulk modulus (B), Young’s modulus (E), shear modulus ( G H ), Pugh’s ratio (B / G H) , Poisson’s ratio (v) and anisotropic factor (A) have been calculated to corroborate the mechanical properties of compounds. The cationic nature of Ho-atoms and anionic nature of X-atoms has been evaluated through the effective charge (Q ∗ ) computations. The observed peaks in the low energy region of optical conductivity spectra attribute the intra-band, while the high energy structures are associated with inter-band transitions in HoX (X = Pd, Ag and Cd) compounds. The bond order calculations demonstrate the highest strength of HoCd compound among the herein studied compounds. [ABSTRACT FROM AUTHOR]

The present study investigates the photocatalytic activity of NiCoPrFe 2 O 4 and Cd-NiCoPrFe 2 O 4 synthesized by the self-ignition sol-gel process. NiCoPrFe 2 O 4 @CNTs was prepared via ultrasonication approach. Methyl violet was used as a dye to examine the photodegradation activities of synthesized photocatalysts under visible light. The spinel crystalline structure is confirmed by XRD. The morphology of the as prepared samples was observed via scanning electron microscopy. NiCoPrFe 2 O 4 , Cd-NiCoPrFe 2 O 4 , and NiCoPrFe 2 O 4 @CNTs showed 55.46%, 78.29%, and 85.96% percentage degradation of methyl violet respectively. The photocatalytic performance of CNT based nanocomposite is found to be increased due to the enhanced charge separation property of CNT. • The sol-gel method was used for the preparation of NiCoPrFe2O4. • XRD and FTIR corroborate the structure and composition of elemental features. • SEM analysis confirms the morphology of the material. • NiCoPrFe2O4@CNT composite had shown excellent result is the photo-degradation of methyl violet. [ABSTRACT FROM AUTHOR]

Supercapattery is an energy storage device which shows high power and energy densities compared to supercapacitors and batteries. A simple and cost‐effective sol‐gel method was used to synthesize the aluminium‐doped cobalt oxide (Al‐Co3O4). The structural, morphological and composition analyses were investigated using X‐ray diffraction (XRD), scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS). Further, Brunauer‐Emmett‐Teller (BET) calculations were performed, which showed an enhancement in surface area. The specific capacity of the Al‐doped sample was increased up to 708 C/g compared to the reference sample (Co3O4=420 C/g). A supercapattery device was designed by using the activated carbon as a negative electrode and the Al‐Co3O4 as the positive electrode in two electrode assemblies. The estimated value of the specific capacity of Al‐Co3O4 was 189 C/g. Furthermore, the obtained energy and power density values were 42 Wh/kg and 2080 W/kg, respectively. To investigate the stability, this device was subjected to 5000 charging/discharging cycles that maintained 90 % of its initial capacity. Our findings provide a foundation for improving the performance of energy storage devices. [ABSTRACT FROM AUTHOR]

Nano-sized Zr-Co doped nickel ferrites with nominal composition, NiZr x Co x Fe 2-2x O 4 ( x =0.0, 0.2, 0.4, 0.6, 0.8) were synthesized using the micro-emulsion route. The structural elucidation of the synthesized materials was carried out by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The XRD analysis confirmed face centered cubic (FCC) structure of all compositions of NiZr x Co x Fe 2-2x O 4 nanocrystallites. Crystallite size was calculated by Scherrer's formula found in the range 10–15 nm. The variation in lattice parameter as determined by XRD data agreed with size variation of host (Fe 3+ ) and guest (Zr 4+ and Co 2+ ) cations. FTIR spectra of doped NiFe 2 O 4 exhibited the typical octahedral bands at 528.4 cm −1 which is the characteristic feature of spinel structure of spinel ferrites. The characterized spinel NiZr x Co x Fe 2-2x O 4 nano-ferrites were evaluated for their potential applications by magnetic hysteresis loops and dielectric measurements. The value of saturation magnetization ( M s ) decreased from 47.9 to 13.09 emu/g up to x =0.8 with ups and downs fluctuations in between x=0.0 to x=0.8. The high values of Ms of some compositions predicted the potential applications in high density perpendicular recording media and microwave devices. The frequency dependent behavior of permittivity (ε') is recorded and discussed with the help of hopping mechanism of both holes and electrons. The dielectric and magnetic data of NiZr x Co x Fe 2-2x O 4 nano-ferrites suggested the potential applications of these ferrite nanoparticles in high frequency and magnetic data storage devices fabrication. [ABSTRACT FROM AUTHOR]

• sol–gel method was for Sr 1-x Bi x Fe 12-y Co y O 19 hexaferrites. • Crystalline size is found in the range of 20 to 28 nm. • The bond length decreases due to Fe/Co-O with Bi-Co substitution. • SEM analysis confirmed hexagonal structure of all prepared samples. • High quality factor (22000) suggests their utility in high-frequency applications. Bi and Co-substituted strontium (SrFe 12 O 19) hexaferrites were synthesized using the auto-combustion sol–gel method. The structural, Rietveld refinement, microstructural, spectroscopic, and dielectric characterizations were analyzed with X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and Dielectric analysis, respectively. The XRD investigation of Sr 1-x Bi x Fe 12-y Co y O 19 with (x = 0–0.5, y = 0–1.0) confirmed the single phase of M−type hexagonal ferrites. The change in the value of lattice constant 'a' in between 5.87 and 5.95 and 'c' 22.07 to 23.81 to be noted. The crystallite size of prepared specimens was determined in (20–29) nm range. The specific stretching vibrations in the FTIR results approves (Fe/Co-O and Bi-O) at three different positions 437.59, 549.94, and 587.53 cm−1. The existence of these band from 437 to 588 cm−1 confirmed the hexagonal structure of these ferrites. The force constants at octahedral sites increased from 1.75 to 2.02 (Dyne cm−1) x 105 and shows insignificant behavior at tetrahedral sites in between (3.33–3.54) Dyne cm−1 x 105 with Bi-Co substitution. The first band 582 cm−1 (ʋ 1), is due to the maximum restoring force and vibrations at the tetrahedral site. The second band at a lower wavenumber of ∼ 402 cm−1 (ʋ 2) is due to the vibrations at the octahedral site. The microstructure of all synthesized samples of M−type hexagonal ferrites confirmed using the SEM analysis. The dielectric measurements in 0 to 3 GHZ frequency was done and effect of Bi-Co has been observed. The dielectric constant of all specimens shows the increasing trend from 1.5 GHz to 2.5 GHz with the frequency of the applied AC field. A slight increase was observed in the AC conductivity of these ferrites with the increasing concentration of Bi and Co ions. [ABSTRACT FROM AUTHOR]

Cadmium ferrites belong to normal spinel ferrites, and they exhibit interesting electrical, magnetic, and optical properties. The pure and cerium-doped cadmium ferrites CdFe2−xCexO4 (x = 0.0, 0.125, 0.250, 0.375, 0.5) were synthesized by a chemical co-precipitating technique using sodium hydroxide as a co-precipitating agent. The structures and phase purity of fabricated nanomaterials were analyzed by X-ray diffraction (XRD). The crystallite size for all the prepared nanomaterials was in the range of 28–46 nm. The lattice constant and unit cell volume were found to decrease with the increasing concentration of Cerium, which was confirmed by the peak shift in the XRD pattern. The X-ray density for all nano ferrites increased with the enhancement of cerium composition. The resistivity of the nanomaterials has random behavior with the enhancement of cerium composition for a temperature, but the value of resistivity at x = 0.125 has the lowest value and at x = 0.375 has the highest value for almost all temperatures. For specific concentrations, a decreasing trend of resistivity of fabricated materials was found with an increment of temperature. The activation energies were also calculated, and it increased for x = 0.125 and then decreased for all the nanomaterials. For the confirmation of the M–O bonds, FTIR analysis of all the nano ferrites was also performed. The analysis shows a higher frequency absorption band in the range of 531.24–534.84 cm−1. This absorption band confirms that metal oxides are formed in all the synthesized nanoparticles. [ABSTRACT FROM AUTHOR]

In this research work we have synthesized copper sulfide (Cu2−xS) nanostructures by the hydrothermal method. The post-sulfurization was performed by using tube furnace to reduce sulfur deficiency and to minimize impurities present in the crystal-lattice. The samples were synthesized by various pH values of precursor solution. The samples were characterized by XRD, RAMAN spectroscopy, SEM, Hall measurements and Seebeck effect. XRD analysis revealed the formation of hexagonal covellite (CuS) and chalcocite (Cu2S) phases of copper sulfide. Despite these phases XRD data also showed the dominating hexagonal digenite (Cu1.8S) phase of copper sulfide. We observed a decreasing trend in average crystalline size with the increasing pH values of the samples from the XRD data. We have found maximum average crystalline size of 39.1679 nm at pH value of 4. The formation of LO mode of hexagonal covellite phase of copper sulfide was observed from RAMAN analysis. The SEM images revealed the formation of flower-like nanostructures at the lowest pH value. It strengthened our argument that the crystallinity of nanostructures is inversely proportional to the pH value. We have achieved maximum values of Seebeck coefficient and conductivity at room temperature as 73.920 µV/K and 0.909 S/cm, respectively. The Seebeck coefficient and conductivity graphs showed an increasing trend due to the energy filtering effect in mesoporous structure. The maximum value of power factor was 4.91 × 10–7 Wm−1 K−2. [ABSTRACT FROM AUTHOR]

In this report, Mg(0.6)Zn(0.4)Fe2O4 (MZF) and CuxMg(0.6)Zn(0.4)Fe2O4 (CMZF) where (x = 0.2) were synthesized via sol–gel method. The composite of CuxMg(0.6)Zn(0.4)Fe2O4 with reduced graphene oxide (CuxMg(0.6)Zn(0.4)Fe2O4@rGO) was fabricated by wet chemical approach to get over the adverse impacts of toxic dyes and pathogenic bacterial strains. The rGO possesses high stability, larger surface area and an enhanced ability for electron transport during photocatalysis. X-ray diffraction, Scanning electron microscopy, Fourier transform infrared spectroscopy, Mott Schottky and UV–Visible spectroscopy were used to analyze the physiochemical properties of manufactured materials. Methylene blue (MB) and benzoic acid (BA) degradation was performed under the visible light of the Xenon lamp. The photocatalytic activity of MB exhibited degradation efficiency by MZF, CMZF, and CMZF@rGO was 16.67%, 42.72% and 76.19% respectively and degradation of BA by MZF, CMZF, and CMZF@rGO was 26.92%, 44.44% and 60.42% respectively. The composite (CMZF@rGO) exhibited the best degradation efficiency than bare and doped materials (MZF and CMZF) due to the greater surface area. As surface area increased, the e−/h+ pair recombination rate decreased. Therefore, the photocatalytic efficiency of the material enhanced. It is examined, CMZF@rGO has potential applications in the photocatalytic degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

The plethora of properties associated with half Heusler compounds has made them apposite materials for functional applications significantly in thermoelectrics, solar harvesting, semiconducting and spintronics. The current study invested the exertions in unveiling the details of physical properties of LiXBe (X = N, P) compounds using DFT based VASP and WIEN2k codes considering PBE-GGA and TB-mBJ exchange correlation functionals. Titled compounds successfully assured the stability checks regarding energetic, lattice dynamic and mechanical. By means of electronic structure calculations, TB-mBJ functional disclosed the precise band gaps of 6.912 and 2.340 eV for LiNBe and LiPBe compounds respectively. Fat-band character analysis and partial charge density distributions in HOMO and LUMO orbitals revealed the governess of band edges around Fermi-level by homo-site (N- 2p & N- 2s) states in LiNBe and hetero-site (P- 2p & Li- 2s) states in LiPBe compound. The COHP examination and bond order characteristics evidenced comparatively strongest bonding interactions of X–Be than Li–Be bonding pair. The calculated opto-electronic properties; complex dielectric function, optical conductivity, loss function and refractive index have been discussed with substantial details. Physio-mechanical parameters and mechanical anisotropy have been comprehensibly elaborated. [Display omitted] • Investigation of Physical properties of LiXBe (X = N, P) compounds via DFT. • LiXBe (X = N, P) found structurally, lattice dynamically and mechanically stable. • TB-mBJ functional disclosed the precise bandgaps of LiXBe (X = N, P) compounds. • LiNBe compound propose bandgap engineering via solo-site substitution/doping. • LiPBe compound could be promoted for transparent conductor's applications. [ABSTRACT FROM AUTHOR]

In the present study, with the aid of the ultrasonication route the copper-doped cobalt chromium ferrite with graphitic carbon nitride (CoCrCuFe 2 O 4 @gCN, CCrCuFO@gCN) was prepared whereas the cobalt-chromium ferrite (CoCrFe 2 O 4 , CCrFO) and copper doped cobalt chromium ferrite (CoCrCuFe 2 O 4 , CCrCuFO) were synthesized via sol-gel approach. The gCN has a vast surface area, better stability, and a higher capability for the transfer of electrons during photocatalysis. Prepared products were characterized by several standard techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV–Vis spectroscopy measurements (UV–Vis). The crystallite size of CCrFO and CCrCuFO were 16.3 nm and 15.8 nm respectively calculated by Debye Scherer formula. Under sunlight, Crystal violet, Congo red, Methyl orange, Methyl blue, and Benzoic acid were degraded. Under the same conditions, the CoCrCuFe 2 O 4 @gCN exhibited 90.2 % degradation of Crystal violet, 90.1 % of Congo red, 92.2 % of Methyl orange, 91.1 % of Methyl blue, and 57.9 % of Benzoic acid. During the photo-degradation of pollutants, photoactive species like hydroxyl radicals, holes, and electrons were found to be the major contributors. The CCrCuFO@gCN composite showed higher photocatalytic degradation activity than pristine and doped materials due to its enhanced surface area. As the surface area of nanocatalysts increased, the recombining rate of electron/hole pair reduced, and hence the photocatalytic efficiency was boosted. The remarkable removal efficacy of CCrCuFO@gCN nanocomposite can be attributed to its large/massive surface area, 2D structure, and enhanced capacity to transport electrons of graphitic carbon nitride. For an efficient application in wastewater treatment, this work aims to encompass the new progress and new research directions of CCrCuFO@gCN under sunlight. • Simple facile route was adopted to prepare CoCrCuFe 2 O 4 @g-C 3 N 4 , a new photocatalyst. • Photodegradation of numerous organic effluents by CoCrCuFe 2 O 4 @g-C 3 N 4 was studied. • Mechanistic investigation of degradation has also been discussed. [ABSTRACT FROM AUTHOR]

In this work, Y 1 − x Pr x F e O 3 (0 ≤ x ≤ 0.16) ceramics were fabricated via the auto-combustion sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM) associated with EDS mapping, and Fourier transform infrared spectroscopy (FTIR) were employed for structural and morphology analysis. The substitution of praseodymium (Pr) modified the orthorhombic structure into a hexagonal structure. However, small traces of Fe 2 O 3 and Y 2 O 3 appeared in all samples. The lattice constant 'a' was increased from 3.523 to 5.530 Å upon substitution up-to x = 0.12, afterward this started to decrease from 5.530 to 5.529 Å. Pure orthorhombic YFeO 3 (o-YFeO 3) has cell volume 223.61 (Å3), while the cell volume of Pr substituted hexagonal YFeO 3 (h-YFeO 3) showed a decreasing trend (125.61–125.43 Å). Bulk density was thoroughly decreased from 5.009 to 4.634 (g/cm3) by increasing the Pr concentration. Frequency dependence of the dielectric behavior was investigated at room temperature in a comprehensive frequency range of 1 MHz ~ 3 GHz. SEM results exhibited the average grain size 149.28 nm, 66.78 nm, and 69.36 nm for the samples 0.00, 0.08, and 0.16, respectively. The identification of o-YFeO 3 was confirmed by two main absorption bands ν 1 (449.86 cm-1) and ν 2 (567.12 cm-1) and these bands indicate a clear shift upon the addition of Pr. The force constant of absorption bands at tetrahedral and octahedral sites showed increasing trend and this ranges from 1.633dyn/cm2x105 to 1.912dyn/cm2x105 and 2.818dyn/cm2x105 to 8.832dyn/cm2x105, respectively. The substitution of Pr significantly enhanced the dielectric constant. The shifting of peaks at higher frequencies demonstrates that an increase of dopant concentration resulted in the shifting of peaks that may follow the Maxwell-Wagner-Sillars polarization mechanism. Pr substituted YFeO 3 exhibited microwave frequency response in a range of 1.6 GHz–2.9 GHz which might be suitable for high-frequency applications. [ABSTRACT FROM AUTHOR]

A series of Cu-Co-substituted manganese ferrites (Mn1-xCuxFe2-yCoyO4; x = 0.0–0.1, y = 0.00–0.25) were synthesized via microemulsion method. The values of structural parameters, i.e., lattice constant and crystallite size, were increased with the inclusion of Co and Cu ions. FTIR studies revealed first band at 400–500 cm−1 and second band at 561–588 cm−1. The values of dielectric parameters have been increased with the increase of Cu and Co concentrations. The magnetic parameters, i.e., saturation magnetization (Ms), coercivity (Hc), and remanence (Mr), have been investigated from M-H loops. The values of Ms and Mr were observed to increase from 5.00 to 36.02 emu/g and from 4.6 to 13.2 emu/g, respectively. The value of coercivity had been decreased from 466 to 261 Oe. The increase in saturation magnetization as well as decrease in dielectric losses proposed that synthesized nanoferrites may be potential candidates for high frequency and microwave applications. [ABSTRACT FROM AUTHOR]

Co2+ and Mn2+ co-doped lithium spinel ferrites with the chemical composition Li 0.5 Fe 2.5-0.5x Co x Mn x O 4 (x = 0.0–0.5) were fabricated by micro-emulsion method. The spinel structure with face centered the cubic phase was confirmed from the XRD study. The lattice constant was found to increase first from 8.369 to 8.374 Å and then decreased up to 8.367 Å, as the substitution level increased, attributed to the formation of the secondary phases. The crystallite size of nano ferrites was found in the range of 47 to 37 nm. Substitution of Co2+ and Mn2+ significantly enhanced the density of prepared ferrites. FTIR studies revealed the appearance of the characteristic vibration bands of Li 0.5 Fe 2.5 O 4 between 550 and 650 cm−1 which were appreciably influenced by the concentration of Co2+ and Mn2+. The force constants showed an indirect variation with the bond lengths of A- and B -sites. The dielectric properties such as dielectric constant (εʹ), complex dielectric constant (εʹʹ) and tangent loss (tanδ) were analyzed between 1 MHz and 3 GHz. By increasing the frequency, εʹ, εʹʹ, and tanδ were decreased and have shown a dispersive behavior at higher frequencies due to the effect of space-charge polarization. The obtained low values of dielectric loss may refer these materials for applications in transformer cores and high-frequency devices. • Growth of Li0.5Fe2.5-0.5xCoxMnxO4 (x = 0.0–0.5) ferrites by micro-emulsion method. • The lattice constant was found to increase first from 8.369 to 8.374 Å and then decreased. • FTIR studies revealed characteristic vibration bands of Li0.5Fe2.5O4 between 550 and 650 cm-1. • The dielectric properties were analyzed between 1 MHz and 3 GHz. [ABSTRACT FROM AUTHOR]

Ni 0.5 Sn 0.5 Co x Mn x Fe 2−2x O 4 ferrites with x = 0.0–0.8 have been prepared by the micro-emulsion method, using CTAB as a surfactant material. X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR) and vibrational sample magnetometer (VSM) were used to investigate the effects of Co and Mn substitutions on cationic distribution, crystallite size, lattice constant, spectral, magnetic and dielectric properties. Lattice constant and crystallite size were found to increase from 7.4 to 9.25 Å and from 11.8 to 19.7 nm respectively with increasing substitution of Co and Mn ions. Saturation magnetization (M S ) gradually increased from 20.5 to 47.6 emu/g with increase in the value of x. However, Coercivity increased from 152.7 to 462.4 Oe up to x = 0.4 and then it decreased thereafter. The dielectric constant, complex dielectric constant and tan loss (tanδ) were observed to decrease with increase in frequency, depicting the semiconductor behavior of the ferrites. Dc resistivity was observed to decrease considerably upon addition of Co and Mn content. The outcome for the tunable magnetic properties and achieved modification of the synthesized nanocrystallites may be chosen for tremendous applications; such as miniaturized memory devices that are based on the energy storage principles and capacitive components. [ABSTRACT FROM AUTHOR]

CoTb 0.03 Fe 1.97 O 4 ferrite and poypyrrole (PPy) polymer nano composites were prepared by mixing the nano crystalline ferrite with poypyrrole (PPy) by following the solid state reaction synthesis route. The XRD patterns of CoTb 0.03 Fe 1.97 O 4 spinel ferrite powders and polymer (PPy) exhibited single phase spinel structure. The amorphous nature of PPy was evidenced by the broad peaks of XRD patterns. The surface morphology unfolded heterogeneous distribution in composites and ferrite. The grains in ferrite were spherical in shape with clear boundaries. The morphology was appreciably altered by the inclusion of ferrite contents. The higher activation energy and resistivity aroused due to blocking of conduction mechanism owing to nanoparticles embedded in the PPy matrix. A downfall in the dielectric loss of the composites is observed as the frequency of the applied field is increased. The incorporation of ferrite contents optimized the magnetic parameters of the composites. The enhanced coercivity (Hc) of these nanocomposites might be beneficial for memory devices. [ABSTRACT FROM AUTHOR]

Antiperovskites have gained huge interest due to their distinctive physical, chemical, and thermodynamic properties. They are electronically inverted perovskites that turned out to be a growing class of versatile materials, providing a dynamic and effective research field to materials scientists. The present work is designated to study significant physical properties of novel antiperovskites XCRh 3 (X = Cd, Ta, W, Re, Os, Ir, Pt, Au, Hg, Ce, Pr, Nd, Pm, Sm, Eu, Tb) using density functional theory based first-principles approach. This study includes the investigation of the structural, electronic, elastic, magnetic, and thermodynamic properties of the presented antiperovskites. Both the paramagnetic and ferromagnetic phases have been considered for computing the formation energy of compounds to elaborate the structural and mechanical stability. The spin-polarized electronic properties of ferromagnetic stable compounds demonstrated metallic features at the Fermi level in both spin versions. The mechanical parameters related to macroscopic properties, i.e., Young's modulus, Bulk modulus, shear modulus, tetragonal shear modulus, Poisson's ratio, Pugh's ratio, Cauchy's pressure, Zener anisotropic factor, lubrication factor, and compressibility factor have also been computed. The quasi-harmonic Debye model has been employed to analyze various important thermodynamic properties under a broad range of pressure (0–50 GPa) and temperature (0–1400 K). [ABSTRACT FROM AUTHOR]

• Sol-gel route was used to prepare Ba 3 Co 2-x Mg x Fe 24 O 41 hexaferrites. • The occupancy of Mg2+ ions at the octahedral site was altered by Fe3+ ions. • The dielectric permittivity was decreased by incorporating of Magnesium. • Cole – Cole plots revealed a single semi-circle. • Magnetic investigations unfolded ferrimagnetic nature of all samples. The Ba 3 Co 2-x Mg x Fe 24 O 41 hexaferrites were prepared by the sol–gel combustion route. The materials were annealed at 1350 °C and displayed the single-phase characteristics. X-ray density (D x) decreases owing to increasing Mg-concentration. Crystallite size was calculated with the help of Debye Scherrer's formula and found within the 17–18 nm range. Fourier transform infrared spectroscopy was used to determine the specific absorption peaks of hexagonal ferrites. It was executed in the region of 420–700 cm−1—the occupancy of Mg2+ ions at the octahedral site at delayed alternation of Fe3+ ions. As a result, the dielectric permittivity decreased. The grain boundary contribution was clearly seen in synthesized ferrites' cole plots. The cole – cole plots show a single semi-circle which reveals that grain boundaries play a significant role in the conduction process. Magnetic measurement indicated the ferrimagnetic behavior of all samples. [ABSTRACT FROM AUTHOR]

The substitution of Neodymium (Nd) in the cobalt - zinc (Co–Zn) ferrite was analyzed. The sol-gel technique was used to synthesize the se ceramic samples. The crystalline structural, molecular characterizations, and magnetic properties were analyzed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) experiments, and vibrating sample magnetometer (VSM) respectively. XRD patterns revealed the single-phase cubic spinel structure of the samples. Lattice p arameter varied from 8.41 to 8.38 Å with the inclusion of Nd concentration. The existence of two characteristic frequency bands in the range of 400–1400 cm−1 was confirmed by FTIR spectra. VSM measurements showed the magnetic behaviour at room temperature. The saturation magnetization was noted to decrease from 81 to 66 emu/g with increasing the Nd concentration. The sample having step size x = 0.025 revealed the highest coercivity and retentivity. Dielectric properties were studied and showed variation in dielectric constant, dielectric loss, ac conductivity, and energy dissipation (tangent loss) in the prepared material s. • Auto-citric combustion method was used to prepare Co0·6Zn0.4NdxFe2-xO4 ferrites. • The estimated value of constant lattice decreases upon increasing Nd ions. • Intrinsic vibrational bands revealed a shift with increasing the Nd content. • The porosity of the samples increased from 0.41 to 0.55. • Nd inclusion optimized saturation magnetization and coercivity. [ABSTRACT FROM AUTHOR]

A series of holmium (Ho) doped nanocrystalline Ni 0.7 Zn 0.3 Ho 2x Fe 2–2x O 4 ; 0.0≤x≤0.07 ferrite was synthesized using the conventional ceramic technique. The cubic spinel structure was confirmed by powder X-ray diffraction (XRD). The lattice parameter increases with increase in Ho content due to large ionic radius of Ho 3+ (0.901 Å) as compared to Fe 3+ (0.67 Å). Room temperature DC electrical resistivity and activation energy both increase with the increase of holmium contents. The saturation magnetization (M s ) decreased gradually from 78.92 to 54.17 emu/g due to holmium ions substitution in Ni-Zn ferrites. This decrease in M s is explained on the basis of redistribution of cations amongst the sites and weakening the A-B exchange interactions. An increase in electrical resistivity made this material suitable for its use in high frequency device applications. [ABSTRACT FROM AUTHOR]

Anti-perovskites have earned tremendous research interest in recent years, because of their copious unconventional physical, chemical and thermophysical properties. They are electronically inverted counterparts of perovskites' family and have become an emerging class of multifunctional materials, thus provides an enthusiastic and active research area to solid state scientists. Present work is devoted to explore some novel anti-perovskite materials using density functional theory based first-principles approach. The extant study includes the investigation of structural, electronic, elastic, mechanical, magnetic and thermophysical properties of XCNi 3 (X = Sc, Ti, V, Cr, Mn, Fe, Co and Cu) anti-perovskites. Structural and mechanical stability of studied compounds have been elaborated by computing formation energy and elastic constants respectively. The electronic properties of energetically and mechanically stable anti-perovskites have been found to be fully spin-polarized. Dependence of thermophysical properties under a broad range of temperature (0–1500 K) and pressure (0–100 GPa) have been discussed. Some of the anti-perovskites demonstrate intriguing properties and can be the potential candidates for magnetic applications e.g., magnetic sensors, spintronics, data storage devices and magnetic therapy. [Display omitted] • First-principles study of XCNi 3 (X = Sc, Ti, V, Cr, Mn, Fe, Co, Cu) anti-perovskites. • Computed formation energies preferred magnetic phase regarding structure stability. • Cauchy's pressure, Pugh's ratio and Poisson's ratio shown ductile nature of materials. • Spin-polarized band structures and density of states revealed the metallic features. • Thermophysical properties exhibited their dependence on temperature and pressure. [ABSTRACT FROM AUTHOR]

• Sol-gel technique was employed to synthesize Ba 4 Cu 2-x Ni x Fe 36 O 60 ferrites. • Cole-Cole plots markedly distinguished grain boundary contribution. • Coercivity (H c) increased (1844.44–2946.83 Oe) by increasing Ni contents. • The squareness ratio (0.471–0.450) revealed single magnetic domain. • The results suggest their potential use in high-frequency applications. This paper reports the impacts of nickel substitution on dielectric, magnetic, and structural characteristics of Ba 4 Cu 2-x Ni x Fe 36 O 60 hexaferrites prepared via the sol–gel method. The sample was annealed for 5 h at 1200 °C. The crystalline structure, magnetic and dielectric features were examined by X-ray diffraction, vibrating sample magnetometer, and impedance analyzer individually. The specific absorption bands of hexagonal ferrites were identified by FTIR spectroscopy and in the 420–600 cm−1 range. M−H loops of samples were determined to examine the magnetic properties of synthesized materials. Magnetic measurement shows that samples exhibit ferrimagnetic behavior at room temperature. The magnetic properties are described in cation distribution and grain size effect. Dielectric properties of the samples were observed in the frequency range (1–3 GHz). Cole-Cole graphs of prepared materials revealed the influence of grain boundaries. A single semi-circle in the impedance Cole-Cole plots approves a special part of grain boundaries in the conduction process. Dielectric properties are affected by the electron hopping mechanism between Fe2+ and Fe3+ ions. These performances expose that these nanomaterials are appropriate for high-frequency applications. [ABSTRACT FROM AUTHOR]

Dy–Ni substituted Mn 1-x Ni x Fe 2-y Dy y O 4 (x = 0.0–0.1 and y = 0.0–0.2) soft magnetic oxides were synthesized using a size controlled micro-emulsion method. X-ray diffraction (XRD) analysis was employed to confirm the spinel structure of synthesized ferrites. Crystallite size was found to decrease (33-22 nm) while lattice constant was increased (8.58–8.63 Å) by increasing dopants content. FTIR bands observed in the range 500–600 cm−1 is the evidence to form the spinel structure of these ferrites. Dielectric constant (ε′) and dielectric loss (ε") were observed to decrease with the increase of frequency due to hopping mechanism. Hysteresis curves exhibited soft nature of synthesized nanoferrites. Remanence (M R) and saturation magnetization (M S) were increased with the incorporation of Dy and Ni ions. The decreased in dielectric losses and increased in magnetic parameters suggested that these ferrites are potential candidates for magnetic recording heads. [ABSTRACT FROM AUTHOR]

• Copper doped cobalt sulphide nanoparticles were synthesized co-precipitation method. • Cubic structure of Cu doped Co 9 S 8 -NPs was observed at most prominent peak. • The red shift appeared in Cu doped Co 9 S 8 -NPs most suitable for photo-catalytic activity. • Electrical result shows that conductivity increases and resistivity decreases. • Thermoelectric measurements at unique critical temperature to rising current exponentially. Pure and copper doped cobalt sulphide (Co 9 S 8) nanoparticles were synthesized using aqueous chemical co-precipitation method. To study the effect of elemental composition Cu (0%, 1%, 5%, 10% &15%) on structural, optical, electrical and thermoelectric properties of Co 9 S 8 nanoparticles were investigated using various characterization techniques such as XRD, SEM, FTIR, UV–VIS and two probe methods. Cubic structure and grain size of pure and Cu doped Co 9 S 8 -NPs was confirmed by X-ray diffraction and SEM analysis. FTIR spectrum showed the different rotational and vibrational mode attached on the surface of the material. A redshift appeared in the band gap value (E g) as a function of the Cu dopant and high absorbance in the optical region makes the material suitable for photocatalytic activity. The electrical result show that conductivity increases and resistivity decreased as Cu content increases in Co 9 S 8 -NPs. Finally, thermoelectric measurements referred to the unique critical temperature for each sample where current starts rising exponentially. [ABSTRACT FROM AUTHOR]