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Cadmium substituted Z-type hexaferrites are prepared via the sol-gel route. The phase temperature of pre-sintered materials is studied from the thermal analysis. The single-phase of Z-type hexaferrite is found through X-ray diffraction investigation. The Crystallite sizes of the entire samples are evaluated within the range of 14–15 nm. The Fe–O stretching vibration band at 566 cm−1 is confirmed from Fourier transform infrared spectroscopy. Saturation magnetization (Ms) coercivity (Hc) and remanence (Mr) is examined by a vibrating sample magnetometer. The magnitude of Ms has been increased from 45.41 to 56.35 emu/g with an increase of Cd2+ concentration. The magnitude of Hc increased from 950.79 to 2186.95 Oe with an increment of Cd2+ concentration. Small values of squareness ratio (less than 0.5) showed the hard and single magnetic domain nature of the materials. The dielectric properties were analyzed using an impedance analyzer. Dielectric parameters show an increasing trend with the substitution of Cd2+. The maximum values of quality factor up to 17,000 and 10,000 are observed for sample Ba2·85Cd0·15Co2Fe24O41 at 1 GHz and 2.7 GHz, respectively. The high value of the Q-factor shows that these ferrites can be applicable for the formation of resonant circuits and multilayer chip inductors.

M-type Hexa-ferrites powders of chemical composition Ba0.5Sr0.1Zn0.4Fe12O19 was prepared by the use of the co-precipitation technique. The heat treatment of this ferrite composition was done at various temperatures (700, 800, 900, 1000, 1100, and 1200 °C) for 6 h. The X-ray diffraction (XRD) analysis of all the prepared powder samples confirmed the emergence of a hexagonal structure. The high-intensity peaks of the samples were indexed and showed a single phase. The size of crystallite was obtained within the range of 21–42 nm. The surface morphology was carried out with a Scanning electron microscope (SEM). The grain size showed the hexagonal shape, and average grain sizes were in the range of ~ 211 nm. Spectral information was found using the Fourier transform infrared (FTIR) spectroscopy to confirm the phase of M-type hexaferrite. The dielectric parameters were measured within the high-frequency range of 5 MHz - 3 GHz. The dielectric constant was increased with an increase in temperature. The dielectric studies were found by the establishment of space charge polarization as per the two-layer model provided by Maxwell-Wagner and the study of phenomena of Koop's theory. The magnetic characteristics including coercivity (HcB) and retentivity (Br) were measured from BH/JH hysteresis loops. The enhancement of coercivity was observed from 1.23 × 10+3 Oe to 1.50 × 10+3 Oe, while the retentivity increased from 1.334 × 10+3 G to 1.598 × 10+3 G with an increase in temperature. Outstanding properties of synthesized materials suggested their use in large-frequency applications, including recording media and permanent magnets.

Ho-substituted Li–Ni ferrites with composition L i1.2Ni0.4HoxFe2-xO4; 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.

In this study, an attempt has been made using different concentrations of rare-earth (RE) elements Yb, Gd in Ni–Zn spinel ferrite to examine the magneto-optical and electrical conductivity analysis of the prepared samples. RE doped Ni–Zn ferrite with composition Ni0.5Zn0.5YbxGdxFe2-xO4 (where, x = 0.00, 0.20, 0.40, 0. 60, 0.80 and 1.00) were prepared by one step sol-gel self-ignition approach. XRD and FESEM were used to examine the formation of a single-phase and variations in the grain size with the increasing contents of RE elements in Ni–Zn ferrite NPs. FTIR confirmed the vibrational studies of the RE doped spinel ferrite. The saturation magnetization, remanence, and coercivity elucidated the magnetic nature of the prepared samples. The decreasing trend was observed in the magnetization which may be due to the doping of RE elements at the B sites. UV–Vis spectroscopy verified the semiconducting nature of the synthesized samples which was because of the emergence of optical band gap in the semiconductor region (2.04 eV–2.28 eV). The temperature-dependent electrical conductivity ( σ DC ) was also studied to investigate the conduction mechanism over the 323 K–563 K temperature range. Yb and Gd doped NiZn ferrite is a good candidate for the nanoantennas, quantum information, sensing, isolators, modulators, data storage applications and energy storage devices because of their excellent magneto-optical and electrical properties.

In this research, we have fabricated cerium-doped nickel ferrite (NiCe0.04Fe1.96O4, C.NFO) and iron-doped cerium oxide (Ce0.96Fe0.04O2, F.CO) via a simple co-precipitation approach. The doped samples were supported with r-GO nanosheets via facile ultra-sonication methodology to develop ternary nanocomposite (C.NFO/F.CO/r-GO). The fabricated samples were characterized and their photodegradation and bactericidal aptitude were examined by using model organic chemicals (methylene blue (MB), SF-dyes, and Rhodamine-B (Rh–B)) and bacterial strains (Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus)), respectively. The results of the application studies revealed that fabricated C.NFO/F.CO/r-GO ternary nanocomposite exhibited excellent potential towards the photodegradation and bactericidal activities due to its photo-generated reactive species ( H O ⋅ , O ‾ 2 ⋅ & H 2 O 2 ). Distinctively, as-synthesized ternary nanocomposite, after 1.5 h of visible light irradiation, decomposed 99.12% MB-dye, 72.78% SF-dye, and 77.9% Rh–B dye. The reusability tests of C.NFO/F.CO/r-GO photocatalyst over MB dye revealed that it has excellent stability and can be reused four times with only ~5% loss in the photocatalytic efficiency. Furthermore, the fabricated ternary nanocomposite also showed outstanding bactericidal activity towards the gram-positive (S. aureus) and gram-negative bacterial strains (E. coli). In fact, like organic dyes, the main constituents of the bacterial cell wall are also organic molecules and are liable to decompose via redox reaction driven by photo-generated reactive species. Our fabricated ternary nanocomposite has an excellent aptitude to eliminate the toxic dyes and kill the bacteria present in the industrial effluents.

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.

The objective of this study was to synthesize, characterization and in vivo MRI experiment of cobalt ferrites as contrast agent. Iron oxide nanoparticles and cobalt ferrites were prepared by co-precipitation method. Iron oxides nanoparticles and cobalt ferrites were characterized by XRD, SEM, EDX, VSM and MRI. XRD analysis confirmed the spinel cubic structure of Fe3O4 with Miller indices (2 0 0), (2 2 0), (3 1 1), (4 0 0), (4 4 0) and average size of magnetic nanoparticles and cobalt ferrites were calculated about 11.13 nm, 12.21 nm and 16.85 nm using Scherer formula. XRD pattern confirmed that doping of Co increased the grain size of the magnetic nanoparticles. The morphology of iron oxide nanoparticles and cobalt ferrites were investigated by scanning electron microscope (SEM) and negligible agglomeration was found in ferrites. Spectra of EDX depicted the Fe, O and Cl elements in IONP. Magnetic properties were studied between Ms versus H using vibrating sampling magnetometer (VSM). Saturation magnetization (Ms) was enhanced with the doping concentration (20 %wt, 40 %wt) of Co with Fe3O4. MRI experiments were performed at low field MRI unit (0.35 Tesla, MAGNETOM) at open MRI diagnostic center Rawalpindi. T1-W, T2-W MRI images of liver and stomach of rabbits were taken using spin echo (SE) at TE = 15 ms and TR = 400 ms. IQ View software was used to estimate the intensity of signal induced by contrast agent pure iron oxides and cobalt ferrites (for liver, I = 1433 ± S.D = 111.5, spleen, I = 1009 ± S.D = 96.5), Co doped iron oxides nanoparticles (for liver, I = 1513 ± S.D = 102.2, spleen I = 1694 ± S.D = 219.2). This study concluded that cobalt ferrites induced high signal intensity of T2 contrast agents on liver and spleen as compared to iron oxides nanoparticles to diagnose many diseases in liver and spleen for clinical use of MR contrast agents.

Pr and Co co-doped BiFeO3 multiferroics of the following composition BiCoxPrxFe1-2xO3, where (x = 0.00, 0.05, 0.10, 0.15, 0.20 and 0.25) were prepared via sol-gel route. XRD, FTIR, SEM, VSM and VNA were used to evaluate the structural, phase, morphological and electromagnetic properties of Pr and Co co-doped multiferroics. All the undoped and Pr–Co co-doped multiferroics were of single rhombohedral phased whereas at higher concentration the orthorhombic structure was present. FTIR analysis exhibited the presence of orthorhombic phase. SEM images revealed that the grains of Pr and Co doped multiferroics are circular and elliptical in shape. Dielectric and electromagnetic properties were analysed using VNA from 1 to 6 GHz. Dielectric constant, dielectric loss factor, electric modulus, relative permeability, loss tangent, ac conductivity, and Q factor were determined from the toroidal shaped multiferroics. The double doping of Pr and Co multiferroics at x = 0.15 unveiled higher dielectric constant, ac conductivity and other related electromagnetic properties as compared to doped and undoped multiferroics. Pr and Co doped multiferroics also disclosed higher Q factor values at 2.65 GHz. Thin substrate as absorber and square shape resonator of Pr–Co co-doped BiFeO3 multiferroics at x = 0.15 were simulated using FDTD method. The first resonance absorption peak with a very high Q-factor was achieved at ~ 1.2 GHz whereas the second absorption peak was attained at ~ 2.4 GHz respectively. The absorptivity was also analysed corresponding to the different angles of incident for both TE- and TM-modes. Therefore, Pr–Co co-doped multiferroics have potential applications in the absorption and resonator devices in GHz regime.

In this research work, polymer coated magnetic nanoparticles were prepared by co-precipitation method. The samples were characterized by XRD, SEM, EDS, VSM and two probe DC conductivity measurements. XRD pattern indicated the existence of a sole cubic phase of Fe3O4 with Miller indices (2 2 0), (3 1 1), (5 1 1), (4 4 0). An average size of magnetic nanoparticles was about 22.9 nm and it was reduced to 21.3 nm and 19.4 nm after 1 wt. %. and 2 wt. % coating of PEG-6000, respectively. The morphology and size of the samples were investigated by scanning electron microscope (SEM). EDX spectra confirmed the coating of PEG on magnetic nanoparticles. Magnetic properties were examined by vibrating sample magnetometer (VSM). Saturation magnetization (M s ) decreased as the concentration of PEG increased in the magnetic material. Electrical properties of uncoated and polymer coated Fe3O4 nanoparticles were studied by two-probe conductivity meter. This study concluded that the thermal flow of charge in polymer coated magnetic nanoparticles can be evaluated at micro and nano level.

Indium (In) substituted copper ferrites with nominal composition CuInxFe2-xO4 (where 0.00 ≤ x ≤ 0.32) were prepared via sol gel route. Influence of In3+ on thermal, structural, spectral, magnetic and dielectric properties are elucidated. The complete decomposition and stable phase formation was assessed from thermal gravimetric analysis (TGA) and differential thermal gravimetric analysis (DTA). The structure of copper ferrite is single phase estimated from X-ray diffraction (XRD) analysis. Lattice constant (a) and crystallite size first increased then decreased with the inclusion of In3+ ions. Cell volume, X-ray density and bulk density are improved due to substitution of indium ions. Magnetic studies are carried out by vibrating sample magnetometer (VSM). The various magnetic parameters i.e saturation magnetization (Ms), coercivity (Hc) and retentivity (MR) are elucidated. The value of Ms and Hc are reduced with the substitution of In3+ ions. The squareness ratio, anisotropy constant and Bohr's magneton were also decreased as the inclusion of indium concentration. The value of dielectric constant (e′), dielectric loss (e") and tan loss were reduced as frequency increased. The surface morphology was studied by SEM (scanning electron microscopy). The small value of dielectric parameters and coercivity of synthesized ferrites suggested that indium substituted copper ferrites might be useful in switching and high frequency applications.

Bi–Cr-substituted Y-type hexa-ferrites were prepared via a micro-emulsion method. Formation of the hexagonal phase was confirmed by X-ray diffraction (XRD) analysis. The size of the crystallites of all the samples was in the range 31.58–37.67 nm and their Fourier transform infrared (FTIR) spectroscopy bands were observed in the range ~ 450–650 cm-1. These bands indicated successful incorporation of Bi–Cr in the Y-type hexagonal ferrites. The existence of metal-oxygen bands at the tetrahedral and octahedral sites confirmed that all the prepared samples exhibit Y-type hexagonal ferrites structures. The magnetic parameters such as saturation magnetization, retentivity and coercivity revealed significant variations with the increase of Bi–Cr contents. Frequency and composition dependent variations in the dielectric constant (e′), dielectric loss (e"), tan loss, and other parameters were observed, for example the value of e′ decreased as the Bi–Cr content increased. These optimised results are highly desirable for the application of these nanosized hard ferrites in various microwave devices

In this article, we have synthesized flake-like MoS2 nanoarchitecture by urea assisted hydrothermal method. To improve the electrical and electrochemical properties of MoS2 nanoarchitecture, we formed its nanocomposite (MoS2/r-GO) with 10% r-GO. After the addition of 10% r-GO, the nanocomposite shows the electrical conductivity of 1.24 × 10−1 Sm−1 that is higher than the pure MoS2 (2.2 × 10−7 Sm−1). The prepared nanocomposite also showed higher specific capacitance (441 Fg-1 at 1 Ag-1) than the pure MoS2 nanoarchitecture (248 Fg-1 at 1 Ag-1). Moreover, nanocomposite lost just 15.8% of its initial capacitance after 1000 charge-discharge cycles. The enhanced electrochemical activity of the nanocomposite is due to its unique flake-like structure and its reduced charge transfer resistance (Rct ~ 23.5 Ω). The 2-D flake-like structure of the electrode increased its contact area with the r-GO matrix and electrolyte. The higher electrical conductivity and specific surface area of the nanocomposite facilitated the faradaic and non-faradic charge storage mechanism. The r-GO matrix not only acted as a capacitive supplement but also facilitated the redox reaction because of its superior electrical conductivity. As the nanocomposite showed CV and CCD profiles in the negative potential window (−1 V to −0.53 V), therefore it has the potential to be used as a negative electrode material for hybrid supercapacitors applications. The observed results revealed the potential of the (MoS2/r-GO) nanocomposite-based cathode for hybrid supercapacitor applications.

Renewable energy resources play a valuable role in the global increase of energy demand. The research was performed to enhance the performance of plasmonic dye-sensitized solar cells (PDSSCs) by harvesting the maximum sunlight. In this context, the TiO2 nanoparticles for simple DSSCs and the Cu/rGO/TiO2 nanocomposites for PDSSCs were synthesized using the Sol–Gel and chemical reduction method. Authors demonstrated the utilization of synthesized Cu/rGO/TiO2 nanocomposite-based photoanode to fabricate the plasmonic dye-sensitized solar cells (PDSSCs). SEM, EDX, XRD, and UV/Vis techniques were employed to analyze the surface morphology, elemental composition, crystal structure, and absorbance spectra, respectively. Furthermore, IV measurements were performed on the fabricated devices, and it was observed that the Cu/rGO/TiO2 nanocomposite presented an enhanced efficiency of 5.14% in PDSSCs, which is more than that of the DSSCs-based on pure TiO2 nanoparticles. As an enhanced efficiency could be achieved by high optical absorption and electron injection rate, the PDSSCs with Cu/rGO/TiO2 nanocomposite have an enhanced efficiency due to the surface plasmonic resonance. An improved IPCE of 59.79% was also achieved in Cu/rGO/TiO2 nanocomposite-based photoanode, which might be due to the higher surface area of the photoanode.

Novel Zn0.90Co0.10O and Zn0.90Co0.05M0.05O (M = Ca, Ba, Cr, Pb) nanocrystals were synthesized by co-precipitation method and studied its structural, optical and electrical properties along with their photocatalytic activity. The XRD confirmed that Ca, Ba, Cr, and Pb have been incorporated without modifying ZnO hexagonal wurtzite structure. The microstructural parameters were calculated using Scherrer, W–H, and SSP methods. FTIR confirmed the existence of Zn–O vibrational modes. UV–vis spectra used to calculate the energy bandgap by using Tauc’s plot, Energy equation, Vegard’s law, and Derivative method. Optical parameters such as Urbach energy, refractive index, dielectric constant, extinction coefficient and optical conductivity were also studied. The IV measurements demonstrated that electrical conductivity was increased significantly by co-doping. The photocatalytic activity for the decolorization of methylene blue (MB) and methyl orange (MO) dyes under sunlight revealed the highest degradation efficiency for co-doped nanocrystals against MB as compared to MO in 100 min illumination. The grown nanocrystals are propitious sunlight driven photocatalyst to eradicate organic toxins.

In this work, nanocrystalline NiDyxFe2-xO4 ferrites (0.0 ≤ x ≤ 0.1) were synthesized via co-precipitation route. The impact of Dy+3 substitution on the various properties has been investigated. Structural, electrical, spectral and magnetic parameters were measured by XRD (X-ray diffraction), I–V (current-voltage), FTIR (Fourier transform infrared spectroscopy) and VSM (vibrating sample magnetometer) respectively. Morphological analysis was done by FE-SEM (Field emission scanning electron microscope). The formation of a single-phase FCC cubic spinel structure was confirmed by XRD patterns. With the help of XRD data, bond lengths and ionic radii were also calculated. FTIR spectra showed the formation of two typical frequency bands (υ1 and υ2) which represent metal-oxygen (M–O) vibrations at octahedral (B) and tetrahedral (A) sites. EDX spectrographs confirmed elemental composition. The M H curves demonstrated a decrease in saturation magnetization (Ms) and Bohr magneton (nB). The coercivity (Hc) showed a non –linear behaviour while anisotropy constant first increased and then decreased with Dy-substitution. NiDy0.025Fe1.975O4 showed maximum coercivity (102.06 Oe).

In this study, the sol-gel method was employed for the preparation of M-type hexaferrites Sr1-xAlxFe12-yCoyO19. Annealing of these samples was done at 1200 °C for 4 h. The single phase structure of all the prepared samples of M-type hexaferrites was observed by the X-ray diffraction (XRD) plots. The changes were examined in lattice parameters (a and c), cell volume, as well as in c/a ratio. The variations in c/a ratio were attributed to the changes in lattice parameters. The volume of the cell was found within the range 676.822–667.036 A3. Debye Scherrer's formula was used for the measurement of crystallite size, which was found in the range of 26.026 to 22.634 nm. The variations were also perceived in bulk density (δb) and porosity (%) with the incorporation of Al–Co concentration. There was reduction in X-ray density (δx), due to the increment in substitution concentration. Fourier transform infrared spectroscopy (FTIR) was performed in the range 400–3000 cm−1, which displayed specific absorption bands regarding hexagonal ferrites. Dielectric parameters including dielectric constant, dielectric loss, tan loss, and AC-conductivity revealed decreasing behavior, due to Al–Co substitution. The slope “n” was measured from graph of log(σac) as a function of log(ω), and found within the range 0.697–0.972. The grain boundary contribution of all the synthesized samples was evidenced via Cole-Cole plots, and extraordinary contribution of grain boundaries in conduction phenomenon was established by the presence of only one semi-circle in Cole-Cole plots. Therefore, the smaller dielectric parameters of the investigated M-type hexaferrites recommended their feasible role in large frequency applications (e.g., dielectric resonators, microwave absorbers, phase shifters, and stealth technology).

Structural, electronic, magnetic and optical properties of MFe2O4 (M = Mn, Co, Ni) ferrites are studied by first-principles approach. MFe2O4 ferrites exhibit stable structure in ferromagnetic phase. Density of states (DOS) and electronic band structures reveal that all ferrites show favorable spin polarization behavior in applications point-of-view. The CoFe2O4 ferrite shows half-metallic ferromagnetic characteristics with direct band gap, Eg = 0.713 eV in spin↑ state while NiFe2O4 shows spin gapless ferromagnetic behavior (with Eg = 0.0 at EF) in spin↑ state. The MnFe2O4 ferrite is found to have magnetically conducting behavior. MFe2O4 (M = Co, Ni) ferrites indicate 100% spin polarization at EF. The electronic band structures reveal electronic transition between O-2p to Fe-3d states in valence band (VB) or d-d transition between Fe-3d valence and conduction bands. The optical properties shows that the MFe2O4 (M = Mn, Co, Ni) ferrites exhibit transparent behavior to ultraviolet light indicating their suitability for use in optical filters and sensors.

Sr2Ni2TxFe28-xO46 (T = Cr3+, Bi3+, Al3+, In3+; x = 0.25) hexa-ferrites were fabricated via the sol-gel route. The phase temperature, which was obtained using thermo-gravimetric analysis (TGA), reveals that the X-type hexagonal phase of these materials is highly stable above 1200 °C. The phase formation was confirmed using X-ray diffraction (XRD) patterns. The variation in lattice strain shows the significant effect of substituted cations on the structure of the materials. The crystallite size of these materials was found in the range of 18–19 nm. The increase in dielectric constant, as well as with moderate loss, was observed in all substituted samples between 0.001 GHz and 1 GHz. The large values of dielectric constant were observed for Al3+ and In3+ substituted materials at higher frequency. The values of slope (n) reveal that all the materials exhibit frequency dependent ac conductivity. The Cole-Cole plots show the single semicircle for all samples. These semicircles of the Cole-Cole plots indicate that resistance inside the material is due to grains and grain boundaries. The both grain and grain boundaries resistance inside the material may cause large values of dielectric constant as well as the losses in the material. The large values of dielectric constant and impedance with moderate dielectric losses of these materials reflect their significant role in the fabrication of electronic devices as a radiation/microwave absorber or high frequency equipment components. Magnetic analysis shows the large values of magnetization and coercivity for Al3+ and In3+ substituted samples, which reflect that these materials might be beneficial for the absorption of electromagnetic radiation, formation of multilayer chip inductors and recording/storage purpose.

Cobalt (Co) doped MgZn spinel nanoferrites with composition Mg0.5Zn0.5Cox Fe2-xO4 at x = 0.0, 0.10, 0.20, 0.30, 0.40, 0.50 were prepared using sol-gel auto ignition method. The characterizations techniques such as FESEM, FTIR, XRD and VSM were used to determine the morphology, force constants, phase, structure and magnetic features of the samples. Lattice parameters, FWHM, d-spacing, crystallite size, micro strains and volume were investigated using high score plus software. Materials analysis using diffraction (MAUD) software was also used to study the Rietveld refinement properties of the Co doped MgZn ferrites. Physical properties such as porosity, X-ray and bulk density were also determined. Force constants of their respective absorption bands were calculated from FTIR of the Co doped MgZn nanoferrites. Single phase structure with cubic phase were observed for MgZn and Co doped MgZn at x = 0.0 whereas second phase was observed at higher Co concentrations respectively. FESEM show regular shape of the particles at low Co concentrations whereas agglomerations were observed at higher Co concentrations respectively. The magnetic properties of the Co doped MgZn ferrites were also investigated from VSM study. Magnetic remanence, coercivity, initial permeability, saturation magnetization, Bohr magneton and anisotropy constant were determined from VSM analysis. The coercivity, saturation magnetization, remanence, anisotropy constant and initial permeability were enhanced with the doping of ‘Co’ in MgZn nanoferrites. Response of the Co doped MgZn nanoferrites at high frequency regime was also evaluated. It can be seen that the response from all the Co doped MgZn nanoferrites was 2.84 GHz–5.96 GHz respectively and suggested the use of these nanoferrites for the operation of nanodevices in the X-band high frequency regime.

Silver nanoparticles (AgNPs) have received significant attention due to their distinctive antimicrobial, anticancer, catalytic and photochemical activity. The objective of this work is to amalgamate silver nanoparticles from the aqueous extract of Biamarckia nobilis seeds using green method, characterization using UV-visible spectroscopy, X-ray diffraction, transmission electron microscopy and FTIR spectroscopy. Further, its antimicrobial and anticancer activities were evaluated. The results displayed the characteristic UV peak, cubic phase with crystalline nature, spherical in shape having average size 14 nm, prominent peaks of bio-functional groups, good antimicrobial and anticancer activities.

In this work, we have modulated the structural, morphological, optical and thermoelectric properties of CZTS thin films (TFs) by controlling the concentration of tin atoms. The CZTS TFs were grown by simple chemical solution method by changing tin mole concentration from 0.5 mM to 2.0 mM (labeled as T1, T2, T3 and T4). XRD data have revealed the formation of best crystalline CZTS TF at 1.5 mM tin concentration because tin (Sn+4) atoms are placed its own lattice sites therefore achieved the best crystal quality of CZTS. Furthermore, the phase purity of CZTS TF was confirmed by Raman spectroscopy. The lattice vibration of CZTS TF were observed at 329 and 334 cm−1 with A1g mode and 367 cm−1 with B(TO) mode. The strongest Raman CZTS vibrational mode was observed for sample T3 which supported our XRD data. SEM images demonstrated that the surface of grown CZTS thin films became smoother with increasing the mole concentration of tin atoms up to 1.5 mM because the density of CuS grains has minimum value for this sample. The optimum band gap of T1, T2, T3 and T4 samples was estimated to 2.23, 2.15, 1.91 and 1.82 eV respectively which also confirmed that sample T3 has band gap value very close to reported value. The Seebeck coefficient, electrical conductivity and power factor values were enhanced from (243–762 μV/°C), (21–152 S/cm) and (1.24 × 10−4- 8.82 × 10−2Wm−1K−2) with increasing the mole concentration of tin (0.5–1.5 mM) at measurement temperature 100 °C.

Co2+ and Mn2+ co-doped lithium spinel ferrites with the chemical composition Li0.5Fe2.5-0.5xCoxMnxO4 (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 A and then decreased up to 8.367 A, 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 Li0.5Fe2.5O4 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 (eʹ), complex dielectric constant (eʹʹ) and tangent loss (tanδ) were analyzed between 1 MHz and 3 GHz. By increasing the frequency, eʹ, eʹʹ, 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.

High quality magnetically separable Ni0.65Zn0.35Fe2O4 nanoparticles were synthesized by surfactant assisted co-precipitation method. Spinel structure of these ferrite nanoparticles was confirmed by X-ray diffraction (XRD). Reduced graphene oxide (rGO) was prepared by wet chemical approach and then utilized to make the composites with ferrite nanoparticles. The successful homogenous distribution of ferrites nanoparticles onto the graphene sheets was observed by scanning electron microscopic (SEM) analysis. The ferrite@rGO composite exhibited the strong absorption in visible region as observed by UV–vis measurements. Optical band gap studies confirmed that the prepared spinel ferrite Ni0.65Zn0.35Fe2O4 nanoparticles can be utilized for visible light driven photocatalytic activity studies. The optical (direct) band gap for Ni0.65Zn0.35Fe2O4 nanoparticles as calculated by Tauc plot was found 1.91 eV. This bandgap lies in the visible region i.e.

Seismic reservoir characterization is a renowned technique to obtain a better understandingand quantification of hydrocarbon bearing reservoirs by integration of seismic attributes, post stack inversion and wireline log analysis. In current case study, a methodology based on these techniques is proposed, and its applicability is tested for delineating the secondary reservoir potential of the Eocene carbonates (Habib Rahi and Sui Upper Limestone) in Qadirpur area, Lower Indus Basin, Pakistan. The application of post stack inversion provides a reasonable estimate of the acoustic impedance and enables the spatial distribution of important petrophysical properties (effective porosity and water saturation) available at sparse well locations. This distribution is facilitated by developing geostatistical relations between seismic and well derived reservoir properties in the range of seismic resolution. The results from all integrated techniques depict fluid saturated zones at Habib Rahi (gas at 907–922 m; water at 953–973 m) and Sui Upper Limestone (gas at 1192–1208 m) levels. The spatial distribution of the reservoir properties (effective porosity and water saturation) obtained via seismic data shows a very good calibration at the location of wells and reflects significant secondary reservoir potential for Eocene carbonates in the study area (effective porosity in the range of 7–26% and water saturation in the range of 35–60%). Furthermore, the methodology tested over here will be advantageous for the characterization of oil/gas reservoirs in various basins of Asia and other parts of world with similar geological settings.

New yttrium substituted manganese ferrite (MnYxFe2-xO4) nanoparticles (NPs) were prepared by low cost reverse micelle micro-emulsion method by utilizing cheap raw materials like Paraffin, Triton X-100, and 1-butanol and corresponding metal salts. The Y3+content (x) range was kept 0 ≤ x ≤ 0.16. Thermogravimetric analysis (TGA) of un-annealed precipitates was carried out to probe the phase formation temperature. The annealing of precipitates of all compositions of MnYxFe2-xO4 nanoparticles was carried at 400 °C for 4 h (h). The annealing was carried out under vacuum to control the oxidation of manganese. The effect of Y3+ cations on structural, spectral and dielectric properties was investigated by X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy and impedance analyzer measurements at room temperature. XRD patterns confirmed the formation of MnFe2O4 and its derivatives with yttrium. Site radii and bond lengths were calculated from XRD data. FTIR spectra confirmed the tetrahedral (A) and octahedral (B) sites in all compositions of MnYxFe2-xO4 nanoparticles, which is characteristic of spinel ferrites having FCC (face centered cubic) structure. Scanning electron microscopic (SEM) analysis confirmed the spherical morphology of ferrite particles. Dielectric parameters analysis in the frequency range from 1 × 106 Hz to 3 × 109 Hz suggested that these ferrite particles may find their potential applications in high frequency devices fabrication.

Magnetic nanomaterials have been extensively studied due to their numerous applications in almost all types of electronics as well as in biomedical fields. In this work, Ni0.65Zn0.35NdxFe2-xO4 nanoparticles (0.00 ≤ x ≥ 0.075) have been prepared by co-precipitation method. The structural and electromagnetic properties were tuned by doping of rare earth. The prepared nano-ferrites were annealed in furnace for 5 h at 800 °C. The structural, spectral, magnetic and electrical behavior of Ni0.65Zn0.35NdxFe2-xO4 nanoparticles was investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometery (VSM) and current voltage measurement (I-V) measurements. The objective of this work is to study the variation of magnetic and electric properties as a function of concentration of dopant i.e. rare earth Nd3+ cations. Formation of single phase in all prepared sample except x = 0.075 was confirmed by XRD analysis and estimated crystallite size was 14–26 nm. The lattice parameter, electric properties and magnetic parameters showed non-linear behavior with the doping of Nd+3. Intrinsic metal ion vibrations of spinel ferrites were explained by FTIR spectra recorded in the range of 400–2000 nm. Influence of Nd+3 contents on structural, magnetic, and electrical parameters has been discussed in detail.

Copper (Cu) substituted Co Ce nanoferrites with nominal composition of Co1-xCux Ce0.05Fe1.95O4 (x = 0.00, 0.25, 0.50, 0.75, 1.00) were prepared by sol-gel route. The sintering of the Cu doped Co Ce nanoferrites was done at 700 °C to investigate the desired properties of the Cu doped Co Ce nanoferrites. The combination of transition metal (Cu) and rare earth (Ce) were employed to tailor the characteristics of the spinel ferrites. The constant ratio of rare earth and systematic doping of Cu in Co ferrite was incorporated to see the effects of these ions in spinel ferrite. FTIR, FESEM, XRD and VSM were used to study the vibrational bands, phase, morphology, structure and magnetic properties of the Cu doped Co Ce spinel nanocrystalline ferrites respectively. Average crystallite size, volume, strain and lattice parameters were evaluated from XRD. Bulk, X-ray density, and porosity were increased with Cu doping in Co Ce spinel ferrites. Rietveld refinement of the Cu doped Co Ce nanoferrites was done using MAUD software. Site radii, shared and unshared edges, bond lengths due to the Cu substitution were also study by Bertaut technique. FTIR studies were done to find out the force constants and absorption bands at tetrahedral and octahedral sites. Magnetic loops were recorded from VSM and magnetic properties such as remanent magnetization, coercivity, saturation, magnetic anisotropy constant (K), initial permeability and Bohr magnetic moments were determined. Saturation, remanence, coercivity, Bohr magnetic moment and anisotropy constant of the Cu doped Co Ce nanoferrites were decreased. However, Yafet-Kittel (Y K) angles were found to be enhanced with Cu doped Co Ce nanoferrites. High frequency response of the Cu doped spinel nanoferrites in microwave region was also evaluated using the saturation data of the samples. All the Cu doped Co Ce nanoferrites samples are suggested to be used in microwave for X-band regime.

The structural, mechanical, electronic and magnetic properties of quaternary YFeCrX (X = Al, Ga, In, Si, Ge, Sn, P, As, Sb) Heusler alloys are reported. The structural stability, electronic and magnetic properties of Heusler alloys are studied by implementing spin polarized density functional theory (DFT). All alloys with cubic structure are found stable in ferromagnetic phase. Among the YFeCrX alloys, the YFeCrGa, YFeCrSi and YFeCrSb alloys exhibit high values of bulk moduli. The calculated cubic elastic constants show that all alloys fulfill the mechanical stability criteria. The band structures (BSs) and density of states (DOS) shows half metallic (HM) behavior of alloys. Among the alloys, the YFeCrSi, YFeCrGe, YFeCrSn, YFeCrP and YFeCrSb alloys exhibit indirect band gap in S↓ channel and show 100% spin-polarization. The YFeCrX (X = Si, Ge, Sn, As, Sb) alloys obey the Slater - Pauling rule, μ T o t a l = Z T o t a l - 18 while the YFeCrP alloy found to follow the Slater-Pauling rule, μ T o t a l = 24 - Z T o t a l . Thus, the alloys which have high magnetic moment are expected to have high Curie temperature T C suitable for applications in spintronic devices.

Nickel ferrites with high theoretical capacitance value as compared to the other metal oxides have been applied as electrode material for energy storage devices i.e. batteries and supercapacitors. High tendency towards aggregation and less specific surface area make the metal oxides poor candidate for electrochemical applications. Therefore, the improvements in the electrochemical properties of nickel ferrites (NiFe2O4) are required. Here, we report the synthesis of graphene nano-sheets decorated with spherical copper substituted nickel ferrite nanoparticles for supercapacitors electrode fabrication. The copper substituted and unsubstituted NiFe2O4 nanoparticles were prepared via wet chemical co-precipitation route. Reduced graphene oxide (rGO) was prepared via well-known Hummer's method. After structural characterization of both ferrite (Ni1-xCuxFe2O4) nanoparticles and rGO, the ferrite particles were decorated onto the graphene sheets to obtain Ni1-xCuxFe2O4@rGO nanocomposites. The confirmation of preparation of these nanocomposites was confirmed by scanning electron microscopy (SEM). The electrochemical measurements of nanoparticles and their nanocomposites (Ni0.9Cu0.1Fe2O4@rGO) confirmed that the nanocomposites due to highly conductive nature and relatively high surface area showed better capacitive behavior as compared to bare nanoparticles. This enhanced electrochemical energy storage properties of nanocomposites were attributed to the graphene and also supported by electrical (I-V) measurements. The cyclic stability experiments results showed ~65% capacitance retention after 1000 cycles. However this retention was enhanced from 65% to 75% for the copper substituted nanoparticles (Ni0.9Cu0.1Fe2O4) and 65–85% for graphene based composites. All this data suggest that these nanoparticles and their composites can be utilized for supercapacitors electrodes fabrication.

LiNiCo spinel ferrites were prepared, by doping with rare earth metals Nd and Pr, according to micro-emulsion method. In order to study the effect of Nd and Pr, the crystal structure and magnetic properties of prepared ferrites were scrutinized in detail. The endorsement of single-phase spinel ferrites with the co-occurrence of orthophase was confirmed by XRD and FTIR. The average crystallite size varied with increasing the doped concentration of Nd and Pr, which is in the range from 28 nm to 70 nm. Magnetic properties were analyzed by VSM within range of −10,000 Oe and 10,000 Oe. MS and MR values decreased with the increase in concentration. The value of HC, MR, and MS showed stability for transformer core where electromagnetic interference is reduced. Hence synthesized ferrites LiNi0.35−yCo0.15PryNdxFe2−xO4 are suitable for transformers and induction. Keywords: Li-Pr, Praseodymium, Neodymium, Nanocrystalline ferrites, XRD, Microemulsion, Magnetic properties

In this study Co-Ni co-doped nanocrystalline manganese ferrites were fabricated via co-precipitation method. The annealing of as prepared nanoferrites was done at 950 °C for 7 h. The powder X-ray diffraction (XRD) confirmed that all samples possessed cubic spinel structure. The crystallite size was determined by Scherrer’s equation that lies in the range of 27–35 nm. The spectral analysis confirmed bending and stretching of bonds at octahedral (B) and tetrahedral (A) sites. The spectral bands were shifted towards the longer wavelength side and these indicate the incorporation of dopants cations (Co-Ni). The magnetic parameters were measured from the M-H loops of nanoferrites. With the increase of Co-Ni contents, the saturation magnetization (Ms) increased up to x = 0.15 and then it decreased. The dielectric properties of all compositions were studied in 1 MHz–3 GHz range and were discussed in the light of Debye-type reduction phenomenon by following the Koop’s theory. The dielectric and magnetic behavior evaluation suggested that synthesized ferrites are suitable for microwave devices fabrication.

Background: Spinel ferrites have great scientific and technological significance because of their easy manufacturing, low cost and outstanding electrical and magnetic properties. Nickel ferrite nanoparticles are ferromagnetic material with an inverse spinel structure. They show remarkable magnetic properties and hence have a wide range of applications in magnetic storage devices, microwave devices, gas sensors, telecommunication, drug delivery, catalysis and magnetic resonance imaging. Objective: The aim and objective of this research article is to study the relative effect of NiErxFe2-xO4 nanoparticles and their composites with reduced graphene oxide (rGO) for the photocatalytic degradation reaction and other physical parameters. Method: Rare earth Er3+ substituted NiErxFe2-xO4 nanoparticles were synthesized via the facile wet chemical route. Six different compositions of NiErxFe2-xO4 with varied Er3+ contents such as (x) = 0.00, 0.005, 0.01, 0.015, 0.02 and 0.025 were selected for evaluation of the effect of Er3+ on various parameters of NiFe2O4 nanoparticles. Reduced graphene oxide (rGO) was prepared by Hummer’s method and was characterized by UV-Visible spectroscopy, X-ray powder diffraction and Raman spectroscopy. Nano-heterostructures of NiErxFe2-xO4 with rGO were prepared by the ultra-sonication method. Results: X-ray powder diffraction (XRD) confirmed the spinel cubic structure of all the compositions of NiErx- Fe2-xO4 nanoparticles. The photocatalytic degradation rate of methylene blue and congo red under visible light irradiation was found faster in the presence of NiErxFe2-xO4-rGO nanocomposites as compared to bare nanoparticles. It was also investigated that as the Er3+ contents were increased in NiErxFe2-xO4 nanoparticles, the dielectric parameters were largely affected. The room temperature DC-resistivity measurements showed that the Er3+ contents in NiFe2O4 are responsible for the increased electrical resistivity of ferrite particles. The electrochemical impedance spectroscopic (EIS) analysis of NiErxFe2-xO4 nanoparticles and NiErxFe2-xO4-rGO nanocomposites revealed that the ferrite particles possess low conductance as compared to the corresponding composites with graphene. Conclusion: The data obtained from all these characterization techniques suggested the potential applications of the NiErxFe2-xO4 nanoparticles and NiErxFe2-xO4-rGO nanocomposites for visible light driven photo-catalysis and high-frequency devices fabrication.

This paper reports results on the structural stability, mechanical, electronic and magnetic behaviour of quaternary ScNiCrX (X = Al, Ga) Heusler alloys under pressure. First principles approach is applied to calculate the structural, mechanical, electronic and magnetic properties of ScNiCrX alloys under pressure. In ferromagnetic phase, both alloys (in Type-γ configuration) are stable. Over a wide pressure range, the calculations of cubic elastic constants (Cij) for both alloys fulfill the necessary criteria for structural stability. Under pressure up to 6.0 GPa, the ScNiCrAl alloy shows half-metallic ferromagnetic behaviour. The ScNiCrGa alloy exhibits half-metallic behaviour over a wide range of pressure (up to 16.0 GPa) as compared to ScNiCrAl alloy. For ScNiCrAl alloy, the spin ↓ energy band gap (Eg) increases (0.27–0.43 eV) with increase in pressure (0.0–6.0 GPa) while for ScNiCrGa alloy Eg increases from 0.30 to 0.58 eV with increase in pressure from 0.0 to 16.0 GPa. For pressure up to 10.0 GPa, the calculated total magnetic moment, MT (for both alloys) exhibit Slater-Pauling rule, MT = (NV – 18) μB. Up to 6.0 GPa, it is expected for ScNiCrAl alloy to show 100% spin-polarization (at Fermi-level, EF) while for ScNiCrGa alloy, 100% spin-polarization is possible to achieve for pressure up to 16.0 GPa. On the basis of results, it is suggested that the ScNiCrX Heusler alloys could be suitable candidates for spintronic devices to operate under harsh environment.

BiFe1-xNixCoxO3 multiferroics (x = 0.00, 0.05, 0.1, 0.15 and 0.2) were fabricated by micro-emulsion process. Differential scanning calorimeter (DSC) plot exhibited broad exothermic peaks at 264.33 °C and 320.8 °C. X-ray diffraction (XRD) patterns indicated the rhombohedral phase with the R3c phase group. The crystallite size ranges from 48 to 11 nm. Bulk and X-ray densities were optimized by increasing cobalt and nickel concentration. Magnetic parameters such as retentivity (Mr), saturation magnetization (Ms) and coercivity (Hc) were studied for different compositions of BiFe1-xNixCoxO3. BiFe0.6Ni0.4Co0.4O3 behaves as ferromagnetic material having maximum saturation magnetization (10.6 emu/g) and maximum Mr (5.2 emu/g). Enhanced magnetic properties were attributed to the difference in magnetic moment of doping element and Fe3+ ions. Dielectric parameters had great influence of doping (Ni Co) in high frequency region. It was observed that by increasing doping level dielectric parameters were decreased appreciably.

Objective: This study was carried out to demonstrate the effect of sprouting on the major flavonols and quercetin glycosides in onion powders developed from four onion cultivars (Punjab White, Punjab Naroya, PRO-6 and Commercial) of Indian Origin. Methods: The major flavonols summing up total flavonoids and quercetin glucosides comprising up to the total quercetin glucoside concentration were determined by High performance liquid chromatography and Fourier transform infrared (FTIR) spectroscopy. Results and conclusions: The major flavonols were quercetin, myricetin and kaempferol, which were found to be significantly higher (p

A graph labeling is an algorithm that assignment the labels, traditionally represented by integers, to the edges or vertices, or both, of a network(graph) G. Formally, given a graph $$G = (V, E)$$ , a vertex labeling is a function of V to a set of labels. A graph with such a function defined is called a vertex-labeled graph. Likewise, an edge labeling is a function of E to a set of labels. In this case, the graph is called an edge-labeled graph. We study an edge irregular reflexive k-labeling for the Cartesian product of two paths, two cycles and determine the exact value of the reflexive edge strength for the Cartesian product of two paths and two cycles.

Advancing smart production systems for green production remains a crucial priority for manufacturers, while the vision to achieve green supply chain management process (GSCMP) remains obstructed due to using less fuel-efficient technologies. This study suggested an intelligent logistics design that infused technological indicators with logistics performance indices (LPIs) to minimize carbon damages in a panel of 102 countries. The study used patent applications and trademark applications to analyze the technological progress, whereas LPIs&mdash, i.e., LPI-1 for assessing quality and competence services, and LPI-2 for trade and transport infrastructure&mdash, are used to determine supply chain management process across countries. The results show that carbon damages follow a U-shaped structure with technology-induced LPIs (TI-LPIs) and GDP per capita. The country&rsquo, s GDP per capita and TI-LPIs decrease carbon damages up to US$15,000,000, while the moderation of patents application (and trademark applications) with LPI1 and LPI2 substantially decreases carbon damages up to US$13,800,000 (US$34,100,000) and US$6,100,000 (US$20,200,000), respectively. The causality estimates confirmed the growth-led carbon damages, technology-led carbon damages, growth-led logistics indices, and technology-led growth across countries. The results emphasized the need to move forward by adopting fuel-efficient technologies to minimize carbon damages across countries.

A systematic investigation on structural, electronic, elastic, mechanical and optical properties of novel 1:1 stoichiometric rare-earth $$\mathrm{HoX}\ (\mathrm{X}=\text {Pd, Ag and Cd})$$ intermetallic compounds has been made via ab-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 $$\mathrm{HoX}\ (\mathrm{X}=\mathrm{Pd, Ag and Cd})$$ compounds. The determined crystal structure stability, compressibility and fracture strength of compounds are enhanced with X in the order $$\mathrm{HoPd}>\mathrm{HoAg}>\mathrm{HoCd}$$ . 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 $$(\hbox {Pd}\rightarrow \hbox {Ag}\rightarrow \hbox {Cd})$$ . The mechanical constants i.e., bulk modulus (B), Young’s modulus (E), shear modulus ( $${G}_{\mathrm{H}}$$ ), Pugh’s ratio $$(B/G_{\mathrm{H}})$$ , 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 $$(\textit{Q}^{*}$$ ) 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 $$\mathrm{HoX}\ (\mathrm{X}=\text {Pd, Ag and Cd})$$ compounds. The bond order calculations demonstrate the highest strength of HoCd compound among the herein studied compounds.

We propose and compare algorithms to allocate upstream PON capacity, where multiple virtual operators generate independent frame-level allocation over shared infrastructure. Our fragmentation-based approach shows the ability to limit latency increase to a few microseconds.

Communicable and noncommunicable diseases cause millions of deaths every year, increased billions of healthcare expenditures, and consequently increase trillions of economic losses at a global scale. This study more focused on the prevalence of communicable diseases, including COVID-19 that is an emerging pandemic, which affects the global economy. The objective of the study is to examine the impact of population density, lack of sanitation facilities, chemical concentration, fossil fuel combustions, poverty incidence, and healthcare expenditures on communicable diseases including COVID-19. The study covered a large panel of heterogenous countries to assess the relationships between the stated factors by using the robust least square regression, Granger causality test, and innovation accounting matrix. The study used a time series data from 2010 to 2019 for assessing the determinants of communicable diseases, while it is further extended with the current data of 2019-2020 for the COVID-19 pandemic. The results of the study show that high population density, lack of primary handwashing facilities, chemicals used in manufacturing value-added fossil fuel combustion, and poverty headcount substantially increase communicable diseases. In contrast, population diffusion, low carbon concentration in air, renewable fuels, and healthcare expenditures decrease infectious diseases in a panel of 78 countries. The causal inferences found the bidirectional relationship between communicable diseases and primary handwashing facility, and carbon emissions and poverty headcount, whereas the unidirectional relationship is running from lack of sanitation to infectious diseases, economic growth to carbon emissions, and communicable diseases to fossil fuel combustion across countries. Communicable diseases increase healthcare expenditures and decrease the country’s economic growth which is a vital concern of the global economy to confront the outbreak of novel coronavirus through increasing the healthcare budget in national bills and stabilize financial activities at a worldwide scale.

A series of BiFe1-xHf(3/4)xO3 ( 0%, 5%, 10%, 15% and 20%) nanoparticles were synthesized by simple auto combustion technique using citric acid as a fuel. Thermogravimetric (TGA), differential thermogravimetric (DTA), structural, magnetic, dielectric and ferroelectric analyses were investigated. Thermogravimetric analysis provides information of temperature at which phase develops (600 °C). DTA predicts ferroelectric to paraelectric transformation temperature which is found to be 822 °C. X-ray diffraction (XRD) results confirm formation of distorted rhombohedral structure for all compositions along with few traces of Bi25FeO40. The tolerance factor is increased from 0.845 to 0.853 due to larger ionic radius of Hf4+ substitution on Fe site. Crystallite size (D) is found in the range of 24.2–30.48 nm. Saturation magnetization (Ms) is increased to 16 times and remanent magnetization (Mr) is increased to 8 times than that of pure BiFeO3. This increment in magnetic parameters is due to reduction of oxygen vacancies, small crystalline size (less than 62 nm), structural distortion and unbalancing condition for antiferromagnetic magnetic moments of Fe3+ ions. Dielectric parameters depict decrement behavior with increasing of applied field up to 3 GHz. For Fe1-xHf(3/4)xO3, lower value of dielectric permittivity for all compositions is due to reduction of polarization and less growth of grains but more growth of grain boundaries because of mismatching of Hf and Fe3+ ions. P-E hysteresis loop changes from round shape to elliptical shape and it confirms less lossy nature of ferroelectric loops. Higher values of Ms as well as Mr but lower values of dielectric constant as well as remanent polarization for these nanoparticles make them useful for MeRAM (magnetoelectric random access memory) and high resonant applications.

Spinel and garnet nanostructured ferrites have been used for various potential applications. Single phase spinel and garnet nanoferrites have been used for different applications in many fields. Ni-Zn (Ni0.5Zn0.3Al0.2Fe2O4) ferrite with spinel structure and YAIG (Y2.8Al0.2Fe5O12) ferrite with garnet structure were synthesized using sol-gel technique. The structural, morphological and magnetic studies were done for spinel and garnet nanoferrites. X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were used to investigate the structural, morphological and magnetic properties of the spinel and garnet nanoferrites respectively. Single phase spinel and garnet nanocrystalline ferrites were confirmed from XRD analysis. Circular and cubic shape morphology was observed for spinel and garnet nanoferrites respectively. Static magnetic characteristics of the Al doped spinel and garnet nanoferrites (saturation, remanence, coercivity and magnetic squareness) were measured from the hysteresis loops. Dynamic magnetic properties such as initial permeability, Q factor and magnetic losses of the Al doped spinel and garnet nanoferrites were also evaluated from magnetic measurements. Spinel and garnet nanoferrites prepared at low temperature may have potential in industrial and technological applications e.g. transformers, switching, cores, filters, sea bed logging, MLCI's, microwave absorption bio medical applications and microwave frequency (C and X) band applications.

Dysprosium (Dy) doped Y-type strontium hexa ferrites of the following composition Ni2Sr2DyxFe12-xO22 where (x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25) were prepared through co-precipitation process. Phase analysis of the investigated samples was carried out by characterizing through (XRD) X-ray diffraction which confirmed the pure phase of Y-type hexaferrites. Dysprosium ion doping influenced lattice parameters i.e. lattice constants (a, c), crystallite size, (c/a) ratio, cell volume and porosity. The calculated crystallite size was in the range of 88–159 nm. FTIR plots showed that the characteristics bonds of Ni2Sr2DyxFe12-xO22 are appreciably influenced by the incorporation of Dy contents. The results of dielectric parameters revealed that dielectric constant, dielectric loss, tanloss were decreased with an increase in frequency. At 6.0 × 108 Hz, dielectric constant decreased from 5.55 to 3.69 with increasing Dy concentration. Owing to Maxwell-wagner type relaxation, the decrease in dielectric constant was noticed at higher frequency. The smaller dielectric constants and dielectric losses make these materials suitable for their applications in microwave devices fabrication.

Impact of gallium (Ga) on structural, morphological and magnetic properties of yttrium iron garnet (YIG) nano-sized ferrites with nominal composition (Y3GaxFe5-xO12, where x = 0.00, 0.40, 0.80, 1.20, 1.60) has been investigated. The samples were prepared via sol-gel auto combustion route. XRD (X-ray diffraction), FESEM (field emission scanning electron microscopy) and VSM (vibrating sample magnetometer) were used to unfold the structural, morphological and magnetic properties of Ga substituted YIG ferrites. Single phase structure of all samples was confirmed through XRD. Cations distribution such as site radii, hopping bond length, shared and unshared edges of the Ga substituted YIG ferrites were also determined. Physical properties such as X-ray density (Dxrd), bulk density (Dbulk), porosity and lattice parameters were found to increase with increasing Ga concentration. FESEM images represented well crystallized and homogenous grains for YIG whereas porous structures were found for Ga substituted ferrites. The grain size of these samples was found in the nano regime (40–86 nm). Magnetic properties such as magnetic saturation, coercivity, remanence, initial permeability, Bohr magneton and anisotropy constant (K) were calculated from hysteresis loops. However, Yafet and Kittle (Y-K) angles were also calculated. Y-K angles were increased with Ga concentration in YIG nano-sized ferrites. Low coercivity and moderate magnetization suggested the use of these ferrites for electromagnetic microwave absorption and frequency agile antenna for wireless communication. Furthermore, the range of operated frequency in microwave region of these nanoferrites suggests the use of these ferrites for high frequency (S and C bands) applications.

In this work erbium (Er3+) substituted cobalt zinc ferrite having general formula Co0.70Zn0.30ErxFe2-xO4 (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05) were fabricated using micro-emulsion technique. The substitution of Er was done for the purpose of tuning the optical band gap. Er+3 substituted nanoparticles were annealed at 700 °C for 7 h. A typical composition of Co0.70Zn0.30ErxFe2-xO4 was utilized to make the nanocomposites material with reduced graphene oxide (rGO), that was prepared by facile chemical route. The main purpose of graphene was to enhance the conductivity of ferrite particles. All these ferrite particles and a composite were characterized by X-rays diffraction (XRD), UV–Visible spectroscopy and SEM for structural elucidation and morphology studies. Single phase spinel structure was confirmed by XRD analysis and crystallized size calculated by Scherer formula was found in the range 35–60 nm. SEM confirmed the well dispersed ferrite particles among graphene sheets. All the Er-substituted ferrite particles were subjected to dielectric parameters study. One typical composition of Co0.70Zn0.30ErxFe2-xO4 particles and its composites with rGO were utilized for photocatalysis study using methylene blue as model organic compound in the presence of visible light. Current-voltage (I-V) measurements of ferrites nanoparticles and their composites with graphene were also studied. The results of all these techniques were agreed with each other and suggested the various potential applications of these nanoparticles.

Effect of Mg-Sr substitution on thermal, structural, spectral, dielectric and magnetic properties were explored in the X-type hexagonal ferrites having composition of Ba2-xMgxCo2-ySry Fe28O46 (x = y = 0, 0.1, 0.2, 0.3, 0.4, 0.5) synthesized via a sol-gel auto-combustion process. The sintered material was characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), dielectric measurement and vibrating sample magnetometer (VSM) techniques. The sintering temperature necessary for the entire degradation of nitrates and the hexagonal phase development was found 1250 °C which was determined from thermo-gravimetric analysis. The formation of the single phase hexagonal was confirmed from XRD patterns. The lattice constants and cell volume were found to be decreased. This decreased was attributed to the lower ionic size of the substituted metal ions. The porosity of the synthesized material was found to be decreased from 0.463 to 0.417 with the increase in the substitution. FTIR spectroscopy of Mg-Sr doped material revealed the characteristics absorption bands of hexa-ferrites and it was investigated in the frequency range of 400–1000 cm−1. The dielectric measurement has been explored as the function of frequency and composition. Ac conductivity was found to be increased from 1.46 to 2.029 Ω cm−1. The Cole-Cole graphs of prepared materials revealed the promising role of grain boundaries in the conduction mechanism. The improvement in the coercivity was observed with the increase in the Mg-Sr cations, while the saturation magnetization was decreased with the increase in the substitution. The higher value of the coercivity of these synthesized material proposed their use in longitudinal recording media.

Rare earth doped bismuth (Bi) iron garnets (BIG) having composition Bi3−xRxFe5O12 for x = 1.5 (here R stands for rare earth elements like Y, Gd, Pr, Ho and Yb) have been studied in this work. The samples were prepared using sol-gel method. X-Ray diffraction (XRD), Scanning electron microscope (SEM), Fourier transform infrared spectroscope (FTIR), Vibrating sample magnetometer (VSM) and Vector network analyzer (VNA) were employed on the samples to evaluate the properties of the doped Bi nanogarnets. Single-phase garnet structure was confirmed through XRD and the crystallite sizes were found to be 66–73 nm, depending upon the type of rare earth ions. SEM images helped to observe the morphology and measurement of grain size of the doped Bi nanogarnets. Vibrational bands showed the presence of garnet phase and were confirmed through FTIR analysis. Detailed dynamic magnetic and dielectric properties were measured using VNA from 1 to 6 GHz. Real and imaginary part of the permittivity, permeability, dielectric and magnetic losses, ac conductivity, electric modulus and Q factor were calculated for the rare earth doped Bi nanoferrites. Gd doped Bi nanoferrites showed higher permittivity values whereas Pr doped show higher ac conductivity as compared to other samples. Yb doped Bi nanoferrites have Q factor values at 4.8 GHz. Static magnetic properties of the doped Bi nanogarnets were investigated using magnetic loops. Magnetic remanence (Mr) Saturation magnetization (Ms) and coercivity (Hc), Bohr magneton, anisotropy constant and initial permeability were also calculated. The dielectric and magnetic studies of the rare earth doped Bi nanogarnets suggested the applications of these rare earths doped nanogarnets for microwave devices and high frequency applications in GHz regime. Keywords: Bismuth nanogarnets, Rare earth substitution, X-ray diffraction, High frequency measurements, M-H loops

Rare earth Ce doped NiZn with composition of Ni0.8Zn0.2CexFe2−xO4 at x = 0.00, 0.02, 0.04, 0.06, 0.08 and 0.10 were synthesized via sol-gel route. Rare earth Ce was doped to tune the structural and magnetic properties of the spinel ferrites. Therefore, the systematic effect of Ce on the structural, morphological and magnetic studies was carried out. FTIR, XRD, FESEM and VSM were carried out to investigate the metal stretching vibrations, structure, phase, morphology and magnetic characteristics of Ni0.8Zn0.2CexFe2−xO4 nanoferrites respectively. The size of the crystallites, cell volume and lattice parameters (theoretical and experimental) were decreased with Ce3+ doping. The size of the crystallites was in the range of 41–9 nm. The physical characteristics such as X-ray density, bulk density and porosity were also decreased with Ce3+ substitution. However, the lattice strain was increased with Ce3+substitution in the NiZn ferrite lattice. The cations distributions study was determined using Bertaut method. Force constants at tetrahedral and octahedral sites were calculated from the FTIR studies. Saturation magnetization, remanent magnetization, coercivity, anisotropy constant (K) and Bohr magneton were evaluated from the magnetic hysteresis loops. Saturation, remanence, initial permeability and Bohr magneton were decreased whereas the coercivity was increased with Ce3+ doping. Yafet and Kittle (Y-K) angles were increased with Ce doped NiZn nanoferrites from x = 0 to x = 0.04 respectively. Switching field distribution (SFD) evaluations for Ce doped NiZn nanoferrites were determined by taking first derivative of the demagnetization data respectively. In conclusion, Single phase Ce doped NiZn nanoferrites have large magnetic saturation, remanence whereas other samples have higher coercivity accordingly. Ce-doped NiZn nanoferrites with varying structural and magnetic properties have potential applications in various fields such as switching, security, core, microwave absorption applications, nanofabrication and nanodevices.

SrCo2 W-type hexagonal nanoferrites with composition SrCo2-xZnxCeyFe16-yO27 (whereas x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 and y = 0, 0.02, 0.04, 0.06, 0.08, 0.1) were synthesized by sol-gel auto combustion method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM) and Vibrating sample magnetometer (VSM) were used to find out the structural, vibrational, morphological and magnetic properties of SrCo2 W-type hexagonal ferrites. Physical properties such as bulk density (Dbulk), X-ray density (Dxrd) and porosity (%P) of the SrCo2 W type hexagonal ferrites samples were calculated. Bulk density of the samples decreased whereas X-ray density increased with the Ce-Zn substitution in the W-type ferrites. Single phase samples of all the nanoferrites are achieved at the sintering temperature of 1050 °C. Structural parameters such as lattice parameters ‘a’ and ‘c’ were also calculated. Lattice parameter ‘a’ is found to be increased whereas ‘c’ is found to be decreased with the substitutions. Force constants at tetrahedral and octahedral sites are also evaluated which confirm the phase and substitution in W-type hexagonal ferrite. FESEM images showed homogenous and well crystallized at higher substitution of Ce-Zn in SrCo2 W-type hexagonal ferrites. Detailed magnetic parameters such as magnetic remanence coercivity, saturation, Bohr magneton, initial permeability, magneto crystalline anisotropy constant (K) and magnetic field anisotropy (Ha) were measured. Magnetic remanence decreased whereas coercivity, magneto crystalline anisotropy and field anisotropy increased in the SrCo2 W-type hexagonal ferrites samples. The dependence of Hc and Ha on the SrCo2 W-type hexaferrites may be due to the variations in the K and Ms of the substituted samples. Therefore, the prepared SrCo2 W-type nanoferrites with appropriate amount of metal cations are suitable candidate for the microwave devices and high frequency applications.

Co0.3Zn0.7Fe2O4 nanoparticles prepared by co-precipitation method were characterized by X-ray diffraction (XRD). Reduced graphene oxide (rGO) was prepared by modified Hummer's route and then characterized by UV–Visible and XRD techniques. Nano-heterostructures of Co0.3Zn0.7Fe2O4 with rGO were prepared using ultra-sonication technique. XRD analysis of Co0.3Zn0.7Fe2O4 nanoparticles and Co0.3Zn0.7Fe2O4-rGO confirmed the cubic structure of ferrite nanoparticles. Cyclic voltammetry experiments showed that Co0.3Zn0.7Fe2O4-rGO nano-heterostructures exhibit the greater value of specific capacitance (151.33 Fg−1) as compared to Co0.30Zn0.70Fe2O4 nanoparticles (91.20 Fg−1). These values of specific capacitance were observed at 10 mV s−1. Moreover, electrochemical impedance spectroscopy showed that Co0.3Zn0.7Fe2O4-rGO nano-heterostructures have lower charge transfer resistance than the bare Co0.3Zn0.7Fe2O4 nanoparticles. Electrochemical experiments illustrated that Co0.3Zn0.7Fe2O4-rGO nano-heterostructures have efficient energy storage properties and can be utilized for electrode's fabrication in supercapacitors.