Citrate Precursor Method Research Articles

Effect of Co concentration on cation distribution and magnetic and magneto-optical properties of CoxZn1-xFe2O4 nanoparticles synthesized with citrate precursor method

Effect of Co concentration on cation distribution and magnetic and magneto-optical properties of CoxZn1-xFe2O4 nanoparticles synthesized with citrate precursor method

Structural and magnetic characterizations of Co substituted Ni-Cu-Zn nanoferrites

Co substituted Ni-Cu-Zn nanoferrites with the compositional formula Cox Ni0.5−x Cu0.3 Zn0.2 Fe2O4 (where x=0.0, 0.1, 0.2) were synthesized by Citrate Precursor method. The as prepared samples were calcined at 950o C for 30 min using a conventional muffle furnace. Characterizations were carried out using XRD, FESEM and VSM techniques.XRD peaks conform to spinel type structure. FESEM micrographs showed surface morphology. Magnetic characterizations were carried out by employing VSM technique. This paper investigates the synthesized samples as potential electronic materials for Multilayer Chip Inductor (MLCI).

Influence of La3+-Co2+ substitution on X-band microwave absorption properties of Ba0.5Sr0.5Fe12O19 nanoparticles with insight into quarter wavelength phenomenon

The presented study aims to tune the microwave absorption properties by varying the chemical composition of Ba0.5Sr0.5Fe12O19 nanoparticles with Co–La substitution via the synthesis route of the sol-gel citrate precursor method. X-ray diffractograms (XRD) and Fourier Transformed Infrared Spectroscopy (FTIR) confirmed the formation of pure phase M-type hexagonal ferrite with varying lattice parameters. The permittivity measurements revealed increased dielectric losses, indicating good energy dissipation behavior. Enhancement of magnetic behavior resulted from the strengthened exchange interactions between lattice sites, leading to higher permeability values. Significant reflection losses were exhibited by our synthesized samples with a maximum reflection loss of −42.08 dB at 4.62 GHz for x = 0.35 at an experimental thickness of 3 mm. The dependence of reflection loss peaks on matching thickness was analyzed using calculated thickness profiles, revealing their close agreement with simulated thickness. The study highlighted the potential of synthesized samples for electromagnetic signature reduction, in both commercial and military applications.

Improvement in the structural, magnetic and electromagnetic behaviour of barium hexaferrites with yttrium doping for EMI shielding

Electromagnetic interference (EMI) shielding is critical for protecting electronic devices from interference generated by various sources such as power lines, radio waves, microwaves, and electronic devices. In this current study, we present a thorough investigation of the structural, magnetic, and electromagnetic properties of Y3+ doped M-type barium nano hexaferrites. Polycrystalline BaFe12−xYxO19 (x = 0.0, 0.3, 0.5, 0.7, and 0.9) hexaferrites are prepared using the citrate precursor method. The results of X-ray diffraction (XRD), Rietveld refinement and Raman spectroscopy confirmed that all samples have a single-phase, and pure hexagonal crystalline structure with space group P69/mmc. This result is consistent for all the prepared compositions. The structure and dopant materials in different chemical states of the sample are determined based on the X-ray photoelectron spectroscopy (XPS) spectrum. Field emission scanning electron microscopy (FESEM) analysis showed that the particles had a distinct hexagonal morphology. The chemical composition of the prepared hexaferrites is investigated using energy dispersive X-ray analysis (EDAX). UV spectroscopy showed an inverse relationship between the molar ratio of yttrium and the band gap. Vibrating sample magnetometer (VSM) results showed a decrease in saturation magnetization (Ms) and coercivity (Hc) with increasing fraction of yttrium ions. The shielding efficiency (SE) of the synthesized hexa materials against EMI is evaluated using a vector network analyser (VNA). In particular, effective EMI shielding was observed in the frequency spectra of 8–12 GHz (X-band region). Among the tested compositions, BaFe12–0.7Y0.7O19 with a thickness of 3 mm exhibited highest SE of 80.07 dB in the X-band region. The proposed yttrium-substituted barium M-type hexagonal ferrites exhibit significant reflection loss with enhanced absorption spectrum even when applied to an extremely thin 3 mm material, making it a possible preference as the radar-absorbed compound for EMI attenuators for weather monitoring, radar tracking, air traffic management, and gigahertz antennas. Furthermore, commercial applications including long-term magnetic media for recording, storing information, etc. are possible uses of the synthesised magnetic yttrium-doped barium M-type hexagonal ferrites.

Retrievable nano-sized Co–Mg–Zn ferrite as an active photocatalyst and adsorbent for removing organic and biological contaminants for water purification

The water contamination such as organic dyes and microbes raise global environmental concerns. The UV light-driven spinel ferrites are promising photocatalysts for water purification. In this present work, Co-doped Mg–Zn nanoferrites of composition Mg0.4Zn(0.6-x)CoxFe2O4 (x = 0–0.6 with step size 0.1) were successfully prepared by a wet chemical citrate precursor method. The potential of synthesized nanoferrites were tested for the removal of rhodamine B dye and Candida albicans fungi inhibition. The structural, morphological and optical studies were undertaken; wherein XRD examination confirmed the cubic spinel structure of the synthesized nanoferrites, with an average crystallite size between 27 and 38 nm. Scanning electron microscopy (SEM) disclosed that these ferrite nanoparticles have spherical shapes with nanometric particle size. The spinel structure of the produced nanoferrites was again shown by the bands at 523 and 407 cm−1 in the FTIR spectra. The band gap of 1.78–1.99 eV was confirmed by the Kubelka-Munk plots. The enhanced photocatalytic performance (95 %) for the Rhodamine B dye degradation was obtained due to the narrowing band gap (1.78eV) of Mg0.4Zn0.1Co0.5Fe2O4 ferrite nanoparticles. Also, this highest photocatalytic efficiency was attained at the maximum rate constant (k = 0.078 min−1). The mechanism involved in the photocatalysis process has been discussed. All the prepared nanoferrites exhibit an excellent antimicrobial effect on Candida albicans fungi with concentration x = 0.5 showing a better antimicrobial effect (76 %). Hence, these Co–Mg–Zn nanoferrites can act as active photocatalysts and adsorbents for removing organic and biological contaminants for water purification.

Synthesis and Characterization of Zr4+-Y3+ Substituted Ba-Sr Hexaferrite Nanoparticles for Microwave Absorption and Electromagnetic Shielding Applications

Novel compositions of Ba0.5Sr0.5Fe12-1.1xZrxY0.1xO19 (0.0≤x≤0.5) nanoparticles were synthesized using sol-gel citrate precursor method. X-ray diffraction confirmed the formation of magneto-plumbite hexagonal phase with average crystallite size of 55-70 nm. The fourier transformed infrared spectroscopy revealed the presence of metal cations vibrational modes in 460-600 cm−1 range. The Zr-Y contents influenced magnetic behavior and shielding properties with maximum total shielding effectiveness of -31 dB in K band, and -21 dB in X-band, observed for x=0.35. The microwave absorption studies revealed optimum reflection losses with maximum value of -32 dB at 6.4 GHz frequency for x=0.35. The obtained values validate the candidacy of Zr-Y substituted Ba-Sr hexaferrite nanoparticles for uninterrupted airborne surveillance, radar absorption and high frequency shielding applications.

Investigation of structural, elastic and magnetic properties of Cu2+ ions substituted cobalt nano ferrites

In the present work, we synthesized the Cu-doped CoFe2O4 (Co1-xCuxFe2O4) nanoparticles with × = 0.0, 0.2, 0.4 and 0.6, by employing the citrate precursor method. The X-ray Diffraction (XRD) pattern confirmed the pure cubic structure formation with the Fd-3m space group. To know the structural purity of each sample as well as the distribution of cations, Rietveld refinement was carried out. The crystallite size increases from 39.55 nm to 41.80 nm upto x = 0.2 and with further doping of Cu2+ ions it decreases to 36.27 nm. Similar variation is observed in the lattice parameter where the value of ‘a’ first increases from 8.378 Å to 8.381 Å and then decreases to 8.377 Å. The development of a non-uniform grain is seen using scanning electron microscope (SEM), which reveals the reduction in grain size. Fourier Transform Infrared Spectroscopy (FTIR) showed the two peaks v1 and v2 for all the samples around 541 cm−1 and 408 cm−1, respectively, which further decreases to 532.5 cm−1 and 402.5 cm−1 as the dopant ion concentration increases. The Stiffness constant, and Elastic modulus decrease with doping whereas, the Poisson’s ratio and Pugh’s ratio show a constant value of around 0.249 and 1.660, respectively. Vibrating Sample Magnetometer (VSM) analysis shows a decrease in saturation magnetization (σs) value from 76.85 emu/g to 43.62 emu/g. The net magnetic moment (nB) decreases from 3.29 μB to 1.85 μB and the effective anisotropy constant value decreases from 10.672erg/g to 4.461erg/g. Thus, the prepared nanoparticles provide a way forward for their industrial applications.

Comparison of rare earths doping (neodymium and samarium) on structural and magnetic properties of Ni–Zn–Bi nanoferrites

Excellent magnetic properties in ferrites are required for high-frequency applications and for wastewater treatment. Thus, the present study shows the comparison of magnetic and structural properties of Nd and Sm substituted Ni–Zn–Bi ferrites with the series Ni0.5Zn0.5Bi0.04NdxFe1.96–xO4 (with step size 0.002) and Ni0.5Zn0.5Bi0.04SmxFe1.96–xO4 (with step size 0.02) prepared using citrate precursor method. The impact of the substitution of rare earth ions (Nd and Sm) on magnetic properties of the synthesized samples is observed using a vibrating sample magnetometer (VSM). The saturation magnetization values enhance considerably from 52 to 58 emu/g for Nd3+ ions and 39 to 57 emu/g for Sm3+ ions, thus, making these materials magnetically hard. Further, the higher value of coercivity is also observed ranging from 133 to 167 Oe for Nd3+ ions and 81 to 155 Oe for Sm3+ ions. The shape of hysteresis loops indicates a super paramagnetic and ferromagnetic behavior in the obtained samples. The squareness ratio value is <0.5, suggesting the uniaxial anisotropy of particles and hence, these ferrites are suitable for microwave-absorbing and in permanent magnetic materials. The X-ray diffraction (XRD) pattern shows the formation of pure cubic crystallites, where, lattice parameters range from 0.840 to 0.839 nm and from 0.838 to 0.839 nm for Nd3+ and Sm3+ ions substitution, respectively. The crystallite size ranges between 28.63 to 29.89 nm and 18.33 to 26.23 nm, for substitution of Nd3+ and Sm3+ ions, respectively. Field emission scanning electron microscopy (FESEM) shows the formation of homogeneous grains, whereas, energy dispersive spectrometer (EDS) counts describe the purity of the samples. The Sm concentration x = 0.10 has the maximum surface area with value of 42.6 m2/g which proves to be having good data storage application due to high surface area. The zero-field cooled (ZFC) and field cooled (FC) data show that Nd-doped Ni–Zn–Bi nanoferrites show superparamagnetic behaviour in the room temperature range which makes them suitable for practical applications.

Short review on fabrication, structural and dielectric characterization of zirconium based oxide nanoparticles

Zirconum based oxide nanoparticles of general formula Ba1-xPbxZrO3 and Ba1-xSrxZrO3with dopant concentrations ranging from 0 to 1 using reverse micellar and polymeric citrate precursor methods are discussed. Presently, hundreds of dielectric materials have currently been synthesized. Zirconium-based oxides are the significant class of dielectric materials among them because of their structural flexibility and simplicity. This review summarizes recent advances in zirconium-based oxide synthetic strategies, their significant use as dielectric materials for wireless communication devices such as electroceramics and piezoelectric devices, and efforts being made to alter their physicochemical properties and increase their efficiencies by adjusting reaction conditions. The article's goal is to describe approaches controlling these materials' efficacy and upcoming difficulties for practical applications.1–3

Magnetic, Electrical and Humidity Sensing Properties of Multiferroic GdCrO3 Nanoparticles Fabricated by Metal Organic Precursor Method

AbstractMonophasic GdCrO3 nanoparticles have been fabricated by ethylene glycol‐assisted metal citrate precursor method. The as‐prepared nanoparticles have been characterized for phase purity, size and morphology by using powder X‐ray diffraction, transmission electron microscopy and scanning electron microscopic techniques. GdCrO3 nanoparticles showed excellent crystallinity with an average particle size of 78 nm and high specific surface area of 184 m2 g−1. The two band gap values of 1.9 eV and 2.3 eV were calculated using K−M function of the UV‐visible diffuse reflectance spectroscopy. Magnetic results of GdCrO3 nanoparticles possess the well defined ferromagnetic loop, which confirms the ferromagnetic characteristics of these nanoparticles. Our results further exhibit improved P−E loop for GdCrO3 nanoparticles showing ferroelectric behaviour at room temperature for the first time which indicates the presence of multiferroic nature. The dielectric constant and dielectric loss of sintered/unsintered pellet of GdCrO3 were measured as a function of frequency and temperature. Lastly, the humidity sensing parameters of GdCrO3 nanoparticles have also been reported.

Structure, morphology, sintering behavior, and microwave dielectric properties of 6Ca0.61Nd0.26TiO3–4Nd(Zn1/2Ti1/2)O3 ceramics prepared via citrate precursor method

Structure, morphology, sintering behavior, and microwave dielectric properties of 6Ca0.61Nd0.26TiO3–4Nd(Zn1/2Ti1/2)O3 ceramics prepared via citrate precursor method

Study on dielectric properties, electric modulus, and impedance spectroscopy of Ni–Ca ferrite nanoparticles

The dielectric properties of the Ni1-xCaxFe2O4 nanoparticles (x = 0.02, 0.04, and 0.1) synthesized by the citrate precursor method and sintered at two different temperatures, 600 °C and 1000 °C, were investigated by using a complex impedance technique in the range of 100 Hz to 5 MHz. Also, the temperature effect of the dielectric properties of the two sintered Ni0.9Ca0.1Fe2O4 samples at different frequencies was studied in the range of 313 K–773 K showing their semiconducting nature. The frequency dispersion of ε′, ε" and tanδ for all the samples is attributed to the interfacial polarization mechanism, which follows the Maxwell-Wagner model. The variation of the ac conduction in the samples depends primarily on the electron hopping between Fe3+↔Fe2+ ions and hole hopping between Ni2+↔Ni3+ ions in the octahedral sites. The Cole-Cole (Zʺ vs. Zʹ) plots characterize by two overlapping semicircles represented by an electrical circuit consisting of two parallel R–C in series, manifesting the grain and grain boundary effect on the electrical properties of the samples. The (Mʺ vs. Mʹ) plots insure the electric stiffness behavior of this type of ferrites. Moreover, in the present ferrite samples, the lower values of the σʹac, ε′, εʺ, and tanδ at high frequencies, make them suitable for use as an inductor-core for high-frequency power transformers for telecommunication purposes.

Electrical and Structural Properties of CuBa2LaCa2Cu4O11+δ Superconducting System

In this work, the superconducting CuBa2LaCa2Cu4O11+δ compound was prepared by citrate precursor method and the electrical and structural properties were studied. The electrical resistivity has been measured using four probe test to find the critical temperature Tc(offset) and Tc(onset). It was found that Tc (offset) at zero resistivity has 101 K and Tc (onset) has 116 K. The X-ray diffraction (XRD) analysis exhibited that a prepared compound has a tetragonal structure. The crystal size and microscopic strain due to lattice deformation of CuBa2LaCa2Cu4O11+δ were estimated by four methods, namely Scherer(S), Halder-Wagner(H-W), size-strain plot (SSP) and Williamson-Hall, (W-H) methods. Results of crystal sizes obtained by these methods were compared with each other. In all these methods, the values of βhkl (full-width half-maximum (FWHM) for diffraction peaks) and miler indices (hkl) are determined from the results obtained from Fullprof, Mach, Origin and VESTA software. The lattice parameters a, b and c, lattice shape, d and degree of crystallization were calculated. It was found that the crystal size which are calculating by S, W-H, SSP and H-W were (174.8472, 171.1776, 173.1009 and 175.4386) A0 respectively while the lattice strain values were (none, 0.0025, 0.004 and 0.003464), respectively.

Microstructural, electrical and magnetic properties of Ni-Zn nanoferrites sintered at high temperature

The nanoparticles of Ni1-xZnxFe2O4 (x = 0 and 0.5) were prepared via a citrate precursor method and sintered at 700 °C for 3 h. The structural, electrical and magnetic properties of nickel ferrites before and after substitution of zinc ions were studied using XRD (X-Ray Diffraction method), FTIR (Fourier Transform Infrared Spectroscopy), VSM (Vibrating Sample Magnetometer) and two probe method. The morphology of prepared samples was examined using SEM analysis. The Raman spectra confirmed the cubic spinel structures of prepared nanoparticles. The observed crystallite size and porosity of NiFe2O4 (38 nm and 43%) were higher for Ni0.5Zn0.5Fe2O4 (25 nm and 38%) nanoparticles. Electrical resistivity increased drastically from 3.31 × 108 Ωm to 2.52 × 109 Ωm for NiFe2O4 and Ni0.5Zn0.5Fe2O4 respectively. Specific saturation magnetization (34 emu/g (x = 0) and 63.65 emu/g (x = 0.5)), coercivity (389 Oe (x = 0) and 115 Oe (x = 0.5)) and remnant magnetization (12.62 emu/g (x = 0) and 12.36 emu/g (x = 0.5)) of ferrite nanoparticles were observed.

A comparative study of structural, electrical and dielectric properties of Ni-Zn and Co-Zn nanoferrites

Ni-Zn ferrite and Co-Zn ferrite having composition Ni0.5Zn0.5Fe2O4 and Co0.5Zn0.5Fe2O4 were synthesized using citrate precursor method. Single phase cubic spinel structure with space group Fd3m was confirmed by X-ray diffraction (XRD) studies of the prepared samples. The crystallite size was found to be 42 nm and 28 nm for Ni-Zn and Co-Zn nanoferrites respectively. The FTIR spectra showed the metal stretching vibrations at tetrahedral sites and octahedral sites for both the ferrites. The dielectric and electrical study was done to calculate various parameters like dielectric loss tangent and dc resistivity. The prepared ferrites are found to have good insulating properties due to high value of dc resistivity with values 5.39 × 1010 Ω-cm for Ni-Zn ferrite and 3.4 × 1010 Ω-cm for Co-Zn ferrite. Also, due to low value of loss tangent at high frequency i.e. 0.05 at 1 MHz for Ni-Zn nanoferrite, these ferrites may be used in the high frequency applications.

Effect of bismuth doped Ni-Zn nanoferrite on structural and magnetic properties

The citrate precursor method was used to investigate bismuth substituted Ni-Zn nanoferrites with content Ni0.5Zn0.5BixFe2-xO4 having step size 0.02. Bismuth was incorporated to Ni-Zn spinel ferrite in order to customize its properties. The XRD, VSM determined the structural and magnetic properties of the synthesized samples. The average crystallite size was determined to be between 15 and 28 nm. Except at x = 0.06, a tensile strain was found with a rise in bismuth content using the Williamson-Hall method. The dislocation density was found from 2.95 × 10−3 to 8.22 × 10−3 Å−2. The value of saturation magnetization varies from 57 to70 emu/g and retentivity was in the range 5 to17 emu/g. The squareness ratio of the prepared Bi doped nanoferrites sample has value less than 0.5 which reveals the single domain nature of the prepared materials. This occurrence of uniaxial anisotropy concluded that these ferrites can be used in microwave-absorbing and permanent magnetic material applications.

FT-IR study of Cu substituted Ni-Zn ferrites prepared by citrate precursor method

FT-IR study of Cu substituted Ni-Zn ferrites prepared by citrate precursor method

Comparative studies of the structural and electrical studies of conventional and microwave sintered Li0.35 Ni0.1Mn0.1Zn0.2Fe2.35O4 synthesized by the citrate precursor method

Comparative studies of the structural and electrical studies of conventional and microwave sintered Li0.35 Ni0.1Mn0.1Zn0.2Fe2.35O4 synthesized by the citrate precursor method

Synthesis of Ni-Zn-Mg-Zr spinel ferrites as high-performance electromagnetic wave absorber in Ku band

The present work deals with the magnetic characterization and microwave absorption characterization of magnesium and zirconium co-substituted nickel-zinc spinel ferrites (Ni0.6Zn0.4(MgZr)xFe2-2xO4; x = 0.05, 0.10, 0.15 and 0.20) synthesized through sol–gel citrate precursor method. The magnetic properties have been analysed using vibrating sample magnetometer (VSM) and the complex electromagnetic properties have been determined with the help of vector network analyser (VNA) in Ku band i.e., 12.4–18 GHz. The electromagnetic wave absorption analysis has been done by monitoring change in reflection loss (RL) values with increasing frequency and thickness of the samples. The minimum RL equal to −33.4 dB has been obtained for composition with x = 0.15 at a matching frequency of 17.21 GHz and matching thickness of 1.6 mm.

Influence of Mg doping on the structural, electrical and dielectric properties of Co-Zn nanoferrites

Mg-Co-Zn nanoferrites of composition MgxCo0.5Zn0.5Fe2−xO4 (x = 0.25, 0.5, 0.75 and 1.0) were successfully synthesized by using a citrate precursor method. After synthesis, the samples were examined using different techniques for structural, morphological, electrical and dielectric characterizations. All the samples were found to have single phase spinel cubic structure with Fd-3m space group in the X-ray diffraction spectroscopy (XRD) investigation. The value of average crystallite size ranged from 37 to 47 nm with the increase in Mg ion concentration from x = 0.25 to 1.0. The hopping lengths at tetrahedral and octahedral sites showed an increasing behaviour with increasing magnesium ion concentration. The presence of tensile strain in the samples was confirmed by W-H plots. The dielectric behaviour of the prepared nanoferrites was recorded at room temperature in the frequency range 10 kHz–10 MHz. The real part and imaginary part of the dielectric constant were found to be in the range 3.80–7.93 and 0.0036–0.644 at 1 MHz frequency and the value of loss tangent was 0.00095–0.081 at 1 MHz for the magnesium doped Co-Zn nanoferrites. The value of loss tangent decreased very sharply to remarkably low values at 10 MHz frequency. The dc resistivity value was found very low in the range 3.2 × 108 Ω-cm to 4.0 × 109 Ω-cm for different concentrations of Mg2+ ions in the samples. Due to such low losses at high frequency region and high value of dc resistivity, these materials can be considered as potential candidate for high frequency applications.