Analysis of Cd2+ and In3+ ions doping on microstructure, optical, magnetic and mo¨ssbauer spectral properties of sol-gel synthesized BaM hexagonal ferrite based nanomaterials

Precise studies of cadmium and indium doped barium hexagonal ferrites having chemical composition Ba0.7Nd0.3Cdx/2Inx/2Fe12-xO19 (x = 0.0, 0.1, 0.2, 0.3) have been performed by sol-gel auto-combustion method in which ethylene glycol was used as a gel precursor. The structural, morphological, optical, elemental and magnetic properties have been studied by using various techniques like XRD, FESEM, FTIR, EDS and VSM. The XRD patterns shows characteristic (110), (008), (107), (114), (108), (203), (205), (206), (1011), (300), (217), (2011), (220), (2014) peaks along with the presence of secondary phase confirming the formation of hexagonal structure with an average crystallite size of 43–59 nm. FESEM supports the formation of hexagonal, dense and agglomerated nanoparticles. The Vibronic study using infrared radiation was carried by FTIR analysis reveal the various configuration modes with hexagonal symmetry of prepared nanoparticles. The magnetic measurements have been studied at room temperature indicates that saturation magnetization (Ms) and magnetic moment (nB) found to be of range 40–86 emu/g and 7.97–17.23 μB. The precise magnetic studies made it possible to reveal that saturation magnetization (Ms) increases with the cadmium and indium concentration for x = 0.1 and after that it decreases for x = 0.2, 0.3 which may be due to the difference in the magnetic moments of Cd, In and Fe ions. Due to high value of saturation magnetization (Ms), it can be used for applications in the field of high density recording storage devices and also, this magnetic change has been explained on the basis of exchange interactions. The room temperature Mo¨ssbauer spectra of all the nano-sized materials shows normal Zeeman splitting consisting of six merged line patterns which indicates the formation of ferromagnetic phase that supports the magnetic properties. Keywords: Barium neodymium nanoparticles, Sol-gel, Structural and optical analysis, Magnetic measurements, Mo¨ssbauer spectr

Structural, microstructural and magnetic properties of NiFe2O4, CoFe2O4 and MnFe2O4 nanoferrite thin films

The structural, microstructural and magnetic properties of nanoferrite NiFe2O4 (NF), CoFe2O4 (CF) and MnFe2O4 (MF) thin films have been studied. The coating solution of these ferrite films was prepared by a chemical synthesis route called sol–gel combined metallo-organic decomposition method. The solution was coated on Si substrate by spin coating and annealed at 700 °C for 3 h. X-ray diffraction pattern has been used to analyze the phase structure and lattice parameters. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been used to show the nanostructural behavior of these ferrites. The values of average grain's size from SEM are 44, 60 and 74 nm, and from AFM are 46, 61 and 75 nm, respectively, measured for NF, CF and MF ferrites. At room temperature, the values of saturation magnetization, Ms∼50.60, 33.52 and 5.40 emu/cc, and remanent magnetization, Mr∼14.33, 15.50 and 1.10 emu/cc, respectively, are observed for NF, CF and MF. At low temperature measurements of 10 K, the anisotropy of ferromagnetism is observed in these ferrite films. The superparamagnetic/paramagnetic behavior is also confirmed by χ′(T) curves of AC susceptibility by applying DC magnetizing field of 3 Oe. The temperature dependent magnetization measurements show the magnetic phase transition temperature

Investigation of super-exchange interactions in BaHoxFe12-xO19 (0.1 <= x <= 0.4) nanohexaferrites and exploration at ultra high frequency region

BaHoxFe12-xO19 (x=0.1, 0.2, 0.3, 0.4) nanohexaferrites were successfully synthesized for the first time by sol-gel auto-combustion technique. X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDAX) were utilized to investigate the different structural parameters and elemental composition. Incorporation of Ho3+ ions increased the dc resistivity while a decrease in the saturation magnetization (M-s), 66.68-57.08 emu/g, followed by decrease in Curie temperature (766.83-758.15 K), exchange integral (J), and anisotropy was observed. The obtained values of M-s. were found to be very high as compared to the values reported in the bulk form. The dielectric constant (epsilon') and dielectric loss tangent (tan delta) were investigated as a function of frequency and the behavior is explained on the basis of Maxwell-Wagner model and Koop's theory. Additionally, a maiden attempt was made to explore the BaH(o)xFe(12-x)O(19) nanohexaferrites at ultrahigh frequencies and observed ultra-low magnetic loss (0.004-0.01) and dielectric loss (0.004-0.06)

Remarkable magnetization with ultra-low loss BaGdxFe12-xO19 nanohexaferrites for applications up to C-band

Sol-gel synthesized BaGdxFe12-xO19, (x=0.0, 0.1, 0.2, 0.3) nanohexaferrites, have been explored for magnetic and microwave properties. X-ray diffraction studies revealed the hexagonal structure of the synthesized ferrites. The particle size was observed to be in the range 90-84 nm. The dc resistivity was found to be increasing with an increase in Gd3+ content and the variation of dc resistivity with temperature confirmed the semiconducting behavior of all nanohexaferrites. The observed values of saturation magnetization and coercivity, at room temperature, are 81.34 emu/g and 6020 Oe respectively which are very high as compared to the values ever reported till date. Additionally, we observed ultra low magnetic loss (0.004-0.01) and dielectric loss (0.004-0.06) over the GHz frequency region. The obtained results make these nanohexaferrites a competent material for antenna applications up to C-band

Superparamagnetic behaviour and evidence of weakening in super-exchange interactions with the substitution of Gd3+ ions in the Mg-Mn nanoferrite matrix

The Gd3+ substituted Mg-Mn nanoferrites with generic formula Mg0.9Mn0.1GdxFe2-xO4 (x = 0.05, 0.1, 0.2, 0.3) have been prepared for the first time by self-ignited solution combustion method. The X-ray analysis confirmed the formation of single phase cubic spinel structure. Gd3+ substitution has resulted in an increase in the crystallite size (13.4-16.1 nm) and lattice parameter (8.35-8.38 angstrom). The M-H and ZFC-FC study revealed that all nanoferrites are of superparamagnetic in nature. The saturation magnetization (M-s) has been observed to decrease with the incorporation of Gd3+ ions. The cation's distribution has been estimated by using the magnetic characterization method. The magnetic properties such as initial permeability (mu(i)) and magnetic loss tangent (tan delta) have been investigated as a function of frequency. The initial permeability has been observed to be almost constant with frequency and in each nanoferrite an onset of resonance is observed. In addition, very low values of 'tan delta' were obtained

Structural, magnetic and Mossbauer study of BaLaxFe12-xO19 nanohexaferrites synthesized via sol-gel auto-combustion technique

BaLaxFe12-xO19 (0.05 <= x <= 0.25) nanohexaferrites were synthesized by sol gel auto combustion method. X-ray diffraction study revealed the hexagonal structure of the synthesized nanoferrites without any secondary phase and Rietveld analysis confirmed the P63/mmc space group. The crystallite size was observed to increase (49-63 nm) with the increasing substitution of La3+ ions. The particle size was observed to be in the range 49-63 nm. The remarkable increase in saturation magnetization upto 78.5 emu/g and an increase in magneto-crystalline anisotropic was observed with the increase in La3+ substitution. In addition, for the first time we have reported the Mosssbauer study of BaLaxFe12-xO19 nanohexaferrites in the present paper

Self-ignited synthesis of Mg-Gd-Mn nanoferrites and impact of cation distribution on the dielectric properties

Mg0.9Mn0.1GdxFe2-xO4 nanoferrites were processed for the first time by a solution combustion technique. X-ray diffraction studies revealed the spinel cubic structure of the synthesized ferrites. The particle size was observed to increase (13-16 nm) with an increase in Gd3+ ion content The cation distribution is inferred from the X-ray diffraction. It is observed from cation distribution that Gd3+ ions preferred octahedral (B) sites. The DC resistivity was found to be increasing with an increase in Gd3+ content The dielectric constant epsilon' and loss tangent (tan delta) was observed to decrease with the addition of Gd3+ content as well as with the increase in frequency. The variations in DC resistivity as well as dielectric constant with the increasing substitution of Gd3+ ions have been correlated to the cation distribution. The very high values of DC resistivity (similar to 10(8) Omega cm) and low values of loss tangent (0.9-0.008) are the prime achievements of this work