Khalid Mujasam Batoo

Microstructural and Mössbauer properties of low temperature synthesized Ni-Cd-Al ferrite nanoparticles

We report the influence of Al3+ doping on the microstructural and Mössbauer properties of ferrite nanoparticles of basic composition Ni0.2Cd0.3Fe2.5 - xAlx O4 (0.0 ≤ x ≤ 0.5) prepared through simple sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray, transmission electron microscopy (TEM), Fourier transformation infrared (FTIR), and Mössbauer spectroscopy techniques were used to investigate the structural, chemical, and Mössbauer properties of the grown nanoparticles. XRD results confirm that all the samples are single-phase cubic spinel in structure excluding the presence of any secondary phase corresponding to any structure. SEM micrographs show the synthesized nanoparticles are agglomerated but spherical in shape. The average crystallite size of the grown nanoparticles was calculated through Scherrer formula and confirmed by TEM and was found between 2 and 8 nm (± 1). FTIR results show the presence of two vibrational bands corresponding to tetrahedral and octahedral sites. Mössbauer spectroscopy shows that all the samples exhibit superparamagnetism, and the quadrupole interaction increases with the substitution of Al3+ ions.

Giant energy harvesting potential in (100)-oriented 0.68PbMg1/3Nb2/3O3–0.32PbTiO3 with Pb(Zr0.3Ti0.7)O3/PbOx buffer layer and (001)-oriented 0.67PbMg1/3Nb2/3O3–0.33PbTiO3 thin films

This work emphasis on the competence of (100)-oriented PMN–PT buffer layered (0.68PbMg1/3Nb2/3O3–0.32PbTiO3 with Pb(Zr0.3Ti0.7)O3/PbOx buffer layer) and (001)-oriented PMN–PT (0.67PbMg1/3Nb2/3O3–0.33PbTiO3) for low grade thermal energy harvesting using Olsen cycle. Our analysis (based on well-reported experiments in literature) reveals that these films show colossal energy harnessing possibility. Both the films are found to have maximum harnessable energy densities (PMN–PT buffer layered: 8 MJ/m3; PMN–PT: 6.5 MJ/m3) in identical ambient conditions of 30–150°C and 0–600 kV/cm. This energy harnessing plausibility is found to be nearly five times higher than the previously reported values to date.

Application Oriented Selection of Optimal Sintering Temperature from User Perspective: A Study on K0.5Na0.5NbO3 Ceramics

This work presents a novel user oriented approach that can relate materials science with technological applications in a more transparent, systematic and efficient manner. We have made an attempt to figure out the optimal (corresponding to best combination of material properties) sintering temperature of K0.5Na0.5NbO3 (KNN) for transducer and electrical energy storage applications. The weights and priority of vital physical properties for applications understudy are calculated using the quality function deployment (QFD) method. Losses (tanδ), charge storage properties (ϵr, Pr and EC) and elastic compliance (sE12 and sE11) are found to have negative priority for transducer application while in the other case d31, tanδ, sE12 and sE11 are spotted to have negative priority. Priority order for transducer and energy storage application is d31>kp>QM>Tc>tanδ>ϵr>Pr=EC=sE12=sE11>ρ and ϵr>d31=tanδ>sE12=sE11>Tc>Pr>EC>kp>ρ>QM, respectively. Finally, 1080°C (transducer) and 1120°C (capacitor) are the found to be the most appropriate solutions among the alternatives under using modified analytic hierarchy process (AHP).

Ferroelectric and magnetic properties of Nd-doped Bi4 − xFeTi3O12 nanoparticles prepared through the egg-white method

Multiferroic behavior of Bi4 − xNdxFeTi3O12 (0.0 ≤ × ≤ 0.25, × = 0.05) ceramic nanoparticles prepared through the egg-white method was investigated. The dielectric properties of the samples show normal behavior and are explained in the light of space charge polarization. Room temperature polarization-electric field (P-E) curves show that the samples are not saturated with maximum remanence polarization, Pr = 0.110 μC/cm2, and a relatively low coercive field, Ec = of 7.918 kV/cm, at an applied field of 1 kV/cm was observed for 5% Nd doping. The room temperature M-H hysteresis curve shows that the samples exhibit intrinsic antiferromagnetism with a weak ferromagnetism. These properties entitle the grown nanoparticles of BNFT as one of the few multiferroic materials that exhibit decent magnetization and electric polarization.

Electronic structure and magnetic properties of the Ni0.2Cd0.3Fe(2.5-x)A1(x)O4 (0 < or = x < or = 0.4) ferrite nanoparticles.

The structural, magnetic, and electronic structural properties of Ni0.2Cd0.3Fe(2.5-x)Al(x)O4 ferrite nanoparticles were studied via X-ray diffraction (XRD), transmission electron microscopy (TEM), DC magnetization, and near-edge X-ray absorption fine-structure spectroscopy (NEXAFS) measurements. Nanoparticles of Ni0.2Cd0.3Fe(2.5x)Al(x)O4 (0 < or = x < or = 0.4) ferrite were synthesized using the sol-gel method. The XRD and TEM measurements showed that all the samples had a single-phase nature with a cubic structure, and had nanocrystalline behavior. From the XRD and TEM analysis, it was found that the particle size increases with Al doping. The DC magnetization measurements revealed that the blocking temperature increases with increased Al doping. It was observed that the magnetic moment decreases with Al doping, which may be due to the dilution of the sublattice by the doping of the Al ions. The NEXAFS measurements performed at room temperature indicated that Fe exists in a mixed-valence state.

Synthesisation, electrical and magnetic properties of Al doped nano ferrite particles

Single phase cubic spinel nanocrytalline particles of Al doped Ni0.2Cd0.3Fe2.5O4 has been synthesised by sol-gel method with an average crystallite size of ∼5 nm. The dielectric constant (e′) and ac conductivity (σac) shows normal behaviour with frequency. The dielectric properties and ac conductivity in the samples have been explained in the light of Koops phenomenological theory. The impedance analysis shows that grain boundary volume increases with Al doping. ac susceptibility measurements show that the blocking temperature decreases with the Al doping. The variation of blocking temperature in the real and imaginary part of ac susceptibility shows the existence of non-linear phase.

Role of indium in controlling the magnetic properties of bulk and nano magnetic systems

ABSTRACT In the present ferrites (soft & hard) series, Saturation Magnetization, increases only at lowers concentration of Indium. The cation distribution from Mössbauer analysis indicates that Indium ion at lower concentration (10 to 20%) goes to tetrahedral site only, whereas higher concentration it goes octahedral sites also. Magnetization has been explained on the basis of super exchange hyperfine interactions as well as cation distribution of magnetic ions as per the Neels two sub lattice model of ferromagnetism. In all the chosen ferrite series magnetic behavior is consistent with substitution of dopant (In3+ ions). Ferromagnetic results are further authenticated by Mössbauer Spectroscopic analysis.

Interdependence between electrical and magnetic properties of polycrystalline cobalt-substituted tungsten bronze multiferroic ceramics

Polycrystalline cobalt-substituted tungsten bronze ferroelectric ceramics with chemical composition Ba5CaTi2−xCoXNb8O30 (x=0.00, 0.02, 0.04 and 0.08) were synthesized by solid state reaction technique. X-ray diffraction (XRD) technique was used to confirm the phase formation and it revealed the formation of single phase tetragonal structure with space group P4bm. The surface morphology of the samples was studied by using the scanning electron microscopy (SEM) technique. The dielectric properties such as dielectric constant and dielectric loss have been investigated as a function of temperature and frequency. The P–E and M–H studies confirmed the coexistent of ferroelectricity and magnetism at room temperature. The P–E loop study indicated an increase in the coercive field while the M–H study depicted a decrease in the magnetization with the incorporation of cobalt ions.

Synthesis and characterization of Y and Sm doped Mg nanoferrites

ABSTRACT Magnesium nano ferrite substituted with Yttrium and Samarium is synthesized by Sol Gel Auto Combustion method by optimising the sintering temperature and its duration to achieve pure Spinel Phase without any impurity. Particle size obtained from XRD and TEM are in close agreement with each other. Saturation magnetization of Mg-nanoferrite is moderate at room temperature which decreases by substitution of Y &Sm. Magnetic results are further authenticated by Mössbauer Spectroscopic analysis. Experimental results are explained on the basis of existing theories and Models. Magnesium ferrite (substituted with Y &Sm) is chosen because of its potential application in biomedical fields e.g, hyperthermia treatment, drug delivery and even for antibacterial activity.

Room temperature long range ferromagnetic ordering in Ni0.58Zn0.42Co0.10Cu0.10Fe1.8O4 nano magnetic system

The structural and magnetic behavior of sol-gel autocombustion synthesized nanocrystalline Ni0.58Zn0.42Co0.10Cu0.10Fe1.8O4 have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), Mӧssbauer spectroscopy and vibrating sample magnetometer(VSM). Sample of high purity and high homogeneity was obtained by calcination at low temperature (500°C) resulting in nanoparticles of average diameter ∼15nm as determined by XRD and further confirmed by TEM. X-ray diffraction (XRD) and selective area diffraction (SAED) confirmed the single phase of the sample. Mӧssbauer results are supported by magnetization data. Well defined sextets and appearance of hysteresis at room temperature indicate the existence of ferromagnetic coupling at room temperature finding material utility in magnetic storage data. The existence of iron in ferric state confirmed by isomer shift is a clear evidence of improved magnetic properties of the present system.