In this work, the Al3+-Sm3+ substituted M-type Ba–Sr hexaferrites, having a composition of Ba0.4Sr0.6Al0.4-xSmxFe11.60O19 (BSAMFO; Pure, 0.0 ≤ x ≤ 0.4) were synthesized using the sol-gel technique. ...To achieve the hexagonal phase, the optimum annealing temperature was measured by the TGA analysis. X-ray diffraction (XRD) was employed to identify the phase of magnetic powders (MPs). The XRD pattern reveals that the MPs with Al3+ and Sm3+ contents (for x ≤ 0.4) represent α-Fe2O3 as a second phase and the MPs (with 0.1 ≤ x ≤ 0.4) show the presence of a small amount of FeSmO3 phases. Fourier transform infrared spectroscopy (FTIR) and XRD examination clearly expose the different band modes in structure, formation and the compositions of the hexagonal structure, whereas scanning electron microscopy (SEM) was employed to examine the morphologies of the MPs. The hexagonal platelet-like shape with size 0.54–1.23 µm of MPs is observed by SEM images. The presence of ferrite elements is confirmed by energy dispersive spectrometer (EDS) analysis. The magnetic characteristics of MPs were analyzed by a physical property measurement system-vibrating sample magnetometer (PPMS-VSM). Results reveal that Al3+-Sm3+ substitutions modify the saturation magnetization (Ms), a remanant magnetization (Mr) and coercivity (Hc). Additionally, the Hc value decreased while Ms and Mr exhibited the monotonic behavior as the function of x.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Food security concerns and the scarcity of new productive land have put productivity enhancement of degraded lands back on the political agenda. In such a context, salt‐affected lands are a valuable ...resource that cannot be neglected nor easily abandoned even with their lower crop yields, especially in areas where significant investments have already been made in irrigation and drainage infrastructure. A review of previous studies shows a very limited number of highly variable estimates of the costs of salt‐induced land degradation combined with methodological and contextual differences. Simple extrapolation suggests that the global annual cost of salt‐induced land degradation in irrigated areas could be US$ 27.3 billion because of lost crop production. We present selected case studies that highlight the potential for economic and environmental benefits of taking action to remediate salt‐affected lands. The findings indicate that it can be cost‐effective to invest in sustainable land management in countries confronting salt‐induced land degradation. Such investments in effective remediation of salt‐affected lands should form part of a broader strategy for food security and be defined in national action plans. This broader strategy is required to ensure the identification and effective removal of barriers to the adoption of sustainable land management, such as perverse subsidies. Whereas reversing salt‐induced land degradation would require several years, interim salinity management strategies could provide a pathway for effective remediation and further showcase the importance of reversing land degradation and the rewards of investing in sustainable land management.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The influence of Cu substitution on the structural and morphological characteristics of Ni–Zn nanocrystalline ferrites have been discussed in this work. The detailed and systematic magnetic ...characterizations were also done for Cu substituted Ni–Zn nanoferrites. The nanocrystalline ferrites of Cu substituted CuxZn0.5−xNi0.5Fe2O4 ferrites (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) were synthesized using sol gel self-combustion hybrid method. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM) were used to investigate the properties of Cu substituted nanocrystalline ferrites. Single phase structure of Cu substituted in Ni–Zn nanocrystalline ferrites were investigated for all the samples. Crystallite size, lattice constant and volume of the cell were found to increase by increasing Cu contents in spinel structure. The better morphology with well-organized nanocrystals of Cu–Zn–Ni ferrites at x=0 and 0.5 were observed from both FESEM and TEM analysis. The average grain size was 35–46nm for all prepared nanocrystalline samples. Magnetic properties such as coercivity, saturation, remanence, magnetic squareness, magneto crystalline anisotropy constant (K) and Bohr magneton were measured from the recorded M–H loops. The magnetic saturation and remanence were increased by the incorporation of Cu contents. However, coercivity follow the Stoner-Wolforth model except for x=0.3 which may be due to the site occupancy and replacement of Cu contents from octahedral site. The squareness ratio confirmed the super paramgnetic behaviour of the Cu substituted in Ni–Zn nanocrystalline ferrites. Furthermore, Cu substituted Ni–Zn nanocrystalline ferrites may be suitable for many industrial and domestic applications such as components of transformers, core, switching, and MLCI’s due to variety of the soft magnetic characteristics.
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•Cu substituted ZnNi nanoferrites were synthesized using sol gel self-combustion.•Crystallite size, lattice constant and volume of the cell were increased by increasing Cu contents.•Bohr magneton magneto crystalline anisotropy constant and saturation magnetization were evaluated.•Saturation magnetization was also calculated by using LoA.•CuZnNi Nanocrystalline ferrites can be used for transformers, core, switching, and MLCI’s applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Summary
Density‐functional theory based, first‐principles spin‐polarized calculations of the structural, electronic, magnetic, optical, and thermoelectric characteristics of K2OsX6 (X = Cl, Br) are ...presented. Structural optimization confirms the stability of these compounds in ferromagnetic phase with curie temperatures of 726 K (K2OsCl6) and 557 K (K2OsBr6). The calculated formation and cohesive energies present K2OsX6 compounds as thermodynamically stable and strongly bonded. Computed electronic properties explore both the compounds as half‐metallic. In the spin‐up channel, they exhibit semiconducting nature, having direct band gap values of 2.69 eV (K2OsCl6) and 2.1 eV (K2OsBr6), while in spin‐down configuration, they turn into metals. The calculated ferromagnetic total spins magnetic moment per formula unit is 2.00 μB for both the compounds with major contributions from Os‐t2g states. The reasonable values of optical parameters like optical conductance, absorption factor, refractive index, and reflectivity potentially dedicate these compounds for optoelectronic applications. The calculated positive Seebeck coefficient with maximum values of 76.4 μV/K, for K2OsCl6, and 99.9 μV/K, for K2OsBr6, represent these compounds as p‐type materials. The proposed compounds may achieve consideration in spintronic, thermoelectric, and optoelectronic devices.
Spintronics is basically different from conventional electronics, where besides the state of charge, the spin channels of electrons are also used as additional degree of freedom for efficiency of data transfer and storage. However, presently, the major problem is that the spin‐based polarizability is insufficient for insertion into semiconductors, which makes it an important aspect of research to find out high spin‐polarized materials. Therefore, inorganic cubic perovskite‐related K2PtCl6 type materials, K2OsX6 (X = Cl, Br), were investigated for the stated purpose. These materials were found as half metallic ferromagnets, having excellent optical and thermoelectric properties.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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•Magnesium based spinel ferrites were successfully synthesized by sol-gel method.•Dielectric constant shows the normal spinel ferrites behavior.•The dc conductivity are found to ...decrease with increasing temperature.•The samples with low conductivity have high values of activation energy.•The Impedance decreases with increasing frequency of applied field.
Spinel ferrites with nominal composition MgPryFe2−yO4 (y=0.00, 0.025, 0.05, 0.075, 0.10) were prepared by sol-gel method. Temperature dependent DC electrical conductivity and drift mobility were found in good agreement with each other, reflecting semiconducting behavior. The dielectric properties of all the samples as a function of frequency (1MHz–3GHz) were measured at room temperature. The dielectric constant and complex dielectric constant of these samples decreased with the increase of praseodymium concentration. In the present spinel ferrite, Cole–Cole plots were used to separate the grain and grain boundary’s effects. The substitution of praseodymium ions in Mg-based spinel ferrites leads to a remarkable rise of grain boundary’s resistance as compared to the grain’s resistance. As both AC conductivity and Cole–Cole plots are the functions of concentration, they reveal the dominant contribution of grain boundaries in the conduction mechanism. AC activation energy was lower than dc activation energy. Temperature dependence normalized AC susceptibility of spinel ferrites reveals that MgFe2O4 exhibits multi domain (MD) structure with high Curie temperature while on substitution of praseodymium, MD to SD transitions occurs. The low values of conductivity and low dielectric loss make these materials best candidate for high frequency application.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The study of microscopic effects on the dispersion of surface magnetoplasmon polaritons is important. We use the collisionless Vlasov equation and Maxwell’s equations to evaluate the dielectric ...tensor for evaluating the dispersion relations of surface magnetoplasmon polaritons. We treat the case in the Voigt geometry assuming a semi-infinite dielectric medium. The direction of the magnetic field is considered parallel to the surface and perpendicular to the propagation vector k. The analysis shows the influence of additional microscopic kinetic effects. Standard Drude model results are retrieved in the absence of these effects.
The ground state electronic structure and absorption efficiency of α-Be3X2 (X = N, P or As) and their alloys are investigated using density functional theory. All pristine compounds and alloys are ...found to have direct band gaps at the zone center Γ point. The Be24PxN16-x and Be24AsxN16-x alloys (x = 4, 8, 12, or 16) are predicted to have suitable band gaps for solar absorber applications. The majority interband electronic transitions in the pristine compounds and the alloys are between the valence band p-states of N, P and As and the conduction band p-states of Be. The alloy systems show strong and wide absorption spectra, suggesting potential solar energy conversion applications.
•Be3N2 determined as a wide band gap above the visible region.•Be3P2 and Be3As2 have smaller band gap values in the IR region.•By doing of N into the Be3P2 and Be3As2 band gap effectively engineered.•Interband transitions results major peaks in the optical spectra of the compounds.•The device absorption efficiencies showed potential applications in solar cells.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
The present article reports a comprehensive study on structural, elastic, mechanical, acoustical, electronic and thermodynamic properties of XPdF3 (X = Rb, Tl). This study has been carried out using ...Wien2k computational code written in Fortran language and based on density functional theory. The obtained results explored the ground state stability of these compounds in non magnetic phase. The calculated structural properties including lattice constant, bulk modulus, ground state energy, energy of formation were compared with available literature. In addition, from elastic constants, bulk, shear and elastic moduli, Poisson's ratios and anisotropy factors were calculated. Furthermore, from criteria of Pugh's ratio and Cauchy pressure, the materials were found as ductile. The sound velocities in TlPdF3 were examined as lower than RbPdF3 because of comparatively heavier mass of Tl than Rb atom. The obtained electronic properties give the indications of inclusion of these compounds in category of metallic perovskites. Moreover, the thermodynamic parameters like thermal expansion, heat capacity, Debye temperature and Grüneisen parameter were computed using Debye model.
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