Structural, thermodynamic, and magnetic properties of SrFe12O19 hexaferrite modified by co-substitution of Cu and Gd.

A hard magnetic system of SrFe12O19 nanomaterial was modified according to the composition of Sr0.95Gd0.05Fe12-xCuxO19 with x = 0.0, 0.30, and 0.60 using the sol-gel technique. The structures of the samples were evaluated using X-ray diffraction (XRD) along with Rietveld refinement, and an M-type hexaferrite with a hexagonal structure was confirmed with a trace amount of the α-Fe2O3 phase. In addition, transmission electron microscopy (TEM) analysis revealed polycrystalline nanoplates in all samples. Furthermore, the bond structures of the octahedral and tetrahedral sites along with the thermodynamic properties of these ferrites were extracted from the FTIR spectra at room temperature. The Debye temperature (θD) decreased from 755.9 K to 749.3 K due to the co-substitution of Gd3+ at Sr2+ and Cu2+ at Fe3+. The magnetic hysteresis (M-H) measurements revealed that the coercivity decreased from 5.3 kOe to 1.5 kOe along with the highest magnetization saturation (Ms) of 65.2 emu g-1 for the composition Sr0.95Gd0.05Fe11.7Cu0.3O19, which is suitable for industrial application. The effect of local crystalline anisotropy in magnetization was explored using the law of approach to saturation (LAS). Finally, thermo-magnetization was recorded in the range from 400 K to 5 K for cooling under zero field and in the presence of a 100 Oe field, and magnetic transitions were tracked due to the introduction of the foreign atoms of Gd and Cu into SrFe12O19.

Exploration of the structural, vibrational, electronic, mechanical and thermal properties of Ru4Al3B2 and Ru9Al3B8: a DFT study.

The structural, dynamical, electro-optical, mechanical, and thermal characteristics of the newly synthesized intermetallic compounds Ru4Al3B2 and Ru9Al3B8 have been studied under ambient and elevated pressure through density functional theory (DFT). The obtained lattice parameters of the compounds are consistent with the experimental values. The metallic character of these compounds is established by the band structure and density of states (DOS). The electronic charge density distribution and bond analysis imply that Ru4Al3B2 and Ru9Al3B8 have mainly both ionic and covalent bonding. The non-negative phonon dispersion frequency of the compounds reaffirms their dynamical stability. Both compounds are tough as well as have high melting points, and hence, can be applied in harsh conditions. Mechanical properties are significantly improved under pressure. Thermal barrier coating (TBC) is a possible field of application for both compounds. The different thermal properties such as the Debye temperature (ΘD), Grüneisen parameter (γ), melting temperature (Tm), minimum thermal conductivity (Kmin) and lattice thermal conductivity (κph) of these compounds have been studied to figure out the suitable application areas in thermally demanding situations. The pressure and temperature dependent bulk modulus (B) and other thermodynamic properties have also been analyzed, which suggested that the present compounds are strong candidates for device applications at high temperature and pressure. Owing to their high optical absorptivity and reflectivity in the UV region, they are also candidates for UV-based applications. Furthermore, they also have applicability in the fields of electronics, aviation, energy storage, and supercapacitor devices for their superior electronic, thermal and mechanical properties.

Effect of yttrium(Y) on structural, morphological and transport properties of CdO thin films prepared by spray pyrolysis technique.

Cadmium oxide (CdO) and yttrium (Y) doped CdO (Y: CdO) thin films have been prepared onto glass substrate at temperature 300 °C by spray pyrolysis technique. The effects of yttrium (Y) doping on the structural, morphology, optical and electrical properties were studied systematically. The X-ray diffraction (XRD) study confirms that CdO films are polycrystalline in nature with cubic structure having lattice parameter of 0.4658 nm. Surface topographic and nano-structural analysis indicates cluster grain size and porosity decreased substantially with increase of yttrium (Y) content in CdO films. The optical transmittance exhibits excellent optical transparency, with an average transmittance of >70% in the visible range for 2 to 4% yttrium (Y) doping. The optical band gap widens in Y: CdO film from 2.24 to 2.62 eV through Burstein- Moss shift. Hall measurement confirms that material is of n type with a minimum resistivity of 4.7 × 10-4 Ω-cm with carrier concentration of 4.2 × 1021 cm-3 were achieved for 2% yttrium (Y) doping.