Computational Study of A15 Ru-Based Alloys for High-Temperature Structural Applications

The structural, magnetic, electronic and elastic properties of A15 X3Ru (X = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) binary alloys are investigated using first-principles density functional theory (DFT) methods. Ru-based alloys have attracted remarkable research interest due to their unique properties, which make them suitable for high-temperature structural applications. In this chapter, the properties of several A15 Ru-based alloys are investigated in order to select the best suitable alloy/s for aerospace application. Heats of formation are calculated to determine the thermodynamic stability of the materials. Knowledge of the values of elastic constants is essential for understanding the mechanical properties of the materials. From our calculated elastic constants, the bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, melting temperature, anisotropic factor and the ratio B/G are determined. The electronic density of states are calculated and discussed. Lastly, the magnetic properties of A15 X3Ru alloys are studied. Thermodynamically stable Mn3Ru possesses high-magnetic moment compared to other X3Ru alloys, these results could pave way to experimental realization (synthesis) of Mn3Ru material.

From Single-Core Nanoparticles in Ferrofluids to Multi-Core Magnetic Nanocomposites: Assembly Strategies, Structure, and Magnetic Behavior

Iron oxide nanoparticles are the basic components of the most promising magnetoresponsive nanoparticle systems for medical (diagnosis and therapy) and bio-related applications. Multi-core iron oxide nanoparticles with a high magnetic moment and well-defined size, shape, and functional coating are designed to fulfill the specific requirements of various biomedical applications, such as contrast agents, heating mediators, drug targeting, or magnetic bioseparation. This review article summarizes recent results in manufacturing multi-core magnetic nanoparticle (MNP) systems emphasizing the synthesis procedures, starting from ferrofluids (with single-core MNPs) as primary materials in various assembly methods to obtain multi-core magnetic particles. The synthesis and functionalization will be followed by the results of advanced physicochemical, structural, and magnetic characterization of multi-core particles, as well as single- and multi-core particle size distribution, morphology, internal structure, agglomerate formation processes, and constant and variable field magnetic properties. The review provides a comprehensive insight into the controlled synthesis and advanced structural and magnetic characterization of multi-core magnetic composites envisaged for nanomedicine and biotechnology.

5-Fold symmetry in superatomic scandium clusters: exploiting favourable orbital overlap to sequester spin

5-Fold symmetry axes in scandium clusters localise same spin electrons. This explains the anomalously high magnetic moment of scandium clusters with 5-membered rings and clarifies the role of d-electrons in the formation of superatomic states.

Theoretical Studies of the Structural, Electronic and Magnetic Properties of the CoFeCeZ (Z = P, As and Sb) Quaternary Heusler Alloys

In this paper, we investigate the structural, electronic and magnetic properties of CoFeCrZ ([Formula: see text], As,Sb) quaternary Heusler alloy, using the first-principles full potential linear muffin-tin orbital (FP-LMTO) method within the spin gradient generalized approximation (GGA) for the exchange and correlation potential. Our results demonstrate that in ferromagnetic phase, the all alloys CoFeCrZ are stable in type-1 configuration and are half-metallic ferromagnets (HMF) with gaps of 0.99[Formula: see text]eV, 0.57[Formula: see text]eV and 0.70[Formula: see text]Ev, respectively. The obtained negative formation energy shows that CoFeCrZ alloys have strong structural stability. The calculated total magnetic moment, [Formula: see text] for all alloys exhibit Slater-Pauling rule, [Formula: see text]. At zero pressure, the three alloys shown 100% spin-polarization at Fermi–level [Formula: see text] with high Curie temperatures [Formula: see text]. Our calculation indicate also that the half-metallicity and high magnetic moment of CoFeCrP, CoFeCrAs and CoFeCrSb are robust against the lattice compression (up to 7.80%, 5.40% and 11%, respectively). On the basis of these results, it is suggested that the CoFeCrZ Heusler could be suitable for spintronics devices applications.