ABSTRACTThe stability of the Ti50Pd50-xRux alloy was investigated using first-principles density functional theory within the plane-wave pseudopotential method. Firstly, the Ti50Pd50 gave equilibrium lattice parameter and lowest heats of formation in better agreement with experimental data to within 3%. The heat of formation decreases with an increase in Ru concentration, consistent with the trend of the density of states which is lowered at the Fermi level as Ru content is increased which suggests stability. It was also found that from the calculated elastic constants the structures showed positive shear modulus above 20 at. % Ru, condition of stability. Furthermore, the addition of Ru was found to strengthen the Ti50Pd50-xRux system at higher concentrations. The thermal coefficients of linear expansion for the Ti50Pd31.25Ru18. 75 are higher at low temperature, and that the TiPd-Ru system tends to expand more at low content of 18.75 at. % Ru than at higher content. Partial substitution of Pd with Ru was found more effective as a strengthening element and may enhance the martensitic transformation temperature of the Ti50Pd50 alloy.

More recently, the L10 MnPt alloy has received massive attention in data storage applications such as spintronics due to its high ferromagnetic stability and very high Néel temperature. It was found that L10 MnPt alloy showed ferromagnetic behaviour at room temperature. In this study, the effect of introducing antiferromagnetic (Cr) and ferromagnetic (Fe) elements on MnPt alloy is being investigated using density functional theory (DFT). The thermodynamic stability was determined from the heats of formation to check the formability of Pt50Mn50-xMx (M= Cr, Fe; x=6.25, 12.5, 18.75, 25) alloys. These Pt50Mn50-xMx alloys were found to be thermodynamically stable although with lower heats of formation. Overall magnetic moments decrease slightly with an increase in Cr and Fe compositions, only at 6.25 at. % Cr the ferromagnetic state is improved when the c/a ratio is 1.10. The current work revealed that the DFT-based first-principle approach can be used to design new possible compositions for the development of PGM-bearing magnetic materials.

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Magnetic functional materials remain an area of research interest for applications in electronic devices. Among these materials, Mn50Pt50 alloy has received a great deal of attention in practical potential applications such as spintronics due to its high-thermal and magnetic stability. It was reported previously that L10 Mn50Pt50 alloy shows ferromagnetic ordering at room temperature. In this study, the effect of the partial substitution of Pt with Co was investigated using density functional theory (DFT) approach. The thermodynamic, magnetic and mechanical properties were determined to check the stability of Mn50Pt50-xCox alloys. The results showed that the L10 phase has the lowest heat of formation when the c/a ratio is 1.10 for 6.25 at.% Co. Overall magnetic moments improve with an increase in Co compositions when the c/a ratio is 1.10. The obtained results reveal that Mn50Pt50-xCox alloys exhibit attractive magnetic and mechanical properties for future magnets in spintronics applications. Graphical Abstract

Monazite, as a source of raw materials, plays a significant role in the development and applications of green technologies, including medicine and energy production. It contains nuclear materials, which are challenging to extract by convectional cracking processes. However, a new method (thermal plasma cracking) has been proposed for processing monazite. The first principles calculation approach was used to investigate the theoretical structure and mechanical properties of monazite-systems to gain deeper understanding of monazite's thermodynamics and mechanical structure. The calculated lattice parameters were found to correlate well with obtained experimental values and that these monazite type systems are exceptionally mechanically stable. The results also show that there are imaginary soft modes in dispersion curves which may correspond to negative elastic constant C35 indicating vibrational instability.