In this study, we utilized quantum-mechanical calculations to explore the electronic structure of binary and ternary Fe-Al-based systems with noncollinear magnetic configurations. Our findings indicate that the ground state of systems, such as Fe9Al7, Fe9Al6B, Fe9Al6Ga, and Fe9Ga6, is not ferromagnetic, but rather exhibits a spin spiral structure in the [111] direction. We analyzed the effects of different types of exchange-correlation potentials, aluminum concentration, relaxation of interatomic distances, substituting atom positions, and spin wave orientations on magnetic properties. Various exchange-correlation potentials consistently demonstrated the dependency of the total energy on the spin spiral q-vector, with the generalized gradient approximation closely matching experimental observations. In the Fe9Al7 unit cell, a spin spiral structure prevails at 43.75% atomic Al, while other compositions favor ferromagnetism. The system can support spin spiral vectors in the [001], [110], and [111] directions, with [111] being the most energetically favorable. The equilibrium state is highly sensitive to the position and type of sp-elements within the unit cell. Overall, our results show that spin spiral structures with the [111] q-vector are energetically favored when the average magnetic moment is approximately 1 mu B per Fe atom, which is consistent with Mossbauer data.

The synthesis and the structural and magnetic characteristics of ternary nonstoichiometric Fe 65 – x Al 35 – y M x , y (M y = Ga, B, Sn; M x = V, Mn; x = 3, 5, 10 at %) compounds are experimentally and theoretically studied. Quantum-mechanical calculations of the energy of formation and an electronic structure explain the characteristic features of the phase transformations that occur during the synthesis and describe the experimentally observed changes in the magnetic parameters for various impurity elements.

Quantum mechanical calculations of the magnetic parameters in the ternary system Fe-Al-Ga for different contents of Al and Ga were carried out. The equilibrium values of the lattice constant, as well as the average values of magnetic moments and hyperfine magnetic fields were calculated. It was shown that the change in the magnetic parameters during the replacement of aluminum with gallium is mainly due to a change in the lattice parameter. The results obtained were compared with the experimental data.

Complexes Ln(TTA) 3 and [Ln(TTA) 3 · 1 ] (Ln = Eu, Gd; ТТА is thenoyltrifluoroacetyl-acetonate; 1 is 2-(5-chlorophenylene-2-hydroxy)-2-phenylethylene-bis(2-methoxy)phosphine oxide) in individual form, and as a part of a core of the polyelectrolyte stabilized colloids have been studied by Mössbauer spectroscopy and X-ray powder diffraction. The photophysical and colloidal characteristics of the solutions of polyelectrolyte nanoparticles were studied in water, artificial cerebrospinal fluid solution, solution of bovine serum albumin, and human blood serum. A stability of a luminescent response of the nanoparticles in solutions of bovine serum albumin and human blood serum at 37 °С for 2 hours has been revealed. This is a prerequisite for the potential application of studied nanoparticles for biovisualization.

The properties of the surface layer of core-shell nanoparticles incorporated into the matrix of macromolecules of 3,4-bis(decyloxybenzoyl) poly(propylene imine) derivative of the second generation are studied by Mössbauer spectroscopy at low temperatures. The spin states, the details of the phonon spectrum and the Debye temperature of surface layer atoms discussed.