Sukhenko I. Electronic structure of lead and calcium apatites, doped with transition metals and carbonate ions.

Sukhenko I. V. Electronic structure of lead and calcium apatites, doped with transition metals and carbonate ions. –– Qualification scientific work in the form of manuscript. Thesis for doctor of philosophy degree in speciality 105 –– . –– IMP NASU, Kyiv, 2025. The crystal-chemical versatility and the wealth of functional properties of apatite-like compounds, represented by the general formula Me10(XO4)6Y2, underpin their broad applicability in materials science and technology. This dissertation systematically investigates the structural, electronic, and magnetic properties of several classes of apatites, with particular emphasis on a detailed theoretical and experimental analysis of copper-substituted lead apatites. Using density functional theory (DFT) methods, complemented by DFT+U and parameters U, J obtained from first-principles constrained random phase approximation (cRPA) calculations, the work identifies promising candidates with potentially nontrivial electronic and magnetic behavior, paving the way for their further exploration in superconductivity, magnetism, and correlated electronic phenomena. In summary, this dissertation presents a multiscale investigation of the structural, electronic, and magnetic properties of apatites, focusing on carbonate substitution, cation doping, and especially copper-substituted lead apatites. Theoretical calculations, supported by experiments, demonstrate the ability to engineer significant property changes through targeted atomic substitution. The identification of stability criteria, structural distortions, magnetic interactions, and flat-band features in copper-substituted apatites underscores their potential for exploring novel electronic phases and developing next-generation functional materials.