Tl₂HgGeSe₄ crystal was successfully, for the first time, synthesized by the Bridgman-Stockbarger technology, and its electronic structure and peculiarities of optical constants were investigated using both experimental and theoretical techniques. The present X-ray photoelectron spectroscopy measurements show that the Tl₂HgGeSe₄ crystal reveals small moisture sensitivity at ambient conditions and that the essential covalent constituent of the chemical bonding characterizes it. The latter suggestion was supported theoretically by ab initio calculations. The present experiments feature that the Tl₂HgGeSe₄ crystal is a high-resistance semiconductor with a specific electrical conductivity of σ ∼ 10^-8 Ω^-1 cm^-1 (at 300 K). The crystal is characterized by p-type electroconductivity with an indirect energy band gap of 1.28 eV at room temperature. It was established that a good agreement with the experiments could be obtained when performing first-principles calculations using the modified Becke-Johnson functional as refined by Tran-Blaha with additional involvement in the calculating procedure of the Hubbard amendment parameter U and the impact of spin-orbit coupling (TB-mBJ + U + SO model). Under such a theoretical model, we have determined that the energy band gap of the Tl₂HgGeSe₄ crystal is equal to 1.114 eV, and this band gap is indirect in nature. The optical constants of Tl₂HgGeSe₄ are calculated based on the TB-mBJ + U + SO model.

A series of glasses of the composition 20Na2-O-15CaO-5B₂O₃-5SiO₂-(55 - x) P₂O₅:xMnO₂, was prepared and characterized by XRD, DSC, SEM, and Raman techniques. The samples were later immersed in simulated body fluid (SBF) for checking the potential growth of hydroxyapatite layer (HA). Experiments confirmed that addition of manganese oxide leads to structural changes of the glasses. With increasing content of MnO₂, the surface of the samples became more congenial for improving the growth of HA. The formation of HA layer on the surface of the samples was confirmed just after seven days of immersion. The growth rate of HA has gradually increased with the increase of MnO₂content.

Increasing research interests have been paid to developing efficient multifunctional material systems (MFMS) by using various composite materials, owing to their useful properties and good stability. Here, we systematically studied 1-naphthols, especially how the type and position of a substituent influence the reactivity and properties, using different electron-directing groups. During computations, important preparation guidelines for thiol derivatives of 1-naphthol were obtained. It is very interesting to note that some molecules could exhibit intramolecular O–H–O interactions. Careful theoretical investigation reveals that all the tested compounds are stable and the molecules with substituents in positions 4 and 8 are the least reactive. It is also worth noting that for the stability and polarizability tensor values, it is more favorable when both substituents are in the same benzene ring. Among tested 1-naphthols, the greatest values of alpha, beta, and gamma are more than 5, 60, and 110 times better respectively, than in the urea molecule; the change of electron-withdrawing group (EWG) to electron-donating group (EDG) increases NLO effects. This study provided a new scope of 1-naphthols applicability by using them as anti-corrosion materials and as very good materials for NLO devices due to the high stability of the aromatic structure coupled with polarity given by the substituents. Also, the understanding of IR vibrations for more complex organic compounds with thiol substituent has been improved.

The series of ceramics with a host composition corresponding to popular 45S5 bioglass doped with manganese ions was prepared using the modified sol-gel technique with a citric acid as a catalyst. The same line of ceramics, for the first time in the case of bioactive glasses or ceramics, was obtained in the procedure applying an addition of a plant extract – aloe vera one -as a surfactant to get more porous material. The structure and properties of the glasses were characterized with SEM, XRD, DSC, Raman and IR spectroscopy. All samples, regardless the Mn ions concentration, are bioactive as it was shown by in vitro immersion in artificial plasma – increase of manganese content improves the bioactivity of the material. The addition of aloe vera gel leads to a significant increase in the surface porosity of the samples; its scale is correlated with content of the aloe vera. Studies reveal that Mn exists in tetrahedral positions coordinating oxygen and reducing concentration of NBO. An addition of aloe vera change this situation lowering cross-linking of the ceramic glassy host. Amount of aloe vera in the presence of Mn dopant plays an important role in speeding the growth of phosphate compounds layers. The phosphorous layer growth during immersion in SBF is both quicker and more intense in the case of material prepared with the plant extract. This study reveal, using Raman 3D mapping, that the HpA is not located only at the surface of the samples but also in the volume and that its volume concentration is bigger than the surface one.