Role of Surfaces in the Magnetic and Ozone Gas-Sensing Properties of ZnFe2O4 Nanoparticles: Theoretical and Experimental Insights

The magnetic properties and ozone (O₃) gas-sensing activity of zinc ferrite (ZnFe₂O₄) nanoparticles (NPs) were discussed by the combination of the results acquired by experimental procedures and density functional theory simulations. The ZnFe₂O₄ NPs were synthesized via the microwave-assisted hydrothermal method by varying the reaction time in order to obtain ZnFe₂O₄ NPs with different exposed surfaces and evaluate the influence on its properties. Regardless of the reaction time employed in the synthesis, the zero-field-cooled and field-cooled magnetization measurements showed superparamagnetic ZnFe₂O₄ NPs with an average blocking temperature of 12 K. The (100), (110), (111), and (311) surfaces were computationally modeled, displaying the different undercoordinated surfaces. The good sensing activity of ZnFe₂O₄ NPs was discussed in relation to the presence of the (110) surface, which exhibited low (-0.69 eV) adsorption enthalpy, promoting reversibility and preventing the saturation of the sensor surface. Finally, the O₃ gas-sensing mechanism could be explained based on the conduction changes of the ZnFe₂O₄ surface and the increase in the height of the electron-depletion layer upon exposure toward the target gas. The results obtained allowed us to propose a mechanism for understanding the relationship between the morphological changes and the magnetic and O₃ gas-sensing properties of ZnFe₂O₄ NPs.

Surface and morphological studies of LiNbO3: p-type semiconductivity on stoichiometric surfaces

The surface and morphological properties of LiNbO3 surfaces were calculated, and particular semiconductor types for crystal morphologies were found.

Structural, vibrational and electronic properties of the superconductor CuxTiSe2: theoretical and experimental insights

The crystal/electronic structure and vibrational properties of the CuxTiSe2 intercalation compounds were studied combining experimental and theoretical techniques. The Cu added into the TiSe2 matrix was characterized as an intercalant atom into van der Waals gaps from Raman spectroscopy analysis. Theoretical and experimental data indicate the Cu-intercalation effect on the crystalline structure as a local disorder affecting [TiSe6] clusters from SeSe layers, which results in a volume expansion. A significant charge transfer from Cu atoms to the host lattice results in a change from Ti4+ to Ti3+ species, narrowing the band-gap and increasing the superconductivity of the material.

Synthesis, antimicrobial activity and advances in structure-activity relationships (SARs) of novel tri-substituted thiazole derivatives

Trisubstituted thiazoles were synthesized and studied for their antimicrobial activity and supported by theoretical calculations. In addition, MIC, MBC and MFC were also tested. Moreover, the present study was analyzed to scrutinize comprehensive structure-activity relationships. In fact, LUMO orbital energy and orbital orientation was reliable to explain their antibacterial and antifungal assay. Amongst the tested compounds, tri-methyl-substituted thiazole compound showed higher antimicrobial activity and low MIC value due to highest LUMO energy.

The role of exchange–correlation functional on the description of multiferroic properties using density functional theory: the ATiO3 (A = Mn, Fe, Ni) case study

In this study, ab initio density functional theory calculations were performed on ATiO₃ (A = Mn, Fe, Ni) materials for multiferroic applications.

Photoelectrochemical and theoretical investigation of the photocatalytic activity of TiO2 : N

In N-doping on TiO₂ nanomaterial occurs a big decrease of band-gap (1 eV); however, its photocatalysis is low. We clarify such fact from effective mass, i.e., the electron–hole recombination is more than creation of electron–hole pair.