Papers by Sergio Ricardo de Lazaro
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Density Functional Theory Calculations, 2021
Applied Surface Science, 2021
Applied Surface Science, 2021
Abstract The MnMoO4 is an environment-friendly semiconductor material with exciting properties an... more Abstract The MnMoO4 is an environment-friendly semiconductor material with exciting properties and low cost to obtain highly employed supercapacitors. In this work, the α-MnMoO4 phase was investigated by a careful DFT approach providing a detailed description of the electronic, optical, structural, magnetic, and photocatalytic properties of the surfaces. The results provide interesting insights on surface properties at the molecular level and point out novel applications for the evaluated materials, such as the treatment of water effluents or clean energy obtainment from water splitting. The available morphologies for MnMoO4 were also investigated, enabling the tuning of material properties according to crystalline morphology.
Bulletin of Materials Science, 2021
Design and production of α-MnO 2 structures over carbonaceous material is considered as potential... more Design and production of α-MnO 2 structures over carbonaceous material is considered as potential strategy for improving electrochemical performance of supercapacitors. This study describes the development of a simple method for hydrothermal synthesis of a composite material with directly anchoring α-MnO 2 over a nanographite matrix. The nanographite matrix was obtained by electrochemical exfoliation of graphite rods (from depleted Leclanché batteries) and characterized by X-ray diffraction (XRD), Raman spectroscopy and field emission gun-scanning electron microscopy (FEG-SEM). The obtained results indicated that nanographite produced presented low levels of defects with a mild oxidized surface. This nanographite was used as anchoring base for producing MnO 2 particles, using the developed hydrothermal procedure. For paralleling, pure MnO 2 particles were also produced in same conditions. The prepared materials were characterized by XRD, Raman spectroscopy and FEG-SEM. XRD patterns proved formation of α-MnO 2 for pure and composite materials. Morphological characterization indicated the formation of nanoneedles in both situations; however, in the composite the α-MnO 2 was produced as smaller nanoneedles homogeneously spread over the nanographite surface. Raman spectra showed that the desired composition was achieved. Electrochemical characterization showed that the adopted strategy was successful in producing materials with improved pseudocapacitive performance, high reversibility, presenting specific capacitance of 279.8 F g −1 and coulombic efficiency of 99.7%.
Physical Chemistry Chemical Physics, 2020
Expulsion of p-tert-butylcalix[6]arene molecules from a monolayer in a biologically relevant pres... more Expulsion of p-tert-butylcalix[6]arene molecules from a monolayer in a biologically relevant pressure regime, π = 30 mN m−1, correlates with their lack of antibacterial activity.
The Journal of Physical Chemistry C, 2020
Precise control of the overall performance for solid-state materials is associated with morpholog... more Precise control of the overall performance for solid-state materials is associated with morphological modulations which provide an alternative way to the rational design based on understanding the corresponding electronic structures of the exposed surfaces. Experimental and theoretical efforts were combined herein to elucidate the structural-property relationship of CuMnO 2 nanoparticles from different morphologies. The microwave-assisted hydrothermal method was employed to synthesize these crystals with different morphologies, while firstprinciple quantum mechanical calculations were performed at the DFT level to obtain the structural, electronic, and magnetic properties of CuMnO 2 surfaces. Our structural results have confirmed a monoclinic structure for crednerite-type CuMnO 2 nanoparticles described by the Jahn-Teller distorted octahedral [MnO 6 ] clusters, which are connected by linear twofold [CuO 2 ]. FE-SEM images combined with Wulff construction analyses indicated that CuMnO 2 nanoparticles adopt a hexagonal nanoplate-like morphology which can enclose a major extent of the (100) surface with contributions from (101), (110) and (111) surfaces. Electronic structure and magnetic characterizations were discussed by the role of the corresponding electronic states of exposed surfaces which control the energy-level band diagram and spin density distribution. These results extend our fundamental understanding of the atomic processes which underpin the morphological modulations of the CuMnO 2 material, thus creating a new path to obtain selected nanoparticles with desirable properties which optimize their applications.
New Journal of Chemistry, 2019
Multiferroic materials are characterized by the existence of ferroic properties coupled in a sing... more Multiferroic materials are characterized by the existence of ferroic properties coupled in a single crystalline phase and represent great promise for the development of spintronics devices.
Revista Processos Químicos, 2015
Current Physical Chemistry, 2016
Journal of Luminescence, 2003
A polymeric precursor method was used to synthesize BaTiO 3 amorphous thin film processed at low ... more A polymeric precursor method was used to synthesize BaTiO 3 amorphous thin film processed at low temperature. The luminescence spectra of BaTiO 3 amorphous thin films at room temperature revealed an intense single-emission band in the visible region. The visible emission band was found to be dependent of the thermal treatment history. Photoluminescence (PL) properties for different annealing temperatures were investigated. It was concluded that the intensity of PL is strongly dependent on both the heat treatment of the films and the presence of an inorganic disordered phase. Experimental optical absorption measurements showed the presence of a tail. These results are interpreted by the nature of these exponential optical edges and tails, associated with defects promoted by the disordered structure of the amorphous material. We discuss the nature of visible PL at room temperature in amorphous barium titanate in the light of the results of recent experimental and quantum mechanical theoretical studies. Our investigation of the electronic structure involved the use of first-principle molecular calculations to simulate the variation of the electronic structure in the barium titanate crystalline phase, which is known to have a direct band gap, and we also made an in-depth examination of amorphous barium titanate.
Journal of Alloys and Compounds, 2009
Química Nova, 2012
Recebido em 24/6/11; aceito em 27/11/11; publicado na web em 20/1/12 SURFACE ENERGY FOR (001) TiO... more Recebido em 24/6/11; aceito em 27/11/11; publicado na web em 20/1/12 SURFACE ENERGY FOR (001) TiO 2 NANOSURFACES. In this work was made an investigation about bulk and surface models (at maximum 20 layers) of the TiO 2 material in the (001) direction. TiO 2 commercial sample was feature using XDR technique to determine phase and crystallites average size. Bulk and (001) surface models were simulated for TiO 2 material using DFT/B3LYP and its results were used for calculating energy surface, electronic levels, superficial atomic displacement and charge maps. Atoms of the first and second layers of the slab model showed electronic densities very well organized in the form of chains or wires.
Journal of Alloys and Compounds, 2021
Abstract In the present work, we have carried out experimental analysis along with first-principl... more Abstract In the present work, we have carried out experimental analysis along with first-principles density functional theory (DFT) calculations to understand the magnetic ground state of Fe doped Mn2O3. The analysis of structural properties show that the orthorhombic type of crystal structure with space group Pcab is preserved, but the unit cell volume decreases with an increase in Fe concentration. Magnetic susceptibility measurements show that two antiferromagnetic transitions (TN1 = 25 K, TN2 = 80 K) for undoped Mn2O3 merged into one at around 35 K with increasing concentration of Fe doping (Mn2−xFexO3; x = 0; 0.20; 0.50; 0.75). M-H curve at 5 K exhibits small hysteresis around the origin. The magnitude of magnetization increases with the increasing concentration of Fe. M-H curve at 100 K shows the linear behavior of M concerning H for x = 0.20 and x = 0.50, indicating the paramagnetic state of the sample. As a complement to the experimental analysis, first-principles calculations using DFT were carried out. Fe doping was simulated by the corresponding substitution of Mn atoms to reproduce stoichiometric features of Mn2−xFexO3. The agreement between the two approaches suggests that the magnetic ground state of Fe doped Mn2O3 is tunable with Fe concentration.
International Journal of Quantum Chemistry, 2020
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Papers by Sergio Ricardo de Lazaro