A5103249012- Layered Double Hydroxides Synthesis and Applications
- Boron and Carbon Nanomaterials Research
- Iron-based superconductors research
- Superconductivity in MgB2 and Alloys
- Magnesium Oxide Properties and Applications
- Graphene research and applications
- Rare-earth and actinide compounds
- Carbon Nanotubes in Composites
- Diamond and Carbon-based Materials Research
- Zeolite Catalysis and Synthesis
- Inorganic Fluorides and Related Compounds
- Advanced Chemical Physics Studies
- Chemistry Education and Research
- Magnetic properties of thin films
- High-pressure geophysics and materials
- Thermal Expansion and Ionic Conductivity
- Environmental Sustainability and Education
- Organic Light-Emitting Diodes Research
- Inorganic Chemistry and Materials
- Science and Education Research
- Science and Science Education
- Magnetism in coordination complexes
- Neural Networks and Applications
- Thermal and Kinetic Analysis
- Catalysis and Hydrodesulfurization Studies
Universidade Federal de Viçosa
2016-2024
Universidade Federal do Rio de Janeiro
2008-2018
International Iberian Nanotechnology Laboratory
2015
Universidade Federal de Juiz de Fora
2008-2012
Laboratoire de Spectrométrie Ionique et Moléculaire
2010
Université Claude Bernard Lyon 1
2010
Centre National de la Recherche Scientifique
2010
We propose a model to calculate the electronic structure of hydrotalcite-like compounds by using periodic boundary conditions and ab initio density functional theory (DFT). The proposed method build up layered double hydroxides (LDHs) was tested for Zn2/3Al1/3(OH)2Cl1/3·2/3H2O, Zn2/3Al1/3(OH)2(CO3)1/6·4/6H2O, Mg2/3Al1/3(OH)2(CO3)1/6·4/6H2O with 3R1 polytype. In model, occupation cationic sites in hydroxide layers is ordered interlayer anions water molecules form film between layers. Direct...
This ab initio study was performed to better understand the correlation between intercalated water molecules and layered double hydroxides (LDH), as well changes that occur by dehydration process of Zn−Al hydrotalcite-like compounds containing Cl− CO32− counterions. We have verified strong interaction among molecules, cointercalated anions, OH groups from hydroxyl layers is reflected in thermal stability these compounds. The Zn2/3Al1/3(OH)2Cl1/3·2/3H2O hydrotalcite loses all around 125 °C,...
The reaction of water molecules with the MgO(001) surface was studied density-functional theory using periodic boundary conditions for a better understanding about formation H+ and HO– ions on terrace through structural, barrier, thermodynamic studies. This process is relevant as initial hydroxylation step this surface, it part catalyzed hydrolysis mechanism.The geometries dissociation energies one, two, three adsorbed clean were obtained type adsorption assessed. Transition states processes...
We present density functional theory (DFT) calculations with periodic boundary conditions combined thermodynamic and kinetic analyses to study the changes in [Mg2/3Al1/3(OH)2](CO3)1/6·2/3H2O layered double hydroxide (LDH) over a temperature interval of 25–350 °C. The inspection five different hypotheses related decomposition reaction this material suggests mechanism: (1) contains H2O molecules up 180 (2) next step involves formation lamellar structure which CO32– anions are monodentate...
Linear carbon chains (LCCs) are the ultimate one-dimensional molecular system, and they show unique mechanical, optical, electronic properties that can be tuned by altering number of atoms, strain, encapsulation, other external parameters. In this work we probe effects quantum anharmonicity, finite size on structural vibrational these using high-level density-functional-theory calculations. We find strong anharmonicity for infinite chains, leading to ground-state nuclear wave functions...
Brucite-like mixed hydroxides of the general formula MgxM1−x(OH)2 for M = Zn, Cu or Ca were studied by density functional theory within pseudopotential approximation, plane waves basis set, and periodic boundary conditions. Geometrical parameters energy analysis done different compositions (different values x in previous formula). It is shown that substitution magnesium zinc copper leads to stable species several proportions, whereas a hydroxide containing Mg2+ Ca2+ predicted not be formed,...
The diffusion kinetics of hydrogen in bulk palladium and Pd nanoclusters containing up to 512 atoms has been theoretically investigated at 3% loading using ring-polymer molecular dynamics simulations. electronic ground-state energy surfaces are modeled an explicit many-body potential fitted reproduce the properties hydrides. constant, calculated by integration velocity autocorrelation function, shows Arrhenius behavior with inverse temperature. In addition, both prefactor activation found...
According to an earlier Abrikosov model, a positive, nonsaturating, linear magnetoresistivity (LMR) is expected in clean, low-carrier-density metals when measured at very low temperatures and under high magnetic fields. Recently, vast class of materials were shown exhibit extraordinary LMR but conditions that deviate sharply from the above-mentioned Abrikosov-type conditions. Such deviations are often considered within either classical Parish-Littlewood scenario random-conductivity network...
The recently discovered organic magnetoresistance effect (OMAR) reveals the spin-dependent behavior of charge transport in semiconductors. So far, it is known that hyperfine interactions play an important role this phenomenon and also spin-orbit coupling negligible for light-atom based compounds. However, presence heavy atoms, should OMAR. It these are responsible singlet triplet states mixing via intersystem crossing change spin-charge relaxation time mobility process. In work, we report a...
We investigated the pressure dependence of crystal structure CaAl
A promising branch of neuromorphic computing aims to perform cognitive operations in hardware leveraging the physics efficient and well-established nano-devices. In this work, we present a reconfigurable classifier based on network electrically connected magnetic tunnel junctions that categorizes information encoded amplitude input currents through spin torque driven magnetization switching output configuration. The can be trained classify new data by adjusting additional programming applied...
SrAl2Si2 crystallizes into either a semimetallic, CaAl2Si2-type, α phase or superconducting, BaZn2P2-type, β phase. We explore possible α→Pc,Tcβ transformations by employing pressure- and temperature-dependent free-energy calculations, vibrational spectral room-temperature synchrotron powder X-ray diffraction (PXRD) measurements up to 14 GPa using diamond anvil cell. Our theoretical empirical analyses together with all reported baric thermal events on both phases allow us construct...
Spin Transfer Torque Nano-Oscillators (STNOs) and Magnetic Memories (STT-MRAM) are the two best examples of Spintronic devices exploring spin transfer mechanism with a strong position to reach real world commercial applications. However, practical applications have requirements where performance STNOs is still not good enough. The most notable these need for larger output power (Pout ~ 1 μW required) narrow line-widths (Γ <; MHz). Among many different implementations STNOs, those based in...
Anais do Congresso Brasileiro Interdisciplinar em Ciência e Tecnologia (2764-0582) - Representatividade Negra No Ensino De Química: Utilizando Do Jogo Da Memória Para Dar Visibilidade Aos Químicos Negros E As Químicas Negras Presentes Na História Química
Linear carbon chains (LCCs) are the ultimate 1D molecular system and they show unique mechanical, optical electronic properties that can be tuned by altering number of atoms, strain, encapsulation, other external parameters. In this work, we probe effects quantum anharmonicity, strain finite size on structural vibrational these chains, using high$-$level density functional theory (DFT) calculations. We find strong anharmonicity for infinite leading to ground$-$state nuclear wavefunctions...