LUCIANO FABRICIO DIAS PEREIRA

LUCIANO FABRICIO DIAS PEREIRA

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Cobalt doping effects in zinc oxide
2024 - PEREIRA, LUCIANO F.D.; FERREIRA, WANDERSON L.; CORREA, BRUNO S.; COSTA, MESSIAS S.; COSTA, CLEIDILANE S.; FILHO, ARNALDO A.M.; SALES, TATIANE S.N.; BOSCH-SANTOS, BRIANNA; SCHELL, JULIANA; BURIMOVA, ANASTASIA; SAXENA, RAJENDRA N.; CABRERA-PASCA, GABRIEL A.; CARBONARI, ARTUR W.
In this paper, we investigate the solubility effects of Co in ZnO (Zn1−xCoxO, where x = 0, 0.03, 0.05, 0.1, 0.2, 0.25, 0.4, 0.8, and 1) by combining the results of perturbed angular correlation (PAC) spectroscopy using highly diluted 111Cd as probe nuclei and ab initio calculations based on spin-density functional theory (SDFT). This combined approach enables us to characterize the local structure around Cd ions, where, through PAC technique, it was possible to measure the EFG as a function of temperature and Co concentration and thereby monitor the changes in the structure and the Co solubility threshold in ZnO and the ZnO/CoO/Co3O4 mixed phase. The full-potential linear augmented plane wave plus local orbital (APW+lo) formalism were used here to describe the electronic structure of the supercells, including the atomic relaxations. These Ab initio calculations show an interesting behavior of the Cd and Co impurity levels in the band structure of ZnO, which explains the experimental results in terms of the origin of EFG and the evidence of ferromagnetic response.
Low temperature synthesis of pure and Fe-doped HfSiO4: Determination of Si and Fe fractions by neutron activation analysis
2019 - SALES, T.N.S.; BOSCH-SANTOS, B.; SAIKI, M.; BURIMOVA, A.; PEREIRA, L.F.D.; SAXENA, R.N.; CARBONARI, A.W.
A new method of synthesis of hafnium silicate HfSiO4 (also known as hafnon) is reported. We observed a selfcontrolled incorporation of SiO2 from the quartz tube in which a sample of hafnium oxide nanoparticles was heated. This approach was then adapted to Fe-doped hafnon production. Sample structure, morphology and composition were characterized by X-ray diffraction, electron microscopy and neutron activation analysis. Diffraction data has shown that lattice parameters of doped HfSiO4 thus obtained are very close to those previously known for bare hafnon. The hafnon-like phase stabilized at T=900 °C which is about 500 °C lower than the corresponding transition of bare bulk hafnium silicate. The fractions of Si and Fe in the composite matrices were determined with neutron activation analysis. These results completed by X-ray diffraction data allowed to assume that (i) Fe initially substituted Hf in the HfO2 lattice; (ii) there was no migration of iron atoms from Hf to Si sites at the formation of hafnon-like phase; (iii) doped and undoped hafnium oxide has taken as much Si from the quartz as was needed for the arrangement of Fe1-xHfxSiO4 tetragonal system, 0≤x<0.2. Our results are consistent with those obtained for similar materials, such as metal (Fe,V) doped zircon, where the dopant also demonstrated catalytic effect on phase stabilization.
Stable tetragonal phase and magnetic properties of Fe-doped HfO2 nanoparticles
2017 - SALES, T.S.N.; CAVALCANTE, F.H.M.; BOSCH-SANTOS, B.; PEREIRA, L.F.D.; CABRERA-PASCA, G.A.; FREITAS, R.S.; SAXENA, R.N.; CARBONARI, A.W.
In this paper, the effect in structural and magnetic properties of iron doping with concentration of 20% in hafnium dioxide (HfO2) nanoparticles is investigated. HfO2 is a wide band gap oxide with great potential to be used as high-permittivity gate dielectrics, which can be improved by doping. Nanoparticle samples were prepared by sol-gel chemical method and had their structure, morphology, and magnetic properties, respectively, investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with electron back scattering diffraction (EBSD), and magnetization measurements. TEM and SEM results show size distribution of particles in the range from 30 nm to 40 nm with small dispersion. Magnetization measurements show the blocking temperature at around 90 K with a strong paramagnetic contribution. XRD results show a major tetragonal phase (94%).
Charge distribution and hyperfine interactions in the vicinity of impurity sites in Insub(2)Osub(3) doped with Fe, Co and Ni
2015 - SENA, C.; COSTA, M.S.; MUNOZ, E.L.; CABRERA PASCA, G.A.; PEREIRA, L.F.D.; MESTNIK FILHO, J.; CARBONARI, A.W.; COAQUIRA, J.A.H.
First principles calculation of the Cd-doped ZrInsub(2): a study of electronic properties and electric field gradients
2014 - PEREIRA, L.F.D.; CAVALCANTE, F.H.M.; BAGGIO-SAITOVITCH, E.; FONTES, M.B.; SAINTOVITCH, H.; MESTNIK FILHO, J.; CARBONARI, A.W.
Defects in NTD silicon studied by evaporated and diluted sup(111)Cd probe nuclei by means of perturbed angular gamma-gamma correlation technique
2007 - CORDEIRO, MOACIR R.; CARBONARI, ARTUR W.; SAXENA, RAJENDRA N.; MERCURIO, MARCIO E.; PEREIRA, LUCIANO F.D.
Estudo do gradiente de campo elétrico e da estrutura eletrônica do ZnO dopado com Co e Cd e do HfOsub(2) dopado com Ta por cálculos de primeiros princípios
2011 - PEREIRA, LUCIANO F.D.
Characterization of nanostructured HfOsub(2) films using RBS and PAC
2012 - CAVALCANTE, F.H.M.; GOMES, M.R.; CARBONARI, A.W.; PEREIRA, L.F.D.; ROSSETTO, D.A.; COSTA, M.S.; ALVES, E.; BARRADAS, N.P.; FRANCO, N.; REDONDO, L.M.; LOPES, A.M.L.; SOARES, J.C.
Dynamic hyperfine interactions in sup(111)In((sup(111)Cd)-doped ZnO semiconductor: PAC results supported by ab initio calculations
2012 - MUNOZ, EMILIANO L.; MERCURIO, MARCIO E.; CORDEIRO, MOACIR R.; PEREIRA, LUCIANO F.D.; CARBONARI, ARTUR W.; RENTERIA, MARIO