ANASTASIA BURIMOVA

ANASTASIA BURIMOVA

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Molybdenum (II) acetate as a precursor for molybdenum trioxide
2024 - SOUZA, KATIUSSE S. de; SILVA, CRYSTIAN W.C. da; BURIMOVA, ANASTASIA; PEREIRA, LUCIANO F.; OTUBO, LARISSA; CARBONARI, ARTUR W.; FREITAS, RAFAEL S. de
Transition metal structures (such as cobalt, nickel, and molybdenium) have been the subject of studies in recent years due to their electrical, catalytic and magnetic properties. Orthorhombic molybdenum trioxide (α-MoO3) is relevant because it is an antioxidant material, leading to its catalytic properties that are influenced by the valence state of molybdenum ions and the local environment where they are inserted. These structures have been investigated in developments of sensors, energy storage and the formulation of gels for the treatment of chronic diseases [1]. In this perspective, the present work proposes the use of the molybdenum (II) acetate as a metallic precursor for obtaining α-MoO3 structures by the thermal decomposition method [2]. The Mo (II) acetate belongs to a group of metal complexes composed of two highly correlated Mo ions, in which each cations are connected to complexes containing oxygen. This reagent could favor, in specific chemical route, the crystallization of MoxOy [2][3]. The syntheses yields were characterized by X-ray diffraction (XDR), scanning electron microscopy (SEM), and energy-dispersive analysis (EDS). The X-ray diffraction results suggested α-MoO3 crystallite of the 77 nm (by the Scherrer equation). By means of microscopy analysis were observed that the obtained morphology is microrod-like, with a of approximately 774 nm and a length of the 37 micrometers. The EDS analysis only showed energies related to molybdenum (Mo) and oxygen (O), confirming the purity of the obtained material.
Perturbed angular correlation technique applied for studies of formation hafnon structures of HfSiO4 at different temperatures
2024 - SALES, T.S.N.; BURIMOVA, A.; PEREIRA, L.F.D.; FILHO, A.A.M.; CORREA, B.S.; SCALISE, L.; FERREIRA, W.L.; SOUZA, K.S.; RIBEIRO-JUNIOR, I.S.
Synthesis of the metavanadate CaV2O6 by the sol-gel method and the characterization by X-ray diffraction and time-differential perturbed gamma-gamma angular correlation techniques
2024 - MAZIVIERO, R.; PEREIRA, L.F.D.; BURIMOVA, A.; MIRANDA-FILHO, A.A.; PEREIRA, A.S.; SAXENA, R.N.; CARBONARI, A.W.
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.
Local crystalline structure of doped semiconductor oxides characterized by perturbed angular correlations
2022 - BURIMOVA, ANASTASIA; CARBONARI, ARTUR W.; LIMA, NICOLE P. de; MIRANDA FILHO, ARNALDO A.; SOUZA, ALEXANDRE P. dos S.; SALES, TATIANE da S.N.; FERREIRA, WANDERSON L.; PEREIRA, LUCIANO F.D.; CORREA, BRUNO S.; SAXENA, RAJENDRA N.
Doping semiconductor oxides with trace amounts of non-native elements can improve their properties such as bandgap and conductivity. The lack of local techniques makes the precise characterization of these materials difficult. Among the few techniques capable of providing local characterization, those based on hyperfine interactions at probe nuclei have the advantage of being well established, probing the material homogeneously and completely, thus investigating different regions of material. Some of these techniques are also quite sensitive even at extremely low dopant concentrations. The perturbed angular correlation technique, combined with first-principles calculations, has recently been shown to be a powerful method for characterizing doped semiconductor oxides. In this paper, we present a brief review of the unique information extracted from the semiconductor investigation with such a complex approach, including semiconductor oxides doped with cadmium and other elements. A strong relationship between the local environment, including electronic structure, and the nature of the dopant and the native element of the doped oxides is also shown.
DFT-based Calculations of the Magnetic Hyperfine Interactions at Cd Sites in RECd Compounds with the FP-LAPW ELK Code
2020 - SCALISE, LEVY; BURIMOVA, ANASTASIA; PEREIRA, LUCIANO F.; FERREIRA, WANDERSON; SALES, TATIANE; GONÇALVES, VITOR; CABRERA-PASCA, GABRIEL; SAXENA, RAJENDRA N.; CARBONARI, ARTUR W.
In this work we tested the methodology to map magnetic hyperfine interactions in strongly correlated materials using a free open-source all-electron FP-LAPW code ELK. The RECd (RE = Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) series was chosen as a laboratory system, since an almost complete set of experimental data on the hyperfine parameters at Cd sites in these compounds was acquired previously with an extremely sensitive TDPAC technique [1]. Moreover, these TDPAC results were complemented with WIEN2k DFT calculations that allow a qualitative comparison of the two codes. The ELK calculations were performed with PBE96 GGA-type exchange-correlation functional, the cases of scalar relativistic approximation and fully relativistic relaxation of the states were treated separately. A dense k-mesh and adequate R(MT)K(max) were chosen in both cases to comply with the sensitivity of magnetic hyperfine parameters. We emphasize that the exploited version of ELK accounted for the contact field only. Yet, as it is the only contribution expected for Cd site in RECd, the values of B(hf), albeit generally overestimated, have shown reasonable agreement with the experiment (Fig. 1). Spin-orbit coupling taken into account led to a decrease in deviation from experimental data. An addition of the Hubbard-like term was essential to reach a tolerable result for CeCd. This behavior may be associated with a weaker localization of the 4f electron of Ce. Concerning the potential sources of discrepancy between our ELK results and those previously obtained with WIEN2k, (i) a different way of accounting for relativistic corrections, (ii) the use of GGA (our ELK study) versus LDA (previous WIEN2k study) and other details are discussed.
Synthesis and characterization of Fe3O4-HfO2 nanoparticles by magnetization and hyperfine interactions measurements
2020 - MATOS, IZABELA T.; SALES, TATIANE S.; CABRERA-PASCA, GABRIEL; BURIMOVA, ANASTASIA; SAXENA, RAJENDRA N.; PEREIRA, LUCIANO F.; OTUBO, LARISSA; CARBONARI, ARTUR W.
Nanoparticles (NPs) that combine biocompatibility and enhanced physical characteristics for biomedical applications are currently an area of intense scientific research. Hafnium oxide NPs is an innovative approach in the anticancer treatment by radiotherapy due to their low toxicity and enhancement of local dose in the tumor reducing the total radiation dose for the patient [1]. The combination of this amazing property with the excellent magnetic hyperthermia performance of Fe3O4 NPs can produce a promising nanomaterial for cancer therapy. In the present work, we have synthesized NPs samples of Fe3O4 doped with 10%Hf and HfO2 doped with 10% Fe by chemical procedures. The samples had their morphological, structural, and magnetic properties characterized by some results being displayed in Fig. 1. The crystal structure of the samples was characterized by X-ray Diffraction (XRD), whose results present a single phase. Transmission Electron Microscopy (TEM) images show spherical and hexagonal NPs with an average size of 12 nm as displayed in Fig. 2. The magnetic property was investigated by magnetization measurement. The results from the temperature dependence of ZFC-FC magnetization show a large peak in the ZFC curve corresponding to a broad distribution of blocking temperatures as shown in Fig. 1(b). Fortunately, when irradiated with neutrons in a research reactor, the nuclear reaction 180Hf(n,γ)181Hf yields the probe nucleus 181Hf(181Ta) used by the perturbed angular correlations (PAC) technique to measure hyperfine interactions. Both samples show electric quadrupole interaction characteristics of the HfO2 phase indicating that the Fe replaces Hf in HfO2 NPs, but rather than substituting Fe, Hf form HfO2 NPs diluted in Fe3O4 NPs. Moreover, a pure time-dependent magnetic dipole interaction below 300 K was observed for Fe3O4 NPs mixed with 10% of HfO2.
Annealing effect on the structural and local magnetic properties of nickel ferrite nanoparticles studied by hyperfine interaction measurements
2020 - RODRIGUES, PRISCILA S.; MATOS, IZABELA T.; SALES, TATIANE S.; BURIMOVA, ANASTASIA; CABRERA-PASCA, GABRIEL; PEREIRA, LUCIANO F.; SAXENA, RAJENDRA N.; OTUBO, LARISSA; CARBONARI, ARTUR W.
Nickel ferrite in the form of nanoparticles is a technologically important material that can be applied for the production of biosensors, catalysts, drug delivery, and magnetic resonance contrast agents. In this work NiFe O samples comprising spherical nanoparticles of ~6 nm in diameter have been synthesized via a thermal decomposition route. The quality control of the samples was carried out with conventional techniques including X-ray diffraction and transmission electron microscopy. Post-synthesis XRD pattern revealed textured spinel NiFe O . Local magnetic properties were examined with Time Differential Perturbed Angular Correlation (TDPAC) spectroscopy within the 12 - 773K temperature range with In( Cd) probe introduced into the samples at synthesis. Quasi-static magnetic properties were observed (including above room temperature), as expected due to the small time window of TDPAC. The TDPAC results shown in Fig. 1 were analyzed using a model with combined electric quadrupole and magnetic dipole interactions. An expressive dynamic interaction was observed upon heating after synthesis. A theoretical model based on the Brillouin function for different ionic moments was applied to study the evolution of the hyperfine magnetic field with temperature (see Fig. 1-2) and allowed to attribute the magnetic interaction to the probe location at Fe3+ site. Site occupancy and the interplay between magnetic and structural properties are discussed with respect to application perspectives.
Local inspection of magnetic properties in GdMnIn by measuring hyperfine interactions
2020 - CABRERA-PASCA, G.A.; MAGNO, J.F.; FERREIRA, W.L.; CAMPOS, A.C.; BOSCH-SANTOS, B.; SALES, T.S.N.; PEREIRA, L.F.D.; BURIMOVA, A.; SAXENA, R.N.; FREITAS, R.S.; CARBONARI, A.W.
GdMn2 is a member of a series of Laves phase containing a rare-earth element and a magnetic 3dtransition metal with very peculiar magnetic properties[1]. Doping with a non-magnetic element such as indium affects these properties[2,3]. GdMnIn is reported to crystalize in the hexagonal MgNi2-type structure presenting a spin-glass behavior with no magnetic order attributed to the triangular spin frustration of magnetic ions[3]. The observed absence of long-range interactions by magnetization measurements along with the almost impossible measurements with neutron diffraction due to the presence of Gd with very high neutron absorption cross section makes the investigation of local exchange interactions in this compound very difficult. In the present work, measurements of hyperfine interactions at In sites using 111In(111Cd) probe nuclei were carried out by perturbed angular correlations (PAC) technique to investigate the local magnetic exchange in GdMnIn compound. Results displayed in Fig. 1 for the behavior of the major component (Vzz) of the electric field gradient (efg) tensor and the distribution of electric quadrupole frequency () show a strong instability of the electronic environment of In sites when temperature decreases indicating a Mn-In disorder. The weak magnetic hyperfine field at In sites also shown in Fig.1 with an anomalous temperature dependence below around 140 K along with the increase in the angle between Bhf and Vzz directions suggest a weak long-range exchange interaction.
Cd impurities in Vanadium oxides
2021 - BURIMOVA, ANASTASIA; LEITE NETO, OSMAR F.; BOSCH-SANTOS, BRIANNA; CORREA, EDUARDO L.; PEREIRA, LUCIANO F.D.; SALES, TATIANE S.N.; RIBEIRO JUNIOR, IBERE S.; COSTA, MESSIAS S.; COSTA, CLEIDILANE; DANG, THANH T.; ZYABKIN, DMITRY; VAN STIPHOUT, KOEN K.F.; GERAMI, ADELEH M.; CORREIA, JOAO M.; SCHELL, JULIANA; CARBONARI, ARTUR W.
The number of metastable phases, the capriciousness at changing external conditions, and lack of accurate description of local behavior already resulted in severe misinterpretation of experimental outcomes for vanadium oxides[1–3]. The scope of already implemented and potential applications of vanadium oxides is, indeed, impressive, particularly as a battery cathode for energy storage[ 4]. Doping is widely exploited as a means of application-oriented tuning of the material properties. The properties of each particular phase may be tuned by doping to satisfy specific requirements and/or improve the functional performance. In the work here reported, electric quadrupole interaction on 111mCd nuclei implanted in vanadium pentaoxide doped with different concentrations of Cd were measured with time-differential perturbed angular correlations (TDPAC). Pure V2O5 as well as doped with 1%, 5%, and 10% of Cd were measured at different temperatures. To correlate the results with the possible formation of different phases and compounds, samples of VO2, CdV2O6, and Cd2V2O7 were also measured. The intention is to provide a comprehensive description, at an atomic level, of the doping effects on the local crystal structure and the electronic structure around the impurity and the consequences on the properties of the host oxides. Preliminary results show that the probability of formation of cadmium vanadates is low but the temperature and atmosphere of measurements have an important effect on the local scale.

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