KATIUSSE SOARES DE SOUZA

KATIUSSE SOARES DE SOUZA

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Mapeamento da reação de síntese de nanopartículas de óxido de molibdênio a partir do precursor de acetato de molibdênio (II)
2024 - SOUZA, KATIUSSE S. de
Nesta dissertação, conduz-se um estudo sistemático sobre a utilização do acetato de molibdênio (II) como precursor organometálico na síntese de nanoestruturas e óxidos de molibdênio por meio de decomposição térmica, com uma análise aprofundada dos efeitos da temperatura sobre a formação dessas nanoestruturas. O trabalho envolve a preparação de amostras radioativas (com 111In(111Cd)) e não radioativas, caracterizadas por meio de técnicas convencionais de análise de materiais, como difração de raios X (DRX), microscopia eletrônica de varredura (MEV), espectroscopia no infravermelho por transformada de Fourier (FTIR) e análises térmicas (TGA e DTG), além da análise estrutural local pela técnica de correlação angular perturbada gama-gama (TDPAC). Os resultados demonstram que o método de decomposição térmica permite a obtenção de um material complexo à base de molibdênio, que, ao ser submetido a tratamentos térmicos, promove a cristalização de trióxido de molibdênio(α-MoO3) com morfologia de microfitas e a formação de nanopartículas de dióxido de molibdênio (MoO2) com estrutura monoclínica. As análises por TDPAC corroboram a presença da fase α-MoO3 sob determinadas condições experimentais, além de revelarem sítios cristalinos atribuíveis ao MoO3 com observação de transição de MoO2 para Mo em determinadas condições térmicas. Esta investigação fornece contribuições relevantes para a compreensão dos efeitos térmicos nos óxidos de molibdênio, evidenciando o potencial do acetato de molibdênio como um precursor organometálico eficaz na síntese de nanoestruturas.
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.
Development of flexible magnetic films by the incorporation of Ni/Ni3C nanoparticles in a matrix of Amazonian tannic extract (Myrcia atramentifera)
2024 - SILVA, CRYSTIAN W.C. da; SOUZA, KATIUSSE S. de; SILVA, BARBARA P.G.; FREITAS, RAFAEL S. de; LAZAR, DOLORES R.R.; PASCA, GABRIEL A.C.; CARBONARI, ARTUR W.; OTUBO, LARISSA
The development of nanostructured magnetic materials based on Ni and its compounds (Ni/Ni3C) has been the objective of scientific research due to the versatility of applications that these materials. In this context, magnetic films can be applied in a variety of technologies such as data storage, flexible spintronics, chemical detection, and magnetic sensors.[1] Additionally, the growing prospect of obtaining environmentally eco-friendly materials has promoted the use of vegetable matrices for film synthesis, such as tannins, for example. In this work, we report the fabrication of flexible magnetic films on paper substrates by adding Ni/Ni3C nanoparticles to the tannin extract matrix of the Amazonian species Myrcea atramentífera.[2] The tannin extract solution was obtained by processing the species' bark through grinding, sieving, and water extraction for 8 hours at 70°C, followed by filtration and concentration. After this step, a tannin extract suspension containing 0.1% Ni/Ni3C was prepared by dispersion in an ultrasonic processor. The suspension was dispersed onto a paper substrate and dried at 30 °C for 10 minutes. The films were characterized by XRD, SEM, AFM, and TGA/DSC measurements. The structural and morphological results indicate the formation of continuous films with dispersed nanoparticles. Thermal analysis results suggest that the nanoparticles dispersed in the films maintain structural stability up to 350 °C. The films present macroscopic magnetic response at room temperature, which can be attributed to the presence of nanoparticles with a coercive field of 100 Oe and saturation magnetization of 26 emu/g. [3]
Synthesis and local characterization of CoO nanoparticles in distinct phases
2024 - SANTOS, SUZILENE V.; COSTA, CLEIDILANE S.; PARAGUASSU, WALDECI; SILVA, CRYSTIAN W.C.; OTUBO, LARISSA; SOUZA, KATIUSSE S.; CORREA, BRUNO S.; MIRANDA-FILHO, ARNALDO A.; FERREIRA, WANDERSON L.; CARBONARI, ARTUR W.; CABRERA-PASCA, GABRIEL A.
The advancement of functional nanomaterials has become a major focus of recent research, driven by the exceptional properties these materials display compared to their macroscopic (bulk) counterparts. Cobalt oxide nanoparticles (CoO-NPs) stand out primarily for their catalytic and magnetic properties, which can enable a range of technological applications, such as advanced catalysts, drug delivery systems, implants, prosthetics, sensors. However, in addition to the dependence on factors such as size, morphology, and functionalization, the properties of CoO-NPs are significantly influenced by the crystal structure. Therefore, local investigation into the polymorphic structures of CoO at the nanometric scale may provide new insights into the local structural and magnetic characteristics of these systems. In this report, we address the synthesis and local characterization of cobalt oxide (CoO) nanoparticles in the rock-salt cubic fcc-CoO and Wurtzite hpc-CoO phases, obtained through thermal decomposition. We analyze the influence of oleylamine and oleic acid ligands on the structural and morphological control of these systems. The obtained nanoparticles were characterized using conventional techniques such as X-ray diffraction (XRD), transmission electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. Local characterization was carried out by the perturbed angular correlation (PAC) nuclear technique using the radioactive tracer 111In(111Cd). Measurements were conducted at 295 and 10 K to investigate possible magnetic phase transitions in these systems. XRD results confirmed the formation of fcc-CoO and hcp-CoO phases. The phase fcc was obtained with the pair of oleylamine and oleic acid ligands, while the phase hcp phase was synthesized using only oleylamine. Additionally, nanoparticles synthesized with oleylamine and oleic acid exhibited better morphological control compared to those produced with only oleylamine. Raman spectroscopy analyses suggest a phase transformation process resulting in Co3O4. PAC results for hyperfine interactions at the 111In(111Cd) probe nucleus, indicate that the hcp-CoO phase shows smaller hyperfine magnetic interactions (Bhf = 1 T) compared to the fcc-CoO phase (Bhf = 17 T). This suggests the mechanism of superexchange interactions, which are strongly influenced by the Co-O-Co bond angle, which is 110° for the hpc-CoO phase and 180° for the fcc-CoO phase due to the geometries of the systems.
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.
Investigation of Ni/Ni3C nanoparticle synthesis for application as a catalyst in carbon nanostructure growth
2023 - SILVA, CRYSTIAN W.C.; CABRERA-PASCA, GABRIEL A.; SOUZA, KATIUSSE S.; COSTA, CLEIDILANE S.; COSTA, MESSIAS S.; CORREA, BRUNA S.; FERREIRA, WANDERSON L.; FREITAS, RAFAEL S.; CARBONARI, ARTUR W.; OTUBO, LARISSA
The synthesis of functional Ni/Ni3C nanoparticles has attracted significant interest, especially in the field of electrocatalysis, where these promising nanoparticles are employed to develop sophisticated electrocatalysts, particularly for hydrogen production through the hydrogen evolution reaction. However, the significant reactivity of these systems makes them susceptible to degradation, compromising their catalyst performance. One solution explored to mitigate this problem involves the catalytic growth of carbon nanostructures to encapsulate and protect these nanoparticles. The mechanisms for the formation of carbon nanostructures from nanoparticles remain the subject of this study. Among the reported processes, the annealing of nanocatalysts has been described as a highly effective method for producing such systems. This process is influenced by parameters, such as the temperature, atmosphere, and structural and morphological characteristics of the nanocatalysts. In the work reported here, we evaluated the influence of different ligand pairs (oleylamine/oleic acid and oleylamine/palm kernel oil) on the structural, morphological, and magnetic properties of Ni/Ni3C nanoparticles obtained through thermal decomposition at 240 °C for 3 h. Additionally, we investigated the impact of annealing in a nitrogen atmosphere on the structural properties of these nanoparticles and the growth of carbon nanostructures as a protective mechanism. The analyses include conventional techniques such as X-ray diffraction, transmission electron microscopy (TEM), magnetization measurements, and thermogravimetric analysis with differential scanning calorimetry. Additionally, local analysis was conducted using perturbed angular correlation spectroscopy (PAC) across a broad temperature range (30–693 K), utilizing the radioactive tracer 111In(111Cd) for these measurements. The characterizations revealed that palm kernel oil contributes to the formation of nanoparticles with a higher Ni3C content, a broader size distribution, and a lower saturation magnetization. The PAC measurements in the range of 30–50 K, along with density functional theory calculations, indicated the absence of the Ni-hcp phase in the nanoparticles, a topic frequently discussed in the literature. Moreover, the presence of Ni3C regions with carbon deficiency was identified, characterized by a quadrupole frequency (νQ) of 23 MHz and a hyperfine field (Bhf) of 1 T. The temperature-dependent local analysis, combined with thermal analysis and TEM measurements, confirmed the development of carbon nano-onions around the nanoparticles during thermal treatment above 695 K in a nitrogen atmosphere. This observation demonstrates that nanoparticles obtained with palm kernel oil, which has the highest Ni3C content, offer superior encapsulation of Ni nuclei through these graphitic nanostructures.
Comparative local analysis of Ni/Ni3C nanoparticles synthed with oleylamine/oleic acid and oleylamine/palm kernel oil ligand pairs
2023 - SILVA, CRYSTIAN W.C. da; OTUBO, LARISSA; SOUZA, KATIUSSE S. de; CARBONARI, ARTUR W.; CORREA, BRUNO S.; FREITAS, RAFAEL S. de; PASCA, GABRIEL A.; COSTA, CLEIDILANE S.
In recent decades, Ni/Ni3C nanoparticles have been a topic of interest, especially for their catalytic and magnetic properties, promising as electrocatalysis, for example [1]. These systems are usually obtained by chemical methods, in the presence of ligands responsible for controlling their structure and morphology [2]. In this work, we carried out a comparative study of the hyperfine interactions occurring in Ni/Ni3C nanoparticles, synthed by thermal decomposition in the presence of oleylamine/oleic acid and oleylamine/palm kernel oil ligand pairs, at 513 K, for 3 hours. The local analysis was performed using perturbed correlation spectroscopy (PAC) in the temperature range from 30K to 300K, using the 111Cd probe, implanted in the samples by diffusion, during the synthesis. The parameters of the hyperfine interactions were compared to the results obtained by XRD, TEM and magnetization, indicating the obtainment of Ni/Ni3c nanoparticles of the core-shell type, showing a higher Ni3C content, greater distribution and lower saturation magnetization for nanoparticles synthed with palm kernel oil compared to those obtained with oleic acid. In addition, the hyperfine parameters showed the existence of regions with a quadrupole frequency of 24 MHz and a magnetic hyperfine field of 1T in both samples, which may be indicative of carbon-deficient Ni3C regions, predicted in the literature [3].