Papers by Everton Bonturim
Dalton Transactions
Production of translucent and flexible films featuring blue persistent luminescence. The films sh... more Production of translucent and flexible films featuring blue persistent luminescence. The films show great transmittance at visible range and can persist for up to 90 min after charging with UV light.
Radiation Physics and Chemistry
Nanotechnology, 2021
Resistive switching (RS) devices are promising forms of non-volatile memory. However, one of the ... more Resistive switching (RS) devices are promising forms of non-volatile memory. However, one of the biggest challenges for RS memory applications is the device-to-device (D2D) variability, which is related to the intrinsic stochastic formation and configuration of oxygen vacancy (VO) conductive filaments (CFs). In order to reduce the D2D variability, control over the formation and configuration of oxygen vacancies is paramount. In this study, we report on the Zr doping of TaO x -based RS devices prepared by pulsed-laser deposition as an efficient means of reducing the VO formation energy and increasing the confinement of CFs, thus reducing D2D variability. Our findings were supported by XPS, spectroscopic ellipsometry and electronic transport analysis. Zr-doped films showed increased VO concentration and more localized VOs, due to the interaction with Zr. DC and pulse mode electrical characterization showed that the D2D variability was decreased by a factor of seven, the resistance win...
Nanomaterials are used in many areas of biological research. Nanoparticles can be used as active ... more Nanomaterials are used in many areas of biological research. Nanoparticles can be used as active components in various functional materials and devices of interest for bio-applications. Nanoparticles have long been signaled as a potential revolution in the way we probe and interact with biological materials and organisms. This is because they are small enough to interact with their environment at a molecular level, but strong enough to maintain useful properties such as luminescence over extended periods. However, the physical properties of the host materials with nanometer dimensions may differ markedly from those of their bulk counterparts due to the particle size-dependent influences such as structure disordering and surface defects. The development of materials incorporated in the silica has been studied since these materials exhibit intrinsic luminescent properties of the inorganic part and characteristics of the silica matrix. In the present work Nd2(MoO4)3 compounds incorporated into silica particles were prepared using a microwave synthesis procedure. Then, the material was dispersed in ethyl alcohol and functionalized with APTES: 3-aminopropyltriethoxisilane. The emission spectra show broad bands when compared with the emission spectra of the own rare earth compound. The narrow lines are assigned to 4f–4f transitions from the emitting 4 F3/2 level to the 4 I9/2 and, 4 I11/2 levels, centered around 915 and 1060 respectively. Emission spectrum of the Nd2(MoO4)3 @ Si dispersion showed an enlargement of the bands. It is also observed the broadened peak of the 4 F3/2 → 4 I9/2, 4 I11/2 transitions in the luminescent amino-functionalized silica particles as compared with the core compound spectrum. These materials were conjugated to anti-IgG antibody and presented high efficient performance in detect human antigen. They can concluded that particles are potential candidates for development of the bioassays acting as a biomarker.
Materials containing rare earth metals are receiving increasing attention due to its wide range o... more Materials containing rare earth metals are receiving increasing attention due to its wide range of potential applications, including bioanalytical, images, dye-sensitized solar cells, nanobiotechnology, catalyses among others. The distinguished spectroscopic properties of lanthanides (intense emission bands, high color purity, long lifetime and high quantum efficiency) make them strong candidates for use as markers or bio- selective detectors. Besides the interest in developing nanoparticles ( NP ) associated with biological materials continues growing rapidly . This interest is mainly motivated by the desire to simultaneously exploit the properties of both the NP and biological components in new hybrid operating devices or materials that can be applied in strategic areas. In this work, we design various materials, synthesized and characterized in several laboratories that are part of the group fluoroimunoensaios inct - INAMI and NanoBio network and that have potential to use as biological markers .An attention to materials that emit in the regions of Vis and IR as the compound of Eu and Nd compounds, RE3 + compounds covered with silica and functionalized, RE3 + complexes dispersed in polymeric matrix and have sharp, etc. luminescence will be discussed. Also it will show these nanoparticles in - action , signaling biological materials at very low concentrations , on the order of nanomolar . The principal studies are connected to the diagnostic field and has been studied mainly Leishmania , PSA , LDL, sickle cell disease, estradiol and Chagas disease.
Nature Communications, 2019
Deterministic creation of multiple ferroelectric states with intermediate values of polarization ... more Deterministic creation of multiple ferroelectric states with intermediate values of polarization remains challenging due to the inherent bi-stability of ferroelectric switching. Here we show the ability to select any desired intermediate polarization value via control of the switching pathway in (111)-oriented PbZr0.2Ti0.8O3 films. Such switching phenomena are driven by kinetic control of the volume fraction of two geometrically different domain structures which are generated by two distinct switching pathways: one direct, bipolar-like switching and another multi-step switching process with the formation of a thermodynamically-stable intermediate twinning structure. Such control of switching pathways is enabled by the competition between elastic and electrostatic energies which favors different types of ferroelastic switching that can occur. Overall, our work demonstrates an alternative approach that transcends the inherent bi-stability of ferroelectrics to create non-volatile, dete...
Journal of Alloys and Compounds, 2018
The synthesis of efficient nanosized persistent luminescence materials remains a challenge for th... more The synthesis of efficient nanosized persistent luminescence materials remains a challenge for the community. Paradoxically, due to the dependence of the point lattice defects and the persistent luminescence efficiency, the control of the defect formation, favorable when the materials are prepared at high temperatures, normally leads to particle growth and sintering. In this work, efficient nanosized rare earth doped disilicates Sr 2 MgSi 2 O 7 :Eu 2þ ,Dy 3þ were synthesized via three different wet-chemical methods taking advantages of the microwave-assisted reduction process as a support step to produce high-quality polycrystalline materials. The crystallite size of the sample showed to be smaller when the decomposition temperature of the precursors is higher and close to the phase formation energy. The excitation VUV spectroscopy indicated that despite being nanocrystalline, the materials optical band gap has just a small difference compared one to another. The reduction of Eu 3þ to Eu 2þ was successfully obtained, since the f-d interconfigurational transitions of Eu 2þ 4f 6 5d 1 /4f 7 emission were observed in the blue region of the spectra. The persistent luminescence efficiency measured through its lasting decay time was close to the commercial materials references and with the advantage of having size control during the synthesis method that can lead to the size dependent applications of photonic materials.
Cerâmica, 2013
Ba0,50Sr0,50Co0,80Fe0,20O3-d (BSCF) apresenta propriedades físicas, químicas e microestruturais a... more Ba0,50Sr0,50Co0,80Fe0,20O3-d (BSCF) apresenta propriedades físicas, químicas e microestruturais adequadas para compor o cátodo de uma célula a combustível de óxido sólido de temperatura intermediária (ITSOFC). Este trabalho tem por objetivo a síntese e a caracterização do BSCF obtido pelo método dos citrados-EDTA. Os resultados obtidos por difração de raios X (DRX) indicaram fases secundárias para o material calcinado a 700 e 800 ºC e fase única com estrutura cristalina do tipo perovskita para 900 ºC. As micrografias obtidas por microscopia eletrônica de varredura dos particulados evidenciou a formação de aglomerados de tamanho < 20 µm. A análise dilatométrica dos compactos indicou a temperatura de sinterabilidade ~ 1050 ºC. Os resultados de DRX das cerâmicas sinterizadas evidenciaram a presença de fase única perovskita. As micrografias dos sinterizados confirmaram a formação de maior porosidade nas amostras sinterizadas a 1000 °C /1 h, conformadas com pó calcinado a 900 °C.
Meus mais sinceros agradecimentos aos profissionais que contribuíram direta ou indiretamente para... more Meus mais sinceros agradecimentos aos profissionais que contribuíram direta ou indiretamente para a realização deste trabalho. Muitas vezes a ajuda não vem das respostas e sim dos questionamentos feitos frente a um problema. À Dra. Emília Satoshi Miyamaru Seo pela orientação neste trabalho, aos seus ensinamentos pessoais, acadêmicos e profissionais, desde a minha Iniciação Científica.
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Papers by Everton Bonturim