Artur W Carbonari | Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP) (original) (raw)

Papers by Artur W Carbonari

Research paper thumbnail of Temperature dependence of the magnetic hyperfine field at cerium impurity in Co

Hyperfine Interactions, Apr 1, 2007

Perturbed gamma-gamma angular correlation (PAC) technique was used to measure the magnetic hyperf... more Perturbed gamma-gamma angular correlation (PAC) technique was used to measure the magnetic hyperfine field (Bhf) at Ce impurity in Co using 140La→ 140Ce probe. The radioactive 140La produced by neutron irradiation of lanthanum metal with thermal neutrons was introduced in Co by arc melting in argon atmosphere. The present measurements cover the temperature range from 4.2– 1300 K. Two pure magnetic interactions were observed at impurity sites, corresponding to a ferromagnetic ordering of Co moments in hcp and fcc phases. The temperature dependence of Bhf for both phases, however, shows a sharp deviation from an expected standard Brillouin-like behavior for the host magnetization. The results are discussed in terms of a simple molecular-field model where the localized moment at impurity ions as well as the conduction electron contributions to the hyperfine field are taken into account.

Research paper thumbnail of Cd implantation in α−MoO3 : An atomic scale study

Physical Review Materials

Research paper thumbnail of Electric Field Gradient at Nb Site in the Intermetallic Compounds Nb3X (X = AI, In, Si, Ge, Sn) Measured by PAC

Zeitschrift für Naturforschung A

The electric field gradient (efg) at the Nb site in the intermetallic compounds Nb3X (X = Al, In,... more The electric field gradient (efg) at the Nb site in the intermetallic compounds Nb3X (X = Al, In, Si, Ge, Sn) was measured by the Perturbed Angular Correlation (PAC) method using the well-known gamma-gamma cascade of 133 -482 keV in 181Ta from the β- decay of 181Hf, substituting approximately 0.1 atom percent of Nb. The PAC results show that Vzz drops by nearly 40% when X changes from Al to In, and by about 25% when X changes from Si to Ge and Sn. This behavior is most probably related to the change in the degree of sp hybridization in these compounds. The Vzz values of the studied compounds do not follow the well known universal correlation for the efg's in non-cubic metals but the observed trend is well reproduced by results of ab-initio electronic structure calculations. In the case of Nb3 Al a linear temperature dependence of the quadrupole frequencies was observed in the temperature range of 6.5 to 1210 K.

Research paper thumbnail of Magnetic phase diagram of the solid solution LaMn2(Ge1−xSix)2 (0 ≤ x ≤ 1) unraveled by powder neutron diffraction

Scientific Reports

The structural and magnetic properties of the ThCr2Si2-type solid solution LaMn2(Ge1−xSix)2 (x = ... more The structural and magnetic properties of the ThCr2Si2-type solid solution LaMn2(Ge1−xSix)2 (x = 0.0 to 1.0) have been investigated employing a combination of X-ray diffraction, magnetization and neutron diffraction measurements, which allowed establishing a magnetic composition-temperature phase diagram. Substitution of Ge by Si leads to a compression of the unit cell, which affects the magnetic exchange interactions. In particular, the magnetic structure of LaMn2(Ge1−xSix)2 is strongly affected by the unit cell parameter c, which is related to the distance between adjacent Mn layers. Commensurate antiferromagnetic layers and a canted ferromagnetic structure dominate the Si-rich part of the solid solution, whilst an incommensurate antiferromagnetic flat spiral and a conical magnetic structure are observed in the Si-poor part.

Research paper thumbnail of The peculiarities of reduction and doping of vanadium oxides probed by TDPAC spectroscopy at ISOLDE

Research paper thumbnail of International Workshop on Utilization of Research Reactors, São Paulo, Brazil

Research paper thumbnail of Investigation of local magnetic properties of CeCd as a function of the unit cell volume by means of first principles calculations

Research paper thumbnail of Investigation of doping influence on local structure and phase transitions in vanadium oxides by time-differential perturbed angular correlations at ISOLDE-CERN

1 Instituto de Pesquisas Energéticas e Nucleares, IPEN, São Paulo, Brazil 2 Universidade Federal ... more 1 Instituto de Pesquisas Energéticas e Nucleares, IPEN, São Paulo, Brazil 2 Universidade Federal do Pará, Campus de Abaetetuba, Pará, Brazil 3 Instituto de Física da Universidade de São Paulo (IFUSP), São Paulo, SP, Brazil 4 Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina 5 EP Department, ISOLDE-CERN, CH-1211 Geneva 23, Switzerland 6 Institute for Materials Science and Center for Nanointegration, Duisburg-Essen (CENIDE), University of Duisburg-Essen, 45141 Essen, Germany 7 Centro de Ciências e Tecnologias Nucleares (CCTN), Instituto Superior Técnico, Universidade de Lisboa, Portugal 8 Chair of Department of Materials for Electronics, Technische Universität Ilmenau, Institute of Materials Science and Engineering, Gustav-Kirchhoff-Straße 5, 98693 Ilmenau, Germany

Research paper thumbnail of Investigation of hyperfine interactions in immunoglobulin G with perturbed angular correlation spectroscopy using 111Cd

Research paper thumbnail of O IPEN e a saúde

Research paper thumbnail of Huge negative magnetic hyperfine fields for 111Cd probe nuclei in the Fe3X (X=C, Ge, and Ga) compounds with specific properties

Research paper thumbnail of Effects of surfactant on the morphology of α-Bi2O3 synthesized by the Sol-gel method

Nano and micromaterial research, with a well-defined size and shape, has attracted attention from... more Nano and micromaterial research, with a well-defined size and shape, has attracted attention from researchers in the areas of chemistry, physics, engineering and biomedicine, due to the wide range of possible applications such as: health, environment, catalysis and miniaturization of electronic devices. In this sense, the chemical routes of synthesis, such as Sol-Gel, are more prominent because it allows the production of particulate materials and thin films, with controllable size and morphology. In this work, bismuth oxide microparticles were synthesized by the Sol-Gel method using metallic bismuth (99.999% purity) in acid solution. Initially, bismuth was diluted with nitric acid solution and distilled water. After dilution, citric acid (600 mg) and ethylene glycol were added. The volume of ethylene glycol was varied from 1 to 3.75 mL, in order to study the morphological effects of its concentration. The samples were then subjected to the calcination process at 673 K for 12 hours....

Research paper thumbnail of Insights into anomalous magnetic hyperfine field at Ce impurity in LaMn2X2 (X=Si, Ge)

Research paper thumbnail of Effects of an external magnetic field on the hyperfine parameters in RE2O3 (RE = Gd, Er) nanoparticles measured by perturbed angular correlation spectroscopy

AIP Advances, 2020

In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Pertu... more In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Perturbed Angular Correlation (PAC) spectroscopy, a local technique, plus external magnetic field, was used to elucidate local interactions and possible mapping of the different contribution in these compounds. NPs were synthesized by thermal decomposition and characterized by transmission electron microscopy and X-ray diffraction. PAC measurements were performed using 111In(111Cd) as probe nuclei, with and without the application of an external magnetic field (EMF) of 0.5 T in different temperatures (50 K, 100 K, 200 K, 300 K). Results show that the hyperfine magnetic field is almost zero when the probe is located at the symmetric site, and ∼4 T and ∼5 T for Gd2O3 and Er2O3, respectively, when the probe occupies the asymmetric field.

Research paper thumbnail of Effect of the magnetic impurity on the charge diffusion in highly dilute Ce doped LaMnO3

AIP Advances, 2020

LaMnO3+δ is a complex oxide, which, depending on the oxygen excess concentration, presents differ... more LaMnO3+δ is a complex oxide, which, depending on the oxygen excess concentration, presents different crystalline structure and interesting magnetic and electric properties such as colossal magnetoresistance, polaron dynamics, multiferroic behavior, and charge-orbital ordering. This complexity requires different characterization techniques to draw a picture as complete as possible allowing a good understanding of these phenomena. Here, we have used the perturbed angular correlation (PAC) technique to measure hyperfine interactions at La and Mn sites of LaMnO3+δ(δ ∼0.15) using 140Ce and 111Cd at La sites as probe nuclei in order to investigate within an atomic scale the magnetic and electric interactions in this compound. The results show that 111Cd nuclei occupy highly symmetric local sites in agreement with a rhombohedral structure. The magnetic hyperfine field (Bhf) measured with 111Cd at La sites is very small (Bhf = 0.40 T) due to the supertransferred magnetic field from Mn neigh...

Research paper thumbnail of Cd and In-doping in thin film SnO2

Journal of Applied Physics, 2017

In this paper, we investigate the effects of doping in the local structure of SnO2 by measuring t... more In this paper, we investigate the effects of doping in the local structure of SnO2 by measuring the hyperfine interactions at impurity nuclei using the Time Differential Perturbed Gamma-Gamma Angular Correlation (TDPAC) method in addition to density functional theory simulations. The hyperfine field parameters have been probed as a function of the temperature in thin film samples. The experimental results reveal that 117Cd/In and 111In/Cd are incorporated and stabilized in the SnO2 lattice replacing the cationic site. Significant differences in the electric field gradient were observed from TDPAC measurements with both the probe nuclei. Furthermore, the absence of strongly damped spectra further indicates that implanted Cd atoms (for 117Cd/In probe nuclei measurements) easily occupy regular substitutional Sn sites with good stability. The simulated value for the electric field gradient obtained with the first oxygen neighbor removed is closer to the experimental value observed for 1...

Research paper thumbnail of In and Cd as defect traps in titanium dioxide

Hyperfine Interactions, 2016

We present a study of TiO 2 single crystals from the point of view of the dopant atom that simult... more We present a study of TiO 2 single crystals from the point of view of the dopant atom that simultaneously behaves as the probing element. We used gamma-gamma time dependent perturbed angular correlations working with selected tracer elements (111 In/ 111 Cd, 111m Cd/ 111 Cd) together to investigate the different behavior of Cd and In dopants, particularly their interaction with point defects in the TiO 2 lattice. Results show that the hyperfine interactions observed at 111 Cd from 111 In or 111m Cd decay are quite different. 111 In/ 111 Cd results show a single site fraction characterized by a quadrupole frequency with asymmetry parameter similar to those observed for the same probe nuclei in bulk TiO 2 oxides. Results for 111m Cd/ 111 Cd reveal two site fractions, one characterized by the same hyperfine parameters to those measured in bulk TiO 2 and another fraction characterized by a quadrupole frequency and asymmetry parameters with higher values, as observed in thin This article is part of the Topical Collection on

Research paper thumbnail of Magnetic and transport properties assisted by local distortions in Bi 2 Mn 4 O 10 and Bi 2 Fe 4 O 9 multiferroic compounds

Journal of Alloys and Compounds, 2015

We have performed a comprehensive study on the magnetic and electrical properties through macrosc... more We have performed a comprehensive study on the magnetic and electrical properties through macroscopic and local characterizations on Bi 2 Mn 4 O 10 and Bi 2 Fe 4 O 9. An analysis of the temperature evolution of local distortions, which was obtained by perturbed angular correlation measurements, revealed an anomalous behavior of the quadrupolar frequency and asymmetry parameter below the antiferromagnetic ordering temperature for both samples. The combined results suggest correlations between magnetic, electric, and elastic interactions. At high temperature, we have observed that the hopping frequency and activation energy in the electrical transport mechanism are close related to hyperfine parameters, electrical field gradient and asymmetry parameter, due to modifications in the equilibrium positions of oxygen atoms conforming octahedral, pyramidal, and tetrahedral environments. Anharmonic lattice effects are much more pronounced in a temperature range close to room temperature.

Research paper thumbnail of Local investigation with radioactive probe of wide band gap oxides thin films doped with transition metals

Local investigation with radioactive probe of wide band gap oxides thin films doped with transiti... more Local investigation with radioactive probe of wide band gap oxides thin films doped with transition metals.

Research paper thumbnail of Investigation of Rare Earth (RE = La, Dy, and Er) doping of HfO2 by perturbed angular correlation spectroscopy

Research paper thumbnail of Temperature dependence of the magnetic hyperfine field at cerium impurity in Co

Hyperfine Interactions, Apr 1, 2007

Perturbed gamma-gamma angular correlation (PAC) technique was used to measure the magnetic hyperf... more Perturbed gamma-gamma angular correlation (PAC) technique was used to measure the magnetic hyperfine field (Bhf) at Ce impurity in Co using 140La→ 140Ce probe. The radioactive 140La produced by neutron irradiation of lanthanum metal with thermal neutrons was introduced in Co by arc melting in argon atmosphere. The present measurements cover the temperature range from 4.2– 1300 K. Two pure magnetic interactions were observed at impurity sites, corresponding to a ferromagnetic ordering of Co moments in hcp and fcc phases. The temperature dependence of Bhf for both phases, however, shows a sharp deviation from an expected standard Brillouin-like behavior for the host magnetization. The results are discussed in terms of a simple molecular-field model where the localized moment at impurity ions as well as the conduction electron contributions to the hyperfine field are taken into account.

Research paper thumbnail of Cd implantation in α−MoO3 : An atomic scale study

Physical Review Materials

Research paper thumbnail of Electric Field Gradient at Nb Site in the Intermetallic Compounds Nb3X (X = AI, In, Si, Ge, Sn) Measured by PAC

Zeitschrift für Naturforschung A

The electric field gradient (efg) at the Nb site in the intermetallic compounds Nb3X (X = Al, In,... more The electric field gradient (efg) at the Nb site in the intermetallic compounds Nb3X (X = Al, In, Si, Ge, Sn) was measured by the Perturbed Angular Correlation (PAC) method using the well-known gamma-gamma cascade of 133 -482 keV in 181Ta from the β- decay of 181Hf, substituting approximately 0.1 atom percent of Nb. The PAC results show that Vzz drops by nearly 40% when X changes from Al to In, and by about 25% when X changes from Si to Ge and Sn. This behavior is most probably related to the change in the degree of sp hybridization in these compounds. The Vzz values of the studied compounds do not follow the well known universal correlation for the efg's in non-cubic metals but the observed trend is well reproduced by results of ab-initio electronic structure calculations. In the case of Nb3 Al a linear temperature dependence of the quadrupole frequencies was observed in the temperature range of 6.5 to 1210 K.

Research paper thumbnail of Magnetic phase diagram of the solid solution LaMn2(Ge1−xSix)2 (0 ≤ x ≤ 1) unraveled by powder neutron diffraction

Scientific Reports

The structural and magnetic properties of the ThCr2Si2-type solid solution LaMn2(Ge1−xSix)2 (x = ... more The structural and magnetic properties of the ThCr2Si2-type solid solution LaMn2(Ge1−xSix)2 (x = 0.0 to 1.0) have been investigated employing a combination of X-ray diffraction, magnetization and neutron diffraction measurements, which allowed establishing a magnetic composition-temperature phase diagram. Substitution of Ge by Si leads to a compression of the unit cell, which affects the magnetic exchange interactions. In particular, the magnetic structure of LaMn2(Ge1−xSix)2 is strongly affected by the unit cell parameter c, which is related to the distance between adjacent Mn layers. Commensurate antiferromagnetic layers and a canted ferromagnetic structure dominate the Si-rich part of the solid solution, whilst an incommensurate antiferromagnetic flat spiral and a conical magnetic structure are observed in the Si-poor part.

Research paper thumbnail of The peculiarities of reduction and doping of vanadium oxides probed by TDPAC spectroscopy at ISOLDE

Research paper thumbnail of International Workshop on Utilization of Research Reactors, São Paulo, Brazil

Research paper thumbnail of Investigation of local magnetic properties of CeCd as a function of the unit cell volume by means of first principles calculations

Research paper thumbnail of Investigation of doping influence on local structure and phase transitions in vanadium oxides by time-differential perturbed angular correlations at ISOLDE-CERN

1 Instituto de Pesquisas Energéticas e Nucleares, IPEN, São Paulo, Brazil 2 Universidade Federal ... more 1 Instituto de Pesquisas Energéticas e Nucleares, IPEN, São Paulo, Brazil 2 Universidade Federal do Pará, Campus de Abaetetuba, Pará, Brazil 3 Instituto de Física da Universidade de São Paulo (IFUSP), São Paulo, SP, Brazil 4 Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina 5 EP Department, ISOLDE-CERN, CH-1211 Geneva 23, Switzerland 6 Institute for Materials Science and Center for Nanointegration, Duisburg-Essen (CENIDE), University of Duisburg-Essen, 45141 Essen, Germany 7 Centro de Ciências e Tecnologias Nucleares (CCTN), Instituto Superior Técnico, Universidade de Lisboa, Portugal 8 Chair of Department of Materials for Electronics, Technische Universität Ilmenau, Institute of Materials Science and Engineering, Gustav-Kirchhoff-Straße 5, 98693 Ilmenau, Germany

Research paper thumbnail of Investigation of hyperfine interactions in immunoglobulin G with perturbed angular correlation spectroscopy using 111Cd

Research paper thumbnail of O IPEN e a saúde

Research paper thumbnail of Huge negative magnetic hyperfine fields for 111Cd probe nuclei in the Fe3X (X=C, Ge, and Ga) compounds with specific properties

Research paper thumbnail of Effects of surfactant on the morphology of α-Bi2O3 synthesized by the Sol-gel method

Nano and micromaterial research, with a well-defined size and shape, has attracted attention from... more Nano and micromaterial research, with a well-defined size and shape, has attracted attention from researchers in the areas of chemistry, physics, engineering and biomedicine, due to the wide range of possible applications such as: health, environment, catalysis and miniaturization of electronic devices. In this sense, the chemical routes of synthesis, such as Sol-Gel, are more prominent because it allows the production of particulate materials and thin films, with controllable size and morphology. In this work, bismuth oxide microparticles were synthesized by the Sol-Gel method using metallic bismuth (99.999% purity) in acid solution. Initially, bismuth was diluted with nitric acid solution and distilled water. After dilution, citric acid (600 mg) and ethylene glycol were added. The volume of ethylene glycol was varied from 1 to 3.75 mL, in order to study the morphological effects of its concentration. The samples were then subjected to the calcination process at 673 K for 12 hours....

Research paper thumbnail of Insights into anomalous magnetic hyperfine field at Ce impurity in LaMn2X2 (X=Si, Ge)

Research paper thumbnail of Effects of an external magnetic field on the hyperfine parameters in RE2O3 (RE = Gd, Er) nanoparticles measured by perturbed angular correlation spectroscopy

AIP Advances, 2020

In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Pertu... more In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Perturbed Angular Correlation (PAC) spectroscopy, a local technique, plus external magnetic field, was used to elucidate local interactions and possible mapping of the different contribution in these compounds. NPs were synthesized by thermal decomposition and characterized by transmission electron microscopy and X-ray diffraction. PAC measurements were performed using 111In(111Cd) as probe nuclei, with and without the application of an external magnetic field (EMF) of 0.5 T in different temperatures (50 K, 100 K, 200 K, 300 K). Results show that the hyperfine magnetic field is almost zero when the probe is located at the symmetric site, and ∼4 T and ∼5 T for Gd2O3 and Er2O3, respectively, when the probe occupies the asymmetric field.

Research paper thumbnail of Effect of the magnetic impurity on the charge diffusion in highly dilute Ce doped LaMnO3

AIP Advances, 2020

LaMnO3+δ is a complex oxide, which, depending on the oxygen excess concentration, presents differ... more LaMnO3+δ is a complex oxide, which, depending on the oxygen excess concentration, presents different crystalline structure and interesting magnetic and electric properties such as colossal magnetoresistance, polaron dynamics, multiferroic behavior, and charge-orbital ordering. This complexity requires different characterization techniques to draw a picture as complete as possible allowing a good understanding of these phenomena. Here, we have used the perturbed angular correlation (PAC) technique to measure hyperfine interactions at La and Mn sites of LaMnO3+δ(δ ∼0.15) using 140Ce and 111Cd at La sites as probe nuclei in order to investigate within an atomic scale the magnetic and electric interactions in this compound. The results show that 111Cd nuclei occupy highly symmetric local sites in agreement with a rhombohedral structure. The magnetic hyperfine field (Bhf) measured with 111Cd at La sites is very small (Bhf = 0.40 T) due to the supertransferred magnetic field from Mn neigh...

Research paper thumbnail of Cd and In-doping in thin film SnO2

Journal of Applied Physics, 2017

In this paper, we investigate the effects of doping in the local structure of SnO2 by measuring t... more In this paper, we investigate the effects of doping in the local structure of SnO2 by measuring the hyperfine interactions at impurity nuclei using the Time Differential Perturbed Gamma-Gamma Angular Correlation (TDPAC) method in addition to density functional theory simulations. The hyperfine field parameters have been probed as a function of the temperature in thin film samples. The experimental results reveal that 117Cd/In and 111In/Cd are incorporated and stabilized in the SnO2 lattice replacing the cationic site. Significant differences in the electric field gradient were observed from TDPAC measurements with both the probe nuclei. Furthermore, the absence of strongly damped spectra further indicates that implanted Cd atoms (for 117Cd/In probe nuclei measurements) easily occupy regular substitutional Sn sites with good stability. The simulated value for the electric field gradient obtained with the first oxygen neighbor removed is closer to the experimental value observed for 1...

Research paper thumbnail of In and Cd as defect traps in titanium dioxide

Hyperfine Interactions, 2016

We present a study of TiO 2 single crystals from the point of view of the dopant atom that simult... more We present a study of TiO 2 single crystals from the point of view of the dopant atom that simultaneously behaves as the probing element. We used gamma-gamma time dependent perturbed angular correlations working with selected tracer elements (111 In/ 111 Cd, 111m Cd/ 111 Cd) together to investigate the different behavior of Cd and In dopants, particularly their interaction with point defects in the TiO 2 lattice. Results show that the hyperfine interactions observed at 111 Cd from 111 In or 111m Cd decay are quite different. 111 In/ 111 Cd results show a single site fraction characterized by a quadrupole frequency with asymmetry parameter similar to those observed for the same probe nuclei in bulk TiO 2 oxides. Results for 111m Cd/ 111 Cd reveal two site fractions, one characterized by the same hyperfine parameters to those measured in bulk TiO 2 and another fraction characterized by a quadrupole frequency and asymmetry parameters with higher values, as observed in thin This article is part of the Topical Collection on

Research paper thumbnail of Magnetic and transport properties assisted by local distortions in Bi 2 Mn 4 O 10 and Bi 2 Fe 4 O 9 multiferroic compounds

Journal of Alloys and Compounds, 2015

We have performed a comprehensive study on the magnetic and electrical properties through macrosc... more We have performed a comprehensive study on the magnetic and electrical properties through macroscopic and local characterizations on Bi 2 Mn 4 O 10 and Bi 2 Fe 4 O 9. An analysis of the temperature evolution of local distortions, which was obtained by perturbed angular correlation measurements, revealed an anomalous behavior of the quadrupolar frequency and asymmetry parameter below the antiferromagnetic ordering temperature for both samples. The combined results suggest correlations between magnetic, electric, and elastic interactions. At high temperature, we have observed that the hopping frequency and activation energy in the electrical transport mechanism are close related to hyperfine parameters, electrical field gradient and asymmetry parameter, due to modifications in the equilibrium positions of oxygen atoms conforming octahedral, pyramidal, and tetrahedral environments. Anharmonic lattice effects are much more pronounced in a temperature range close to room temperature.

Research paper thumbnail of Local investigation with radioactive probe of wide band gap oxides thin films doped with transition metals

Local investigation with radioactive probe of wide band gap oxides thin films doped with transiti... more Local investigation with radioactive probe of wide band gap oxides thin films doped with transition metals.

Research paper thumbnail of Investigation of Rare Earth (RE = La, Dy, and Er) doping of HfO2 by perturbed angular correlation spectroscopy