Artur Wilson Carbonari

University of São Paulo | USP · Instituto de Pesquisas Energéticas e Nucleares (IPEN)

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 appli...

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 appro...

In recent years, the synthesis of all-inorganic halide perovskite Cs(Pb, Sn)X 3 (X = Cl, Br, and I) quantum dots (QDs) and the study of their physical properties have been of great interest due to their high potential as photoactive materials in optoelectronic technologies. Indeed, this family of semiconductors exhibits an ultralow thermal conducti...

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...

The article describes a methodology combining experimental and theoretical approaches to investigating doping in oxide semiconductors

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 compres...

Recently, a model based on a combined ab initio/time-differential perturbed γ−γ angular correlation (TDPAC) study in the In111(→Cd111)-doped SnO2 semiconductor was proposed to enlighten the origin of the dynamic hyperfine interactions (HFIs) observed in oxides after the electron-capture (EC) decay of the probe nucleus of the In111 parent. It was de...

The structural and magnetic properties of the ThCr 2 Si 2 -type solid solution LaMn 2 (Ge 1− x Si x ) 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...

In this work Fe3O4:Er nanoparticles (NPs) with the characteristic size of ~ 11 nm were synthesized via classic co-precipitation method. Electron microscopy and X-ray diffraction were employed to probe the morphology and structure of the samples. Results revealed that samples synthesized in the Fd-3mZ structure with lattice constant close to that of...

The Ce(1−x)LaxCrGe3 (x=0, 0.19, 0.43, 0.58, and 1) intermetallic compound system has been investigated by magnetization measurements and neutron scattering techniques to determine the effect of La doping on the magnetic ordering and exchange interaction between Cr ions. The structural and magnetic characterization in this series was first verified...

We herein report a comprehensive investigation on the magnetic, structural, and electric properties of CoO nanoparticles with different sizes by local inspection through hyperfine interactions measured in a wide range of temperatures (10–670 K) by using radioactive 111\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepacka...

The Ce(1-x)LaxCrGe3 (x = 0, 0.19, 0.43, 0.58 and 1) intermetallic compound system has been investigated by magnetization measurements and neutron scattering techniques to determine the effect of La-doping on the magnetic ordering and exchange interaction between Cr ions. The structural and magnetic characterization in this series was first verified...

A detailed investigation of the electronic structure in the neighborhood of Cd impurities in CeO2 has been performed by ab initio calculations to elucidate the interplay between the oxygen vacancies and electric quadrupole interactions. The quadrupole frequency related to the major component of the electric-field gradient (EFG) at impurities sites...

We herein report a comprehensive investigation on the magnetic, structural, and electric properties of CoO nanoparticles with different sizes by local inspection through hyperfine interactions measured in a wide range of temperatures (10-670 K) by using radioactive 111In( 111Cd) tracers with the perturbed angular correlations (PAC) technique. Small...

In the work here reported, we have calculated magnetic hyperfine interactions in rare-earth (R) intermetallic compounds by using the free open-source all-electron ELK code. The RCd (R = Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) series was chosen as a test system because an almost complete set of experimental data on the hyperfine paramete...

GdMnIn is reported to crystallize in the hexagonal MgNi2-type structure presenting a spin-glass behavior with no magnetic order attributed to the triangular spin frustration of magnetic ions. In the present work, FC-ZFC magnetization, specific heat and AC susceptibility measurements along with the local magnetic exchange measured by hyperfine inter...

Nanoparticles (NPs) that combine biocompatibility and enhanced physical characteristics for biomedical applications are currently an area of intense scientific research. Hafnium oxide NPs are 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 rad...

The enhancement of nanoparticle’s magnetic properties with a suitable coating is the main tool to increase their potential as an effective candidate for applications in different areas, especially in biomedicine. In the work here reported, Fe3O4 nanoparticles coated with natural oils were synthesized by iron (III) acetylacetonate thermal decomposit...

This paper presents the results of time-differential perturbed gamma–gamma angular correlation measurements of SnO2 thin films carried out in an applied magnetic field. The measurements were performed upon the implantation of Fe at 80 keV and ¹¹¹In (¹¹¹Cd) at 160 keV. The samples were further characterized by energy-dispersive X-ray spectroscopy. T...

The Pechini-type sol-gel (PSG) process has been used for the preparation of doped oxides due to its capability to overcome most of the difficulties that frequently occur by using other producing methods. In this work we analyze the case of samples of pure and In-doped yttria (Y2O3) prepared by the PSG process. We experimentally characterize the syn...

Among the various approaches to grow semiconducting oxide nanowires, the thermal oxidation procedure is considered a simple, efficient, and fast method that allows the synthesis of micro and nanostructured arrangements with controlled size and morphology. In the work reported in this paper, long ZnO nanowires were synthesized on the surface of oxid...

Tuning the electrical properties of materials by controlling their doping content has been utilized for decades in semiconducting oxides. Here, an atomistic view is successfully employed to obtain local information on the charge distribution and point defects in Cd-doped SnO 2. We present a study that uses the time-differential perturbed gamma-gamm...

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...

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 a...

Due to its rich variety of electromagnetic properties, such as a colossal magnetoresistance, charge and orbital ordering, and metal-insulator transition, the magnetic behavior in La0.5Ba0.5MnO3 double perovskite compounds has been investigated by several techniques, however more experimental data, especially from atomic resolution techniques, are s...

A new method of synthesis of hafnium silicate HfSiO4 (also known as hafnon) is reported. We observed a self-controlled 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 b...

In this paper we investigate the effect of Cd doping at ultra-low concentrations in SnO$_2$ both experimentally, by measuring the temperature dependence of the electric quadrupole hyperfine interactions with time-differential perturbed angular correlation (TDPAC) spectroscopy using $^{111}$Cd as probe nuclei, and theoretically, by performing first-...

In the investigation reported in this paper a modified thermal decomposition method was developed to produce very small Er₂O₃ nanoparticles. Particles structure, shape and size were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) which showed that the synthesis by thermal decomposition under...

Magnetic hyperfine field has been measured in the orthorhombic intermetallic compound LaMnSi2 with perturbed angular correlation (PAC) spectroscopy using radioactive ¹⁴⁰La(¹⁴⁰Ce) nuclear probes. Magnetization measurements were also carried out in this compound with MPSM-SQUID magnetometer. Samples of LaMnSi2 compound were prepared by arc melting th...

In the work reported in this paper, the temperature dependence of the magnetic hyperfine field (Bhf) at ¹⁴⁰Ce nuclei replacing Pr atoms in PrMn2Ge2 compound was measured by the perturbed angular correlation technique to complete the sequence of measurements in REMn2Ge2 (RE = La, Ce, Pr, Nd). Results show an anomalous behavior different from the exp...

The Pechini sol-gel method has been employed for the synthesis of pure and (¹⁸¹Hf→)¹⁸¹Ta-doped Y2O3 nanopowders. We performed a structural characterization from the micro to the subnanoscopic scale by means of scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, and time-differential perturbed γ-γ angular correlati...

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...

Here we report time differential perturbed angular correlation (TDPAC) results of Co-doped SnO2 thin films. Making use of stable Co and radioactive 111In implanted at the Bonn Radioisotope Separator with energies of 80 keV and 160 keV, respectively, it was possible to study the dopant incorporation and its lattice location during annealing. The hyp...

The local environment in titanium dioxide was studied by the time differential perturbed γ-γ angular correlation of 111 In/ 111 Cd and 181 Hf/ 181 Ta at the HISKP, Bonn. An introduction to the implantation methodologies performed at the Bonn Radioisotope Separator is presented. The investigation was carried out on thin films, which were deposited b...

The local environment in titanium dioxide was studied by the time differential perturbed γ-γ angular correlation of 111In/111Cd and 181Hf/181Ta at the Helmholtz-Institut für Strahlen-und Kernphysik, Bonn. An introduction to the implantation methodologies performed at the Bonn Radioisotope Separator is presented. The investigation was carried out on...

In this paper, the effect in structural and magnetic properties of irondoping 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 m...

The magnetic properties of PrMn2Ge2 compound have been investigated by perturbed γ-γ angular correlation (PAC) spectroscopy using ¹¹¹In(¹¹¹Cd) as probe nuclei as well as by magnetization measurements. This ternary intermetallic compound exhibits different magnetic structures depending on the temperature. The magnetic ordering is mainly associated w...

We present a study of TiO2 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 (¹¹¹In/ ¹¹¹Cd, 111mCd/ ¹¹¹Cd) together to investigate the different behavior of Cd and In dopants, particular...

This paper reports the investigation of the magnetic hyperfine field Bhf in a series of rare-earth (R) cadmium intermetallic compounds RCd and GdCd2 measured by perturbed angular correlation (PAC) spectroscopy using In111/Cd111 as probe nuclei at Cd sites as well as first-principles calculations of Bhf at Cd sites in the studied compounds. Vapor–so...

Magnetic nanoparticles of magnetite have been synthesized by thermal decomposition and investigated by measuring the magnetic hyperfine field. Preformed Fe3O4 nanoparticles were used as seeds to produce of a series of magnetic nanoparticles, with different sizes and shapes. Samples were characterized by X-ray diffracton, transmission electron micro...

The magnetic hyperfine field (Bhf) in ferrimagnetic GdCo5 compound has been investigated as a function of temperature by Mössbauer effect (ME) spectroscopy and perturbed angular correlation(PAC) spectroscopy using 119Sn and 111Cd probe nuclei, respectively. Results show that the non-magnetic probe atoms 119Sn and 111Cd substitute all three non-equi...

The magnetic behavior of Gd2O3nanoparticles, produced by thermal decomposition method and subsequently annealed at different temperatures, was investigated by magnetization measurements and, at an atomic level, by perturbed γ − γ angular correlation (PAC)spectroscopymeasuringhyperfineinteractions at 111In(111Cd) probe nuclei. Nanoparticlestructure,...

We report both coaxial core-shell structured microwires and ZnO microtubes with growth of nanosticks in the inner and nanowires on the outer surface as a novel hierarchical micro/nanoarchitecture. First, a core-shell structure is obtained—the core is formed by metallic Zn and the semiconducting shell is comprised by a thin oxide layer covered with...

In the past years nanotechnology has been distinguishing as a quick growing field, with many medical applications including drug delivery and medical images. For medical procedures gold nanoparticles (AuNPs) have been widely studied. The characteristics that make this material a good option to improve radiosensitivity in a specific tissue are their...

In this paper, first-principles calculations based on density functional theory (DFT) were used to determine TM (TM=Fe, Ni, Co) and Cd impurity locations in the In2O3 host structure, their charge states, the electronic and structural relaxations induced in the host lattice as well as to interpret previous and supplementary experimental results of h...

The magnetic behavior of the intermetallic compound NdMn2Ge2 was investigated by bulk magnetization measurements and measurements of hyperfine interactions using perturbed γ–γ angular correlation (PAC) spectroscopy. Magnetization measurements indicate the presence of four magnetic transitions associated with the Mn and Nd magnetic sublattices. At h...

In this paper, the local magnetic properties of La-doped Fe3O4 (5% and 10%) bulk and Nanoparticles (NPs) samples were studied by measuring hyperfine interactions in a wide range of temperature from 10 to 900 K with perturbed γ-γ angular correlation spectroscopy using 111In(111Cd) and 140La(140Ce) as probe nuclei. Results for the temperature depende...

Magnetic hyperfine field at Mn site has been measured in the orthorhombic intermetallic compound LaMnSi2 with PAC spectroscopy using radioactive 111In- 111Cd nuclear probe. Samples of LaMnSi2 were prepared by melting pure metallic components in stoichiometric proportion in an arc furnace under argon atmosphere. The samples were sealed in a quartz t...

Time differential perturbed angular correlation (TDPAC) measurements were carried-out on PbZr0.8Ti0.2O3 as a function of temperature. A broad distribution of electric field gradient (EFG) was observed in all cases with a second site for 181Hf-181Ta probes in the R3c phase. The results were analyzed in terms of a model which simulates an attraction...

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 wellknown 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 drop...

In this work, the perturbed angular correlation (PAC) spectroscopy is used to study differences in the nuclear quadrupole interactions at Cd probes in DNA molecules of mouse infected with the Y-strain of Trypanosoma cruzi (T. cruzi). The possibility of investigating the local genetic alterations in DNA, that occur along generations of mice infected...

The temperature dependence of the magnetic hyperfine field (Bhf) at Mn atom sites was measured in LaMn2(Si(1-x)Gex)2, with 0 ≤ x ≤ 1, compounds with perturbed γ -γ angular correlation spectroscopy using 111In(111Cd) as probe nuclei in the temperature range from 20 K to 480 K. The results show a transition from antiferromagnetic to ferromagnetic ord...

The effect of substitution of Ge for Si in LaMn2Si2 compound on the magnetic hyperfine field (Bhf) has been investigated by perturbed γ-γ angular correlation (PAC) spectroscopy using 140La(140Ce) as probe nuclei. This compound exhibits antiferromagnetism followed by a ferromagnetic ordering when temperature decreases. The behavior of the ferromagne...

Nuclear quadrupole interactions at Zn sites in the intermetallic compounds RZn (R = Ce, Gd, Tb, Dy) have been investigated by perturbed gamma-gamma angular correlation (PAC) spectroscopy using 111In(111Cd) as probe nuclei. Measurements were carried out in the temperature range of 10–295 K. These compounds exhibit CsCl type cubic structure and while...

The magnetic and electric hyperfine interactions of the nuclear probe 111 Cd in the hexagonal antiferromagnetic rare earth-gallium RGa 2 (R ¼ Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er) intermetallic compounds have been investigated by perturbed angular correlation (PAC) spectroscopy as a function of temperature. With the exception of R ¼ Nd and Ho, th...

The magnetic and electric hyperfine interactions of the nuclear probe 111Cd in the hexagonal antiferromagnetic rare earth-gallium RGa2 (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er) intermetallic compounds have been investigated by perturbed angular correlation (PAC) spectroscopy as a function of temperature. With the exception of R = Nd and Ho, the...

In the present work, an experimental and theoretical study of the hyperfine interactions at Gd and In sites in GdIn3 were performed. The experimental measurements were carried out by perturbed angular correlation spectroscopy using 140Ce and 111Cd nuclear probes substituting Gd and In sites, respectively. Results for 111Cd probe at In sites in GdIn...

The magnetic hyperfine field (Bhf) in RZn compounds (R = Gd, Tb, Dy) has been investigated by perturbed angular correlation spectroscopy using 140Ce and 111Cd as probe nuclei, respectively, at R and Zn sites, in order to study the origin of the magnetic coupling in these compounds. The results for 111Cd probe showed that the temperature dependence...

The structural and magnetic properties of GdNiIn intermetallic compound and its hydride have been studied. The GdNiIn compound crystallizes in the ZrNiAl-type structure. The structural study indicates that after hydrogenation the crystal structure remains the same and suggests that hydrogen atoms likely occupy 4h and 2d interstitial sites; meanwhil...