| dc.creator | SALES, T.S.N. | |
| dc.creator | CARBONARI, A.W. | |
| dc.creator | 60 YEARS OF IEA-R1: INTERNATIONAL WORKSHOP ON UTILIZATION OF RESEARCH REACTORS | |
| dc.date | 2018-03-20T12:50:46Z | |
| dc.date | 2018-03-20T12:50:46Z | |
| dc.date | November 28 - December 01, 2017 | |
| dc.date.accessioned | 2023-09-28T14:07:05Z | |
| dc.date.available | 2023-09-28T14:07:05Z | |
| dc.identifier | http://repositorio.ipen.br/handle/123456789/28781 | |
| dc.identifier.uri | https://repositorioslatinoamericanos.uchile.cl/handle/2250/8999029 | |
| dc.description | Nanoparticles have attracted a great deal of interest due to their desirable properties
suited for technological and medical applications. Hafnium dioxide (HfO2)
can be used in both areas. Simple and low-cost synthesis of HfO2 as thin films or
nanoparticles are, therefore, very important for applicability of these materials. The
sol-gel method of synthesis besides fulfilling these characteristics also allows an efficient
controlled doping of HfO2 with different elements to improve its properties. In
this work, we investigated the effects of the doping with 5 at.% of silicon in HfO2
nanoparticles prepared by the sol-gel method by measuring hyperfine interactions at
181Ta probe nuclei on Hf sites using the
????
perturbed angular correlations (PAC)
spectroscopy.
The HfO2 powder was obtained by sol-gel method from high purity Hf (99.99%)
and Si (99.99%) elements. Initial colloid includes Hf and Si dissolved in appropriated
acids, citric acid and ethylene glycol all in stoichiometric proportion. The solution
(sol) was heated to 100 C until gel aggregation. After that, the solution was calcined
in air at 550 C for 14 hours in order to evaporate organic materials present in the
gel.
Part of the resulting powder had their structure investigated by X-ray diffraction
(XRD). Another part was irradiated with neutrons in the IEA-R1 research reactor of
IPEN to produce radioactive 181Hf(181Ta) to carry out hyperfine interactions measurements
by PAC. This methodology has the advantage to assure an extremely low
concentration and highly homogenous distribution of probe nuclei along with a very
well defined location of them. These features enable the investigation of different
regions inside the nanoparticles, within an atomic resolution, concerning point defects
and formation of other phases. Hyperfine paramenters were measured within
the range from 200 C to 900 C. XRD results showed a single phase with the expected
monoclinic structure for the as-prepared samples indicating that Si atoms are
at substitutional Hf sites. However, PAC results for the electric field gradient and
asymmetry parameter measured with 181Ta probe at 600 C indicate that Si dopants can induce dislocation of Hf atoms from their native location in HfO2 throughout
the lattice. | |
| dc.format | 79-80 | |
| dc.publisher | Instituto de Pesquisas Energ??ticas e Nucleares | |
| dc.rights | openAccess | |
| dc.title | Effect of silicon doping in HfO2 nanoparticles from an atomic view | |
| dc.type | Resumo de eventos cient??ficos | |
| dc.coverage | I | |
| dc.local | S??o Paulo, SP | |
