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Positronium Probing of Pores in Zirconia Nanopowders

100%

Prochazka I., Cizek J., Lukac F., Melikhova O., Hruska P., Anwand W., Liedke M., Konstantinova T., Danilenko I.

Acta Physica Polonica A

2017

vol. 132

issue 5

1564-1567

In the present paper, conventional positron lifetime measurements on selected zirconia-based nanopowders are reported. The nanopowders were doped with various metal cations (Y³⁺, Eu³⁺, Gd³⁺, Lu³⁺ and Mg²⁺). Lifetime experiments were conducted in air and supplemented with mass density measurements. In a range of lifetimes, from a few ns to ≈70 ns, up to two individual lifetime components could be identified. Such observations confirmed positronium (Ps) formation with subsequent ortho-Ps pick-off annihilation as well as the occurrence of pores of different size. Pore sizes were estimated using a shape-free model of the correlation between pore size and ortho-Ps lifetime. The origins of pores are discussed on the basis of the ortho-Ps data in combination with the results of mass density measurements.

Luminescent properties and the morphology of SrMoO4:Eu3+ powders synthesized via combining sol-gel and solid-state route

84%

Wei Q., Chen D.

Open Physics

2010

vol. 8

issue 5

766-770

SrMoO4:Eu3+ red phosphors were prepared by combining sol-gel and solid-state route. Citric acid and ethylenediaminetetraacetic acid (EDTA), employed as the chelating agents, were added to the aqueous solutions of metal nitrates. X-ray diffraction (XRD) and photoluminescent spectra techniques (PL) were used to characterize the resultant powders. The results indicated the obtained SrMoO4:Eu3+ phosphors were fine powders with a particle size of 50 nm. The effects of synthesizing conditions were also investigated and optimized, which included the synthesis temperature and the activator concentration on the luminescent intensity. Compared with SrMoO4:Eu3+ phosphors prepared by Solid-state reaction SrMoO4:Eu3+ phosphors prepared by combining sol-gel and solid-state route showed appropriate particle size and a higher emission intensity.

Positron Annihilation in Magnetite Nanopowders Prepared by Co-Precipitation Method

68%

Durak K., Wiertel M., Surowiec Z., Miaskowski A.

Acta Physica Polonica A

2017

vol. 132

issue 5

1593-1597

Nanosized iron oxide powders are materials considered with regard to its application in medical therapy called hyperthermia. Magnetite nanopowders with crystallite size varying from 6.6 to 11.8 nm have been prepared by the co-precipitation method. In this study a change of a crystallite size is driven mainly by varying of initial pH of water ammonia solution in which a process of magnetite precipitation runs. Crystallographic structures and phase composition obtained samples and the size of magnetite nanoparticles were determined by X-ray diffraction method. Positron lifetime spectroscopy has been used to assess defectiveness of microstructure. Experimental positron annihilation spectra were successfully resolved into three lifetime components. It appears that from point of view of microstructure the defects concentrations in studied nanopowder samples are very high which causes a saturation of positron trapping.

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2 Acta Physica Polonica A

1 Open Physics

2 2017

1 2010

1 Anwand W.

1 Chen D.

1 Cizek J.

1 Danilenko I.

1 Durak K.

1 Hruska P.

1 Konstantinova T.

1 Liedke M.

1 Lukac F.

1 Melikhova O.

1 Miaskowski A.

1 Prochazka I.

1 Surowiec Z.

1 Wei Q.

1 Wiertel M.

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Positronium Probing of Pores in Zirconia Nanopowders

Luminescent properties and the morphology of SrMoO4:Eu3+ powders synthesized via combining sol-gel and solid-state route

Positron Annihilation in Magnetite Nanopowders Prepared by Co-Precipitation Method