W. Strek

Neodymium(III) doped fluoride nanoparticles as non-contact optical temperature sensors

We report that non-contact optical temperature sensing can be achieved with the use of heavily Nd(3+) doped NaYF(4) nanoparticles. The temperature evaluation can be realized either by monitoring the absolute luminescence intensity or by measuring the intensity ratio of the two Stark components of the (4)F(3/2) multiplet in the Nd(3+) ions.

Optical properties of Eu(III) chelates trapped in silica gel glasses

Abstract Preparation and optical properties of silica gel glasses doped with Eu(III) chelates (the complexes of β-diketones) are described. In particular the emission and excitation spectra of the precursor salts and glasses are reported. The assignment of electronic levels was proposed and the intensity analysis of the f–f transitions was performed. The decay times of 5D0 levels of Eu(III) complexes in gels are analyzed and compared with those reported for precursor salts.

White emission of lithium ytterbium tetraphosphate nanocrystals.

An efficient anti-Stokes white broadband emission induced by 976 nm laser diode in lithium ytterbium tetraphosphate (LiYbP4O12) nanocrystals was investigated. The emission occurs at room temperature and atmospheric pressure. Its intensity demonstrates an evident threshold dependence on the temperature and excitation density characteristic to avalanche process. The white emission is accompanied by very efficient photoconductivity characterized by microampere photocurrent which increases with the fourth order of applied incident light power (~P4). We show that this emission is critically dependent on temperature and increases significantly in vacuum. It is concluded that the anti-Stokes white emission is associated with theYb3+- CT luminescence.

Rare-earth doped nanocrystalline phosphors for field emission displays

The cathodoluminescence properties of rare-earth (RE = Ce, Eu, Tb) doped nanocrystalline phosphors (Y2O3, Y3Al5O12) were investigated. Their structure and morphology were determined and correlated with optical properties. The effect of grain sizes on emission yield of RE doped nanophosphors has been investigated. A possibility of application of RE doped nanophosphors for efficient field emission display (FED) devices has been discussed.

Nanomaterials containing rare-earth ions Tb, Eu, Er and Yb: preparation, optical properties and application potential

This paper focuses on preparation, optical properties and application potential of some nanomaterials based on Y2O3:Eu,Tb,Er,Yb and SiO2–TiO2 and SiO2–ZiO2 doped with Er and Yb. Y2O3 nanophosphors are prepared by the combustion method with different doped concentrations. The nanocrystal size of Y2O3:Eu is from 4.4 to 72.2 nm depending on the technology condition. The luminescent spectra, up-conversion and lifetimes were measured and compared. The influence of the technological conditions on the luminescent properties was investigated in detail. The energy transfer effect was studied by the luminescent spectra and the lifetimes in the temperature dependence for the samples with rare-earth concentrations of 5 mol%, The relative concentration between Eu and Tb is 8/2 for energy transfer from Tb to Eu. The SiO2–TiO2 and SiO2–ZiO2 thin films containing Er rare-earth ion were prepared by the sol–gel technique. Optical properties were investigated and the influence of the Er concentration on the luminescent spectra as well as the influence of the Ti concentration on the refractive index of thin films was presented.

Power dependence of luminescence of Tb3+ -doped KYb(WO4)2 crystal

Abstract The effect of excitation intensity on luminescence properties of Tb3+-doped KYb(WO4)2 crystal is reported. In particular, emissions following the Stokes and anti-Stokes excitations were investigated. It was found that, in addition to the Tb3+ luminescence, an intense Yb3+ luminescence at room temperature was observed after a direct excitation of Tb3+ ions in spite of the fact that both ions are far off-resonance. The intensities of Tb3+ and Yb3+ luminescences were dependent on the excitation power and changed by a sublinear function (slope

Emission properties of nanostructured Eu3+ doped zinc aluminate spinels

Abstract The preparation of nanostructured ZnAl2O4 spinel powders doped with Eu3+ ions obtained by a hydrothermal method is described. XRD analyses demonstrated that the powders were single-phase spinel nanopowders with high crystallite dispersion. The averaged spinel particle size was determined to be 6 nm as prepared and it increased up to 8 nm for calcination at 500°C. The emission spectra of Eu3+ ions measured for the samples calcinated at 500°C demonstrated inhomogeneous shapes characteristic for disordered material which after heating at 1500°C changed shape into an ordered shape characteristic of the crystalline form.

Preparation and optical properties of nanocrystalline and nanoporous Tb doped alumina and zinc aluminate

Abstract Preparation and morphology of nanocrystalline and nanoporous ceramics composed of a network of alumina and zinc aluminate doped with Tb ions are reported. The pore size distributions are determined by nitrogen adsorption at 77 K. The emission spectra and lifetimes of Tb 3+ ions were measured. The effect of thermal conditions of preparation on emission properties was investigated. It is concluded that with increasing thermal heating the sizes of nanoparticles increase leading to the cluster formation of Tb 3+ ions.

Precursor and solvent effects in the nonhydrolytic synthesis of complex oxide nanoparticles for bioimaging applications by the ether elimination (Bradley) reaction.

Investigation of the solvent and alkoxide precursor effect on the nonhydrolytic sol-gel synthesis of oxide nanoparticles by means of an ether elimination (Bradley) reaction indicates that the best crystallinity of the resulting oxide particles is achieved on application of aprotic ketone solvents, such as acetophenone, and of smallest possible alkoxide groups. The size of the produced primary particles is always about 5 nm caused by intrinsic mechanisms of their formation. The produced particles, possessing the composition of natural highly insoluble minerals, are biocompatible. Optical characteristics of the perovskite complex oxide nanoparticles can easily be controlled through doping with rare earth cations; for example, by Eu(3+). They can be targeted through surface modification by anchoring the directing biomolecules through a phosphate or phosphonate moiety. Testing of the distribution of Eu-doped BaTiO(3) particles, modified with ethylphosphonic acid, demonstrates their facile uptake by the plants with active fluid transport, resulting finally in their enhanced concentration within the cell membranes.

Optical behavior of Eu3+-doped BaTiO3 nano-crystallites prepared by sol–gel method

Abstract Eu 3+ -doped BaTiO 3 nano-crystallites with grain sizes 32–38 nm have been obtained by a sol–gel method. It has been found that the luminescence characteristics are strongly dependent on the sintering temperature. Powders sintered at temperatures below 1000 °C demonstrate a luminescence behavior at room temperature associated with a lack of the inversion symmetry of Eu 3+ sites. Above 1000 °C nano-crystallites undergo a phase transition characterized by an inversion symmetry of Eu 3+ sites. The size effect of Eu 3+ :BaTiO 3 nano-crystallites on luminescence characteristics is observed.