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Structure and properties of polyurethane/YAG:Tb3+ nanocomposites with luminescence properties

Ryszkowska J., Zawadzak E., Hreniak D., Stręk W., Kurzydłowski K. J.

Polimery

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2007

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T. 52, nr 5

340-344

EN

Elastic polyurethanes films with luminescent properties have attracted increasing attention, both as a subject of fundamental and applied research. In the present study, polyurethane nanocomposites containing 0.05 to 0.2 wt. % of nanofillers were prepared by in situ polymerization. These nanocomposites were subsequently used to investigate the influence of the nanoparticles’ content on their structure and properties. PUR was synthesized using polycaprolactone diol (PCL diol) and dicyclohexylmethane-4,4’-diisocyanate (HMDI) with addition of diols as chains extenders. The nanofiller in the form of yttrium-aluminum-garnet (YAG) containing 10 wt. % of Tb3+ was added and samples of composites were synthesized employing prepolymer fabrication route. Series of nanocomposites with exhibited high luminescence and intensity of emission. Microstructure of these composites was investigated using atomic force microscopy (AFM) in a tapping mode. The grain size analysis of nanofillers was performed with high resolution scanning electron microscopy (HRSEM) and high resolution transmission electron microscopy (HRTEM). The mechanical and optical properties of the specimens have been correlated to their microstructure.

PL

Elastyczne folie poliuretanowe o właściwościach luminescencyjnych są przedmiotem dużego zainteresowania ze względu na różnorodność ich zastosowań. Jedną z potencjalnych możliwości ich wykorzystania jest zabezpieczanie dokumentów. W ramach tej pracy zbadano wpływ zawartości nanonapełniacza na strukturę oraz właściwości otrzymanych kompozytów. Do syntezy nanokompozytów użyto poli(?-kaprolaktano)diolu (PCL diol), 4,4’-diizocyjanian dicykloheksylometanu (HMDI) oraz dioli jako przedłużaczy łańcucha. Nanokompozyty otrzymano metodą in situ z mieszaniny substratów w procesie syntezy prowadzonej metodą prepolimerową. Jako nanonapełniacza użyto kryształów granatu itrowo-glinowego (YAG) domieszkowanego 10% mas. Tb3+, dodając go w ilości od 0,05 do 0,2% mas. w stosunku do całej masy polimeru. Otrzymane nanokompozyty z różną zawartością nanonapełniacza charakteryzowały się wysoką przeświecalnością oraz intensywnością emisji (tabela 1, rys. 3). Za pomocą mikroskopu sił atomowych (AFM) wykonano analizę mikrostruktury otrzymanych próbek (rys. 2). Analizę wielkości ziarna nanonapełniacza przeprowadzono za pomocą wysokorozdzielczego skaningowego mikroskopu elektronowego (HRSEM) oraz wysokorozdzielczego transmisyjnego mikroskopu elektronowego (HRTEM) (rys. 1). Określono korelację pomiędzy właściwościami mechanicznymi (tabela 4) i optycznymi otrzymanych kompozytów, a mikrostrukturą nanokompozytów.

2

Preparation and upconversion properties of Er3+,Yb3+:Y2Si2O7 nanocrystallites embedded in PVA polymer nanocomposites

Hreniak D., Głuchowski P., Stręk W., Bettinelli M., Kozłowska A., Kozłowski M.

Materials Science Poland

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2006

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Vol. 24, No. 2/1

405--413

EN

The preparation of polymer nanocomposites consisting of poly(vinyl) alcohol (PVA) network and RE3+:Y2Si2O7 nanocrystalline particles (RE=Yb, Er) is presented. The optical properties of the nanocomposite were preliminarily studied. In particular, efficient upconversion was observed in Er3+ and Yb3+ codoped Y2Si2O7 nanoparticles embedded in the polymeric PVA host. It was found that the luminescence features of the RE3+:Y2Si2O7 nanoparticles were affected by the polymeric host, resulting in a shortening of the luminescence lifetimes. This effect is discussed in terms of effective refractive index.

3

Formation of nanostructured Tb3+-doped yttrium aluminium garnets by the glycol route

Mazur P., Hreniak D., Niittykoski J., Stręk W., Hölsä J.

Materials Science Poland

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2005

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Vol. 23, No. 1

261--268

EN

Terbium-doped nanocrystalline yttrium aluminium garnet phases, Y3Al5O12:Tb3+ (YAG:Tb3+), were obtained by using rare-earth nitrates as the starting materials, together with citric acid and ethylene glycol according to the Pechini method. Thermogravimetric and differential thermal analysis were used to study the thermal decomposition of the precursor gels and the formation of nanocrystalline YAG:Tb3+. An increase in garnet nanocrystallite size from 20 to 40 nm with annealing temperature increasing from 800 to 1160 °C was evidenced with X-ray powder diffraction measurements. The intensity as well as the decay times of both 5D3 and 5D4 emissions of Y3Al5O12:Tb3+ were not found to depend on annealing and were thus independent of crystal size.

4

Synthesis and luminescence properties of nanocrystalline BaTiO3:Nd3+ obtained by sol-gel methods

Pązik R., Hreniak D., Stręk W.

Materials Science Poland

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2004

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Vol. 22, No. 3

210--225

EN

Neodymium-doped barium titanate (BaTiO3) nanocrystalline powders were prepared by the sol-gel method. Structure and average grain sizes were analysed by X-ray powder diffraction (XRD) measurements. Grain sizes amount from 30 to 60 nm, depending on dopant concentration and sintering temperature. The luminescence properties of BaTiO3:Nd3+ were investigated as a function of the concentration of Nd3+ (0.5-2 mol %) and sintering temperature (700-1050 ?C). The influence of Nd3+ concentration on the grain size and crystal structure of BaTiO3 nanocrystallite powders was found and a weak hot emission from the 4F5/2 level was observed for the nanopowders obtained.

5

Optical properties of Eu(III) doped nanocrystalline films of TiO2

Hreniak A., Nyk M., Hreniak D., Stręk W., Kępiński L., Misiewicz J., Maruszewski K.

Materials Science Poland

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2004

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Vol. 22, No. 3

227--234

EN

The synthesis of europium (III) doped nanocrystalline TiO2 films is described. The morphology and structure of the films were determined by transmission electron microscopy (TEM) and the selected area of electron diffraction (SAED) method. The photoluminescence (PL), lifetimes and cathodoluminescence (CL), recorded at room temperature, are reported. It has been found that the cathodoluminescence characteristics are significantly different from the photoluminescence ones. It is concluded that different Eu3+ sites contribute to the optical behaviour of Eu3+:TiO2 films.

6

Preparatyka i właściwości luminescencyjne nanomateriałów dielektrycznych domieszkowanych jonami ziem rzadkich.

Hreniak D., Stręk W., Wrzyszcz J.

Archiwum Nauki o Materiałach

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2003

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T. 24, nr 4

611-625

PL

Przedstawione zostały metody syntezy nanorozmiarowych kryształów zawierających optycznie aktywne jony ziem rzadkich. W szczególności omówiono metody hydrotermalne, zol-żelowe i Pechini'ego oraz przedstawiono podstawowe właściwości strukturalne i spektroskopowe wybranych nanokryształów ZnAl2O4, BaTiO3, Al2O3-ZrO2 i Y3Al5O12 domieszkowanych jonami Eu 3+, Nd 3+ i Tb 3+.

EN

Techniques of preparation of nanosized crystals doped with rare earth ions have been presented. Particularly, hydrothermal, sol-gel and Pechini's methods have been described. Structural and spectroscopic properties of selected ZnAl2O4, BaTiO3, Al2O3-ZrO2 and Y3Al5O12 doped with Eu 3+, Nd 3+ and Tb 3+ ions have been investigated.

7

Structure, spectroscopy and dielectric properties of BaTiO3:Eu3+ nanocrystallites prepared by the sol-gel method

Hreniak D., Łukowiak E., Maruszewski K., Pązik R., Stręk W.

Materials Science

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2002

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Vol. 20, No. 1

43-50

EN

Eu3+-doped BaTiO3 nanocrystalline powders have been obtained by sol-gel method. Their morphology, structure and dielectric properties have been investigated as a function of sintering temperature. The powders sintered at the temperatures below 800 st.C demonstrate luminescence behaviour characteristic of the inversed symmetry Eu3+ sites, where only the 5D0 ??7F1 transitions are allowed. Above this temperature the system undergoes a phase transition characterized by lack of inversion symmetry enabling the dipole-electric transitions.

8

Preparation, spectroscopy and morphology of Nd:YAG nanostructures

Hreniak D., Stręk W., Mazur P.

Materials Science

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2002

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Vol. 20, No. 2

39-45

EN

The neodymium-doped yttrium aluminum garnet (Nd:YAG) nanocrystalline powders were prepared by sol-gel method. The synthesis of semitransparent polycrystalline ceramics is described. Their structure and morphology were studied by means of XRD and TEM methods. It was found that with increasing thermal heating the size of Nd:YAG grains increase. Optical properties of Nd3+:YAG nanocrystalline powders and ceramics are reported. The evident influence of the grain size on the luminescence of Nd3+-ions has been observed.

9

Lu2O3:Eu, a new X-ray phosphor

Zych E., Hreniak D., Stręk W.

Materials Science

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2002

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Vol. 20, No. 1

111-122

EN

Five specimens of Lu2O3:5%Eu were prepared using various synthesis techniques. One of the samples was in the form of a plate, air-sintered at 1775 °C. Radio- and photoluminescence spectra were recorded showing emission exclusively from the 5D0 level of Eu3+. The most intense radioluminescence, about 30% of that from standard CsI:Tl, was seen from the sintered ceramic sample. Excitation spectra suggest that some aggregation of Eu3+ ions take place in four of the five specimens. Some contamination of the four powdered samples with OH groups was found. Only the sintered material showing the most powerful emission was free of this problem.