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Papers by Lenka Prochazkova

Research paper thumbnail of Core–shell ZnO:Ga-SiO<sub>2</sub> nanocrystals: limiting particle agglomeration and increasing luminescence <i>via</i> surface defect passivation

Research paper thumbnail of YAG Ceramic Nanocrystals Implementation into MCVD Technology of Active Optical Fibers

Applied Sciences, 2018

Nanoparticle doping is an alternative approach the conventional solution doping method allowing t... more Nanoparticle doping is an alternative approach the conventional solution doping method allowing the preparation of active optical fibers with improved optical and structural properties. The combination of the nanoparticle doping with MCVD process has brought new technological challenges. We present the preparation of fiber lasers doped with Er-doped yttrium aluminum garnet (Er:YAG) nanocrystals. These nanocrystals, prepared by a hydrothermal reaction, were analyzed by several structural methods to determine the mean nanocrystal size and an effective hydrodynamic radius. The nanocrystals were incorporated into silica frits with various porosity made by the conventional MCVD process. The Er:YAG-doped silica frits were processed into preforms, which were drawn into optical fibers. We studied the effect of the nanocrystal size and frit's porosity on the final structural and optical properties of prepared preforms and optical fibers. Selected optical fibers were tested as an active medium in a fiber ring laser setup and the characteristics of the laser were determined. Optimal laser properties were achieved for the fiber length of 7 m. The slope efficiency of the fiber laser was about 42%. Presented method can be simply extended to the deposition of other ceramic nanomaterials.

Research paper thumbnail of {"__content__"=>"LuAG:Pr-porphyrin based nanohybrid system for singlet oxygen production: Toward the next generation of PDTX drugs.", "sup"=>{"__content__"=>"3+"}}

Journal of photochemistry and photobiology. B, Biology, 2018

A highly prospective drug for the X-ray induced photodynamic therapy (PDTX), LuAG:Pr@SiO-PpIX nan... more A highly prospective drug for the X-ray induced photodynamic therapy (PDTX), LuAG:Pr@SiO-PpIX nanocomposite, was successfully prepared by a three step process: photo-induced precipitation of the LuAlO:Pr (LuAG:Pr) core, sol-gel technique for amorphous silica coating, and a biofunctionalization by attaching the protoporphyrin IX (PpIX) molecules. The synthesis procedure provides three-layer nanocomposite with uniform shells covering an intensely luminescent core. Room temperature radioluminescence (RT RL) spectra as well as photoluminescence (RT PL) steady-state and time resolved spectra of the material confirm the non-radiative energy transfer from the core Pr ions to the PpIX outer layer. First, excitation of Pr ions results in the red luminescence of PpIX. Second, the decay measurements exhibit clear evidence of mentioned non-radiative energy transfer (ET). The singlet oxygen generation in the system was demonstrated by the 3'-(p-aminophenyl) fluorescein (APF) chemical probe s...

Research paper thumbnail of Preliminary study on singlet oxygen production using CeF3:Tb3+@SiO2-PpIX

Radiation Measurements, 2016

h i g h l i g h t s CeF 3 :Tb 3þ nanoparticles were prepared via solegel route. Surface modificat... more h i g h l i g h t s CeF 3 :Tb 3þ nanoparticles were prepared via solegel route. Surface modification by SiO 2 layer and bioconjugation with PpIX were performed. Radioluminescence spectra indicate an energy transfer from Tb 3þ to PpIX. X-ray-induced singlet oxygen production was observed.

Research paper thumbnail of Active Optical Fibers Doped with Ceramic Nanocrystals

Advances in Electrical and Electronic Engineering, 2015

Erbium-doped active optical fiber was successfully prepared by incorporation of ceramic nanocryst... more Erbium-doped active optical fiber was successfully prepared by incorporation of ceramic nanocrystals inside a core of optical fiber. Modified chemical vapor deposition was combined with solutiondoping approach to preparing preform. Instead of inorganic salts erbium-doped yttrium-aluminium garnet nanocrystals were used in the solution-doping process. Prepared preform was drawn into single-mode optical fiber with a numerical aperture 0.167. Optical and luminescence properties of the fiber were analyzed. Lasing ability of prepared fiber was proofed in a fiber-ring setup. Optimal laser properties were achieved for a fiber length of 20 m. The slope efficiency of the fiberlaser was about 15 %. Presented method can be simply extended to the deposition of other ceramic nanomaterials.

Research paper thumbnail of Photo and radiation induced synthesis of (Ni, Zn)O or mixed NiO–ZnO oxides

Journal of Radioanalytical and Nuclear Chemistry, 2014

A set of mixed oxide samples containing crystalline NiO-ZnO with variable composition was prepare... more A set of mixed oxide samples containing crystalline NiO-ZnO with variable composition was prepared by irradiation of aqueous solutions containing nickel and/or zinc nitrate hexahydrate, with subsequent heat treatment. Due to irradiation, either by accelerated electrons or UV light, weakly crystalline solid precursor was formed. After heat treatment at temperatures of 300°C or higher, nanocrystalline NiO, ZnO and mixture of ZnO and solid solution (Ni, Zn)O were formed, with different amounts of nickel or zinc. Photo or radiation induced synthesis yielded material with quality nanocrystals (from one to twenty nm) and very high specific surface area.

Research paper thumbnail of UV radiation: a promising tool in the synthesis of multicomponent nano-oxides

Journal of Nanoparticle Research, 2014

ABSTRACT Photochemical synthesis of selected multicomponent compounds, namely cadmium or magnesiu... more ABSTRACT Photochemical synthesis of selected multicomponent compounds, namely cadmium or magnesium zinc oxides doped with Ga3+ ions—Zn1−x Cd x (Mg x )O:Ga—and lutetium aluminum garnets Lu3Al5O12 (LuAG) doped with Pr3+ or Eu3+ ions (LuAG:Pr(Eu)), was successfully performed. The synthesis is based on photo-induced precipitation of solid precursors from aqueous solutions containing formate anion and soluble metal salts (nitrates or chlorides). Low pressure mercury lamps were used for the irradiation of solutions. Solid precursors were subsequently separated from aqueous phase and calcined to obtain the final products. Prepared materials feature high chemical purity, good crystallinity, and nano-dimensions in the range of 10–100 nm. Due to the high level of interaction among individual components in photo-precipitated precursors, no additional oxide phases were observed after calcination apart from the desired solid phase. Moreover, highly intensive radioluminescence or shift of excitonic luminescence has been observed, depending on type and composition of prepared materials. Results indicate that prepared nanomaterials may be prospectively utilized as highly efficient nanoscintillators for preparation of optical ceramics or band-gap engineered nanophosphors.

Research paper thumbnail of CsPbBr3 Thin Films on LYSO:Ce Substrates

IEEE Transactions on Nuclear Science, 2020

We fabricate thin films of lead halide perovskite nanocrystals on glass substrates and cerium-dop... more We fabricate thin films of lead halide perovskite nanocrystals on glass substrates and cerium-doped LYSO substrates (lutetium-yttrium oxyorthosilicate, LuxY2-xSiO5:Ce) using spin-coating and drop-casting methods, respectively. We study their structural and optical properties. The luminescence and scintillation are monitored in both steady-state and time-resolved regimes. We focus on the possibility to exploit these structures in designing a detection system with ultrafast time resolution.

Research paper thumbnail of Core–shell ZnO:Ga-SiO<sub>2</sub> nanocrystals: limiting particle agglomeration and increasing luminescence <i>via</i> surface defect passivation

Research paper thumbnail of YAG Ceramic Nanocrystals Implementation into MCVD Technology of Active Optical Fibers

Applied Sciences, 2018

Nanoparticle doping is an alternative approach the conventional solution doping method allowing t... more Nanoparticle doping is an alternative approach the conventional solution doping method allowing the preparation of active optical fibers with improved optical and structural properties. The combination of the nanoparticle doping with MCVD process has brought new technological challenges. We present the preparation of fiber lasers doped with Er-doped yttrium aluminum garnet (Er:YAG) nanocrystals. These nanocrystals, prepared by a hydrothermal reaction, were analyzed by several structural methods to determine the mean nanocrystal size and an effective hydrodynamic radius. The nanocrystals were incorporated into silica frits with various porosity made by the conventional MCVD process. The Er:YAG-doped silica frits were processed into preforms, which were drawn into optical fibers. We studied the effect of the nanocrystal size and frit's porosity on the final structural and optical properties of prepared preforms and optical fibers. Selected optical fibers were tested as an active medium in a fiber ring laser setup and the characteristics of the laser were determined. Optimal laser properties were achieved for the fiber length of 7 m. The slope efficiency of the fiber laser was about 42%. Presented method can be simply extended to the deposition of other ceramic nanomaterials.

Research paper thumbnail of {"__content__"=>"LuAG:Pr-porphyrin based nanohybrid system for singlet oxygen production: Toward the next generation of PDTX drugs.", "sup"=>{"__content__"=>"3+"}}

Journal of photochemistry and photobiology. B, Biology, 2018

A highly prospective drug for the X-ray induced photodynamic therapy (PDTX), LuAG:Pr@SiO-PpIX nan... more A highly prospective drug for the X-ray induced photodynamic therapy (PDTX), LuAG:Pr@SiO-PpIX nanocomposite, was successfully prepared by a three step process: photo-induced precipitation of the LuAlO:Pr (LuAG:Pr) core, sol-gel technique for amorphous silica coating, and a biofunctionalization by attaching the protoporphyrin IX (PpIX) molecules. The synthesis procedure provides three-layer nanocomposite with uniform shells covering an intensely luminescent core. Room temperature radioluminescence (RT RL) spectra as well as photoluminescence (RT PL) steady-state and time resolved spectra of the material confirm the non-radiative energy transfer from the core Pr ions to the PpIX outer layer. First, excitation of Pr ions results in the red luminescence of PpIX. Second, the decay measurements exhibit clear evidence of mentioned non-radiative energy transfer (ET). The singlet oxygen generation in the system was demonstrated by the 3'-(p-aminophenyl) fluorescein (APF) chemical probe s...

Research paper thumbnail of Preliminary study on singlet oxygen production using CeF3:Tb3+@SiO2-PpIX

Radiation Measurements, 2016

h i g h l i g h t s CeF 3 :Tb 3þ nanoparticles were prepared via solegel route. Surface modificat... more h i g h l i g h t s CeF 3 :Tb 3þ nanoparticles were prepared via solegel route. Surface modification by SiO 2 layer and bioconjugation with PpIX were performed. Radioluminescence spectra indicate an energy transfer from Tb 3þ to PpIX. X-ray-induced singlet oxygen production was observed.

Research paper thumbnail of Active Optical Fibers Doped with Ceramic Nanocrystals

Advances in Electrical and Electronic Engineering, 2015

Erbium-doped active optical fiber was successfully prepared by incorporation of ceramic nanocryst... more Erbium-doped active optical fiber was successfully prepared by incorporation of ceramic nanocrystals inside a core of optical fiber. Modified chemical vapor deposition was combined with solutiondoping approach to preparing preform. Instead of inorganic salts erbium-doped yttrium-aluminium garnet nanocrystals were used in the solution-doping process. Prepared preform was drawn into single-mode optical fiber with a numerical aperture 0.167. Optical and luminescence properties of the fiber were analyzed. Lasing ability of prepared fiber was proofed in a fiber-ring setup. Optimal laser properties were achieved for a fiber length of 20 m. The slope efficiency of the fiberlaser was about 15 %. Presented method can be simply extended to the deposition of other ceramic nanomaterials.

Research paper thumbnail of Photo and radiation induced synthesis of (Ni, Zn)O or mixed NiO–ZnO oxides

Journal of Radioanalytical and Nuclear Chemistry, 2014

A set of mixed oxide samples containing crystalline NiO-ZnO with variable composition was prepare... more A set of mixed oxide samples containing crystalline NiO-ZnO with variable composition was prepared by irradiation of aqueous solutions containing nickel and/or zinc nitrate hexahydrate, with subsequent heat treatment. Due to irradiation, either by accelerated electrons or UV light, weakly crystalline solid precursor was formed. After heat treatment at temperatures of 300°C or higher, nanocrystalline NiO, ZnO and mixture of ZnO and solid solution (Ni, Zn)O were formed, with different amounts of nickel or zinc. Photo or radiation induced synthesis yielded material with quality nanocrystals (from one to twenty nm) and very high specific surface area.

Research paper thumbnail of UV radiation: a promising tool in the synthesis of multicomponent nano-oxides

Journal of Nanoparticle Research, 2014

ABSTRACT Photochemical synthesis of selected multicomponent compounds, namely cadmium or magnesiu... more ABSTRACT Photochemical synthesis of selected multicomponent compounds, namely cadmium or magnesium zinc oxides doped with Ga3+ ions—Zn1−x Cd x (Mg x )O:Ga—and lutetium aluminum garnets Lu3Al5O12 (LuAG) doped with Pr3+ or Eu3+ ions (LuAG:Pr(Eu)), was successfully performed. The synthesis is based on photo-induced precipitation of solid precursors from aqueous solutions containing formate anion and soluble metal salts (nitrates or chlorides). Low pressure mercury lamps were used for the irradiation of solutions. Solid precursors were subsequently separated from aqueous phase and calcined to obtain the final products. Prepared materials feature high chemical purity, good crystallinity, and nano-dimensions in the range of 10–100 nm. Due to the high level of interaction among individual components in photo-precipitated precursors, no additional oxide phases were observed after calcination apart from the desired solid phase. Moreover, highly intensive radioluminescence or shift of excitonic luminescence has been observed, depending on type and composition of prepared materials. Results indicate that prepared nanomaterials may be prospectively utilized as highly efficient nanoscintillators for preparation of optical ceramics or band-gap engineered nanophosphors.

Research paper thumbnail of CsPbBr3 Thin Films on LYSO:Ce Substrates

IEEE Transactions on Nuclear Science, 2020

We fabricate thin films of lead halide perovskite nanocrystals on glass substrates and cerium-dop... more We fabricate thin films of lead halide perovskite nanocrystals on glass substrates and cerium-doped LYSO substrates (lutetium-yttrium oxyorthosilicate, LuxY2-xSiO5:Ce) using spin-coating and drop-casting methods, respectively. We study their structural and optical properties. The luminescence and scintillation are monitored in both steady-state and time-resolved regimes. We focus on the possibility to exploit these structures in designing a detection system with ultrafast time resolution.