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THE APPLICATION OF NANOMATERIALS FOR LEAD FREE SOLDERS DEVELOPMENT
Pešina, Zbyněk ; Pinkas, Jiří (referee) ; Spousta, Jiří (referee) ; Sopoušek, Jiří (advisor)
The present dissertation is motivated by the search for alternatives of lead-free soldering by nanoparticles of metals and their alloys. The research focuses on the possibility of replacing lead-free solders by nanoparticles. This issue is currently being addressed by the use of lead-free solders but their properties are not entirely equivalent to properties of lead-tin based alloys. The theoretical part of the dissertation first summarizes up-to date knowledge on the development of lead-free alloys currently used for soldering in the electronics. The work compares these lead-free solder candidates with previously used Pb-Sn alloys. The second section of the theoretical part is devoted to nanotechnology that offers possible solutions of problems associated with the use of lead-free solders. The text contains a description of the properties of nanocrystalline materials in comparison with those of compact alloys having the same chemical composition. The possibility of preparation of nanoparticles and potential problems associated with small particle sizes are also presented. Introduction of the experimental part focuses on the preparation of nanoparticles of pure metals and alloys by chemical and physical ways as well as on an instrumentation for characterisation and analysis. Attention is focused on the silver in nanoparticle form that exhibits the low temperature sintering effect, which is thermally activated by decomposition of oxide envelope covering the Ag nanoparticles. This factor is critical for low-temperature sintering and thus also for possible future applications. The thermal effects of the low sintering process were studied by methods of thermal analysis. The preparation of the Cu / Ag nano / Cu joints was carried out in-situ in inert atmosphere and under the action of atmospheric oxygen. In both cases varying conditions of thermal treatment were used. The cross sections of the prepared joints were then used for the metallographic analysis of the local mechanical properties of the resulting silver layer, for the chemical composition evaluation of the resulting layers of the joint, and for the microstructure study. Strength characteristics are represented by testing shear strength of individual joints.
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Application of plasmonics in organic photovoltaics
Láska, Martin ; Fejfar, Antonín (referee) ; Šikola, Tomáš (advisor)
Tato diplomová práce se zabývá studiem plasmonicky navýšené absorpce vedoucí ke zlepšení účinnosti organických solárních článků. K navýšení absorpce světla ve fotoaktivní vrstvě jsou použity koloidní nanočástice stříbra. Rozptyl světla z nanočástic střibra do fotoaktivní vrstvy představuje jedno z možných řešení, jak navýšit celkovou účinnost fotovoltaických zařízení. Simulace elektromagnetických jevů jsou pro statické podmínky prováděny v softwaru Lumerical (Lumerical Solutions, Inc.). Je zkoumána absorpce ve fotoaktivní vrstvě v závislosti na konfiguraci stříbrných nanočástic. Simulace potvrzují, že ve fotoaktivní vrstvě, která je modifikovaná nanočásticemi stříbra, dochází k navýšení absorpce. Abychom potvrdili výsledky simulací, bylo vyrobeno několik stříbrem modifikovaných vzorků. Vzorky byly pro tento druh experimentu připravené z poly(3-hexyltiofenu):[6,6]-fenyl-C61-butyric-acid-metyl esteru. U některých, nanočásticemi stříbra modifikovaných, vzorků dochází k navýšení tvorby excitonů, v důsledku čehož je pozorován nárůst fotoproudu. V této práci je zahrnut teoretický i experimentální přístup k dané problematice.
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Biological synthesis of silver nanoparticles
Kubínová, Martina ; Španová, Alena (referee) ; Rittich, Bohuslav (advisor)
Silver nanoparticles and its potencial use and influence on the environment is still object of research. Methodics of synthesis of silver nanoparticles is already well investigated and study deals with more economical ways of syntesis by metireals, which are environmentally friendly and nontoxic. Biochemical production of nanoparticles has both advantages. This study focused on the production of nanoparticles by lactic acid bacteria and antibacterial activity. Experimental part of the study focused on amplification DNA isolated from Lactobacillus gasseri K7, which has efficiency to form silver nanoparticles. DNA was isolated in PCR, it was confirmed using primers specific for domena Bacteria and species Lactobacillus gasseri.
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Surface-enhanced resonance Raman scattering of Zn(II) porphyrins in systems with aggregated and non-aggregated Ag nanoparticles
Spáčil, Dušan ; Vlčková, Blanka (advisor) ; Procházka, Marek (referee)
In this diploma thesis, SERRS(Surface - enhanced resonance Raman Scattering) and SERS (Surface - enhanced Raman Scattering), surface of plasmon extinction spectra and TEM images of systems with tetracationic zinc porphyrin ZnTMPyP and silver nanoparticles (Ag NPs) were studied and interpreted. The systems with isolated nanoparticles and the systems with compact aggregates were investigated. The systems with isolated nanoparticles were prepared by addition of ZnTMPyP to hydrosol of Ag NPs. NaCl was added to this system and so compact aggregates were prepared. SERRS and SERS spectra of ZnTMPyP were studied at excitation wavelengths λexc= 441.6 nm a 532 nm. Firstly, stationary systems and secondly dynamic development of hydrosol Ag NPs → Ag NPs/ ZnTMPyP → Ag NPs/ ZnTMPyP/ NaCl systems for 680 s was investigated. Time evolution of SERRS and SERS spectra were analyzed by factor analysis (FA) and time evolution of spectra extinction plasmon were measured. FA showed a strong increase of the signal of ZnTMPyP after the addition of NaCl, i.e. after conversion of isolated nanoparticles to compact aggregates. In these systems with high concentration of ZnTMPyP the increase of signal was succeeded by its decreased. With help of FA the limit of SERRS spectral detection (λexc= 441,6 nm) and limit of SERS spectral...
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Photochromic effect in nanoporous titanium dioxide film with Ag nanocrystals
Galář, Pavel
The diploma thesis is devoted to multicolour photochromic effect in nanocomposite material Ag-TiO2, which is caused by a spectrally selective photoinduced decrease in extinction. The Thesis introduces briefly the theory of particle plasmons which are of fundamental significance for the investigated phenomenon. A short summary of the models and results published on photochromic effect in Ag-TiO2 is than given. The core of thesis deals with the optimization of this nanocomposite material towards a high photochromatic response. The influence of concentration of the TiO2 solution and of the speed of its spin coating deposition on a substrate was measured. Also the effect of AgNO3 quality used for sample preparation was monitored. A change in the extinction was found to depend on parameters of the excitation laser beam too. As a part of the optimization process, also the alternative TiO2 matrixes produced on basis of lamellar micelles were tested. The photochromic effect was monitored by measurements of the light extinction and scattering in dependence on the sample photoexposition. The properties of a set of the high-quality samples were studied using photoluminescence spectroscopy. Measurements of the photoluminescence decay with subpicosecond time resolution by up-conversion technique as well as of the...
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Surface-enhanced resonance Raman scattering of Zn(II) porphyrins in systems with aggregated and non-aggregated Ag nanoparticles
Spáčil, Dušan ; Vlčková, Blanka (advisor) ; Procházka, Marek (referee)
In this diploma thesis, SERRS(Surface - enhanced resonance Raman Scattering) and SERS (Surface - enhanced Raman Scattering), surface of plasmon extinction spectra and TEM images of systems with tetracationic zinc porphyrin ZnTMPyP and silver nanoparticles (Ag NPs) were studied and interpreted. The systems with isolated nanoparticles and the systems with compact aggregates were investigated. The systems with isolated nanoparticles were prepared by addition of ZnTMPyP to hydrosol of Ag NPs. NaCl was added to this system and so compact aggregates were prepared. SERRS and SERS spectra of ZnTMPyP were studied at excitation wavelengths λexc= 441.6 nm a 532 nm. Firstly, stationary systems and secondly dynamic development of hydrosol Ag NPs → Ag NPs/ ZnTMPyP → Ag NPs/ ZnTMPyP/ NaCl systems for 680 s was investigated. Time evolution of SERRS and SERS spectra were analyzed by factor analysis (FA) and time evolution of spectra extinction plasmon were measured. FA showed a strong increase of the signal of ZnTMPyP after the addition of NaCl, i.e. after conversion of isolated nanoparticles to compact aggregates. In these systems with high concentration of ZnTMPyP the increase of signal was succeeded by its decreased. With help of FA the limit of SERRS spectral detection (λexc= 441,6 nm) and limit of SERS spectral...
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Photochromic effect in nanoporous titanium dioxide film with Ag nanocrystals
Galář, Pavel
The diploma thesis is devoted to multicolour photochromic effect in nanocomposite material Ag-TiO2, which is caused by a spectrally selective photoinduced decrease in extinction. The Thesis introduces briefly the theory of particle plasmons which are of fundamental significance for the investigated phenomenon. A short summary of the models and results published on photochromic effect in Ag-TiO2 is than given. The core of thesis deals with the optimization of this nanocomposite material towards a high photochromatic response. The influence of concentration of the TiO2 solution and of the speed of its spin coating deposition on a substrate was measured. Also the effect of AgNO3 quality used for sample preparation was monitored. A change in the extinction was found to depend on parameters of the excitation laser beam too. As a part of the optimization process, also the alternative TiO2 matrixes produced on basis of lamellar micelles were tested. The photochromic effect was monitored by measurements of the light extinction and scattering in dependence on the sample photoexposition. The properties of a set of the high-quality samples were studied using photoluminescence spectroscopy. Measurements of the photoluminescence decay with subpicosecond time resolution by up-conversion technique as well as of the...
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Biological synthesis of silver nanoparticles
Kubínová, Martina ; Španová, Alena (referee) ; Rittich, Bohuslav (advisor)
Silver nanoparticles and its potencial use and influence on the environment is still object of research. Methodics of synthesis of silver nanoparticles is already well investigated and study deals with more economical ways of syntesis by metireals, which are environmentally friendly and nontoxic. Biochemical production of nanoparticles has both advantages. This study focused on the production of nanoparticles by lactic acid bacteria and antibacterial activity. Experimental part of the study focused on amplification DNA isolated from Lactobacillus gasseri K7, which has efficiency to form silver nanoparticles. DNA was isolated in PCR, it was confirmed using primers specific for domena Bacteria and species Lactobacillus gasseri.
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THE APPLICATION OF NANOMATERIALS FOR LEAD FREE SOLDERS DEVELOPMENT
Pešina, Zbyněk ; Pinkas, Jiří (referee) ; Spousta, Jiří (referee) ; Sopoušek, Jiří (advisor)
The present dissertation is motivated by the search for alternatives of lead-free soldering by nanoparticles of metals and their alloys. The research focuses on the possibility of replacing lead-free solders by nanoparticles. This issue is currently being addressed by the use of lead-free solders but their properties are not entirely equivalent to properties of lead-tin based alloys. The theoretical part of the dissertation first summarizes up-to date knowledge on the development of lead-free alloys currently used for soldering in the electronics. The work compares these lead-free solder candidates with previously used Pb-Sn alloys. The second section of the theoretical part is devoted to nanotechnology that offers possible solutions of problems associated with the use of lead-free solders. The text contains a description of the properties of nanocrystalline materials in comparison with those of compact alloys having the same chemical composition. The possibility of preparation of nanoparticles and potential problems associated with small particle sizes are also presented. Introduction of the experimental part focuses on the preparation of nanoparticles of pure metals and alloys by chemical and physical ways as well as on an instrumentation for characterisation and analysis. Attention is focused on the silver in nanoparticle form that exhibits the low temperature sintering effect, which is thermally activated by decomposition of oxide envelope covering the Ag nanoparticles. This factor is critical for low-temperature sintering and thus also for possible future applications. The thermal effects of the low sintering process were studied by methods of thermal analysis. The preparation of the Cu / Ag nano / Cu joints was carried out in-situ in inert atmosphere and under the action of atmospheric oxygen. In both cases varying conditions of thermal treatment were used. The cross sections of the prepared joints were then used for the metallographic analysis of the local mechanical properties of the resulting silver layer, for the chemical composition evaluation of the resulting layers of the joint, and for the microstructure study. Strength characteristics are represented by testing shear strength of individual joints.
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Application of plasmonics in organic photovoltaics
Láska, Martin ; Fejfar, Antonín (referee) ; Šikola, Tomáš (advisor)
Tato diplomová práce se zabývá studiem plasmonicky navýšené absorpce vedoucí ke zlepšení účinnosti organických solárních článků. K navýšení absorpce světla ve fotoaktivní vrstvě jsou použity koloidní nanočástice stříbra. Rozptyl světla z nanočástic střibra do fotoaktivní vrstvy představuje jedno z možných řešení, jak navýšit celkovou účinnost fotovoltaických zařízení. Simulace elektromagnetických jevů jsou pro statické podmínky prováděny v softwaru Lumerical (Lumerical Solutions, Inc.). Je zkoumána absorpce ve fotoaktivní vrstvě v závislosti na konfiguraci stříbrných nanočástic. Simulace potvrzují, že ve fotoaktivní vrstvě, která je modifikovaná nanočásticemi stříbra, dochází k navýšení absorpce. Abychom potvrdili výsledky simulací, bylo vyrobeno několik stříbrem modifikovaných vzorků. Vzorky byly pro tento druh experimentu připravené z poly(3-hexyltiofenu):[6,6]-fenyl-C61-butyric-acid-metyl esteru. U některých, nanočásticemi stříbra modifikovaných, vzorků dochází k navýšení tvorby excitonů, v důsledku čehož je pozorován nárůst fotoproudu. V této práci je zahrnut teoretický i experimentální přístup k dané problematice.
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