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1

Effect of Cd precursor on structure and optical properties of spin coated Zn0.9Cd0.1O films for optoelectronics applications

Arora Isha, Kumar Praveen, Sathiaraj T. S.

Materials Science Poland

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2020

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Vol. 38, No. 3

459--464

EN

The development of transparent conducting oxide materials has gained an increased interest in the scientific community for developing efficient low cost optoelectronic devices. The effect of Cd precursor on structural and optical properties of sol-gel synthesized Zn0.9Cd0.1O nanostructured films has been studied by using XRD, AFM, optical absorption and emission spectroscopic techniques. X-ray diffraction confirms the hexagonal wurtzite crystal structure of the deposited films and the relative intensity of diffraction peaks has been observed with different cadmium salts. The granular surface morphology of the synthesized films has been observed from AFM measurements. The optical transmission, band gap and luminescence intensity was found to change for different cadmium salts. These results are very important for developing new materials for optoelectronic applications.

2

Morphological, chemical and structural characterization of silica-containing polyvinylpyrrolidone electrospun nanofibers prepared by sol-gel technique

Tański T., Matysiak W., Zaborowska M., Łukowiec D., Krzesiński M.

Journal of Achievements in Materials and Manufacturing Engineering

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2016

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Vol. 79, nr 1

5--12

EN

Purpose: The aim of this study was to produce poly(vinylpyrrolidone) (PVP) containing silica nanofibers using electrospinning method from 10% PVP/EtOH solutions with different mass concentration 0 and 30% of tetraethoxysilane. Sol-gel technique was used to obtain nanofiber membranes with high amount of inorganic phase. In the case when metal alkoxide, such as tetraethyl orthosilicate (TEOS) is mixed with an organic polymer, hydrolysis and condensation reaction of TEOS occur in-situ with polymer matrix, which allows to fabricate organic-inorganic hybrid structures with uniform dispersion. Design/methodology/approach: The examination of the morphology of the obtained PVP/silicon dioxide nanofibers using scanning electron microscope (SEM) has been made. The chemical structure of produced nanostructures was investigated by Fourier - Transform Infrared spectroscopy (FTIR) and Energy Dispersive Spectrometry (EDX) to analyze the regular dispersion by examining types of bonds occurring between polymer matrix and SiO2 phase. Findings: Results obtained in this paper shows that the mass concentration of the reinforcing phase in form of TEOS have an influence on the average diameter of nanofibers and with the increase of tetraethyl orthosilicate in solution nanofibers diameters decrease. Moreover, structural examination shows uniform dispersion of the reinforcing phase in hybrid materials. Research limitations/implications: Uniform dispersion of the reinforcing phase in silica-containing PVP nanofibers gives the opportunity to make nanowires in calcination process from such obtained fibrous mats and use in novel electrical devices. Originality/value: This paper describes an easy and more effective way of making polymer nanofibers with the content of silicon dioxide with the perspective way of making silica nanowires in the future from obtained hybrid nanofibers, so that this method can replace commonly used nanowires growth processes.

3

Fabrication and characterization of compositionally graded Bi1−x Gd x FeO3 thin films

Chen C. C., Liu Z X, Wang G., Feng X D

Materials Science Poland

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2014

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Vol. 32, No. 3

498--502

EN

An undoped BiFeO3 thin film, Gd doped Bi0.95Gd0.05FeO3 thin film with a constant composition, Gd up-graded doped Bi1−x Gd x FeO3 and Gd down-graded doped Bi1−x Gd x FeO3 thin films were successfully grown on Pt (111)/Ti/SiO2/Si (100) substrates using a sol-gel and spin coating technique. The crystal structure, ferroelectric and dielectric characteristics as well as the leakage currents of these samples were thoroughly investigated. The XRD (X-Ray Diffraction) patterns indicate that all these thin films consist of solely perovskite phase with polycrystalline structure. No other secondary phases have been detected. Clear polarization-electric field (P-E) hysteresis loops of all these thin films demonstrate that the incorporation of Gd3+ into the Bi site of BFO thin film have enhanced the ferroelectric performance of pure BiFeO3 thin film, and the Gd down-graded doped Bi1−x Gd x FeO3 thin film has the best ferroelectric properties. Compared to other thin films, the optimal ferroelectric behavior of the Gd down-graded doped Bi1−x Gd x FeO3 thin film results from its large dielectric constant, low dissipation factor and low leakage current.

4

Porosity structure in photon active glasses

Jasińska B., Śniegocka M., Reisfeld R., Zigansky E.

Nukleonika

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2013

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Vol. 58, No. 1

241-244

EN

Two kinds of photon active glasses were investigated using positron annihilation lifetime spectroscopy (PALS). Both kinds of glasses were prepared using a sol-gel technique, doped by complex of ruthenium tris bipyridyl chloride. Glasses differed from the initial matrix: the first one was prepared using silicon oxide while the second one - zircon oxide. The ortho-positronium (o-Ps) lifetime and intensities were determined from lifetime spectra. Different porosity structure concluded from PALS measurements was found in both cases. In the silica based glasses small free volumes (angstrom size) and pores (from 1 to 10 nm) existed in the material. On the contrary, in zirconia based glasses small intermolecular voids were produced in the structure only, independently of the way of material preparation.

5

Sol-gel-derived inorganic-organic hybrid polymers filled with ZnO nanoparticles as an ultraviolet protection finish for textiles

Farouk A., Textor T., Schollmeyer E., Tarbuk A., Grancacic A. M.

Autex Research Journal

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2010

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Vol. 10, no. 3

58--63

EN

Despite the beneficial effects of ultraviolet (UV) radiation on the skin, radiation can cause sunburn, skin aging, allergies and even skin cancer. Textiles can provide effective protection against such damage. Unlike cosmetics, using textiles to protect the skin has only recently been researched. The design and modification of fabrics leading to a high protection against UV radiation is a relatively new application. It is important to consider the kinds of textiles to be used because most of the garments worn during summer, the time of highest exposure, are light and colourless materials that provide the lowest protection. Here, we report the synthesis and characterisation of nanosized zinc oxide particles known to absorb UV light. Sol-gel-based inorganic-organic hybrid polymers were modified with these particles and applied to cellulosic cotton (100%) and cotton/polyester (65/35%) fabrics. These modified inorganic-organic hybrids polymers were based on 3-GPTMS. The complete finishing sol prepared in this work has a marked long stability. The effectiveness of the novel finishing was determined by UV-visible spectroscopy to evaluate the UV protection factor. The influences of the finishing for general textile properties such as tensile strength, elongation, air permeability, degree of whiteness, wear resistance, stiffness and the durability of the treatments were investigated.

6

Synteza, właściwości optyczne i elektryczne nanokrystalicznych materiałów BaTiO_3 domieszkowanych jonami ziem rzadkich

Pązik R., Stręk W., Nitsch K.

Wiadomości Chemiczne

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2009

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[Z] 63, 9-10

878-931

EN

The main goals of the presented paper were focused on synthesis of nanocrystalline BaTiO^3 materials doped with chosen rare earth ions (Eu^3+ and Yb^3+) utilizing sol-gel technique. Structure, morphology, optical and electrical properties were characterized. Size effects and their influence on the mentioned physicochemical properties were discussed. Strong effect of the dopant concentration on the structure of BaTiO_3 was found. In case of the Eu3+ ions doping results in stabilization of tetragonal phase of BaTiO^3 whereas addition of the Yb^3+ ions favors formation of the cubic structure. Besides that all introduced ions could be considered as inhibitors for the grain growth process. Moreover resulted powders showed co-existence of the tetragonal (ferroelectric) and cubic (paraelectric) phases. The amount of the tetragonal phase depends on the heat treatment temperature and concentration of the incorporated rare earth ions. The structural changes of a matrix were studied using the Eu^3+ and Yb^3+ ions as optical probes. Their luminescence properties were dependent on the sintering temperature. In case of the Eu^3+ ions we have found that the intensities of D→7F transitions increased with the increasing temperature. It means higher Eu3+ ions symmetry associates with higher temperature [1–4]. On the other hand in nano-crystals doped with Yb3+ ions a higher intensity of SHG (second harmonic generation) was observed in the tetragonal phase, whereas the isotropic cubic phase was detected by the absence of a SHG signal. Cooperative emission, indicating the presence of Yb3+ ion pairs, was easily detected in the cubic phase and not seen in the ferroelectric tetragonal structure [5]. BaTiO_3 nanoceramics were fabricated from the nanopowders using LTHP (low-temperature high pressure) sintering process [6, 7]. The impedance spectra indicated the complex nature of the effects appearing in the analyzed BaTiO3 nanoceramics. Four types of physical mechanisms contributing to the overall conductivity were found, namely hopping, diffusion, two relaxation mechanisms and the dc conduction. The studied samples show a ferroelectric-paralelectric phase transition observed for the higher frequency regions.

7

Sol-gel derived inorganic-organic hybrid polymers filled with ZnO nanoparticles as ultraviolet protection finish for textiles

Farouk A., Textor T, Schollmeyer E., Tarbuk A., Grancacic A. M

Autex Research Journal

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2009

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Vol. 9, no. 4

114--120

EN

In spite of some beneficial effects of ultraviolet (UV) radiation on skin, radiation can cause sunburn, skin aging, allergies and even skin cancer. Textiles can provide effective protection against such damage of UV radiation. Unlike cosmetics, using textiles protecting the skin or at least enhancing protection has only recently been researched. The design and modification of fabrics leading to a high protection against UV radiation is a relatively new application. It is very important to consider the kind of textile to be used, most of the garments worn during summer, the time of highest exposition, are light and colourless materials and therefore provide the lowest protection. We report the synthesis and characterization of nanosized zinc oxide particles known to highly absorb UV light. Sol-gel based inorganic-organic hybrid polymers were modified with these particles and were applied to cellulosic cotton (100%) and cotton/polyester (65/35%) fabrics. These modified inorganicorganic hybrids polymers were based on 3-glycidyloxypropyltrimethoxysilane (GPTMS). Complete finishing sol prepared in this work has remarked long stability for further processing. The effectiveness of the novel finishing was determined by UV-Vis spectroscopy and by evaluation of the ultraviolet protection factor (UPF). The influences of the finishing for some general textile properties as e.g. tensile strength, elongation, air permeability, degree of whiteness, wear-resistance, stiffness as well as the durability of the treatments were investigated.

8

Copolymerization of ethylene with 1-hexene over vanadium catalysts immobilized on sol-gel silica

Białek M., Korach Ł., Czaja K.

Polimery

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2007

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T. 52, nr 11-12

889-892

EN

Silica-type materials with different structure and morphology, synthesized using sol-gel process, were applied as a carriers of organometallic catalytic systems (VOCl3/AlEt2Cl) for ethylene-1-hexene copolymerization. Carrier materials, prior to immobilization of the vanadium compound, were pre-treated using two modes: one-step thermal modification and two-steps modification including additional reaction with AlEt2Cl. It was found that the carrier's type and way of it's modification significantly influence the catalysts activity in ethylene-1-hexene copolymerization as well as the incorporation of higher 1-olefin. The favourable effect of two-step modification mode on the catalysts activity and 1-hexene incorporation efficiency was proposed.

PL

Proszki krzemionkowe o zróżnicowanej morfologii i charakterze chemicznym powierzchni, otrzymane techniką zol-żelową, stosowano jako nośniki metaloorganicznych katalizatorów wanadowych (VOCl3/AlEt2Cl) do niskociśnieniowej kopolimeryzacji etylenu z 1-heksenem. Nośniki, przed zakotwiczeniem związku metalu przejściowego, poddawano jedno lub dwustopniowej modyfikacji, polegającej na wygrzewaniu w temp. 200°C wraz z ewentualnym dodatkowym działaniem AlEt2Cl. Stwierdzono, że typ zastosowanego nośnika układu katalitycznego oraz sposób jego modyfikacji znacząco wpływają na aktywność zarówno w procesie homopolimeryzacji etylenu jak i jego kopolimeryzacji z 1-heksenem. Szczególnie aktywnym i efektywnym w odniesieniu do zdolności wbudowania 1-olefiny w łańcuch polietylenu okazał się układ zakotwiczony na nośniku posiadającym powierzchniowe grupy metylowe, poddanym dodatkowo modyfikacji związkiem glinoorganicznym. Zaproponowany mechanizm korzystnego działania dwustopniowej modyfikacji polega najprawdopodobniej na pełnieniu przez wprowadzony związek glinoorganiczny roli "łącznika" odseparowującego centra aktywne od powierzchni nośnika, a tym samym wpływającego na zwiększenie ich dostępności dla cząsteczek monomeru, co jest szczególnie istotne w przypadku wyższej olefiny.

9

Sol-gel nanomaterials

Maruszewski K.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2006

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Vol. 43, nr 17

34-48

EN

Conventional glass preparation requires melting of the precursors at high temperatures, rapid cooling and subsequent vitrification of the glassy material. This procedure highly restricts choice of substances which can be entrapped in the glass products. Basically only metal oxides and some inorganic salts can survive such drastic conditions avoiding thermal decomposition. Furthermore, the way in which conventional glass is produced makes thin films preparation extremely cumbersome and the only method of preparation of porous classical glasses requires etching or partial dissolving (e.g. VycorŽ glass). On the other hand glass and glassy materials possess several useful features for optical applications such as transparency, homogeneity, mechanical sturdiness, high refractive index etc. An alternative approach to glass and glass-like materials is offered by the, so called, sol-gel technology. The process itself is known for more than a century [1], but it has gained a new importance in the last two decades after pioneering results of Dislich [2]. He and other researchers improved the chemistry of the process so much that it is now possible to obtain samples in days (or even hours - in case of thin films) rather than months (or years) like in the case of the early samples [1]. The sol-gel technique is based on hydrolysis of liquid precursors and formation of colloidal sols. The precursors are usually organosilicates (e.g. TEOS -tetraethoxysilane) yielding silicate sol-gel materials.

10

Photosensitized oxidation as a tool for degradation of harmful substances in water solutions

Gryglik D., Miller J.S.

Chemia i Inżynieria Ekologiczna

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2005

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Vol. 12, nr 9

977-987

EN

The applicability of photochemical process involving singlet molecular oxygen (102) in the field of environmental protection was considered. 102 was generated via energy transfer from dye sensitizer excited by visible light to ground stale oxygen (302). The photosensitized oxidation was applied for degradation of 2-chlorophenol (2-CP), a common model organic pollutant, and ingredient of many pesticides. The 2-CP decomposition in, an aqueous solution was studied using various sensitizers in two types of reactions: in the homogeneous system with a solubilized sensitizer and in the heterogeneous system with a sensitizer immobilized in silane gel covering the glass reactor walls. In both systems the influence of various experimental conditions (light intensity, the amount of sensitizer, oxygen concentration) on the rate of 2-CP degradation was investigated. Finally, the possibility of using sunlight for decomposition of 2-CP in aqueous solutions both in homo- and heterogeneous system was demonstrated.

PL

Badano sensybilizowane fotoutleniania, pod kątem rozpoznania możliwości jego zastosowania do degradacji szkodliwych zanieczyszczeń w środowisku wodnym. W procesie zastosowano różne sensybilizatory w postaci roztworu oraz immobilizowane w żelu silanowym na szklanym podłożu. Efektywność procesu określano przez szybkość rozkładu 2-chlorofenolu w różnych warunkach natlenienia i naświetlania roztworu reakcyjnego. Sprawdzono również możliwość degradacji 2-chlorofenolu w procesie sensybilizowanego utleniania pod działaniem promieniowania słonecznego.

11

Silica powder obtained by sol-gel method as a support of organometallic vanadium catalyst for ethylene polymerization

Korach Ł., Czaja K., Kovaleva N.Yu.

Polimery

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2004

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T. 49, nr 9

641--645

EN

Sol-gel technique was employed to obtain the silica-type powder, which after modification procedure was applied as a support of organometallic catalytic system for ethylene polymerization. The powder product was synthesized using hydrolysis and condensation of TEOS, catalyzed by ammonia. Obtained material and a reference support (commercial' silica Davisil) were characterized to determine their particle size distributions, BET surface area, pore volume and diameter. Gas-phase adsorption of vanadium catalyst on analyzed support materials as well as adsorption from the solution in hexane were carried out. Both carrier materials were thermally pretreated prior catalytic systems syntheses and the influence of modification method applied on resulting organometallic catalyst character was estimated in low-pressure slurry polymerization of ethylene. Obtained results prove that sol--gel material, due to its advantageous morphology with wide and shallow pores, allows to obtain catalytic systems of higher activity in low-pressure ethylene polymerization, in comparison with commercial silica Davisil.

PL

Techniką zol-żel otrzymano materiały typu krzemionkowego, które po wygrzewaniu w temp. 200 °C lub 800 °C stosowano w charakterze nośnika wymienionego w tytule katalizatora. Zastosowana procedura zol-żel polegała na katalizowanej amoniakiem hydrolizie i kondensacji tetraetoksysilanu (TEOS). Tak otrzymane materiały proszkowe oraz, dla porównania, komercyjną krzemionkę "Davisil" (również wygrzewaną w podanej uprzednio temperaturze) scharakteryzowano pod kątem rozkładu wymiarów ziaren, powierzchni właściwej oraz struktury porowatej (tabela 1, rys. 1 i 2). Przeprowadzono badania adsorpcji na tych nośnikach VOCl3 zarówno z fazy gazowej, jak i roztworu w heksanie (tabela 1). Stwierdzono, że proszek otrzymany według procedury zol-żel pozwala na otrzymanie wanadowych układów katalitycznych aktywniejszych w procesie polimeryzacji w porównaniu z ich odpowiednikami zakotwiczonymi na komercyjnej krzemionce (tabela 1). Czynnikiem decydującym o szczególnej przydatności krzemionki otrzymanej metodą zol-żel jako nośnika katalizatora jest najprawdopodobniej obecność na jej powierzchni płytkich i szerokich porów, co umożliwia znaczny udział w procesie katalitycznym wewnętrznej powierzchni porów nośnika oraz ogranicza przeszkody dyfuzyjne w polimeryzacji. Polietylen otrzymywany wobec katalizatora osadzonego na otrzymanym przez nas nośniku charakteryzuje się dużym ciężarem cząsteczkowym (Mw >2 ź 10(6) ) w połączeniu ze stosunkowo wąskim (MWD <4) jego rozkładem. Polietylen ten ma korzystną dużą gęstość nasypową (tabela 2) i charakteryzuje się wąskim rozkładem granulometrycznym.

12

Enzyme electrodes constructed on basis of oxygen electrode with oxidases immobilised by sol-gel technique

Przybyt M., Białkowska B.

Materials Science

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2002

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Vol. 20, No. 2

63-79

EN

In this work, results of immobilisation of enzymes in silica gel on oxygen electrode are reported. As the model enzyme glucose oxidase was used. The influence of the composition of the casting solution (gel precursor, pH of the enzyme solution, sol-buffer ratio) on the electrode response was investigated. Also, the addition of ?-aminopropyltriethoxy silane to the casting solution was checked. The best electrode with stable signal was obtained, when the formed gel was not very rigid (buffer, pH 6 or 7 and high buffer-sol ratio). For the optimal composition of the casting solution, some properties of the glucose electrode were investigated (stability, pH profile and influence of temperature). The method of sol-gel entrappment was also used to obtain the electrodes sensitive for disaccharides by coimmobilisation of invertase, lactase and maltase with glucose oxidase. In addition, preliminary results for other oxidases immobilised by this method are presented.

13

Charakterystyka powłok TiC wytworzonych techniką zol-żel na ceramice narzędziowej.

Biedunkiewicz A.

Inżynieria Materiałowa

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2002

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R. XXIII, nr 5

364-367

PL

W artykule przedstawiono przegląd tytanoorganicznych kompleksów molekularnych stosowanych w charakterze prekursorów syntezy węglika tytanu. Metaloorganiczne kompleksy otwierają nowe drogi syntezy materiałów ceramicznych. Zaprezentowano opartą na metodzie zol-żel syntezę powłok Ti-C. Powłoki wytwarzano na płytkach wykonanych z węglików spiekanych i ceramiki tlenkowej. Próbki badano następującymi technikami analitycznymi: mikroskopia skaningowa, dyfrakcja rentgenowska i mikroanaliza rentgenowska.

EN

The review of titanoorganic molecular complexes used as precursor of TiC synthesis is presented. Metaloorganic complexes give new possibilities to ceramic materials' synthesis. The paper presents synthesis of Ti-C coatings on sintered Al2O3 and carbides (cutting tools) by sol-gel method. Samples were examined using the following analytical techniques: SEM, XRD, EDS, WDS.