Hybrid Glasses Research Articles

Ultrafast dynamics of Auramine O in composite films

Ultrafast excited-state dynamics of Auramine O, a diphenylmethane dye, in polymethylmethacrylate (PMMA) and in hybrid organic/inorganic sol–gel based films have been studied by means of femtosecond fluorescence upconversion experiments. The fluorescence transients of the samples showed a fast decay (few picoseconds) and a long decay (hundreds of picoseconds) representing a rapid cooling of the excess excitation energy to the matrices and the excited-state lifetime of the dye molecules, respectively. Different dynamic Stokes shifts in PMMA and hybrid glasses have been observed, which is argued to be ascribed to the different couplings between the emissive and nonemissive excited states for the two types of matrices.

Spectroscopic and dielectric studies of meso-tetrakis(p-sulfonatophenyl) porphyrin doped hybrid borate glasses

Hybrid borate glasses containing different concentrations of meso-tetrakis(p-sulfonatophenyl) porphyrin sodium salt (TPPS 4) were prepared. The obtained glass samples were found to be transparent and homogeneous. Formation of TPPS 4-J-aggregates in borate glass was investigated by means of optical absorption, steady state and time resolved fluorescence spectroscopy. The hybrid glasses exhibit a strong S 2→S 0 emission at ∼473 nm and J-aggregates show emission at ∼733 nm. Time resolved fluorescence show two exponential decay with lifetime of τ 1 = 65 ± 10 ps (∼80%) and τ 2 = 3.87 ± 0.1 ns (∼20%) respectively. Dielectric properties such as dielectric constant ( ɛ′), dielectric loss (tan δ) and ac conductivity ( σ ac) over a range of frequency and temperature of these glasses were studied. The ac conductivity was found to be proportional to ω s (where s < 1). The observed change in dielectric parameters due to different concentrations of TPPS 4 has been analyzed in light of different polarization mechanisms.

Molecular Origins of the Mechanical Behavior of Hybrid Glasses

AbstractHybrid organic‐inorganic glasses exhibit unique electro‐optical properties along with excellent thermal stability. Their inherently mechanically fragile nature, however, which derives from the oxide component of the hybrid glass network together with the presence of terminal groups that reduce network connectivity, remains a fundamental challenge for their integration in nanoscience and energy technologies. We report on a combined synthesis and computational strategy to elucidate the effect of molecular structure on mechanical properties of hybrid glass films. We first demonstrate the importance of rigidity percolation to elastic behavior. Secondly, using a novel application of graph theory, we reveal the complex 3‐D fracture path at the molecular scale and show that fracture energy in brittle hybrid glasses is fundamentally governed by the bond percolation properties of the network. The computational tools and scaling laws presented provide a robust predictive capability for guiding precursor selection and molecular network design of advanced hybrid organic‐inorganic materials.

Structural and photophysical evaluation of Au-NPs/SiO 2-based inorganic–inorganic sonogel hybrid composites

SiO 2-based inorganic–inorganic hybrid sonogels were prepared with Au/SiO 2 supported nanoparticles (NPs). The well-established catalyst-free (CF) sonogel route was successfully implemented to produce these optically active nano-composites by doping the liquid sol-phase with Au/SiO 2-NPs synthesized according to the [Au(en) 2] 3+-cation-adsorption method. Prepared Au/SiO 2-NPs exhibited low 2D-HCP crystallinity with particle diameters below 10 nm and homogeneous size distribution. The easy Au/SiO 2-NPs loading within the mesoporous dielectric sonogel network evidenced the huge chemical affinity between the highly pure CF-sonogel host and the guest Au/SiO 2-NPs. This fact allowed us to fabricate rigid monoliths with controllable geometrical shapes suitable for optical characterizations. Indeed, the host system provided thermal and mechanical stability protecting the active metallic NPs from environment conditions and diminished their tendency to from aggregates, thus, preserving their pristine optical properties and producing sol–gel hybrid glasses appropriate for optical applications. Comprehensive morphological, structural, spectroscopic, photo-physical and nonlinear optical (NLO) characterizations were performed on the obtained hybrids. Results show that Au/SiO 2-NPs were homogeneously embedded within the highly pure SiO 2-sonogel network. The crystalline nature, random orientation and small sizes of the Au/SiO 2-NPs, together with the guest–host bulk interactions, allowed the observation of improved spectroscopic and quadratic NLO-properties for the developed amorphous-based hybrids.

Infrared Characterization of PMMA-SiO2 Hybrid Glasses Obtained by Sol-Gel Process

AbstractThis work is about the production of hybrid coatings of the system SiO2-PMMA (PMMA, polymethylmethacrylate). These materials have interesting mechanical and chemical properties useful for anticorrosive and wear resistance applications. SiO2-PMMA hybrids were obtained by the sol-gel traditional process, using tetraethylorthosilicate (TEOS) and methylmethacrylate (MMA) by Aldrich Co, as starting reagents. The SiO2:PMMA ratio was varied from 0:1 to about 1:1 at air atmosphere deposition. The coatings were obtained on acrylic sheets and silicon wafers. A diversity of coatings with chemical composition ranging from SiO2 and PMMA to obtain the SiO2-PMMA hybrids were obtained. Infrared (IR) and atomic force microscopy (AFM), were performed to determinate structural and morphological behavior.

Structure of hybrids based on TEOS-cyclic forms of siloxane system

Hybrid glasses based on tetraethoxysilane (TEOS) modified by addition of selected cyclosiloxanes have been prepared by sol–gel method. Octamethylcyclotetrasiloxane (D4) and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylsiloxane (VMC) have been chosen as an organic modifier of the silica matrix. Molar ratio of TEOS to cyclosiloxane varied from 1:0 to 1:0.5. Structure of prepared hybrids has been studied by infrared spectroscopy (FTIR), photoelectron spectroscopy (XPS) and nuclear magnetic resonance spectroscopy (NMR). Optical properties of bulk glasses in the visible range have also been reported.

Preparation and morphological and optical characterization of azo-polymer-basedSiO2 sonogel hybrid composites

The well-established catalyst-free sonogel route was successfully implementedto fabricate highly pure, optically active, solid state polymeric azo-dye/SiO2-based hybrid composites. Bulk samples exhibit controllable geometrical shapes andmonolithic structure with variable dopant concentrations. Since the implemented azo-dyechromophores exhibit a push–pull structure, hybrid film samples were spin-coated onITO-covered glass substrates; molecular alignment was then performed via electrical polingin order to explore the quadratic nonlinear optical performance of this kind of composite.Comprehensive morphological, spectroscopic and optical characterization of the sampleswere performed with several experimental techniques: atomic force microscopy,x-ray diffraction and infrared, Raman, photoluminescent and ultraviolet–visiblespectroscopies. The linear refractive indices of both bulk and thin film samples weremeasured according to the Brewster angle technique and a numerical analysis of thetransmission spectral data, respectively. Regardless of the low glass transitiontemperatures of the studied polymers, some hybrid film samples were able to displaystable nonlinear optical activity such as second harmonic generation. Resultsshow that the chromophores were satisfactorily embedded into the highly pureSiO2 sonogel network without significant guest–host molecular interactions, thus preserving theiroptical properties and producing sol–gel hybrid glasses suitable for optical applications.

International Seminar on Science and Technology of Glass Materials (ISSTGM-2009)

The progress of the human race is linked with the development of new materials and also the values they acquired in the course of time. Though the art of glass forming has been known from Egyptian civilization, the understanding and use of these glasses for technological applications only became possible once the structural aspects were revealed by the inspiring theories proposed by William H Zachariasen. Glass and glass ceramics have become the essential materials for modern technology. The applications of these materials are wide and cover areas such as optical communication, laser host, innovative architecture, bio-medical, automobile and space technology. As we master the technology, we must also learn to use it judiciously and for the overall development of all in this global village.The International Seminar on Science and Technology of Glass Materials (ISSTGM-2009) is organized to bring together scientists, academia and industry in order to discuss various aspects of the technology and to inspire young scholars to take up fruitful research. Various topics such as glass formation and glass-ceramics, glass structure, applications of glass and glass ceramics in nuclear waste management, radiation dosimetry, electronics and information technology, biotechnological applications, bulk metallic glasses, glasses containing nano-particles, hybrid glasses, novel glasses and applications in photonics, Non-linear optics and energy generation were discussed.In this volume, 59 research articles covering 18 invited talks, 10 oral presentations and 31 poster presentations are included. We hope these will serve as a valuable resource to all the scientists and scholars working with glass materials.Acharya Nagarjuna University, established in 1976, is named after the great Buddhist preceptor and philosopher, Acharya Nagarjuna, who founded a university on the banks of river Krishna some centuries ago. The University is situated between Vijayawada and Guntur, the famous commercial and academic centers of Andhra Pradesh, India. The Departments of Physics of Acharya Nagarjuna University and the Nuzvid Campus have existed since the inception of the University. For the past decade and a half, these Departments have been actively involved in research on glass materials. More than 200 research articles have been published by staff members of these departments exclusively on glass materials. A number of Major Research Projects are being carried out by the staff members of these Departments. The organizing committee is indebted to all the scientists and scholars for their active participation in the seminar and their contribution to this proceedings. The committee expresses its gratitude to the authorities of Acharya Nagarjuna University (The Vice-Chancellor, The Rector and The Registrar), Department of Atomic Energy, Board of Research in Nuclear Sciences, Department of Science and Technology, Council of Scientific and Industrial Research, Defence Research and Development Organization and AP State Council of Science and Technology for their financial support. The committee thanks the IOP: Conference Series publisher for publishing this proceedings which added value to the seminar. Professor N Veeraiah Convener and Editor-in-Chief Professor D Krishna Rao Co-Convener

Preparation and optical and electrical evaluation of bulk SiO 2 sonogel hybrid composites and vacuum thermal evaporated thin films prepared from molecular materials derived from (Fe, Co) metallic phthalocyanines and 1,8 dihydroxiantraquinone compounds

Semiconducting molecular material of PcFe(CN)L1 and PcCo(CN)L1 (L1 = 1,8 dihydroxianthraquinone), PcFe(CN)L2 and PcCo(CN)L2 (L2 = double potassium salt of 1,8 dihydroxianthraquinone) have been successfully used to prepare thin film and bulk sol–gel hybrid optical materials. These samples were developed according to the vacuum thermal evaporation technique and the catalyst-free sonogel route, respectively. Thin films samples were deposited on Corning glass substrates and crystalline silicon wafers and were characterized by infrared (FTIR), Raman and ultraviolet-visible (UV–vis) spectroscopies. IR-spectroscopy and Raman studies unambiguously confirmed that the molecular material thin films exhibit the same intra-molecular bonds, which suggests that the thermal evaporation process does not alter these bonds significantly. These results show that it is possible to deposit molecular materials of PcFe(CN)L2 and PcCo(CN)L2 on Corning glass substrates and silicon wafers. From the UV–vis studies the optical band gap ( E g) was evaluated. The effect of temperature on conductivity was also evaluated in these samples. Finally, the studied molecular systems dissolved at different concentrations in tetrahydrofuran (THF) were successfully embedded into a highly pure SiO 2 sonogel network generated via sonochemical reactions to form several solid state, optically active sol–gel hybrid glasses. By this method, homogeneous and stable hybrid monoliths suitable for optical characterization can be produced. The linear optical properties of these amorphous bulk structures were determined by the Brewster angle method and by absorption-, Raman- and photoluminescent (PL)-spectroscopies, respectively.

New Version of Laser Device Materials for Developing Diffraction Beam Modulators; Novel Nano -periodic Structures

AbstractCro/CrOx-doped hybrid glasses are designed to develop novel laser device materials by inserting alkylene spacers between inorganic oxides. In TEM images, morphology of the organically modified hybrid glasses reveals highly arranged nano-periodic patterns. The nano-patterns observed from the hybrid glass based on alkylene-bridged xerogel are sustained over substantial domains and appears to arise from modified glassy lattice fringes. In electron diffraction pattern, it also shows the circled diffraction patterns arise from Cro/CrOx. In laser experiments, the hybrid glass shows a new optical property, which generates a huge acoustic wave; the diffraction efficiency (45 %) of the modified glass is higher than that of methanol (25 %); it means that the compressibility of the solid type of glass is as effective as the liquid. The hybrid glass shows a new optical property that hitherto hasn’t been found and could be useful for developing diffraction beam modulators.

Optical Glass Effectively Generating a Large Acoustic Wave for Diffraction Beam Modulator Applications

A transparent organic/inorganic hybrid glass containing a composite of chromium/chromium oxides has been synthesized by sol−gel copolymerization. Nanocomposites often lose individual identities then create new properties. In this study, a set of new optical properties created from the organically modified silicate glasses was observed. In our laser experiments, the hybrid glass shows a new optical property, generation of a huge acoustic wave; the diffraction efficiency (45%) of the organically modified glass is higher than that of methanol (25%), which means the compressibility of the hybrid glass is as effective as the liquid. These organic/inorganic hybrid glasses have properties that may function as a new type of laser device materials with applications in, for example, diffraction beam modulators.

Acquisition of gated spectra from a supercontinuum using ultrafast optical Kerr gate of lead phthalocyanine-doped hybrid glasses

We demonstrated the selection of the chirped supercontinuum using an ultrafast optical Kerr gate (OKG) of lead phthalocyanine (PbPc)- doped hybrid glasses. Using the OKG, narrow bandwidth and symmetrical gated spectra were obtained continuously from the chirped supercontinuum generated in a sapphire plate with a femtosecond laser. Experimental results show that the obtained Kerr-gated spectra using the PbPc-glass have many advantages comparing with that using CS(2).

Reply to Comment on “Highly Fluorescent Rhodamine B Nanoparticles Entrapped in Hybrid Glasses”

Reply to Comment on “Highly Fluorescent Rhodamine B Nanoparticles Entrapped in Hybrid Glasses”

Possible Artifacts of Fluorescence of Dyes in Concentrated Materials: Comment on “Highly Fluorescent Rhodamine B Nanoparticles Entrapped in Hybrid Glasses”

Possible Artifacts of Fluorescence of Dyes in Concentrated Materials: Comment on “Highly Fluorescent Rhodamine B Nanoparticles Entrapped in Hybrid Glasses”

Characteristics of colored inorganic–organic hybrid materials

Inorganic–organic hybrid glasses are relatively new nanometric materials of Ormosil’s group (organic modified silicates). There co-existence, on a molecular scale, exists between inorganic structures in the form of silica-oxide network and organic structures based on carbon links. Properties of these materials are intermediate between those of inorganic glasses (hardness, chemical and thermal resistance) and organic polymers (low temperature of obtaining, elasticity of structure). The hybrid materials are compatible matrices for organic compounds such as organic dyes, laser dyes, photo-chromic compounds, etc. Inorganic–organic hybrid glasses are usually produced in the form of thin coatings on various bases using a low-temperature sol-gel process. These coatings, depending on the kind and amount of units, building their structure, show various properties: refractive index changing in a wide range, anti-static properties, anti-reflection, corrosion protection, intensive color, luminescence and others. That is why these materials found application as protective and colored covering of glass articles as well as in new technical areas. The aim of this paper is obtaining and characterizing colored inorganic–organic coatings on glass, considering both protective and colored properties. These materials have been produced from phenyltriethoxysilane (PhTES), 3-glycidoxypropyltrimethoxysilane (GPTMS), aluminium tri-sec-butylate (TBA); (PGT matrix). The structure of PGT matrix was determined using the FTIR, 29Si MAS NMR and 27Al MAS NMR examinations. It has been found that chemical bonds occur between structural units. The two groups of organic dyes were used for coloring the coatings. The first group consisted of ORASOL dyes, chiefly based on various metal complexes. These dyes have a wide range of commercial utilization. The second group included the organic, intensive dyes obtained in the laboratory and are inaccessible for sale. The coloring coatings were coated on flat glass using the dip-coating method. The samples were submitted for thermal treatment at temperatures of 100 and 200 °C. Investigation of chemical resistance (boiling in water for 1 h) was made for coated materials after thermal treatment at 100 °C. UV–VIS transmission of colored coatings was examined after each stage of thermal treatment and also after hydrolytic resistance examination. The quality of the coatings and their thickness were estimated by SEM observations. The obtained, inorganic–organic coatings were characterized by good chemical resistance and stability of color.

A chemical strategy to improve the fluorescence environments of erbium-ions doped into organically modified hybrid glasses for laser amplifier applications

Bridged polysilsesquioxanes, a class of hybrid organic/inorganic siloxanes, are employed to manipulate the fluorescence environments of rare-earth metal ions. The performance of silsequioxanes containing rare-earth ions in optical devices significantly relies on host materials’ properties. We have developed organically modified fluoroalkylene-bridged polysilsesquioxanes doped with Er 3+/CdSe nano-particles. Solid state silicon NMR analysis of undoped xerogels indicate an enhanced condensation in fluorinated xerogel compared to that of alkylene-bridged silsesquioxanes. Fluoroalkylene-bridged xerogel containing Er 3+-ions shows significantly reduced absorptions at the 1540 nm by reducing amounts of uncondensed hydroxyl groups. The presence of CdSe nano-particles influences the fluorescence environment of Er 3+-ions in different glassy hosts, resulting in the increased fluorescence intensity.

Organic/Inorganic Hybrid Glasses Doped with (Erbium-ions/CdSe) Nanoparticles for Laser Amplifications

AbstractHybrid organic/inorganic silicate materials are employed to incorporate rare-earth metal ions for laser amplification applications. Performance of laser amplifiers doped with rare-earth ions significantly relies on glassy hosts. We thus designed and synthesized highly fluorinated glassy hosts doped with biphase of Er3+/CdSe nano-particles. Fluoroalkylene-bridged xerogels containing Er3+-ions show low absorptions at the 1540 nm in this study. The presence of CdSe nano-particles also significantly influences the fluorescence environment of Er3+-ions in the fluorinated glassy matrices.

Highly Fluorescent Rhodamine B Nanoparticles Entrapped in Hybrid Glasses

Rhodamine B (RB) nanoparticles entrapped in hybrid glasses show enhanced fluorescent emission (approximately 220-fold larger than that of single RB molecules) thanks to the configuration control of the self-assembled aggregates that form the supramolecular architecture of the nanoparticles. The fluorescence performance reported in this work is around 1 order of magnitude larger than that recently reported for fluorescent Nile Red nanoparticles. The fluorescence enhancement results from the use of a highly efficient fluorescent dye such RB and the formation of larger nanoparticles. Note that the later implies the presence of a large number of emitting centers involved in the fluorescence emission.

Gel-melting method for preparation of organically modified siloxane low-melting glasses

Softening or melting behavior of the organically-modified siloxane hybrid gels and glasses in the system of RSiO3/2 and R2SiO2/2 (R: methyl and phenyl) has been investigated to obtain a new family of low-melting glasses. The RSiO3/2 and RSiO3/2–R2SiO2/2 gels showed softening temperatures around 50–100 °C. The softening temperature of RSiO3/2 single-component glasses, which were obtained by melting the corresponding gels at a temperature above the softening temperature, increased by heat-treatment at 200 °C, and finally showed no softening behavior. On the other hand, in the PhSiO3/2–Ph2SiO2/2 binary glasses, the softening temperatures showed a tendency to saturate after longer heat treatment over 200 h. These facts indicate that the present organically modified siloxane system will be a potential candidate for the low-melting glass.

Structural studies of TEOS-tetraethoxytitanate based hybrids

Hybrid glasses prepared by sol–gel method are considered as promising candidates for corrosion protection coatings. Hybrids based on TEOS (tetraethylorthosilicate)–TEOT (tetraethylorthotitanate)–GLYMO (3-glicydoxypropyltrimethoxysilane) and TEOS–TEOT–MTMS (methyltrimethoxysilane) systems were synthesized by sol–gel method. Structure of the glasses was studied by FTIR, XPS and optical spectroscopy. It was revealed that the titanium is present in tetrahedral and octahedral coordination. High resolution SIMS technique was used to verify homogeneity of the layers.