Characterization and synthesis of silver nanostructures in rare earth activated GeO2-PbO glass matrix using matrix adjustment thermal reduction method

This paper reports matrix adjustment thermal reduction method to synthesize silver nanostructures in Er3+/Yb3+ activated GeO2-PbO glass matrix. The GeO2-PbO glass, the medium of nanoparticle formation, doped with Er2O3, Yb2O3 and AgNO3 was prepared by a melt quenching method. Annealing of the glass for different times was utilized, not only due to thermally reduce Ag+ ions to Ag nanostructures, but also to influence the glassy network. This is because, the glass structural transformation temperature is near to 435 °C and heating at more than this temperature can cause some structural changes in the glass matrix. According to TEM images, samples that tolerate 450 °C annealing temperature for one hour show the formation of basil-like silver nanostructures with a mean length of 54 nm and mean diameter of 13 nm embedded in the glass matrix, whereas with annealing at 450 °C for 5 to 20 h, silver nanoparticles of about 3–4 nm mean diameter size are formed. Annealing for 30 h causes silver nanoparticles to aggregate to form larger particles due to an Oswald ripening process. Observation of the characteristic Ag-NP SPR band at 400–500 nm in the UV-visible absorption spectra confirms the existence of silver nanoparticles. The SPR band widens to longer wavelengths in one hour annealed samples, which relates to the existence of nanostructures with different size or fractal shapes. In addition, an increment in the peak of the SPR band by increasing the duration of annealing indicates the formation of more nanoparticles. Furthermore, the existence of a peak at 470 cm–1 in the FTIR spectra of annealed samples and its absence in the samples not exposed to an annealing process suggests that the glass matrix is polymerized by Pb-O chains during the 450 °C annealing process. This is the main source of different nanostructures because of the dissimilar stabilizing media. The tighter media cap the particles to form small and dense nanoparticles but a loose environment leads to the creation of basil-like particles in the glass matrix

The Thirteenth Annual Conference YUCOMAT 2011: Programme and the Book of Abstracts

The First Conference on materials science and engineering, including physics, physical chemistry, condensed matter chemistry, and technology in general, was held in September 1995, in Herceg Novi. An initiative to establish Yugoslav Materials Research Society was born at the conference and, similar to other MR societies in the world, the programme was made and objectives determined. The Yugoslav Materials Research Society (Yu-MRS), a nongovernment and non-profit scientific association, was founded in 1997 to promote multidisciplinary goal-oriented research in materials science and engineering. The main task and objective of the Society has been to encourage creativity in materials research and engineering to reach a harmonic coordination between achievements in this field in our country and analogous activities in the world with an aim to include our country into global international projects. Until 2003, Conferences were held every second year and then they grew into Annual Conferences that were traditionally held in Herceg Novi in September of every year. In 2007 Yu-MRS formed two new MRS: MRS-Serbia (official successor of Yu-MRS) and MRS-Montenegro (in founding). In 2008, MRS – Serbia became a member of FEMS (Federation of European Materials Societies)

The Thirteenth Annual Conference YUCOMAT 2011: Programme and the Book of Abstracts

The First Conference on materials science and engineering, including physics, physical chemistry, condensed matter chemistry, and technology in general, was held in September 1995, in Herceg Novi. An initiative to establish Yugoslav Materials Research Society was born at the conference and, similar to other MR societies in the world, the programme was made and objectives determined. The Yugoslav Materials Research Society (Yu-MRS), a nongovernment and non-profit scientific association, was founded in 1997 to promote multidisciplinary goal-oriented research in materials science and engineering. The main task and objective of the Society has been to encourage creativity in materials research and engineering to reach a harmonic coordination between achievements in this field in our country and analogous activities in the world with an aim to include our country into global international projects.\ud Until 2003, Conferences were held every second year and then they grew into Annual Conferences that were traditionally held in Herceg Novi in September of every year. In 2007 Yu-MRS formed two new MRS: MRS-Serbia (official successor of Yu-MRS) and MRS-Montenegro (in founding). In 2008, MRS – Serbia became a member of FEMS (Federation of European Materials Societies)

Planar waveguides obtained on commercial glass substrates by sol-gel and laser irradiation methods

The aim of the thesis is the fundamental study, design, fabrication and characterisation of photonic structures for spatial optic and, particulary, the interconnexion of optical devices. The research explored technologies and substrates for the fabrication of photonic structures based on the guided propogation of light and its application to research and development of integrated optical devices and improving the functionality of communication systems, which realises intelligent optical operations based on Fourier spatial transformed and image formation properties.At the same time, aims to explore new technologies for fabrication ofphotonic structures; which are repeatibility and not contaminants; and the product of well-defined charactericstics and low price

Advanced Photonic Sciences

The new emerging field of photonics has significantly attracted the interest of many societies, professionals and researchers around the world. The great importance of this field is due to its applicability and possible utilization in almost all scientific and industrial areas. This book presents some advanced research topics in photonics. It consists of 16 chapters organized into three sections: Integrated Photonics, Photonic Materials and Photonic Applications. It can be said that this book is a good contribution for paving the way for further innovations in photonic technology. The chapters have been written and reviewed by well-experienced researchers in their fields. In their contributions they demonstrated the most profound knowledge and expertise for interested individuals in this expanding field. The book will be a good reference for experienced professionals, academics and researchers as well as young researchers only starting their carrier in this field

Development of visible-to-ultraviolet upconversion phosphors for light-activated antimicrobial surfaces

A new form of antimicrobial surface was developed, which relies on an optical mechanism rather than chemical inactivation of microorganisms. Through the photoluminescence process of upconversion, low energy photons can be amplified into higher energy photons, and in this case, phosphors capable of converting visible light into germicidal UVC radiation were synthesized. Host crystals were doped with a praseodymium activator ion and shown to emit UVC photons upon excitation by blue or violet light. Surface coatings were prepared and proof-of-concept experiments demonstrated that, under exposure to a household fluorescent lamp, sufficient UVC radiation was emitted from the surfaces to achieve observable inactivation of surface bacterial spores and inhibition of biofilm growth. Material engineering was conducted to achieve higher optical conversion efficiency, wherein lithium codoping and development of alternative oxyfluoride host crystals were found to significantly improve upconversion emission. Implications of polychromatic excitation were investigated by conducting photoluminescence spectroscopy under combined laser beam excitation, while the effects of other application parameters are also discussed. These findings show that upconversion-based antimicrobial materials have strong potential for offering sustainable and effective technology for the prevention of diseases.PhDCommittee Chair: Jaehong Kim; Committee Member: Angus Wilkinson; Committee Member: Ching-hua Huang; Committee Member: John Crittenden; Committee Member: Seung Soon Jan

Glassy Materials Based Microdevices

Microtechnology has changed our world since the last century, when silicon microelectronics revolutionized sensor, control and communication areas, with applications extending from domotics to automotive, and from security to biomedicine. The present century, however, is also seeing an accelerating pace of innovation in glassy materials; as an example, glass-ceramics, which successfully combine the properties of an amorphous matrix with those of micro- or nano-crystals, offer a very high flexibility of design to chemists, physicists and engineers, who can conceive and implement advanced microdevices. In a very similar way, the synthesis of glassy polymers in a very wide range of chemical structures offers unprecedented potential of applications. The contemporary availability of microfabrication technologies, such as direct laser writing or 3D printing, which add to the most common processes (deposition, lithography and etching), facilitates the development of novel or advanced microdevices based on glassy materials. Biochemical and biomedical sensors, especially with the lab-on-a-chip target, are one of the most evident proofs of the success of this material platform. Other applications have also emerged in environment, food, and chemical industries. The present Special Issue of Micromachines aims at reviewing the current state-of-the-art and presenting perspectives of further development. Contributions related to the technologies, glassy materials, design and fabrication processes, characterization, and, eventually, applications are welcome

Ceramic Materials

This is the first book of a series of forthcoming publications on this field by this publisher. The reader can enjoy both a classical printed version on demand for a small charge, as well as the online version free for download. Your citation decides about the acceptance, distribution, and impact of this piece of knowledge. Please enjoy reading and may this book help promote the progress in ceramic development for better life on earth

Characterisation of Photo-Physical Properties of Upconversion Nanocrystals at Ensemble and Single Particle Level

Aufkonvertierungs-Nanokristalle (UCNPs), wie NaYF4 Kristalle, welche mit Yb3+ and Er3+ Ionen dotiert sind, emittieren höher energetisches Licht im ultravioletten/sichtbaren und nahinfraroten Bereich, nachdem sie mit weniger energiereichem nahinfraroten Licht angeregt wurden. Damit besitzen sie einzigartige optische Eigenschaften, wie verschiedenfarbige Emissionsbanden, verringerte Hintergrundfluoreszenz, größere Eindringtiefen in organisches Probenmaterial und eine hohe Lichtstabilität. Diese Eigenschaften sind besonders in der optischen Bioanalyse, in medizinischen und technischen Anwendungen von Vorteil. In dieser Arbeit werden die photophysikalischen und spektralen Eigenschaften von UCNPs im Ensemble und an Einzelpartikeln untersucht. Ein dafür entwickeltes konfokales Mikroskop ermöglicht Einzelpartikelmessungen bis in den Sättigungsbereich der UCNPs bei hohen Laser Anregungsleistungsdichten (P). Die erste Studie dieser Arbeit umfasst Ensemble- und Einzelpartikelmessungen an Kern und Kern-Schale -NaYF4 Kristallen, welche mit 20% Yb3+ und 1% bis 3% Er3+ Ionen dotiert sind, wobei die optischen Eigenschaften P-abhängig über sechs Größenordnungen untersucht wurden. Die zweite Studie diskutiert die Einflüsse bei starker Änderung der Yb3+/Er3+ Ionen Dotierung anhand von drei verschiedenen Probensystemen. Diese unterscheiden sich sowohl in der Partikelgröße als auch in der Synthesevorschrift. Bei der dritten Studie wurde die direkte Anregung von Yb3+ mit der von Nd3+ Ionen an Nd/Yb/Er dotierten NaYF4 Partikeln bezüglich des aufkonvertierten Lumineszenz Verhaltens in Wasser verglichen. In weiteren Messungen wurde sowohl der Lumineszenz Resonanz Energie Transfer (LRET) ausgehend von einem UCNP zu dem Farbstoff Sulforhodamine B, als auch plasmonische Wechselwirkungen von Au-Schale UCNPs bei Einzelpartikelmessungen untersucht.Upconversion nanoparticles (UCNPs), such as, NaYF4 crystals co-doped with Yb3+ and Er3+ ions, emit higher energetic light in the UV/vis and NIR range under lower energetic NIR excitation. This generates unique optical properties, for example, multi-colour band emissions, reduced background fluorescence, deeper tissue penetration depths and high photostability rendering UCNPs attractive options for bioimaging, medicinal and engineering applications. In this thesis the influence of multi-factor parameters on the photo-physical and spectroscopic properties of UCNPs are investigated under ensemble and single particle (SP) condition. For this purpose, a confocal laser scanning microscope was constructed to enable the characterisation of individual UCNPs up to their saturation conditions at high laser power densities (P). At first, ensemble and SP studies of core- and core-shell -NaYF4 crystals co-doped with 20% Yb3+ and 1% to 3% Er3+ are performed over a P-range of six orders of magnitude. The second part of this thesis discusses influences in a wide variation in Yb3+/Er3+ ion doping concentration. Thereby, three different sample sets of varying size have been studied, using different synthesis approaches. A comparison of the Nd- and Yb-excitation of Nd/Yb/Er triple-doped NaYF4 UCNPs regarding their upconversion luminescence performance in water is provided in the third section of the thesis. In further studies, the process of luminescence resonance energy transfer (LRET) from an UCNP to the sulforhodamine B dye and the plasmonic interaction of an Au-shelled UCNP have been examined at the SP level