A-Si/SiO nanolaminates for tuning the complex refractive index and band gap in optical interference coatings.

A- / nanolaminates are deposited by magnetron sputtering and show a decreasing absorption when the a-Si single-layer thickness is reduced from 2.4 to 0.7 .

Sample preparation for analytical scanning electron microscopy using initial notch sectioning.

A novel method for broad ion beam based sample sectioning using the concept of initial notches is presented. An adapted sample geometry is utilized in order to create terraces with a well-define d step in erosion depth from the surface. The method consists of milling a notch into the surface, followed by glancing-angle ion beam erosion, which leads to preferential erosion at the notch due to increased local surface elevation.

Optical bandgap control in AlO/TiO heterostructures by plasma enhanced atomic layer deposition: Toward quantizing structures and tailored binary oxides.

Atomically thin heterostructures and superlattices are promising candidates for various optoelectronic and photonic applications. Different combinations of AlO/TiO composites are obtained by plasma enhanced atomic layer deposition (PEALD). Their growth, composition, dispersion relation, and optical bandgap are systematically studied by means of UV/VIS spectrophotometry, spectroscopic ellipsometry (SE), x-ray reflectometry (XRR), scanning transmission electron microscopy(STEM) and x-ray photoelectron spectroscopy (XPS).

Nucleation efficacy and flexural strength of novel leucite glass-ceramics.

Objectives: To optimize the nucleation mechanism in leucite glass-ceramics to allow more efficacious glass-ceramic manufacture and improvements in microstructure and mechanical reliability.

Materials And Methods: An alumino-silicate glass was designed and synthesized using melt quench methods. The glass was crushed and milled using various milling times (48-93h) and spray drying.

Enhanced Magnetoelectric Coupling in BaTiO-BiFeO Multilayers-An Interface Effect.

Combining various (multi-)ferroic materials into heterostructures is a promising route to enhance their inherent properties, such as the magnetoelectric coupling in BiFeO3 thin films. We have previously reported on the up-to-tenfold increase of the magnetoelectric voltage coefficient α ME in BaTiO3-BiFeO3 multilayers relative to BiFeO3 single layers. Unraveling the origin and mechanism of this enhanced effect is a prerequisite to designing new materials for the application of magnetoelectric devices.

Sr[LiAlON]:Eu-A high performance red phosphor to brighten the future.

Innovative materials for phosphor converted white light-emitting diodes are in high demand owing to the huge potential of the light-emitting diode technology to reduce energy consumption worldwide. As the primary blue diode is already highly optimized, the conversion phosphors are of crucial importance for any further improvements. We report on the discovery of the high performance red phosphor Sr[LiAlON]:Eu meeting all requirements for a phosphor's optical properties.

Impact of magnetization and hyperfine field distribution on high magnetoelectric coupling strength in BaTiO-BiFeO multilayers.

Correlations were established between the hyperfine field distribution around the Fe atoms, the multiferroic properties, and the high magnetoelectric coefficient in BaTiO-BiFeO multilayer stacks with variable BiFeO single layer thickness, down to 5 nm. Of key importance in this study was the deposition of Fe - enriched BiFeO, which enhances the sensitivity of conversion electron Mössbauer spectroscopy by orders of magnitude. The magnetoelectric coefficient α reaches a maximum of 60.

The effect of TiO on nucleation and crystallization of a LiO-AlO-SiO glass investigated by XANES and STEM.

Glass ceramics based on LiO/AlO/SiO are of high economic importance, as they often show very low coefficients of thermal expansion. This enables a number of challenging applications, such as cooktop panels, furnace windows or telescope mirror blanks. Usually, the crystallization of the desired LAS crystal phases within the glasses must be tailored by a careful choice of crystallization schedule and type of nucleation agents to be used.

Redox effects and formation of gold nanoparticles for the nucleation of low thermal expansion phases from BaO/SrO/ZnO/SiO glasses.

Glasses in the system BaO/SrO/ZnO/SiO containing 0.01 and 0.1 mol% gold were used to study the formation of gold nanoparticles with the aim to use them as nucleation agents.

The formation of nanocrystalline ZrO nuclei in a Li2O-AlO-SiO glass - a combined XANES and TEM study.

The high economic importance of glass ceramics based on LiO/AlO/SiO (LAS) is mainly due to their low coefficients of thermal expansion (CTE), which make these materials suitable candidates for a number of applications. The exact mechanism of the crystallization processes in LAS glasses is still not fully understood. The present work focuses on the formation and development of nanocrystalline ZrO within an LAS base composition which contains only ZrO as nucleating agent.

Correlation of Interface Impurities and Chemical Gradients with High Magnetoelectric Coupling Strength in Multiferroic BiFeO-BaTiO Superlattices.

The detailed understanding of magnetoelectric (ME) coupling in multiferroic oxide heterostructures is still a challenge. In particular, very little is known to date concerning the impact of the chemical interface structure and unwanted impurities that may be buried within short-period multiferroic BiFeO-BaTiO superlattices during growth. Here, we demonstrate how trace impurities and elemental concentration gradients contribute to high ME voltage coefficients in thin-film superlattices, which are built from 15 double layers of BiFeO-BaTiO.

Surface Crystallization of a MgO/YO/SiO/AlO/ZrO Glass: Growth of an Oriented β-YSiO Layer and Epitaxial ZrO.

The crystallization behavior of a glass with the composition 54.7 SiO·10.9 AlO·15.

Mechanical, structural, and optical properties of PEALD metallic oxides for optical applications.

Structural, optical, and mechanical properties of AlO, SiO, and HfO materials prepared by plasma-enhanced atomic layer deposition (PEALD) were investigated. Residual stress poses significant challenges for optical coatings since it may lead to mechanical failure, but in-depth understanding of these properties is still missing for PEALD coatings. The tensile stress of PEALD alumina films decreases with increasing deposition temperature and is approximately 100 MPa lower than the stress in thermally grown films.

Characterizing the residual glass in a MgO/AlO/SiO/ZrO/YO glass-ceramic.

The non-isochemical crystallization of glasses leads to glass-ceramics in which the chemical composition of the amorphous matrix differs from that of the parent glass. It is challenging to solely analyse the properties of these residual glassy phases because they frequently contain finely dispersed crystals. In this study, the composition of the residual glass matrix after the crystallization of a glass with the mol% composition 50.

Bulk Crystallization in a SiO2/Al2O3/Y2O3/AlF3/B2O3/Na2O Glass: Fivefold Pseudo Symmetry due to Monoclinic Growth in a Glassy Matrix Containing Growth Barriers.

A glass with the mol% composition 17 Y2O3·33 Al2O3·40 SiO2·2 AlF3·3 Na2O·2 CeF3·3 B2O3 is heat treated at 1000 °C for 6-24 h. This results in the surface nucleation and growth of YAG. Nucleation and growth of star-shaped alumina and later of monoclinic β-Y2Si2O7 and orthorhombic δ-Y2Si2O7 are additionally observed in the bulk.

Coupling of metals and biominerals: characterizing the interface between ferromagnetic shape-memory alloys and hydroxyapatite.

Durable, mechanically robust osseointegration of metal implants poses one of the largest challenges in contemporary orthopedics. The application of biomimetic hydroxyapatite (HAp) coatings as mediators for enhanced mechanical coupling to natural bone constitutes a promising approach. Motivated by recent advances in the field of smart metals that might open the venue for alternate therapeutic concepts, we explore their mechanical coupling to sputter-deposited HAp layers in a combined experimental-theoretical study.

Variation of Zr-L2,3 XANES in tetravalent zirconium oxides.

Zr-L2,3 XANESs of tetravalent zirconium oxides with different coordination numbers and local symmetries are systematically investigated by ab initio multiplet calculations using fully relativistic molecular spinors for model clusters. Experimental Zr-L2,3 XANESs are obtained for SrZrO3, m-ZrO2 (monoclinic) and t-ZrO2 (tetragonal). The theoretical spectra are in good agreement with the experimental data.

Silicon nanocolumns on nanosphere lithography templated substrates: effects of sphere size and substrate temperature.

Glancing angle ion beam sputter deposition was used to grow regular arrays of Si nanocolumns with a nominal height of 650 nm at room temperature on polystyrene nanospheres with sphere diameters between 260 nm and 3550 nm, and at elevated temperatures on SiO2 nanospheres with a sphere diameter of 360 nm. Top view and cross sectional scanning electron microscopy reveals that the Si nanocolumns resemble cylinder-like structures, terminated by a hemispherical cap. Diameter, height and inter-column-spacing are found to depend linearly on the nanosphere diameter, thus giving the possibility to grow arrays of vertical Si columns with distinct porosities.

Effect of the LT-alpha (+250 G/A) polymorphism on markers of inflammation and clinical outcome in critically ill patients.

Background: Tumor necrosis factor alpha as a central mediator of the inflammation cascade is correlated to sepsis outcome. Tumor necrosis factor beta (LT-alpha) binds the same cell receptor and polymorphisms in both genes have been described. To evaluate the importance of the LT-alpha (+250 G/A) polymorphism for the clinical outcome of patients developing postsurgical sepsis, 85 patients were consecutively included into this study.