In this work high quality ferroelectric PZT films have been prepared in-situ by hot RF magnetron sputtering. 200 mm wafer were coated with PZT films of 1 μm and 2 μm thickness at sputter rates of 45 nm/min in a high volume production sputtering tool. The films were grown on oxidized Si substrates prepared either with sputtered Ti/TiO2/Pt, sputtered Ti/TiO2/Pt/TiO2 or evaporated Ti/Pt bottom electrodes at substrate holder temperatures in the range from 550 °C to 700 °C. At these temperatures, the material nucleates in the requisite piezoelectric perovskite phase without need of an additional post annealing treatment.

The films were investigated with respect to their chemical composition and their crystallographic, piezoelectric and dielectric properties. At an intermediate chuck temperature of 600 °C the PZT thin films were characterized by a minimum volume fraction of secondary nonpiezoelectric phases. A Zr/(Zr+Ti) ratio of 0.53 has been achieved matching the morphotropic phase boundary. By improving the deposition process and poling procedure, a notable high e31,f coefficient of -17.3 C/m2 has been obtained. The corresponding longitudinal piezoelectric constant was determined to have an effective longitudinal piezoelectric coefficient d33,f of 160 pm/V.

Initial tests are performed regarding the degradation of lattice-mismatched GaInAs solar cells. 1eV metamorphic GaInAs solar cells with 1-2×106 cm-2 threading dislocation density in the active region are irradiated with an 808 nm laser for 2 weeks time under a variety of temperature and illumination conditions. All devices show a small degradation in Voc that is logarithmic with time. The absolute loss in performance after 2 weeks illuminated at 1300 suns equivalent and 125°C is 7 mV Voc and 0.2% efficiency, showing these devices to be relatively stable. The dark current increases with time and is analyzed with a two-diode model. A GaAs control cell degrades at the same rate, suggesting that the observed degradation mechanism is not related to the additional dislocations in the GaInAs devices.

In this work slow strain rate tests (SSRT) were used for the evaluation of API 5L X60 in contact with a simulated soil solution called NS4 in order to evaluate stress corrosion cracking (SCC) susceptibility. SSRT were carried out in NS4 solution at room temperature to simulate dilute ground water that has been found to be associated with SCC of low carbon steel pipelines. A strain rate of 1x10-6 sec-1 was used. According to the analysis of SSRT results, the X60 pipeline steel is highly resistant to SCC at the conditions studied. A combine fracture type it was observed: ductile and brittle with a transgranular appearance. Some pits close to the fracture zone were observed. The failure process and mechanism of X60 steel in NS4 solution are controlled by anodic dissolution and hydrogen embrittlement which was revealed with the internal cracks observed in the surface fracture. There is a relation between the strength of the steel and the SCC susceptibility, thus, increasing strength in the steel, the SCC susceptibility increases as a function of the pH solution used.

Silver triangular nanoprisms (TNP’s) were transformed into silver nanodisks (NDK’s) by addition of halide ion solution (chloride, bromide and iodide). The shape transformation of the TNP’s is due to the selective etching effect of halide ions at their vertices. TNP’s were synthesized via a photoinduced growth process, and then different concentrations of potassium halide solutions were added into the TNP’s colloids under vigorous stirring. Images of the obtained nanoparticles were recorded by scanning electron microscopy (SEM). The shifts of the in-plane dipole plasmon resonance band allow us to identify the differences among the three halides. These differences might be due to the distinct sizes of halides, and the solubility product constant values of each silver halide. We found that the etching ability of the halides, at a concentration of 1.0 mM, to truncate the vertices of TNP’s is in the order of Br- > Cl- > I-. In contrast, at a concentration of 0.01 mM, the order of the etching ability is Br- > I- > Cl-.

Gold nanorods (NRs) were fixed on an ITO plate and used for theSurface-Assisted Laser Desorption/Ionization Time-of-Flight MassSpectrometry (SALDI-MS) of oligopeptides (angiotensin I). The SALDI-MSmeasurements had a high sensitivity to the angiotensin on the ITO plate onwhich isolated NRs were deposited. Angiotensin molecules in a very dilutedsolution (1 × 10-11 M) could be detected at m/z = 1297 with agood signal/noise ratio (S/N = 18). In contrast, alternatively deposited NRan ITO plate, which present broad surface plasmon bands, was found to beinactive for SALDI measurements.

In this study different powder metallurgical processing routes, commonly used for refractory metal based materials, were evaluated on their impact on mechanical properties of a multi-component Nb-20Si-23Ti-6Al-3Cr-4Hf (at.%) alloy. Powder was produced by gas-atomization or high energy mechanical alloying of elemental powders and then consolidated either by HIPing or powder injection molding (PIM). The PIM process requires fine particles. In this investigation powder batches of gas-atomized powder (< 25 μm) and mechanically alloyed powder (< 25 μm) were compacted via PIM. Fine (< 25 μm) and coarser (106-225 μm) particle fractions of gas-atomized powder were compacted via HIPing for comparison. Quantitative analysis of the resulting microstructures regarding porosity, phase formation, phase distribution, and grain size was carried out in order to correlate them with the ensuing mechanical properties such as compressive strength at various temperatures.

It was found for the first time that the control of the size of pore sealant is important to prevent diffusions of pore sealant into pores of porous low-k films and to achieve a good toluene seal property. Two pore sealants (PS-A, B) were prepared and the seal property and porous structure were studied using toluene based ellipsometric porosimetry (EP) measurements. It was revealed that small pore sealant (PS-B) diffuses into pores of porous low-k (PLK) films and did not show any seal property, while large pore sealant (PS-A) does not diffuse into pores of porous low-k films and shows a good toluene seal property. Ellipsometry shows that PS-A forms conformal layer only on the vicinity of surface of porous low-k films, but porous structure of porous low-k films at the bottom part is kept, according the fact that the refractive index did not increase.

Furthermore, we developed a new pore seal material (PS-C) to form ultra-thin conformal layer by a single pass, which shows a good toluene seal property. The dielectric constant increased from 2.10 to 2.25 by covering with PS-C. The obtained layer also shows the effect as the protect layer of porous low-k films from plasma damages.

A comparative study of two blue pigment found in separate megalithic structures in Yucatán México is presented. The first sample (M1) is a piece of turquoise stucco discovered at the top of a building known as Structure-2 in the town of Dzilam González. The second sample (M2) is a residual blue powder that was contained in a Oxcum Café type ceramic vessel recovered in the rubble of the Kabul building in Izamal city. The interest in characterizing these samples increases with the possibility of finding in them evidence of Maya Blue, a dye created in the eighth century by the Maya people, whose extraordinary physical and chemical properties have been studied in laboratories around the world. Maya Blue was a tailored technology used for several centuries, even during the Spanish occupation, throughout Mesoamerica. Despite 80 years of study, the mysteries of its composition, traditional preparation and obsolescence have not yet been fully resolved. Using different spectroscopic techniques (SEM, EDX, XRD, FTIR, UV-Vis DR) we have studied and compared the blue colorants in M1 and M2. Results indicate that M1 is Maya Blue. Despite some similarities in the infrarred vibrational spectra of the two samples, we have determinated that M2 is not Maya Blue but a non-Mesoamerican mineral pigment known as Ultramarine which was probably introduced to America by Europeans.

Multi-frequency atomic force microscopy (AFM) offers additional response signals in comparison to traditional dynamic AFM. Furthermore, depending on the mode of operation used, the higher eigenmode responses are generally not directly influenced by the topographical acquisition control loops, such that they can explore a fuller range of tip-sample interactions. In this work we describe the implementation of multi-frequency imaging schemes that enable the acquisition of topographical, phase and frequency shift contrast in tapping-mode operation. This type of characterization can be especially useful for soft, highly dissipative samples, such as polymers, for which the various response channels can exhibit significantly different response, thus providing complementary information. We discuss typical results obtained as well as important challenges that need to be addressed in order to develop a fully quantitative technique.

Dendrons with dodecyl ended groups joined benzyloxy moieties were attached to a cyclotriveratrylene core. The dendrimers were used in Diederich cyclopropanation reaction with the fullerene C60. The structure of the synthesized dendrimers was confirmed by 1H- and 13C-NMR, MALDI-TOF mass spectrometry and elemental analysis.

Recent trends in composite research include the development of structural materials with multiple functionalities. In new studies, novel materials are being designed, developed, modified, and implemented into composite designs. Typically, an increase in functionality requires additional material phases within one system. The presence of excessive phases can result in deterioration of individual or overall properties. True multi-functional materials must maintain all properties at or above the minimum operating limit. In this project, samples of Sb-doped SnO2(ATO) sol-gel solutions are used to coat carbon fibers and are heat treated at a temperature range of 200 – 500 °C. Results from this research are used to model the implementation of sol-gel coatings into carbon fiber reinforced multifunctional composite systems. This research presents a novel thermo-responsive sol-gel/ (dopant) combination and evaluation of the actuating responses due to various heat treatment temperatures. While ATO is a well-known transparent conductive material, the implementation of ATO on carbon fibers for infrared thermal reflectivity has not been examined. These coatings serve as actuators capable of reflecting thermal infrared radiation in mid-range and near-range wavelengths (λ). By altering the ATO sol gel thickness and heat treatment temperatures, optimal optical properties are obtained. While scanning electron microscopy (SEM) is used for imaging, electron diffraction spectroscopy (EDS) is used to verify the compounds present in the coatings. Fourier transform infrared (FT-IR) spectroscopy was performed to analyze the reflectivity in the infrared spectra and analyze the crystal structures after heat treatments.

A genetically modified M13 bacteriophage template was used to biomineralize ZnO. A peptide, EAHVMHKVAPRP [1], with a known affinity for ZnO was genetically displayed on each of five copies of the pIII protein located at one tip of the M13 virus. Site-directed assembly using this pIII peptide fusion was studied using a variety of precursor concentrations, incubation times, and phage concentrations. For comparision, free ZnO-binding peptides were also used to biomineralize ZnO. Isolated, polydisperse, spherical ZnO nanoparticles were formed at all mineralization conditions containing the ZnO-binding M13 bacteriophage, whereas free peptide mineralization resulted in smaller, more irregularly shaped particles which agglomerated at longer incubation times. These studies are preliminary experiments in the investigation of ZnO biomineralization on the various structural proteins of the M13 bacteriophage and cooperative effects which occur between neighboring peptides.

3D x-ray diffraction contrast tomography (DCT) is a non-destructive technique for the determination of grain shape and crystallography in polycrystalline bulk materials. Using this technique, a strontium titanate specimen was repeatedly measured between annealing steps.. A systematic analysis of the growth history of selected grains before and after the ex-situ annealing step allows to extract the topological and morphological changes during grain growth. Furthermore, misorientation as well as interface orientation information of the microstructure reconstructions have been determined. The interface normal distribution clearly shows a preference for (100) oriented interfaces in the selected grains when annealed at 1600°C. This observation can be connected to existent interfacial energy estimations resulting from capillarity vector reconstructions.

For inorganic semiconductor solar cells, controlled doping is important because it can cause Fermi level shift of the inorganic semiconductor and achieve ohmic contact at the metal-semiconductor interface. In this paper we show that doping can also be used to shift Fermi level in organic semiconductors and cause changes in solar cell performance. We have made chloroindium phthalocyanine (ClInPc)/C60 heterojunction solar cells, where tetrafluoro-teracyano-quinodimethane (F4-TCNQ) is used to dope ClInPc layer. Ultraviolet photoemission spectroscopy (UPS) is used to investigate the ITO/ClInPc interfaces. The result shows that doping causes a Fermi level shift at the ITO/ClInPc interface as it does for inorganic semiconductors. As the doping increases, dark saturation current J0 of the solar cell increases, while open-circuit voltage Voc, short-circuit current Jsc and fill factor decreases. As a result, the efficiency of the solar cell decreases as doping increases. More UPS studies on ClInPc (doped with F4TCNQ)/C60 junction are needed to correlate the energy band diagram of the whole solar cell structure with the J-V characteristics.

The art and science of using biological tissue grafts from animal and humansources for various ailments is nascent. Various research groups around theworld are actively investigating the potential prostheses of biologicalorigin. Biological tissue grafts are rendered acellular through variousmethods of processing and fabrication before they are used for the specificpurpose. The remainder is a scaffold that offers framework for host cellularrepopulation and revascularization. Different methods of fixation have beenexplored over several decades to render the biological grafts suitable foruse with or without extraction of cells. Therefore, methods such asglutaraldehyde and polyepoxide crosslinking treatments and dye-mediatedphotooxidation have been developed to stabilize and deantigenize the tissuewhile attempting to maintain its natural mechanical properties. Also,residual cellular components in a bioprosthetic material have beenassociated with undesired effects, such as calcification and immunologicalrecognition, and thus have been the motivation for various decellularizationprocesses. The effects of these stabilization and decellularizationtreatments on mechanical, biological and chemical properties of treatedtissues have been investigated, specifically with regard to calcification,immunogenicity, and cytotoxicity concerns. Naturally derived biologicalscaffolds offer many mechanical, chemical and biological advantages oversynthetic materials, and thus hold tremendous potential for use in tissueengineering therapies. Therefore the rationale of using biological grafts inusable forms is gaining importance in order to avoid unwanted chronicinflammatory reactions. This review article discusses the need for suchbioprosthetics and the potential role for natural tissues in variousapplications.

The Al2Cu and Al9Co2 intermetallic compounds share structural similarities: they are bothdescribed in terms of coordination polyedra with a tetragonal symmetry and covalent-like bonding occur in both compounds. In this paper, the (001) surface structure of Al2Cu and Al9Co2 is described based on a combined scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), X-ray and ultraviolet photoemission spectroscopy (XPS and UPS) and density functional theory (DFT) study. Surface models are elaborated from stoichiometric ideal compounds, leading to a pure aluminium plane as the surface termination in both cases. The nature of the constitutional defect in Al9Co2 is determined using density functional theory calculations. The influence of the surface atomic density, of the surface composition and of off-stoichiometric effects on the (001) surface structures of Al2Cu and Al9Co2 are discussed.

Cells positioned at the bottom of a Petri dish were exposed, in a home-made plasma source, to pulsed Dielectric Barrier Discharges operated in air in order to investigate the effect of the plasma species on their viability and growth. Processes with different number of pulse, respectively 1,3,9 and 27 pulse, were performed to study the influence on viability and cell growth of two different cell lines, Saos 2 and NHDF. Atmospheric air discharges applied on the two selected cell lines have shown an effect strongly dependent on cell type. At certain doses we have measured increased activity of the NHDF fibroblasts cell line. On the other side, an inhibition of cell adhesion and growth on the Saos 2 osteoblastoma cell line, directly dependent on the plasma doses, was clear. This study shows that by properly tuning the dose of exposure of cells to air plasma it is possible to induce both positive and negative effects on cell growth, that would be useful in several branches of Medicine.

We investigate the vibrational properties of ultrananocrystalline diamond (UNCD) using molecular dynamics simulations. We compare the vibrational spectra of two UNCD models of average grain size 2 and 4 nm with single crystal diamond and an isolated nanodiamond (ND) particle. The vibrational spectra of the ND particle and UNCD models exhibit the effect of phonon confinement as well as undercoordinated atoms at the surface/interfaces. This is further reflected in the specific heat of UNCD models and the ND particle that showed enhancements over that of single crystal diamond. The excess specific heat in UNCD models in comparison to single crystal diamond is found to be maximum at approximately 350 K.

Since a few years, VLS transport is studied not only for homoepitaxial SiC growth but also for SiC selective epitaxial growth (SEG). In this approach, a stacking of silicon and aluminum layers is deposited on the substrate and patterns are created by photolithography. Upon melting, the Al-Si liquid droplets are fed by propane to obtain the SEG of p-doped SiC. In this work, the growth mechanisms were deeper investigated, in particular the influence of the carrier gas (H2 or Ar) and the growth temperature. SEG experiments showed higher growth rates than those measured in the standard configuration (nonselective growth). Moreover, the SiC layers exhibited step-bunched areas characteristic of liquid phase growth but also areas with morphological features due to a disruption of the step-bunching growth mode.

A new family of A-B di-block copolymers based on the amino acid sequences of Nephila clavipes major ampulate dragline spider silk, which have a strong potential for applications in tissue regeneration and drug delivery, was synthesized and characterized. The morphology was assessed by SEM: HBA3 formed fibrillar structure and 2 μm diameter hollow micelles, while HBA4 and HBA6 formed hollow micelles in water solution. The secondary structures of water-cast spider silk-like block copolymer films were assessed by FTIR. The crystallinity was determined by Fourier self-deconvolution of the amide I spectra and confirmed by wide angle X-ray diffraction. Results indicate that the self-assembled morphology and the crystallinity can be varied by changing the length of A-block, and a minimum of 3 A-blocks are required to form β sheet crystalline regions in water-cast spider silk block copolymers. A theoretical model was used to predict the specific reversing heat capacity, Cp(T), which is crucial to the design of smart biomaterials. Excellent agreement was found between the theoretical value and the Cp(T) determined by temperature modulated differential scanning calorimetry. This method can serve as a standard by which to assess the thermal properties for other biologically inspired block copolymers, and then be further applied to control the biological interactions for use in drug delivery and smart biomaterials applications.