The addition of water results in the higher wear rate of gold compared to experiments performed in the ambient environment (approximately 60% humidity). This higher wear rate in water has been observed with the AFM, Hysitron Triboindenter, and additionally in single pass scratch tests performed with the Taber Shear/Scratch tester. These tests were preformed using silicon nitride cantilevers on the AFM and a conical diamond tip in the Taber instrument. Tests performed in the ambient atmosphere resulted in slightly reduced surface roughness, while much higher wear rate was observed in the wear tests performed in water. Ambient scratch tests produced slightly shallower scratch trenches than wet scratches consistently as a function of the varied normal load. Single scan lines provide valuable information about the mechanisms and progression of the nanoscale wear. The different components of scratch friction are investigated to explore the main contributors to the nanoscale scratching of gold.

We review the current development status of molybdenum borosilicide (Mo-Si-B) alloys for ultra-high temperature applications in air. The assessment of several ingot and powder metallurgy approaches revealed that (i) the presence of a continuous Mo solid solution matrix is mandatory for adequate low temperature toughness and (ii) wrought processing of such alloys at temperatures established for refractory metals requires the presence of an ultrafine (sub-micron) microstructure. Both prerequisites could be fulfilled using mechanical alloying (MA) as the crucial processing step , however, values for the ductile-to-brittle transition temperature (DBTT) below 800°C could not be obtained due to grain boundary embrittlement by Si segregation. First results on the effect of different microalloying additions on a reduction of this segregation exemplified for the Mo solid solution will be presented and discussed.

Studies on Mn, Ni and Co doped ZnO systems have revealed that the RTFM present in these systems can be both intrinsic and extrinsic depending on the choice of TM ion incorporated, technique of preparation and post-synthesis processing. Choice of such a technique that ensures better homogeneity and incorporation of TM ions in the ZnO host, leads to the occurrence of intrinsic, stable and robust RTFM. The air ambient processing eliminates the chances of any metallic cluster inclusions, and instead such TM oxide phases are formed that are non-ferromagnetic. However, post synthesis processing like vacuum annealing of ZnO:Co samples under some situations can give rise to occurrence of extrinsic RTFM. But, this can be overcome by certain additional processing step. ZnO:Co samples with intrinsic RTFM, stable upto 900°C annealing with Curie temperatures in excess of 450°C have successfully been prepared.

This paper reports on the influence of strain rate on the onset of mechanical softening of nanocrystalline gold at room temperature. Micro-tensile testing was performed with applied strain rates on the order of 10−4 s−1 to 10−6 s−1. Our results defined a threshold strain rate, whereby plastic deformation at larger rates was dominated by dislocation processes and at smaller rates by one or more other deformation mechanisms. Furthermore, the data suggested that the critical grain size for inverse Hall-Petch behavior was strain rate sensitive.

Dense and well-adhered CuMn1.8O4 spinel oxide coatings were successfully deposited on Crofer 22 APU stainless steel substrates by a cost effective electrophoretic deposition technique. Coated and uncoated Crofer substrates were oxidized for 120 hours in air at 800°C. A diffusion model was developed for the oxidation of the coated alloys, which predicted para-linear oxidation kinetics. The effective diffusivities in the coating and in the thermally grown oxide were calculated to be 2×10-15 cm2/s and 2.5×10-16 cm2/s respectively, at 800°C. Area specific resistances (ASR) of thermally cycled samples at 800°C did not show a significant difference compared to the isothermally oxidized sample for the same total oxidation time, suggesting good coating adherence. The ASR of the coated alloys is projected to be around 3.8×10-2Ωcm2 after 50000 at 800°C in air, making them excellent candidates for interconnect applications for solid oxide fuel cells operated at 800°C or lower.

The defect structure, transport properties and band structure of the perovskite solid solution SrTi1-xFexO3-δ (STF) can be systematically controlled, over wide limits, by variation in the Fe fraction. In this paper, the authors review recent results which show that STF exhibits model mixed ionic-electronic conducting cathode behavior and extend the composition range investigated to include compositions from SrTiO3 rich values (x = 0.05) to SrFeO3-δ (x= 1). While the majority of the cathodes were prepared as dense films by pulsed layer deposition (PLD), selected compositions were also prepared by thermal inkjet printing. The cathodes were investigated by electrochemical impedance spectroscopy (EIS) as a function of electrode geometry, temperature and oxygen partial pressure. The electrode behavior was found to be controlled by surface exchange kinetics in almost all cases. Values for the surface exchange coefficient, k, were derived and found to be comparable in magnitude to those exhibited by other popular mixed ionic-electronic conductors such as (La,Sr)(Co,Fe)O3, thereby, confirming STF's suitability of as a model mixed conducting cathode material. Surprisingly, the magnitude of k was found to be only weakly dependent on the bulk electronic and ionic conductivities of STF which varied by many orders of magnitude (over nearly five orders of magnitude change in σel) over the x values examined in this study. The observed trends are discussed in relation to the known defect and transport properties of STF.

In this study, we focus on effect of diamond-like carbon (DLC) coating on scaffold for tissue engineering. DLC film was deposited on segmented polyurethane (SPU) scaffold sheet which consists of micro SUP fibers. Structural and compositional effects of the DLC film coating were investigated on cell growth as an investigation of biological response. The surface composition, morphology, structures, and wettability of the DLC film coating was estimated by using X-ray photoelectron spectrometer (XPS), Scanning Electron Microscope (SEM), Ar-laser Raman spectrophotometer (Raman), and contact angle measurement. And then, human umbilical vein endothelial (HUV-EC-C) cells were grown on the DLC coated scaffold sheet. The results presented here suggest that DLC film coating is promising approach to improve biological for tissue engineering.

Aiming to improve thermoelectric properties of half-Heusler (Ma,Mb)NiSn alloys (Ma,Mb = Hf, Zr, Ti), phase equilibria in the (Ma,Mb)NiSn systems were investigated focusing on the phase separation of TiNiSn from ZrNiSn and HfNiSn while (Zr,Hf)NiSn forms all proportion miscible solid solution. Diffusion couples consisting of liquid Sn and solid (Ti,Zr)Ni were used to examine the partitioning behavior which is associated with T-rich and Ti-poor half-Heusler phase separation during the reaction at the interface. Thermal conductivity can be reduced in (Ma0.5,Mb0.5)NiSn and (Ti0.13,Zr0.87)NiSn alloys due to the solid solution effect of M-site substitution. (Ti0.13,Zr0.87)NiSn alloy has high potential as a ecological thermoelectric material.

Routes to porous materials with nanoscale dimensions have been investigated. In the first example presented, porous manganese oxide has been prepared by leaching Ni metal from a nickel-manganese oxide precursor via reduction. Electron microscopy studies have revealed the presence of Ni nanoparticles on the surface, and also embedded within the porous MnO matrix. Magnetic measurements have shown exchange bias between the ferromagnetic Ni nanoparticles and the antiferromagnetic MnO phase. In the second system studied, porous nanostructures of rutile VO2 and corundum V2O3 have been prepared by reduction of amine-templated V2O5−δ nanoscrolls. The porosity of these materials has been probed by electron microscopy, N2 sorption measurements and thermogravimetric analysis.

In this paper, we investigated the effects of the substrates and crystalline orientations on the mechanical properties of Pb(Zr0.52Ti0.48)O3 thin films. The PZT thin films were deposited by sol-gel method on platinized silicon substrates with different types of layer materials such as silicon nitride and silicon oxide. The crystalline orientations of PZT thin films were controlled by combined parameters of a chelating agent and pyrolysis temperature. A nanoindentation CSM (continuous stiffness measurement) technique was employed to characterize the mechanical properties of those PZT thin films. It was observed that (001/100)-oriented films show a higher Young’s modulus compared to films with mixed orientations of (110) and (111), indicating a clear dependence on film orientation. The influence of substrates on the mechanical properties of PZT thin films was also characterized. Finally, no significant influence of the film thickness was found on the mechanical properties of films thicker than 200 nm.

Organic light-emitting diodes (OLED) offer the potential to replace conventional light sources such as incandescent bulbs and fluorescent tubes. The question which thin-film technology is most favorable to produce OLED on an industrial scale is still unanswered. The most established technology for the deposition of small-molecule organic layers is vacuum thermal evaporation. A comparably novel technology is organic vapor phase deposition (OVPD), which offers some unique features in terms of adjustable process parameters such as deposition chamber pressure (P) and substrate temperature (TS ). The impact of these parameters on the morphology of organic single layers as well as on the performance of OLED is mostly unknown. In this work, phosphorescent red OLED were produced with different TS and a strong influence on the device efficiency was found. Atomic force microscopy measurements were conducted to investigate the morphology of the hole injection and hole transport layers of the devices deposited at different TS . In addition to this, the influence of TS and P on the performance of fluorescent blue OLED and the morphology of organic single layers was tested. By varying TS and P for the emission layer only, current efficiencies in the range from 4.3 to 6.8 cd/A were found despite the fact that all devices had the same structure. Atomic force microscopy measurements conducted on organic single layers which were deposited at the same process conditions showed rms values ranging from 1.4 to 57 nm.

The forward voltage drop (Vf ) increase observed in 4H-SiC bipolar devices such as pin diodes due to recombination-induced Shockley stacking fault (SSF) creation and expansion has been widely discussed in the literature. It was long believed that the deleterious affect of these defects was limited to bipolar devices. However, it was recently reported that forward biasing of the body diode of a 10kV 4H-SiC DMOSFET led to similar Vf increases in the body diode I-V curve as well as a corresponding degradation in the majority carrier conduction characteristics as well and this degradation was believed to be due to the creation and expansion of SSFs during the body diode forward biasing. Here we report measurements comparing the influence of similar stressing, along with annealing and current-induced recovery experiments in DMOSFETs and merged pin-Schottky diodes with the previously reported results of these experiments in 4H-SiC pin diodes. The results of these experiments provide sufficient support that the observed degradation in the majority carrier conduction characteristics is the result of SSF expansion.

Experimental results using environmental SEM on intentionally defected fuel particles showed that oxidation induced cracking could lead to the degradation of HTR coated particles. The interpretation proposed for the swelling resulting from cracking can be extended to irradiated nuclear fuels. That is why a new criterion was proposed to defined safe handling of defective fuel in dry storage condition. This criterion defines the time needed to create an oxidized layer thickness leading to significant cracking.

Recent first principles simulations using density functional theory and novel low temperature x-ray diffraction experiments show the existence of a high pressure morphtotropic phase boundary (MPB) in pure PbTiO3. In this paper we apply chemical pressure by substituting smaller atoms in the ABO3 ‘A’ and ‘B’ sites. We find that the ground state of layered PbSnTiO3 (PSnT) is Pmm2, and for rocksalt SnGeTiO3 and PbGeTiO3 is R3m. The polarization of PbSnTiO3 is large (1.13,0,0)C/m2 and is due to the large Born effective charge of the small ‘Sn’ atom. We estimate the d33 for PSnT to be about 2400 pC/N, which is as large as that of currently used relaxor ferroelectrics.

The ion implantation steps used in fabricating field effect transistors in ultrathin (6 to 30 nm) silicon-on-insulator (UTSOI) substrates present many challenges. Deep source/drain (S/D) implants in UTSOI layers are a particular concern, since it can be difficult to implant the desired dose without amorphizing the entire SOI thickness. In a first study, we investigated the effect of implant temperature (20 to 300 °C) on the sheet resistance (Rs) of 28 nm thick SOI layers implanted with As+ at an energy of 50 keV and a dose of 3 × 1015 /cm2, and found Rs values after activation sharply lower for samples implanted at the highest temperature. In a second study, on 8 nm thick SOI layers implanted with As+ at an energy of 0.75 keV and doses in the range 0.5 to 2 × 1015/cm2, the benefits of the elevated implantation temperature were less clear. Explanations for these effects, supported by microscopy, medium energy ion scattering (MEIS), and optical reflectance data, will be discussed.

First-principles calculations by the use of a plane-wave pseudopotential method are performed to investigate intrinsic point defect behavior in TiNi. The results show that TiNi is an antisite type intermetallic compound. The calculated interaction energies between the point defects demonstrate that Ti antisites are attractive to each other whereas Ni antisites are mutually repulsive. The attraction between Ti antisites indicates that excess Ti in TiNi may agglomerate so that a Ti-rich phase can easily precipitate. The repulsion between Ni antisites implies that the excess Ni is of certain solubility in TiNi. This result explains well the asymmetric feature of TiNi field on the binary phase diagram. In order to understand the correlation between the composition dependent elastic modulus and martensitic transformation (MT) temperature, the elastic moduli critical to MT, i.e., c′ and c 44, are calculated as a function of the composition of the off-stoichiometric TiNi and a series of ternary TiNi-X alloys, by the use of exact muffin-tin orbital method in combination with coherent potential approximation. It turns out that, generally speaking, the early transition metal (TM) alloying elements in the periodic table increase c′ but decrease c 44; the middle ones increase both c′ and c 44, whereas the late ones decrease c′ but increase c 44. An examination of the theoretical composition dependent elastic modulus and the experimental MT temperature shows that the MT temperature is more sensitive to the variation of c 44 than to that of c′.

A new extractant for the separation of actinide(III) and lanthanide(III), bis(o-trifluoromethylphenyl)phosphinic acid (O-PA) was synthesized. The synthetic route employed mirrors one that was employed to produce the sulfur containing analog bis(o-trifluoromethylphenyl)dithiophosphinic acid (S-PA). Multinuclear NMR spectroscopy was used for elementary characterization of the new O-PA derivative. This new O-PA extractant was used to perform Am(III)/Eu(III) separations and the results were directly compared to those obtained in identical separation experiments using S-PA, an extractant that is known to exhibit separation factors of ∼100,000 at low pH. The separations data are presented and discussed in terms comparing the nature of the oxygen atom as a donor to that of the sulfur atom in extractants that are otherwise identical.

Electrochemical studies such as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 (N06022) in 1M NaCl solutions at various pH values from acidic to neutral at 90°C. All the tested material was wrought Mill Annealed (MA). Tests were also performed in NaCl solutions containing weak organic acids such as oxalic, acetic, citric and picric acids.

Results show that the CR of Alloy 22 was significantly higher in solutions containing oxalic acid than in solutions of pure NaCl at the same pH. Citric and Picric acids showed a slightly higher CR, and Acetic acid maintained the CR of pure chloride solutions at the same pH. Organic acids revealed to be weak inhibitors for crevice corrosion. Higher concentration ratios, compared to nitrate ions, were needed to completely inhibit crevice corrosion in chloride solutions.

Results are discussed considering acid dissociation constants, buffer capacity and complex formation constants of the different weak acids.

We have measured the yield strength of gold nanowire forests with mean diameter 30, 60 and 70 nm fabricated by electro-deposition into porous alumina templates. All nanowire sizes showed yield strengths much greater than expected from polycrystalline gold specimens with the 30 nm specimens having a yield stress in excess of 1.4 GPa. We found no significant work hardening at plastic strains up to 30%. The strength of the nanowires as a function of wire diameter follows the same trend as has been reported for the compression strength of larger gold pillars reported in the literature. TEM observations of deformed wires are consistent with mechanisms of dislocation induced deformation.

We have investigated the effect of nanometric grain sizes on Microstructural, electrical-, magneto-transport and magnetic behaviors in nanocrystalline Nd0.67Sr0.33MnO3 CMR manganites. Three nanocrystalline powders of Nd0.67Sr0.33MnO3 were synthesized through chemical route “Pyrophoric Reaction Process” and calcined for 5 hrs at calcinations temperature (TCal = 650°C, 750°C, and 850°C). XRD patterns indicate that all the synthesized powders have pseudo-cubic perovskite structure without any secondary impurity phase. Using Debye Scherrer formula we calculated the crystallites size for three nanocrystalline Nd0.67Sr0.33MnO3 powders (∼ 30, 40, and 54 nm for TCal = 650°C, 750°C, and 850°C respectively). TEM micrographs show that the average particle sizes are in nanometric regime (ψ ∼ 30–50 nm). In AC susceptibility and resistivity measurement we observed that there is an almost constant Curie temperature (TC) has value around 240 K and gradual decrease of metal-insulator transition temperature (TP) (from 200-129 K) with decrease of TCal. The magneto resistance of ultra fine nanoparticles increases with grain sizes. Highest magnetoresistance observed ∼ 24 for Nd0.67Sr0.33MnO3 with TCal = 850°C. Experimental results revels, the effect of nanometric grain sizes has an important impact in magnetic properties and magneto-transport behaviors.