Using a new multidimensional contact mechanics system, the normal and tangential elastic contact stiffnesses of six bulk materials with Poisson’s ratios ranging from 0.17 to 0.42 were measured. It is shown that the experimentally measured tangential to normal stiffness ratio can be described as a function of the bulk Poisson’s ratio of the material as predicted by Mindlin. The technique shows a high sensitivity to variations in Poisson’s ratio, suggesting that the technique is a viable means for measuring the Poisson’s ratio of new novel materials. The technique was subsequently applied to two metal film–glass substrate systems. Experimental observations indicate that even when Poisson’s ratio mismatch between the film and the substrate is large, the technique yields appropriate bulk values for the Poisson’s ratio of the film. The experimental details and apparatus are introduced and described.

Printed organic circuits have the potential to revolutionize the spread of electronic applications. This will be enabled by inexpensive and fast fabrication with printing techniques using soluble organic materials. Two main challenges have to be mastered on the way towards printed electronics. First, the development of stable transistors and an adapted chip design for organic materials, and second, the development of a reliable fabrication process. We present our results on high performance polymer transistors, mainly based on poly-3alkylthiophene (P3AT) as semiconducting material. Fast circuits up to 200 kHz and stable circuits with operation lifetimes of more than 1000 h under ambient conditions without any encapsulation are shown. We also report on a fully printed, all organic ring oscillator.

C-axis oriented lithium niobate (LiNbO3) films were deposited by pulsed-laser deposition on silicon using a transparent conducting interlayer of aluminum (Al)-doped zinc oxide (ZnO). Only two x-ray diffraction reflections corresponding to (006) and (0012) planes of LiNbO3 were observed in the films deposited at a 100-mTorr oxygen pressure and a 450–500 °C substrate temperature. Presence of sharp modes corresponding to E(TO) and A(LO), and absence of any superfluous peaks mainly around 900–905 cm−1 in the Raman spectra confirmed the formation of textured LiNbO3 film. Measured value of direct current and alternate current (AC) conductivities and dielectric constant are 8.6 × 10-12 Ω−1cm-1, 1.16 × 10-6 Ω−1cm-1, and 29.3, respectively, at room temperature. Behavior of dielectric constant and AC conductivity with frequency and temperature are close to the reported single-crystal data.

A method to prepare samples for four point bend testing is reported in this paper. The traditional method of sample preparation involves time-consuming steps of sawing with a diamond saw followed by polishing with fine grit to remove the roughness of the sidewall. The new method uses cleaving along the 〈100〉 crystallographic direction, which renders smooth surfaces and eliminates the polishing steps. Load–displacement curves comparing polished versus cleaved samples show that the new technique provides improved results. Elimination of fracture-inducing defects is the primary benefit of this method, which also leads to data with tighter distributions.

A new Mg-based bulk amorphous alloy (i.e., Mg65Cu25Gd10) has successfully been developed by Men and Kim [H. Men and D.H. Kim, J. Mater. Res. 18, 1502 (2003)]. They showed that this alloy exhibits significantly improved glass-forming ability (GFA) in comparison with Mg65Cu25Y10 alloy. However, this improved GFA cannot be indicated by the supercooled liquid region ΔT and the reduced glass-transition temperature Trg. As shown in the current comment, the new parameter γ, Tx/(Tg + Tl) defined in our recent papers [Z.P. Lu and C.T. Liu, Acta Mater. 50, 3501 (2002); Z.P. Lu and C.T. Liu, Phys. Rev. Lett. 91, 115505 (2003)] can well gauge GFA for bulk metallic glasses, including the current Mg-based alloys.

The approach developed for the microindentation of layered elastic solids was adapted to analyze atomic force microscopy probing of ultrathin (1–100 nm-thick) polymer films on a solid substrate. The model for analyzing microindentation of layered solids was extended to construct two- and tri-step graded functions with the transition zones accounting for a variable gradient between layers. This “graded” approach offered a transparent consideration of the gradient of the mechanical properties between layers. Several examples of recent applications of this model to nanoscale polymer layers were presented. We considered polymer layers with elastic moduli ranging from 0.05 to 3000 MPa with different architecture in a dry state and in a solvated state. The most sophisticated case of a tri-layered polymer film with thickness of 20–50 nm was also successfully treated within this approach. In all cases, a complex shape of corresponding loading curves and elastic modulus depth profiles obtained from experimental data were fitted by the graded functions with nanomechanical parameters (elastic moduli and transition zone widths) close to independently determined microstructural parameters (thickness and composition of layers) of the layered materials.

Understanding the hardening response of small volumes is necessary to completely explain the mechanical properties of thin films and nanostructures. This experimental study deals with the deformation and hardening response in gold and copper films ranging in thickness from 10 to 400 nm and silicon nanoparticles with particle diameters less than 100 nm. For very thin films of both gold and copper, it was found that hardness initially decreases from about 2.5 to 1.5 GPa with increasing penetration depth. Thereafter, an increase occurs with depths beyond about 5–10% of the film thickness. It is proposed that the observed minima are produced by two competing mechanisms. It is shown that for relatively deep penetrations, a dislocation back stress argument reasonably explains the material hardening behavior unrelated to any substrate composite effect. Then, for shallow contacts, a volume-to-surface length scale argument relating to an indentation size effect is hypothesized. A simple model based on the superposition of these two mechanisms provides a reasonable fit to the experimental nanoindentation data.

A nanostructured surface layer was formed on an Inconel 600 plate by subjecting it to surface mechanical attrition treatment at room temperature. Transmission electron microscopy and high-resolution transmission electron microscopy of the treated surface layer were carried out to reveal the underlying grain refinement mechanism. Experimental observations showed that the strain-induced nanocrystallization in the current sample occurred via formation of mechanical microtwins and subsequent interaction of the microtwins with dislocations in the surface layer. The development of high-density dislocation arrays inside the twin-matrix lamellae provides precursors for grain boundaries that subdivide the nanometer-thick lamellae into equiaxed, nanometer-sized grains with random orientations.

In this paper we present a new method of the rapid construction of magnetic phase diagrams in a temperature-composition space, using magneto-optic imaging with an indicator film technique (MOIF). The method is applied for mapping the diagram for the La1–xCaxMnO3 colossal magneto-resistive oxide, using the spread films deposited on a SrTiO3 substrate. The constructed magnetic diagram is in a good agreement with data on uniform films and bulk crystals of this system. The MOIF study of transitions under cooling and heating has revealed the formation of a non-magnetic phase in the area of temperatures from 5 K to 57 K and compositions from x = 0 to x = 0.5.

Gallium nitride (GaN) has been synthesized by reacting gallium trichloride with ammonia (NH3) at low temperatures ranging from 500 to 1000 °C for 12 h. X-ray diffraction, transmission electron microscopy, infrared, and Raman backscattering spectra revealed that the synthesized GaN powder consists of single-phase nano-sized crystallites with the wurtzite-type structure. The average size of the crystals decreases with the reaction temperature from approximately ∼63 nm at 1000 °C to ∼5 nm at 500 °C. GaOCl and ϵ–Ga2O3 are the intermediate products during synthesis of the GaN. Characteristic shifts of the Raman peaks are associated with the change in crystal size. The band-edge emission of GaN at 361 nm was observed on room temperature photoluminescence spectra exclusively for the sample synthesized at 1000 °C, while a new and broad emission band appeared with the center ranging from 827 to 765 nm for the samples synthesized between 500 and 800 °C.

Materials with preferred orientation exhibit unique properties that are frequently improved in comparison with those that are randomly oriented. Optical waveguide devices require high-quality single-crystal–like thin films because of their low optical propagation loss and their near–single-crystal properties. The growth mechanisms of textured films on non-lattice matched amorphous substrates, such as glass, are different from those on single-crystal substrates or the surface of a metal electrode. In this study, highly (100) oriented Pb(Zr,Ti)O3 PZT films were grown on an amorphous substrate by means of the sol-gel multicoating method, using lanthanum nitrate as a buffer layer. The lanthanum nitrate buffer layer was also very effective as a diffusion barrier against Pb-Si interdiffusion. The electrooptic properties of the PZT films were markedly enhanced when their orientation was adjusted to the (100) direction.

Understanding the tribological, mechanical, and structural properties of an inorganic and organic dielectric layer in the chemical mechanical planarization (CMP) process is crucial for successful evaluation and implementation of these materials with copper metallization. Polishing behaviors of different carbon- and fluorine-doped silicon dioxide (SiO2) low dielectric constant materials in CMP process are discussed in this paper. Films were deposited using both chemical vapor deposition and spin-on method. Carbon and fluorine incorporation in the Si–O network weaken the mechanical integrity of the structure and behave differently in slurry selective to SiO2 films. Mechanical properties of the films were measured using depth-sensing nanoindentation technique, and it was found that undoped SiO2 film has the highest and spin-on carbon-doped oxide films have the lowest hardness and modulus values. Wear behavior of the doped SiO2 is studied in a typical SiO2 CMP environment, and results are analyzed and compared with those of the undoped SiO2 films. Coefficient of friction and acoustic emission signals have significant effect on the polishing behavior. Surface of the films are investigated before and after polishing using atomic force microscopy. Roughness and section analysis of the films after polishing show the variation in wear mechanism. Validation of Preston’s equation is discussed in this study. Additionally, different wear mechanisms are presented, and a two body abrasion model is proposed for the softer films.

This research investigates the microstructure and mechanical properties of ultrafine WC-10Co cemented carbides fabricated by an electric-discharge compaction (EDC) process, from powder synthesized by a spray-conversion process (SCP). Due to a short holding time during EDC, a grain size as small as 120 nm can be achieved. We also found that dispersion of pores in WC-Co cemented carbides may contribute to fracture toughness, besides the bridging ligament mechanism.

Phase transformations in near-equiatomic TiNi shape memory alloy thin films were studied, and the phase fraction evolutions were quantitatively correlated to the stress and resistivity of the films. TiNi thin films with compositions of 50.1, 51.1, and 51.7 at.% Ti all exhibited transformation temperatures between 65 and 100 °C, low residual stresses at room temperature (RT), and high recoverable stresses, thus making them suitable for microactuators in microelectromechanical systems. Low residual stresses at RT, less than 50 MPa, can be obtained even when only a small quantity of martensite, less than 30%, is present. Phase fraction evolution during complete thermal cycles (heating and cooling) was studied using elevated temperature x-ray diffraction, combined with quantitative Rietveld analysis. R-phase always appeared in these near-equiatomic TiNi thin films during cooling but did not have a noticeable effect on the stress–temperature hysteresis curves, which mainly depend on the phase fraction evolution of martensite. On the other hand, the occurrence of R-phase determined the variation of film resistivity. Martensite, austenite, and R-phase coexisting within a single grain were observed using transmission electron microscopy.

Techniques for manufacturing organic electronic devices [organic light-emitting diodes (OLEDs), photovoltaic cells, transistors, and solid-state memory] are reviewed and analyzed with respect to cost and market fitness in comparison to competitive approaches based on silicon electronics. The conclusions are (i) OLED displays will be successful using infrastructure largely borrowed from liquid crystal displays, because they provide fundamental customer value not dependent on lower cost; (ii) OLEDs for general lighting and organic–inorganic hybrid photovoltaic cells currently confront substantial barriers in cost and efficiency, but solutions appear feasible and would lead to very large volume businesses; (iii) organic crossbar memories are promising, but require innovations in driver architecture and interconnection; and (iv) organic transistors have not yet found a viable major market, but have great promise for highly customized, small-volume product runs using digital patterning techniques.

In this article, we present a study of a new glass system: lead–germanium–tellurite glasses in the form of 0.05K2O–0.1ZnO–0.1BaO–0.2PbO–xGeO2–(0.55 - x)TeO2 with x = 0.1, 0.2, 0.3, 0.4, 0.5, and 0.55. Differential temperature analysis of this glass system shows that increasing GeO2 content raises the glass transition temperature (Tg) and suppresses the crystallization tendency in a large temperature range from Tg to the glass melting temperature. The maximum vibrational frequency is intermediate between germanate and fluoride glasses, in the range of 750 cm−1 to 820 cm−1. Subsequently, Optical absorption, photoluminescence, and upconversion fluorescence were measured for Yb3+, Er3+ co-doped lead–tellurium–germanate glasses. It was found that the full width at half-maximum of the fluorescence spectrum at 1534 nm decreases and the measured radiative lifetime increases with the replacement of TeO2 by GeO2. Excitation at 976 nm into the glass system leads to an intense green emission and a relatively weak red emission. With the addition of GeO2, the increase of red fluorescence and the decrease of green emission in intensity are due to the increase of nonradiative transition rates between the 4S3/2 and 4F9/2 states of Er3+ ions. The quadratic dependence of the green and red emissions on excitation power indicates that two-photon absorption process occurs in this glass system excited at 976 nm.

A simple method has been proposed for an independent determination of the frame compliance Cf and the area function of a Berkovich indenter. Cf was determined from the unloading compliance of very large indentations in four test materials (fused silica, silicon nitride, high-carbon steel, and copper-zinc alloy) with known elastic properties, following the Oliver–Pharr method by assuming the ideal shape of Berkovich indenter. For a specific value of Cf (= 0.3 nm/mN in our case) all the specimens showed an hc (contact depth)-independent modulus, which agreed well with the expected value when the pile-up effect was taken into account. The contact area A(hc) was then estimated using fused silica as the standard specimen, according to two different procedures, i.e., the Oliver–Pharr method and the Field–Swain method. Both methods gave almost identical area functions over the whole range of the measurement. It was also found that such area functions can be described by two separate equations: A = 2πRehc for hc < Δh and A = g(hc + Δh)2 for hc ⩾ Δh, where Re is the effective tip radius, Δh the truncation depth, and g the geometrical factor for a Berkovich indenter. Based on the spherically truncated cone model, a simple procedure is presented to determine all these parameters from the analysis of a multiple partial unloading P-h curve.

Bulk nanocrystalline body-centered cubic- (bcc) (Fe,Co) alloy with high saturated magnetization and good soft magnetic properties was synthesized by the simple process of casting and annealing for the glass-type Fe62.8Co10B13.5Si10Nb3Cu0.7 alloy. It crystallizes through two exothermic reactions. The cylindrical glassy rod with the diameter of 1.5 mm was produced by copper mold casting. The subsequent annealing at the temperature higher than that of the first exothermic peak causes the formation of bcc-(Fe,Co) nanocrystalline with particle sizes between 10 and 15 nm. The bcc-(Fe,Co) alloy rods exhibit good soft magnetic properties of 1.35 T for saturation magnetization and 5 A/m for coercive force.

Transparent Pb(Zn1/3Nb2/3)O3–(Pb1-xLax)(Zr1-yTiy)O3 (PZN–PLZT) ferroelectric ceramics have successfully been prepared by hot-pressed sintering in oxygen atmosphere. Uniform cylindrical samples with diameter as large as Φ = 50 mm can readily be obtained. X-ray analysis and scanning electron microscopy experiments showed a pure perovskite phase, thin grain boundaries, and uniform dense microstructures. Very good transparency was reached for wavelength from near ultraviolet to infrared. The dielectric constant was also measured as a function of temperature and frequency. Some novel phenomena such as good piezoelectric and electro-optical properties have been observed.

CdSe magic-sized nanoclusters were synthesised at relatively low temperatures (90–150 °C) in the organometallic raw material solution by a very simple method. The variation process from nanoclusters to nanocrystals has been determined using the microreactor, and it was found that these nanoclusters could increase the CdSe nuclei number and product yield in the microfluidic reactor method. Meanwhile, the microreactor shows the advantage for studying the nanocrystal-growth process due to the precise time and temperature control and high reproducibility.