Study of microstructure and nanomechanical properties of Zr films prepared by pulsed magnetron sputtering

The present work studies the effect of substrate temperature on the growth characteristics of zirconium films prepared by pulsed magnetron sputtering. Formation of α-phase of zirconium was observed in the temperature range 300-873 K. X-ray diffraction of Zr films revealed predominantly [0 0 1] texture. It is noticed that crystallite size increases with increasing substrate temperature. Hexagonal shaped crystallites seem to grow along the surface normal of the substrate for the films deposited at 773 K. Nanoindentation measurements showed that the hardness of the films is in the range 6-10 GPa. The scratch test indicated that the films deposited at higher substrate temperatures had excellent bonding with the substrate and no significant critical failure was noticed up to an applied load of 20 N.     

Topography and friction properties of macromolecular thin films using atomic-force-microscopy technology

Applied Physics A - The research work in this letter is on the microtribological properties of poly(ether ketone ketone) (PEKK) and sulfonated PEKK (S-PEKK) thin films. Polystyrene (PS) was used as...     

Lamellar structure and nanomechanical properties of quasicrystalline Al-Cu-Fe alloys

The kinetics of structural phase transformations in quasicrystal-forming Al-Cu-Fe alloys with compositions in the region of stability of the icosahedral (i) phase has been investigated. It has been shown that, depending on the development of metastable transformations i → pentagonal phases P1 and P2, a homogeneous lamellar structure (i + P1 + P2) or a polygrain i-phase is formed in the alloys. The P-h diagrams obtained upon nanoindentation, atomic force microscopy, and scanning electron microscopy of indentations have demonstrated signs of elasto-plastic deformation of the alloys with lamellar and polygrain icosahedral structures. It has been found that, in contrast to the polygrain icosahedral alloys with a normal size effect of nanoindentation, the alloys with a lamellar structure are characterized by a nonmonotonic dependence of the hardness (H) on the maximum load (P _max) and exhibit the effect of strain hardening in the range of loads 50 mN ≤ P _max < 500 mN. The strain hardening is considered as the result of resistance exerted by boundaries of the lamellar structure to the development of plastic deformation.     

Thermal,surface, nanomechanical and electrical properties of epoxidized natural rubber (ENR-50)/ polyaniline composite films

A new composite material from epoxidized natural rubber (ENR-50) and polyaniline have been successfully prepared. Aniline which was polymerized in the presence of dodecylbenzene sulfonic acid (DBSA), then added to ENR-50 for the preparations of ENR-50/Pani.DBSA composite films. The hydrogen bonding which contribute to the formation of ENR-50/Pani.DBSA composites was observed in FT–IR, UV–Visible and DSC. It showed hydrogen bonding interactions between the epoxy groups in ENR-50 and the amine groups in Pani.DBSA. The morphologies of the prepared materials were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and conductivity measurements revealed that the percolation threshold is at 2.5 w% of Pani.DBSA content. Atomic force microscopy (AFM) micrographs showed that ENR-50 with 5 wt% Pani.DBSA addition has the lowest surface roughness. In addition thermogravimetric analysis indicates improved thermal stability at low Pani.DBSA content. DSC measurements revealed that T_g value increases with increasing Pani.DBSA, indicating that the formation of homogenous composite material. Nanoindentation results show that the hardness (H) and Young's modulus (E_s) increased with higher addition of Pani.DBSA polymer.     

Raman studies of Pd-C nanocomposites

The results of studying palladium-carbon (Pd-C) nanocomposites using Raman spectroscopy are presented. This method has been used for studying samples having various palladium content, prepared by a one-step Physical Vapour Deposition (PVD) process and a Chemical Vapour Deposition (two-step PVD/CVD) process using different process parameters. For samples obtained by PVD, the vibration bands characteristic of C₆₀ fullerene molecules were observed in the spectra, whereas for layers obtained by PVD/CVD, the Raman spectra displayed mainly D and G bands characteristic solely of the prescence of graphite-like layers’ vibrations. The analysis of the obtained Raman spectra reveals that its shape is affected by many parameters including type of substrate, temperature, and the percentage content of Pd in the studied layer. The quantitative analysis of spectra for layers obtained using the PVD/CVD process shows a difference in the relative intensity of bands D and G, reflecting the different degrees of amorphisation in the investigated nanocomposites.     

Eucalyptus nitens: nanomechanical properties of bark and wood fibers

In this study, Eucalyptus nitens species was nano-characterized to determine variability in nanomechanical properties within the cellular ultra-structure between the bark and wood fibers. Three factors, including site (2 levels), family (2 levels) and fiber type (bark and wood) were analyzed using three response variables, including the elastic modulus (E), hardness (H) and ductility ratio (E/H) in the middle lamella (ML) and the cell wall within the S2 layer. The results indicated significant differences for E _S2 and H _S2 when comparing fiber types: E _S2≈12.52 GPa and H _S2≈0.31 GPa for wood fiber and E _S2≈10.81 GPa and H _S2≈0.26 GPa for bark fiber. There is not statistically significant difference in ductility ratio (E/H) in S2 and ML between fiber types. These results indicate that bark and wood fibers can be used together or separately in the development of new composite materials and engineering products.     

Effects of post-annealing on the structural and nanomechanical properties of Ga-doped ZnO thin films deposited on glass substrate by rf-magnetron sputtering

In this study, the effects of post-annealing on the structure, surface morphology and nanomechanical properties of ZnO thin films doped with a nominal concentration of 3 at.% Ga (ZnO:Ga) are investigated using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) and nanoindentation techniques. The ZnO:Ga thin films were deposited on the glass substrates at room temperature by radio frequency magnetron sputtering. Results revealed that the as-deposited ZnO:Ga thin films were polycrystalline albeit the low deposition temperature. Post-annealing carried out at 300, 400 and 500 °C, respectively, has resulted in progressive increase in both the average grain size and the surface roughness of the ZnO:Ga thin film, in addition to the improved thin films crystallinity. Moreover, the hardness and Young's modulus of ZnO:Ga thin films are measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) option. The hardness and Young's modulus of ZnO:Ga thin films increased as the annealing temperature increased from 300 to 500 °C, with the best results being obtained at 500 °C.     

Effect of strain relaxation of oxidation-treated SiGe epitaxial thin films and its nanomechanical characteristics

In this study, we examined the effect of high-temperature oxidation treatment on the SiGe epitaxial thin films deposited on Si substrates. The X-ray diffraction (XRD), atomic force microscopy (AFM), and nanoindentation techniques were employed to investigate the crystallographic structure, surface roughness, and hardness (H) of the SiGe thin films, respectively. The high-temperature oxidation treatment led to Ge pileup at the surface of the SiGe thin films. In addition, strain relaxation occurred through the propagation of misfit dislocations and could be observed through the cross-hatch pattern (800-900 °C) and SiGe islands (1000 °C) at the surface of the SiGe thin films. Subsequent hardness (H) measurement on the SiGe thin films by continuous penetration depth method indicated that the phenomenon of Ge pileup caused a slightly reduced H (below 50 nm penetration depth), while relaxation-induced defects caused an enhanced H (above 50 nm penetration depth). This reveals the influence of composition and defects on the structure strength of high-temperature oxidation-treated SiGe thin films.     

Measurement of nanomechanical properties of biomolecules using atomic force microscopy

The capabilities of atomic force microscopy (AFM) have been rapidly expanding beyond topographical imaging to now allow for the analysis of a wide range of properties of diverse materials. The technique of nanoindentation, traditionally performed via dedicated indenters can now be reliably achieved using AFM instrumentation, enabling mechanical property determination at the nanoscale using the high spatial and force resolutions of the AFM. In the study of biological systems, from biomolecules to complexes, this technique provides insight into how mesoscale properties and functions may arise from a myriad of single biomolecules. In vivo and in situ analyses of native structures under physiological conditions as well as the rapid analysis of molecular species under a variety of experimental treatments are made possible with this technique. As a result, AFM nanoindentation has emerged as a critical tool for the study of biological systems in their natural state, further contributing to both biomaterial design and pharmacological research. In this review, we detail the theory and progression of AFM-based nanoindentation, and present several applications of this technique as it has been used to probe biomolecules and biological nanostructures from single proteins to complex assemblies. We further detail the many challenges associated with mechanical models and required assumptions for model validity. AFM nanoindentation capabilities have provided an excellent improvement over conventional nanomechanical tools and by integration of topographical data from imaging, enabled the rapid extraction and presentation of mechanical data for biological samples.     

Effect of nitrogen doping on nanomechanical and surface properties of silicon film

The effect of nitrogen ion implantation on the nanomechanical properties of single crystal Si was evaluated by means of a conventional Vickers indentation and nanoindentation tests. The images of Si surfaces before and after nitrogen implantation were observed and their average surface roughnesses were measured by an atomic force microscope (AFM), while the changes in the morphology and microstructure of the single crystal Si by N implantation were examined by field emission scanning electron microscope (SEM) and X-ray diffractometer (XRD). In addition, the hydrophilic/hydrophobic surface property of the N-doping Si film was determined from the measurement of water contact angle by the sessile drop technique. Furthermore, the effects of the doping energy on the surface contact angle and the surface roughness and the Vickers hardness of the film are also investigated.     

Controlling statistical properties of a Cooper pair box interacting with a nanomechanical resonator

We investigate the quantum entropy, its power spectrum, and the excitation inversion of a Cooper pair box interacting with a nanomechanical resonator, the first initially prepared in its excited state, the second prepared in a “Schrödinger-cat” state. The method employs the Jaynes–Cummings model with damping, with different decay rates of the Cooper pair box and different ranges of detuning, going from resonant to off-resonant cases, including time dependent detunings. Concerning the entropy, it is found that the time dependent detuning turns the entanglement more stable in comparison with previous results in the literature. With respect to the Cooper pair box excitation inversion, while the presence of detuning destroys the collapses and revivals, it is shown that convenient time dependent detunings recover such effects in a nice way.     

Size effect on nanomechanical properties of ZnO cones using in situ transmission electron microscopy

Nanoscale fracture and strain-induced structure variation of ZnO nanocones are determined using in situ transmission electron microscopy compression experiments. For the single-crystalline nanocones with diameters of 100–300 nm, the Young's modulus is in the range of 7.7–48 GPa and the ultimate tensile strength is in the range of 2.4–4.3%. The Young's modulus and tensile strength increase with decreasing diameter. Here, we report the nanogenerator of ZnO nanocones can be used mechanical energy to output 90 nW/mm².     

Macrospin tunneling and magnetopolaritons with nanomechanical interference

We theoretically address the quantum dynamics of a nanomechanical resonator coupled to the macrospin of a magnetic nanoparticle by both instanton and perturbative approaches. We demonstrate suppression of the tunneling between opposite magnetizations and destruction of magnetopolaritons (coherent magnetomechanical oscillations) by nanomechanical interference. The predictions can be verified experimentally by a molecular magnet attached to a nanomechanical bridge.     

Optical properties of ZnTe films

Optical properties of p-type ZnTe films, deposited by hot-wall vacuum evaporation, were studied extensively in the range of incident photon energy 0.6–2.6 eV. Variations of refractive index, absorption and extinction coefficients with incident photon energy are reported in this communication.     

Transport properties of Chitosan-Amikacin films

The transport properties of films based on chitosan and a drug have been studied, and sorption and diffusion characteristics of the films have been examined. The calculated diffusion coefficients and the abnormal kinetic curves of amikacin release have been discussed. An analysis of the obtained data showed that the process of drug transport from chitosan films deviated from the classical Fick’s laws due to structural changes in the polymer matrix induced by its chemical modification because of interaction with the drug.     

Optical and electrical properties of tin-dioxide films

Summary The electro-optical properties of thin SnO₂ films are analysed in relation to different experimental deposition conditions. Heating tests have been performed on the samples; the results are discussed.

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Riassunto Si analizza l'influenza di differenti condizioni sperimentali di deposizione sulle proprietà elettro-ottiche di film sottili di SnO₂. Si riportano i risultati di prove di invecchiamento condotte mediante cicli termici.

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Резюме Анализируется влияние различных экслериментальных условий напыления на электрические и оптические свойства тонких пленок диоксида олова. Проводятся испытания с использованием темических циклов. Обосуждаются полученные резльтаты.

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This work has been performed in the framework of activities of the ?Progetto Finalizzato Energetica? supported by the C.N.R.     

Structure and magnetic properties of FeCoN films

We obtained crystals of RuS₂ doped with ⁵⁷Fe from a Bi melt and determined the EPR hyperfine structure corresponding to ⁵⁷Fe³⁺ in low-spin configuration. In crystals that were doped with both Fe and Cr an increase of the Fe³⁺ resonance and a simultaneous decrease of the Cr³⁺ resonance occurred by IR irradiation and revealed the same wavelength dependence. Compared with as-grown crystals the iron-doped crystals turned out to have a rather high electrical resistivity of about 10⁴Omega cm at room temperature. For these iron-doped crystals two different activation energies of 0.04 eV and 0.35 eV of the free charge carriers (electrons) were determined from measurements of the electrical conductivity in the range of 94 K and 294 K. Received: 29 July 1996/Accepted: 13 November 1996