Interface induced diffusion

Interface induced diffusion had been identified in a thin film system damaged by electron bombardment. This new phenomenon was observed in Al2O3 (some nm thick)/Si substrate system, which was subjected to low energy (5 keV) electron bombardment producing defects in the Al2O3 layer. The defects produced partially relaxed. The rate of relaxation is, however, was different in the vicinity of the interface and in the "bulk" parts of the Al2O3 layer. This difference creates an oxygen concentration gradient and consequently oxygen diffusion, resulting in an altered layer which grows from the Al2O3/Si substrate interface. The relative rate of the diffusion and relaxation is strongly temperature dependent, resulting in various altered layer compositions, SiO2 (at room temperature), Al2O3 + AlOx + Si (at 500 °C), Al2O3 + Si (at 700 °C), as the temperature during irradiation varies. Utilizing this finding it is possible to produce area selective interface patterning.

Interface Induced Diffusion; Area Selective Interface Patterning

Interface induced diffusion had been identified in thin film system damaged by electron bombardment. This new phenomenon was observed in Al2O3 (some nm thick) / Si substrate system, which was subjected to low energy (5 keV) electron bombardment producing defects in the Al2O3 layer. The defects produced partially relaxed. The rate of relaxation is, however, different in the surrounding of the interface and in the "bulk" parts of the Al2O3 layer. This difference generates an oxygen concentration gradient and consequently oxygen diffusion, resulting in an altered layer which grows from the Al2O3 / Si substrate interface. The relative rate of the diffusion and relaxation is strongly temperature dependent, resulting in various altered layer compositions, SiO2 (at room temperature), Al2O3 + AlOx+Si (at 500o C), Si(at 700o C), as the temperature during irradiation varies. Utilizing this finding it is possible to make area selective interface patterning.

Carbon Nano-Onions Reinforced Multilayered Thin Film System for Stimuli-Responsive Drug Release

Herein, poly (N-(4-aminophenyl) methacrylamide))-carbon nano-onions (PAPMA-CNOs = f-CNOs) and anilinated-poly (ether ether ketone) (AN-PEEK) have synthesized, and AN-PEEK/f-CNOs composite thin films were primed via layer-by-layer (LbL) self-assembly for stimuli-responsive drug release. The obtained thin films exhibited pH-responsive drug release in a controlled manner; pH 4.5 = 99.2% and pH 6.5 = 59.3% of doxorubicin (DOX) release was observed over 15 days. Supramolecular π-π stacking interactions between f-CNOs and DOX played a critical role in controlling drug release from thin films. Cell viability was studied with human osteoblast cells and augmented viability was perceived. Moreover, the thin films presented 891.4 ± 8.2 MPa of the tensile strength (σult), 43.2 ± 1.1 GPa of Young’s modulus (E), and 164.5 ± 1.7 Jg−1 of toughness (K). Quantitative scrutiny revealed that the well-ordered aligned nanofibers provide critical interphase, and this could be responsible for augmented tensile properties. Nonetheless, a pH-responsive and mechanically robust biocompatible thin-film system may show potential applications in the biomedical field.

Asymmetric Hysteresis Loops in Co Thin Films

Asymmetric magnetic hysteresis loops are usually found in exchange bias (EB) systems, typically after field cooling a system below the Néel temperature of an antiferromagnet exchange coupled to a ferromagnet. Alternatively, asymmetric hysteresis loops may occur due to undetected minor loops or in systems with a rotational anisotropy. Here, we report on an exchange bias thin film system MgO(100)/Co/CoO, examined at room temperature, which is far above the blocking temperature, by the magneto-optical Kerr effect (MOKE). While the longitudinal hysteresis loops partly show steps which are well-known from diverse purely ferromagnetic systems, the transverse hysteresis loops exhibit clear asymmetries, similar to exchange biased systems at low temperatures, and unusual transverse magnetization values at saturation. Since minor loops and a rotational anisotropy can be excluded in this case, this asymmetry can possibly be a residue of the exchange bias coupling at lower temperatures.

Robust Metallic Nanolaminates Having Phonon-Glass Thermal Conductivity

Heat transfer phenomena in multilayer structures have gained interest due to their promising use in thermal insulation and thermoelectricity applications. In such systems, nanostructuring has been used to introduce moderate interfacial density, and it has been demonstrated that interfacial thermal resistance plays a crucial role in reducing thermal conductivity κ. Nevertheless, the main constraint for actual applications is related to their tiny size because they are extremely thin to establish appreciable temperature gradients. In this work, by severe plastic deformation process of accumulative roll bonding (ARB), a 250 µm thick Cu-Nb multilayer containing more than 8000 interfaces with periods below 40 nm was obtained, enabling the production of bulk metallic nanolaminates with ultralow κ. Multilayers present an ultralow κ of ∼0.81 W/mK at 300 K, which is 100 times smaller than its Cu-Nb bulk counterpart, and even lower than the amorphous lattice limit for the Cu-Nb thin film system. By using electron diffusive mismatch model (EDMM), we argue that both electrons diffusively scattering at interface and those ballistically crossing the constituents are responsible for heat conduction in the Cu-Nb multilayers at nanoscale. Hence, ARB Cu-Nb multilayers are intriguing candidate materials which can prove avenues to achieve stable ultralow κ thermal barriers for robust applications.

Effect of Addition of PVA/PG to Oil-in-Water Nanoemulsion Kojic Monooleate Formulation on Droplet Size: Three-Factors Response Surface Optimization and Characterization

An oil in water (O/W) nanoemulsion formulation containing kojic monooleate (KMO) in thin film system was developed. Response surface methodology (RSM) was used to optimize and analyzed the effect of three variables, namely concentration of polyvinyl alcohol (PVA) (20–30% w/w), concentration of propylene glycol (PG) (1–10% w/w), and shear rate of high shear homogenizer (3000–9000 rpm) on droplet size as a response, while other compositions remained constant such as KMO (10.0% w/w), Tween 80 (3.19% w/w), castor oil (3.74% w/w), xanthan gum (0.70% w/w), and germall plus (0.7% w/w, PG (and) diazolidinyl urea (and) iodopropynyl butylcarbamate). The optimized KMO nanoemulsion formulation with desirable criteria was PVA (27.61% w/w) and PG (1.05% w/w), and shear rate (8656.17 rpm) with a predicted droplet size (110.21 nm) and actual droplet size (105.93 nm) with a residual standard error (RSE) of less than 2.0% was obtained. Analysis of variance (ANOVA) showed that the fitness of the quadratic polynomial fit the experimental data with a F-value of 65.30, p–value of p < 0.0001, and a non-significant lack-of-fit. The optimized KMO formulation shows the desired criteria of the thin film system and the physicochemical properties (Zeta potential −37.37 mV, PDI 0.13, pH 4.74) and stability at four different conditions indicate its suitability for cosmeceutical applications.