Recent Patents on Nanotechnology - Volume 10, Issue 1, 2016

Background: Graphene is a new type of two-dimensional crystal material, and its single atomic layer structure shows many excellent physical and chemical properties such as large specific surface area, good electrical conductivity and high Young's modulus. However, few relevant patents to the topic have been reviewed and cited. This paper mainly deals with the methods of the preparations of graphene and graphene applications in NEMS sensors, NEMS devices, optics, energy storage, and biomedical fields. Methods: At present, compared with the less effective experimental research method, the numerical simulation method has become an effective research approach. Molecular dynamics is widely used in the numerical simulation calculation. Molecular dynamics can simulate the change process of graphene in real environments. Molecular dynamics reveals the microscopic deformation under the action of external load. Results: The analysis process of two structures is mainly through the external stretched or compressed force exerted on the graphene. The Young’s modulus of the simulated graphene is about 0.86TPa. The simulated tensile strength is about 121GPa.The resonance frequency of graphene resonators can be changed by the tension of both ends of the beam. As the initial strain increases, the resonance frequencies also increase. For very small initial axial -strain, the tunable range reached above several hundred gigahertz. As the initial axial -strain of graphene increased, the tunable range decreased. Conclusion: Due to the unique properties and potential applications of graphene, it has aroused an extensive research boom in nano science world. Graphene is considered as one of the most promising materials of next generation electronic devices.

Background: Traditional organic friction materials are difficult to adapt to people’s growing technical requirements for stability, safety, comfort and environmental protection in the braking process. With the rapid development of nanotechnology, the brake’s organic friction materials meet new opportunities. This article aims to review the research progress of organic friction materials that have applied nanotechnology. Methods: The research progress of nano organic friction materials was reviewed from four aspects in this article. Firstly, this article outlined the development history of friction materials. Secondly, two preparation methods of the nano organic friction material were summarized as by nano modifying of matrix material and by adding nanoparticles into friction material. Thirdly, it was indicated that the nano organic friction material has generally better mechanical, physical properties and tribological performance than traditional organic friction materials. And the main factors that affect the friction and wear performance were analyzed. Finally, the main existing problems in this field were summarized. Results: It was pointed out that the nano organic friction material may be an important developing trend of friction materials. It was also pointed out that the dispersion of nanoparticles must be a key process during preparation. What is more, the improvement mechanisms of performance by nano modifying were explained. And it was considered at the end that the functional friction material with magnetism or self-adsorption may be a leading developoing direction of nano organic friction materials in the future. Conclusion: The findings of this review confirm the excellent performance of nano organic friction materials. It is concluded that the development of a new functional friction material by using the special effect of nanoparticles will be an important developing trend. Few relevant patents to the topic have been reviewed and cited.

Background: Metal oxide nanostructures are being investigated widely due to their strong optical absorption, efficient photoluminescence, abundant of availability and structural stability which lead them as a possible substitute of Si based solar cells and many optoelectronic and sensor devices. Due to their non-toxic nature they are supposed to be promising materials for drug delivery and medical research. Among several metal oxides, cupric oxide (CuO) is being investigated nowadays due to their high transparency and visible luminescence. It is a p-type semiconductor of band gap varying from 1.3 eV to 2.1 eV depending of the structure and process of fabrication. This low band gap of CuO nanostructures leads its application in photoconductive and photothermal applications. This leads rigorous investigations on CuO nanostructures. Methods: A simple wet chemical methods has been used to synthesize CuO bipods. Predetermined amount of Copper sulphate penta-hydrate (CuSO4, 5H2O) was dissolved in double distilled de-ionized water to prepare 0.5 M solution. Predetermined amount of Lithium hydroxide (LiOH) was dissolved in de-ionized water to prepare 1 M solution. Under rigorous magnetic stirring of the LiOH solution CuSO4 solution was added drop by drop for five minutes and the stirring was maintained for 2 hours at room temperature (30°C). After the reaction a white precipitate was observed at the bottom of the flask. This solution was then aged for 24 hours. The color of the precipitate solution was turned into grey. The precipitate was filtered and subsequently washed with distilled de-ionized water thrice for the removal of unreacted salts if any. The precipitate was then dried in an ordinary furnace at 150°C for further characterization. Results: X-ray diffraction data confirmed the formation of well crystalline CuO having monoclinic unit cell structure. The crystallite size was ~ 12 nm as calculated from the XRD pattern. Transmission electron microscope images revealed that the bipod-like structure is composed of several crystallites. The lengths of the bipods are ~ 300 nm with a waist size ~ 100 nm. The UV-visible spectroscopic data revealed a strong absorption at ~ 376 nm and the band gap was calculated to be 2.51 eV. FTIR spectrum revealed the existence of only Cu=O bonds. In the Raman shift data two strong peaks were found at 273 cm-1, and 608 cm-1 that owe to the Ag mode and Bg mode respectively. Room temperature photoluminescence spectroscopy revealed that the CuO nanoparticles exhibit broad strong emission at ~ 472 nm. After decomposing we observed three peaks at 436, 469 and 495 nm. The emission peak at 469 nm arises due to near band edge transition. The emission peak at 495 nm arises due to shallow level defect states related transitions. Conclusion: In conclusion, we have fabricated CuO nano-bipods using a simple wet chemical method. XRD pattern indicates the formation of well crystalline and pure CuO without any impurity. The nano-bipods exhibit sharp absorption peak at ~ 376 nm with optical band gap energy of 2.51 eV. FTIR spectrum and Raman shift data confirms the formation of CuO with the presence of Ag mode (273 cm-1) and Bg mode (608 cm-1). The fabricated CuO nano-bipods exhibit strong PL emission at 469 nm owing to the recombination of free excitons at the absorption band edge in the UV region associated with other low intense deep level emission. Few relevant patents to the topic have been reviewed and cited.

Background: Germanium (Ge) nanostructures exhibit wide range of potential applications in the field of nanoscale devices due to their excellent optical and electrical properties and have gained significant interest due to the Bohr exciton radius. Bohr radius of Ge (24.3 nm) is larger than that of Si (4.9 nm), leading to quantum size effects and nanostructures with controllable bandgaps. Methods: This article provides a comprehensive review on various electrolytes for electrodeposition procedures developed to obtain the Ge nanostructures of desired structure, diameter, and density. We discuss the growth mechanisms and influence of different parameters such as type of solution, concentration, and value of applied potential or current density. Results: The ionic liquids can be used for the development of Ge nanostructures and provide extensive electrochemical windows for electrodeposition. The obtained SixGe1-x structures also exhibited strong color change (from red to blue) at room temperature during the electrodeposition, which is likely to be due to a quantum size effect. Conclusion: The main advantages of the ionic liquids are ‘it does not decompose’, easy to purify and dry. Moreover, it exhibits fairly extensive electrochemical windows greater than 5 V for electrodeposition. Electrodeposition of SixGe1–x nanostructures from ionic liquids is quite a favorable process. The 3DOM Ge electrode is a promising material for nextgeneration lithium ion battery because of its high irreversible specific capacity. Few relevant patents to the topic have been reviewed and cited.

Background: Nanomanipulation techniques have gone through several phases to be used in scientific explorations not only to reveal more characteristics of nano, micro and mesoscopic phenomena but also to build functional nano-devices useful for specific applications. The nano-manipulator becomes a key instrument for technology bridging between sub-nano and mesoscale. The recent patents have exhibited integration of various functions in the nano-devices requiring sub-nanometer precision and highly stable manipulator with substantial pulling/pushing forces. This work reviews patents and works on conceptual designs of existing nanomanipulators with specific features. This includes design analysis leading to ultra-precision motion and stability with discussion of enabling technology. A novel integrated and numerically controlled instrument for nanomanipulation, visualization and inspection/characterization of materials at sub-nanoscale will be presented with a feature to keep the same datum for all operation and hence improve accuracy of samples. Methods: This paper has undertaken a review search in a structured examination of bibliographic databases for published and issued patents using a focused review keyword of nano-manipulation. The quality of selected patents was appraised using standard tools. The characteristics of screened patents were described, and a deductive qualitative content analysis methodology was applied to understand the modeling and testing of nanomachining process, the exact construction of nanostructure arrays and the inspection of devices with complex features. Results: The paper encompassed forty patents. Fourteen patents exhibited the manipulation at the micro scale (MEMS manipulations), others outlined systems with sub-micron resolution and workspace range in mesoscale. Standard scale manipulation were described in 13 patents assuming only systems comprising positioning stages, arms and end-effectors where positioners are a few centimeters in size with workspace higher than one cm3. Finally, ten patents included in this review described the importance of end-effectors being extremely important in nanomanipulation as they do support the function defining the manipulation e.g. grippers, sprayers, Nano-tweezers. Conclusion: The findings of this patents review confirm the relevance of the nanomanipulation of objects in 3D system coupled with real time imaging having higher resolution in comparison with the standard manipulators including AFM, TEM, STM, SEM or NSOM. In terms of tooling, AFM cantilever tips, etched tungsten tips or tips with electron beam deposition can be used to manufacture or develop nanodevices e.g. nanowires in in-situ SEM. In handling and manipulating in ambient conditions, commercial microfabricated grippers although available, are less used compared to CNT nanotweezers. Nanomanipulation is currently enabled for nanoscale samples by on-chip operations using promising MEMS and NEMS devices to relatively large samples by the meso and standard scale nanomanipulators. Manipulation is comprehensive and requires multiple functions enabled by various types of end-effectors and probes actuated with high precision. Piezo actuators are at the moment of great performance. Nano and sub-nano samples require proper environment e.g, with electron microscopy to monitor and manipulate including testing, inspecting and fabricating and assembling.

Background: Zirconium alloys have very useful properties for nuclear facilities applications having low absorption cross-section of thermal electrons, high ductility, hardness and corrosion resistance. However, there is also a significant disadvantage: it reacts with water steam and during this (oxidative) reaction it releases hydrogen gas, which partly diffuses into the alloy forming zirconium hydrides. A new strategy for surface protection of zirconium alloys against undesirable oxidation in nuclear reactors by polycrystalline diamond film has been patented- Czech patent 305059: Layer protecting the surface of zirconium alloys used in nuclear reactors and PCT patent: Layer for protecting surface of zirconium alloys (Patent Number: WO2015039636-A1). The zirconium alloy surface was covered by polycrystalline diamond layer grown in plasma enhanced chemical vapor deposition apparatus with linear antenna delivery system. Substantial progress in the description and understanding of the polycrystalline diamond/ zirconium alloys interface and material properties under standard and nuclear reactors conditions (irradiation, hot steam oxidation experiments and heating-quenching cycles) was made. In addition, process technology for the deposition of protective polycrystalline diamond films onto the surface of zirconium alloys was optimized. Results: Zircaloy2 nuclear fuel pins were covered by 300 nm thick protective polycrystalline diamond layer (PCD) using plasma enhanced chemical vapor deposition apparatus with linear antenna delivery system. The polycrystalline diamond layer protects the zirconium alloy surface against undesirable oxidation and consolidates its chemical stability while preserving its functionality. PCD covered Zircaloy2 and standard Zircaloy2 pins were for 30 min. oxidized in 1100°C hot steam. Under these conditions α phase of zirconium changes to β phase (more opened for oxygen/hydrogen diffusion). PCD anticorrosion protection of Zircaloy nuclear fuel assemblies can significantly prolong lifetime of Zirconium alloy in nuclear reactors even above Zirconium phase transition temperatures. Even after ion beam irradiation (10 dpa, 3 MeV Fe2+) the diamond film still shows satisfactory structural integrity with both sp3 and sp2 carbon phases. Zircaloy2 under the carbon-based protective layer after hot steam oxidation test differed from the original Zircaloy2 material composition only very slightly, proving that the diamond coating increases the material resistance to high temperature oxidation. Conclusions: Zirconium alloys nuclear fuel pins’ surfaces were covered by compact and homogeneous polycrystalline diamond layers consisting of sp3 and sp2 carbon phases with a high crystalline diamond content and low roughness. Diamond withstands very high temperatures, has excellent thermal conductivity and low chemical reactivity, it does not degrade over time and (important for the nuclear fuel cladding) being pure carbon, it has perfect neutron cross-section properties. Moreover, polycrystalline diamond layers consisting of crystalline (sp3) and amorphous (sp2) carbon phases could have suitable thermal expansion. Zirconium alloys coated with polycrystalline diamond film are protected against undesirable changes and processes. Further, the polycrystalline diamond layer prevents the reaction between the alloy surface and water vapor. During such reaction, water molecules dissociate and initiate formation of zirconium dioxide and hydrogen, accompanied by the release of large amount of heat. Thus the protective layer prevents the formation of hydrogen and the release of reaction heat. Few relevant patents to the topic have been reviewed and cited.

Background: Nanocomposites consisting of spatially confined polymeric chains are of great interest due to their application in optoelectronic and photonics devices. Polymer layered silicate nanocomposites have attracted much attention in industry as well as academia owing to their remarkable physical and chemical properties as compared to conventional polymer nanocomposites. Methods: In present study, comparative investigation of the in-situ polymerization of poly(ophenylenediamine) intercalated montmorillonite has been done via two methods i.e using poly(o-phenylenediamine) as filler for MMT in one case and as matrix in the other. Intercalation and in-situ polymerization was confirmed by FT-IR, UV-Visible spectroscopy and XRD studies. TEM and optical microscopy studies confirmed the self-assembled morphology of nanocomposites while the fluorescence properties revealed that controlled emission could be achieved by confining poly(o-phenylenediamine) in MMT galleries. Result: Intercalation and in-situ polymerization of o-phenylenediamine within MMT was successfully carried out using sonochemical technique. The growth of conducting polymers in the interlayer region of the clays has been shown to dramatically improve the properties of conducting polymers. Also, the loading of the polymer in the MMT has shown to influence the optical properties of the nanocomposite. IR spectra and XRD analysis confirmed the intercalation of POPD and its polymerization within the clay galleries. UV spectra revealed the doped state of POPD within clay galleries. Highest oscillator strength of 0.0137 was observed for POPD:MMT-1:0.25. Spherical self-assembled morphology was attained for POPD:MMT-1:0.25. XRD revealed major shift of 82.5 Å for the nanocomposite POPD:MMT-1:1, POPD:MMT-1:0.5 and MMT:POPD-1:0.25. Blue shift of 20 nm was noticed in the fluorescence spectra of POPD:MMT-1:0.25 and POPD:MMT-1:0.5 which was correlated to the intense interaction between NH of POPD with SiO of MMT. Highest quantum yield of 0.345 was achieved in case of POPD:MMT-1:0.25. The gallery confinement was found to control the optical as well as morphological characteristics of the nanocomposite. The controlled growth of POPD chains and their minimum aggregation resulted in the formation of self-assembled morphology. Thus, by choosing the optimum filler loading and by controlling its interaction with the matrix, nanocomposites with controlled architecture can be designed. Conclusion: It can be concluded that intercalation and exfoliation of nanocomposites largely depends on the experimental conditions such as type of conducting monomer, clay and organic modifier etc. The preparation technique and processing conditions influence the overall properties of the nanocomposites. Thus, by choosing the optimum filler loading and by controlling its interaction with the matrix, nanocomposites with controlled architecture can be designed. Few relevant patents to the topic have been reviewed and cited.

Background: It is well-known that multi-layer films with nanostructure can give novel properties by interfacial phenomenon and quantum confinement effects. Nanostructured multi-layer thin films are presently being analyzed for their vast applications in the area of optoelectronics technology particularly photovoltaics. Hereof, two dimensional thin films with nanostructure are of prime importance due to their structure dependent optical, electrical, and opto-electronic properties. It has been revealed that these films exhibit quantum confinement effects with band gap engineering. The main focus of the research is to evaluate the effect on structural and optical properties with number of layers. Methods: Nanostructured SnO2-Ge multi-layer thin films were fabricated using electron beam evaporation and resistive heating techniques. Alternate layers of SnO2 and Ge were deposited on glass substrate at a substrate temperature of 300 °C in order to obtain uniform and homogeneous deposition. The substrate temperature of 300 °C has been determined to be effective for the deposition of these multi-layer films from our previous studies. The films were characterized by investigating their structural and optical properties. The structural properties of the as-deposited films were characterized by Rutherford Backscattering Spectroscopy (RBS) and Raman spectroscopy and optical properties by Ultra-Violet-Near infrared (UV-VIS-NIR) spectroscopy. Results: RBS studies confirmed that the layer structure has been effectively formed. Raman spectroscopy results show that the peaks of both Ge and SnO2 shifts towards lower wavenumbers (in comparison with bulk Ge and SnO2, suggesting that the films consist of nanostructures and demonstrate quantum confinement effects. UV-VIS-NIR spectroscopy showed an increase in the band gap energy of Ge and SnO2 and shifting of transmittance curves toward higher wavelength by increasing the number of layers. The band gap lies in the range of 0.9 to 1.2 eV for Ge, while for SnO2, it lies between 1.7 to 2.1 eV. Conclusion: Analysis of results suggests that the nanostructured SnO2-Ge multi-layer thin film can work as heterojunction materials with quantum confinement effects. Accordingly, the present SnO2-Ge multi-layer films may be employed for photovoltaic applications. Few relevant patents to the topic have been reviewed and cited.