The phase transition temperature of vanadium dioxide (VO₂) thin films shifts to the vicinity of room temperature by reducing the dimensions from microscale to nanoscale without the use of any dopant. This quantum size effect elucidated by studying the structural, optical and electrical properties of nanothin and microthin films of VO₂ across their semiconductor–metal phase transitions has been demonstrated in this reported work. The films fabricated on glass substrates via the inorganic sol–gel route were characterised by Rutherford backscattering spectrometry (RBS), X-ray diffractometery, scanning electron microscopy, ultraviolet–visible spectroscopy and the four-probe method. The RBS results estimate a layer thickness of 15 and 291 nm for nanothin and microthin films, respectively. The films were polycrystalline in their nature of [011] orientation with regular and irregular crystallites of a cuboidal surface morphology. Estimation of crystallite size revealed that nanothin films attain poor crystallinity as compared with microthin films. The blue shift was observed in nanothin films from microthin films as maximum absorption occurred at wavelengths of 360 and 443 nm, respectively. Optical bandgaps of 2.3 and 1.87 eV were found for nanothin and microthin films, respectively. Depletion in metal-to-semiconductor and semiconductor-to-metal transition temperatures were experienced from higher temperature regimes of 341 and 335 K for microthin films to lower temperature regimes of 319 and 305 K for nanothin films, respectively.

Numerical analysis of a bilayer graphene nanoribbon (BLGNR) using the reproducing kernel particle method (RKPM) – a true meshless approach – is reported. Electrostatic analysis of the BLGNR is performed using the RKPM approach. Validation of the structure is executed by comparing the result with an equivalent single conductor model and shows better accordance. Radio frequency (RF) analysis of the BLGNR as the interconnect is studied using advanced design systems with the quasi-static analysis derived through the RKPM method. The simulation results in a return loss of −89.69 dB and transmission loss of −0.00028 dB at 1 THz which is suitable for RF interconnect applications.

This Letter presents an analytical formulation for predicting the radial breathing mode (RBM) frequency of boron nitride nanotubes (BNNTs) with arbitrary chirality. Accurate material properties of the BNNTs are usually not available and the values of the material properties have certain amount of scatter, and some level of uncertainty. In the present investigation, the convex modelling is utilised to consider the bounded uncertain material properties in calculating the RBM frequency of the BNNTs. The results are compared with available data in the literature. Present study may provide useful information on the RBM frequency of the BNNTs with arbitrary chirality in practical applications.

Quantum dot gate field-effect transistor (QDGFET) generates three states in their transfer characteristics. A successful model can explain the generation of third state in the transfer characteristics of the QDGFET. The innovative circuit design using QDGFET can be used to design different ternary logic. This Letter discusses the design of ternary logic static random access memory using QDGFET.

NiO catalyst supported on Fe-pillared montmorillonite (5–15 wt% Ni) was prepared via a simple conventional impregnation method. The physicochemical properties of the Ni catalyst were characterised by X-ray diffraction, inductively coupled plasma-atomic emission spectrometry and transmission electron microscopy. The Ni catalyst, together with organic montmorillonite (OMMT), was employed to prepare multi-walled carbon nanotubes (MWCNTs) by using polypropylene (PP) as a precursor. An increase in Ni loading of the catalyst led to a significant increase in the yield of MWCNTs at the expense of a slight decline in quality of the obtained MWCNTs. Moreover, OMMT altered the degradation process of PP, which resulted in a much higher fraction of light hydrocarbons in degradation products. As such, a substantial increase in the yield of MWCNTs was attained. In addition, the obtained MWCNTs were used as flame retardant for PP, and significantly enhanced thermal stability and flame retardancy according to thermogravimetry analysis and cone data, respectively. PP/MWCNTs nanocomposite exhibited higher degradation temperature, longer ignition time, much lower heat release rate and smoke production rate. This work offers an efficient Ni catalyst to convert PP into MWCNTs which could be applied as flame retardant for polymers.

A microwave-assisted heating method for growing well-aligned zinc oxide (ZnO) nanorods on the ZnO/silicon (Si) substrate is developed. For ZnO nanorods growth, a thin ZnO seed layer was deposited on an Si substrate by sputtering technique. The ZnO nanorods grown on the ZnO/Si substrate were synthesised in aqueous solution mixed with zinc nitrate hexahydrate and hexamethylenetetramine (HMTA) under microwave heating. The scanning electron microscopy (SEM) images and X-ray diffraction results exhibit that the ZnO nanorods with hexagonal phase, single crystalline, and highly oriented along (002) plane are obtained successfully. SEM images also show that the morphology and diameter of the synthesised ZnO nanorods can be controlled by adjusting the molar ratio of Zn(NO₃)₂·6H₂O to HMTA. The Raman scattering results evidence the vertical well-aligned ZnO nanrods with larger diameter are strain-free. The investigations of the photoluminescence spectra suggest that the ultraviolet emission peak of the synthesised ZnO nanorods depending on its controllable diameter would be applicable for various nanodevice fabrications.

An efficient and versatile method for fabricating nanopatterns by a lift-off procedure is presented. The method involves an inked technique based on the poly(dimethylsiloxane) (PDMS) mould to fabricate a nanopatterned UV-curable resist as the top-layer and poly(methyl methacrylate) (PMMA) as the underlayer. The minimal residues are left on the PMMA because PDMS absorbs the organic molecules of UV-curable resist after the transferred step. High O₂ reactive ion etching selectivity of the top-layer to the underlayer is necessary to create the undercut pattern profile that is essential for the stable lift-off process. The UV-curable resist shows high etch resistance to O₂ plasma and PMMA serves as an underlying resin to create an undercut profile which is essential for the lift-off process. The etch rates of the PMMA film and UV-curable resist by O₂ plasma were examined as a function of bias voltage under various oxygen conditions during the etching process. To reveal the mechanism of etch resistance, the chemical composition of UV-curable resist was analysed before and after the O₂ plasma etching process by using X-ray photoelectron spectroscopy. As a result, the periodical patterns were fabricated using this bilayer lift-off process, which shows great potential in the fabrication of micro/nanodevices and in their applications.

Microelectromechanical systems (MEMS) utilise time-variant capacitors as transducers in many applications. However, this kind of component can introduce harmonics and disturbances into the circuit with an AC power source, which is difficult to evaluate through closed-form solutions. This Letter proposes an iterative solution to analyse the dynamics of MEMS devices which contain a time-variant capacitor and an AC source. First, the expressions of the time-variant capacitor, AC source and their derivatives with respect to time are determined. Then, an initial solution that is sufficiently close to the actual solution is determined using linear circuit analysis. On the basis of the previous steps and the principles of the iterative method, an approximated solution combining the initial solution and its iteratively-derived higher-order terms is reached. Adding additional higher-order terms can improve the accuracy of the solution. A case study considering a MEMS device which has an AC power source and sinusoidal motion was performed using MATLAB Simulink. The simulation study further demonstrated that: (i) this iterative solution can effectively analyse the dynamics of MEMS devices with a time-variant capacitor and an AC power source; and (ii) computing additional higher-order terms derived from the initial solution can further improve the solution's accuracy.

Longitudinal vibration of nanorods embedded in an elastic medium with elastic restraints at both ends is studied based on the non-local elasticity theory. Using Fourier sine series and Stokes’ transformation, a coefficient matrix is obtained. It is very useful for calculating the vibrational frequencies of a nanorod with any type of boundary condition (rigid or restrained). Finally, carrying out some numerical computations, the effects of the elastic medium, non-local parameters and elastic restraints at both ends on the values of vibrational frequencies have been determined. The numerical results are validated through comparison of calculated values with those in the literature.

A facile synthesis method of poly(3,5-dimethoxyaniline) (P(3,5-DMA)) hollow microspheres was demonstrated by the interfacial polymerisation of 3,5-dimethoxyaniline (3,5-DMA) using camphorsulfonic acid (CSA) as the doping agent and soft template. The obtained P(3,5-DMA) hollow microspheres possess narrow size distribution and uniform shape. A possible growth mechanism of the hollow microspheres was proposed through studying the change in morphologies of P(3,5-DMA) at different reaction times. It is believed that the slow diffusion speed of monomer from the oil phase to the water phase in the interfacial polymerisation system controls the progress of polymerisation. Moreover, the interaction between amino group of the monomer and the sulfonic acid group of the doping agent micelle guides the formation of the hollow microspheres.

Epitaxial graphene films have been prepared by pulsed laser deposition. X-ray photoelectron spectroscopy analysis shows that the carbon binding energy is 284.7 eV, corresponding to sp²-C. Raman spectroscopy indicates that there exists 2D and D peaks and thus graphene structures have been formed. Meanwhile, according to high-resolution transmission electron microscopy analysis, suitable depositing temperature for graphene films is found to be 873 K and the single oriented crystal domains of graphene are observed only with the condition of 100 pulses laser.

A novel and inexpensive way to deposit nanostructured cadmium oxide (CdO) coatings is described. Metallic Cd is evaporated by heating a silicon carbide crucible, via microwave radiation at standard atmosphere conditions. The Cd vapour rises from the crucible and reacts with the atmospheric oxygen depositing on a glass substrate. CdO coating is homogeneously distributed above the glass surface and it presents a well-defined cubic-shaped nanostructure. The as-deposited CdO coatings showed good hydrophobic properties and achieved symmetric contact angles of 112°. The hydrophobic behaviour was lost after a 75 min of heat treatment at 723 K.

Cobalt (Co)-doped colloidal silica abrasives were synthesised by seed-induced growth method. Time-of-flight secondary ion mass spectroscopy was used to characterise the composition of the obtained abrasives. The morphology of the abrasives was measured by using scanning electron microscopy. The chemical mechanical polishing (CMP) performances of the Co-doped colloidal silica abrasives on sapphire substrates were investigated. Experiment results indicate that the Co-doped colloidal silica abrasives exhibit lower surface roughness and higher material removal rate (MRR) than that of pure colloidal silica abrasive under the same testing conditions. Furthermore, the inductively coupled plasma-atomic emission spectrometry and X-ray photoelectron spectroscopy were also used to investigate the acting mechanism of the Co-doped colloidal silica in sapphire CMP. Analysis results show that cobalt aluminate appears after polishing, implying the tribochemistry reaction occurs during CMP. The chemical reaction between element cobalt and sapphire surface during CMP can promote the chemical effect in CMP and lead to the increasing of MRR.

An initial urea-assisted combustion and subsequent high-temperature crystallisation route have been used to prepare porous Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ microspheres. The as obtained microspheres with the size of 2–4 μm are composed of numerous nanoparticles, and these nanoparticles with clear corner and edge have the size of 100–200 nm. A possible formation process of porous microspheres structures is discussed. As lithium-ion battery cathodes, the porous microspheres can deliver an initial discharge capacity of 252.3 mAh g⁻¹ with high Coulombic efficiency of 80.6% at current density of 20 mA g⁻¹, and keep a stable discharge capacity of 115.5 mAh g⁻¹ at 1000 mA g⁻¹. Although the sample obtained without urea only deliver a discharge capacity of 66.7 mAh g⁻¹ at 1000 mA g⁻¹. Maybe, the facile urea-assisted combustion route is suitable for the synthesis of lithium-rich layered oxides as lithium-ion battery cathodes.

A series of MnO₂/carbon nanotubes (CNTs) catalysts were prepared to use for the selective catalytic reduction (SCR) of NO with NH₃ via liquid-phase redox method at ambient temperature. The resulting samples possessed an amorphous MnO₂ and, a higher SCR activity than that obtained by wet impregnation technique.