Formaldehyde (HCHO) is widely used in construction, wood processing, furniture, textile, and carpeting industries. However, it is highly toxic. It strongly irritates human eyes and nose, and is a carcinogen. In this paper, the effects of gas concentration and operating temperature on the sensing properties of the nano-SnO2 flat-type coplanar gas sensor arrays to formaldehyde were studied. The results revealed that the nano-SnO2 flat-type coplanar gas sensor arrays exhibited good sensitivity such as a fast response, short recovery time, and low detection limit. In addition, the adsorption and surface reactions of formaldehyde on SnO2 films were also studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) at 200–300 °C. Molecularly adsorbed formaldehyde, formate, dioxymethylene, polyoxymethylene, H2O, and CO2 surface species were formed during formaldehyde adsorption at 200–300 °C. Moreover, a possible mechanism of the reaction process was given.

We present a route for direct growth of boron nitride via a polyborazylene to h-BN conversion process. This two-step growth process ultimately leads to a >25x reduction in the root-mean-square surface roughness of h-BN films when compared to a high temperature growth on Al2O3(0001) and Si(111) substrates. Additionally, the stoichiometry is shown to be highly dependent on the initial polyborazylene deposition temperature. Importantly, chemical vapor deposition (CVD) graphene transferred to direct-grown boron nitride films on Al2O3 at 400 °C results in a >1.5x and >2.5x improvement in mobility compared to CVD graphene transferred to Al2O3 and SiO2 substrates, respectively, which is attributed to the combined reduction of remote charged impurity scattering and surface roughness scattering. Simulation of mobility versus carrier concentration confirms the importance of limiting the introduction of charged impurities in the h-BN film and highlights the importance of these results in producing optimized h-BN substrates for high performance graphene and TMD devices.

A Cu–Ni sectioned cathode made up of two hemicycles of each of the metals was used for reactive co-sputtering of a thin film combinatorial library of Cu–Ni oxides covering a total compositional spread of 63 at.%. The thickness profiling of the library showed a nonuniform film thickness with a maximum region shifted toward the Cu side of the cathode. The presence of CuO, Cu2O, NiO, and metallic Cu–Ni alloys was identified during the scanning x-ray diffraction investigations along the compositional spread. A distinct structural zone was defined between Cu–14 at.% Ni and Cu–19 at.% Ni, where the scanning electron microscopy investigations showed a higher surface porosity combined with smaller grain sizes. This zone corresponds to the maximum film thickness region and correlates well with the position of the maximum work function of the Cu–Ni oxide films as mapped using a scanning Kelvin probe. During local corrosion studies focused on Cu dissolution, an improved corrosion resistance was identified in the Ni rich side of the compositional spread.

This study presents results of selective laser melting (SLM), powder metallurgy (PM), and casting technologies applied for producing Ti–TiB composites from Ti–TiB2 powder. Diffraction patterns and microstructural investigations reveal that chemical reaction occurred between Ti and TiB2 during all the three processes, leading to the formation of Ti–TiB composites. The ultimate compressive strength of SLM-processed and cast samples are 1421 and 1434 MPa, respectively, whereas the ultimate compressive strengths of PM-processed 25%, 29%, and 36% porous samples are 510, 414, and 310 MPa, respectively. The Young's moduli of porous composite samples are 70, 45, and 23 GPa for 25%, 29%, and 36% porosity levels, respectively, and are lower than those of SLM-processed (145 GPa) and cast (142 GPa) samples. Fracture analysis of the SLM-processed and cast samples shows shear fracture and microcracks across the samples, whereas failure of porous samples occurs due to porosities and weak bonds among particles.

Dispersions containing 1 mg/mL of several carbon nanomaterials were used to deposit films containing 1 to 20 layers. The electrical properties of the composite films were characterized via impedance spectroscopy along two directions: in-plane on the film topmost surface and also through the thickness. It was found that carbon black nanoparticles never achieved full in-plane interconnection while the multiwalled carbon nanotube (MWNT) and single-walled carbon nanotube were already percolated at one layer. Graphite flakes showed a complete percolation curve that allowed its resistance to change by 6–7 orders of magnitude. The differences in the microstructure, electrical response, and thermal decomposition behavior of these carbon nanomaterial–paper substrate films were explained by detailed equivalent circuit analysis of the impedance spectra. Interpretation was supplemented by scanning electron microscopy images and thermal analysis via Differential Scanning Calorimetry/Thermogravimetric Analysis (DSC/TGA). Thru-plane electrical properties were for the most part similar, although only films with short MWNT showed a clearly infiltrated network structure.

In the present study, we report an activation and enhancement of room temperature ferromagnetism in pure ZnO and V-doped ZnO (Zn0.95V0.05O and Zn0.90V0.10O) thin films by trioctylphosphine (TOP) functionalization. X-ray diffraction patterns show a slight decrease in the intensity of the diffraction peak on TOP functionalization. Atomic force micrographs of pure and V-doped ZnO films reveal no disorder in the film surface on TOP functionalization. The chemical bond formation of TOP on ZnO film surface was examined by x-ray photoelectron spectroscopy measurements. Photoluminescence measurements of TOP-functionalized ZnO films show enhancements of UV emission and quenching of visible emission. TOP-functionalized ZnO films reveal enhanced ferromagnetic behavior as evidenced from vibrating sample magnetometer measurements.