In this study, a novel gas sensor is proposed based on a three-dimensional reduced graphene oxide/polyaniline (3D RGO/PANI) hybrid, which is synthesized by a hydrothermal method for detecting NH3 gas at room temperature. The 3D RGO/PANI hybrid is characterized by field emission-scanning electron microscopy, Fourier transform infrared and x-ray diffraction. The specific surface area is analyzed using the Brunauer–Emmett–Teller (BET) equation. The as-synthesized sensing materials with an appropriate amount of polyaniline nanowires (PANI-NWs) can effectively prevent aggregation of the neighboring graphene sheets and directly act as adsorption sites for NH3 molecules. In comparison with its pure 3D RGO counterpart, the 3D RGO/PANI (1:1) hybrid exhibits 44.7 times enhanced response to 100 ppm NH3, suggesting the remarkable effect of PANI-NWs in improving the sensitivity. This work gives new insights into boosting the sensitivity and selectivity of detecting NH3 gas by incorporating PANI-NWs into 3D RGO.

Ti:Cu 3 N thin films were deposited on Si(111), quartz, and glass slide substrates by DC magnetron sputtering in molecular nitrogen ambient. The structural properties of Ti:Cu 3 N thin films were studied by X-ray diffraction (XRD) analysis. XRD measurements show diffraction band with peaks close to the (100) and (200) diffraction lines of cubic antiReO 3 structure of Cu 3 N. The Ti:Cu 3 N nano-crystalline size is in the range 22-27 nm. Lattice constant expansion reflects Ti incorporation causing the excess nitrogen to occur. Surface morphology shows that the N richness suppresses the grain growth. The optical absorption spectra indicate a remarkable shift to higher energies of the absorption edge due to higher N concentration and quantum size effect. Photoluminescence (PL) measurement shows interstitial N excess and Ti impurity produce shallow and deep levels, respectively. Thermal stability of the Ti:Cu 3 N films annealed at 300 and 400°C is improved in comparison with that of Ti free Cu 3 N films.

We present electrical resistivity ͑͒ measurements for the intercalation compound Fe x TiSe 2 ͑0 ഛ x Ͻ 0.16͒ over the temperature range from 4.2 to 300 K, and angle-resolved photoemission spectra for x = 0, 0.05, and 0.14 at 50 and 250 K ͑or 280 K͒. At 250 K, TiSe 2 is a semimetal having hole pockets centered at the ⌫ point and electron pockets around the L points of the Brillouin zone. Upon intercalation, Fe-derived flat bands appear just below the Fermi energy, and the Se 4p derived bands forming hole pockets at the ⌫ point are lowered. At 50 K, band folding due to 2a ϫ 2a ϫ 2c superlattice is observed clearly near the L point for the host and x = 0.05, while it vanishes for x = 0.14, consistent with the -T data. The critical concentration for the suppression of the superstructure ͑0.05Ͻ x c ഛ 0.075͒ can be explained reasonably well by the percolation threshold of a two-dimensional-trianglar lattice consisting of seven Ti atoms, which is estimated to 1 / 14 ͑=0.0714͒.

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A sintered Ti13Cu87 target was sputtered by reactive direct current (DC) magnetron sputtering with a gas mixture of argon/nitrogen for different sputtering powers. Titanium-coppernitrogen thin films were deposited on Si (111), glass slide and potassium bromide (KBr) substrates. Phase analysis and structural properties of titanium-copper-nitrogen thin films were studied by X-ray diffraction (XRD). The chemical bonding was characterized by Fourier transform infrared (FTIR) spectroscopy. The results from XRD show that the observed phases are nano-crystallite cubic anti rhenium oxide (anti ReO3) structures of titanium doped Cu3N (Ti:Cu3N) and nanocrystallite face centered cubic (fcc) structures of copper. Scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX) were used to determine the film morphology and atomic titanium/copper ratio, respectively. The films possess continuous and agglomerated structure with an atomic titanium/copper ratio (∼ 0.07) below that of the original target (∼ 0.15). The transmittance spectra of the composite films were measured in the range of 360 nm to 1100 nm. Film thickness, refractive index and extinction coefficient were extracted from the measured transmittance using a reverse engineering method. In the visible range, the higher absorption coefficient of the films prepared at lower sputtering power indicates more nitrification in comparison to those prepared at higher sputtering power. This is consistent with the formation of larger Ti:Cu3N crystallites at lower sputtering power. The deposition rate vs. sputtering power shows an abrupt transition from metallic mode to poisoned mode. A complicated behavior of the films' resistivity upon sputtering power is shown.