Retention of a nanostructure in thermoelectric materials through rapid sintering (e.g., field-assisted sintering) is generally associated with leaving certain amounts of porosity due to short sintering times. In this study, the influence of porosity on the thermoelectric transport properties in Bi2Te3-based alloys was studied by changing the sintering pressure during spark plasma sintering. N-type Bi2Te3 and p-type (Bi0.2Sb0.8)2Te3 were sintered at 673 K using pressures from 50 to 300 MPa to obtain different levels of porosity. Electrical resistivity, thermal conductivity, Seebeck coefficient, carrier concentrations, and Hall mobility were measured and characterized. The results show that increasing sintering pressure is effective in reducing porosity, which lowers electrical resistivity and increases the carrier concentrations. The transport properties were fitted to general effective medium equations and demonstrate that in p-type (Bi0.2Sb0.8)2Te3 sintered at high pressures, decreases in electrical resistivity and lattice thermal conductivity exceeded the Seebeck coefficient reduction, improving the thermoelectric figure of merit.

Carbon nanotubes (CNTs) supported Pd nanoparticle (NP) catalysts (Pd/CNTs) were prepared by a green and facile synthesis method based on hydrogen-bonding self-assembly. The size and loading of Pd NPs on catalysts were easily controlled by tuning both the relative amount of citrate to Pd salt in the solution and the relative amount of Pd NPs to CNTs. The size of Pd NPs on as-prepared catalysts can be tuned in the range of 3–6 nm, and Pd loading can be controlled in the range of 0–19 wt%. The catalysts were characterized by Brunauer–Emmett–Teller measurement, x-ray diffraction spectroscopy, and x-ray photoelectron spectroscopy. The performance of Pd/CNTs catalysts was evaluated in the hydrogenation of nitrobenzene. Compared with the catalysts prepared by the impregnation method or supported on conventional supports, Pd/CNTs catalysts show relatively higher activity and selectivity. The recyclability tests indicate that the Pd/CNTs catalysts can be used at least five times without significant loss in activity and selectivity.

A new type of cross-linked poly(vinyl alcohol) (PVA)-sulfosuccinic acid (SSA) polymers were synthesized by varying the amount of SSA and then blending with 3-amino-1,2,4-triazole (ATri) and 1H-1,2,4-triazole (Tri) at different stoichiometric ratios to obtain proton conductive membranes in anhydrous state. The proton conductivities of membranes were investigated as a function of azole composition, SSA composition, and operating temperature. The final structures of the copolymers were confirmed by Fourier transform infrared spectra. The resultant hybrid membranes are transparent, flexible, and showed good thermal stability up to approximately 200 °C. Differential scanning calorimetry results illustrated the homogeneity of the materials. The cross-linking of the structure was confirmed by the alteration of solubility of the membranes. Methanol permeability measurements showed that the composite membranes have lower methanol permeability compared to Nafion 112. The proton conductivity of the membranes continuously increased with increasing SO3H content and 3-amino-1,2,4-triazole (ATri) content. A maximum proton conductivity of 7.26 × 10−3 S/cm was achieved for ATri-3 at 140 °C under anhydrous conditions. Incorporation of ATri unit (according to Tri unit) significantly increased the proton conductivity of the membranes, probably due to the ion transport channel or network structures formed in the membranes.

Eu3+, Bi3+ codoped Lu2O3 powders (Eu = 2.5 at.%, Bi = 0–3.0 at.%) were prepared using the sol–gel method. Fourier transform infrared spectroscopy, x-ray diffraction, and excitation and emission spectra were carried out to characterize the synthesis, structure, and luminescent properties. The excitation spectra show a strong peak at 350–390 nm, corresponding to the Bi3+1S0 → 3P1 transition, and the emission spectra present the emission from 5D0 → 7FJ (J = 0, 1, 2, 3, 4) level of Eu3+. The intensity of the reddish emission at 612 nm was monitored as a function of the Bi3+ content and showed a light yield increment of ≈400% compared to a monodoped sample at 1.0% at. Bi3+, produced by an energy transfer process from Bi3+ to Eu3+. This was a consequence of the overlapping of the Bi3+3P1 → 1S0 emission with the f–f Eu3+ transitions.

The relationship between electric current direction and recrystallization rate as well as the resulting texture induced by electric current pulses (ECPs) was investigated in a Cu–Zn alloy. To distinguish the effect of electric current direction on recrystallization rate, the same input energy was exerted upon the samples to eliminate the effect of Joule heating induced by ECPs. Results showed that the recrystallization-related nucleation rate could be greatly enhanced when the electric current was dispositioned at an angle to the rolling direction. The main mechanism for the different nucleation rates might be ascribed to the different driving forces for recrystallization induced by ECPs when there was an angle between the electric current direction and the rolling direction.By all reckoning, it was expected that the ECP treatment would provide a promising approach for controlling the nucleation rate by changing the exerted electric current direction.

Nano-cellular foams were successfully produced from blends of styrenic and acrylic polymers by a two-step batch foaming process using carbon dioxide as the blowing agent. Addition of poly(ethyl methacrylate) or poly(methyl methacrylate-co-ethyl acrylate) to styrene-acrylonitrile copolymers, even at a low level, resulted in very homogeneous foams with smaller cell size and narrower cell size distribution than with the individual polymers. The best nanofoams produced from miscible blends have average cell sizes below 100 nm, cell densities up to 5 × 1015 cm−3 and medium-to-low relative densities (void fraction between 60 and 70%). Contrary to previous studies, it was found that blends with lower CO2 solubility gave higher cell density nanofoams. This suggests new mechanisms for the nucleation of foams from these blends at the nanoscale.

We investigate the orientation transition and strain relaxation in oxygenated epitaxial strontium-doped lanthanum nickelate, La1.875Sr0.125NiO4+δ (LSNO) thin films grown on single crystal strontium titanate, SrTiO3 (STO) substrates. Structural evolution has been studied as a function of film thickness by x-ray diffraction, pole figure analysis, and transmission electron microscopy (TEM). The LSNO layer grows epitaxial (OR1) with respect to the STO substrate with an orientation (001)OR1//(001)STO and <001>OR1//<001>STO. This orientation is maintained up to approximately 15 nm as observed from TEM, at which point it undergoes reorientation and lattice mismatch strain relaxation. The growth continues with a new orientation (OR2) as (100)OR2//(001)OR1 and with <100>OR2//<001>OR1 and <001>OR2//<001>OR1 with respect to the epitaxial LSNO layer. We consider possible mechanisms in detail leading to these phenomena given that the potassium nickel fluoride (K2NiF4)-structured lattice is able to accommodate excess oxygen interstitials and corresponding changes in the Ni valence state. By investigating the phase space of deposition parameters, we experimentally identify key factors leading to the reorientation phenomena.