Polyaniline(PANI)/Ce(NO_3)_3 composite with short fiber-like shape was synthesized successfully in a poly(2-arcylamido-2-methylpropane sulfonic acid) aqueous solution. A comparison of SEM images found that short fiber-like composites can be obtained by controlling the dosage of Ce(NO_3)_3. The length and diameter of short fiber-like PANI/Ce(NO_3)_3 composite was about 630 and 200 nm, respectively. A special conjugated structure had formed via Ce^(3+) ions and –NH– group in the quinonoid ring of PANI, which was characterized by means of Fourier transform infrared(FTIR) spectroscopy, Ultraviolet-visible(UV-Vis) spectroscopy and X-ray photoelectron spectroscopy(XPS). Short fiber-like PANI/Ce(NO_3)_3 composite exhibited a high conductivity, a large capacitance and an enhanced anticorrosion property. Linear four-probe method confirmed that the electrical conductivity of composites was improved with the presence of Ce^(3+) ions. The corrosion potential of PANI/Ce(NO_3)_3 composite increased to-79 mV at 10 wt% of Ce(NO_3)_3. Meanwhile, the minimum density of corrosion current(1.4 μA/cm^2) was also achieved.
The electron transport of linear atomic chain trodes was investigated by using the density Green＇s function method. We have calculated of MgB2 sandwiched between Au（100） elecfunctional theory with the non-equilibrium the corresponding cohesion energy and conductance of junctions in different distance. It is found that, at the equilibrium position, the Au-B bond-length is 1.90 A, the B-Mg bond-length is 2.22 A, and the equilibrium conductance is 0.51G0 （Go=2e^2/h）. The transport channel is almost formed by the π antibonding orbitals, which was made up of the Px and Py orbital electrons of B and Mg atoms. In the voltage range of -1.5 to 1.5 V, the junctions show the metallic behaviors. When the voltage is larger than 1.5 V, the current decreases gradually and then negative differential resistance appears almost symmetrically on both positive and negative bias.
We performed a first-principles study of the electronic, elastic, and thermal properties of the rareearth hexaboride CeB6 using the local density approximation （LDA） in consideration of the effective onsite Coulomb parameter Ueff. To systemically evaluate the effect of Ueff on the structure of the material, the dependences of the lattice parameter a0 and bulk modulus B on Ueff were examined in the framework of the LDA＋U and GGA（PBE）＋U scheme. We obtained a lattice constant a0, elastic constants Cij, and a bulk modulus B at 0 K and 0 GPa that were in good agreement with the experimental results and other theoretical findings. We focused on the electronic structure by analyzing the variation of the density of states with different Ueff values and pressures, which indicates the metallic characteristic of CeB6. Interestingly, the effect of high pressure was similar to that of increasing Ueff, as the peaks at the bottom of the conduction band moved to the high-energy region in both cases. The elastic constants Cij, bulk modulus B, shear modulus G, Young＇s modulus E, shear-sound velocity Vs, and longitudinal-sound velocity VL were calculated from 0 to 120 GPa. Additionally, the Debye temperature D and elastic Debye temperature E were systematically calculated using the thermodynamic methods in the range of 0-100 GPa. This research may provide a comprehensive understanding of the Kondo compound CeB6 and similar rare-earth hexaborides.
