A thermal decomposition route with different sintering temperatures was employed to prepare non-stoichiometric nickel oxide (Ni1−δO) from Ni(NO3)2·6H2O as a precursor.

This is the first report on the critical nature of nanolattice formability of different particle size (~4-10nm) of monodispersed nickel nanoparticles. They exhibit strikingly hexagonal close-packed (hcp) nanolattices without extra forces, whenever trioctylphosphine is (one of) the surfactant(s) . This clearly establishes the unique role of nanolattice formability of trioctylphosphine. The c/a ratios are interestingly identical to those of atomic lattices. An attempt has also been made to explain them based on the balanced attractive and repulsive forces of the surfactant-generated cation-anion pairs on the surface of the nanoparticles. The present findings therefore will provide a far-reaching vista to fabrication of varieties of natural nanolattices and their understanding on applications in a new paradigm. Notes and references

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We report the results of the Y substitution in Sr 1−x Y x Si 2 with x Յ 0.15 via measuring the temperature-dependent electrical resistivity, thermal conductivity, as well as Seebeck coefficient. Upon substituting Y onto the Sr sites, the electrical resistivity exhibit semiconducting behavior and the room-temperature electrical resistivity tends to reduce for x Յ 0.08. The thermal conductivity also decreases with increasing the Y content. Moreover, the Seebeck coefficient has a substantial increase and a maximum of about 220 V / K at around 80 K has been found for x = 0.08. These promising effects lead to a significant enhancement in the thermoelectric performance characterized by the figure-of-merit, ZT. A room-temperature ZT value of approximately 0.4 is thus achieved for Sr 0.92 Y 0.08 Si 2 , about one order of magnitude larger than that of stoichiometric SrSi 2 .

We have performed Seebeck coefficient ͑S͒ measurement for a series of high-quality Na x CoO 2 single crystals for 0.23Յ x Յ 0.84 from 10 to 300 K. The room-temperature S values were found to be around 30-100 V / K and increase with increasing Na content. The temperature dependence of Seebeck coefficient of this system was found to be very sensitive for x =1/ 2, which is most likely due to the significant modifications of band structure as a result of the magnetic and charge orderings below 88 and 51 K. The overall observed features of the S͑T͒ were analyzed in the framework of a narrow-band model. The physical parameters obtained from the fitting provide a satisfactory description of the composition and temperature dependences of Seebeck coefficient in the Na x CoO 2 system.