New crystal structure: synthesis and characterization of hexagonal wurtzite MnO.

Most transition metal oxides have a cubic rocksalt crystal structure, but ZnO and CoO are the only stable transition metal oxides known to possess a hexagonal structure. Unprecedented hexagonal wurtzite MnO has been prepared by thermal decomposition of Mn(acac)(2) on a carbon template. Structural characterization has been carried out by TEM, SAED, and a Rietveld analysis using XRD. The experimental and theoretical magnetic results indicate magnetic ordering of the hexagonal wurtzite MnO. Density functional calculations have been performed in order to understand the electronic and piezoelectric properties of the newly synthesized hexagonal wurtzite MnO.

Spectral reflectivity recovery from the tristimulus values using a hybrid method.

This study proposes an effective and accurate mechanism for spectral reflectivity recovery based on a hybrid technique. Adaptive non-negative matrix transformation, three-dimensional interpolation, and two-dimensional interpolation were reconstructed to an integrative hybrid recovery method. The existing spectral reflectivity data of 1269 Munsell matte color chips were used as reference data. Under the standard condition of a D65 illuminant and a 10° observer of 1964 CIE, the spectral reflectivity of the 1269 Munsell colors was reconstructed successfully using the optimized hybrid recovery method. The root mean square error and goodness of fitting were used to determine the quality of the presented method. Using the hybrid method, the strategy for fast and reliable spectral reflectivity recovery of given images were also presented and demonstrated.

Investigation of THz birefringence measurement and calculation in Al2O3 and LiNbO3.

Based on the polarization-sensitive terahertz time-domain spectroscopy, we measured the birefringence for Al2O3 and LiNbO3 single crystals, which correspond to trigonal structures that have an uniaxial birefringence, in the THz frequency range of 0.25 to 1.4 THz. For more comprehensive understanding of the THz birefringence, the measured birefringence is compared with the results of ab initio calculations. The measured birefringence shows good agreement with the calculated value.

Evidence of the Bi(3+) lone-pair effect on the charge-ordering state: resistivity and thermoelectric power of Bi(0.5-y)La(y)Sr(0.5)MnO(3) (0.0≤y≤0.4).

Polycrystalline samples of Bi(0.5-y)La(y)Sr(0.5)MnO(3) (0.0≤y≤0.4) (BLSMO) have been synthesized to investigate the Bi(3+) lone-pair effect on the long-range charge-ordering (CO) state. Since the ionic size of La(3+) is similar to that of Bi(3+) and the Mn valence state does not change with La doping, we obtained the Bi lone-pair effect on the CO state without disturbance by other effects. The resistivity ρ(T) and thermoelectric power S(T) of BLSMO have been measured. A hysteretic behaviour was observed in both ρ(T) and S(T) for y = 0.1 and 0.2. From the onset of the hysteretic behaviour, we defined a charge-ordering temperature (T(CO)) and compared it to that of Bi(1-x)Sr(x)MnO(3) (BSMO). Finally, we found that the Bi(3+) lone pairs play an important role in the anomalously high T(CO) in BSMO.

A new parameter to control heat transport in nanofluids: surface charge state of the particle in suspension.

Although various conjectures have been proposed to explain the abnormal increase in thermal conductivity of nanofluids, the detailed mechanism has not been fully understood and explained. The main reason is due to the lack of knowledge of the most fundamental factor governing the mechanisms such as Brownian motion, liquid layering, phonon transport, surface chemical effects, and agglomeration. Applying a surface complexation model for the measurement data of hydrodynamic size, zeta potential, and thermal conductivity, we have shown that surface charge states are mainly responsible for the increase in the present condition and may be the factor incorporating all the mechanisms as well.