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Lead-free piezoelectric Mn-doped Na 0:5 K 0:5 NbO 3 (NKN) single crystals have been fabricated by self flux method using KF-NaF eutectic composition. The color of the obtained crystals was different depending on the doped Mn-chemicals. The large-sized single crystals with crystal face of orthorhombic (110) were obtained by optimized heat-treatment condition of the holding time at 1050 and 950 C of 5 h and the cooling rate of 0.25 C/min, and their piezoelectric properties were successfully measured by a resonance-antiresonance method. The piezoelectric strain constant (d 33 ) of 0.5 mol % Mn-doped NKN single crystal was 161 pC/N, and the longitudinal electro-mechanical coupling factor (k 33 ) showed 0.64. #

Vibrational analysis is carried out for the organic (cationic) part of a pentamethine streptocyanine dye, [(CH3)2N(CH)5N(CH3)2]+ClO4 - (alias SC5), by measuring its infrared and Raman spectra in solution and in the polycrystalline state and by calculating the vibrational force field and the IR and Raman intensities by the ab initio molecular orbital and density functional methods. It is found that a reasonable set of structural parameters and vibrational force field can be obtained for the SC5 organic part at the BHandHLYP/6-31G* level. The observed features of the IR and Raman spectra, including relative intensities, are well reproduced by the calculations at this theoretical level. Two strong IR bands observed in the 1600−1200-cm-1 region arise from the delocalized b1 modes along the bond-alternation coordinate of the conjugated chain. The strong IR intensities are explained by large charge fluxes induced by these modes due to the strong electron−vibration interaction. These modes also appear in the Raman spectrum in solution because of the interaction with the perchlorate ion existing at an asymmetric position near the conjugated chain. A delocalized a1 mode of the conjugated chain gives rise to a strong Raman band. Examination of the IR and Raman intensities and the vibrational force constants clearly shows that the conjugated chain of the SC5 organic part is a strongly correlated system. A detailed analysis of the origin of the IR and Raman intensities shows that the potential energy distribution is not necessarily a good indicator of the origin of intensities.

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