| 초록 |
Oxynitride-type perovskites BaTaO2N and SrTaO2N possess high dielectric constants () But, the dielectric behavior of the Nb-perovskite oxynitrides has never been observed so far. We regard that the dielectric polarization in Nb compounds is hindered by the presence of reduced Nb species. To suppress the Nb reduction in the perovskite oxynitrides, two different approaches were employed in the preparation of BaNbO2N. First, the starting reactants were provided with Ba/Nb ＞ 1, to avoid the possibility of excess Nb. Second, part of Nb was replaced with lower-valent cations, to form BaNb1xMxO2+4xN14x (M = Li, Na). Diffuse-reflectance spectroscopy and X-ray photoelectron spectroscopy indicated that the introduction of M+ is effective in preserving the Nb5+ state. |
