abstract |
In Formula (1), IA is a peak intensity of the maximum peak attributed to the Nb2TiO7 phase and appearing at 2θ of 26.0±0.1° in a wide angle X-ray diffraction pattern under CuKα rays as an X-ray source. IB is a peak intensity of the maximum peak attributed to the at least one Nb-rich phase and appearing at 2θ of 24.9±0.2° in the diffraction pattern. |