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キーワード:
Oxides, X-ray diffraction, Neutron diffraction, Transmission electron microscopy (TEM), Catalytic properties
要旨:
The Ca1−3xBi2xФxMoO4 system (0.025 ≤ x ≤ 0.30, where Ф represents cation vacancies) was synthesized and studied. The 0.025 = x ≤ 0.15 compositions show a tetragonal defect scheelite structure. Powder X-ray and neutron diffraction patterns for compositions with 0.15 < x ≤ 0.225 exhibit a tetragonal supercell with asup ≈ √5a, csup ≈ c where a and c are the tetragonal scheelite cell parameters. Transmission electron microscopy shows that Ca0.4Bi0.4MoO4, crystals consist of three crystallographic domains: (1) defect scheelite; (2) tetragonal superlattice and (3) incommensurately modulated. Photocatalytic properties were studied using Rhodamine B water solutions under UV light. Catalytic activity increases with increasing Bi content. The conductivity of 0.15 < x ≤ 0.225 compositions is 10−7 to 10−8 S cm−1 in the range 500–650 °C, while compositions in the range 0.025 = x ≤ 0.15 show conductivity values from 10−3 to 10−8 S cm−1 from 500 to 800 °C.
