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Hydrothermal Synthesis and Crystal Structure of a Novel Bismuth Oxide: (K_0.2Sr_0.8)(Na_0.01Ca_0.25Bi_0.74)O₃.

ABSTRACT: A novel distorted perovskite-type (K_0.2Sr_0.8)(Na_0.01Ca_0.25Bi_0.74)O₃ was prepared by a hydrothermal method using the starting materials NaBiO₃·nH₂O, Sr(OH)₂·8H₂O, Ca(OH)₂, and KOH. Single-crystal X-ray diffraction of the novel compound revealed a GdFeO₃-related structure belonging to the monoclinic system of the space group Cc with the following cell parameters: a = 11.8927 (17) Å, b = 11.8962 (15) Å, c = 8.4002 (10) Å, and β = 90.116 (9)°. The final R-factors were obtained as R ₁ = 0.0354 and wR ₂ = 0.0880 (using all the data). K⁺ and Sr²⁺ ions were distributed at four types of A-sites. On the other hand, four Bi⁵⁺-sites (Bi1, Bi2, Bi3, and Bi4) were occupied by four Ca²⁺ ions (Ca1, Ca2, Ca3, and Ca4), and the first three B-sites were occupied predominantly by Bi⁵⁺ with Na⁺ ions. The forth B-site was occupied predominantly by the Ca²⁺ ion with Bi⁵⁺ ions. Two types of B-sites, thus forming tilted distorted (Na/Ca/Bi)O₆ and (Bi/Ca)O₆ octahedra, have an ordering of 3:1 represented as (K/Sr)₄(Na/Ca/Bi)₃(Bi/Ca)O₁₂. The distorted (Na/Ca/Bi)O₆ and (Ca/Bi)O₆ octahedra formed a perovskite-type network by corner sharing with features closely matching those of a GdFeO₃-type structure. The novel compound is the first example of a perovskite-type bismuth oxide containing only Bi⁵⁺ in a system without a Ba atom and has a unique ordering (3:1) of the B site. The compound showed photocatalytic activity for phenol degradation under visible light irradiation.

SUBMITTER: Hossain KM

PROVIDER: S-EPMC8223429 | biostudies-literature |

REPOSITORIES: biostudies-literature

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