Flux synthesis, crystal structure and electronic properties of the layered rare earth metal boride silicide Er3Si5–x B. An example of a boron/silicon-ordered structure derived from the AlB2 structure type

The ternary rare earth metal boride silicide Er3Si5–x B (x = 1.17) was synthesized from the elements using the tin flux method. It crystallizes in a new structure type in the space group R32 (a = 6.5568(1) Å, c = 24.5541(1) Å, Z = 6). The structural arrangement can be derived from the AlB2 structure type with boron/silicon ordering in the layered metalloid substructure made of [Si5B] hexagons. The presence or absence of the boron atoms involved in this ordered structure is discussed on the basis of difference Fourier syntheses and structural analysis, in relation with the binary parent structures AlB2 and Yb3Si5 (Th3Pd5 type). The electronic and bonding properties of Er3Si5–x B were analyzed and discussed via density functional theory (DFT) calculations and a crystal orbital Hamiltonian population (COHP) bonding analysis.

Molten-Salt Flux Mediated Synthesis of ZnO-SnO2 Composites: Effects of Surface Areas and Crystallinities on Photocatalytic Activity

In this study, ZnO-SnO2 composites were synthesized using flux synthesis, a synthetic approach different from previous studies, in which molten ZnCl2 acted both as a reactant and as the flux for the reaction. Their photocatalytic properties were measured for the degradation of the organic dye, methylene blue. It was found that as the temperatures of the synthesis increase, the specific surface areas of the ZnO-SnO2 composites decrease, which would decrease their photocatalytic activities due to decreased adsorption of the dye on the surface of the composites; while their crystallinity increases, which would increase their photocatalytic activities due to the smaller concentration of defects and thus improved mobility of the charge carriers. An interplay of those two factors affects their photocatalytic activities, with the composite with the highest photocatalytic activity degrading approximately 95% of the methylene blue dye within 10 minutes. By changing the temperature of the flux synthesis alone, the crystallinity and surface area of the ZnO-SnO2 composite can be changed, which provides a possible way to obtain ZnO-SnO2 composites with relatively high crystallinity and surface area to maximize their photocatalytic activity.

Molten-Salt Flux Mediated Synthesis of ZnO-SnO2 Composites: Effects of Surface Areas and Crystallinities on Photocatalytic Activity

In this study, ZnO-SnO2 composites were synthesized using flux synthesis, a synthetic approach different from previous studies, in which molten ZnCl2 acted both as a reactant and as the flux for the reaction. Their photocatalytic properties were measured for the degradation of the organic dye, methylene blue. It was found that as the temperatures of the synthesis increase, the specific surface areas of the ZnO-SnO2 composites decrease, which would decrease their photocatalytic activities due to decreased adsorption of the dye on the surface of the composites; while their crystallinity increases, which would increase their photocatalytic activities due to the smaller concentration of defects and thus improved mobility of the charge carriers. An interplay of those two factors affects their photocatalytic activities, with the composite with the highest photocatalytic activity degrading approximately 95% of the methylene blue dye within 10 minutes. By changing the temperature of the flux synthesis alone, the crystallinity and surface area of the ZnO-SnO2 composite can be changed, which provides a possible way to obtain ZnO-SnO2 composites with relatively high crystallinity and surface area to maximize their photocatalytic activity.