Search

A mixed amines thiogermanate (NH 4) 2 [NH 2 (CH 3) 2 2 Ge 2 S 6 was reported. Its structure features isolated [Ge 2 S 6 4− anions which are separated by NH 4 + and [NH 2 (CH 3) 2 +. UV–Vis diffuse reflectance spectroscopy coupled with Tauc's analysis indicates an indirect optical transition semiconductor with an energy gap value of 3.50 eV. Furthermore the energy transition type was supported by first-principles electronic structure calculation. A mixed amines thiogermanate, namely (NH 4) 2 [NH 2 (CH 3) 2 2 Ge 2 S 6 has been successfully synthesized by solvothermal reaction. Single crystal X-ray diffraction indicates the compound crystallizes in monoclinic space group P 2 1 / c with the lattice parameters: a = 6.9647(14) Å, b = 15.719(3) Å, c = 7.2042(14) Å, β = 92.76(3)°. The structure features a zero-dimensional [Ge 2 S 6 4− anions which are separated by NH 4 + and [NH 2 (CH 3) 2 +. Hydrogen bond interactions play a crucial role in its structure formation. X-ray powder diffraction and TG-DSC measurements were performed to study its phase purity and thermal stability. UV–Vis diffuse reflectance spectroscopy coupled with Urbach fitting indicates an indirect optical transition semiconductor with a bandgap value of 3.50 eV. The result of first-principles electronic structure calculation supported the experimental indirect optical transition but the value was under estimated as 3.061 eV. Density of states and population analysis were also calculated to reveal the origin of the bandgap and bond interaction for its structure formation. [ABSTRACT FROM AUTHOR]

A novel lanthanide germanate, namely RbNdGe 2 O 6 , has been successfully synthesized by high-temperature solid-state reaction in open air atmosphere for the first time. Single crystal X-ray diffraction indicates a 3D framework composed of 1D neodymium oxygen chains connected with cyclogermanate Ge 3 O 9 units with Rb+ located in the internal space. X-ray powder diffraction coupled with Rietveld refinement reveals the sample's phase purity we have prepared. Thermal behavior analysis shows RbNdGe 2 O 6 is very stable, it doesn't decomposition until heated up to 998 ​°C. UV–visible absorption and diffuse reflection spectrum feature characteristic absorption bands of f -electron transition and an optical bandgap value of 4.65 ​eV. Magnetic susceptibilities measurement gives significant antiferromagnetic interactions between magnetic centers. The photodegradation experiments were performed to evaluate photocatalytic activities of RbNdGe 2 O 6. By using P25 as a reference, RbNdGe 2 O 6 features to be an effective visible-light-driven catalyst in photodegrading methylene blue. Although the BET value of RbNdGe 2 O 6 is only 3% that of P25, the photocatalytic activity reaches 0.55 times that of P25. Furthermore, the proposed photocatalytic mechanism which dominated by holes was further verified by adding ammonium oxalate as a quencher. New compound RbNdGe 2 O 6 was reported for the first time. Its structure features a 3D framework composed of 1D neodymium oxygen chains connected with cyclogermanate Ge 3 O 9 units with Rb+ located in the internal space. This material features an impressive visible-light-driven photodegradation methylene blue, and the proposed photocatalytic mechanism was also studied. Image 1 [ABSTRACT FROM AUTHOR]