Surfactant-thermal Syntheses, Structures, And Optical Properties Of Novel Ouaternarv Thioantimonates (Ⅲ)

Chalcogenides are a new type of inorganic material with diverse crystal structures, which have wide application prospect such as ion exchange, nonlinear optics and photocatalysis. The synthesis and characterization of chalcogenides have attracted considerable interests in solid-state chemistry. Recently, thioantimonates(III) have attracted increasing interests. Thioantimonates(Ⅲ) typically contain the diverse Sb(Ⅲ)Sx (x= 3,4,5) coordination modes owing to the stereochemically active 5s2 lone pair electrons associated with Sb(III). Furthermore, these asymmetric Sb(Ⅲ)Sx primary building units could undergo a series of condensation into complex polyanions under basic conditions, which contributes to complex crystal structures and specific physico-chemical properties. Surfactants stand out as the reaction medium, not only for the high thermal stability and negligible vapor pressure, but also with low price and multifunctional properties, seem to be the ideal solvent. They have been widely used in the synthesis of nanocrystals, however, using surfactants as reaction media to grow novel quaternary chalcogenides(Ⅲ) remains less explored.In this dissertation, we employed the neutral surfactant PEG-400 as reaction reaction media, successfully developed variety of quaternary thioantimonates(Ⅲ) with novel crystal structures. The route is common with productivity and the crystals are all in good quality.1. Three quaternary ACu2SbS3 (A= K, Rb, Cs) thioantimonates(Ⅲ) crystallize in a triclinic unit cell with the space group, P-1 (No.2), which belongs to a layered structure type. All three compounds are dark red block-shaped, which are reasonably stable in air and water for three months at room temperature. KCu2SbS3, RbCu2SbS3, and CsCu2SbS3 are approximately stable up to 280℃,330℃ and 380℃without apparent weight loss, respectively. The optical band gaps are around 1.53 eV for KCu2SbS3,1.67 eV for RbCu2SbS3 and 1.63 eV for CsCu2SbS3, respectively, which fall in the range of narrow gap semiconductors and are consistent with the colors of these compounds. The calculated band gap of KCu2SbS3 isl.13 eV, and it’s a direct-band semiconductor material.2. Two quaternary ACuSb2S4 (A= Rb, Cs) thioantimonates(Ⅲ) crystallize in a monoclinic unit cell with the space group, C2/c (No.15), which belongs to a porous three-dimensional framework. All the compounds are dark red block-shaped, which are reasonably stable in air and water for three months at room temperature. ACuSb2S4 (A= Rb, Cs) are approximately stable up to 500℃ without apparent weight loss. The optical band gaps are around 1.70 eV, which fall in the range of narrow gap semiconductors and are consistent with the colors of the compounds. The calculated band gap of RbCuSb2S4 is 1.27 eV, and it’s not a direct-band semiconductor material.3. Three quaternary A2Ag3Sb3S7 (A= K, Rb, Cs) thioantimonates(Ⅲ) crystallize in a orthorhombic unit cell with the space group, Cmc21 (No.36), which belongs to a layered structure type. All three compounds are yellow needle-shaped, which are reasonably stable in air and water for three months at room temperature. Rb2Ag3Sb3S7 and Cs2Ag3Sb3S7 are approximately stable up to 500℃without apparent weight loss, respectively. The optical band gaps are around 2.11 eV for Rb2Ag3Sb3S7and 2.13 eV for Cs2Ag3Sb3S7, respectively, which fall in the range of narrow gap semiconductors and are consistent with the colors of these compounds.