Low Temperature Solvothermal Syntheses,Crystal Structures,and Physical Properties Of New Multinarv Chalcogenides Containing 15 Group Elements(As,Sb)

Multinary chalcogenides belong to semiconductors with excellent physical and chemical properties which contribute to their rich components and structures.They are promising candidates in modern science field such as nonlinear optics,photocatalyst,ion exchanges and photoelectrochemical cells.Therefore,the research on synthesis of multinary chalcogenides has become a very important branch in inorganic synthetic chemistry.Comparing with high temperature synthetic strategy used to synthesize chalcogenides,more metastable phases with rich structures are more likely to form under lower temperature.As a comparatively more effective synthetic method,low temperature solvothermal method has been successfully applied to synthesize new multinary chalcogenides.A variety of factors affect the reaction of solvothermal method such as raw materials,reaction media,reaction times and temperatures,which bring even more advantages for us to explore diverse new chalcogenides.Therefore,the proper raw materials,reaction media and reaction conditions are the keys to prepare multinary chalcogenides with new structures and abundant properties.In this dissertation,we select 15 group element As,Sb and thiophile transition metal Ag,Cu as components,introduced these two kinds of ions into chalcogenide anions.Using alkaline meatal ions as equilibrium cations and hydrazine as the main reaction media,we synthesized a series of quaternary and pentanary chalcogenides via adjusting raw materials,solvents,temperatures and times of the reactions.Meanwhile,the synthetic conditions,crystal structures,thermal stability,band structures and photoelectrochemical properties were investigated.1.We use hydrazine hydrate as solvent,15 group metal Sb and transition metal Cu/Ag as components in chalcogenide anions,alkaline metal Ba2+ as the equilibrium cation.Adjusting reactant ratio,4 new quaternary thioantimonates:2D-BaAgSbS3(1)layer structure,3D-BaAgSbS3·H2O(2)framework structure,isomorphic 3D-BaCuSbS3(3)and BaCuSbSe3(4)framework structure were obtained.2.We use hydrazine hydrate as solvent,15 group metal As and transition metal Cu/Ag as components in chalcogenide anions,alkaline metal Ba2+ or Sr2+ as the equilibrium cation.Adjusting reactant ratio,3 new quaternary thioarsenates:2D-SrAg4As2S6·2H2O(5)layer structure,isomorphic 1D-BaAgAsS3(6)and BaCuAsS3(7)column structure were obtained.3.Based on hydrazine hydrate solvent,polyethylene glycol(PEG-400)and 1,2-propanediamineused were introduced into the reaction system.3 new 1D chain structure pentanary thioantimonates K2Ba3Cu2Sb2S10(8),Rb2Ba3Cu2Sb2S10(9)and Cs2Ba3Cu2Sb2S10(10)were synthesized successfully in the mixed solvent system.In the crystal structure,15 group metal Sb and transition metal Cu served as components into chalcogenide anions.Meanwhile,both alkaline metal and alkaline earth metal ions are the equilibrium cations.All the above compounds were characterized by single crystal X-ray diffraction,and the pure phases were prepared and physical properties were studied.Thermal stability analysis indicated that their crystal structures are stable at a certain temperature.UV-vis spectrum was used to determine their band gaps,and their band structures and density of states are investigated.Photoelectrochemical properties of BaCuSbS3(3),BaCuSbSe3(4),SrAg4As2S6·2H2O(5),BaAgAsS3(6),K2Ba3Cu2Sb2S10(8),Rb2Ba3Cu2Sb2S10(9)and Cs2Ba3Cu2Sb2S10(10)were characterized under visible light and the photocurrent responses were found.