Production Of Nanoparticles Of AgAsSe2 and Ag3AsSe3 Compounds

Abstract

    Ternary compounds (nano- and microparticles) of AgAsSe₂ and Ag₃AsSe₃ have been synthesized from approximately equimolar mixtures of silver nitrate, sodium metaarsenite and sodium selenosulfate with prepared by refluxing selen powder with concentrated sodium sulfite solution under hydrothermal conditions in ethylene glycol medium. The solutions were put into a 100 mL Teflon-lined stainless steel autoclave Speedwave four BERGHOF and sealed and then heated at the temperature of 443 K during 8 hours (pH = 5-4). The products were filtered via the glass filter and washed by deionized water and absolute ethanol for several times, then dried at 353 K in vacuum oven for at least 1 hour for analysis. The thermogravimetric (TG) and electron microprobe analysis have been carried out. The results showed that the composition of silver selenoarsenates compounds corresponding to the formule AgAsSe₂ and Ag₃AsSe₃. The results of SEM image and shows the typical morphologies of synthesized products in which tubular and stick shaped like nano-particles can be observed and their size can be estimated from 140 nm to 310 nm. The compound of AgAsSe₂ and Ag₃AsSe₃ was constructed using X-ray phase and differential-thermal analyses. It is ascertained by X-ray powder diffraction (XRD) that the parameters of AgAsSe₂ crystallized in the tetragonal space group R3^-m with a = 12.54 Å, c = 11.14 Å, α = 90⁰, β = 90⁰,γ = 90⁰, Z = 5, Ag₃AsSe₃ (this compound is an allotrope of β-Ag₃AsSe₃) crystallizes in the orthorhombic space group Pnma, a = 8.11 Å, b = 11.34 Å, c = 20.73 Å, α = 90⁰, β = 90⁰,γ = 90⁰, Z = 8. The results of differential thermal analysis (DTA) AgAsSe₂ compound is melting congruently at T_g = 683 K, Ag₃AsSe₃ with incongruent type of melting at T_g = 663 K was established. 

Keywords

• hydrothermal synthesis,organic solvent,arsenic (III) selenide,XRD,scanning electron microscopy

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