Adsorption Properties of Novel Materials Based on the InP–ZnS System

Abstract—

Adsorption properties of solid solutions and binary components of the InP–ZnS system with respect to NO₂ and NH₃ in the temperature intervals of 250–490 K and initial pressures of 15–30 Pa have been studied for the first time. In selecting adsorbates, their unequal electron nature and toxicity is taken into account. An analysis of experimental dependences of adsorption α_p = f(T), α_T = f(P), and α_T = f(t) and calculated values of differential heat, differential entropy, activation energy of adsorption, and electrical conductivity “behavior” under condition of adsorption is conducted. As a result, the temperature conditions for occurrence of physical and chemical activated adsorption are established. With regard to the results of IR spectroscopy, the studies of acid-base properties of the surfaces of the system components, and their charging under conditions of adsorption, the ideas are substantiated about the nature of active centers, the role of which is taken by surface coordinately unsaturated atoms (primarily In and Zn atoms) and about the donor-acceptor mechanism of gas adsorption with gases participating as acceptors. Increased activity of the surfaces of the system semiconductors with respect to basic gases, which is confirmed unambiguously by the direct adsorption studies, and also the change in electrical conductivity under conditions of adsorption even at room temperature have been the basis for recommending the studied semiconductors to be used for fabricating the corresponding low-temperature sensors.