Synthesis and Structural Properties of Hybrid Powder Materials Based on Colloidal Silica and Silver Iodide
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hesis and Structural Properties of Hybrid Powder Materials Based on Colloidal Silica and Silver Iodide A. S. Averkinaa, *, T. E. Oshchepkovaa, V. A. Valtsifera, and V. N. Strelnikova aInstitute
of Technical Chemistry, Ural Branch, Russian Academy of Sciences—Perm Federal Research Center (branch), Ural Branch, Russian Academy of Sciences, ul. Akademika Koroleva 3, Perm, 614013 Russia *e-mail: [email protected] Received September 19, 2019; revised January 17, 2020; accepted January 23, 2020
Abstract—This paper considers approaches to the preparation of potential reagents for precipitation enhancement processes. New reagents have the form of hybrid powder materials produced via physical attachment of silver iodide crystals to colloidal silica particles. In our work, hybrid powder is thought of as a combination of an inert matrix (colloidal silica) and a modifier (silver iodide as an active reagent). We demonstrate that the way in which composite powders are synthesized influences the phase state of the modifier. We have studied structural characteristics of the synthesized powder materials. The results demonstrate that increasing the percentage of silica in the composition of the powders leads to predominant formation of the hexagonal crystalline phase of silver iodide. Keywords: powder materials, hybrid, structural properties, silica, silver iodide DOI: 10.1134/S0020168520070018
INTRODUCTION The best known means of weather control are cloud seeding, hail suppression, and fog dissipation. Conventional reagents for cloud seeding are liquid nitrogen, dry ice, silver iodide, alkali metal chlorides, and alkaline-earth metal chlorides, which are produced commercially [1, 2]. These reagents act on atmospheric moisture molecules only through crystallization or adsorption [2–5]. Despite the considerable number of pilot projects concerned with cloud seeding and fog dissipation (Espacenet patent search database, section A01G 15/00), this approach has found no wide application. This is due to the unstable effectiveness of the reagents (poor rheological performance parameters and narrow working temperature range because only one condensation mechanism is involved) [4] and the high price of the work (large consumption of expensive reagents per unit volume of the air layer) [5]. One way of resolving the problem is to produce hybrid powder materials (HPMs) based on an inert matrix and a modifier. The first such powders were developed by researchers at the Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine [6]. In their work, the method of levilites involves the application of a monomolecular layer of ice-forming reagents over the entire surface of a matrix, which serves only as a substrate, without participating in moisture condensation. The purpose of this work is to develop methods for the synthesis of HPMs in which both a modifier and
an inert matrix are jointly responsible for condensation mechanisms, improving the effectiveness of the reagent. The effect will be ensured by producing
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