Synthesis of Silver Sulfide Colloidal Solutions in Heavy Water D 2 O
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GANIC MATERIALS AND NANOMATERIALS
Synthesis of Silver Sulfide Colloidal Solutions in Heavy Water D2O S. I. Sadovnikov* Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, Yekaterinburg, 620990 Russia *e-mail: [email protected] Received April 24, 2020; revised May 15, 2020; accepted May 27, 2020
Abstract—It is for the first time that silver sulfide colloidal solutions were prepared by chemical deposition from silver nitrate and sodium sulfide solutions in heavy water D2O. Sodium citrate served as the stabilizer. The sizes of Ag2S nanoparticles in colloidal solutions were assessed by dynamic light scattering (DLS) measurements and electron microscopy. The silver sulfide nanoparticles in heavy water colloidal solutions prepared from batches having various reagent concentrations had sizes in the range from 3 to 19–20 nm. The increasing silver nitrate concentration and decreasing sodium citrate concentration in the batch only slightly increased the sizes of Ag2S nanoparticles in the prepared colloidal solutions. The silver sulfide colloidal solutions prepared with heavy water D2O retained their stability and unchanged nanoparticle sizes when stored for more than 100 days. Keywords: heavy water, chemical deposition, low-energy neutrons DOI: 10.1134/S0036023620100174
INTRODUCTION Advanced methods for studying nanosystems use various types of radiation to determine the structure of nanosized objects in the bulk and on surfaces. The specific properties of low-energy neutrons with a wavelength of ∼0.15 nm (1.5 Å), which include thermal and cold neutrons, make it possible to effectively use their scattering to study solids, liquids, and colloidal systems. Neutron diffraction methods, in particular small-angle neutron scattering [1–3], are sensitive to structural organization features at a level of 1–100 nm. Small-angle X-ray and neutron scattering is one of the most effective investigation tools for structures with sizes ranging from one to several hundred nanometers. The diffraction pattern of a sample is the result of the interference of radiation scattered elastically and coherently, i.e., without changing the wavelength and phase. Small-angle scattering can be used to study disordered items without special sample preparation. The basic correlations that relate the scattering intensity to the structure of the item are determined by the scattering power of inhomogeneities and the contrast of their electron density against the background matrix [1, 2, 4]. So, small-angle scattering makes it possible to study items of various physical natures and in various physical states, including nanoparticles in an amorphous matrix (glass) or colloidal particles (quantum dots) in solution [5, 6]. When studying colloidal solutions by small-angle neutron scattering, one should keep in mind that irradiating neutrons are absorbed by
hydrogen atoms and are almost not scattered. Therefore, it is almost impossible to obtain a diffraction pattern when ordinary water is used as a solvent. For this reason, h
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