Formation of Indium Nanoparticles by Thermal Evaporation
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MATERIALS AND CERAMICS
Formation of Indium Nanoparticles by Thermal Evaporation G. N. Kozhemyakina,*, S. A. Kiikob, and O. E. Brylc a Shubnikov
Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics,” Russian Academy of Sciences, Moscow, 119333 Russia b Vladimir Dal Lugansk National University, Lugansk, 91034 Ukraine c Institute for Advanced Technologies and Piezotechniques, Southern Federal University, Rostov-on-Don, 344006 Russia *e-mail: [email protected] Received March 22, 2018; revised March 22, 2018; accepted March 26, 2018
Abstract—Indium nanoparticles were obtained by vacuum evaporation technique of indium onto a glass carbon substrate in high purity Ar atmosphere. A technique is proposed for determining the nanoparticle dimensions and shape using a specially developed program. It is found that at a molten indium evaporation time from 10 to 30 s, indium nanoparticles with dimensions of 10–100 nm and crystallites with dimensions up to 500 nm are formed on the substrate. The largest number (up to 37%) of indium nanoparticles with dimensions of 50–100 nm is obtained at an evaporation time of 10 s; up to 52% of these particles have a shape different from spherical. The average diameter of indium particles increased from 140 to 190 nm with an increase in the evaporation time. DOI: 10.1134/S1063774519030167
INTRODUCTION Metallic indium is crystallized in a face-centered tetragonal structure with lattice parameters а = 3.2512 Å and с = 4.9467 Å [1]. However, when the dimensions of In nanoparticles become less than 7 nm, their crystal structure is transformed from tetragonal into facecentered cubic with parameters а = 4.598 Å and с = 4.947 Å [2–4]. In addition, experimental studies indicate that the crystal structure inside of In nanoparticles differs from that on their surface and that the nanoparticle lattice is extended along the a axis and compressed along the c axis in comparison with bulk indium [4]. These transformations suggest appearance of novel properties in nanostructures, which are characterized by a higher percentage of the surface atoms with breaking bonds than the bulk crystals. The results of studying the properties of nanoscale indium were reported in ref. [5–9]. High-purity indium is applied in electronics as a dopant for the growth of semiconductor single crystals with different compositions and as the component of semiconductor compounds: InSb, InAs, and InP. Indium oxide is used as a material of transparent film electrodes in LC screens, low-melting solders, etc. In addition, indium transforms to the superconducting state at temperatures below 3.4 K [10]. These properties of indium suppose new nanoscale effects in its nanocrystalline state. Therefore, determination of the formation conditions for indium nanoparticles and development of the methods for determining their
dimensions are important for scientific study and application. The purpose of the present work was to study the conditions for formation of nanoscale indium by vacuum evaporation
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