Open AccessСтруктурный переход и температурные зависимости коэффициентов теплового расширения NaNO-=SUB=-3-=/SUB=-, внедренного в нанопористое стекло
Author(s) -
А. А. Набережнов,
О. А. Алексеева,
А.В. Кудрявцева,
Д.Ю. Чернышов,
Т.Ю. Вергентьев,
А. В. Фокин
Publication year - 2022
Publication title -
fizika tverdogo tela
Language(s) - English
Resource type - Journals
eISSN - 1726-7498
pISSN - 0367-3294
DOI - 10.21883/ftt.2022.03.52098.239
Subject(s) - materials science , thermal expansion , borosilicate glass , superstructure , diffraction , atmospheric temperature range , sodium nitrate , nanoporous , critical exponent , analytical chemistry (journal) , nanoparticle , phase transition , thermodynamics , composite material , chemistry , nanotechnology , optics , physics , chromatography , metallurgy
The temperature evolution of the crystal structure of a nanocomposite material obtained by introducing sodium nitrate NaNO3 from a melt under pressure into a nanoporous alkali borosilicate glass with an average pore diameter of 7 nm has been studied by the method of diffraction of synchrotron radiation in a wide temperature range upon heating. Analysis of the experimental diffraction patterns revealed a significant decrease in the temperature of the structural (orientational) transition by more than 50 K (up to 496 K) compared to bulk sodium nitrate. From the temperature dependence of the intensity of the superstructure peak (113), the dependence of the critical exponent β (T) for this transition was obtained and a significant difference from the critical exponent for a bulk material was found in the temperature range from 455 K to the transition temperature. Analysis of the broadening of Bragg reflections made it possible to estimate the average size (~ 40 nm) of sodium nitrate nanoparticles into the pores. An increase in the linear coefficient of thermal expansion in the [001] direction was found in NaNO3 nanoparticles in comparison with bulk material at temperatures above 450 K.