Формування інтерференційних функцій в області середнього порядку аморфних речовин

Abstract

Досліджено закономірності формування інтерференційних функцій (ІФ) аморфних речовин в області середнього порядку. Встановлено, що визначальний вплив на формування ІФ задають зовнішні координаційні сфери кластера. Порівняння отриманих результатів з експериментальними даними показує, що за відносною інтенсивністю реально на ІФ в області середнього порядку може проявлятися лише перша, найбільш інтенсивна осциляція.

On a model cluster with tetrahedral structure the common regularities of shaping of interferential function (IF) of amorphous substances are explored in the medium-range order region. It is offered to use the IF of the plurality of all atom pairs of two given chemical devices with fixed inter-atomic distance and equal probability orientations in any direction of space as the elementary part of the electron diffraction pattern of the amorphous substances. Is established that the singularities of IF shaping in the region of wave vectors answering medium-range order, differ cardinal from regularities of IF formation in the region of wave vectors answering the short-range order of amorphous substances. Defining influence on IF shaping makes the exterior coordination sphere (CS) of a cluster. With the “growth” of the cluster size all oscillations remain legible, and their amplitude in 3,5-4 times is less than amplitudes of oscillations of IF separate exterior CS. Position of si peaks of IF of clusters with an exactitude 2-3 % submit to the law siR = bi, where R – radius by last exterior CS of a cluster, and bi – a series of constants (b1 = 8,98; b2 = 15,36; b3 = 21,6; b4 = 28,0; … ). The intensities of the first two peaks of IF are varied considerably by a casual way with cluster growth up to first 15th CS. After that the changes of the intensities would became smaller and beginning approximately from 15th CS their values becomes stable. The comparison of the received results with experimental data shows, that proceeds from relative intensity on the IF in the medium- range order region the first most intensive oscillation can be displayed only.