Study of size effects in structural transformations of bcc Zr films by molecular-dynamics simulation

Study of peculiarities of the thermal expansion of zirconium thin films by molecular-dynamics simulation

“…as the boundary of the structural reorientation transition is approached) a slight decrease in the a x and a y parameters is observed, though the parameter c continues growing. As seen from the phase diagram Temperature-Thickness [9], the bct (0 0 1) film of thickness N z ¼ 20 u:c. is stable in the temperature range from 600 K to 1500 K, and at temperatures above 1500 K it undergoes an orientational transformation into bct (1 1 0). The decrease in the a x ; a y lattice parameters of the bct (0 0 1) film in the range 1200-1500 K may be associated with stresses that arise in these directions resulting in a structural transformation.…”

“…Returning to the phase diagram Temperature-Thickness [9], we can assume that the critical size of 17 u.c (6.1 nm) is due to the fact that with an increase of the film thickness the proportion of surface atoms decreases and so does the contribution from the surface vibration modes. As a result the film with (0 0 1) surface becomes energetically more favorable, whereas calculations of the bcc lattice energy at T ¼ 0 K showed the (1 1 0) film to be energetically favorable for all the film thicknesses (see Fig.…”

“…The studies performed in [9,10] have shown that the temperature of the bcc ! hcp structural transition in zirconium films essentially depends on the thickness.…”

“…Earlier [9], we constructed a phase diagram TemperatureThickness for zirconium films. This diagram presents the regions of final structures stable for no less than 1 ns, one time step being equal to 1 fs.…”

Решеточная Теплоемкость Наноструктурированных Материалов На Основе Титана/Циркония И Алюминия

“…Для сравнения в эту же таблицу добавлены результаты первопринципных расчетов, сделанных различными методами, и экспе-риментальные данные для пленок титана, циркония и алюминия с ГЦК-структурой. Заметим, что результаты расчетов равновесных параметров решетки и упругих модулей для нанопленок существенно зависят от тол-щины пленки, как это было показано нами ранее на примере пленок циркония [12]. В этом случае вычис-ления были проведены с потенциалом, предложенным в работе [13], обозначенным в таблице EAM3.…”