Thermo-physical Behavior of Nanomaterials with the Change in Size and Shape

Abstract

Thermo elastic properties of nanomaterials has been very interesting among the researchers during the last decade, still it is a great challenge to predict the exact thermoelastic behaviour of nanomaterials. In the present work we have studied the volume thermal expansion coefficient of low dimensional solid and the variation of Young's modulus with change in temperature for different shapes of nanomaterials by considering the effect of packing factor. We have computed the volume thermal expansion coefficient of Silver (Ag), Aluminum (Al), Copper (Cu), and Lead (Pb) with their varying size. The effect of temperature on Young's modulus of Silver (Ag), Gold (Au), Nickel (Ni), Copper (Cu) and Silicon (Si) has also been studied. The computed results are compared with available experimental data which confirms that the volume thermal expansion coefficient increases with reduction in size of the nanomaterials. It has been also observed that the Young's modulus has linear decrement with increase in temperature which indicates that Young's modulus of nanomaterials has negative temperature coefficient.

Study of the FCC-Au properties in a wide range of temperatures and pressures

“…To calculate the crystal properties using formulas (4)− (12), gold (Au, m(Au) = 196.967 a.m.u.) was taken, whose melting point at P = 0 is T m (P = 0) = 1337.58 K. Gold has a face centered cubic (FCC) structure (k n = 12, k p = 0.7405) and does not experience polymorphic phase transitions.…”

“…Note that expressions (4)− (12) do not take into account either vacancies or self-diffusion of atoms, because, as was shown in [24], their influence becomes negligible when the crystal is compressed. Here, as well as in [19][20][21][22][23][24], the contribution of the electronic subsystem to the thermodynamic parameters is not taken into account, because the potential (3) describes the pair interaction of electrically neutral atoms.…”

“…Thus, despite its simplicity, approximation (2) has received wide recognition and is used to calculate properties not only for crystalline substances, but also for amorphous, liquid and nanostructured substances [6][7][8][9][10][11][12]. The approximation (2) is sometimes also called as αB rule [8].…”

Изучение свойств ГЦК-Au в широком диапазоне температур и давлений

“…2, b показано изменение функции B T для ГЦК-Au при изотермическом изменении давления, а на рис. 2, c -при изотермическом изменении нормированного объема: (12). При использовании значения r 0 из (13) получим: V 0 = v 0 N A = 10.0663 cm 3 /mol, где N A = 6.0221367 • 10 23 mol −1 -число Авогадро (Avogadro constant).…”

“…Таким образом, несмотря на свою простоту, приближение (2) получило широкое признание и используется при расчете свойств не только для кристаллических веществ, но также для аморфных, жидких и наноструктурированных веществ [6][7][8][9][10][11][12]. Приближение (2) иногда также называют (αB rule) [8].…”