The temperature-induced anomalous liquid-structure change in melt ${\mathrm{In}}_{20}{\mathrm{Sn}}_{80}$ observed by Zu et al. [Phys. Rev. Lett. 89, 125505 (2002)] has been studied. The structure transition in ${\mathrm{In}}_{20}{\mathrm{Sn}}_{80}$ is further confirmed by the presence of an exothermic peak in the differential-scanning-calorimetry (DSC) curve. From experimental data of pair distribution functions, we calculated the viscosity $\left(\eta \right)$ and the excess entropy $\left(S\right)$ and found that there is a valley of viscosity in the $\eta \text{−}T$ curve and a valley of excess entropy in the $S\text{−}T$ curve, which are consistent with the internal-friction $\left(Q^{-1}\right)$ peak in the $Q^{-1}\text{−}T$ curve and the exothermic peak in the DSC curve, respectively. We decomposed $S$ into two parts, $S\left(1\right)$ and $S\left(2\right)$, which are related to the total potential and the isothermal compressibility, respectively. The behaviors of $S\left(1\right)$ and $S\left(2\right)$ tell us that the atomic bonds vary twice and the microstructures transform twice in the temperature range from 300  to 900 °C for liquid ${\mathrm{In}}_{20}{\mathrm{Sn}}_{80}$. The similar analysises of liquid ${\mathrm{In}}_{80}{\mathrm{Sn}}_{20}$ and liquid Sn reveal that Sn plays a crucial role in the discontinuous structure change in liquid ${\mathrm{In}}_{20}{\mathrm{Sn}}_{80}$.

• Received 13 September 2004

DOI:https://doi.org/10.1103/PhysRevB.71.064204