## 3 Results
### Liquid Structure  
#### 3.1.1 Partial Radial Distribution Function  
(a) The LiCl concentration dependence  
Partial radial distribution function (PDF) is calculated in histogram form by binning pairwise distances into 200 bins from 0.0 to the maximum force cutoff (defined as \(\mathrm{r_{c}}=\mathrm{L/2}\)). The bins are of uniform size in a radial distance. Thus, a single bin encompasses a thin shell of distances in 3d and a thin ring of distances in 2d. PDFs of A-2, A-4, A-6, and A-8 at 1100 K are shown in Figure 2 to illustrate the influence of the LiCl concentration on the structure of ternary systems. The quantitatively structural information containing the first peak position, \(\mathrm{r_{max}}\), the first peak height, \(\mathrm{h_{max}}\), the first valley position, \(\mathrm{r_{min}}\), and running integral coordination number, N(\(\mathrm{r_{min}}\)) are summarized in Table 3, which were determined by fitting PDFs (R\({}^{2}=1.0\)). The running integral coordination number was obtained by a spherical integration of g(r) from 0 to \(\mathrm{r_{min}}\). The structural parameters of the ternary systems were in good agreement with results of a similar composition [22]. For cation-anion pairs, though the variations of the first peak positions of potassium are a little greater than lithium sodium ions across the concentration, the changes (maximum change was 0.05 A) were subtle. However, the first peak heights all decreased distinctively, while the heights of the first minimum increased with an increasing LiCl. This indicated the degree of unlike charged ions' association decreased with LiCl addition. The coordination numbers were roughly 4, 5, and 6 for Li\({}^{+}\), Na\({}^{+}\), and K\({}^{+}\), respectively. With an increasing LiCl molar fraction, the coordination numbers of the cation-anion pairs all increased, which suggested that cations tended to accommodate more anions. For cation-cation pairs, as shown in Figure 2, the PDF curves of the cation-cation pairs are not as smooth as the ones of cation-anion pairs for the relatively weak association between like charge ions. The first peak positions shifted right and the corresponding height decreased with LiCl addition (except for Li-Li). For Li-Li, \(\mathrm{r_{max}}\) showed an overall increasing tendency, but \(\mathrm{h_{max}}\) increased up to 60% of the LiCl concentration then decreased. The LiCl concentration had more influence on the structure of cation-cation pairs than the cation-anion pairs. The changing rates of \(\mathrm{r_{max}}\) and \(\mathrm{h_{max}}\) for Li-Na and Li-K pairs were smaller than those for Na-Na, Na-K, and K-K pairs, which indicated a larger cation radius difference was a more stable structure even in cation-cation pairs. Figure 1: The experimental set-up for density. For anion-anion pairs, the first peak positions shifted from 4.22 A to 3.75 A across the concentration, while the first peak heights rose from 1.73 to 2.04. The equilibrium distance of Cl-Cl was shortened and the association between Cl-Cl was strengthened. The coordination number of Cl-Cl decreased as LiCl increased, which indicated the closed pack between anions was inhibited. This could be attributed to the significant anion-anion overlap in LiCl salts relative to the other alkali chlorides [23]. temperature range of 900 K to 1200 K. The increasing temperature led to a lower h\({}_{\rm max}\) and an increase of the minima offset, which indicated the looser coordination structure. However, for 1500 K, the r\({}_{\rm max}\) of cation-cation pairs obviously shifted to the right, while the second peak became weaker, which revealed the structure of ions became more liquid-like and disordered. However, the r\({}_{\rm max}\) of cation-anion pairs unexpectedly shifted left. The equilibrium distances of cation-cation pairs increased, however, the cation-anion was the opposite, which means ion clusters were formed. The increasing temperature caused free space in melts to become larger, thus cations drifted apart.