Ionic polarizabilities in crystals at high pressures

Pressure dependence of ionic polarizabilities in crystals

“…For fcc oxides (Table 3), α + values are assumed equal to those of the corresponding fluorides [21], similarly to what was done for alkali halides. obtained via the Clausius-Mossotti equation is given in Table 3 and shows the nontransferability of this magnitude for different oxides, as expected; the same can be seen for…”

“…A. O. Bruno*, and M. C. Monard** Method 1. The empirical method we proposed previously [8] for the study of anion polarizabilities at high pressures can be seen to be applicable to cations as well [21]. As we have shown, the need of considering ∂α + / ∂ p ≠ 0 is important even for cations such as K + , Rb + , and Cs + .…”

“…Method 2. The method we introduced previously [21,23] is based on the well-known relation α + / α -= ( r + / r -) 3 :…”

“…Given that ∂α + /∂p is the same as for the corresponding fluorides [21] and that our preliminary estimations of -∂ /∂p (MgO = 0.72, CaO = 1.91, SrO = 3.21, and BaO = 4.78, all in 10 -32 m 3 /GPa) using the evaluated ab initio vs. R curve for MgO [6] are similar to those obtained via method 1, one may propose values of ∂α total /∂p (see the last column in Table 3). …”

“…It is therefore important to have theoretical methods to evaluate the polarizabilities based either on data only at p = 0 [8], or on high-pressure data of the solid [21], or of other solids that have either a cation or an anion in common with the one we are studying [8,21]. These two aspects will be discussed in the next section.…”