Tridymite: Effect of hydrostatic pressure to 6 kbar on temperatures of two rapidly reversible transitions

Ab initio-assisted assessment of the CaO-SiO2 system under pressure

“…As we may see for instance in Fig. 9a and b the Clapeyron slopes between tridymite and cristobalite polymorphs are well reproduced within the limits of reversal experiments [87,88,91,92]. It should be stressed that, in the case of phase transition with a wide Tref-Tλ gap and a marked Clapeyron slope (such as for the case of cristobalite, outlined in Fig.…”

“…Tridymite. The low-density polymorphs of silica known as "tridymites" occur in a variety of space groups, hence numerous phase transitions have been proposed [89][90][91][92]. The high-T polymorph is closely related to the β-cristobalite structure [93].…”

“…6 and Table 4). Following Berman [42] one could assume that only two phase transitions occur in tridymites, namely those for which "acceptable consensus" exists: a low-to-mean transition occurring at Tλ = 388 K and a mean-to-high transition at Tλ = 440 K [91,92]. We assumed for simplicity that the thermophysical parameters of Fig.…”

“…9. Phase transitions in tridymite (A) and cristobalite (B) as compared with experimental observations [87,88,91,92] (full and empty symbols denote reversals). Black solid and red dashed curves in Fig.…”