High temperature phase transitions of CaTiO3 and (Ca0.85Nd0.15)TiO3 by X-ray diffractometry and differential thermal analysis

Structures in the System CaTiO3/SrTiO3

“…It is also possible that Bmmb does not form at all in CaTiO , which would be the case if the b> tilt in Pnma disappeared at the same temperature as the a\ tilt, with one a consequence of the other. We can think of no compelling reason (15), but showed no sign of a transition at a lower temperature. However, this is not conclusive evidence that no such transition occurs, since it would not necessarily be accompanied by a measurable heat capacity anomaly: for instance, the heat capacity measurements of Naylor and Cook (18) on CaTiO showed no evidence of the transition at &1380 K.…”

Space group and crystal structure of the Perovskite CaTiO3 from 296 to 1720 K

“…Vogt and Schmahl [12] reported a direct phase transition from the Pbnm to Pm3m phase and observed no intermediate phase between them. On the contrary, some research groups [8][9][10] reported one intermediate phase between the Pbnm and Pm3m forms. Guyot et al [11] and Kennedy et al [13] suggested two intermediate phases including a Cmcm form between the Pbnm and Pm3m forms.…”

“…It is widely used in electronic ceramic materials and in immobilizing high-level radioactive waste [3][4][5]. The structural phase transition of CaTiO 3 has been studied extensively [6][7][8][9][10][11][12][13][14][15][16][17][18] and reported to undergo structural changes from orthorhombic Pbnm to cubic Pm3m symmetry as summarized in Table 1. Vogt and Schmahl [12] reported a direct phase transition from the Pbnm to Pm3m phase and observed no intermediate phase between them.…”

Strain analysis of phase transitions in (Ca,Sr)TiO3perovskites

“…They showed that the orthorhombic (Pbnm ≡ Pnma) structure, which is stable at room temperature, transforms to the cubic (Pm3 -m) structure via an intermediate tetragonal (I4/mcm) structure at a temperature in the vicinity of 1550 K. An additional intermediate phase with Cmcm symmetry was also considered (Guyot et al 1993;Matsui et al 1997;Kennedy et al 1999a). The literature on phase transitions in SrTiO 3 is substantial, see reviews by Cowley (1996), Salje et al (1998), and Hayward and Salje (1999).…”