Changes of symmetry in the structure of SrCeO3 -BaZrO3 solid solution

Substitution and proton doping effect on SrZrO3 behaviour: high‐pressure Raman study

“…The appearance of a Raman spectrum within the cubic symmetry with the Pm 3 m space group is quite common for the perovskite materials 15–24. For example, such a phenomenon was observed in our previous studies in the case of BaZrO 3 : Ln15, 20; the observed Raman spectrum was assumed to have its origin in the nanodomains with a symmetry different from cubic.…”

“…These studies show a very interesting structural evolution in the case of pure BaZrO 3 with the disappearance of the Raman spectrum at 9 GPa, which is in good agreement with the ideal cubic symmetry (Pm3m), and with the further increase of pressure the reappearance of spectrum due to the transition to the rhombohedral symmetry. Actually, the pure BaZrO 3 possesses a Raman spectrum at RT in contrast with the diffraction results showing that for this material the cubic symmetry prohibits Raman active modes [19] ; the appearance of such a spectrum was explained as due to the existence of the nanodomains with the symmetry different from the Pm3m cubic symmetry [15 -20] as observed for many perovskites, for example the PbMg 1/3 Nb 2/3 O 3 -PbTiO 3 (PMN-PT) solid solutions. [21 -23] The pressure dependence of the Raman spectra of SrTiO 3 was investigated up to 15.5 GPa by Grzechnik et al [24] The authors show that this perovskite undergoes the cubic → tetragonal and then tetragonal → orthorhombic phase transitions near 6 and 15 GPa, respectively.…”

“…b After Ref. [19]. and neutron diffraction results [20,26,27] and group theory prediction (Table 1).…”

Phase transitions in the H+-conducting perovskite ceramics by the quasi-elastic neutron and high-pressure Raman scattering

“…Doping the host lattice and substituting the particular element make the phase transition sequence more complex [26,27]. According to the literature [28] undoped, proton-free BaZrO 3 possesses the ideal cubic structure at the room temperature, and any phase transition is not expected at higher temperatures. The room temperature symmetry of SrZrO 3 is orthorhombic [29], and upon heating, the following sequence of phase transitions was reported: orthorhombic→tetragonal (840°C)→cubic 1,070°C [30].…”

Indirect Raman identification of the proton insertion in the high‐temperature [Ba/Sr][Zr/Ti]O3‐modified perovskite protonic conductors

“…Substituting the particular element make the phase transition sequence more complex [34,35] . According to the literature [36] BaZrO 3 possesses the ideal cubic structure at room temperature and any phase transition is not expected at higher temperatures. The room temperature symmetry of SrZrO 3 is orthorhombic [37] and upon heating the following sequence of phase transitions were reported: orthorhombic < tetragonal (above 840 • C) < cubic (above 1070 • C) [38] .…”