Proton and oxygen-ion conductivity of Ba4Ca2Nb2O11

Crystal structure and imperfection of the perovskite-like proton conductor Ba4Ca2Nb2O11

“…It is established that the crystal structure Ba 4 Ca 2 Nb 2 O 11 is described in the structural type of the double perovskite А 2 (ВВ')О 6 , and is characterized by a cubic cell with space group Fm3m, which corresponds well with x-ray diffraction studies carried out previously [7]. For four formula units А 2 (ВВ')О 6 the following distribution of hydrogen atoms in the positions is characterized: 8с-crystallographic positions are filled with cations of barium (A-sublattice), the cations B-sublattice (niobium and calcium) occupy two crystallographically nonequivalent positions 4a and 4b, the oxygen takes position 24e.…”

Role of the TiO6 octahedra on the ferroelectric and piezoelectric behaviour of the poled PbMg1/3Nb2/3O3–xPbTiO3 (PMN–PT) single crystal and textured ceramic

“…As it can be clearly seen in Figures 7, 8 and 9 the widths of the Raman lines recorded at room temperature for both PMN-PT materials are very characteristic. Namely, the internal modes observed in the middle and high frequency range are rather broad (~60 cm -1 ) whereas the widths of external modes measured in the low wavenumbers are rather thin (~20 cm -1 ) in comparison with those from the higher frequency range as usually observed for many perovskites [43,44]. The presence of broad bands is typical for disorder materials.…”

“…However, one of the recent article [44] suggests that the nanoclusters with lower symmetry are present in pure PMN up to ~550°C. …”

“…It should be stressed that the significant differences between the temperature behaviour of the FWHMs of the lattice modes and those ones attributed to the BOB 6 B vibrations are characteristic for the perovskite materials and confirm our description in terms of two independent sublattices. [32,43,44].…”

Effect of hydration on conductivity of Ba4La x Ca2 − x Nb2O11 + 0.5x (x = 0.5, 1, 1.5, 2) phases

“…Transport properties and hydration of Ba 4 ⎯ x Ca 2 + x Nb 2 O 11 + 0.5х (-0.62 ≤ х ≤ 0.82) phases with the cubic double perovskite structure were stud ied as related to their possible application as proton conductors [1][2][3][4][5]. Also, Ba 4 -х La х Ca 2 Nb 2 O 11 + 0.5х (0 ≤ х ≤ 1.5) phases were studied in terms of proton conductivity.…”