The ferroelectric phase transition in tridymite type BaAL₂O₄studied by electron microscopy

Weak ferroelectricity and low-permittivity microwave dielectric properties of Ba 2 Zn (1+x) Si 2 O (7+x) ceramics

“…The strip-type domain structure in Fig. 5(d), which was also observed in the BaAl 2 O 4 and Ba 2 ZnSi 2 O 7 FEs, is another sign of weak ferroelectricity [2,46].…”

Giant thermal vibrations in the framework compoundsBa1−xSrxAl2O4

“…In electron diffraction experiments of BaAl 2 O 4 , a characteristic honeycomb-type diffuse scattering pattern has been reported over a wide range of temperatures below 800 K. 21,22 A similar pattern was also observed in Ba 1−x Sr x Al 2 O 4 with x = 0.4. 23 In the structural refinements of the x = 0.4 sample, significant disorder was noted in the two oxygen sites, O1(2d) and O2(6g), in the initial model of P 6 3 22 symmetry, as shown in Fig 1(a).…”

A Fluctuating State in the Framework Compounds (Ba,Sr)Al2O4

“…In the electron diffraction patterns of its high-temperature phase, characteristic honeycomb-like diffuse scatterings (honeycomb pattern) have been observed16. Because the scattering intensities are strongly dependent on the temperature, the characteristic honeycomb pattern may stem from an intrinsic structural fluctuation associated with a soft mode.…”