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Study by high resolution electron microscopy and electron diffraction of the La0.03Sr0.255Ba0.7Nb2−yTiyO6−y/2 ferroelectric ceramic

“…[2][3][4][5] Modified Sr 1Ϫx Ba x Nb 2 O 6 and Sr 1Ϫx Ba x Nb 2 O 6 have been reported as materials with a relatively large amount of compositional disorder where a clearly defined transition point cannot be found. Diffusivity of the ferroelectric phase transition is due to the random distribution in the A and B sites, as has been suggested in previous works 6,7 for the La 0.03 Sr 0.255 Ba 0.7 Nb 2Ϫy Ti y O 6Ϫy/2 system. This occupational disorder has been identified as the cause of the structural modulation and related with the incommensurable character found in the TTBs compounds.…”

“…6,7 In Fig. 1, a HRTEM image through the ͓110͔ zone is shown, where it has been possible to determine the interplanar spacings of the TTB cell.…”

Dynamics of normal to diffuse and relaxor phase transition in lead metaniobate-based ferroelectric ceramics

“…The observation just above reinforces a previous suggestion of an apparent association, at least in terms of contribution, between ICS and FE-PE DPT in SBN materials. 16 Accordingly, in contrast to PBNs, the FE-PE DPT plus relaxor behavior found in some SBN solid solutions should respond to the sufficiently Sr 2+ -induced low T C values 10,16,17 so as approaching to overlapping the low-temperature region of the ICS-related diffuse and relaxor dielectric manifestation. Recently, moreover, a work on TTB-structured Ba 2 La x Nd 1−x Nb 3 Ti 2 O 15 ͑BLNNT͒ showed a relaxorlike behavior developing for x = 1, coincidently also within the temperature region of ICS manifestation.…”

“…as previously reported in PBN materials ͑for which the MO-TE transition applied͒, 8 and to incommensurate superstructures ͑ICS͒ ͑extending here up to about 200 K, at least in terms of dielectric dispersion͒, as found to normally develop in PBN 7,13 and parent TTB-structured SBN materials. [14][15][16][17] Figures 2 and 3 now depict the temperature dependence of Ј and Љ, respectively, for Ti 4+ -and Ba 2+ -doped PN samples. In Fig.…”

“…1-4͒, normal-like high-temperature FE-PE phase transitions apply, while the two low-temperature processes, with special attention presently paid to the ICS-associated dielectric dispersion, reveal to be of diffuse and relaxor nature, as also observed elsewhere. [8][9][10]17 In the Fig. 4͑a͒ inset ͑for which the data were presented only up to x = 2.0͒, particularly, T C continuously decreases so as approaching the temperature region of ICS dielectric manifestation.…”