TY  - JOUR
AU  - Rösche, Constanze Maria
AU  - Malcherek, Thomas
AU  - Ballaran, Tiziana Boffa
AU  - Paulmann, Carsten
AU  - Angel, Ross
AU  - Gorfman, Semen
AU  - Mihailova, Boriana
TI  - Structural transformations in the (1−x)Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>− xBaTiO<sub>3</sub> solid solution under high pressure: Comparison between x below and above the morphotropic phase boundary
JO  - Physical review / B
VL  - 112
IS  - 18
SN  - 2469-9950
CY  - Woodbury, NY
PB  - Inst.
M1  - PUBDB-2025-04750
SP  - 184102
PY  - 2025
AB  - Single crystals of (1-x)Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-xBaTiO<sub>3</sub> (NBT-xBT) with a composition below (x=0.013) and above (x=0.074) the morphotropic phase boundary (MPB) were studied by in situ high-pressure x-ray diffraction with synchrotron radiation and Raman spectroscopy. We show that both compounds undergo a reversible pressure-induced phase transition to structures with Pnma symmetry, regardless of their symmetry at ambient conditions. The high-pressure phase resembles that recently reported for x<sub>MPB</sub>=0.048, as the critical pressure p<sub>c</sub> gradually increases with x. However, the pathway of developing the high-pressure phase varies with the composition, revealing distinct ways of Ba incorporation into the NBT matrix for the pseudorhombohedral (x=0.013) and tetragonal (x=0.074) phases. For x<x<sub>MPB</sub> the Ba<sup>2+</sup> cations are preferentially accommodated in the tetragonal-type nanodomains existing in the dominant pseudorhombohedral NBT matrix, whereas for x > x<sub>MPB</sub> Ba<sup>2+</sup> is dispersed in both the rhombohedral nanodomains and the dominant tetragonal matrix. Furthermore, for x=0.074 there are incommensurate structural modulations at ambient pressure, which up to p<sub>c</sub> remain unaffected by pressure, but vanish above p<sub>c</sub>.
LB  - PUB:(DE-HGF)16
DO  - DOI:10.1103/p74j-3j8p
UR  - https://bib-pubdb1.desy.de/record/640293
ER  -