resumo
Crystal structures of the high-pressure synthesized perovskite phases of the (1-x)BiFe0.5Sc0.5O3-xLaFe0.5Sc0.5O3 (0 = x <= 1) system and their temperature and pressure behaviours were studied using laboratory and synchrotron X-ray diffractions as well as neutron diffraction. At room temperature, the as-prepared phases with x <= 0.05 have an antipolar structure with the Pnma symmetry and with the V2ap x 4ap x 2V2ap superstructure (where ap is the pseudocubic perovskite unit-cell parameter). An incommensurately modulated phase with the Imma(00 gamma)s00 superspace group is observed for 0.10 = x <= 0.33, while a non-polar Pnma phase (V2ap x 2ap x V2ap) is stable when x >= 0.34. The antipolar Pnma phase in the as-prepared samples with composition corresponding to x = 0 transforms into the polar Ima2 one via irreversible annealing-caused transformation accompanied by a formation of a high-temperature intermediate polar R3c polymorph, while the antipolar Pnma phase in samples with x = 0.05 is stable until the decomposition temperature. In the solid solutions with 0.10 = x <= 0.33, increasing temperature was found to result in a reversible transformation of the Imma(00 gamma)s00 phase into a non-polar Pnma one. The transition temperature decreases with increasing x. A hydrostatic pressure of few GPa was also shown to induce a reversible Imma(00 gamma)s00 -> Pnma transformation.
palavras-chave
MAGNETIC-STRUCTURE; BISMUTH; SYSTEM
categoria
Chemistry
autores
Salak, AN; Cardoso, JP; Khalyavin, DD; Barbier, A; Fertey, P; Mikhalev, SM; Olekhnovich, NM; Pushkarev, AV; Radyush, YV; Stanulis, A; Ramanauskas, R
nossos autores
Andrei Salak
Investigador Principal
Sergey Mikhalev
Bolseiro de pós-DoutoramentoProjectos
Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
J.P.C. is grateful to FCT - the Portuguese Foundation for Science and Technology for the financial support through the individual PhD grant SFRH/BD/145281/2019. A.N.S. and S.M.M. acknowledge the financial support of national funds (OE) through FCT in the scope of the frame-work contract foreseen in the numbers 4, 5, and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. The research done in the University of Aveiro was supported by the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MCTES (PIDDAC). The authors also acknowledge SOLEIL for provision of synchrotron radiation at the CRISTAL beamline in frame of the experiment No 20210529. KNMF at the Karlsruhe Institute of Technology is also acknowledged for the provision of the SU-8 compound refractive lenses focusing optic at the CRISTAL beamline.