Ferroelectric relaxor behaviour of Ba1-xAx(Ti0.7Zr0.3)O3 and Ba1-xA'2x/3 x/3(Ti0.7Zr0.3)O3 compositions (A = Ca, Sr ; A' = Y, La, Bi)

In order to investigate the effect of A-site homovalent and heterovalent substitution on phase transition in barium titanium zirconium oxide (Ba(Ti0.7Zr0.3)O3), dielectric studies were performed on ceramics of Ba1−xAx(Ti0.7Zr0.3)O3 and Ba1-xA'2x/3 x/3(Ti0.7Zr0.3)O3 compositions (A=Ca, Sr; A′=Y, La, Bi). A preliminary X-ray powder diffraction study has allowed us to determine the limits of solid solution for each composition. A relaxor behaviour appears whatever the value of x in the solid solution domains. The corresponding relaxor characteristics were determined and discussed according to the substituted cation in the twelve coordination number (12-C.N.) crystallographic site. Such new materials are of interest for environmental-friendly applications

Methyl-Specific Isotope Labeling Strategies for NMR Studies of Membrane Proteins

International audienceMethyl groups are very useful probes of structure, dynamics and interactions in protein NMR spectroscopy. In particular, methyl-directed experiments provide high sensitivity even in very large proteins, such as membrane proteins in a membrane-mimicking environment. In this chapter we discuss the approach for labelling methyl groups in E. coli based protein expression, as exemplified with the mitochondrial carrier GGC