Long-range Order Symmetry Research Articles

Relationship between ferroelectric properties and local structure of Pb1−xBaxZr0.40Ti0.60O3 ceramic materials studied by X-ray absorption and Raman spectroscopies

This paper reports on the structural characterization of Pb1−xBaxZr0.40Ti0.60O3 (PBZT) ferroelectric ceramic compositions prepared by the conventional solid state reaction method. X-ray absorption spectroscopy (XAS) and Raman spectroscopy were used in the probing of the local structure of PBZT samples that exhibit a normal or relaxor ferroelectric behavior. They showed a considerable local disorder around Zr and Pb atoms in the samples of tetragonal or cubic long-range order symmetry. The intensity of the E(TO3) mode in the Raman spectra of PBZT relaxor samples remains constant at temperatures lower than Tm, which has proven the stabilization of the correlation process between nanodomains.

Local structure and hybridization states in Ba0.9Ca0.1Ti1−xZrxO3 ceramic compounds: Correlation with a normal or relaxor ferroelectric character

This paper reports on a multi-edge X-ray absorption analysis to elucidate how the substitution of Ti4+ by Zr4+ ions acts on the local order structure and on the O 2p hybridization states of Ba0.9Ca0.1Ti1−xZrxO3 (BCZT) lead-free ceramic compounds, inducing a ferroelectric evolution from a normal to a relaxor character. Ti, Ba, Zr and O X-ray absorption spectra were measured to probe the local and electronic structure of BCZT samples that exhibit a normal (x<0.18) or relaxor (x⩾0.18) ferroelectric character. X-ray absorption near edge structure results show that the local symmetry and distortion of TiO6, ZrO6 and BaO12 units are not significantly affected by the Ti/Zr ratio, the ferroelectric character or the long-range order symmetry. The assignment of the ab initio density of states associated with the O K-edge enabled a correlation between the decrease in the hybridization between O 2p and Ti 3d states and the ferroelectric character evolution of the BCZT samples. The hybridization states in the ferroelectric relaxor samples exhibit a more symmetric spatial configuration, as occurs with long-range symmetry.