Structural Analysis and Electric Behavior in Rare Earth Modified Lead Titanate Ferroelectric Ceramics

Study ofAandBsites order in lanthanide-doped lead titanate ferroelectric system

“…It could be expected an increase of [E (1TO)] 2 as well ( Figure 2). The increase of the [(c/a) − 1] values has been explained previously considering the partial occupation of Ln 3+ ions at both A and B sites of the perovskite structure (Mendez-González et al, 2010, 2014Peláiz-Barranco et al, 2010, 2012. For the initial structural model it could be considered that the observed [E (1TO)] 2 behavior as a function of the tetragonal distortion, is also an experimental evidence of the partial occupation of Ln 3+ ions at both crystallographic sites of the ABO 3 structure.…”

“…The structure data were taken from the “Inorganic Crystal Structure Database” (ICSD) (FIZ Karlsruhe, 2014). In the initial structural model, the experimental evidence from the Raman spectra and the results of the previous structural studies suggesting the incorporation of the lanthanide ions at both A and B sites have been considered (Mackie et al , 2010; Mendez-González et al , 2010, 2014; Peláiz-Barranco et al , 2010, 2012). The general nominal composition was Pb 0.94 Ln 0.04 Ti 0.96 Ln 0.04 O 2.98 taking into account that the initial occupancy of Ln 3+ at B site should be in correspondence with the calculated tolerance factor value for these compositions (Mendez-González et al , 2010, 2014; Peláiz-Barranco et al , 2012).…”

“…The structure data were taken from the "Inorganic Crystal Structure Database" (ICSD) (FIZ Karlsruhe, 2014). In the initial structural model, the experimental evidence from the Raman spectra and the results of the previous structural studies suggesting the incorporation of the lanthanide ions at both A and B sites have been considered (Mackie et al, 2010;Mendez-González et al, 2010, 2014Peláiz-Barranco et al, 2010, 2012 An important feature of the observed diffraction profiles, e.g. (00h) and (h00) reflections, is the particular asymmetry that they exhibit.…”

“…The incorporation of rare-earth ions into A and/or B sites is an issue of interest in perovskite oxides titanates (García-Zaldívar et al , 1997; Buscaglia et al , 2000, 2002, 2004; Peláiz-Barranco et al , 2009, 2010, 2012; Mackie et al , 2010; Mendez-González et al , 2010, 2014). Previous studies, in BT ceramics, have shown that Ba 2+ can be substituted by La 3+ and Pr 3+ ions, while fractional occupancy of Gd 3+ and Tb 3+ at the B site has been predicted (Buscaglia et al , 2000).…”

“…Experimental results have shown the partial substitution of smaller ions Dy 3+ , Ho 3+ , and Er 3+ at the B site (García-Zaldívar et al, 1997), and a preferential incorporation of larger ions (La 3+ , Nd 3+ , Sm 3+ , and Gd 3+ ) at the A site of the perovskite structure (Peláiz-Barranco et al, 2009). In PT ceramics, which has been modified with 2 and 8 at% of La 3+ ions, the behavior of the tetragonal distortion and the transition temperature has been found to be consistent with the A-site substitution, while the results for Sm 3+ , Eu 3+ , Gd 3+ , and Dy 3+ ions have suggested the incorporation at both A and B sites (Mendez-González et al, 2010;Peláiz-Barranco et al, 2010, 2012. Recently, a structural study using the extended X-ray absorption fine structure technique and Rietveld refinement on a PT compound modified with 8 at% of Eu 3+ has shown the incorporation of this ion at both sites of the perovskite structure (Mendez-González et al, 2014).…”