Compositional influence of local and long-range polarity in the frustrated pyrochlore system Bi_2−xRE_xTi₂O₇(RE = Y³⁺,Ho³⁺)

Abstract

Structural distortions such as cation off-centering are frustrated in the pyrochlore structure due to the triangular arrangement of cations on the pyrochlore lattice. This geometric constraint inhibits a transition from...

Synthesis and characterization of cerium (III) and (IV) compounds

“…Even though a blue color change did occur in both instances, the 1 H NMR did not contain proton peaks for C5H5. Additionally, 19 F NMR for both cases provided peaks at around 14 ppm which do not match with the reported 19 60 The Ce-Br and Ce-I bond distances of 2.8109 (5) and 3.0715 (6) , respectively, are longer than those in [CeN(SiMe3)2)3)X] complexes of 2.766(2) , X = Br, and 2.9980(2) , X = I. 61 The widening of the X-Ce-O bond angle is observed moving from 104.5(3) to 105.68 (11) as the halide becomes larger.…”

“…Despite some of these assumptions, the lanthanides still were able to earn their prestige with time. The lanthanide series has been extremely beneficial for our society as they have found great applications as phosphors 3 , optical coatings 4 , Pb 2+ -free alternatives 5 , and catalysts 6 .…”

Vacancy-Driven Disorder and Elevated Dielectric Response in the Pyrochlore Pb1.5Nb2O6.5

“…The A-site atoms can displace in a 2-in-2-out fashion, resulting in an ordered P4̅3 m model, , illustrated in Figure b. Alternatively, their local displacements can be characterized with a beta-cristobalite model, ,, in which the tetrahedral sub-units can rotate about the corner-shared vertices (depicted in Figure c,d). The cristobalite-like displacements can be described with either the P 4 3 2 1 2 (#96) or the P 4 1 2 1 2 (#92) space group, which are structural enantiomers and result in equivalent models for powder experiments.…”