Date of Award
Wiley, John B.
Tarr, Matthew A.
Rick, Steven W.
Metastable layered perovskites containing interlayer transition metals can readily be obtained by simple ion exchange reactions on receptive hosts, such as those of the Dion-Jacobson and Ruddlesden-Popper structure types. In this work, we focused on adding to the library of layered perovskites by not only creating new compounds, but by also showing their ability to be further manipulated, and by studying the stability of the series through thermal behavior studies.
The reactions with transition metal halides are particularly interesting since they often lead to novel architectures and magnetic behavior. On subsequent heat treatment, these exchange products typically decompose to thermodynamically more stable phases. The newly synthesized spin glass-like material, FeLa2Ti3O10, obtained by ion exchange of Li2La2Ti3O10 with FeCl2 at 350 °C, behaves differently. When heated to 700 °C, the compound undergoes a significant cell contraction (Δc ≈ -2.7 Å) with an increase in the oxidation state of iron present in the interlayer that not been observed before in such compounds. Efforts were also made to synthesize new series of compounds, here MSrTa2O7 (M= Co and Zn), with vacancies in the interlayer that could lead to future topochemical manipulations.
The ability to vary the composition of different phases to form solid-solutions through atomic substitution at the A or B sites with ions of similar or different charge can lead to new structures as well an enhancement of the properties of the original compound or new ones. The synthesis and characterization of the new mixed A-cation containing layered perovskite RbLaNaNb3O10, where La3+ and Na+ share the same site in the perovskite slab and RbLaCaNb2MnO10 that exhibits an ordering of the B site with Mn in the center of the perovskite slab will be presented. Further topochemical manipulation of these phases via ion exchange reactions at low temperatures (< 500 °C), lead to the new series A’LaNaNb3O10 and A’LaCaNb2MnO10 where A’= H, Li, Na, K and CuCl.
Gustin, Lea, "Synthesis and Topochemical Manipulation of New Layered Perovskites" (2016). University of New Orleans Theses and Dissertations. 2149.