John N. Lalena

Inorganic materials synthesis and fabrication

Preface. 1. Crystallographic and Microstructural Considerations. 2. Chemical Energetics and Atomistics of Reactions and Transformations in Solids. 3. Solid - Vapor Reactions. 4. Solid - Liquid Reactions. 5. Solid - Solid Reactions. 6. Nanomaterials Synthesis. 7. Materials Fabrication. Appendix A1: General Mechanical Engineering Terms. Appendix A2: Green Materials Synthesis and Processing. Index.

Divalent ion exchange of alkaline-earth cations into the triple-layered perovskite RbCa2Nb3O10

Abstract Ion exchange reactions between the Dion-Jacobson-type, triple-layered perovskite RbCa 2 Nb 3 O 10 and calcium, strontium, and barium cations were investigated. Exchange occurs in all systems, but only the strontium and barium systems form stable compounds. The final products, Rb 1−x Sr x/2 Ca 2 Nb 3 O 10 (x = 0.45) and Rb 1−x Ba x/2 Ca 2 Nb 3 O 10 (x = 0.55), are isostructural with the parent. Unit cells contract upon replacement of rubidium with the smaller, more highly charged cation. The effect of layer contraction in directing the extent of exchange is discussed.

Low-Temperature Multistep Topotactic Routes to New Mixed-Valence Perovskites

Multistep topotactic routes are exploited to introduce mixed-valency into mixed-metal oxides at low temperatures (≤ 350°C). A new set of single- and triple-layered perovskites, Na 1-x-y Ca x/2 LaTiO 4 and Na 2-x+y Ca x/2 La 2 Ti 3 O 10 , respectively, has been prepared by a combination of ion exchange and reductive intercalation. The single-layer series are metastable compounds. The magnetic and electronic behavior of the triple-layer titanate is consistent with Anderson localization effects, while those of the single-layer materials are more complex; samples demonstrate “Hurd-like” conductivity and an unusual magnetic response. The details of the synthesis and characterization of these materials are presented and their magnetic and electronic behavior discussed.