| The studies on complex polar intermetallic phases were motivated by the desire to explore the structural chemistry of 'salt-like' intermetallics along the Zintl border (an empirical boundary between group 13 and 14 elements) and discover new aid novel chemical bonding, as well as unusual crystal structures. This work focuses on the structural and chemical bonding of polar intermetallics.;Our exploratory research in this area has lead to the discovery of a number of new polar intermetallic systems. This includes a series of new quaternary polar intermetallic compounds with intergrowth structures: Ca8AgInGe 8, Ca16Ag4Ge11.14(1)Sn4.86(1) . Ca28Ge15.06(2)Pd8Sn12.94(2) , Ca28Ag8.77(1) Si27.23(1). Their crystal structure features parallel anionic sheets pillared by Ge zigzag chains to form a complex network. The pillared-layer intermetallic network is analogous to the well-known organic-based pillared layer metal oxide compounds.;Three new calcium nickel germanides---CaNiGe, Ca2Ni 3Ge2 and Ca4Ni4Ge3 were also discovered in Ca-Ni-Ge system. All three new ternary Ca-Ni-Ge phases feature two-dimensional network of Ni and Ge separated by the calcium atoms. These add to the variety of layered nickel germanides in the alkaline earth metal system.;The new polar intermetallic phase. La2CdGe2, features a unique square planar [CdGe4/2]6- network that can be derived from a pairing distortion of the square planar CdGe2 layers analogous to the CuO2 sheets of the high-Tc cuprates. A new family of interstitial compounds Ln3Tr2Ox (Ln = La, Ce; Tr = Si, Ge) that are all based on the ubiquitous U3Si 2 structure type were also synthesized. These interstitial compounds. Ln3Tr2Ox, expand the interstitial chemistry of the U3Si2-type, following that of Mn5Si 3, and afford an effective means of tuning properties of its host structure.;Two newly discovered rare earth suboxides, La10Si8O 3 and Ce10Si8O3, feature the concurrence of metal-metal bonding and complex Zintl anions with the Si6, planar ring that is isoelectronic and analogous with benzene. Another novel rare-earth suboxide, La26Ag6Ge18O5, features the [La18O5] clusters that have never been reported in rare-earth metal suboxides and very complex anion network. |
