| The fruitful chemistry demonstrated in our exploratory synthesis is due largely to the employment of molten-halide fluxes. Halide fluxes, which include alkali and alkaline earth halides, provide a sizable temperature range, 300–1000°C, for synthesis and crystal growth. Incidental salt inclusion is inevitable, which, however, facilitates much variety in novel structural framework formation. Halide fluxes are inexpensive and have proven easy to work with, with respect to retrieving crystals. The chemistry of transition-metal-containing phosphates, arsenates and silicates has been widely studied, mostly by mineralogists. Diverse structural chemistry arises from the versatile bond interactions of MOx polyhedra, M = transition metal (TM), and M′O 4 tetrahedra, M′ = P, As, Si, which are basic building blocks of the structures of targeted compound families in our research.; A number of targeted TM phosphate, arsenate and silicate compounds with interesting structures and physical properties have been prepared through our exploratory synthesis. Conventional high-temperature solid-state and molten-salt flux methods have been employed for crystal growth. Characterization was carried out by single crystal and powder X-ray diffraction, electron microscopy (EDAX), thermal analysis (TGA and DTA), UV-Vis diffuse reflectance and magnetic susceptibility measurements.; In the phosphate and arsenate family of compounds, three copper containing compounds: Na3CsCu2(P/As2O7) 2, Na5RbCu4(AsO4)4Cl 2 and NaCuAsO4; one manganese containing compound: NaMnAsO4, one iron containing compound: KxCs 3−xFe6(AsO4)7; and one niobium containing compound: NaCs2(NbO2)6(AsO 4)4 were synthesized and characterized.; A novel class of open-framework compounds was discovered via salt inclusion These compounds are designated as CU-n (C&barbelow;lemson U&barbelow;niversity # n&barbelow;; n: 1–11). Four members of the class of compounds including, copper based CU-2, AsCu3(M′2O 7)4X3 (AX = NaBr/KBr, RbCl, RbCl/CsCl and CsCl; M′ = P, As), CU-6, ACu5O2(M ′O4)2X (A = Rb, Cs; M′ = P, As; X = Cl, Br, I), and zinc based CU-7, Cs3Zn3(P 2O7)2Cl, CU-10, K3Zn3(P 2O7)2Cl, were synthesized and characterized.; Over the years we have been intrigued by serendipitous, discoveries of novel TM silicates, where fused silica was employed as a reaction container. In spite of utilizing carbon-coated quartz ampoules for preventing attack by molten-halide fluxes, the incorporation of silica in the phase formation was occurred, leading to many accidental discoveries. To control the synthesis, we have proposed the use of copper tubing as an inexpensive reaction container, which provides an inert shield to quartz contamination. Several ternary and quaternary silicates of various transition metals adopting different mineral structures, e.g., Ca3Ti2Si4O12, Garnet, Ba4(TiO2)8Si4O12 , Baotite, Ba2TiOSi2O7, Fresneoite, M2SiO4, where M = Mn, Ni, Olivine, have thus far been synthesized and characterized.; Our study of structure/property correlations should offer insight toward a better understanding of the conducting mechanism in technologically important materials and in the development of new materials wi... |
