title: Layered graphitic carbon host formation during liquid-free solid state growth of metal pyrophosphates.
abstract: We report a successful ligand- and liquid-free solid state route to form metal pyrophosphates within a layered graphitic carbon matrix through a single step approach involving pyrolysis of previously synthesized organometallic derivatives of a cyclotriphosphazene. In this case, we show how single crystal Mn(2)P(2)O(7) can be formed on either the micro- or the nanoscale in the complete absence of solvents or solutions by an efficient combustion process using rationally designed macromolecular trimer precursors, and present evidence and a mechanism for layered graphite host formation. Using in situ Raman spectroscopy, infrared spectroscopy, X-ray diffraction, high resolution electron microscopy, thermogravimetric and differential scanning calorimetric analysis, and near-edge X-ray absorption fine structure examination, we monitor the formation process of a layered, graphitic carbon in the matrix. The identification of thermally and electrically conductive graphitic carbon host formation is important for the further development of this general ligand-free synthetic approach for inorganic nanocrystal growth in the solid state, and can be extended to form a range of transition metals pyrophosphates. For important energy storage applications, the method gives the ability to form oxide and (pyro)phosphates within a conductive, intercalation possible, graphitic carbon as host-guest composites directly on substrates for high rate Li-ion battery and emerging alternative positive electrode materials.
authors.affiliation: Department of Chemistry, Faculty of Science, Universidad of Chile, Casilla 653, Santiago, Chile. cdiaz@uchile.cl
authors.forename: Carlos
authors.initials: C
authors.lastname: Díaz
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Valenzuela
authors.forename: Vladimir
authors.initials: V
authors.lastname: Lavayen
authors.forename: Colm
authors.initials: C
authors.lastname: O'Dwyer