A Nickel Molybdenum Phosphate with Tunnel: Hydrothermal Synthesis and Structure of (NH3CH2CH2NH3)4 · (NH3CH2CH2NH2) · Na · [Ni2Mo12O30(PO4)(HPO4)4(H2PO4)3] · 6H2O

A new structure–property relationship links atomic displacement parameters (ADP) and the lattice thermal conductivity of clathrate-like compounds. For many clathrate-like compounds, in which one of the atom types is weakly bound and "rattles" within its atomic cage, room temperature ADP information can be used to estimate the room temperature lattice thermal conductivity, the vibration frequency of the "rattler", and the temperature dependence of the heat capacity. X-ray crystallography data, reported in the literature, are used to apply this analysis to several promising classes of thermoelectric materials.