Systematics of Crystalline Oxide and Framework Compression

A universal equation of state of solids is one of the far goals of condensed matter science. Here, it is shown that within pressures of 2-100 GPa, the compression of oxides and oxide-based networks follows a linear relation between the molar volume and the combined ionic volume that is based on the pressure-dependent crystal radii at any pressure. This relation holds for simple and complex oxides and modified networks such as alumosilicates, beryllosilicates, borates, and empty zeolites. Available compression data for halides and metal-organic frameworks are also consistent with this relation. Thus, the observed relation also serves as a measure for pore-space filling in cage structures.