Computational study of ZrSiO4 polymorphs

Using the density functional theory in a local density approximation and generalized gradient approximation (GGA) with a plane wave basis set we have revealed eight new polymorphs of ZrSiO4 within the energy range ∼1eV above the most stable zircon which have higher and lower density than experimentally known zircon and reidite. Two structures, which have both silicon and zirconium atoms sixfold coordinated, orthorhombic AlTaO4-like (alumotantite), and monoclinic PbWO4-like (raspite), have similar energies at a GGA level ∼0.35eV above reidite and density intermediate between zircon and reidite. Among two low-density structures, which can be potentially revealed experimentally in the nanocrystalline thin films, the orthorhombic CaSO4-like form has an energy similar to reidite but with much lower density.