title: LuF[SeO3]: the structural chameleon of lanthanoid fluoride oxoselenates(IV).
abstract: LuF[SeO3] is a compound that can easily be obtained by a solid-state reaction of Lu2O3, LuF3, and SeO2 with CsBr as the fluxing agent. The outstanding property of LuF[SeO3] is the appearance of two phase transitions within a range of less than 200 K. With an increase in the coordination number for Lu(3+) from 7 to 8, the triclinic room-temperature modification changes at temperatures below -40 °C to the monoclinic low-temperature or high-pressure phase of LuF[SeO3]. At the same time, room-temperature modification retains the structure but gains higher symmetry at the second phase transition of around +110 °C. This second transition can even be observed under a microscope using polarized light to see twinning lamellae disappear and reappear during this reversible process.
authors.affiliation: Institute for Inorganic Chemistry, University of Stuttgart , Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Lipp
authors.forename: Robert E
authors.initials: RE
authors.lastname: Dinnebier
authors.forename: Thomas
authors.initials: T
authors.lastname: Schleid