Crystal growth and structure determination of the monoarsenate CsBeAsO4

Solid-state synthesis of a new caesium-beryllium monoarsenate and its crystal growth by an original flux process are detailed and followed by a complete crystallographic characterization pointing out it belongs to the well-known stuffed tridymite structural family. Caesium atoms are located in cavities delimited by the chains of tetrahedra and the eight nearest oxygen atoms are distributed over a half-space. It is proposed that the phase transition at 832K proceeds according to a displacive mechanism from Pna2 1 at low temperature to Pnam space group at high temperature