Crystal structures and stability of NaLnF4 (Ln = La, Ce, Pr, Nd, Sm and Gd) studied with synchrotron single-crystal and powder diffraction†
Abstract
Crystal structures of the NaLnF4 materials (Ln = La, Ce, Pr, Nd, Sm or Gd) were studied with , Z = 1) with partial ordering of the
↔ P3. Our observations suggest that the β structure is unstable and that the ordering is a slow process at ambient conditions. Upon compression, β-NaNdF4, β-NaGdF4 and the superstructure NaPrF4 are stable to at least 8 GPa with no evidence for any pressure-induced disorder–order phenomena.