On the Structural and Luminescent Properties of the M ′ LnTaO4 Rare Earth Tantalates

The structure of has been redetermined and was refined to an value of 0.034. crystallizes in symmetry with , , , . At temperatures >1450°C, will convert by way of a reconstructive transformation into the symmetry of scheelite, and, upon cooling, a second‐order ferroelastic transition (4/mF2/m) to M (fergusonite) occurs. There are significant structural differences between M and which are discussed. compounds exist from . As a host for luminescent ions, is superior to the M modification, as well as all other compounds in the phase diagram.