Single-crystal monazite and xenotime structural refinements

Single-crystal monazite and xenotime structural refinements 

SCPO4 bond and contact distances (A) bond angles (°) 

Sc(P04) data after Milligan et al. (1982) Pm(P04) data after Kizilyalli Welch (1976) SCPO4 atomic positions and thermal parameters (A xltf)  

T = exp [-27i (UiihV +U22k b +U33l c +2Ui2hka b cosY +2Ui3hla c cosp +2U23klb c cosa )] where Uy values are the thermal parameters denoted in terms of mean-squared amplitudes of vibration. 

A chain-like structure similar to that exhibited by the monoclinic orthophosphates is also found for the tetragonal zircon type materials. Each of these structure types has four chains in each unit cell, with the principal difference between the xenotime and monazite structural types residing in the difference in the coordination number. The linking of the chains occurs laterally through edge-sharing of adjacent polyhedra (Ni et al. 1995). One view of how the RE ions link to the PO4 tetrahedral units in the xenotime structure is provided by the stereo view of Y(P04) looking down the c axis of the structure shown in 

---