Crystal structure determination of a new LaPO4 phase in a multicomponent glass ceramic via 3D electron diffraction

Abstract A glass ceramic from the MgO–Al2O3–SiO2 system containing additives of ZrO2, TiO2, La2O3 and P2O5 was investigated. Via x-ray powder diffraction (XRPD) and Transmission electron microscopy(TEM) the crystalline phases present could be identified as MgAl2O4 (Spinel), orthorhombic ZrTiO4 and a polymorph of LaPO4 with a previously unknown crystal structure. The crystal structure of this LaPO4 phase was solved ab initio via 3D ED Data. The polymorph occurs in a distorted barite structure type in the same space group (P21/n) as the stable monazite type polymorph, however the density is higher and the La has a higher coordination number. Furthermore the LaPO4 is present in a spinodal reli…