The Ba2RE2Si4O13 series is further subdivided into two polymorphs, also showing a dependence on rare earth ionic radius (space group for La3+-Nd3+, and space group C2/ c for Sm3+-Ho3+). Two of the structure types identified are based on dinuclear rare earth units that differ in ...
For samples with approximately AlSi3 composition of the tetrahedral sheet and with no octahedral Al3+, mean M1-O and M2-O octahedral bond lengths correlate very well with the mean ionic radius of the octahedral cations. For these samples, the M1 and M2 sites are found to be very similar ...