Synchrotron X-ray study of Er3Al5O12 and Yb3Al5O12 garnets

Structure factors for Er3Al5O12 and Yb3Al5O12 garnets were measured using f ocused synchrotron X-radiation, with lambda = 0.7500(2) and 0.7000(2) Angst rom, respectively. The difference electron density maps for Er3Al5O12 and Y b3Al5O12 were similar, as expected. This was attributed to the 4f electrons being shielded, which reduces their effectiveness in chemical bonding and the relative position of the rare-earth atoms in the periodic table. The sy mmetry of the difference electron density around the rare-earth atoms was f ound to reflect that of the cation geometry, emphasizing the importance of second nearest-neighbor interactions. This is consistent with the view that oxide-type structures may be regarded as a packed array of cations with an ions in the interstices.