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Abstract:
Colorless crystals of the barium rare earth hydrogarnets Ba-3[RE(OH)(6)](2) (RE = Sc, Y, Ho-Lu) were synthesized under hydroflux conditions with KOH at about T= 200 degrees C starting from the respective RE2O3 and Ba(NO3)(2). Single-crystal X-ray diffraction analysis on these distorted rhombic dodecahedra revealed the cubic space group Ia (3) over bard (no. 230). The crystal structures of the hydrogarnets Ba-3[RE(OH)(6)](2) are discussed and compared with those of other hydrogarnets. The occurrence of additional reflections, which do not fulfill the reflection conditions of Ia (3) over bard, is analyzed and described by Renninger or lambda/2 effects. A correlation is established between the space group adopted by a hydrogarnet and characteristic interatomic distances. In addition, single-crystal structure data of the strontium indium hydrogarnet Sr-3[In(OH)(6)](2) are provided.
