1. a Institute of Crystallography of the Russian Academy of Sciences , Leninskii pr. 59, 117333 , Moscow , Russia
2. b Mineralogisch-Petrographisches Institut, Universität Hamburg , Grindelallee 48 D-20146, Hamburg , Germany
3. c Institute of Solid State Physics of the Russian Academy of Sciences , 142432 , Chernogolovka, Moscow District , Russia