The paper presents a new data on the crystal structure of K2NaNbO2F4. Single crystals of K2NaNbO2F4, were obtained from the system of KF-NaF-Nb2O5. The compound is cubic, space group Fm (3) over barm (No. 225), and the unit cell parameters are alpha=8.4726(4) angstrom, Z=4, Volume=608.21(5) angstrom(3). The structure was solved by the direct methods and refined to the reliability factors R-1 =0.0116 (wR(2)=0.0302). Its structure can be described as three-dimensional frameworks formed of (0 1 0) Na2Nb2O4F8infinity layers stacked along b axis. In the framework, niobium, oxygen, fluorine atoms form a rare NbO2F4(3-) anion group in an anhydrous solid state environment. The IR spectrum further confirmed the presence of NbO2 and NbF4 groups in the structure. The thermal analysis suggests that K2NaNbO2F4 is an incongruently melting compound.
Chinese Acad Sci, Xinjiang Key Lab Elect Informat Mat & Devices, Xinjiang Tech Inst Phys & Chem, Urumqi 830011, Peoples R China;Chinese Acad Sci, Grad Sch, Beijing 100039, Peoples R China
Li Junjie,Pan Shilie,Tian Xuelin,et al. Dipotassium sodium niobium dioxide tetrafluoride, K2NaNbO2F4, crystal structure and characterization[J]. JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS,2012,73(1):136-138.