High temperature/high pressure synthesis crystal structure of the new corundum related compound Zn_4Nb_2O_9

摘要

A new high-pressure, high-temperature phase, Zn_4Nb_2O_9, has been prepared at T = 1700 ℃, using a pressure of P = 9 GPa. An XRD study based on the Rietveld technique showed the structure to be corundum related (P3-barcl, Z = 2) with the unit-cell parameters a = 5.1864(1) A, c = 14.1445(2) A. The structure consists of close-packed oxygen atoms, with 2/3 of the octahedral interstices occupied by zinc and niobium atoms. the space group was confirmed by micro diffraction and selected-area electron diffraction studies.