The structure of Ba₃(VO₄)₂

Oxide Ion Conductivity in the Hexagonal Perovskite Derivative Ba3MoNbO8.5

“…Ba3MoNbO8.5 has an oxygen stoichiometry between that of the 9R polytype 17 and the palmierite structure 18 . An electron diffraction and high resolution electron microscopy study previously showed that the oxygen defects with respect to the 9R polytype (hhc)3 leads to an ordered distribution of octahedra and tetrahedra in a 3:2 ratio in the cubic layers 19 .…”

“…A bulk conductivity of 2.2 x 10 -3 S cm -1 is observed at 600 C which is comparable to other prominent oxide ion conductors [1][2][3][4][5][6][7][8][9][10][11][12] . Ba3MoNbO8.5 crystallises in a hybrid of the 9R hexagonal and palmierite structures 17,18 . The crystal structure contains both Mo/NbO6 octahedra and Mo/NbO4 tetrahedra with intrinsic oxygen vacancies.…”

Low-temperature sintering-microwave dielectric property relations in Ba3(VO4)2 ceramic

“…Recently, in the MgO-V 2 O 5 system, the Mg 3 (VO 4 ) 2 ceramic which is an orthorhombic structure with a space group of Cmca [5] is reported to have a relatively high Q·f value (Q·f 65,500 GHz) and a low dielectric constant (ε r 9.4) with a τ f value of approximately −90 ppm/ • C when the ceramic was sintered at the temperature of 1050 • C [6]. On the other hand, the crystallographic phase of Ba 3 (VO 4 ) 2 ceramic is known to be a hexagonal structure (R32/m) with lattice parameters a = 5.762Å and c = 21.29Å [7], though the microwave dielectric properties of the ceramic have not been clarified to date. Moreover, in the BaO-V 2 O 5 system, it is known that the Ba 3 (VO 4 ) 2 ceramic is stable below the temperature of 1610 • C [8].…”

Kristallstrukturuntersuchung am Barium-Yanadyl-Vanadat: Ba2(VO)V2O8 / Crystal Structure Investigation of the Barium Vanadyl-Vanadate: Ba2(VO)V2O8

“…U n tersucht wurden Ba3V 0 5 [1]; Ba3V20 8 [2]; B a V 0 3 [3]; Ba2V20 7 [4]; B aV 160 37, Ba2V30 9, Ba3V30 8 [5], Ba6V60 19 [6]; B aV 10O 15 [7]; Ba2V20 5 [8]; Ba3V40 13 [9]; Ba2V 0 4 [10], Ba8V70 22 [11], BaxV80 16 [12] und BaV3O s [13]. Die B ruttofor meln zeigen, daß Vanadium in den Oxidationsstu fen V2+ bis V5+ auftritt.…”