Über die Ordnung von B^III und M^V in Perowskiten vom Typ AB^IIIM^VO₆ (A^II  Ba, Sr; M^V  Sb, Nb, Ta)

Abstract

Die Perowskite Ba2BIIISbO6 kristallisieren monoklin (BIII  La, Pr, Nd) bzw. kubisch (BIII  Sm, Eu, Gd, Tb, Dy, Yb, Lu, Y). Die Sr‐Verbindungen, Sr2BIIISbO6, besitzen eine monokline (BIII  Nd, Sm, Eu, Dy), rhombische (BIII  Yb, Lu, Y, Sc) bzw. kubische (BIII  In, Ga) Perowskitstruktur. Mit Intensitätsberechnungen und schwingungsspektroskopischen Methoden ließen sich Abweichungen von einer vollständigen Ordnung der BIII‐ und SbV‐Ionen nachweisen. In den Perowskiten Ba2BIIIMVO6 mit MV  Nb, Ta ist ebenfalls keine vollständige Kationenordnung erkennbar.

A study of the crystal structures and the phase transitions of the ordered double perovskites Sr2ScSbO6 and Ca2ScSbO6

“…To the best of our knowledge, this is the first time that the room-temperature structures of Sr 2 ScSbO 6 and Ca 2 ScSbO 6 are reported. Syntheses of Sr 2 ScSbO 6 have been reported on two occasions [7,17]; however, no structural determination was reported and no space group was identified. In the first study, Sr 2 ScSbO 6 was reported as orthorhombic with unit cell parameters a¼5.678Å; b¼5.691Å; c¼8.021Å [17].…”

“…Syntheses of Sr 2 ScSbO 6 have been reported on two occasions [7,17]; however, no structural determination was reported and no space group was identified. In the first study, Sr 2 ScSbO 6 was reported as orthorhombic with unit cell parameters a¼5.678Å; b¼5.691Å; c¼8.021Å [17]. The second work reported Sr 2 ScSbO 6 as tetragonal, with a¼8.019Å; c¼8.063Å [7].…”

Structures and crystal chemistry of the double perovskites Ba2LnB′O6 (Ln=lanthanide B′=Nb5+ and Ta5+): Part I. Investigation of Ba2LnTaO6 using synchrotron X-ray and neutron powder diffraction

“…Previous reports using conventional (laboratory) X-ray powder diffraction have indicated that the structures of the largest lanthanides (La 3+ -Nd 3+ ) are monoclinic, with smaller lanthanides (Eu 3+ -Tb 3+ ) adopting a tetragonal structure and the smallest lanthanides having cubic symmetry (Dy 3+ -Lu 3+ and Y 3+ ) [4][5][6][7]. However none of these studies determined the complete structures of these perovskites.…”

Synthesis and structural characterisation of the new K2NiF4-type phases, A2In0.5Sb0.5O4(A = Sr, Ba)

“…Nb, Ta). [ see for example [1][2][3][4][5][6][7][8][9][10][11][12][13][14] A related structure to that of perovskite is the K 2 NiF 4 structure in which perovskite-type layers are separated by rock salt layers (figure 1). A wide range of materials with this structure-type have been prepared and studied including the well-known La 2 CuO 4 based superconductor La 2-x Ba x CuO 4 [15][16][17].…”