COL  ICSD Collection Code 79684
 DATE Recorded Oct 14, 1996; updated Jan 19, 1999
 NAME Iron ditantalum hexaoxide
 MINR Tapiolite
 MINR Ferrotapiolite
 FORM Fe Ta2 O6
      = Fe O6 Ta2
 FORM Fe (Ta1.8 Nb0.2) O6
 TITL Cation ordering waves in trirutiles. When X-ray crystallography 
      fails?
 REF  Acta Crystallographica A (39,1983-)
      ACACE 51 (1995) 514-519
 REF  Arkiv foer Kemi
      ARKEA 28 (1968) 375-387
 AUT  Hansen S, Landa-Canovas˙A, Stahl˙K, Nilsson˙J
 CELL a=4.752 b=4.752 c=9.254 ŕ=90.0 á=90.0 ç=90.0
      V=208.9 D=7.82 Z=2
 SGR  P 42/m n m    (136) - tetragonal
 CLAS 4/mmm (Hermann-Mauguin) - D4h (Schoenflies)
 PRS  tP18
 ANX  AB2X6
 PARM Atom__No OxStat  Wyck ---X--- ---Y--- ---Z---  -SOF-
      Fe     1  2.000    2a  0.      0.      0.        0.512(8)
      Ta     1  5.000    2a  0.      0.      0.        0.488
      Fe     2  2.000    4e  0.      0.      0.3327    0.244
      Ta     2  5.000    4e  0.      0.      0.3327    0.756
      O      1 -2.000    4f  0.312   0.312   0.
      O      2 -2.000    8j  0.308   0.308   0.33
 WYCK j f e a
 ITF  Fe  1   B=0.93(9)
 ITF  Ta  1   B=0.93(9)
 ITF  Fe  2   B=1.09(6)
 ITF  Ta  2   B=1.09(6)
 ITF  O   1   B=1.2(4)
 ITF  O   2   B=1.6(3)
 REM  REF (refinement of earlier measured intensity data)
 REM  M PDF 23-1124, mean M-O: 2.05, 2.02, model I (big-small-small)
 REM  M For random Fe/Ta distribution R=0.136
 REM  M Rutile structure type
 RVAL 0.076
 TEST Calculated density unusual but tolerable. (Code 23)