data_2002668
_chemical_name_systematic          'Chromium tantalum ditantalate (0.8/0.03/1)'
_chemical_formula_structural       '(Cr.761 Ta.033) (Ta2 O6)'
_chemical_formula_sum              'Cr.761 O6 Ta2.033'
_publ_section_title
;
Hochtemperatursynthese und Kristallchemie der Oxotantalate (Cr2+)0.761
Ta2.095 O6 und Fe Ta2 O6
;
loop_
_publ_author_name
  'Peters, E'
  'Mueller-Buschbaum, Hk'
_journal_name_full
;
Zeitschrift fuer Naturforschung, Teil B. Anorganische Chemie,
Organische Chemie (42,1987-)
;
_journal_volume                    50
_journal_year                      1995
_journal_page_first                712
_journal_page_last                 716
_cell_length_a                     4.7476(11)
_cell_length_b                     4.7497(15)
_cell_length_c                     10.405(3)
_cell_angle_alpha                  90
_cell_angle_beta                   117.152(13)
_cell_angle_gamma                  90
_cell_volume                       208.8
_cell_formula_units_Z              2
_symmetry_space_group_name_H-M     'P 1 21/c 1'
_symmetry_Int_Tables_number        14
_symmetry_cell_setting             monoclinic
loop_
_symmetry_equiv_pos_as_xyz
  'x,y,z'
  '-x,1/2+y,1/2-z'
  '-x,-y,-z'
  'x,1/2-y,1/2+z'
loop_
_atom_type_symbol
_atom_type_oxidation_number
  Ta5+   5.000
  Cr2+   2.430
  O2-   -2.000
loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_symmetry_multiplicity
_atom_site_Wyckoff_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_attached_hydrogens
_atom_site_calc_flag
  Ta1   Ta5+   4 e 0.33175(7) -0.0001(3) 0.33181(3) 0.894(8)  0 d
  Ta2   Ta5+   2 a 0. 0. 0. 0.245(9)  0 d
  Cr1   Cr2+   2 a 0. 0. 0. 0.755(9)  0 d
  O1    O2-    4 e 0.6171(21) 0.2954(19) 0.3257(10) 1.  0 d
  O2    O2-    4 e -0.0273(20) 0.2043(20) 0.1777(10) 1.  0 d
  O3    O2-    4 e 0.3068(19) 0.3100(18) 0.0014(9) 1.  0 d
loop_
_atom_site_aniso_label
_atom_site_aniso_U_11
_atom_site_aniso_U_12
_atom_site_aniso_U_13
_atom_site_aniso_U_22
_atom_site_aniso_U_23
_atom_site_aniso_U_33
  Ta1   0.0104(3) -0.0022(2) 0.0041(2) 0.0099(3) -0.0006(2) 0.0121(3)
  Ta2   0.0162(8) 0.0082(9) 0.0101(6) 0.0134(9) 0.0019(10) 0.0240(9)
  Cr1   0.0162(8) 0.0082(9) 0.0101(6) 0.0134(9) 0.0019(10) 0.0240(9)
  O1    0.019(3) -0.006(3) 0.009(3) 0.012(4) 0.002(3) 0.023(4)
  O2    0.014(3) 0.005(3) 0.007(3) 0.013(4) .000(3) 0.026(4)
  O3    0.014(3) 0.001(3) 0.005(2) 0.012(3) 0.001(3) 0.012(3)
_refine_ls_R_factor_all            0.061