Calciotantite
Cooper M A, Hawthorne F C, Cerny P
The Canadian Mineralogist 37 (1999) 1289-1294
Ta-Nb order in the crystal structure of niobium-rich calciotantite
_database_code_amcsd 0005632
6.2261 6.2261 12.280 90 90 120 P6_322
atom      x      y     z  occ  Uiso U(1,1) U(2,2) U(3,3) U(1,2) U(1,3) U(2,3)
Ta1  .35938 .35938   1/2 .698 .0076 .0090  .0090  .0070  .0063  -.0001  .0001
Nb1  .35938 .35938   1/2 .302 .0076 .0090  .0090  .0070  .0063  -.0001  .0001
Ta2     1/3    2/3   1/4 .727 .0082 .0091  .0091  .0062  .0046       0      0
Nb2     1/3    2/3   1/4 .273 .0082 .0091  .0091  .0062  .0046       0      0
Ca      2/3    1/3   1/4      .0065 .0069  .0069  .0058  .0035       0      0
O1    .3757  .4304 .3440      .0097 .0099  .0121  .0075  .0057   .0010  .0025
O2    .7532  .7532   1/2      .0131 .0154  .0154  .0142  .0120   .0006 -.0006
O3      1/3    2/3 .5339      .0092 .0075  .0075  .0127  .0037       0      0