The Ad
(beta-Np) Structure
Last modified 5 April
2001
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- When z = ½ the atoms in this structure are in the
L10 (CuAu) or the A6 (Indium) structure.
- This structure is identical to the B10
(PbO) structure. Pearson's
Handbook, along with the original papers, give the space group
as P421. However, as noted by Structure Reports 15, 121
(1951), the correct space group is P4/nmm. P421 is a
subgroup of P4/nmm.
- The positions here are obtained from Pearson by shifting to
origin by the vector (¾ a,¼ b, 0). This places the origin
at the inversion site.
- Prototype: beta-Np
- Pearson Symbol: tP4
- Strukturbericht Designation: Ad
- Space Group: P4/nmm (Cartesian and lattice coordinate listings
available)
- Number: 129
- Other Compounds with this Structure: PbO,
BiIn, FeSe, FeS, OSn, CuFeTe2
- Primitive Vectors:
- A1 = a X
- A2 = a Y
- A3 = c Z
- Basis Vectors:
| B1 | = | ¾ A1 +
¼ A2 | = | ¾ a X + ¼ a Y | (Np-I) | (2a) |
| B2 | = | ¼ A1 +
¾ A2 | = | ¼ a X + ¾ a Y | (Np-I) | (2a) |
| B3 | = | ¼ A1 +
¼ A2 + z A3 | = | ¼ a X + ¼ a
Y + z c Z | (Np-II) | (2c) |
| B4 | = | ¾ A1 +
¾ A2 + z A3 | = | ¾ a X + ¾ a
Y - z c Z | (Np-II) | (2c) |
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