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The atomic coordinates of the crystal structure of nanoscale Ni4Ti3 precipitates in Ni-rich NiTi is refined by means of a least-squares method based on intensity measures of electron-diffraction patterns. The optimization is performed in combination with density functional theory calculations and has yielded an 
symmetry with slightly different atomic positions when compared with the existing structure. The new unit cell offers a better understanding of the lattice deformation from the B2 matrix.
symmetry with slightly different atomic positions when compared with the existing structure. The new unit cell offers a better understanding of the lattice deformation from the B2 matrix.Keywords: Ni4Ti3 precipitation; shape memory alloys; electron diffraction; density functional calculations; multi-slice least-squares method.
Supporting information
 | Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768106036457/lc5049sup1.cif |
 | Text file https://doi.org/10.1107/S0108768106036457/lc5049sup2.txt |
Computing details top
![[Figure 1]](http://journals.iucr.org/b/issues/2006/06/00/lc5049/lc5049fig1thm.gif)
![[Figure 2]](http://journals.iucr.org/b/issues/2006/06/00/lc5049/lc5049fig2thm.gif)
![[Figure 3]](http://journals.iucr.org/b/issues/2006/06/00/lc5049/lc5049fig3thm.gif)
![[Figure 4]](http://journals.iucr.org/b/issues/2006/06/00/lc5049/lc5049fig4thm.gif)
Ni4Ti3 top
Crystal data top
| Ni4Ti3 | V = ? Å3 |
| Mr = ? | Z = ? |
| Rhombohedral, r3:r | Monochromatic radiation, λ = 0.019688 Å |
| Hall symbol: -P 3* | T = 293 K |
| a = 6.6695 Å | × × mm |
| α = 113.838° |
Crystal data top
| Ni4Ti3 | V = ? Å3 |
| Mr = ? | Z = ? |
| Rhombohedral, r3:r | Monochromatic radiation, λ = 0.019688 Å |
| a = 6.6695 Å | T = 293 K |
| α = 113.838° | × × mm |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
| x | y | z | Biso*/Beq | ||
| Ni1 | 0 | 0 | 0 | ||
| Ni2 | 0.5 | 0.5 | 0.5 | ||
| Ni3 | 0.0605 | 0.5931 | 0.7574 | ||
| Ti1 | 0.4989 | 0.1125 | 0.2513 |
Experimental details
| Crystal data | |
| Chemical formula | Ni4Ti3 |
| Mr | ? |
| Crystal system, space group | Rhombohedral, r3:r |
| Temperature (K) | 293 |
| a, c (Å) | 6.6695, 6.6695 |
| α (°) | 113.838 |
| V (Å3) | ? |
| Z | ? |
| Radiation type | Monochromatic, λ = 0.019688 Å |
| µ (mm−1) | ? |
| Crystal size (mm) | × × |
| Data collection | |
| Diffractometer | ? |
| Absorption correction | ? |
| No. of measured, independent and observed (?) reflections | ?, ?, ? |
| Rint | ? |
| Refinement | |
| R[F2 > 2σ(F2)], wR(F2), S | ?, ?, ? |
| No. of reflections | ? |
| No. of parameters | ? |
| No. of restraints | ? |
| Δρmax, Δρmin (e Å−3) | ?, ? |
