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The crystal structure of Ti2P has been analysed using electron diffraction and high-resolution electron-microscopy techniques. A new unit cell was found, the compound is hexagonal with a = 19.969 (1) and c = 3.4589 (1) Å. The structure was first solved in space group P{\bar6}2m in projection using direct methods on electron diffraction data from the [001] zone axis. A three-dimensional solution was obtained using again direct methods but on a three-dimensional set of electron diffraction data recorded with the precession technique. Ti2P is a distorted Fe2P structure and, based on high-resolution images, it is possible to explain that the tripling of the unit cell is due to the ordering of P vacancies that reduces the symmetry to P\bar6.

Supporting information


Crystallographic Information File (CIF)
Contains datablocks global, I


Structure factor file (CIF format)
Contains datablock I

Computing details top

Data collection: QED (Belletti, Calestani, Gemmi, Migliori, Ultramicroscopy, 2000, 81, 57-65) CRISP (Hovmöller, Ultramicroscopy, 1992, 41, 121-125); cell refinement: GSAS (Larson and Von Dreele 1994); program(s) used to solve structure: SIR97(Cascarano al.,Acta Cryst.,1996,A52,C-79).

(I) top
Crystal data top
Ti2Pc = 3.4589 (1) Å
Mr = 3421.81V = 1194.5 (1) Å3
Hexagonal, P62mZ = 27
a = 19.969 (1) ÅT = 295 K
Data collection top
Philips CM30T
Rint = 0.22
Radiation source: thermoionic electron gunh = 015
precessed electron diffraction scansk = 70
98 measured reflectionsl = 02
Special details top

Experimental. Structure solved by electron diffraction data collected with precession tecnique·Microscope used: Philps CM30T Accelerating voltage 300 kV

Refinement. The structure was solved using direct methods on precessed electron diffraction data. Because of the dynamical effects the quality of the data did not allowed the structure refinement. The errors reported in the atomic positions are just an estimate calculated on the basis of one cycle of refinement.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
TI10.427 (6)0.093 (6)0.5000
TI20.239 (8)0.00000.5000
TI30.330 (6)0.133 (6)0.0000
TI40.472 (8)0.00000.0000
TI50.098 (8)0.098 (8)0.5000
TI60.755 (5)0.424 (7)0.5000
TI70.136 (8)0.00000.0000
TI80.878 (6)0.545 (6)0.0000
TI90.800 (7)0.330 (8)0.0000
TI100.206 (6)0.206 (6)0.0000
TI111.00000.590 (7)0.5000
TI120.335 (6)0.245 (6)0.5000
P30.33 (1)0.00000.0000
P40.444 (7)0.23 (1)0.5000
P50.225 (7)0.117 (9)0.5000
P60.55 (1)0.108 (7)0.5000
P70.328 (10)0.328 (10)0.0000
Bond lengths (Å) top
TI1—TI1i3.21 (15)P3—TI12.57 (10)
TI1—TI23.3 (2)P3—TI32.66 (16)
TI1—TI32.99 (17)P3—TI42.8 (3)
TI1—TI42.99 (15)P4—TI6v2.4 (3)
TI1—TI9ii2.72 (10)P4—TI122.3 (2)
TI2—TI32.92 (8)P4—TI12.6 (2)
TI2—TI72.69 (17)P4—TI8vii2.61 (17)
TI3—TI122.79 (14)P4—TI9ii2.70 (19)
TI4—TI11iii2.92 (14)P4—TI32.74 (11)
TI5—TI5iv3.4 (2)P5—TI22.5 (2)
TI5—TI72.98 (18)P5—TI32.61 (15)
TI5—TI102.76 (11)P5—TI52.4 (2)
TI6—TI6ii3.10 (17)P5—TI72.73 (10)
TI6—TI82.99 (9)P5—TI102.64 (19)
TI6—TI93.00 (19)P5—TI122.40 (14)
TI6—TI9v2.87 (18)P6—TI12.3 (2)
TI8—TI112.75 (8)P6—TI42.59 (8)
TI8—TI12iii2.76 (13)P6—TI6ii2.57 (14)
TI10—TI122.87 (14)P6—TI8ii2.81 (19)
TI11—TI12ii2.86 (19)P6—TI9ii2.69 (19)
TI12—TI12vi3.1 (2)P6—TI11ii2.7 (2)
P1—TI62.49 (6)P7—TI8v2.5 (3)
P1—TI92.71 (16)P7—TI102.47 (17)
P2—TI52.61 (8)P7—TI11v2.35 (10)
P2—TI72.72 (16)P7—TI122.46 (19)
P3—TI22.51 (18)
Symmetry codes: (i) xy, y, z+1; (ii) x+y+1, x+1, z+1; (iii) x+y+1, x+1, z; (iv) x+y, x, z+1; (v) y+1, xy, z; (vi) y, x, z+1; (vii) y+1, xy, z+1.

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