Crystal Structure of Iron Nickel Phosphide, Fe1. 7Ni1. 3P, a Schreibersite Extracted from Canyon Diablo Meteorite

Z. KristaUogr. NCS 218 (2003) 391-392 391 © by Oldenbourg Wissenschaftsverlag, München

Crystal structure of iron nickel phosphide, Fe1.7Ni1.3P, a Schreibersite extracted from Canyon Diablo meteorite

O. Moretzki1, Th. Doering1, V. Geist*·1, W. Morgenroth11 and M. Wendschuhm

1 Universität Leipzig, Institut für Mineralogie, Kristallographie und Materialwissenschaft, Schamhorststr. 20, D-04275 Leipzig, Germany " Mineralogisch-Petrologisches Institut und Museum der Rheinischen Friedrich-Wilhelms-Universität Bonn, Poppelsdorfer Schloß, D-53115 Bonn, Germany 111 Universität Bremen, EB 5 Geowissenschaften, Zentrallabor für Kristallographie und angewandte Materialwissenschaft, Klagenfurter Str., D-28359 Bremen, Germany

Received September 29, 2003, accepted and available on-line November 21, 2003; CSD-No. 409732

Discussion The (Fe,Ni)3P single crystals (xenomorph variant named Schreibersite) from the "Canyon Diablo" meteorite with a Fe:Ni-ratio of 1.3:1 (Fe1.7Ni1.3P) show a body centered tetragonal crystal structure with the well known space group 74 typical for meteoritic phosphides. The distribution of Fe and Ni on the three symmetry independent metal positions was determined earlier on Rhabdites from "North Chile" meteorite using a Co-tube with a wavelength near by the Fe absorption edge. This result showed that Ni prefers the M2 and M3 sites avoiding Ml [1] (cf. also [2]). Additional measurements with synchrotron radiation (HAS YLAB at DES Y, Hamburg) near the Fe absorption edge in order to separate Fe and Ni using the anomalous dispersion and the delta synthesis [3,4] showed the same ordering: Fe prefers the Ml and M2 sites whereas Ni prefers the M2 and M3 sites. Con- sidering this fact, the site occupancy factors of the Fe and Ni at- Abstract oms were fixed during refinement [5]. The best R-value is evoked by a distribution with Fe on Ml, Fe/Ni on M2 and Ni on M3. Fe1.7Ni1.3P8, tetragonal, 74 (No. 82), a = 9.049(1) Á, 3 c = 4.4646(9) À, V = 365.6 À , Ζ = 8, Rgt(F) = 0.042, u'ÄreffF2) = 0.093, T= 293 Κ.

Source of material Table 1. Data collection and handling. Single crystals of the phosphides from "Canyon Diablo" were ob- tained by using a solution with HNO3 (3%) and methanol. After Crystal: bronze, wedge-shaped fragment, dissolving the meteorite samples only sulphides, carbides, ox- size 0.04x0.07x0.10 mm Wavelength: Mo Ka radiation (0.71073 Â) ides, phosphides and other crystals remained. The solution with μ: 268.83 cm"1 the crystals was filtered and the phosphides were picked up from Diffractometer, scan mode: Stoe IPDS. φ the filter material. They were prepared and fixed on glas fibres for 20max: 47.8° X-ray experiments. The chemical composition was determined N(hkl)measured, N(hkl)unique: 2173, 282 by electron microprobe analysis (Cameca SX 100). The crystals Criterion for /obs, N(hkl)gt: I0bs > 2 σ(Ιαbs), 274 N(param) refined: 39 are homogeneous and don't show zonations, twinnings or inter- Program: SHELXL-97 [5] growth sections.

Table 2. Atomic coordinates and displacement parameters (in Â^).

Atom Site Occ. χ y ζ Un U22 t/33 Un C/13 U23

Fe(l) 0.0781(2) 0.1079(2) 0.2293(5) 0.007(1) 0.008(1) 0.008(1) 0.0002(7) -0.001(1) 0.000(1) Fe(2) 8 g 0.70 0.3623(2) 0.0338(2) 0.9793(6) 0.004(1) 0.005(1) 0.006(1) 0.0005(7) 0.0008(9) -0.001(1) Ni(2) 8 g 0.30 0.3623 0.0338 0.9793 0.004 0.005 0.006 0.0005 0.0008 -0.001 Ni(3) 8g 0.1680(2) 0.2191(2) 0.7481(6) 0.009(1) 0.008(1) 0.010(1) 0.0023(7) 0.0003(8) -0.002(1) Ρ 0.2930(4) 0.0503(4) 0.482(1) 0.006(2) 0.006(2) 0.008(2) -0.001(1) -0.001(2) 0.002(2)

* Correspondence author (e-mail: [email protected]) 392 Fe1.7Ni1.3P

References

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