An Electron Diffraction Study of Sn/P and Interstitial Ni Ordering in Ni1+mSn1−xPxB8-type Solid Solutions

✍ Scribed by S. Furuseth; A-K. Larsson; R.L. Withers

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 1018 KB
• Volume: 136
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7683

✦ Synopsis

Electron diffraction is used to investigate Sn/P and interstitial Ni atom ordering in the apparent wide range, non-stoichiometric Ni 1 ؉ m Sn 1 ؊ x P x ternary B8-type solid solution. Two complex modulated structures are found to exist in a limited area of the solid solubility range, described by compositions around Ni 1.1 Sn 0.7 P 0.3 . This region of the high temperature Ni 1 ؉ m Sn 1 ؊ x P x , B8-type phase field had previously been found to separate out as an isolated B8 type phase region at low temperatures. A complex, long range ordered triclinic superstructure phase is found for specimens quenched from lower temperatures and a plausible structural model, based on ordering of NiP 3 Sn 2 trigonal bipyramidal clusters, proposed. The underlying B8 subcell remains metrically hexagonal so that there are at least 12 distinct twin variants whose B8 sublattice reflections overlap exactly. The diffraction patterns characteristic of specimens quenched from higher temperatures are compatible with a multiply twinned microdomain model.