Neutron powder diffraction studies of transition metal hemicarbides M2C1−x—I. Motivation for a study on W2C and Mo2C and experimental background for an in situ investigation at elevated temperature
✍ Scribed by J Dubois; T Epicier; C Esnouf; G Fantozzi; P Convert
- Publisher
- Elsevier Science
- Year
- 1988
- Weight
- 896 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0001-6160
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✦ Synopsis
The crystallography of hexagonal hemicarbides of the sixth group transition metals (Mo2C, W2C) has been investigated by many workers, and an up to date review is presented herein (Section 1); it appears that controversies concerning the various ordered structures (i.e. C6, ~-Fe2N and (-Fe, N-type phases) exist in the case of W2C, while the crystallography of Mo2C seems to be more consistently established, although one can be surprised that it is significantly different from that of the similar W2C carbide (the E-Fe2N-type phase was not observed in the system Mo-C). These remarks show that a high temperature (up to 2200°C) in situ powder neutron diffraction study on these compounds is needed in order to confirm their high temperature forms. In view of the peculiarities of such an experiment, we have concentrated our attention to detail in this first part the different aspects of our experimental approach (Section 2). The results will appear as part 2 of the present article.