Short range order evolution during the nitrification of IVb metals

L. A. MENDOZA-ZELIS; M. A. BAB; L. C. DAMONTE; F. H. SANCHEZ

MATERIALS SCIENCE FORUM

Trans Tech Publications (ttp)

Año: 1999 vol. 312- p. 179 - 184

0255-5476

Nanocrystalline hafnium nitride (HfN) has been produced by milling the metallic Hf powder in a N2 gas flux. By increasing the metallic free surface the solid gas reaction is catalyzed allowing the nitride formation at room temperature. X-ray diffractograms of samples milled during different time intervals indicated the prior formation of hP2 Hf(N) coexisting with cF8 HfN and no evidence of other equilibrium phases like Hf3N2 and Hf4N3. After milling 4h the reaction is completed and under prollonged milling partial oxidation to form Hf7O8N4 starts. The electric field gradient, measured by gamma-gamma perturbed angular correlations technique, evidenced highly disordered Hf environments consistent with a random distribution of N atoms around the metallic ones. A possible mechanism for the observed reaction is discussed.