On determining the state equation of NiX2from the high-pressure spectra shifts and the μkα model

It is shown that the high-pressure state equation and the alpha -P correlation of NiX 2 (X=F, Cl, Br or I) determined by Zhao and Du (1986) from the pressure spectra shifts of NiCl 2 and NiBr 2 based on their mu k alpha model and fitting procedure are not supported by a great many theoretical analyses and experimental facts, and the pressure behaviours of NiF 2 and NiI 2 predicted by them, using the above state equation and the alpha -P correlation, are also doubtful. Thus both the mu k alpha model and their fitting procedure may be held to be faulty and unreliable. Hence, the conclusions based on this model should be rejected.