ON THE LONG RANGE ORDER PARAMETERS OF CERTAIN A-15 TYPE COMPOUNDS

A review using the structural factor F(S_(6c),y)was carried out for the longrange order parameters of certain A-15 type compounds composed of A_(1-y)B_y cal-culated previously by Van Routh et al.and by Wang et al.from X-ray data.Itwas found that the weight factors in objective functions for analysis and calcu-lation by them seem to be doubtful and the conclusion drawn therefrom aboutthe order-disorder states in these compounds should be reexamined.The criterionwith a minimum error on calculation of the long range order parameters may beproposed by comparison between the composition y from X-ray intensity analysisand y_0 from other accurate determination.Therefore,a neccessary condition maybe suggested for ascertaining the modified weight factors in objective functions,and then the long range order parameters,i.e.,y should be equal to or approxi-mate to y_0.