Short-range order, thermal vibration and expansion, and other properties of pseudosymmetric and mixed crystals of small organic molecules - Short-Range order in n- oxyphenazine and in mixed crystals of phenazine- n -oxyphenazine

Abstract

Disorder diffuse scattering has been observed for N -oxyphenazine which indicates the existence of domains of short-range order in (100) planes, of average size 13 A (along b) by 50 A (along c). Along a the alternation of centrosymmetrically arranged molecules is random. Mixed crystals with phenazine show diffuse scattering which indicates that up to about 60 mole % of phenazine can occur in the structure without disrupting these short-range-order domains. Mixed crystals of low N -oxyphenazine content have these molecules arranged randomly in the phenazine matrix. Between these two phases there appears to be a miscibility gap. It is probable that two components, one of which is ordered and the other showing only short-range order cannot form a continuous mixed-crystal series.