X-RAY-DIFFRACTION STUDIES ON SOLID AND MESOMORPHIC PHASES OF 4 MEMBERS OF ALKOXY-CYANOBIPHENYLS

X-ray diffraction studies of four alkoxy cyanobiphenyls (alkyl = nonyl , decyl, undecyl and dodecyl) have been undertaken to determine orient ational order parameters, layer thickness, packing fraction and coeffi cients of HJL type potential. All these values show some odd-even effe ct with the number of chain carbon atoms. Powder X-ray patterns from t hese compounds in solid phase have also been indexed satisfactorily. O rientational order parameters have been fitted to those calculated fro m McMillan's theory by varying the parameters alpha and delta.