Fluid, hexatic, and crystal phases in terephthal-bis-(4n)-alkylanilines

X-ray scattering studies of single-domain samples of the terephthal-bis-(4n)-alkylanilines (TBnA) are presented. The growth of the bond orientational order parameters in the stacked hexatic SF phase and the scaling relations between them are studied by analyzing the x-ray scattering profiles. The phase transition from the fluid SC to the hexatic SF phase changes from a discontinuous jump in TB5A to a continuous transition in TB7A. The SF-to-SG phase transition is first order. Results of a detailed analysis of the diffuse scattering from the SG phase are reported.