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Abstract
The smectic A (SA)-chiral smectic C (S*C) transition in binary mixtures of methylchloropentanoyloxy heptyloxybiphenyl (C7) and butyloxyphenyl decyloxybenzoate (10O.4) changes from first order to second order as a function of X, the mole per cent of 10O.4. High resolution heat capacity measurements show that the Cp behaviour is well-described by Landau mean field theory. Classical tricritical behaviour is observed near X tc ≃ 10·6 and the coefficient b of the quadratic term in the free energy varies like (X - X tc) in good agreement with results from polarization data.