Logarithmic correction of the electric susceptibility in paraelectric tris-sarcosine calcium chloride

The dielectric constant tris-sarcosine calcium chloride [(CH₃-NH-CH₂-COOH)₃·{}CaCl₂] has been measured with a relative precision of {~}0.0005 from the transition temperature Tc to Tc+60 K. Over more than 2 orders of magnitude of reduced temperature [(T-Tc)Tc], it follows accurately the logarithmically corrected mean-field behavior of uniaxial dipolar ferroelectrics. It is shown unambiguously that these corrections are superior to a power law. Close to Tc (T<Tc+0.3 K), the dielectric constant becomes affected by roundoff effects. Previous results on tris-sarcosine calcium chloride are reviewed in the light of these new findings.