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

The dielectric constant tris-sarcosine calcium chloride [${(\mathrm{C}{\mathrm{H}}_3-\mathrm{N}\mathrm{H}-\mathrm{C}{\mathrm{H}}_2-\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H})}_3$·Ca${\mathrm{Cl}}_2$] has been measured with a relative precision of ∼0.0005 from the transition temperature $T_c$ to $T_c+60\mathrm{}$ K. Over more than 2 orders of magnitude of reduced temperature [$\frac{(T-T_c)}{T_c}$], 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 $T_c$ ($T<\mathrm{}{T}_c+0.3\mathrm{}$ 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.