Evolution of the ferroelectric transition character of partially deuterated triglycine selenate

Automatically recorded hysteresis loops and dielectric constant data on pur e and partially deuterated triglycine selenate and sulphate are used to cha racterize the transition evolution from quasi-tricritical to clearly first order character. A quantitative assessment of the transition's displacive d egree is made through the first anharmonic contribution to the effective fi eld (g), obtained from hysteresis loop data. This characterization is compl emented with the assessment by means of a generalized Rhodes-Wohlfarth para meter R = (Nk(B)C/4 pi P-S0(2))(1/2) involving the Curie constant C and the saturation spontaneous polarization. P-S0 as done previously by other auth ors.