New NMR investigations on the ferroelectric phase transition of TSCC

Abstract

Abstract Tris-sarcosine calcium chloride (TSCC) is a ferroelectric with hydrogen bonds of the type N-H…Cl 1. If protons in the hydrogen bonds are substituted by deuterons, there is no change of the phase transition temperature2,3. On the other hand, if chlorine is replaced by bromine one can observe a drastical reduction of the Curie temperature4. From these two experimental facts the question arises whether a proton ordering process in connection with the phase transition is present in TSCC. Measurements of the proton spin-lattice relaxation times do not allow to draw conclusions about H bond dynamics5. Such conclusions become possible by means of measurements of the shape of 15N NMR lines which is due to15N-1H dipolar coupling in the NH2 group of the H bonds.