Ferroelectric Glycine Research Articles

Linear birefringence in ferroelectric glycine phosphite and deuterated glycine phosphite

Linear birefringence changes were measured with the rotating analyzer method for the glycine phosphite crystal and its deuterated analogue in the vicinity of ferroelectric phase transition. Continuous character of the phase transition was assured. Power rule was found as fulfilled only in close vicinity of Tc. Evident isotope effect was denoted: deuteration changes Tc from 225 to 324K.

Dynamics of a glycine molecule in a new ferroelectric glycine phosphite studied by proton NMR

The second moments of the proton magnetic resonance lines and relaxation times in the laboratory frame T 1, in polycrystalline glycinum phosphite (NH + 3CH 2COOH)(H 2PO − 3) were measured. The proton spin-lattice relaxation measurements reveal one minimum due to the C 3 reorientations of the amino groups of glycinum cations. Analysis of the relaxation data yields the activation energy barrier of 28.7 kJ mol −1. Second moment measurements confirm the phase transition at T c =224 K known from different studies. The molecular mechanism of the order–disorder phase transition is discussed.

Dielectric Dispersion in Ferroelectric Glycine Phosphite

Dielectric Dispersion in Ferroelectric Glycine Phosphite

Effect of Hydrostatic Pressure on the Phase Transitions in Ferroelectric Glycine Silver Nitrate and Deuterated Glycine Silver Nitrate

Effect of hydrostatic pressure on the ferroelectric phase transitions in glycine silver nitrate (NH 2 CH 2 COOH·AgNO 3 ; GSN) and its deuterated analogue(DGSN) was studied by means of dielectric measurements. The Curie temperatures decrease with increasing pressure by a relation T c = T c 0 + K p +γ p 2 . Parameters T c 0 , K , and γ are determined as -57.1°C, -17.1 deg kbar -1 , and 1.3 deg kbar -2 , respectively, for GSN and -42.7°C, -20.2 deg kbar -1 , and 1.7 deg kbar -2 , respectively, for DGSN. Considerable decrease in Curie constants was observed both in GSN and in DGSN as pressure increases.

Domain Wall Caught in Dislocations in Ferroelectric Glycine Sulfate Crystals

Simultaneous observation of both dislocation etch pits and ferroelectric domain walls was made on b-face of ferroelectric glycine sulfate crystals by etching technique with water. Negative end of the domain is pebbled while positive end is smooth. The dislocation etch pits are well discernible from the “pebbles” on the etched face. It was revealed that under applications of a d.c. electric field of about 30 v/cm a domain wall is caught in dislocations during the domain wall motion resulting in zig-zag shape. Evidences were obtained that also in as-grown crystals domain walls were caught in dislocations. It is assumed that dislocations in which a domain wall is caught are edge dislocations emerging out of b-face.

Growth and Domain Structure of and Irradiation Effect on Ferroelectric Glycine Sulfate Single Crystals

Growth and Domain Structure of and Irradiation Effect on Ferroelectric Glycine Sulfate Single Crystals

Structures of Ferroelectric Domains in Triglycine Sulfate

Domain structures in ferroelectric glycine sulfate are studied by etching in various alcohols. Methyl alcohol etches the head of polarization more readily than the tail end, and gives, in a relatively short time, clear domain patterns. Moreover, this etchant etches the (001) surface very slowly and after a long time delineates the arranging manner of domains along the polarization axis. Domain boundaries have cylindrical surfaces parallel to b axis, but the sections perpendicular to the axis are quite indefinite in dimensition and direction. Domain terminated with a rounded tip in the antiparallell domain was observed. Crystal imperfection seems to have a considsrable effect on the domain structure of this crystal. Some preliminary studies of domain wall motion under the application of electric field are also reported.