Growth, characterization and dielectric studies of gadolinium fumarate heptahydrate single crystals

Gadolinium fumarate heptahydrate single crystals were grown by the single gel diffusion technique using silica gel as a medium of growth. Nucleation rate of these crystals was studied corresponding to the effect of various growth parameters. An attempt was made to relate the experimental results with the classical nucleation theory. The crystals were characterized by different physico-chemical techniques of characterization. Powder X-ray diffraction pattern showed that gadolinium fumarate is a crystalline compound and is isomorphous with samarium fumarate heptahydrate crystals. Fourier transform infrared spectroscopy was performed for the identification of water and other functional groups present in the compound. Elemental analysis sugested the chemical formula of the crystals to be Gd2(C4H2O4)3⋅7H2O. The presence of seven molecules of water was also supported by the thermogravimetric analysis. The hydrated compound was found to be thermally stable up to a temperature of about 110 °C and its anhydrous form up to the temperature of 420°C. The thermal decomposition of the compound in the nitrogen atmosphere leads to the formation of gadolinium oxide as the final product. The dielectric properties and AC conductivity of gadolinium fumarate heptahydrate complex were carried out in the frequency range of 20 Hz–3 MHz and over the temperature range of 15–130∘C, both showing a hump at about 95∘C, which could be attributed to water molecules in the crystal boundary.