Growth and characterization of A2BX4 and ABX3 type ferroelastic crystals

Abstract

Ferroic is a generic term covering primary, secondary and territory ferroic crystalline materials. In the late 1960 s, the Physicist Aizu coined the term Ferroics and developed a theory of ferroics. The property of mechanical or electrical analogue of ferro magnetism and ferro electricity is called as ferro elasticity. Tetramethylammonium tetra chloro zincate (II) crystals were grown at various pH values. Morphological changes have been observed. The FTIR spectra were recorded for the grown crystal by KBr pellet technique. The presence of functional groups and formation of pure crystal was determined from the FTIR spectrum. Element present in the crystal was analysed quantitatively by ICP. Single crystal X-ray diffraction of the crystal grown at pH 4 and 6.5 was carried out. Thermal analysis of the crystal was made using TG/DTA. Differential Scanning Calorimetric (DSC) study of the crystal was carried out in the temperature range 123 to 423K in heating cycle. The crystal shows maximum number of phase transitions below room temperature. Mechanical hardness of the crystal was studied using Vickers indentation method. Etch patterns are observed on the grown crystals with water as an etchant. Powder X-ray diffraction and single crystal X-ray diffraction studies of the crystal were carried out. TG/DTA analysis show that the crystal is thermally stable up to 573 K. Structural phase transitions was studied by DSC. The crystal shows three transitions below room temperature. TG/DTA was taken to study the thermal analysis of the growth crystals. DSC studies confirm the second order phase transition exhibited by the anhydrous tetramethylammonium cadmium chloride. Also new phase transitions were observed in hydrated crystals. Vickers microhardness was carried out on the grown crystals. All the crystals were found to be softer material and showing reverse indentation size effect. The grown ferroelastic crystals are proposed to be the suitable candidates for industrial applications. newline