Crystal growth and effect of defects on the dielectric properties of ammonium dihydrogen phosphate (ADP) single crystals

Abstract

We report the growth of ammonium dihydrogen phosphate, NH4H2PO4 (ADP) single crystals by slow evaporation method and study of their dielectric property. Furthermore, we correlate the effect of the defects present in the single crystals with the dielectric and other related properties. After determination of the solubility limit of ADP salt in water at different temperatures, the seed crystals were nucleated and grown in the supersaturated solution, which was obtained by cooling the higher temperature saturated solution to room temperature. The phase purity of synthesized ADP crystals was studied by powder X-ray diffraction technique, on the finely ground seed crystals. The seed crystals of appropriate size were used for growth of large crystals and also used for dielectric measurements. Two single crystals with different concentrations of defects were used for the investigation of dielectric property at room temperature. The obtained dielectric data are discussed along with their representation in modulus and impedance formalism to understand the dielectric properties of these crystals. Overall, the low frequency Maxwell–Wagner interfacial polarization was found to increase due to the presence of defects in the ADP single crystals.