Effect of carboxylic acids on optical and thermal properties of KDP and ADP single crystals

Three carboxylic acids - fumaric acid, glutamic acid and succinic acid were mixed with KDP and ADP to grow single crystals grown by the natural slow evaporation method. Transparent crystals were harvested in a period of one month. The phase purity of the crystals was identified using powder XRD. FTIR spectra were recorded to identify the vibrational activity of the various functional groups present in the title compounds, also the thermal properties of material were studied. The cutoff wavelength of the grown crystals are in the range of 500-565 nm. The optical bandgap energies of the grown single crystals are increased when compared to pure carboxylic acids, which shows that the complex maybe formed by the weak interactions. Formation of these compounds resulted in high bandgap and good SHG efficiencies which are caused by more number of weak interaction between carboxylic and phosphates.