Effect of cobalt and dl-malic acid on the growth rate, crystalline perfection, optical, mechanical, dielectric, piezoelectric properties and SHG efficiency of ADP single crystals

Effects of the additions of cobalt (II) acetate hexahydrate and dl-malic acid on the growth and various properties of ammonium dihydrogen orthophosphate single crystals grown by slow evaporation method have been studied. The grown crystals were subjected to UV–vis, microhardness, dielectric, piezoelectric, high resolution X-ray diffraction and SHG studies. UV spectra show good transparency in the entire visible region which is an essential requirement for a nonlinear optical crystal. Vickers hardness study carried out on (1 0 0) face at room temperature shows increased hardness of the crystals added with dl-malic acid compared to the pure and cobalt (II) acetate hexahydrate added crystals. Dielectric constant and dielectric loss were measured for the grown crystals for different frequencies and temperatures. It reveals that the dl-malic acid added ADP crystals have low dielectric loss. Crystalline perfection of the grown crystals was analyzed using HRXRD. Good piezoelectric behaviour was observed for all the crystals. Preliminary measurements indicate that the second harmonic generation efficiency of the dl-malic acid doped crystals is greater than pure and cobalt (II) acetate hexahydrate added ADP.