Effect of Ni2+ doping on structural, optical, mechanical and dielectric properties of ammonium dihydrogen phosphate (ADP) single crystals: A novel NLO material

Owing to its exceptional applications in nonlinear optical devices, ammonium dihydrogen phosphate (ADP) is considered as potential candidate in modern era of hi-tech applications. Therefore, in the present work we have grown good quality single crystals of pure and Ni2+ doped (1, 2.5% and 5%), ADP using slow evaporation technique. X-ray study has been carried out in order to see the effect of dopant on the structural parameter of ADP. The UV-vis-NIR studies confirmed that 1.0 mol%, 2.5 mol% doped crystals have high transmittance compare to 5.0 mol% Ni2+ doped ADP crystals. Surface studies have been carried out on pure and doped crystals. Typical striations are observed on the (100) faces of pure and doped crystals, suggest that the growth occurs by 2D nucleation. The microhardness studies of pure and doped crystals carried out at different loads. The hardness of 5.0 mol% Ni2+ doped crystals shows higher hardness value compare to 1.0 mol%, 2.5 mol% doped crystals. The mechanical properties such as fracture toughness (Kc), brittleness index (Bi) and yield strength (σy) are presented. The dielectric studies were carried out in the high frequency range (1-6 MHz) and all the results indicate that the grown crystals are of good quality.