Gamma irradiation effects on crystalline and optical properties of pure and doped Potassium Hydrogen Phthalate (KHP) single crystals

The undoped and urea doped semi-organic nonlinear optical Potassium Hydrogen Phthalate (KHP) crystals were grown by solution growth slow evaporation technique at room temperature. Grown crystals were irradiated with gamma rays using 60Co radioactive source. Grown crystals were irradiated with different dose from 100 krad to 5 Mrad. Irradiated and unirradiated crystals were subjected to powder x-ray diffraction and lattice parameters were calculated. It was also observed, slight colour change of crystals with increase in the dose of irradiation. The functional groups of irradiated undoped and urea doped KHP crystals were identified from FTIR spectral studies. The UV-vis spectrum reveals an increase in the optical absorption with increase in gamma dose in undoped and doped KHP. From Tauc the plot optical band gap is estimated and found to decrease with increase in gamma dose. Second harmonic generation (SHG) efficiency was confirmed by Kurtz-Perry powder method and SHG values decreases with increase in radiation dose.