Abstract Ammonium dihydrogen phosphate (ADP) is an excellent inorganic nonlinear optical crystal used in different device applications. In the present study, pure and Urea doped ADP crystals were grown using a slow evaporation solution growth technique. The grown crystals have been subjected to various characterization studies such as powder X-ray diffraction, ultraviolet visible (UV Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, photoluminescence (PL) study and refractive index (R.I.) measurement. By using the powder X-ray diffraction technique, the structural characteristics of the pure and Urea-doped ADP crystals were identified. The crystallite size for pure ADP was found to be 104.9 nm, and it was reduced to 55. nm after doping with 10% Urea. The consequence of Urea on the optical transparency of ADP crystals was examined within 200–1100 nm by means of UV–vis spectral analysis. The direct band gap varied from 4.89 to 6.23 eV, and the indirect band gap varied from 4.21 to 5.87 eV. Additionally, a decrease in the value of the refractive index from 1.46 to 1.24 is observed for the doped ADP crystals. Fourier transform infrared (FTIR) studies confirm the presence of functional groups in the crystals. In the PL spectra, the intensity of blue emission is enhanced with increasing Urea concentration. The second harmonic generation (SHG) efficiency of 10 mol % Urea doped ADP is improved 1.21 times compared to the reference KDP compound. The second harmonic generation (SHG) efficiency of the ADP crystal was found to be decreased at higher concentrations of Urea doping.Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.Checked. Authors and their respective affiliations are correct.
Chatra et al. (2026) studied this question.