Growth, structural, spectroscopic, optical, and mechanical studies of potassium hydrogen phthalate single crystals with glycine as additive

It is proved that glycine admixtured potassium hydrogen phthalate (GKHP) single crystals were effectively developed using solvent evaporation method. Structural studies were carried out using powder X-ray method, which shows that the grown crystal belongs to orthorhombic system with the space group of Pca21. The incorporation of dopant into the crystalline material of pure KHP at different concentrations was established by FTIR spectral analysis. The grown crystals were found to be transparent in the visible section and exhibit a low cutoff wavelength of 300 nm. The optical bandgap energy of the doped crystals was found to be increased from 4 to 4.12 eV. The enhanced refractive indices of the glycine doped KHP crystals from 1.49 to 1.60 could be used for suitable optical waveguide applications. The mechanical microhardness test was carried out on the (010) plane of pure and doped KHP crystals within the applied load range of 15–100 g. The work-hardening coefficient (n) of pure KHP crystal was 2.40. However, the n-value of the doped KHP crystals was estimated to be 2.02, 1.97, and 1.93, respectively. The decreased n-value suggests the moderate hardness nature of the doped KHP single crystals. The nonlinear optical property of the crystals was affirmed by second harmonic generation (SHG) test.