Structural, spectroscopic, and nonlinear optical investigations on a novel nonlinear optical crystal: Hippuric acid doped ammonium di hydrogen phosphate (HAADP)

• Hippuric acid doped ADP (HAADP) crystal was grown by solution growth technique for the first time.
• The crystal is iso-structural with pure ADP with a slight variation in the crystallographic parameters.
• Both pure ADP and HAADP crystals exhibit a high degree of transparency in the 340–1200 nm region.
• The functional groups were assigned using FTIR analysis.
• HAADP crystal possesses 1.5 times SHG efficiency compared with pure ADP.

Transparent single crystals of pure and 1 mol% hippuric acid doped ammonium di hydrogen phosphate (HAADP) were grown from aqueous solution by employing slow evaporation technique. Crystallinity of the grown crystals was studied by powder X-ray diffraction analysis. Both pure ADP and HAADP crystals exhibit tetragonal crystal structure. The bonding structure and molecular associations due to chemical reactions were analyzed by FTIR spectroscopy. It also confirms the functional groups present in the grown crystals. UV–Vis–NIR spectral analysis was carried out to study the optical characteristics of the crystals which reveal that the cutoff wavelength for both pure and hippuric acid doped ADP crystal is around 300 nm. From these spectra it can be clearly inferred that there is an absence of characteristic absorption in the region between 340 and 1200 nm, which is a most desirable property of a material for both SHG and other NLO applications. Second harmonic generation (SHG) test adopting the Kurtz Perry technique revealed that the second harmonic generation efficiency of HAADP is 1.5 times that of pure ADP crystal.

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