Synthesis, growth, vibrational, optical, laser damage threshold, and mechanical properties of semiorganic third-order nonlinear optical crystal: potassium bis malanato borate

Potassium bis malanato borate (PBMB) C₆H₄BO₈K is a semiorganic nonlinear optical (NLO) single crystal that was developed from an aqueous medium via a slow evaporation process. According to single-crystal X-ray diffraction analysis (SXRD), the PBMB crystal has a space group of \(P\overline{1 }\) $P\overline{1}$ and it belongs to the triclinic crystal system. The crystalline structure of the PBMB crystal was investigated using powder X-ray diffraction (PXRD). The PBMB’s structure and growth axis were used, and high-resolution X-ray diffraction (HRXRD) rocking curve analysis was used to evaluate the lattice quality. The compound’s functional groups were observed using the FTIR spectroscopic method. UV–visible spectrum was used to analyze the crystal’s cut-off wavelength and optical transmission. Using a Nd:YAG laser, the laser-induced damage threshold of the PBMB crystal was determined. The Vickers’ microhardness studies indicate the PBMB crystal belongs to a soft nature. Surface morphology was assessed by etching studies, and the etch pit density was evaluated. The thermal stability of the PBMB compound was examined through TG–DTA, and its third-order NLO behavior was characterized by Z-scan analysis. Additionally, the optical limiting threshold was evaluated.