Bulk growth, crystalline perfection and optical characteristics of inversely soluble lithium sulfate monohydrate single crystals grown by the conventional solvent evaporation and modified Sankaranarayanan–Ramasamy method

Abstract

Good quality bulk size single crystals of inverse soluble lithium sulphate monohydrate (LSMH) have been grown by the modified Sankaranarayanan–Ramasamy (SR) method. A growth rate as high as 3 mm per day has been obtained for LSMH growth without substantially degrading the optical quality. The rocking curve recorded using the high resolution X-ray diffraction (HRXRD) technique reveals that the crystals grown by this method have a high degree of crystalline perfection. The optical quality of the crystals was studied using an UV-vis-NIR spectrum and the optical constants of the LSMH crystals were calculated. The laser damage threshold value of the grown crystals has been determined using a nanosecond Nd:YAG laser operating at 532 nm. Photoconductivity studies of the grown LSMH crystals reveal a positive photoconductivity behaviour of the grown crystals. The photoluminescence spectrum of the LSMH crystals shows a prominent emission peak at 373 nm. The third order non-linear optical properties of the LSMH crystals were investigated in detail by the Z-scan technique using a He–Ne laser operating at 632.8 nm. The non-linear refractive index (n₂), non-linear absorption coefficient (β) and third order non-linear susceptibility (χ⁽³⁾) of the LSMH crystals were calculated.