Structural, optical and dielectric studies of novel non-linear Bisglycine Lithium Nitrate piezoelectric single crystal

• Solution grown BGLiN crystals showed broad violet emission peak in Pl spectra.
• A lower cut-off value and wide band gap were observed in UV absorption spectra.
• The SHG efficiency was found to be 1.5 times that of KDP.
• In dielectric study a broad transition and low value of dielectric loss were observed.
• Piezoelectric charge coefficient was found to be 14 pC/N at RT.

The novel non-linear semiorganic Bisglycine Lithium Nitrate (BGLiN) single crystals were grown by slow evaporation technique. The structural analysis revealed that it belongs to non-centrosymmetric orthorhombic structure. The presence of various functional groups in the grown crystal was confirmed by FTIR and Raman analysis. Surface morphology of the grown crystal was studied by scanning electron microscopy. The optical studies show that crystal has good transmittance (more than 80%) in the entire visible region and a wide band gap (5.17 eV). The optical constants such as extinction coefficient (K), the reflectance (R) and refractive index (n) as a function of photon energy were calculated from the optical measurements. With the help of these optical constants the electric susceptibility (χc) and both the real (εr) and imaginary (εi) parts of the dielectric constants were also calculated which are required to develop optoelectronic devices. In photoluminescence studies, a broad emission band centered at 404 nm was found in addition to a small band at 352 nm. A broad transition (from 29 to 33 °C) was observed with low dielectric constant value. A high piezoelectric charge coefficient (d33) of 14 pC/N was measured at room temperature which implies its usefulness for various sensor applications. The second harmonic generation efficiency of crystal was found to be 1.5 times to that of KDP. From thermo gravimetric analysis and differential thermal analysis, thermal stability and melting point (246 °C) were investigated. The dielectric behavior, optical characterization, piezoelectric behavior and the non-linear optical properties of the Bisglycine Lithium Nitrate single crystals were reported for the first time which established the usefulness of these crystals for various piezo- and opto-electronics applications.

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