Abstract:

For the first time, Methyl Orange (MO)-doped potash alum (PAS) single crystals of significant size were successfully grown using the slow evaporation technique at room temperature. Powder X-ray diffraction (PXRD) analysis confirmed enhanced crystallinity while retaining the cubic Pa-3 space group. Fourier-transform infrared (FT-IR) spectroscopy verified MO incorporation, with spectral shifts indicating strong host-guest interactions. UV-Vis studies revealed a reduced band gap in the doped crystals. Thermal gravimetric and differential thermal analysis (TGA-DTA) demonstrated improved stability, with the phase transition temperature increasing for pure PAS to MO-doped PAS, attributed to hydrogen bonding and π-π stacking. The final decomposition temperature also rose from 700°C to 991°C, indicating enhanced lattice rigidity. Surface morphology analysis showed fewer defects in doped crystals, confirming superior quality. Z-scan measurements revealed a significant increase in third-order nonlinear susceptibility (χ³: 3.1335 × 10⁻⁷ esu → 5.7571 × 10⁻⁷ esu), along with higher nonlinear refractive index (n₂) and absorption coefficient (β). These results highlight the exceptional structural, optical, thermal, and nonlinear optical properties of MO-doped PAS crystals, positioning them as promising candidates for photonic devices, nonlinear optics, and thermal sensor applications.

Description:

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