Structural, vibrational and thermal characterization of phase transformation in l-histidinium bromide monohydrate single crystals

• -histidinium bromide single crystal was grown by slow evaporation technique.
• X-ray diffraction characterize the high-temperature phase transformation.
• The structural phase transformation occur due to loss of water of crystallization.
• The LHBr thermal expansion coefficients exhibit an anisotropic behavior.

l-Histidinium bromide monohydrate (LHBr) single crystal is a nonlinear optical material. In this work the high temperature phase transformation and the thermal stability of single crystals of LHBr was investigated by X-ray diffraction, thermogravimetric analysis, differential thermal analysis, differential scanning calorimetry and Raman spectroscopy. The results showed the LHBr phase transformation of orthorhombic (P212121) to monoclinic system (P 1 2 1) at 120 °C, with the lattice parameters a = 12.162(1) Å, b = 16.821(2) Å, c = 19.477(2) Å and β = 108.56(2)°. These techniques are complementary and confirm the structural phase transformation due to loss water of crystallization.

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