Mixed (NH4)2Mn0.47Cu0.53(SO4)2(H2O)6 Tutton salt: A novel optical material for solar-blind technology

In this paper, a novel mixed Tutton salt (NH₄)₂Mn_0.47Cu_0.53(SO₄)₂(H₂O)₆ obtained in single crystal form is described. Their structural, thermal, electrical, and spectroscopic properties have been examined, and their possible uses are discussed. The salt crystallizes in a monoclinic symmetry (P2₁/c) and exhibits thermal stability between 300 and 333 K. Above this temperature, the crystal undergoes phase changes associated with dehydration and crystallization processes. 231 optical phonons distributed between 50 and 4000 cm⁻¹, calculated through density functional perturbation theory, were used to accurately assign vibrational modes in experimental FT-IR and Raman spectra. Additional computational studies using Hirshfeld surfaces have revealed that H⋯O/O⋯H and H⋯H intermolecular contacts are crucial interactions for stabilizing the crystal lattice. Electrical characteristics (resistivity = 1160 MΩ cm; capacitance = 3.6 pF) and optical data (bandgap = 4.27 eV) depict a typical behavior of nonpolar dielectric materials. UV-Vis-NIR transmittance spectrum has shown deep light blocking in the UV-C and Vis/NIR spectral regions and high transmittance levels (reaching 98.5 %) in the UV-B/-A/Vis range. The photoresponse findings point out that (NH₄)₂Mn_0.47Cu_0.53(SO₄)₂(H₂O)₆ is a promising light-absorbing material for solar-blind photodetection devices operating in the 200–280 nm interval. The crystal as a bandpass filter (280–615 nm) or a cut-off filter (615–1000 nm) are also excellent prospects for application.