Comprehensive analysis of a novel iron(III) bromide based organic-inorganic hybrid material: Structural, conduction mechanisms and magnetic properties studies

Abstract

A new organic–inorganic hybrid material, [(C 3 H 7 ) 4 N]FeBr 4 , was synthesized using the slow evaporation technique and thoroughly investigated. Its structural and physical properties were explored through single-crystal and powder X-ray diffraction, complex impedance spectroscopy, and magnetometry. Crystallographic analysis confirms that the compound adopts an orthorhombic structure, classified under the Pbca space group, with refined lattice parameters: a = 14.282 Å, b = 16.526 Å, and c = 17.662 Å. The crystal architecture features a layered configuration along the a -axis, consisting of alternating inorganic [FeBr 4 ] - anions and organic tetrapropylammonium ([(C 3 H 7 ) 4 N] + ) cations, arranged through electrostatic interactions. Impedance spectroscopy measurements reveal a strong dependence of the electrical response on both frequency and temperature, indicative of a relaxation mechanism driven by thermal activation. The observed negative temperature coefficient of resistance (NTCR) behavior confirms the semiconducting character of the material, with an activation energy of about 0.36 eV in the 303–363 K range. The AC conductivity behavior aligns with Jonscher’s power law, supporting a hopping conduction model. Moreover, the variation of the power law exponent with temperature points to a correlated barrier hopping (CBH) mechanism, with a calculated maximum barrier energy (W M ) of 0.20 eV. Magnetic investigations show clear evidence of antiferromagnetic interactions among Fe 3+ ions.