Nonlinear optical absorption and optical limiting properties of cadmium ferrite

Cadmium ferrite (CdFe₂O₄) was synthesized by simple combustion method and characterized by structural (XRD, SEM, EDS, and FTIR), magnetic (VSM) and nonlinear optical (Z-Scan) studies. Powder X-ray diffraction confirms the formation of cubic phase of CdFe₂O₄ with the cell constant a = 8.692 Å and a = 8.698 Å for the samples annealed at 500 °C and 800 °C respectively. The average crystallite size was found to increase with an increase in annealing temperature. In the IR spectra of spinel ferrites, the two major absorption bands ν₁ (553.47, 549.61 cm⁻¹) and ν₂ (410.75, 424.26 cm⁻¹) corresponds to the vibration of tetrahedral and octahedral sites of CdFe₂O₄. VSM studies shows that material is antiferromagnetic in nature, when heated at higher temperature. Optical nonlinearity of the samples was studied by open aperture Z-scan technique using Q-switched Nd:YAG (532 nm, 5 ns, 10 Hz) laser. The material possesses reverse saturable absorption and can be ascribed due to two photon absorption process. Also the materials exhibit optical limiting behavior with onset limiting value of 4.45 × 10¹² W/m², 3.59 × 10¹² W/m² for the samples annealed at 500 °C and 800 °C respectively. - Highlights: • Spinel cadmium ferrites were synthesized by combustion method. • As-synthesized sample show prominent hysteresis and heat treated show narrow hysteresis. • The observed nonlinearity arises due to two photon absorption behavior. • CdFe₂O₄ possesses lower limiting threshold due to the surface spin effect