Structural, opto-electronic, magnetic and photoluminescence properties of samarium and gadolinium iron garnet nanomaterials for LED and opto-electronics applications

Samarium Iron Garnet (SIG) and Gadolinium Iron Garnet (GIG) functional materials, were synthesized by low-cost chemical-based sol-gel method. XRD study found crystal structure of sizes ranging between 36 nm and 48 nm for GIG and between 35 nm and 65 nm for SIG. Photoluminescence property shows that both materials exhibit intense blue light emission when excited by 200 nm radiation in the visible region. The energy band gap was found to be 1.36 eV to 1.44 eV respectively at 700 °C and 900 °C for SIG nanomaterials, whereas the band gap for GIG nanomaterials was found to be in the range of 1.425 eV to 1.375 eV respectively at 700 °C and 900 °C which is in the range of GaAs have been used in LED applications. These result shows that the band gap is a function of crystallite size and can be used in Light emitting diodes application under controlled specific annealing temperature. The magnetic behavior of SIG nanomaterial shows that Coercivity and magnetization decreases but retentivity increases with the increase of annealing temperature (from 700oC to 900oC).The magnetization curve found like S-like structure. Whereas for GIG nanomaterials, magnetization and retentivity decreases but coercivity increases with the increase of annealing temperature from 700oC to 900oC. The coercivity and saturation magnetization (118.72 Oe and 0.685 emu/gm) value of the prepared materials is very low showing soft magnetic behavior. This property may be useful for its application in development of electrical devices such as transformer cores (for sufficient energy transfer) and microwave devices (for signal processing, Inductors (to store magnetic energy and read-write heads in the magnetic storage.