Impact of Al3+ Ions Incorporation on the Enhancement of Optical and Electrical Properties of Cadmium Oxalate Crystals

Abstract

Aluminium (impurity ion) incorporated cadmium oxalate (ACO) crystals were grown in a silica hydrogel media by diffusion technique. ACO crystals emerged with the dimension 6´2´1.5 mm³ at the optimizing parameters of gel pH 4.2, gel density 1.01 g cm^-3, SMS: oxalic acid of 5:4 and supernatant mixture at an equal ratio (1:1). Further, the extracted crystals were analyzed by employing Energy dispersive X-ray analysis (EDAX), Fourier transform infrared (FTIR) spectroscopy and Thermogravimetric (TG) studies. EDAX measurements confirmed the presence of cations at the ratio Cd²⁺:Al³⁺= 65.67:1. FTIR spectra identified O-H, C-C, C-O, C=O and M-O bonds in the crystal armature. TG analysis showed two decomposition phases of foregrounded crystals with thermal stability up to 1076.79 ^oC in the metal oxide state with minimum change in entropy (∆S = -266.95 J mol^-1 K^-1). ACO crystal crystallized in a triclinic system. The optical and electrical behaviors of ACO crystals were compared with pure cadmium oxalate crystals. ACO crystals showed complete transparency to visible light and maximum absorption in the UV region like pure/parent crystals but the energy gap was reduced to 5.90 eV. The leakage resistance  of ACO crystals was also reduced to 6.583 GΩ and the electrical conductivity coefficient was enhanced to 0.152 S m^{-1 o}C^-1 from parent cadmium oxalate crystals.