Optical and Structural Properties of ZnO and ZnO:Cd Particles Grown by the Hydrothermal Method

Here, we examine the structural, vibrational, optical, and morphological properties of ZnO particles synthesized by the hydrothermal method, incorporating cadmium at different concentrations through the molar ratio R-m = Cd+2/Zn+2 and a thermal treatment at 500 degrees C. The X-ray diffraction results demonstrated the high crystallinity of the ZnO compound with a wurtzite-type hexagonal structure. The Raman scattering spectra demonstrated that the ZnO vibrational modes occur in the region between 200 and 1300 cm(-1), which is associated with different vibrational configurations characteristic of the ZnO molecule: E-2(Low), E-2(M), A(1)(TO) E-1(TO), 2B(1)(High), E-2(High), and TA + LO. The modes that were most affected by the incorporation of Cd2+ were those assigned to 2E(2)(Low), E-2(M), and 2B(1)(High), and this effect was associated with a greater displacement of Zn2+ ions. The optical study showed a reduction in the band gap and a decrease in the crystalline quality due to the substitution of Cd2+ in the ZnO lattice. Cadmium incorporation affected the morphology of the ZnO:Cd particles, changing the lengths and diameters of the ZnO rods; when the Cd concentration was increased, the ZnO rods shortened, forming coin-type hexagonal structures.