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

Abstract

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°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 Cd 2+ were those assigned to 2E 2 (Low), E 2 (M), and 2B 1 (High), and this effect was associated with a greater displacement of Zn 2+ ions. The optical study showed a reduction in the band gap and a decrease in the crystalline quality due to the substitution of Cd 2+ 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.R. E. Riman-contributing editor Manuscript No. 35528.

Improved photoluminescence emission and gas sensor properties of ZnO thin films

“…The MR spectra of the ZnO thin films annealed under CF and PF conditions are presented in Fig. 4, showing five Raman active modes at 301, 430, 515, 623, and 928 cm À 1 , which can be assigned to the 3E 2h À E 2L , E 2(high) , A 1 (LO), and E 1 (LO) phonon modes respectively, and the local vibrational mode (LVM) mode located at 928 cm À 1 can be assigned to local vibrations on the Zn and O atoms in the crystalline structure, which are consistent with previous observations [52][53][54][55][56]. These results suggest that the CF and PF films are structurally ordered over the short-range.…”

“…where the A 1 , E 1 , and E 2 modes are Raman-active while the A 1 and E 1 modes are infrared-active. The B 1 modes are silent in the Raman and infrared spectra [50][51][52][53][54][55]. The MR spectra of the ZnO thin films annealed under CF and PF conditions are presented in Fig.…”

“…MR spectroscopy was employed to gain insight into the shortrange structural differences of the ZnO thin films (i.e., CF and PF). From group theory, the hexagonal wurtzite-type structure belongs to the space group P6 3 mc ( C v 6 4 ) with two formula units in the primitive unit cell (Z¼ 2) and has six optical modes, according to the irreducible representation: [51][52][53][54][55][56]…”

Structural, Optoelectronic, and Electrochemical Properties of Zn1–x(Ga0.5Al0.5)xO Nanoparticles for Supercapacitor Applications

“…Raman mode at around 329 cm –1 , (because of the combination of E 2 high  E 2 low ) is related to a multiphoton scattering process . A weak peak appears at ∼380 cm –1 corresponding to an A 1 (TO) vibration .…”

The Influence of Physical Properties of ZnO Films on the Efficiency of Planar ZnO/Perovskite/P3HT Solar Cell

“…Figure (a) shows the steady‐state PL spectrum of intrinsic ZnO film measured at room temperature with a 313 nm excitation light. For intrinsic ZnO sample, a sharp PL peak appears in the UV region centered around 380 nm, which is attributed to a near‐band‐edge recombination . For mixed halide perovskites CH 3 NH 3 PbI 3− x Cl x sample, we adopt 450 nm light from diode laser as the excitation source.…”