Associated Aspects on Structure, Morphology and Photoluminescence of MgAl2O4:x% Gd3+ Nanophosphor Prepared via Citrate Sol–Gel Method

Abstract

MgAl2O4:x% Gd 3+ (0 ≤ x ≤ 3) nano-powders were prepared via citrate sol-gel method. The X-ray diffraction (XRD) confirmed that the prepared samples consists of the cubic crystalline structures. There was no secondary phases due to Gd 3+ doping. The estimated average grain sizes were found to be in the order of 8 nm. Energy dispersive spectroscopy (EDS) showed the presence of the anticipated elements (Mg, Al, O, and Gd). The scanning electron microscope (SEM) results revealed that the morphology of the samples is influenced by the Gd 3+ concentration. Transmission electron microscopy (TEM) analysis revealed that the prepared samples are in the nano-scale range. Selected area electron diffraction (SAED) patterns indicated highly crystalline structure and the intensities of the bright spots varied with Gd 3+ concentration. Photoluminescence (PL) studies showed two distinct emission peaks at 385 and 392 nm, which are certainly attributed to the defects levels located at different positions on the host material (MgAl2O4). The emission peaks located at 315 and 628 nm were respectively attributed to the 6 P7/2→ 8 S7/2 and 6 G7/2→ 6 P3/2 transitions in Gd 3+ ion. The luminescence intensity of the 388 nm decreased with an increase in the Gd 3+ concentration. Commision Internationale de l'Eclairage (CIE) coordinates showed that the violet emission color from host cannot be tuned by varying Gd 3+ concentration.

Surface and Optical Properties of Gd-Doped ZrO2 Nano Films

“…This type of radiation is known to be effective for treating skin diseases such as vitiligo vulgaris, psoriasis, and periodontitis [13][14][15][16][17][18]. The red emission peak at 628 nm can be attributed to the 6 G7/2 → 6 P3/2 transition as the excitation energy of 5.39 eV should be enough for the excited electron to reach the conduction band of the host material where the 6 Gj energy state of Gd 3+ is located [19]. The overall emission colour of our thin films is pinpointed on the CIE chromaticity diagram shown in Figure 5a.…”