The crystalline structure of gadolinium oxide nanoparticles (Gd2O3-NPs) synthesized at different temperatures via X-ray diffraction (XRD) technique

Sol-gel is an effective method in producing nanoparticles with high purity and crystallinity. Herein, we report the synthesis of gadolinium oxide nanoparticles (Gd2O3-NPs) via sol-gel technique with an emphasis on the effect of temperature on the crystallization process of the nanoparticles. Gd2O3-NPs were prepared from gadolinium chloride hexahydrate precursor (GdCL(3 center dot)6H(2)O) and ethylene glycol (EG). The Gd2O3-NPs were synthesized at different annealing temperatures of 500 degrees C, 700 degrees C, 900 degrees C, 1000 degrees C and 1100 degrees C. The X-ray diffraction (XRD) analysis revealed that the sample was crystalline with a cubic phase, achieving optimum crystallinity (82.3%) at an annealing temperature of 1000 degrees C. The Williamson-Hall (W-H) analysis and size-strain plot (SSP) method demonstrated that the strain decreases with the increment of particle size. Whereby the strain and average particle size of Gd2O3-NPs synthesized at the temperature of 1000 degrees C were 0.00053 and 62.96 nm respectively. Further investigation by transmission electron microscopy (TEM) indicated that the Gd2O3-NPs is a single-crystal with approximately polycrystalline shapes. The particle size ranges from 38.01 +/- 5.9 nm, 49.29 +/- 7.41 nm, 60.58 +/- 6.7 nm and 74.34 +/- 9.3 nm per annealing temperature of 700 degrees C, 900 degrees C, 1000 degrees C and 1100 degrees C respectively. Whereas, via field emission scanning electron microscopy (FESEM), synthesized Gd2O3-NPs were uniform and had spherical-like morphology with an average diameter of 40.71 +/- 4.5 nm, 52.92 +/- 6.9 nm, 65.00 +/- 7.02 nm and 73.56 +/- 10.04 nm at different annealing temperatures of 700 degrees C, 900 degrees C, 1000 degrees C and 1100 degrees C respectively. The results obtained showed that the mean particle size of the Gd2O3-NPs estimated from the TEM, FESEM, W-H analysis and SSP method were inter-correlated. In terms of molecular conformation, Fourier transform infrared spectroscopy (FTIR) peaks at 448 cm(-1) and 546 cm(-1) affirms the formation of the Gd2O3-NPs, whereby these peaks corresponds to the Gd-0 stretching frequencies of Gd2O3 cubic phase when samples were heated at 700 degrees C - 1100 C. It is envisaged that the sol-gel technique is promising in synthesizing Gd2O3-NPs for various possible applications, potentially as a contrast agent for magnetic resonance imaging (MRI).

Automated summary

The Sol-gel technique is an effective method for producing high purity and crystalline nanoparticles, as demonstrated in the synthesis of gadolinium oxide nanoparticles (Gd2O3-NPs) with varying annealing temperatures. The particles showed optimal crystallinity at 1000 degrees C, with uniform spherical morphology observed through TEM and FESEM imaging. FTIR analysis confirmed the formation of Gd2O3-NPs, indicating potential applications as a contrast agent for MRI.