Page 118 - Synthesis of Functional Nanoparticles Using an Atmospheric Pressure Microplasma Process - LiangLiang Lin

Chapter 6
rougher morphology. The high magnification image shows the existence of well-dispersed spheres that are aggregated by irregular particles with clear grain fringes. The morphology difference of the Y(OH)3 and Y2O3 products is probably due to the heat-treatment, in which hydroxide powders experience a dehydration process, leading to smaller and rougher fragments.
In addition, EDX mapping of the Y2O3 products was also carried out (Supplementary Material Figure S3). The elemental mapping revealed that Y and O have a rather uniform spatial distribution. The overall EDX spectrum shows the expected presence of Y, O and minor C (probably from the sample holding carbon tape), without the indication of any impurities in the products.
Figure 6.3 SEM images of the (a-b) synthesized Y(OH)3 and (c-d) Y2O3 annealed at 600 °C
Figure 6.4 shows the FTIR spectra of the dried Y(OH)3 powders and Y2O3 nanoparticles obtained at calcination temperature of 600 °C. The detailed information of the absorptions bands is summarized in Table 1. The spectrum of Y(OH)3 shows a broad band at 3602 cm-1, which is due to the O-H stretching vibration. Meanwhile, the weak band at 1664 cm-1 is attributed to the O-H deformation vibration.9 The bands at 1510 cm-1, 1411 cm-1 and 1052 cm-1 are assigned to different vibrations of carboxylate group, which may originate from CO2 absorption when exposed to air; same phenomena have also been reported by Mustafa,9 Lakshminarasappa 5 and Giang. 23 Peaks at 819 cm-1 and 603 cm-1 are related to the Y-OH stretching mode.22 The spectrum of Y2O3 reveals that the intensity of OH and carbonate groups decrease significantly. By contrast, new absorption bands corresponding to the Y-O stretching mode appear at 599 cm-1, 555 cm-1 and 464 cm-1, indicating the formation of Y2O3 nanoparticles from Y(OH)3.6,22
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