Effect of nano-sized cerium–zirconium oxide solid solution on far-infrared emission properties of tourmaline powders

Abstract

Far-infrared functional nanocomposites were prepared by the co-precipitation method using natural tourmaline [Formula: see text], where [Formula: see text] is [Formula: see text], [Formula: see text], [Formula: see text], or vacancy; [Formula: see text] is [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], or [Formula: see text]; [Formula: see text] is [Formula: see text], [Formula: see text], [Formula: see text], or [Formula: see text]; [Formula: see text] is [Formula: see text], [Formula: see text]; and [Formula: see text] is [Formula: see text], [Formula: see text], or [Formula: see text] powders, ammonium cerium(IV) nitrate and zirconium(IV) nitrate pentahydrate as raw materials. The reference sample, tourmaline modified with ammonium cerium(IV) nitrate alone was also prepared by a similar precipitation route. The results of Fourier transform infrared spectroscopy show that tourmaline modified with Ce and Zr has a better far-infrared emission property than tourmaline modified with Ce alone. Through characterization by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), the mechanism for oxygen evolution during the heat process in the two composite materials was systematically studied. The XPS spectra show that [Formula: see text] ratio inside tourmaline modified with Ce alone can be raised by doping Zr. Moreover, it is showed that there is a higher [Formula: see text] ratio inside the tourmaline modified with Ce and Zr than tourmaline modified with Ce alone. In addition, XRD results indicate the formation of [Formula: see text] and [Formula: see text] crystallites during the heat treatment and further TEM observations show they exist as nanoparticles on the surface of tourmaline powders. Based on these results, we attribute the improved far-infrared emission properties of Ce–Zr doped tourmaline to the enhanced unit cell shrinkage of the tourmaline arisen from much more oxidation of [Formula: see text] to [Formula: see text] inside the tourmaline caused by the change in the catalyst redox properties of [Formula: see text] brought about by doping with [Formula: see text]. In all samples, tourmaline modified with 7.14 wt.% Ce and 1.86 wt.% Zr calcined at 800[Formula: see text]C for 5 h has the best far-infrared emission property with the maximum emissivity value of 98%.