Photoacoustic spectroscopy of Ln3+ (Nd, Ho, and Er) doped ThO2

Undoped and ThO2:Ln3+ (Ln = Nd, Ho, and Er) were synthesized by wet chemical route and characterized using X-ray diffraction (XRD). PAS was used to investigate electronic absorption of Nd3+, Ho3+ and Er3+ in thorium dioxide as well as of pure rare earth oxide powder Ln2O3 (Ln = Nd, Ho, and Er). PA spectra were also obtained for aqueous solution of lanthanides for evaluating various covalency parameters. Various covalency parameters like nephelauxetic ratio (β), covalency factor (b1/2) and Sinha parameter (δ) were evaluated for pure oxide powder and for rare earth doped thoria for all these system from their individual PA spectra.