Spectral and nonlinear optical transmission studies of Zr4+-doped TiO2 nanoparticles

Zr4+-doped TiO2 nanoparticles with a homogeneous anatase structure were synthesized through sol–gel technique. The crystalline phase and particle sizes of the resultant particles were investigated by X-ray diffraction (XRD), Raman and transmission electron microscopy (TEM) techniques. Results indicated that Zr4+ was incorporated into the lattice and interstices of titania nanocrystals. The amount of Zr4+ doping decreased the size of particle, and enhanced “blue-shift” in the UV–vis absorption spectra. The optical limiting property of the samples was assessed by a Z-scan technique in which the Zr4+/TiO2 nanoparticles dispersed in ethylene glycol were excited at 532 nm using 7 ns Nd:YAG laser pulses. Experimental results indicated that at 0.5 and 1.0 mol% doping of Zr4+ the particles exhibit three-photon absorption while for at 2.0 and 3.0 mol% dopant concentration the data fitted to saturable absorption followed by two-photon absorption.