Synthesis and optical limiting effects in ZrO2 and ZrO2@SiO2 core–shell nanostructures

ZrO2 nanoparticles were synthesized by the chemical precipitation method and coated with silica through seeded polymerization technique to form core–shell type ZrO2@SiO2 nanostructures. The structural, morphological and silica coating formation of the bare and silica coated particles were studied using Transmission electron microscopy, X-ray diffraction and Fourier Transform Infrared Spectroscopy. Thermogravimetric analysis and Zeta potential measurements were performed to check the thermal and dispersion stability of the nanostructures. The optical limiting performance of these nanostructures was studied using open-aperture Z-scan technique in which nanosecond laser pulses at 532 nm have been used for optical excitation. Both bare and silica coated ZrO2 nanoparticles exhibited good optical limiting behavior due to excited state absorption, arising from effective three photon absorption. It is observed that the optical nonlinearity is enhanced in core shell structures as compared with the bare particles.