Copper Nanoparticles Embedded in Natural Plagioclase Mineral Crystals: In Situ Formation and Third-Order Nonlinearity

Copper nanoparticles are low-cost plasmonic materials with the ability of manipulating light at the nanometer scale. The exploration of copper nanoparticles toward photonic applications suffers instability due to the easy prone oxidation. In this paper, we developed the in situ formation of copper nanoparticles with a diameter between 40 and 50 nm in a natural plagioclase mineral crystal matrix by controlling the Cu+-Na+ ion exchange process in the temperature range of 1050-1200 degrees C. By combining quantitative element distribution characterization and spectroscopic measurement, we illustrate the in situ formation process and mechanism of Cu nanoparticles in natural plagioclase mineral crystals. Moreover, we determined the nonlinear optical properties of the materials by using the picosecond Z-scan technique. The third-order nonlinear optical susceptibility chi((3)) at 1064 and 532 nm was estimated to be (1.046 +/- 0.213) x 10(-10) esu and (3.236 +/- 0.198) x 10(-10) esu, respectively. The natural plagioclase mineral crystals embedded with copper nanoparticles are believed to hold great potential to serve as plasmonic materials for a variety of practical applications, especially in nonlinear optics.