Media type: E-Article Title: Cation Exchange: A Facile Method To Make NaYF4:Yb,Tm-NaGdF4 Core–Shell Nanoparticles with a Thin, Tunable, and Uniform Shell Contributor: Dong, Cunhai; Korinek, Andreas; Blasiak, Barbara; Tomanek, Boguslaw; van Veggel, Frank C. J. M. imprint: American Chemical Society (ACS), 2012 Published in: Chemistry of Materials Language: English DOI: 10.1021/cm2036844 ISSN: 0897-4756; 1520-5002 Origination: Footnote: