Photon Upconversion, Structural, And Magnetic Properties Of Rare Earth-doped Nayf4 Nanoparticles

Magnetic, structural, and optical investigations of rare-earths (R) co-doped nanoparticles (NPs) of Nay1-x-yRx 1Ry 2F4 with Rx 1. = Yb0.20/Ry 2 = Er0.02 and R.J. = Yb0.30/Ry 2 = Tm0.005 and single doped (y = 0) with Rx 1. = Yb0.20 and Rx1. = Er0.02 are reported. The visible green and blue upconversion emitted lights of Yb/Er and Yb/Tm co-doped NaYF4 NPs were observed with naked eye and no filters when excited with a 980 nm laser diode. The NPs are mixture of both phases, α (cubic nanospheres: 15-25 nm) and β (hexagonal nanoplates: ~230 nm). From the observed electron spin resonance (ESR) signals and Curie-Weiss fits of the temperature dependence of the magnetization, we obtained the oxidation states to be trivalent ions, i.e., Yb3+ (4f13, J = 7/2) and Er3+ (4f11, J = 15/2). As expected for NPs with mixture of α- and β-phases, the ESR spectra broaden toward higher magnetic fields due to the anisotropic contribution of the crystal electric field to the Kramer ground state g-values.15962BASF - The Chemical Company,Boeing,K and L Gates,Thermo Scientific,Intellectual Property Insurance Services Corporation (IPISC),ChiNanoScheps, R., (1996) Prog. Quant. Electron., 20, p. 271Cohen, B.E., (2010) Nature, 467, p. 407Auzel, F., (2004) Cliera. Rev., 104, pp. 139-173Suyver, J.F., Aebischer, A., Biner, D., Cerner, P., Grimm, J., Heer, S., Kramer, K.W., Güdel, H.U., (2005) Optical Materials, 27, p. 1111Wang, F., Liu, X., (2009) Chem. Soc. Rev., 38, p. 976Krämer, K., Biner, D., Frei, G., Gwdel, H., Hehlen, M., Lüthi, S., (2004) Chem. Mater., 16, pp. 12441-251Wang, F., Liu, X.G., (2008) J. Am. Chem. Soc., 130, p. 5642Chen, G., Ohulchanskyy, T.Y., Kumar, R., Agren, H., Prasad, P.N., (2010) ACS Nano, 1, p. 3163Suyver, J.F., Grimm, J., Van Veen, M.K., Biner, D., Krämer, K.W., Güdel, H.U., (2006) Journal of Luminescence, 117, pp. 1-12Ye, X., Collins, J.E., Kang, Y., Chen, J., Chen, D.T.N., Yodh, A.G., Murray, C.B., (2010) Proceeding of the National Academy of Science of the United States of America, 107, p. 22430Gao, D., Zhang, X., Gao, W., (2012) J. Appl. Phys., 111, p. 033505Wang, G., Peng, Q., Li, Y., (2011) Accounts of Chemical Research, 44, p. 322Wang, Y.-F., Sun, L.-D., Xiao, J.-W., Feng, W., Zhou, J.-C., Shen, J., Yan, C.-H., (2012) Chem. Eur. J., 18, p. 5558Boyer, J.-C., Vetrone, F., Cuccia, L.A., Capobianco, J.A., (2006) J. Am. Chem. Soc., 128, p. 7441. , J.-CMai, H.-X., Zhang, Y.-W., Si, R., Yan, Z.-G., Sun, L.-D., You, L.-P., Yan, C.-H., (2006) J. Am. Chem. Soc., 128, p. 6426Roberts, J.E., (1961) J. Am. Chem. Soc., 83, p. 1087Schietinger, S., Menezes, L., Lauritzen, B., Benson, O., (2009) Nano Lett., 9, p.