Skip to main content Accessibility help

Plasmon-band subpeak and oxidation of solar-control LaB6 nanoparticles

  • Keisuke Machida (a1), Mika Okada (a2), Satoshi Yoshio (a3) and Kenji Adachi (a1)


Near-infrared (NIR) absorption in solar-control LaB6 nanoparticles (NPs) is derived from the localized surface plasmon resonance (LSPR) at 1.3 eV, and accompanies an unclarified subpeak at 1.8 eV. As an origin of this subpeak, a disk-like particle shape of LaB6 NP has recently been proposed, besides the previously-proposed, milling-derived LaO phase. A series of heating experiments at 200–850 °C in air for LaB6 NPs pulverized with different media beads have been made, followed by x-ray diffraction and transmission electron microscopy observations, to clarify that LaB6 NPs oxidizes to amorphous phases B2O3 and La–B–O at 450–600 °C, and crystallize to LaB3O6 at 650–750 °C, without forming LaO or La2O3. Dielectric functions of LaO have been derived by first-principles calculations using sX-LDA, and Mie scattering calculations have been made for various sizes, shapes, and the ensembles, showing that LaO NPs, if existed, should exhibit an excessively-broadened absorption band with a blunt LSPR peak at 2.1 eV buried in several interband-transition absorptions at 1.2–4.0 eV. These analyses confirm that the observed 1.8 eV subpeak could not originate from LaO and support the nonspherical shape of NPs as the origin of the subpeak.


Corresponding author

a) Address all correspondence to this author. e-mail:


Hide All
1. Trenary, M.: Surface science studies of metal hexaborides. Sci. Technol. Adv. Mater. 13, 023002 (2012).
2. Takeda, H., Kuno, H., and Adachi, K.: Film for cutting off heat-rays and a coating liquid for forming the same. US Patents 6060154, May 9, 2000; 6277187, August 21, 2001; and 6221945, April 24, 2001.
3. Takeda, H., Kuno, H., and Adachi, K.: Solar control dispersions and coatings with rare-earth hexaboride nanoparticles. J. Am. Ceram. Soc. 91, 2897 (2008).
4. Fisher, W.K.: Polyvinylbutyral blends with lanthanum hexaboride for use in laminated solar control glazing. In Proc. Glass Processing Days 2005, Tampere, June 17–20, 2005; p. 110.
5. Adachi, K., Miratsu, M., and Asahi, T.: Absorption and scattering of near-infrared light by dispersed lanthanum hexaboride nanoparticles for solar control filters. J. Mater. Res. 25(3), 510 (2010).
6. Yuan, Y.F., Zhang, L., Hu, L.J., Wang, W., and Min, G.H.: Size effect of added LaB6 particles on optical properties of LaB6/polymer composites. J. Solid State Chem. 184, 3364 (2011).
7. Jiang, F., Leong, Y.K., Saunders, M., Martyniuk, M., Faraone, L., Keating, A., and Dell, J.M.: Uniform dispersion of lanthanum hexaboride nanoparticles in a silica thin film: Synthesis and optical properties. ACS Appl. Mater. Interfaces 4(11), 5833 (2012).
8. Tang, H., Su, Y., Tan, J., Hu, T., Gong, J., and Xiao, L.: Optical properties and thermal stability of poly(vinyl butyral) thin films embedded with LaB6@SiO2 core-shell nanoparticles. Superlattices Microstruct. 75, 908 (2014).
9. Chen, C-J. and Chen, D-H.: Preparation of LaB6 nanoparticles as a novel and effective near-infrared photothermal conversion material. Chem. Eng. J. 180, 337 (2012).
10. Lai, B-H. and Chen, D-H.: LaB6 nanoparticles with carbon-doped silica coating for fluorescence imaging and near-IR photothermal therapy of cancer cells. Acta Biomater. 9(7), 7556 (2013).
11. Yoshio, S., Maki, K., and Adachi, K.: Optical properties of group-3 metal hexaboride nanoparticles by first-principles calculations. J. Chem. Phys. 144, 234702 (2016).
12. Kauer, E.: Optical and electrical properties of LaB6 . Phys. Lett. 7, 171 (1963).
13. Kimura, S., Nanba, T., Tomikawa, M., Kunii, S., and Kasuya, T.: Electronic structure of rare-earth hexaborides. Phys. Rev. B: Condens. Matter Mater. Phys. 46, 12196 (1992).
14. Kimura, S., Nanba, T., Kunii, S., and Kasuya, T.: Low-energy optical excitation in rare-earth hexaborides. Phys. Rev. B: Condens. Matter Mater. Phys. 50, 1406 (1994).
15. Leger, J.M., Aimonio, P., Loriers, J., Dordor, P., and Coqblin, B.: Transport properties of SmO. Phys. Lett. 80A, 325 (1980).
16. Machida, K. and Adachi, K.: Particle shape inhomogeneity and plasmon band broadening of solar-control LaB6 nanoparticles. J. Appl. Phys. 118, 013103 (2015).
17. Kresse, G. and Furthmüller, J.: Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 6, 15 (1996).
18. Kresse, G. and Furthmüller, J.: Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B: Condens. Matter Mater. Phys. 54, 11169 (1996).
19. Kresse, G. and Joubert, D.: From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B: Condens. Matter Mater. Phys. 59, 1758 (1999).
20. Perdew, J.P., Burke, K., and Ernzerhof, M.: Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865 (1996).
21. Bylander, D.M. and Kleinman, L.: Good semiconductor band gaps with a modified local-density approximation. Phys. Rev. B: Condens. Matter Mater. Phys. 41, 7868 (1990).
22. Seidl, A., Görling, A., Vogl, P., Majewski, J.A., and Levy, M.: Generalized Kohn-Sham schemes and the band-gap problem. Phys. Rev. B: Condens. Matter Mater. Phys. 53, 3764 (1996).
23. Bohren, C.F. and Huffman, D.R.: Absorption and Scattering of Light by Small Particles (Wiley Interscience, New York, 1983).
24. Ji, X.H., Zhang, Q.Y., Xu, J.Q., and Zhao, Y.M.: Rare-earth hexaborides nanostructures: Recent advances in materials, characterization and investigations of physical properties. Prog. Solid State Chem. 39, 51 (2011).
25. Mattox, T.M., Agrawal, A., and Milliron, D.J.: Low temperature synthesis and surface plasmon resonance of colloidal lanthanum hexaboride (LaB6) Nanocrystals. Chem. Mater. 27(19), 6620 (2015).
26. Samsonov, G.: Handbook of Refractory Compounds (Springer US, IFI/Plenum, New York, 1980).
27. Levin, E.M., Robbins, C.R., and Waring, J.L.: Immiscibility and the system lanthanum oxide-boric oxide. J. Am. Ceram. Soc. 44(2), 89 (1961).
28. Wen, C.H., Wu, T.M., and Wu, W.C.J.: Oxidation kinetics of LaB6 in oxygen rich conditions. J. Eur. Ceram. Soc. 24, 3235 (2004).
29. Sonber, J.K., Sairam, K., Murthy, T.S.R.Ch., Nagaraj, A., Subramanian, C., and Hubli, R.C.: Synthesis, densification and oxidation study of lanthanum hexaboride. J. Eur. Ceram. Soc. 34(5), 1155 (2014).
30. Leger, J.M., Yacoubi, N., and Loriers, J.: Synthesis of rare earth monoxides. J. Solid State Chem. 36, 261 (1981).


Related content

Powered by UNSILO

Plasmon-band subpeak and oxidation of solar-control LaB6 nanoparticles

  • Keisuke Machida (a1), Mika Okada (a2), Satoshi Yoshio (a3) and Kenji Adachi (a1)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.