Optical properties of group-3 metal hexaboride nanoparticles by first-principles calculations

Abstract

LaB6 nanoparticles are widely used as solar control materials for strong near-infrared absorption and high visible transparency. In order to elucidate the origin of this unique optical property, first-principles calculations have been made for the energy-band structure and dielectric functions of R(III)B6 (R(III) = Sc, Y, La, Ac). On account of the precise assessment of the energy eigenvalues of vacant states in conduction band by employing the screened exchange method, as well as to the incorporation of the Drude term, dielectric functions and various physical properties of LaB6 have been reproduced in excellent agreement with experimental values. Systematic examinations of dielectric functions and electronic structures of the trivalent metal hexaborides have clarified the origin of the visible transparency and the near-infrared plasmon absorption of R(III)B6 nanoparticles.

First-Principles Calculations of x-Dependent Ground Structures and Optical Properties of CaxLa1–xB6

“…In terms of ε 2 (ω), LaB 6 absorbs weakly in the visible light region, and a high absorption is observed in the low-energy side including the near-infrared region. These characteristics are consistent with the measurements 3,8,10 and calculated values 18 reported in previous studies. For applications as a solar shielding material, ε 2 (ω) should have a large value in the near-infrared region and a small value in the visible region.…”

“…The crystal structure of LaB 6 is shown in Figure 1 A previous study reported by our research group shows that the optical characteristics of LaB 6 can be reproduced quantitatively by considering the Drude term, which includes the effect of free electrons, and by calculating the effect of interband transitions using a hybrid calculation method that accurately reproduces the band gap. 18 Details are described in the Methods section.…”

“…It has been previously reported by our research group that the dielectric functions that determine the optical properties of LaB 6 can be predicted with high accuracy by first-principles calculations. 18 The optical properties of nanoparticle dispersions are analyzed by the dielectric functions and Mie scattering theory, but when the particle shape and dielectric functions are modulated during the nanoparticle formation, as in the case of LaB 6 , 12,19 a new analysis method such as the Mie scattering integration (MSI) method is used to describe the optical response. The MSI method integrates the individual Mie scattering waves from particles with inhomogeneous physical properties and/or shapes in an ensemble.…”

Cesium polytungstates with blue-tint-tunable near-infrared absorption

“…This prohibition of certain transitions between metal-d and ligand-p orbitals further amplies the visible transparency, enabling it even when the conduction and valence bands overlap in specic directions, as occurs in LaB 6 . 21 The optical absorption of Cs-HTB nanoparticles is known large at both frequency ends of the visible region. On the blue side of the spectrum, the 3 2 is enlarged by band-edge interband transition; on the red side, strong absorption occurs by LSPR and polaronic electronic transition.…”

Synthesis of LaBe-ZrBz powder mixture by borothermal reduction of La(OHh and ZrO(OH)2 co-precipitated in a boron suspension

“…Ключевые слова: совместное осаждение, боротермическое восстановление, гексаборид лантана, диборид циркония. ВВЕДЕНИЕ Э втектические композиции в системах LnB 6 -MeB 2 (где Ln -лантаноиды, Me -переходные металлы IV-VI групп) обладают высоким уровнем термоэмиссионных [1-8] и физикомеханических свойств [6,[9][10][11][12][13][14], а также представляют потенциальный интерес вследствие выдающихся оптических характеристик гексаборидов РЗМ в ближней ИК-области спектра [15][16][17][18][19]. Благодаря высокой температуре плавления и способности в процессе окисления поверхностного слоя образовывать стабильные цирконаты и гафнаты со структурой пирохлора LaB 6 применяется в качестве добавок к ZrB 2 и HfB 2 при создании ультравысокотемпературных керамик (UHTCs), в частности в составе квазитройной системы ZrB 2 -SiC-LaB 6 [20].…”