Absorption peak decomposition of an inhomogeneous nanoparticle ensemble of hexagonal tungsten bronzes using the reduced Mie scattering integration method.

Recent optical analyses of cesium-doped hexagonal tungsten bronze have accurately replicated the absorption peak and identified both plasmonic and polaronic absorptions in the near-infrared region, which have been exploited in various technological applications. However, the absorption peaks of tungsten oxides and bronzes have not generally been reproduced well, including those of the homologous potassium- and rubidium-doped hexagonal tungsten bronzes that lacked evidence of polaronic subpeaks. The present study reports a modified and simplified Mie scattering integration method which incorporates the ensemble inhomogeneity effect and allows precise peak decomposition and determination of the physical parameters of nanoparticles.

Rational Cationic Disorder in Hexagonal Cesium Tungsten Bronze Nanoparticles for Infrared Absorption Materials.

Hexagonal cesium tungsten bronze (CsWO) nanoparticles (NPs) have attracted attention for their potential applications in near-infrared (NIR) absorbing materials. However, the insufficient Cs doping in CsWO NPs has limited their NIR absorbing capabilities and practical stability. In this study, we demonstrate the transition pathway from intermediate W-defective CsWO NPs synthesized by flame spray pyrolysis to cationic (Cs, W)-disordered CsWO NPs prepared through appropriate heat treatments.

Gigantic Thermal Shielding in 2D Oxide Nanosheets.

Thermal shielding materials that can block near-infrared (NIR) light from the sunlight while maintaining visible transparency have become increasingly important from an energy-saving perspective. Here, we demonstrate a gigantic NIR shielding by an engineered plasmonic material based on a two-dimensional (2D) polytungstate (CsWO). Starting from a charge-neutral polytungstate (CsWO), we synthesize charge-imbalanced 2D nanosheets (CsWO) that undergo an unusual structural change with the semiconductor-to-metal transition in a reduced atmosphere.

LaTiON nanopowders (NPs) with low surface defect density nitridation of flame made NPs retaining simple perovskite structure.

This work introduces a novel route to perovskite LaTiON nanopowders (NPs) nitridation of perovskite LaTiO NPs in an NH gas flow at 1050 °C/NH/15 h, in which a simple perovskite structure (ABX) is retained during nitridation. The LaTiO NP is formed with a trace of a second phase in a precursor oxide NP (LTO-4/3) produced using liquid-feed flame spray pyrolysis (LF-FSP) of a metallo-organic ethanol solution with La/Ti = 4/3. The characterization of the resulting powders allows for a comparison with LaTiON NPs synthesized by the nitridation of the LaTiO precursor oxide NP (LTO-1) with a perovskite slab structure (ABX) also prepared by LF-FSP of a La/Ti = 1 solution.

Electron transfer in LiMn1.5Ni0.5O4 during charging studied with soft X-ray spectrometry.

This is the first report on analyzing the chemical state of Li-ion battery electrodes at different states of charge by using a wavelength-dispersive spectrometer, which has a two-order improved energy resolution in the soft X-ray energy region compared with that of a conventional energy-dispersive X-ray analyzer. Electrodes containing LiMn1.5Ni0.

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

Revisiting Wöhler's method (1824), Cs-doped tungsten bronzes were synthesized by reducing Cs-polytungstate at high temperature, and were pulverized into nanoparticles for determining their optical properties. The high-temperature reduced CsWO crystals absorbed strongly in the near-infrared, providing an improved luminous transparency with a less-bluish tint than normal CsWO synthesized in a reductive atmosphere. The high-temperature reduction caused an orthorhombic-to-hexagonal phase transformation and a nonmetal-metal transition, which was monitored by spectrophotometry, X-ray diffraction, and X-ray photoelectron spectroscopy measurements, assisted by a first-principles analysis using a DFT+U method.

First-Principles Calculations of -Dependent Ground Structures and Optical Properties of Ca La B.

High transparency in the visible region is desired to manufacture solar control films and glasses for various applications. To improve the visible light transparency of LaB nanoparticles which exhibit strong absorption in the near-infrared region, the substitution of La with Ca is investigated using first-principles calculations. Among the numerous atomic replacement configurations in Ca La B, all 762 structures existing in the supercells that are up to 8 times the primitive cell are comprehensively evaluated, and the most stable ground structures in Ca La B are deduced.

Cationic Defect Engineering for Controlling the Infrared Absorption of Hexagonal Cesium Tungsten Bronze Nanoparticles.

Cesium tungsten bronzes (CsWO) have attracted much attention as a near-infrared absorbing material. We report the successful synthesis of highly crystalline and high purity CsWO nanoparticles through a spray pyrolysis route. Careful analyses disclosed the presence of cationic defects, that is, a tungsten deficiency and insufficient Cs doping in the CsWO nanoparticles.

Direct observation of Mn and Ni ordering in LiMn1.5Ni0.5O4 using atomic resolution scanning transmission electron microscopy.

LiMn1.5Ni0.5O4 is an excellent candidate as a cathode-active material in high-voltage lithium-ion batteries and studied using atomic resolution scanning transmission electron microscope.

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

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.