Role of Synthesis Method on Luminescence Properties of Europium(II, III) Ions in β‑Ca₂SiO₄: Probing Local Site and Structure

The europium ion probes the symmetry disorder in the crystal structure, although the distortion due to charge compensation in the case of aliovalent dopant remains interesting, especially preparation involves low and high temperatures. This work studies the preparation of the β-Ca₂SiO₄ (from here on C₂S) particle from Pechini (C₂SP) and hydrothermal (C₂SH) methods, and its luminescence variance upon doping with Eu²⁺ and Eu³⁺ ions. The blue shift of the charge-transfer band (CTB) in the excitation spectra indicates a larger Eu³⁺–O^2– distance in Eu³⁺ doped C₂SH. The changes in vibrational frequencies due to stretching and bending vibrations in the FTIR and the Raman spectra and binding energy shift in the XPS analysis confirmed the distorted SiO₄^4– tetrahedra in C₂SH. The high hydrothermal temperature and pressure produce distortion, which leads to symmetry lowering although doping of aliovalent ion may slightly change the position of the Ca atoms. The increasing asymmetry ratio value from C₂SP to C₂SH clearly indicates that the europium ion stabilized in a more distorted geometry. It is also supported by Judd–Ofelt analysis. The concentration quenching and site-occupancy of Eu³⁺ ions in two nonequivalent sites of C₂S were discussed. The charge state and concentration of europium ions in C₂SP and C₂SH were determined using X-ray photoelectron spectroscopy measurements. The C₂S particles were studied by X-ray powder diffraction, FTIR, Raman, BET surface area, TGA/DTA, electron microscopy, XPS, and luminescence spectroscopy. The impact of citrate ion on the morphology and particle size of C₂SH has been hypothesized on the basis of the microscopy images. This study provides insights that are needed for further understanding the structure of C₂S and thereby improves the applications in optical and biomedical areas and cement hydration

Preparation and Optical Properties of Nd:Bi₂Ti₂O₇ Laser Crystal with Disordered Structure and Attractive Multiwavelength Emission Characteristics

Laser crystals with multiwavelength emission characteristics are potential light sources for terahertz radiation. Herein, the pure and Nd-doped Bi2Ti2O7 (BTO) laser crystals with sizes up to 16 × 13 × 5 mm3 were successfully grown using the flux method in the KF-B2O3–CaBi4Ti4O15 growth system. The crystal structure, ideal morphology, chemical, mechanical, and thermal properties, optical transmission and Raman spectra, refractive index, absorption, and fluorescence spectra, as well as fluorescence lifetimes, were systematically studied. Besides, the spectral parameters of Nd3+ ions in the BTO crystal were systematically calculated based on the Judd–Ofelt theory. The Nd:BTO crystal has a wide transmittance range (0.44–7.30 μm), a small coefficient of thermal expansion (5.80 × 10–6 K–1), and a large absorption full width at half-maximum (fwhm) (31.2 nm) at around ∼804 nm, making it more potential for use in high-power laser systems. Moreover, fluorescence spectra show four emission peaks at 1054, 1062, 1104, and 1112 nm. The strong multiwavelength emission property makes Nd:BTO a promising laser crystal, serving as a potential light source for terahertz radiation

Preparation and Optical Properties of Nd:Bi₂Ti₂O₇ Laser Crystal with Disordered Structure and Attractive Multiwavelength Emission Characteristics

Laser crystals with multiwavelength emission characteristics are potential light sources for terahertz radiation. Herein, the pure and Nd-doped Bi2Ti2O7 (BTO) laser crystals with sizes up to 16 × 13 × 5 mm3 were successfully grown using the flux method in the KF-B2O3–CaBi4Ti4O15 growth system. The crystal structure, ideal morphology, chemical, mechanical, and thermal properties, optical transmission and Raman spectra, refractive index, absorption, and fluorescence spectra, as well as fluorescence lifetimes, were systematically studied. Besides, the spectral parameters of Nd3+ ions in the BTO crystal were systematically calculated based on the Judd–Ofelt theory. The Nd:BTO crystal has a wide transmittance range (0.44–7.30 μm), a small coefficient of thermal expansion (5.80 × 10–6 K–1), and a large absorption full width at half-maximum (fwhm) (31.2 nm) at around ∼804 nm, making it more potential for use in high-power laser systems. Moreover, fluorescence spectra show four emission peaks at 1054, 1062, 1104, and 1112 nm. The strong multiwavelength emission property makes Nd:BTO a promising laser crystal, serving as a potential light source for terahertz radiation

Legislative Documents

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Different views of the casting mold sherd.

<p>(A-F) Six faces of the casting mold sherd.</p

EDS results of the elemental analysis of the casting mold sherd.

<p>EDS results of the elemental analysis of the casting mold sherd.</p

Map of the Shang Dynasty and location of Daxinzhuang.

<p>Both Yin Ruins and Daxinzhuang sites are marked in the map. Reprinted from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0174057#pone.0174057.ref011" target="_blank">11</a>] under a CC BY license, with permission from [Lamassu Design], original copyright [2009].</p

AMS-¹⁴C dating of archaeological pig bone.

<p>AMS-¹⁴C dating of archaeological pig bone.</p

X-ray fluorescence mapping of copper and iron mapping in front decoration and back groove.

<p>(A) A groove is labelled by a white rectangle on the back of the casting mold sherd. One red dashed line indicates the deepest position in the groove. (B) X-ray fluorescence mapping of the copper on the back and a white dashed line encircles the groove. (C) X-ray fluorescence mapping of the iron on the back and a black dashed line encircles the groove. One side of the deepest line shows a gathering of iron, and on the other side, this reverses. (D) A probing range is labelled by a white rectangle on the front of the casting mold sherd. (E), (F) X-ray fluorescence mapping on the front decoration of copper and iron, respectively. Both elements have an uneven distribution and some correspondence to the profile of decorated patterns.</p