The structural disorder of a silica network probed by site selective luminescence of the nonbridging oxygen hole centre

In this paper, defect induced by heated treatment in silica is studied. The formation process of defect is analyzed by the thermodynamic model. The results show that defect can be produced by thermal treatment process. The concentration of defect can be affected by many factors. The defect formation induced by heated treatment is related to the initial precursors. To pure silica glass, the precursors mainly come from the strained bonds of network. It can produce centers and nonbridging oxygen hole centers (NBOHCs). These defects are also related to the temperature of heated treatment and the conversion frequency between precursors and defects. The changes of defect concentration with temperature and conversion frequency are also discussed in detail.

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Luminescence properties of nonbridging oxygen hole centers at the silica surface

Journal of Non-Crystalline Solids ◽

10.1016/j.jnoncrysol.2008.11.028 ◽

2009 ◽

Vol 355 (18-21) ◽

pp. 1020-1023 ◽

Cited By ~ 23

Author(s):

L. Vaccaro ◽

M. Cannas ◽

V. Radzig

Keyword(s):

Silica Surface ◽

Luminescence Properties ◽

Nonbridging Oxygen ◽

Oxygen Hole ◽

Hole Centers

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Site-selective analyses of battery reactivities in Li1+xNi1-xO2by powder DAFS

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s205327331409411x ◽

2014 ◽

Vol 70 (a1) ◽

pp. C588-C588 ◽

Cited By ~ 1

Author(s):

Tomoya Kawaguchi ◽

Katsutoshi Fukuda ◽

Masatsugu Oishi ◽

Tetsu Ichitsubo ◽

Jun'ichiro Mizuki ◽

...

Keyword(s):

Structural Information ◽

Degradation Mechanism ◽

A Priori ◽

Deep Understanding ◽

Lithium Ion ◽

Structural Disorder ◽

Significant Shift ◽

Positive Electrodes ◽

Salt Structure ◽

Site Selective

Deep understanding of a battery reactivity of transition metals in a positive electrode is essential for further development of lithium ion batteries (LIBs). Li1-xNi1+xO2(LNO, 0 < x < 1) is one of the typical positive-electrodes with a layered rock-salt structure. LNO often contains significant antisite defects of Ni at Li site, i.e., interlayer gallery, in addition to Ni site in the host layer. Though a relationship between such structural disorder and capacity fading of the battery has been reported[1], its degradation mechanism is still unclear presumably because of insufficient insight into electrochemical behavior of Ni at each site in LNO. In the present work, powder diffraction anomalous fine structure (P-DAFS)[2] has been applied to LNO to analyze the valence and local structure of Ni at both different symmetric sites for tackling this degradation issue. We prepared pellets of as-synthesized and charged LNOs for P-DAFS measurements. The composition of the samples is [LiyNi0.11]3a[Ni]3b[O2]6c(y = 0.89, 0.40) in R-3m space group. DAFS measurements were carried out at undulator beamline BL28XU, SPring-8 in Japan. The DAFS spectra were measured with use of 003 and 104 diffractions in ~1 keV energy range around Ni K-edge (8.331 keV). The XAFS-like spectra were extracted from DAFS spectra with a priori structural information from Rietveld analyses. Figure 1 shows (a) the DAFS spectra of the as-synthesized sample, XAFS-like spectra of Ni occupying the Ni site (b) and the Li site (c) in the as-synthesized (solid line) and the charged (broken line) samples. The spectrum at the Ni site shows a shift to the higher energy with charging, indicating the oxidation of Ni accompanied with Li extraction. In contrast, Ni at the Li site shows no significant shift with charging. Thus, Ni at the Li site hardly compensates the charge for delithiation, which indicates that the electrochemically inactive Ni occupying the Li sites would cause irreversibility in this system.

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Ultraviolet photoluminescence from nonbridging oxygen hole centers in porous silica

Applied Physics Letters ◽

10.1063/1.1339844 ◽

2001 ◽

Vol 78 (2) ◽

pp. 174-176 ◽

Cited By ~ 55

Author(s):

Baodian Yao ◽

Huazhong Shi ◽

Xinyi Zhang ◽

Lide Zhang

Keyword(s):

Porous Silica ◽

Nonbridging Oxygen ◽

Oxygen Hole ◽

Hole Centers

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Luminescence of the surface nonbridging oxygen hole center in silica: Spectral and decay properties

Physical Review B ◽

10.1103/physrevb.78.075421 ◽

2008 ◽

Vol 78 (7) ◽

Cited By ~ 42

Author(s):

L. Vaccaro ◽

M. Cannas ◽

V. Radzig ◽

R. Boscaino

Keyword(s):

Nonbridging Oxygen ◽

Hole Center ◽

Decay Properties ◽

Oxygen Hole

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Unusual Luminescence of Quartz from La Sassa, Tuscany: Insights on the Crystal and Defect Nanostructure of Quartz

Minerals ◽

10.3390/min11121345 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1345

Author(s):

Giulia Ricci ◽

Andrea Maurizio Monti ◽

Renato Pagano ◽

Marco Martini ◽

Luisa Caneve ◽

...

Keyword(s):

Nonbridging Oxygen ◽

Hydrothermal Conditions ◽

Reference Case ◽

Oxygen Hole ◽

Icp Ms ◽

Trace Elements Analysis ◽

Significant Step ◽

Polycyclic Aromatic ◽

History Of ◽

Uv Lamp

Quartz from La Sassa (Tuscany, Italy) presents a unique luminescence related to intrinsic and extrinsic defects in the crystal lattice due to the growth mechanisms in hydrothermal conditions. The bright fluorescence under the UV lamp was apparent to collectors since the early 1970s, and it entered the literature as a reference case of yellow-luminescent quartz. Early reports present the history of the discovery, the geological context, and preliminary luminescence measurements of the quartz nodules, suggesting various activators as potentially responsible of the peculiar luminescence effects: uranyl groups (UO22+), rare earths (Tb3+, Eu3+, Dy3+, Sm3+, Ce3+) and polycyclic aromatic compounds (PAH). Here, we report a full investigation of the La Sassa material, by a multi-analytical approach encompassing cathodoluminescence optical microscopy (OM-CL), laser-induced fluorescence (LIF), wavelength resolved thermally stimulated luminescence (WR-TSL), trace elements analysis by mass spectrometry (ICP-MS) and Raman spectroscopy (RS). The results provide a significant step forward in the interpretation of the luminescence mechanisms: the main luminescent centres are identified as alkali-compensated (mainly Li+ and Na+, K+ and H+) aluminum [AlO4/M+]0 centres substituting for Si, where the recombination of a self-trapped exciton (STE) or an electron at a nonbridging oxygen hole centre (NBOHC) are active.

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