In situ local environment and partitioning of Ni 2+ ions during crystallization of an oxyfluoride glass

Abstract

The local structure of Ni 2+ ions during crystallization of an oxyfluoride aluminosilicate glass was examined by high temperature in situ spectroscopic experiments coupled with in situ X-ray diffraction to characterize the different crystallization steps. We show that Ni 2+ ions in the glass are located in the silicate glass network. After heat treatment Ni 2+ ions do not partition into the fluorine crystallites as observed for rare-earth metals. Instead, we observed the crystallization of a NiAl 2 O 4 crystalline phase, a largely inverse spinel. The in situ spectroscopic results (XRD, UV-Vis-NIR and Ni K-edge XANES) give new insights on the nickel partitioning between the supercooled liquid and the new crystals and show that the inversion degree of NiAl 2 O 4 spinel during its crystallization depends not only on the temperature but also on the annealing timescale. We also show that the addition of fluorine into aluminosilicate systems favors the formation of spinel crystals at lower temperature than usually observed, thereby playing a role to promote nucleation. *

Selective doping of Ni2+ in highly transparent glass-ceramics containing nano-spinels ZnGa2O4 and Zn1+x Ga2−2x Ge x O4 for broadband near-infrared fiber amplifiers

“…S3 , supporting information). It is possible that a certain degree of inversion may occur in realistic spinels during crystallization, i.e., a fraction of the Ni 2+ can occupy non-luminescent tetrahedral sites as found in NiAl 2 O 3 crystals 33 , 34 , and hence the selective doping of Ni 2+ in octahedral sites is highly desirable for enhanced NIR luminescence 33 .…”

Impact of high NiO content on the structural, optical, and dielectric properties of calcium lithium silicate glasses

“…In amorphous matrices, nickel ions are very stable and mainly occupy octahedral sites. The spectroscopic properties of Ni 2þ ions in glasses are remarkable due to their high stability, and various intensive investigations into these materials are present in the literature [3][4][5].…”

Nanoscale composition fluctuations and crystallization process: Case study in Li2O–SiO2‐based glasses

“…[123][124][125][126] It is of interest and importance to clarify the behavior of TM ions during the nanocrystallization of glasses. [143][144][145] In particular, the local environment of doped TM ions in glasses would be a key point to understand the incorporation behavior of TM ions into nanocrystals. In this section, we mainly focus on Ni 2+ ion sites in nanoscale composition fluctuations.…”

“…It has been well recognized that the incorporation of transition metal (TM) ions such as Ni 2+ and Co 2+ ions into nanocrystals is one of the most important techniques leading to the synthesis of transparent glass–ceramics with excellent photoluminescence properties 123–126 . It is of interest and importance to clarify the behavior of TM ions during the nanocrystallization of glasses 143–145 . In particular, the local environment of doped TM ions in glasses would be a key point to understand the incorporation behavior of TM ions into nanocrystals.…”