Pre-crystallization heat treatment and infrared luminescence enhancement in Ni2+-doped transparent glass-ceramics

Abstract

We report on design and fabrication of Ni 2+-doped glass-ceramics from a low-alkali optical glass in Li 2 O-Na 2 O-Ga 2 O 3-SiO 2-GeO 2 system by melting technique and subsequent thermally controlled nano-crystallization. The analysis of differential scanning calorimetry, X-ray diffraction, transmission electron microscopy, absorption and fluorescence spectroscopy reveals, for the first time, the real possibility of optimizing the integrated intensity of Ni 2+ near-infrared emission through controlled pre-treatments at temperatures of nanophase nucleation, with the enhancement up to a factor of four with respect to gallium germanosilicate glass-ceramics obtained without pre-treatments. Importantly, the effects on the light emission are shown to be related to the influence of pre-treatment on size and size distribution of the gallium oxide nanocrystals which result from subsequent crystallization at higher temperature.

Correlation between degree of crystallinity and bluing of Zn1–Co Al2O4 (0≤x≤1) nanopowders prepared by soft chemistry route

“…In the visible region, the spectra of the cobalt-enriched powders (x=0.5 and x=1) show a triplet of bands at 550, 590 and 680 nm. These absorptions are ascribed to the 4 A 2 (F) 4 T 1 (P) transition of Co 2+ ions in tetrahedral symmetry which gives a blue hue to the samples [33].…”

“…Among these materials, the transition metal oxides which generally have different colours. Their absorption properties are governed by the degree of oxidation of the transition metal and by its environment in the crystal lattice [1][2][3][4]. Usually the main source of the blue colour is the cobalt that can be introduced in different structures, such as Co 2 SiO 4 (olivine) [5], (Co, Zn) 2 SiO 4 (willemite) [6,7] and CoAl 2 O 4 (cobalt spinel) [8].…”

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

“…Indeed, Ni 2+ -doped LiNbO 3 crystals have received much attention, in which octahedral Ni 2+ ions have been proposed to occupy distorted octahedral Nb 5+ sites. 147 In the transparent glass-ceramics consisting of Ni 2+ /Co 2+ -doped LiGa 5 O 8 nanocrystals in NiO/CoO-doped Li 2 O-Ga 2 O 3 -SiO 2 -based glasses, [123][124][125][126]129 it is strongly expected that Ni 2+ /Co 2+ ions are present mainly in the fragile Li 2 O-Ga 2 O 3 -rich region, resulting in the enhancement of the formation of Ni 2+ /Co 2+ -doped LiGa 5 O 8 nanocrystals, as being similar to the case of LNS glasses (Figure 8). The proposed site position of Ni 2+ /Co 2+ ions in the DNCF model for LGS glasses is included in Figure 7.…”

Effect of Gold Nanoparticles on the Crystallization and Optical Properties of Glass in ZnO-MgO-Al2O3-SiO2 System

“…The phases formed in glass-ceramics can be oxide and non-oxide crystallites, metal nanoparticles (NPs), clusters, or semiconductor quantum dots [4]. The precipitation of different crystallites in transparent glass-ceramics is being actively studied to develop new light-emitting and laser media [5][6][7], materials with controlled values of the thermal expansion coefficient [8], and high-strength transparent cover materials [9][10][11]. Similarly, glass-ceramics based on metal NPs (mainly silver or gold) are in great demand as new nonlinear optical and plasmonic materials [12][13][14][15][16].…”