Influence of annealing temperature on material properties of red emitting ZnGa2O4: Cr3+ nanostructures

Optimization of Chromium-Doped Zinc Gallate Nanocrystals for Strong Near-Infrared Emission by Annealing

“…They achieved the best performance in LLP at 900–1000 °C annealing without significantly increasing the 15 nm particle size. In contrast, in ZGO:Cr NPs synthesized via the citric acid-assisted sol–gel method, a gradual increase in both the NP size and the emission intensity was found with annealing …”

Synthesis and characterization of a ZnGa2O4:Cr3+-based aerogel

“…The excited Cr 3+ electrons return to the ground state by emitting photons of different energy. 13,25 This produces a near-infrared long aerglow phenomenon which attribute to the sustained energy transfer of the host ZnGa 2 O 4 . 26 The degradation of methylene blue (MB) dye was measured as a function of irradiation time of ZnGa 2 O 4 :Cr 3+ -based aerogels, and samples with different calcination temperatures was also tested for comparison.…”

Molten‐Salt‐Assisted Annealing for Making Colloidal ZnGa2O4:Cr Nanocrystals with High Persistent Luminescence

“…As far as ZGOCNCs are concerned, a few studies have reported on undoped and Eu 3+ /Tb 3+ doped ZGO CNCs pertaining to light emitting phosphors but there is no report on ZGOC CNCs [39,40] . Generally speaking, to get desirable PersL properties from ZGOC NCs, one need to anneal them at a high temperature range of 650–750 °C which leads to particle agglomeration and size non‐uniformity as reported by several research groups earlier [16,19,20,25,26] . To overcome this obstacle, in the current study, we have introduced a new approach with a molten salt confinement concept to thermally anneal as‐synthesized ZGOC CNCs in a molten salt medium of NaNO 3 + KNO 3 at 650 °C for the first time.…”

“…Similarly, Hussen et al. enhanced PL intensity of ZGOC by annealing them at 1000 °C but increased its particle size from 12 to 31 nm which is highly undesirable [25] . On the similar ground, annealing ZGOC phosphor at 800 °C enhanced its PL intensity by an order of 6, but there was a large growth of particle size along with particle aggregation [26] …”

“…Here, we want to mention that maintaining the size and shape of ZGOC nanoparticles is utmost important as: i) When ZGOC is synthesized in nanodomain, higher PL intensity is shown compared to its agglomerated form (agglomerated NCs/microcrystals) [25] . ii) For optical imaging and information applications, sub‐10 nm particles are ideal as they can easily percolate through cells for bioimaging while exhibiting good dispersity in biological media and displaying negligible photobleaching [27] .…”