Graphene Quantum Dots-Driven Multiform Morphologies of β-NaYF₄:Gd³⁺/Tb³⁺ Phosphors: The Underlying Mechanism and Their Optical Properties

Abstract

Dimension and shape tunable architectures of inorganic crystals are of extreme interest because of morphology-dependent modulation of the properties of the materials. Herein, for the first time, we present a novel impurity-driven strategy where we studied the influence of in situ incorporation of graphene quantum dots (GQDs) on the growth of β-NaYF 4 :Gd 3+ /Tb 3+ phosphor crystals via a hydrothermal route. The GQDs function as a nucleation site and by changing the concentration of GQDs, the morphology of β-NaYF 4 :Gd 3+ /Tb 3+ phosphors was changed from rod to flowerlike structure to disklike structure, without phase transformation. The influence of size and functionalization of GQDs on the size and shape of phosphor crystals were also systematically studied and discussed. Plausible mechanisms of formation of multiform morphologies are proposed based on the heterogeneous nucleation and growth. Most interestingly, the experimental results indicate that the photoluminescence properties of β-NaYF 4 :Gd 3+ /Tb 3+ phosphor crystals are strongly dependent on the crystallite size and morphology. This study would be suggestive for the precisely controlled growth of inorganic crystals; consequently, it will open new avenues and thus may possess potential applications in the field of materials and biological sciences.

Study of Growth Kinetics of Fe3Se4 Nanocrystallites and the Influence of Size and Shape Tunability on their Magnetic Properties

“…These results can be related to the “morphological importance” (MI) of respective lattice planes, which for a particular crystal is inversely proportional to the growth rate, i.e., the faster the growth rate of a plane, the lower the MI value of that plane and vice versa. Thus, the slow-growing facet will dominate the morphology in the resultant particle with a large surface area and is more exposed to the environment . These more exposed planes will contribute toward a higher RI in the XRD pattern, so the RIs of crystalline peaks can be directly related to the MIs of respective lattice planes, which immediately makes the growth direction in a distinct environment accessible to us.…”

“…Thus, the slow-growing facet will dominate the morphology in the resultant particle with a large surface area and is more exposed to the environment. 52 These more exposed planes will contribute toward a higher RI in the XRD pattern, so the RIs of crystalline peaks can be directly related to the MIs of respective lattice planes, which immediately makes the growth direction in a distinct environment accessible to us. This important information by using the simple exercise actually gives us a direct link between the crystal formation and tunable reactionlimited growth conditions that were carefully selected in this report.…”

Multifunctional Lanthanide-Doped Binary Fluorides and Graphene Oxide Nanocomposites Via a Task-Specific Ionic Liquid

“…Similarly, Malik et al discloses the incorporation of graphene quantum dots (GQDs) on the growth of β-NaYF 4 :Gd 3+ /Tb 3+ phosphor crystals via a hydrothermal route. 53 The GQDs function as a nucleation site, and by changing the concentration of GQDs, the morphology of β-NaYF 4 :Gd 3+ / Tb 3+ phosphors was changed from a rod to flowerlike to disklike structure, without a phase transformation. Likewise, Wei et al synthesized GO−NaYF 4 :Yb/Er nanocomposites in the water/ethanol (1:1, v/v) solution.…”

Study of the Phase-Evolution Mechanism of an Fe–Se System at the Nanoscale: Optimization of Synthesis Conditions for the Isolation of Pure Phases and Their Controlled Growth

“…As we proceed toward the nanoscale dimensions, materials can showcase different physical and chemical properties from those of their bulk counterparts. For this reason, understanding the nucleation and growth processes is vital for the cogent design of functional nanoparticles (NPs) with precise composition, crystalline phase, size, and shape for the applications in medicine, catalysis, nanoelectronics, and so forth. − With advancements in the characterization techniques, it is possible to microscopically and spectroscopically observe the nucleation and growth at time and light-scales, which were inaccessible earlier, giving us newer insights for phase control . Several synthetic pathways have been designed and optimized for better phase-control of miscellaneous inorganic NPs .…”