Oleic Acid/Oleylamine Cooperative-Controlled Crystallization Mechanism for Monodisperse Tetragonal Bipyramid NaLa(MoO₄)₂ Nanocrystals

Abstract

A straightforward hydrothermal strategy for the controlled synthesis of monodisperse NaLa(MoO4)2 and NaLa(MoO4)2:Eu3+ bipyramid nanocrystals is presented using oleic acid/oleylamine as a mixed surfactant. Deprotonated oleic acid was demonstrated to be the decisive structure-directing agent for the bipyramid nanocrystals, and the bipyramid formation efficiency of the oleic acid/oleylamine combination was found to be the highest among the selected surfactant combinations. The roles of oleylamine in the synthesis of monodisperse bipyramid nanocrystals were elucidated. A possible oleic acid/oleylamine cooperative-controlled crystallization mechanism (CCM) for the growth of uniform tetragonal bipyramid NaLa(MoO4)2 nanocrystals is proposed on the basis of our experimental results. The formation of well-defined tetragonal bipyramid morphology is mainly due to the preferential adsorption of deprotonated oleic acid onto {101} and {001}, which changes the surface energy of crystal planes and leads to different growing rates along corresponding directions, while facilitating the formation of bipyramid morphology with exposed {101} faces. Fluorescent investigation revealed that NaLa(MoO4)2:Eu3+ bipyramid nanocrystals possess a dominated hypersensitive red emission 5 D 0 → 7 F 2 transition of Eu3+ at 613 nm.

Porous olive-like BiVO4: Alcoho-hydrothermal preparation and excellent visible-light-driven photocatalytic performance for the degradation of phenol

“…In recent years, organic compounds, such as oleic acid (OA), oleylamine (OL), and dodecylamine (DA), have been employed as surfactant [30,31] or stabilizing agent [32] for the making of inorganic nanoparticles [30][31][32]. Up to now, however, no reports have been seen in the literature on the preparation of monoclinic BiVO 4 nano/microparticles with regular morphologies and/or porous structures using OA, OL or DA as surfactant.…”

Luminescence and magnetic properties of novel nanoparticle-sheathed 3D Micro-Architectures of Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) for bifunctional application

“…According to the Donnay-Harker rules, for tetragonal structures, the surface free energy of the [001] face is higher than that of the [101] face. [21,22] As a result, the faster growth rate in the assembly. The formed 2D nanoparticles are constantly selfaggregated via a layer-by-layer stacking style to form quasibipyramidal bases for the subsequent growth of 3D bipyramid structures.…”

Hydrothermal synthesis of NaY(WO4)2:Tb3+ powders with assistance of surfactant and luminescence properties

“…It is one of particular interests to synthesize nano/microcrystals with complex and uniform morphologies by investigating the important parameters for selective growth and ultimate shape determination and to uncover their novel properties [11]. And the use of single or multiple surfactants in the synthesis have shown great success in controlling the size and morphology of nano/microcrystals [12].…”