Hydrothermal Synthesis of Complex Fluorides NaHoF₄ and NaEuF₄ with Fluorite Structures under Mild Conditions

Abstract

The complex fluorides NaHoF 4 and NaEuF 4 with fluorite structures were hydrothermally synthesized and characterized by means of X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis, and infrared spectroscopy.

Synthesis of nanocrystalline mixed metal fluorides in nonaqueous medium

“…Traditionally complex fluorides are prepared by solid state reaction at high temperature (>400°C) and high pressure or by high pressure (>100 MPa) hydrothermal technique (Demiamets 1990). A milder hydrothermal synthesis of the complex fluorides at 120-240°C has also been reported (Zhao et al 1996(Zhao et al , 1997Xun et al 1997Xun et al , 1998. The major difficulties that are encountered in the synthesis of fluoride perovskites are the choice of the container, the evolution of hydrofluoric acid (HF) and the corrosive nature of the fluorine gas which also may lead to the non-stoichiometry of the products.…”

Selected synthesis of cubic and hexagonal NaYF4 crystals via a complex-assisted hydrothermal route

“…A flux growth method [12] and a high-temperature, high-pressure hydrothermal technique [13] which needs rigorous synthesis conditions, complicated apparatus and long reaction time have also been reported. Recently, the co-deposition method and the hydrothermal method have been used to synthesize NaLnF 4 nano-and microcrystals [4,[14][15][16][17][18][19][20][21][22].…”

Enhanced blue and green upconversion in hydrothermally synthesized hexagonal NaY1−xYbxF4:Ln3+ (Ln3+ = Er3+ or Tm3+)

“…Demianets's group [12] used high temperature (450-550 • C) hydrothermal method to synthesize some single crystals in system AF-BF 3 (A = alkaline metal, B = rare earth element). Feng and co-workers exploited a milder hydrothermal route (below 240 • C) to synthesize complex fluorides [13][14][15][16].…”