CeF3 nanoparticles: synthesis and characterization

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Abstract

CeF3 nanoparticles 5–10 nm in size were prepared using the polyol method. CeCl3 and HF were heated up in ethylene glycol. At a temperature of 180 °C crystalline CeF3 nanoparticles were formed. The material was washed with ethanol, centrifugated and dried. The particles were characterized by EDX, XRD and TEM.

Introduction

A number of exciting size- and surface-dependent properties of nanometer-sized semiconductor particles, which lie between molecular and bulk forms of matter, have stimulated an exponential development of nanochemistry and nanophysics.

Cerfluoride nanoparticles attracted interest for academic reasons, because of their Faraday effect, which is applicable to optoelectronics such as an optical isolator, optical switches or optical memory [1]. As Cerflouride nanoparticles exhibit a high Faraday effect combined with very low absorption in the visible they are well qualified for magneto-optical applications.

Extensive research work was carried out in the field of synthesis and characterization of semiconductor nanoparticles [2], [3], [4], [5], [6], [7]. In the case of particles consisting of rare earth materials only few investigations are known. The sol–gel technique was used to produce nanoparticles of Tb2O3 [8] and rare earth doped yttria [12]. In spite of their interesting properties and potential applications no synthesis of well defined CeF3 is known. Feldmann et al. [9], [10], [11] developed the so-called polyol process to synthesize nanoscale oxide, sulfide and phosphate materials. The surface of the nuclei is complexed by polyol medium right after formation which limits the growth of particles and stabilizes them against agglomeration.

We report here about the synthesis and charcterization of monodisperse cerfluoride nanoparticles by polyol technique.

Section snippets

Synthesis

CeF3 particles were prepared by first suspending 200 mg CeCl3 in 100 ml diethylene glycol in a teflon flask. Afterwards a mixture of 0.8 ml of an aqueous solution of 40% HF in 10 ml ethanol was added and the mixture then heated in a silicon oil bath to 180 °C under reflux for 2 h. After 2 days the mixture became turbid. After two more days the CeF3 was separated via centrifugation and washed three times with ethanol to remove the chloride ions and the diethylene glycol. The yield of the reaction is

Results and discussion

Fig. 1, Fig. 2 show a typical TEM overview of CeF3 nanoparticles. The average size estimated from TEM micrographs was 5 nm. The photo shows that most of the nanoparticles are single particles and that only a few particles are agglomerated.

EDX measurements on CeF3 nanoparticles indicated the presence of Ce and F in a ratio of 1:3, and in addition, 2% C due to the ethylene glycol which stabilises the individual particles in the solution as well when the particles are dried.

Powder X-ray diffraction

Acknowledgements

We gratefully acknowledge A. Weidenkaff (University of Augsburg) for the HRTEM measurements. We kindly acknowledge access to characterization techniques in the groups of Professors Felsche and Rathmayer. This work was performed with the financial support from the DFG (SPP 1113, MA 817/5-3).

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