Low-temperature solvent thermal synthesis of cubic AlN

doi:10.1016/S0022-0248(03)01553-7

Journal of Crystal Growth

Volume 258, Issues 3–4, November 2003, Pages 268-271

https://doi.org/10.1016/S0022-0248(03)01553-7 Get rights and content

Abstract

AlN nanoparticles have been successfully synthesized by the reaction of AlCl₃ and NaN₃ in organic solvent at low temperature (280°C). After being sintered at 700°C for 48 h, pure phase cubic AlN nanocrystals were produced. All X-ray diffraction, Fourier transformation infrared spectroscopy and selective area electron diffraction measurement results have confirmed that pure phase cubic AlN were obtained by this method. In addition, the morphology showed that the particles were in cubical shape and the average size was about 3 nm.

Introduction

Aluminum nitride (AlN), being a wide band gap III–V semiconductor material, has attracted wide attention for its numerous considerable attractive properties such as high thermal conductivity, low-thermal expansion coefficient, relatively low-dielectric constant, excellent chemical stability and good mechanical strength [1], [2], [3], [4], [5].

A number of methods have been used to synthesize AlN powders, including nitrating Al₂O₃ or Al [6], [7], [8], thermal plasma processing [9], [10], [11], [12], and vapor phase reaction of ammonia with aluminum chloride, aluminum fluoride, or tri-isobutyl aluminum [13], [14], [15], [16]. Most of the methods need high temperature and complex processes. And generally the product is wurtzite AlN, not zinc-blende cubic AlN, which is believed to have superior properties. Little information about pure cubic AlN nanocrystals synthesis is available to date.

We have already reported the synthesis of AlN nanocrystals (in both hexagonal and cubic phases) in organic solvent with AlCl₃ and Li₃N as predecessors [17] and its catalytic effect on the polymerization of benzene [18]. In this paper, we gained fairly pure phase cubic AlN nanocrystals by sintering the sample which was synthesized by a solvent thermal method at low temperature.

Section snippets

Experimental procedure

AlN nanocrystals were prepared in a stainless steel autoclave with xylene as the solvent. The reaction can be expressed as $AlCl_{3} +3 NaN_{3} = AlN +3 NaCl +4 N_{2}$ Proper AlCl₃ and NaN₃ were mixed and transferred into an autoclave, and the distilled xylene was placed into the autoclave to a filling ratio of 60%. All these manipulations were conducted under oxygen- and water-free conditions in a glove box. Then the autoclave was sealed and heated to 280°C for 6 h, and cooled to the room temperature naturally. The

Results and discussion

Fig. 1(a) and (b) shows the XRD patterns of Samples 1 and 2. It can be seen that there were no obvious diffraction peaks in Fig. 1(a). This phenomenon showed that the sample was amorphic. However, the reflections of sample 2 are very different from that of sample 1. There are obvious diffraction peaks in Fig. 1(b). And it can be indexed to zinc-blende AlN with a lattice constant of a=0.7932 nm, which is very close to the reported data [19]. No other phase is detected. The broadening nature of

Conclusions

Very pure cubic AlN nanocrystals are prepared after sintering the sample synthesized by the solvent thermal method at low temperature. The XRD, FTIR and selective area electron diffractions verify that the cubic AlN sample is in a good dispersion of size and has high purity.

Acknowledgements

This project was supported by the NSFC (Contract No. 60025409, 90101016, 50272036, 90206042), Natural Science of Shandong Province (NSFSD).

References (21)

R. Bachelard et al.
J. Mater. Sci.
(1989)
T. Reier et al.
Surf. Coat. Technol.
(1998)
G.A. Slack et al.
J. Phys. Chem. Solids
(1987)
A.V. Virkar et al.
J. Am. Ceram. Soc.
(1989)
L. Zheng et al.
J. Vac. Sci. Technol. A
(1993)
M.M. Seibold et al.
J. Am. Ceram. Soc.
(1989)
Y. Baik et al.
J. Am. Ceram. Soc.
(1989)
J.A. Haber et al.
Chem. Mater.
(1998)
J.A. Haber et al.
J. Am. Chem. Soc.
(1997)
Seung-Min Oh, Dong-Wha Park, Thin solid films 316 (1998)...

There are more references available in the full text version of this article.

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Low-temperature solvent thermal synthesis of cubic AlN

Abstract

Introduction

Section snippets

Experimental procedure

Results and discussion

Conclusions

Acknowledgements

J. Mater. Sci.

Surf. Coat. Technol.

J. Phys. Chem. Solids

J. Am. Ceram. Soc.

J. Vac. Sci. Technol. A

J. Am. Ceram. Soc.

J. Am. Ceram. Soc.

Chem. Mater.

J. Am. Chem. Soc.