Stable nanocrystalline zirconia sols prepared by a novel method: Alcohol thermal synthesis
- PDF / 307,211 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 59 Downloads / 161 Views
MATERIALS RESEARCH
Welcome
Comments
Help
Stable nanocrystalline zirconia sols prepared by a novel method: Alcohol thermal synthesis Junping Zhao, Wenhao Fan, Dong Wu, and Yuhan Suna) State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, 030001, People’s Republic of China (Received 23 August 1999; accepted 9 November 1999)
Nanocrystalline zirconia sols with a metastable cubic phase were synthesized from diglycol-modified zirconium n-propoxide via a novel method, alcohol thermal synthesis. The chemical bonding of diglycol with zirconium was found to be important in obtaining stable nanocrystalline zirconia sols. Sols produced in this way were translucent with the primary particles of 4-nm crystallites, and the corresponding gel was shown to be mesoporous with a pore size from 2.5 to 3.8 nm and Brunauer–Emmett–Teller surface areas between 130 and 266 m2 g−1. This indicates that alcohol thermal synthesis shares the advantages of both the sol-gel process and hydrothermal synthesis.
I. INTRODUCTION
Preparation of nanocrystalline metal oxides and their composite thin films are currently attracting much interest because of their wide applications in optical, electric, magnetic, and thermal fields.1 Among various synthesis methods, hydrothermal treatment and the sol-gel process are usually used to prepare thin films with high purity at relatively low temperature. However, hydrothermal synthesis mainly leads to the production of nanocrystalline powders, and then a complicated post-treatment is necessary to prepare nanocrystalline thin films.2 The sol-gel method can be used to produce amorphous coatings with modified physicochemical properties by adding various additives,3 but the post-treatment at relatively high temperatures is usually inevitable for crystallization. Thus, a new method has to be developed for soft production of crystalline thin films. In this work, in view of the importance of ZrO2-based materials in practical applications a novel method was developed to prepare nanocrystalline zirconia sols. Combining the sol-gel method with hydrothermal synthesis, called alcohol thermal synthesis, nanocrystalline sols could be directly obtained. Alcohol thermal synthesis is expected to share the advantages of hydrothermal and sol-gel processes, allowing both preparation of nanocrystalline sols and physicochemical modification of their structures.
a)
Address all the correspondence to this author. e-mail: [email protected]
402
http://journals.cambridge.org
J. Mater. Res., Vol. 15, No. 2, Feb 2000 Downloaded: 19 Mar 2015
Here zirconium n-propoxide was used for the preparation because of its reactivity toward water and because it is a typical representative of metallic alkoxides. Additives such as acetic acid,4 glycol,5 and acetylacetone6 were used to control hydrolysis. To obtain stable sols without precipitation during alcohol thermal treatment at relatively high temperatures, diglycol [O(CH2CH2OH)2] was chosen to reduce the reactivity of z
Data Loading...
