Content area
Full text
Adv. Manuf. (2013) 1:176182 DOI 10.1007/s40436-013-0018-1
Comparison of sol-gel and co-precipitation methodson the structural properties and phase transformation of c and a-Al2O3 nanoparticles
A. Rajaeiyan M. M. Bagheri-Mohagheghi
Received: 21 December 2012 / Accepted: 29 March 2013 / Published online: 11 May 2013 Shanghai University and Springer-Verlag Berlin Heidelberg 2013
Abstract The nanostructured c and a alumina powders were synthesized by sol-gel and co-precipitation methods, and properties of the powders were studied by XRD, SEM, TEM, BET and FTIR. The results showed that both c and a phases were formed in the lower temperature in precipitation method compared to sol-gel. The size of spherical aalumina synthesized by sol-gel was 1015 nm, whereas the sample prepared by co-precipitation yielded nearly spherical and hexagon a-powder with particle size of 1050 nm.
At 750 C the resulting powder prepared by co-precipitation exhibited larger surface area (206.2 m2/g) compared to sol-gel (30.72 m2/g), hence it is recommended for catalytic and sensing applications.
Keywords c and a-Al2O3 Co-precipitation sol-gel
Nanoparticles
1 Introduction
Nanoparticles of multi-phases materials refer to systems that their sizes are usually in the range of 1100 nm. These materials often exhibit novel chemical, electrical, optical, mechanical or magnetic properties, which are different from their bulk and the individual atomic constituents [1, 2]. Nanoscale materials also provide large surface areas compared with their micro and macro counterparts, which brings opportunities to function as adsorbents, catalysts, etc. [3].
Within all kinds of nanostructure materials, much attention is paid to the synthesis of nanocrystalline ceramics recently. It has shown that mechanical properties
of ceramics strongly depend on their nanostructure, which closely relates with the shape and size of the ceramic particles [4]. Among various ceramics, alumina, especially nanosized alumina is utilized in many areas of modern industry such as electronics, metallurgy, optoelectronics, ceramic composites, wear protection, refractories, catalysis (as catalytic supports and catalysts) in petroleum rening, automotive emission control and hydrogenation [510]. Alumina has many advantages, such as that it is hard, highly resistant towards bases and acids, allowing very high temperature applications and having excellent wear resistance [11, 12]. According to the arrangement of oxygen anions, this interesting ceramic material exists in two broad categories, including a face-centered cubic (fcc), and a hexagonal close-packed (hcp) arrangement. The Al2O3
structures...