ZnO microtubes
- PDF / 2,928,347 Bytes
- 4 Pages / 576 x 792 pts Page_size
- 55 Downloads / 152 Views
Microtubes of ZnO have been produced using sputter coating and a fugitive phase technique. ZnO was sputtered onto polyester fibers by dc magnetron sputtering, and the polyester fiber fugitive phase was subsequently burned out by annealing in air or oxygen. Tubes with an inside diameter of 23 jam and a length of 3 cm were obtained. The 3 to 6 yu.ni thick walls of the tubes exhibited a [002] radial texture.
Micromechanical devices that provide mechanisms for controlled motion on the micron and nanometer scale will require a wide variety of three-dimensional structures or components in order to perform a wide range of functions. In devices that include transport of liquids or gases, tube structures are likely to be of great importance. Tubes constructed from electrically, magnetically, or optically active materials also provide a means for incorporating sensors or actuators within the tube structure. Tubes with diameters in the millimeter size range or smaller are generally formed by drawing or extrusion processes. Drawing can be used to produce tubes with diameters in the micron and nanometer size ranges, but this technique is most commonly applied to glasses or polymers that can be drawn in the viscous state and then solidified.1-2 Single crystal tubes down to the 100 yu-m size range can be drawn directly from the melt.3 Polycrystalline tubes as small as 10 pun in diameter have been prepared by extrusion, followed by sintering, but this process requires the development of binder systems and high temperatures for densification.4 Sol-gel techniques have also been used to produce polycrystalline ceramic tubes, although the proper chemistry for tube formation must be developed for each materials system.5 Thin film coating processes can be extended to produce three-dimensional tube structures or hollow structures by employing fugitive phase techniques. A fugitive phase is a second phase that is incorporated within a structure during the forming process and is then removed while leaving the surrounding structure intact. With formation of ceramic structures that utilize the fugitive phase technique, it is common to employ a polymer or organic fugitive phase with a low decomposition temperature. The organic fugitive phase is burned out prior to or during sintering of the ceramic body.6'7 Hollow infrared waveguides with diameters down to the 100 yum size range have been produced by utilizing a metal or polymer tube fugitive phase that is sputter coated, electroplated, and subsequently etched away.8"10 A similar technique can easily be applied to the formation of hollow structures of defined shape and size in J. Mater. Res., Vol. 9, No. 11, Nov 1994
the micron-size range. The fugitive phase can be coated by any thin film deposition process and subsequently removed, leaving behind a shell defined by the size and shape of the fugitive phase and the thickness and uniformity of the coating. Mechanical integrity of the hollow structure will depend on the wall thickness, size, shape, and strength of the coating material, as is th
Data Loading...