Formation of patterned microstructures of polycrystalline ceramics from precursor polymers using micromolding in capilla
- PDF / 2,166,557 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 70 Downloads / 170 Views
MATERIALS RESEARCH
Welcome
Comments
Help
Formation of patterned microstructures of polycrystalline ceramics from precursor polymers using micromolding in capillaries Weng Sing Beh and Younan Xiaa) Department of Chemistry, University of Washington, Seattle, Washington 98195
Dong Qin Center for Nanotechnology, University of Washington, Seattle, Washington 98195 (Received 1 April 1999; accepted 29 July 1999)
Micromolding in capillaries has been used to generate patterned microstructures of ZrO2 or SnO2 from its polymeric precursor. After patterning, the amorphous precursor was converted into the desired polycrystalline ceramic material by calcination in air at 460 °C. The final phase for each ceramic material was determined by powder x-ray diffraction. The shrinkage of the precursor material during pyrolysis was investigated by scanning electron microscopy and atomic force microscopy. These ceramic microstructures could be either supported on solid substrates or released as freestanding fibers and membranes. Their lateral dimensions could be as small as approximately 500 nm.
I. INTRODUCTION
Polycrystalline ceramics are a class of highperformance materials with attractive properties ranging from extreme hardness, through high electrical or thermal conductivity, to unique magnetic, piezoelectric, pyroelectric, or electro-optic activities.1 The ability to pattern these materials into micrometer-sized structures should have a major impact on the development of miniaturized and/or highly integrated functional devices based on these functional materials. For example, piezoelectric ceramics such as lead zirconate titanate (PZT) have been widely used as active components in fabricating electromechanical transducers; the availability of a patterned array of microposts of PZT embedded in a polymeric matrix will make it possible to produce high-resolution microultrasonic transducers to be incorporated into portable medical instruments.2 Patterned microstructures of ceramics are usually fabricated from slurries of ultrafine powders by slip casting3 or from soft green pastes of ceramic powders in polymer binders by using procedures based on embossing,4 replica molding,5 and screen printing.6 Photolithography, machining, and other related microlithographic techniques are often used to fabricate the metallic masters, molds, or masks. The smallest feature sizes that have been achieved by these methods are in the range of
a)
Address all correspondence to this author. e-mail: [email protected] J. Mater. Res., Vol. 14, No. 10, Oct 1999
http://journals.cambridge.org
Downloaded: 20 Feb 2015
∼20 m, with a few demonstrations at the scale of ∼5 m. Some oxide ceramics (a typical example is SiO2) can also be directly patterned using a multiple-step procedure that involves uniform deposition of thin films by vapor-phase or liquid-phase techniques, followed by a combination of standard photolithography and selective chemical (dry or wet) etching. Although this method based on photolithography can routinely generate patterned
Data Loading...
