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The Materials Characterization Lab works at technology readiness levels that cover the spectrum from the fundamental (quantum physics, superconductivity, metamaterials) to the applied (electronics, coatings, targeted drug deliver). MCL is training the next generation of skilled engineers and scientists for the workplace of the future. From fundamental to applied, we offer a wide range of characterization techniques complimented with other capabilities in materials processing.
A heated platen press is available to laminate a variety of materials at different temperatures and pressures. Temperature can be set for the top and bottom platens, with the maximum temperature at 200°C. Lamination area is roughly 6 by 8 inches, and maximum pressure is 40,000 pounds.
We have 2 presses available. These presses use warm water as a medium to evenly apply a set pressure to a sample which is vacuum-bagged. The temperature ranges from room temp up to 80°C, pressure ranges from 0 to 5000 psi. Our smaller press will accept parts up to 3.5 by 8 inches. The large press will accept parts to 12 by 12 inches. Typical lamination conditions for ceramic tapes are 70°C, 3000 psi, for a holding time of 10 to 45 minutes.
For various analytical techniques, samples may need to be cut, shaped, polished, hole-punched, and/or prepared to allow for testing. MCL maintains a complete sample preparation lab for mechanical cutting and polishing including a variety of polishing equipment, diamond saws, a dicing system, ion mills, microscopes, heaters, cleaners, hand files, and measuring tools. Basic prep and polish supplies such as sandpaper, slurries, pastes, and powders are also provided.
Sample requirements vary widely with instrument, material type, and for the specific testing required. Please consult the technical staff for sample requirements/specifications for your project.
Specific instruments may have training requirements before independent use is allowed. Please inquire about training requirements with the technical staff before proceeding to use the instruments.
TEM samples must be electron transparent. This means they must be thin - typically about 100 nm or less depending on the average atomic number of the material. Certain types of investigations demand more stringent requirements such as thickness on the order of 20 to 30 nm. It is impossible to anticipate every sample preparation problem. However, there are three common types of samples.
Desirable particle size is about 500 nm or less. Powders that are more coarse than this should be ground with a mortar and pestle. The specimen preparation consists in transferring a suspension of the particles in a solvent such as isopropanol to a carbon coated grid and letting the solvent evaporate.
The preparation process can sometimes be time-consuming and often requires careful grinding and polishing techniques, skills for which may take time to develop. We recommend that the person studying the sample is the same one preparing the sample.
All of our TEM holders accommodate a 3-mm disc. Ultimately, the TEM sample you prepare will be in the form of such a disc. It may be monolithically cut from bulk material. Alternatively, a small (< 3 mm) fragment can be thinned and mounted on an appropriate support.
Simple metals or single-phase alloys can often be electropolished with an appropriate electrolytic solution. Even multiple phase alloys can sometimes be prepared in this fashion.
More commonly, samples from bulk material are thinned with an ion beam. Before the final ion-beam thinning, however, the sample should be first mechanically thinned by lapping and polishing so that the final thickness in the center of the sample is about 30 microns.
Cross-section samples can usually be made using the same ion-thinning process as for bulk samples. However, one must first make a stack by gluing together two substrate fragments film-to-film. Then a cross-section can be cut or simply ground down with lapping film. Final preparation is with ion thinning as described above.
Occasionally the need arises to prepare TEM samples from a specific location on or near the surface of a bulk sample or thin film sample. In order to achieve such site specificity, we recommend the use of the Focused Ion Beam instrument for sample preparation.
To facilitate the development and characterization of materials, MCL operates a general use computer controlled furnace facility with a verity of furnace types and temperature ranges. A user friendly interface allows operators to program desired temperature profiles (within the given limits of a specific furnace) up to 20 segments and record the achieved result.
There are two high temperature 1600°C bottom loading box furnaces, Three mid-range 1400°C box furnaces, five lower range 1150°C box furnaces, and three 1400°C tube furnaces.
Tube furnaces allow firing in various atmospheres and use slower heating and cooling rates than box furnaces. Allowable atmospheres include Nitrogen, Argon, Air, Oxygen, and Safe Gas (5% or less Hydrogen - balance Nitrogen or Argon).
Box furnace heating capabilities vary between units. Most box furnaces have gas inlets to allow a rough modification of the atmosphere. Allowable gases are the same as tube furnaces.
Nitrogen, Argon, and Oxygen is provided by the facility and always available for use.
Sample size is not critical and varies depending on the specific furnace used. In general, samples should be within two or three inches in the longest dimensions. Oversized loads can cause non uniform firings. Appropriate temperature rated user supplied lab ware should be utilized to hold/contain samples in furnaces.
| Box Furnaces | Chamber Dimensions | ||
|---|---|---|---|
| Two 1600°C | 7.50" (H) | 6.00" (Dia.) | |
| Three 1400°C; | 6.75" (H) | 6.75" (W) | 10.75" (D) |
| Four 1150°C | 5.25" (H) | 5.50" (W) | 10.00" (D) |
| One 1150°C | 10.00" (H) | 12.50" (W) | 17.75" (D) |
| Tube Furnaces | |||
|---|---|---|---|
| Three 1400°C | 2.00" I.D. | 7.00" heated zone | |
The Electrical Characterization Lab houses a Quorom EMS 150 Sputter Coater which is used to deposit a thin metal film on various surfaces. The system is ideal for depositing conductive coatings on scanning electron microscopy (SEM) specimens or depositing noble metal electrodes on bulk ceramics or polymers. Gold, platinum and silver metal coatings are available.
The EMS 150T is a compact turbomolecular-pumped coating system that is suitable for SEM, TEM, and many thin-film applications.
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