Materials Sample Preparation for TEM - Why choose sectioning techniques?
Dr Jeremy Rees, RMC Products, Tucson AZ, USA
Dr Ilaria Zamproni, Emme3 s.r.l., Mazzo di Rho, Milano, Italia
The aim of sample preparation for TEM is to produce a specimen from a material that is stable, electron transparent and is representative of the bulk. There are many attributes of a “good” sample that include; electron transparency, mechanical, thermal and electrical stability and tolerance to vacuum.
There are many ways of producing samples for TEM, ranging from simply drying suspensions onto TEM grids, mechanical methods such as polishing, chemical methods and ion-based methods such as ion milling and FIB. However, ultramicrotomy is often not thought of as a potential solution. For the materials researcher, ultramicrotomy can be used for a wide range of samples such as polymers, metals, ceramics and semiconductors. It is also a uniform and chemically benign technique. Advantages of ultramicrotomy include; no use of polishing compound and associated scratches, no chemical etching, no ion Implantation and minimal temperature effects. Sections can be of very uniform thickness and of a relatively large area; often the researcher can quite precisely select the sample location. We will show results of ultramicrotomy on samples that include; semiconductors, multilayers, paint, mineral and catalysts. Certain materials samples are best sectioned at low temperatures and examples of cryosectioned rubbers, polymers, starch grains and hydrogels will be discussed. Ultramicrotomy is a very versatile and benign method of sample preparation for a wide range of materials samples.
We will show the latest technology in ultramicrotomy that includes new levels of automation and even unattended serial sectioning for array tomography (“volume” microscopy) applications. Sections are imaged in a modern FEG SEM equipped with an automated array tomography system that facilitates analysis of thousands of sections at a high resolution.
