SCHOTT solutions no. 2/2013 > Research & Development

The scanning electron microscope Neon 40 helps SCHOTT researchers to find answers to difficult questions on developmental and damage analysis more quickly. The photos to the right show how a sample is placed inside the system. Photo: SCHOTT/C. Costard

Detective Work in the Nano World

A high-performance scanning electron microscope enables SCHOTT to work even harder on exploring and developing micro- and nano-structured materials and products. Even the surfaces of various types of material combinations can be prepared down to the nano level.

Thilo Horvatitsch

The image on the screen shows the fissured surface of a plastic foil with integrated glass particles in micrometer resolution through the electronic beam optics of the ”Neon 40” scanning electron microscope from Zeiss. The material combination shown here helps our company to manufacture a special separator foil for the energy storage systems of the future. The scanning electron microscope itself is also highly sophisticated. It not only allows for high resolution imaging of samples as small as 1.1 nanometers with the scanning electron microscope (SEM), but the focused ion beam (FIB) optics that are aligned diagonally to the electron beam also allow for preparation of the smallest surface structures by scraping off small amounts of material. Cuts through or exposure of material surfaces are possible down to the nano level with the FIB. In fact, they can be examined and prepared at the same time with the SEM and the FIB.
The photos show how a sample is placed inside the system. Photo: SCHOTT/C. Costard
A mixed type – such as brittle, porous glass embedded in a ductile (plastically preformed) polymer matrix – could never be processed using traditional techniques such as grinding, polishing, breaking or cutting, without destroying or altering the material structure. For use in innovative rechargeable batteries, the goal is to manufacture the separator material to be as thin as possible.  After all, the thinner the foil, the higher the energy density of the battery. At the same time, however, its mechanical, chemical and temperature stability needs to be maintained. Here, the Neon 40 helps us learn more about surface structures in order to ultimately be able to improve them, by determining the right degree of porosity of a material, for example. ”Our research and development is in need of clear images and information on materials and structures that we can work with. Otherwise, we won’t be able to make progress,” emphasizes Dr. Markus Kuhr, Senior Manager for Technical Service Analytics at SCHOTT.
Photo: SCHOTT/C. Costard
Today, this progress extends deep into the depths of the nano cosmos and requires extremely high-power analytical tools because opening up unique product worlds that are modeled to the highest extent possible is driven by ever shorter development times and innovation cycles. ”These issues are becoming increasingly complex. We need extremely advanced equipment in order to be able to come up with answers more quickly and support our divisions more effectively,” explains Dr. Stephan Corvers, SCHOTT Technical Service Analytics.
High-precision microscope and tool
The electron beam optics and ion beam optics in the CrossBeam workstation Neon 40 with an SEM (Scanning Electron Microscope) and an FIB (Focused Ion Beam) allow for simultaneous observation and preparation of micro- and nano-structured samples. In this photograph, a protective coating is vapor deposited with the help of a gas injection system to allow for a defined amount of material to be removed inside the zone to be prepared (see micro photo to the right).
Conventional preparation methods that previously needed significantly more time or could not be done at all can now be executed and more quickly accomplished with the FIB in the Neon 40. Areas like development and damage analytics will benefit from this. For example, phosphate glasses that are connected to electroconductive glass-to-metal feedthroughs showed signs of deterioration after being stored in a refrigerator, despite the fact that a protective coating against humidity had been applied. Only FIB preparation of a cross section through the corroded surface caused nano scale defects in the layer. Humidity chewed its way through it and caused the glass to dissolve. ”These types of insights enable us to improve the structure, adhesion and chemical stability of the layer and ultimately the entire glass-to-metal compound. In addition, we are able to detect defects more accurately and more quickly for internal and external customers. We are able to answer questions such as, ,What caused the system to fail?, Now, we have just the right magnifying glass we need to do this type of detective work,” Dr. Kuhr notes.
The ion beam optics FIB (Focused Ion Beam) of the Neon 40 can often do very quickly what conventional preparation methods either can't do at all or take much longer to do. Photo: SCHOTT/C. Costard
In fact, this high-performance tool even sees things that SCHOTT could never see before. For example, the multicomponent nano structure of the cermet layer can now be displayed. This absorber layer absorbs the radiation from the sun in the receivers used in solar power plants. It contains extremely small metal particles that increase efficiency, but would be too small to be used for display purposes with the devices previously available. ”Now, we are able to optimize these particles and thus further increase the efficiency of the receiver,” Dr. Corvers explains. This instrument also provides more reliable results than other techniques because sometimes the sample has to be destroyed to allow for target preparation of extremely small defects. Small porous particles only 10 micrometers in size that initially only occur as colored points and lie under the surface of a glass or glass-ceramic are only one example. This type of defect is extremely difficult to detect. Grinding or polishing is usually either too risky or impossible. FIB characterization, however, increases the probability of deriving  useful analytical results. ”And the possibilities an electron microscope offers are far from being exhausted,” Dr. Kuhr notes. <