Month: November 2019

Those People and Things

Dr. Sophie Yan, Applications Engineer, EDAX

Click here to read the post in Chinese.

The end of the year is my conference season. I have been to various conferences since October and I have seen many new faces. Recently, I realized that several young people I trained have stepped into the electron microscopy and microanalysis world. Their reasons seemed to be similar: want a life like Sophie’s. I felt deeply honored but also frightened. Did I give the young people a good example or fantasy?

A couple of us who used to study and/or work at Shanghai Institute of Ceramics have organized an annual meetup at the Chinese Electron Microscopy Society Conference. This year the number of participants reached 19, indicating more and more people have joined this field. As time passes, I have been able to recognize some of the big names in microscopy, and I am overwhelmed at how quickly young scientists have become those big names. Indeed, when more and more new faces have become major players in this field, it indicates the prosperity of this field. I am very fortunate to be a witness of this booming industry.

Once at SEMICON, a participant from Taiwan couldn’t believe my decision to step out after he/she realized that I was no longer in the semiconductor industry. At that time, I didn’t care about his/her words, but right now I figured out why he/she felt so sorry for me. It is very fortunate to love a job you choose. The semiconductor industry was a little down at the time I left, but it has been developing incredibly fast afterwards and I have found the job I love. It is so good to see that my breakup with semiconductor made both of us happy.

Mr. Yang from The University of Science and Technology Beijing (the author of the first Chinese EBSD book you’re supposed to read in China) used to tell me that “I felt you have been attending a lot of conferences and got much more resources than other people.” So I really got lucky.

My EBSD mentor, European applications specialist, René de Kloe, has traveled all around the world. He is very knowledgeable and humble but shows his expertise when questioned. He always promptly and fully replies to my emails and is always ready to help. Although we meet often, every time I am impressed by his expertise and like him more.

Dr. Sophie Yan and Dr. Stuart Wright

Dr. Sophie Yan and Dr. Stuart Wright

EDAX EBSD experts at a meeting in Draper, UT.

EDAX EBSD experts at a meeting in Draper, UT.

And Dr. Stuart Wright, he is a legend in the EBSD world. His name appears in textbooks and references to all kinds of EBSD papers. He took René and I to the west coast of the United States the first time I met him. René said that his toes finally touched the water of the Pacific Ocean again and for the first time in 3 years. He said that his feet high fived each other from the last time he dipped his feet in Tokyo Bay. In 2017, ICOTOM was held in the small city where Stuart lives. As a conference organizer, he took care of everything by himself. That was the most successful conference that considered both academic atmosphere and hospitality. (Well, I must attend the next ICOTOM in Osaka in September 2020).

With lots of luck, I have been to many places and gotten in touch with big names in this field. The cost is I travel more than 50%, on mainly domestic trips with more than 100,000 kilometers every year. I have seen everything there is to see in the Beijing and Shanghai airports. In contrast, the streets of every city look common to me. A kind of common that you can’t figure out their meanings at a glance.

Beijing Daxing International Airport

The new Beijing Daxing International Airport opened in September 2019.

But when people ask what exactly is EDAX’s direct electron detection? I can finally calm down and keep the conversation going, although I just know a little about it. René and Stuart patiently explained it to me when I knew nothing about it, and now it is my turn to spread the word. This is a brand-new field, and EDAX is the first player. What can we do with direct electron detection? Just wait and see. For a sneak preview, take a look at René’s recent webinar, “Direct Electron Detection with Clarity™ – Viewing EBSD Patterns in a New Light”.

Look Closer

Dr. René de Kloe, Applications Specialist, EDAX

All our senses are aimed at observation. We feel, see, hear, smell and taste things to experience the world around us. We are relying on our senses to make many of our day-to-day decisions and choices. And especially in the upcoming holiday season, shops and companies in the business of selling things cleverly use shiny advertisements, brochures, fragrances, and unbeatable product descriptions to entice us to select their wares. All the time hoping that we will succumb to our senses that focus on the superficial appearance of products before thinking things through.

We must be very careful not to let this very successful marketing strategy subconsciously guide us when analyzing materials as well. During our work as microscopists we are continuously selecting samples, cutting and preparing them to expose a feature of interest, and then choosing the analytical tool and actual analysis area. How sure can we be that we really get representative and objective information?

Dr. René de Kloe's PhD thesis

Dr. René de Kloe’s PhD thesis.

As a geologist, I was taught to take your distance from a rock outcrop and look it over before going into any detail, knowing that the context of your observations is crucial in your interpretation. Then I would go in close to look, feel, and yes sometimes actually taste the rock in order to try to identify what I was actually looking at and how the overall structure fit in the geological setting of the area.

Observing this distance is crucial for your understanding of structures, but in some cases, you cannot get out far enough to see the bigger picture and then you must make do with what you can see.

Perhaps an extreme example is what I did for my PhD research. I have studied the occurrence and distribution of nm-scale films of amorphous material along grain boundaries in experimentally deformed rocks that originate deep inside the Earth. In total I may have characterized a few cubic microns of material but based on that I tried to draw conclusions on the effects of these melt layers on the movements of entire continents!

In microanalysis, we are suffering from the same problem. Microscopy inherently means that you cannot look at the wider picture and when you are looking at extremely small-scale features, their size combined with a practical image resolution may limit the observable surface even further. And one of the most difficult questions you then must ask yourself before starting an analysis is, if the analysis area is representative. And that can be a really tricky question. How objective are we all when browsing the sample surface to find a spot to collect the data? Don’t we all tend to preferentially pick an area that looks promising? I am not so sure that that would always be the most representative region.

It is not that long ago that the acquisition limits in EDS and EBSD were caused by the detector technology. For EDS mapping, we were quite happy if you could collect your data with 50,000 input counts per second and a 50% dead time. This meant that when you were collecting a 512 x 400 pixel map where you wanted to have, say 1000 X-ray counts per pixel, it would take you a few hours. And after that time someone else would be hovering behind you, eager to use the microscope. This seriously limited the sample area that could be analyzed and as a researcher you needed to think carefully about your analysis strategy to get representative information.

Single field EDS map of FeSi sample with REE phases

Single field EDS map of FeSi sample with REE phases.

The area that can be analyzed has changed dramatically with the introduction of the latest EDS detector technology. These detectors are capable of processing more than two million input counts and get maximum throughputs of 850,000 counts per second. You can now get the same area analysis in a matter of minutes, which allows you to analyse more samples or simply more areas on your sample. Alternatively, you can choose to get a wider view and collect large area mosaic maps to minimise the risk of unintended preferential area selection and get more representative data.

120 field multi-field EDS map of an igneous rock showing merged ROI maps of Si (red), Fe (yellow), and O (green) on a backscatter SEM image. Total image resolution 6144 x 4000 points ~ 5.4 x 3.5 mm

120 multi-field EDS map of an igneous rock showing merged ROI maps of Si (red), Fe (yellow), and O (green) on a backscatter SEM image. Total image resolution 6144 x 4000 points ~ 5.4 x 3.5 mm.

A similar dramatic improvement has occurred in EBSD technology. When I started as EBSD application specialist at EDAX in 2001, my first EBSD demo system could collect at least two points per second when it was not raining and the moon was in the right quarter (or perhaps more realistically, if I was really lucky to have a good sample with strong patterns). The map below was one of my first maps that I collected when getting to know the system and I still use it today as an example to show different typical EBSD mapping features, such as grain boundaries, subgrain boundaries, twins, and slip planes. This map contains “only” 124,405 points but took an 8.5-hour overnight scan to collect.

EBSD IPF on IQ map of Ni alloy

EBSD IPF on IQ map of Ni alloy.

 

49 field EBSD comboscan IPF on PRIAS™ center map of an Fe alloy

49 multi-field EBSD comboscan IPF on PRIAS™ center map of an Fe alloy.

The same map today would take less than half a minute to collect with a Velocity™ EBSD detector. Or when you would like to take a little wider view you can combine beam and stage movements to collect a 2.5 million point scan of an entire sample in about 15 minutes.

These technological improvements allow you to be more efficient with your time and collect the same data much faster. But alternatively, it can effectively open our eyes and allow us to investigate much larger areas to see the bigger picture. Just be careful when you look at things from a bit further away, sometimes at the end of the day it may seem that these things start looking back at you!

Large area EDS map of FeSi sample with REE phases – look who’s watching!

Large area EDS map of FeSi sample with REE phases – look who’s watching!