Author: edaxblog

How to Increase Your Materials Characterization Knowledge with EDAX

Sue Arnell, Marketing Communications Manager, EDAX

The EDAX Applications and Product Management teams have been very busy offering free ‘continuing education’ workshops in September and October – with a great global response from our partners and customers.

At the end of September, Applications Specialist Shawn Wallace and Electron Backscatter Diffraction (EBSD) Product Manager Matt Nowell joined 6 additional speakers at a ‘Short Lecture Workshop for EBSD’, sponsored by EDAX at the Center for Electron Microscopy and Analysis (CEMAS) at The Ohio State University. The participants attended sessions ranging from ‘EBSD Introduction and Optimization of Collection Parameters for Advanced Application’ to ‘The Dictionary Approach to EBSD: Advances in Highly-Deformed and Fine-Grained Materials’.

Feedback on this workshop included the following comments, “This was a great learning opportunity after working with my lab’s EDAX systems for a couple of months”; “I like the diversity in the public and the talks.  I was very pleased with the overall structure and outcome”; and “Great! Very helpful.”

Matt Nowell presents at the ‘Short Lecture Workshop for EBSD’ at CEMAS, OSU.

In mid-October, EBSD Applications Specialist, Dr. Rene de Kloe traveled to India for a series of workshops on EBSD at the Indian Institute of Science (Bangalore), the International Advanced Research Center (Hyderabad), and the Indian Institute of Technology (Mumbai). Topics discussed at the sessions included:

• Effects of measurement and processing parameters on EBSD
• The application of EBSD to routine material characterization
• Defining resolution in EBSD analysis
• Three Dimensional EBSD analysis – temporal and spatial
• Advanced data averaging tools for improved EDS and EBSD mapping – NPAR™
• Microstructural Imaging using an Electron Backscatter Diffraction Detector – PRIAS™
• Transmission EBSD from low to high resolution

Dr. René de Kloe presents at one of three recent workshops in India.

According to our National Sales Manager in India, Arjun Dalvi, “We conducted this seminar at different sites and I would like to share that the response from all our attendees was very good. They were all eager to get the training from Dr. René and to take part in very interactive Q and A sessions, in which many analysis issues were solved.”

Global Applications Manager Tara Nylese was at the Robert A. Pritzker Science Center in Chicago, IL last week to give a presentation on “Materials Characterization with Microscopy and Microanalysis” for the Illinois Institute of Technology. “In this lecture, we started with a basic introduction to electron microscopy, and then dived deeper into the fundamentals of X-ray microanalysis. We explored both the basics of X-ray excitation, and how to evaluate peaks in an X-ray spectrum. From there, we looked at applied examples such as composition variation in alloys, chemical mapping of components of pharmaceutical tablets, and some fascinating underlying elemental surprises in biological materials.”

Finally, today we have 50 participants at the Geological Museum in Cambridge, MA for a training workshop given by Dr. Jens Rafaelsen and sponsored by Harvard University on “Taking TEAM™ EDS Software to the Next Level” * Presentation topics include:

• Basic operation of the TEAM™ EDS Analysis package
• How to get the most out of TEAM™ EDS Analysis
• Advanced training
• Tips and Tricks using TEAM™ EDS Analysis

Dr. Jens Rafaelsen presents at the Harvard workshop.

Here at EDAX, we are keen to provide our customers, potential customers, and partners with opportunities to improve their knowledge and polish their skills using the techniques, which are central to the EDAX product portfolio.  Our EDS, EBSD, WDS and XRF experts are keen to help with regular training sessions, webinars, and workshops. If you would like to be included, please check for upcoming webinarsworkshops, and training sessions at www.edax.com.

*A video of these workshop sessions will be available from EDAX in the coming weeks.

My Fossil Background

Dr. René de Kloe, Applications Specialist, EDAX

Call me old-fashioned, but when I want to relax I always try to go outdoors, away from computers and electronic gadgets. So when I go on vacation with my family we look for quiet places where we can go hiking and if possible we visit places with interesting rocks that contain fossils. Last summer I spent my summer vacation with my family in the Hunsrück in Germany. The hills close to where we stayed consisted of shales. These are strongly laminated rocks that have been formed by heating and compaction of finegrained sediments, mostly clay, that have been deposited under water in a marine environment. These rocks are perfect for the occurrence of fossils. When an organism dies and falls on such a bed of clay and is covered by a successive stack of mud layers, it can be beautifully preserved. The small grains and airtight seal of the mud can give a very good preservation such that the shape of the plant or animal can be found millions of years later as a highly detailed fossil. Perhaps the most famous occurrence of such fossil-bearing shale is the Burgess shale in British Columbia, Canada which is renowned for the preservation of soft tissue of long-extinct creatures. The Hunsrück region in Germany may not be that spectacular, but it is a lot closer to home for me and here also beautiful fossils have been found.

Figure 1. Crinoid or sea lily fossil found in the  waste heap of the Marienstollen in Weiden, Germany.

Figure 2. Detail of sulphide crystals.

Figure 3. Example of a complete crinoid fossil (not from the Hunsrück area). Source https://commons.wikimedia.org/wiki/File:Fossile-seelilie.jpg

So, when we would go hiking during our stay we just had to pack a hammer in our backpack to see if we would be lucky enough to find something spectacular of our own. What we found were fragments of a sea lily or crinoid embedded in the rock (Figures 1,3) and as is typical for fossils from the area, much of the fossilised remains had been replaced by shiny sulphide crystals (Figure 2). Locally it is said that the sulphides are pyrite. FeS2. So of course, once back home I could not resist putting a small fragment of our find in the SEM to confirm the mineral using EDS and EBSD. The cross section that had broken off the fossil showed smooth fracture surfaces which looked promising for analysis (Figure 4). EDS was easy and quickly showed that the sulphide grains were not iron sulphide, but instead copper bearing chalcopyrite. Getting EBSD results was a bit trickier because although EBSD bands were often visible, shadows cast by the irregular surface confuse the band detection (Figure 5).

Figure 4. Cross section of shale with smooth sulphide grains along the fracture surface.

Figure 5. EBSD patterns collected from the fracture surface. Indexing was done after manual band selection. Surface irregularities are emphasized by the projected shadows.

Now the trick is getting these patterns indexed and here I do like computers doing the work for me. Of course, you can manually indicate the bands and get the orientations of individual patterns, but that will not be very helpful for a map. The problem with a fracture surface is that the substrate has a variable tilt with respect to the EBSD detector. Parts of the sample might be blocking the path to the EBSD detector which complicates the EBSD background processing.

The EDAX EBSD software has many functions to help you out of such tight spots when analyzing challenging samples. For example, in addition to the standard background subtraction that is applied to routine EBSD mapping there is a library of background processing routines available. These routines can be helpful if your specimen is not a “typical” flat, well-polished EBSD sample. This library allows you to create your own recipe of image processing routines to optimize the band detection on patterns with deviating intensity gradients or incomplete patterns due to shadowing.

The standard background polishing uses an averaged EBSD pattern of more than ~25 grains such that the individual bands are blended out. This produces a fixed intensity gradient that we use to remove the background from all the patterns in the analysis area. When the actual intensity gradient shifts due to surface irregularities it is not enough to just use such a fixed average background. In that case you will need to add a dynamic background calculation method to smooth out the resulting intensity variations.

This is illustrated in the EBSD mapping of the fossil in Figure 6. The first EBSD mapping of the fossil using standard background subtraction only showed those parts of the grains that happened to be close to the optimal orientation for normal EBSD. When the surface was pointing in another direction, the pattern intensity had shifted too much for successful indexing. Reindexing the map with optimised background processing tripled the indexable area on the fracture surface.

Figure 6. Analysis of the fracture surface in the fossil. -1- PRIAS center image showing the smooth sulphide grains, -2- Superimposed EDS maps of O(green), Al(blue), S(magenta), and Fe(orange) -3- EBSD IPF on IQ maps with standard background processing, -4- original IPF map, -5- EBSD IPF on IQ maps with optimized background processing, -6- IPF map with optimized background.

In addition to the pattern enhancements also the band detection itself can be tuned to look at specific areas of the patterns. Surface shadowing mainly obscures the bottom part of the pattern, so when you shift the focus of the band detection to the upper half of the pattern you can maximize the number of detected bands and minimize the disturbing effects of the edges of the shadowed area. It is unavoidable to pick up a false band or two when you have a shadow, but when there are still 7-9 correct bands detected as well, indexing is not a problem.

Figure 7. Band detection on shadowed EBSD pattern. Band detection in the Hough transform is focused at the upper half of the pattern to allow detection of sufficient number of bands for correct indexing.

In the images below are a few suggestions of background processing recipes that can be useful for a variety of applications.

Of course, you can also create your own recipe of image processing options such that perhaps you will be able to extract some previously unrecognized details from your materials.

A Bit of Background Information

Dr. Jens Rafaelsen, Applications Engineer, EDAX

Any EDS spectrum will have two distinct components; the characteristic peaks that originate from transitions between the states of the atoms in the sample and the background (Bremsstrahlung) which comes from continuum radiation emitted from electrons being slowed down as they move through the sample. The figure below shows a carbon coated galena sample (PbS) where the background is below the dark blue line while the characteristic peaks are above.

Carbon coated galena sample (PbS) where the bacground is below the dark blue line while the characteristic peaks are above.

Some people consider the background an artefact and something to be removed from the spectrum (either through electronics filtering or by subtracting it) but in the TEAM™ software we apply a model based on Kramer’s law that looks as follows:Formulawhere E is the photon energy, N(E) the number of photons, ε(E) the detector efficiency, A(E) the sample self-absorption, E0 the incident beam energy, and a, b, c are fit parameters¹.

This means that the background is tied to the sample composition and detector characteristic and that you can actually use the background shape and fit/misfit as a troubleshooting tool. Often if you have a bad background, it’s because the sample doesn’t meet the model requirements or the data fed to the model is incorrect. The example below shows the galena spectrum where the model has been fed two different tilt conditions and an overshoot of the background can easily be seen with the incorrect 45 degrees tilt. So, if the background is off in the low energy range, it could be an indication that the surface the spectrum came from was tilted, in which case the quant model will lose accuracy (unless it’s fed the correct tilt value).


This of course means that if your background is off, you can easily spend a long time figuring out what went wrong and why, although it often doesn’t matter too much. To get rid of this complexity we have included a different approach in our APEX™ software that is meant for the entry level user. Instead of doing a full model calculation we apply a Statistics-sensitive Non-linear Iterative Peak-clipping (SNIP) routine². This means that you will always get a good background fit though you lose some of the additional information you get from the Bremsstrahlung model. The images below show part of the difference where the full model includes the steps in the background caused by sample self-absorption while the SNIP filter returns a flat background.

So, which one is better? Well, it depends on where the question is coming from. As a scientist, I would always choose a model where the individual components can be addressed individually and if something looks strange, there will be a physical reason for it. But I also understand that a lot of people are not interested in the details and “just want something that works”. Both the Bremsstrahlung model and the SNIP filter will produce good results as shown in the table below that compares the quantification numbers from the galena sample.

Table

While there’s a slight difference between the two models, the variation is well within what is expected based on statistics and especially considering that the sample is a bit oxidized (as can be seen from the oxygen peak in the spectrum). But the complexity of the SNIP background is significantly reduced relative to the full model and there’s no user input, making it the better choice for the novice analyst of infrequent user.

¹ F. Eggert, Microchim Acta 155, 129–136 (2006), DOI 10.1007/s00604-006-0530-0
² C.G. RYAN et al, Nuclear Instruments and Methods in Physics Research 934 (1988) 396-402

Thoughts from a Summer Intern

Kylie Simpson, Summer Intern 2017, EDAX

This summer at EDAX, I have had the opportunity not only to build upon the skills that I acquired here last summer and throughout my academic year, but also to acquire new skills enabling me to better understand energy dispersive spectroscopy (EDS), materials science, and applied physics. Having access to state-of-the-art microscopes, detectors, and literature has certainly played a large role in my take-away from this summer, but the most valuable aspect of my time at EDAX is the expertise of those around me. Working with the applications team provided me with the opportunity to work alongside the different groups, including the engineering, sales and marketing, and technical support groups, as well as with customers via demos, training courses, and webinars. Not to mention the plethora of knowledge within the applications team itself. The willingness of other EDAX employees not only to help me, but also to explain and teach me how to solve the problems I encountered was extremely helpful.

The major projects I worked on this summer were compiling a user manual for the EDAX APEX™ software, collecting data for a steel library, and tuning a PID system for the thermoelectric cooler used in EDAX detectors. Creating a user manual for APEX™ enabled me to fully understand the software and describe it in a clear and useful way for our customers. I used LaTeX™ software to compile the manual, which exposed me to a very powerful typesetting tool while optimizing the layout and accessibility of the manual. Because I was not involved in the design of APEX™, I was able to write the user manual from the perspective of a new user. As a student and a newer user of EDAX software, I have recognized how useful APEX™ is for beginners and hope that the user manual will help to complement its value.

The EDAX APEX™ User Manual.

Figure 1: The EDAX APEX™ User Manual.

The steel library project that I worked on was very interesting because I compiled data that will simplify and aid customers working with steel samples. I collected spectra for nearly 100 steel standards and compared the quant results to the known values to confirm the accuracy of the data. This data will soon be available for purchase by customers who would like to compare the spectra from unknown samples to those of known standards using the spectrum match feature.

Me using one of our scopes to collect data.

Figure 2: Me using one of our scopes to collect data.

Additionally, I was able to work with the engineering team to tune a PID system for the thermoelectric cooler inside all EDAX detectors. The module of each detector must reach a set point temperature in a set period of time and remain stable. By making small changes to the parameters and determining their impact, I ran tests over several weeks to optimize the cooling of the detector. These parameters will be used in future development of EDAX detectors, enabling them to work even more accurately.

Figure 3: The PID system I worked with and me.

Overall, my experience at EDAX has been very positive, providing me with the skills and knowledge to succeed and excel in both academics and my career.

What Kind of Leaves Are These?

Dr. Bruce Scruggs, XRF Product Manager, EDAX

This year is shaping up to be an interesting year for travel. Five countries and counting, and I’m not even including a stopover in Texas. The last trip was to Brazil. Beautiful country. But, there’s a reason you see snack and beverage vendors roaming the side of the highways in Rio and Sao Paulo..…

I started out with a micro-XRF workshop at the Center for Mineral Technology at the Federal University at Rio de Janeiro. We were working out of the Gemological Research Laboratory with Dr. Jurgen Schnellrath. At the end of the technical presentations, we analyzed some various pieces of jewelry that participants from the workshop brought. I must admit that this makes me a bit nervous to analyze anything with unforeseen sentimental value and I refuse to analyze engagement and wedding rings. A large pair of blue sapphire earrings turned out to be glass. (Purchased at a garage sale at a garage sale price. So, no big surprise …) Another smaller set of blue sapphire earrings were found to be natural sapphires accompanied by a sigh of relief from the owner. (They came from a reputable jewelry shop with a reputable jewelry shop price.)

Gold leaf “Gold leaf'” embedded in resin

At the end, we analyzed what was termed “gold leaf” jewelry, i.e. a ring and a pair of earrings. The style of these pieces was thin gold leaf foil embedded in resin. The owner was one of the younger students in the lab and she had purchased the jewelry herself from a relatively well-known designer’s collection. The goal was to measure for the presence of gold. Since the gold leaf was embedded in resin, XRF was the ideal tool to measure the pieces non-destructively. The jewelry also had some rather odd topography at times given the surrounding resin, but the Orbis had no problem to target the gold leaf given the co-axial geometry of the exciting X-ray and video imaging. I would have liked to have used the excuse that we couldn’t target the sample accurately because of XRF system geometry. There was no gold. Copper / Zinc alloy. That was it. She had paid about $30 US for the earrings and she said she felt cheated. I kept thinking “Cheated? Maybe … live a little, wait until you buy a house!” Later, I was searching the internet looking for a technical definition for “gold leaf”. I knew I was onto something when I found a webpage that said that gold leaf was “traditionally” 22K gold thin foil used for gilding. The page later described modern Copper/Zinc alloy metal leaf “… offering the same rich look of gold leaf, but at a fraction of the price….” Apparently, this metal leaf can be found at art stores. Who knew?

From there, we went on to the state of Sao Paulo and did a workshop at the Center for Nuclear Energy in Agriculture at the University of Sao Paulo. During the workshop, some of the students gave presentations on their work. I saw a very interesting experimental setup with live plants being measured in the Orbis. The plant’s roots were placed in a water bath doped with various forms of minerals or fertilizers. The whole plant, roots, stem, leaves, was then inserted into the Orbis and the stem was measured to monitor the uptake time for the relevant components in the bath. The plants could be moved in and out of the chamber to monitor the uptake over extended periods of time and over various portions of the plant.

On the way to the Sao Paulo airport, I had the pleasure of sitting in the longest traffic jam I have ever endured with the monotony being broken by roaming snack and beverage vendors. It was quite the sight to watch the peanut vendors carrying propane fueled peanut warmers traversing the lane dividers on the highway with the occasional motorcycle speeding between the cars along the same lane dividers.
Tip for next time … buy the Brazilian produced chocolate before going to the airport. The selection at the airport is rather limited and you never know when you may be having more fun than humans should be allowed to have watching motorcycles and peanut hawkers.

What an Eclipse can teach us about our EDS Detectors

Shawn Wallace, Applications Engineer, EDAX

A large portion of the US today saw a real-world teaching moment about something microanalysts think about every day.

Figure 1. Total solar eclipse - image from nasa.gov

Figure 1. Total solar eclipse.                                  Image credit-nasa.gov

With today’s Solar Eclipse, you could see two objects that have the same solid angle in the sky, assuming you are in the path of totality. Which is bigger, the Sun or the Moon? We all know that the Sun is bigger, its radius is nearly 400x that of the moon.

Figure 2. How it works.                                             Image credit – nasa.gov

Luckily for us nerds, it is also 400x further away from the Earth than the moon is. This is what makes the solid angle of both objects the same, so that from the perspective of viewers from the Earth, they take up the same area in the sphere of the sky.

The EDAX team observes the solar eclipse in NJ, without looking at the sun!

Why does all this matter for a microanalyst? We always want to get the most out of our detectors and that means maximizing the solid angle. To maximize it, you really have two parameters to play with: how big the detector is and how close the detector is to the sample. ‘How big is the detector’ is easy to play with. Bigger is better, right? Not always, as the bigger it gets, the more you start running in to challenges with pushing charge around that can lead to issues like incomplete charge collection, ballistic deficits, and other problems that many people never think about.

All these factors tend to lead to lower resolution spectra and worse performance at fast pulse processing times.
What about getting closer? Often, we aim for a take-off angle of 350 and want to ensure that the detector does not protrude below the pole piece to avoid hitting the sample. On different microscopes, this can put severe restrictions on how and where the detector can be mounted and we can end up with the situation where we need to move a large detector further back to make it fit within the constraining parameters. So, getting closer isn’t always an option and sometimes going bigger means moving further back.

Figure 3. Schematic showing different detector sizes with the same solid angle. The detector size can govern the distance from the sample.

In the end, bigger is not always better. When looking at EDS systems, you have to compare the geometry just as much as anything else. The events happening today remind of us that. Sure the Sun is bigger than Moon, but the latter does just as good a job of making a part of the sky dark as the Sun does making it bright.

For more information on optimizing your analysis with EDS and EBSD, see our webinar, ‘Why Microanalysis Performance Matters’.

EDAX China User Meeting in Guiyang 贵阳用户会流水帐

Dr. Sophie Yan, Applications Engineer China, EDAX

EDAX China User Meeting, Guiyang.

EDAX China User Meeting, Guiyang.

EDAX held a China user meeting in Guiyang, Guizhou province in July 2017. We had a wonderful time with over 100 customers and colleagues. The User Meeting was very interesting; the weather is cool in summer; and the activities after the meeting were great fun.. I have several pictures to show the different moments…
Generally, Guiyang is not very popular with Chinese people. In Shanghai, there are luxuries in Huaihai Road and crowds in Nanjing Road; in Beijing, you find the solemn Tiananmen Square and desolate The Great Wall, but in Guiyang, I just had an impression of a poverty-stricken mountain area. Then I met a friend from Guiyang, she also talked about poverty and the mountain area, but she was much more enthusiastic about the region. She said it was warm in winter and cool in summer; she said the mountain and water were so nice. She was a stylish girl, living an exquisite life; but she always wished she could go back to hometown earlier. From then on, Guiyang became a kind of mystery in my mind.
其实我对贵阳思慕已久。
上海上海,是淮海路的名牌南京路的热闹;北京北京,是天安门的庄严长城的苍凉。贵阳,有什么?大山的贫瘠与封闭?直到当年,我碰到一位朋友,来自贵阳。她也说起大山及贫穷,但是她的话里,那里冬暖夏凉,水暖山温。那位朋友,思想前卫,生活精致,心心念念的,却是早日回家。至此,贵阳,在我心里是颇为神秘的所在。
After so many years, when I arrived in Guiyang, the feeling of mystery and novelty disappeared. The airport looks great and the billboard is modern and impressive. It was no different from other places, except that it’s 10 degrees cooler than Shanghai. I shared this image in ‘wechat’ moments, then got a lot of ’likes’.
一念多年。当踏上这个城市的土地,我所以为的一切,新奇,神秘,通通颠覆。这里的机场不小,广告牌也一派摩登气派。和我去过的地方并无多大不同。除了,比起火炉一般的江浙沪低了十度,发在微信朋友圈,引起一片哀号。看看这一张截图,就拉了多少仇恨。

During the conference our VP Mark Grey came and delivered a corporate introduction. Nan Lin from Singapore and local applications showed new product information: EDS, EBSD, XRF, etc.
开会中……VP Mark过来作公司简介,新加坡的林楠以及国内的应用分别作产品介绍……EDS,EBSD,XRF,嗯,分工明确。

Invited speakers shared their research work in the afternoon. Each one generated lively discussion. The EDAX user meeting is not only an opportunity to show EDAX products, it is also a platform for users’ to communicate with each other and discuss current challenges in microanalysis.
下午各位嘉宾给大家作邀请报告……每个报告都引起了热烈的反应,讨论得不亦乐乎……EDAX的用户会不单是一个产品展示的环节,更是一个用户交流的平台……

Speakers at the China User Meeting 2017

Speakers at the China User Meeting 2017

Imagine the scenery outside. The weather forecast showed 29 degree(Celsius), but it was cool actually. Green trees and a humid atmosphere made the sultry summer go away.
开会中间例行出来拍照,当时天气预报29度,但是风吹得非常凉爽。分明才是初夏的温度,凉风习习的感觉。加上四周绿树葱茏,空气中的润泽气息,盛夏的酷热,早已远离。

 
The hotel located beside Guanshanhu Park, which was gorgeous.
酒店在观山湖公园旁边,风景如画(图片来自百度,笔者拍照无能……)
No one was in this corner of the park. Red flowers were quietly in bloom.
傍晚的公园角落寂寂无人,一丛红花在碎石小径上静静盛开。

We went to Huangguoshu waterfall! The white waterfall poured down. I felt the vapor and steam: it was amazing.
当然这次贵阳之行的精妙处不止于此……还有我最为盼望的——黄果树瀑布!如匹练的白色倾泻直下,瀑布脚下水汽氤氲,在近处感受那赫赫声势,大自然的鬼斧神工,实非人力所能及。
Just behind the hill, the water from the waterfall formed a lake, gentle and quiet.
瀑布积水成湖,湖水温柔静谧。水的另一面。

We also experienced the different culture of the local ethnic minority. Terraced fields, bamboo buildings,songs and dance from local people. Attractive.
我们还顺便见识了少数民族的多样文化。梯田,依山而建的竹楼,以及多姿多彩的歌舞。不虚此行。

Finally, we are looking forward to the next user meeting in China!
流水帐完结处,唯愿年年有今日,岁岁有今朝!