Introducing the new DENSsolutions In Situ TKD Stage

Introducing the new DENSsolutions In Situ TKD Stage

by | Nov 25, 2020 | Interview

An interview with Product Manager Dr. Gin Pivak about our latest In Situ TKD Stage

DENSsolutions introduces its latest solution for electron microscopy: the In Situ TKD Stage. This stage allows you to perform high resolution microstructural characterization inside your SEM using Transmission Kikuchi Diffraction (TKD) while heating or biasing your sample. We interviewed our Product Manager Dr. Gin Pivak to learn all about the stage, from the reason behind its development to its innovative capabilities. 

Why was this In Situ TKD Stage designed?

The electron backscatter diffraction method (EBSD) has been widely used to study crystal orientation, phase identification and grain size distribution in steels and other types of materials. However, the resolution of the EBSD technique is limited at best to 20 nm, allowing you to characterize polycrystalline materials down to about 100 nm in grain size. To attain a higher resolution, users must resort to transmission electron microscopes (TEM), 4D STEM and/or converging beam electron diffraction (CBED) methods, which are much less accessible.

The TKD method, on the other hand, enables orientation maps of electron transparent samples and allows you to quantitatively map changes in crystal orientation or structure in nanocrystalline materials. Moreover, the TKD experiment can be performed in a SEM, making the technique considerably more accessible with a shorter set-up time and lower cost of entry compared to that of TEM.

DENSsolutions realizes the challenges users are facing in regards to technical limitations, accessibility, time and costs. The In Situ TKD stage was therefore developed, enabling in situ studies of grain distribution and orientation maps of fine-grained and heavily deformed materials. It allows you to have a high spatial resolution similar to that of a TEM but without its impediments. The in situ TKD stage can be used in various applications fields such as automotive, aerospace, electronics, and power generation where in situ heating and/or biasing can help to understand and improve the properties of materials and devices.

What are the main benefits of the In Situ TKD Stage?

One of the most important benefits that the TKD Stage offers is saving you valuable time on the TEM, as you can perform quick preliminary in situ sample characterization inside the SEM instead. Moreover, with the TKD Stage you can conduct in situ heating and/or biasing experiments inside the SEM, making it considerably more accessible for users who are unable to access a TEM. Furthermore, as a result of its unique geometry, the In Situ TKD Stage allows you to perform microstructural characterization using the TKD method with high spatial resolution and simplified grain orientation mapping. 

The stage also allows you to easily interchange your chips as it is fully compatible with all double-tilt Wildfire and Lightning chips. Because of this, you are able to reach the exact same temperatures, voltages and currents inside the SEM as you can inside the TEM while easily swapping chips between microscopes.

Another important feature of the In Situ TKD Stage is the uniform workflow it offers. Because both the TKD Stage and our In Situ TEM solutions operate with the same stimuli supply components and control software, existing customers can easily integrate the TKD stage into their workflow.

What is the compatibility of the In Situ TKD Stage?

The TKD stage is compatible with different brands of SEM/FIBs, namely JEOL, Thermo Fisher Scientific (FEI) and Zeiss. It is also compatible with EBSD detectors from different companies, namely Bruker and Oxford Instruments. We are also looking into the possibility of expanding the compatibility of the stage to more brands. If you are using a different SEM or EBSD detector than the ones listed above, please do not hesitate to contact us.

Who are the people that will benefit from it?

There are a few types of users who will benefit from the TKD stage. This includes users who are interested in analyzing the grains structure and crystal orientation of samples under in situ heating and/or biasing stimuli. For others, the interest lies in the ability to conduct in situ heating and biasing experiments without so much focus on the orientation maps. For these users, the TKD Stage can be used as a simple in situ SEM stage that is more time and cost effective compared to that of a TEM for performing dynamic experiments.

What kind of challenges were tackled during development?

One of the greatest challenges we faced when developing the In Situ TKD Stage was ensuring the widest compatibility without sacrificing its performance. Moreover, we spent a long time on ensuring the flexibility and user-friendliness of the stage. We wanted the TKD Stage installation to be straightforward and effortless, but also flexible to change the orientation of the chips/samples. We also focused on ensuring that the working would be swiftly reached, and that the Nano-Chip positioning inside the TKD stage would be easy.

Another challenge was making the stage compatible with our Wildfire and Lightning Nano-Chips. We wanted to make sure that this was possible so that our Wildfire and Lightning customers could simply purchase the TKD stage and reuse their existing chips and heating/biasing control hardware and software.

Despite these challenges, we managed to fulfil all critical requirements and more. The stage is exceptionally easy to operate, installation takes no more than 10 minutes (even including replacing a flange for a vacuum electrical feedthrough) and the operating vacuum can be reached immediately after the installation within 10 minutes.

Did we cooperate with customers on this development?

Our policy at DENSsolutions has always and will always be to involve users when developing new products. We believe that it is simply impossible to create exceptional products without customers’ involvement.

Following our approach, we involved Vijay Bhatia from University of Sydney during the development of the In Situ TKD Stage. He informed us of necessary requirements for the stage from an experimental point of view, allowing us to design as optimally as possible.  

Which future developments lie ahead?

We will continue to work on the user-friendliness of the TKD stage and its compatibility. Particularly, we will focus on the implementation of an automatic electrical connection of the TKD stage with the control hardware outside the SEM/FIB. Additionally, we will make it possible to integrate our control software into the EBSD/TKD software. This will allow you to sync the crystallographic and in situ stimuli data, simplify the analysis and even control the in situ TKD stage directly from the SEM/FIB software.

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Scientists find an alternate route towards CO2 reduction

Scientists find an alternate route towards CO2 reduction

by | Nov 24, 2020 | Catalyst research, Climate

In situ ETEM uncovers that deep-ultraviolet plasmons have the ability to drive endothermic reactions at room temperature

Original article by Canhui Wang, Wei-Chang D. Yang, David Raciti, Alina Bruma, Ronald Marx, Amit Agrawal and Renu Sharma

Plasmonic nanoparticles of certain metals, like gold, silver and aluminium, have the unique capability of harvesting and scattering light. These nanoparticles can harvest energy from a light source and transfer it to adsorbed gas molecules, ultimately reducing the temperature needed to drive the chemical reaction. Most of the reactions reported in research are exothermic, and only H-D bond formation has been successful at room temperature. However, for the first time in research, scientists from the NIST and IREAP in Maryland, U.S., find that endothermic reactions can be achieved at room temperature using localized surface plasmons (LSP) in the deep-UV range. Without the DENSsolutions Climate Air in situ system, this revolutionary finding would be awaiting its indispensable discovery. 

 

The DENSsolutions Climate system

When light excites the conduction electrons of certain metallic nanoparticles, it causes these electrons to undergo oscillation, generating localized surface plasmons (LSP). This resonant oscillation, called surface plasmon resonance (SPR), is essentially why these plasmonic nanoparticles have this exceptional ability to absorb and scatter light. 

In this in situ experiment, the reduction of CO₂ on a graphite sample to CO was realized at room temperature by exciting multiple LSP modes of aluminum nanoparticles using high-energy electrons. An ETEM is used to excite and characterize the aluminum LSP resonances and concurrently measure the spatial distribution of the carbon gasification around the nanoparticles in a CO₂ environment. Although this experiment took place in an ETEM, the ETEM was only used to provide an electron beam to generate the localized surface plasmons. It was the Climate Sample Holder that enabled the introduction of the CO₂ gas towards the sample.

In order to detect CO as a reaction product, the Climate Sample Holder containing the Climate Nano-Reactor was coupled to a gas chromatograph-mass spectrometer (GCMS). Four nanoreactor environments were analyzed, represented by the lines in the figure below: 1) Pure CO₂, 2) 0.01% CO added to the CO₂ gas flow, 3) Pure graphite heated at 900°C without aluminum nanoparticles, and finally 4) Illumination of aluminum on graphite in CO₂ at room temperature using an e-beam.

Detection of CO as a reaction product using the GCMS

Measurable CO was detected only in the latter three cases but not in pure CO₂. However, it was particularly in the last case where a CO-peak was realized when the electron beam was switched on to generate LSPs. Typically, a standard ETEM will produce CO concentrations that are far below the detection threshold of the GCMS. Yet, because the Climate Nano-Reactor in the Climate Sample Holder has a small volume, high pressure environment, the CO concentration in the CO₂ gas could rise high enough to enable the GCMS to detect it. This experiment demonstrates the unique stability and integrity of the Climate Nano-reactor over long periods of time. 

Novelty in findings

This novel finding not contributes highly on an academic front, paving the way for scientists to explore other industrially relevant chemical processes initiated by plasmonic fields at room temperature, but also globally by providing an alternate route for CO₂ reduction. Aluminium, Earth’s most abundant metal, presents itself as an ideal candidate for channelling energy from light to perform large-scale CO₂ reduction. This common and inexpensive metal therefore has ample potential to aid in the relentless fight against climate change.

Dr. Mihaela Albu

“The Climate Nano-Reactor proved to be essential for taking the reaction product of this LSP experiment out of the ETEM specimen chamber. Due to its unique low-volume, high-pressure design, the CO concentration in the carrier gas was still high enough to be detected ex situ.”

Ronald Marx
Senior Technical Consultant | DENSsolutions

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Achieving mass transport control with the award-winning Stream system

Achieving mass transport control with the award-winning Stream system

by | Nov 19, 2020 | Electrochemistry, LPTEM, Stream

The on-chip flow channel of the Stream system allows for full control over pressure, flow rate, liquid thickness and electric potential

Original article by Anne France Beker, Hongyu Sun, Mathilde Lemang, Tijn van Omme, Ronald G. Spruit, Marien Bremmer, Shibabrata Basak and  H. Hugo Pérez Garza

The liquid phase transmission electron microscopy (LPTEM) community faces numerous challenges when performing in situ electrochemical studies inside the TEM. From a lack of control over the flow and liquid thickness, to limited experimental flexibility and reproducibility, these challenges have posed considerable limitations on research. As a result, DENSsolutions has developed an in situ LPTEM solution that addresses each and every one of these challenges – the Stream system. Due to its unique on-chip flow channel design, users can effectively control experimental conditions such as pressure, flow rate, liquid thickness, electrical potential and bubbles. STEM videos are shown below to demonstrate these advantages and visualize the in situ growth of copper with multiple morphologies.

Because you can independently control the pressure at the inlet and outlet of the Stream Nano-Cell, you can control the absolute pressure in the microfluidic channel. This state-of-the-art design consequently gives you full control over the flow and the bulging of the windows, and therefore the liquid thickness. As a result, spatial resolution is improved, enabling meaningful electron diffraction and elemental mapping in liquid. You can accurately define the mass transport and control the electric potential, granting you complete access to the full kinetics of the reaction.

The in situ LPEM study

In order to exhibit the benefits of the system, copper dendrites were grown and characterized in situ. After the electrodeposition of the copper, EELS and EDS characterization were performed with copper inside the viewing area. Furthermore, high resolution images and diffraction patterns of the grown copper dendrites were recorded using the TEM.

Removal of beam-induced species

A major issue when performing LPTEM experiments with an electrolyte is the undesired influence of the electron beam. In this experiment, the electron beam interacts with the copper electrolyte. However, because you can control the flow of the liquid, you can remove or flush away any unwanted beam-induced species from the region of interest (i.e. window, sample or electrodes). This is displayed in the STEM recording below with the flow moving from right to left.

STEM movie showing debris being flushed

Bubble dissolution

It is important in LPTEM to assure that the cell stays wet. However, when bubbles form, the cell starts to dry out. The Stream system was developed with this in mind, offering a solution to this challenge. Specifically, because you can control the absolute pressure in the microfluidic channel, you can remove unwanted gas bubbles by setting the pressure high. At higher pressures, the size of the bubble decreases until it disappears and vice versa. The dissolution of a bubble that was formed during this copper experiment is shown in the STEM video below.

STEM movie showing bubble dissolution

In situ growth of copper dendrites

The growth and stripping of copper was completed a few times via cyclic voltammetry. The cycles begin with copper reduction, corresponding to the growth of the copper dendrites. Next, oxidation takes place, corresponding to the copper dendrites being stripped. Interestingly, you can see in the STEM video below that after reduction, the dendrites are thicker whereas after oxidation, the dendrites become much thinner.

STEM movie showing 5 cycles of copper growth and etching

Liquid thickness control 

In order to perform high resolution imaging, it is important in LPTEM that the liquid thickness is kept low. Aside from high resolution imaging, controlling the liquid thickness is extremely important when performing analytical techniques like EDS, EELS and electron diffraction. Ideally, the liquid should be limited below the beam broadening, which is normally expected to happen around 500nm of liquid thickness. With this in mind, we designed our Nano-Cell such that the thickness stays below the beam broadening threshold based on the spacer thickness and the maximum bulging of the windows. In the figures below, the elemental mapping and electron diffraction of the electrodeposited copper are presented. 

Elemental mapping - Anne article

EDX elemental mapping showing the spatial distribution of b) the copper dendrites and c) the platinum electrode 

Electron diffraction Annette article

TEM image of the copper dendrites on the electrode in e) and the corresponding SAED patterns in liquid phase in f)

Complete flow control

Controlling the flow also has other important advantages that are expanding possibilities in research. Namely, the ability to manipulate the flow rate allows you to control the morphology. You can see in the STEM image below that when flow is applied, the copper grows in a continuous layer with more copper being deposited. On the other hand, without flow, the copper nuclei grow isolated. This is direct proof that the unique flow-control feature of the system allows you to control the kinetics of an electrochemical reaction.

Morphology of copper with and without flow using the Stream system

Conclusively, this research highlights the unique capabilities of the award-winning Stream system, proving its potential to enable and boost research in various application fields, ranging from battery research and fuel-cells to corrosion and electrocatalysis.

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