Many thanks to Dr. David Tavakoli, XRD Facilities Manager at Georgia Tech’s IEN/IMAT Materials Characterization Facility (MCF), and Christa Ernst, Marketing Manager at Georgia Tech’s Institute for Electronics and Nanotechnology (IEN). The collaboration for this article with Malvern Panalytical does not constitute an endorsement by Georgia Tech.
The core facility for materials analysis at Georgia Tech is the IEN/IMat Materials Characterization Facility (MCF). The MCF is available to academic, industry and government users; it merges several labs on Georgia Tech’s campus and offers a variety of microscopy and characterization tools as well as skilled research staff to support research needs. Offering 24-hour a day shared-user access to the latest in imaging and analysis technology, and operated on a fee rate schedule, the MCF facility provides services for researchers including equipment training, remote sample prep and measurement, and imaging and analysis consultations.
MCF also happens to be where this top public research university and institute of technology houses their Malvern Panalytical Empyrean X-ray diffraction (XRD) instrument. The Empyrean XRD system generates X-rays, directs them toward a sample, and collects diffracted rays (the angle between the incident and the diffracted beam). Collected data are widely used for the identification of unknown crystalline materials (e.g. minerals, inorganic compounds), quantification of crystalline and amorphous materials, thin film thickness and structure, and many more applications. These applications are critical to studies in geology, environmental science, material science, engineering and biology.
The Empyrean lives a busy life in this facility, and is used around the clock for teaching, research and various application uses. What’s in a day in the life of an Empyrean XRD system at Georgia Tech? We break it down here, capturing the day of April 1, 2019:
Morning – Early Afternoon
Neha Kondekar, 4th year PhD student in Georgia Tech’s School of Materials Science and Engineering (MSE), begins the day working on the Empyrean system. Neha is studying MoS2 (Molybdenum disulfide) and phase transformations in two dimensional, or single layered transition metal dichalcogenides; she makes thin films of these materials – often less than 10 atoms thick. Use of the Empyrean XRD system allows Neha to obtain crystallographic information of this material and how it changes with the addition of different metal atoms like Cu, Ni and Fe. The metal atoms enter the MoS2 lattice in a certain ordered manner and the XRD system enables Neha to understand that arrangement. The applications of these novel materials are several, ranging from making thinner, smaller and faster transistors that power our electronic devices to catalysts that can produce hydrogen as a clean fuel.
Accompanying Neha working on the Empyrean system today is post-doc Pravlav Shetty. Neha and Pralav are using the system’s tilt-capable 3-axes cradle (chi, phi, Z), as they are working with thin films grown/deposited on substrates and need extremely accurate sample positionings.
Overall, the Empyrean is used heavily in the lab with a majority of the users using the 3-axes cradle (chi, phi, Z) and the Reflection-transmission spinner sample stages. Not used this day was MCF’s Empyrean non-ambient sample stage for high temperature (HTK 1200N) and the SAXS configuration, though both are used multiple times a month as well.
Specified Empyrean optics and detectors generally used on this Georgia Tech Empyrean system is mostly the Bragg-BretanoHD (BBHD) incident beam PreFIX module (90%). As well, the 2xGe Hybrid Monochromator incident beam PreFIX module is used for some applications. Additionally, the PIXcel3D area detector is used for most lab work, but is usually employed as a 1D detector.
The Materials Characterization (MSE 2021) undergraduate class, taught by Dr. David Tavakoli, shuffles into the MCF to occupy it from 3-6pm. This is the second week of this foundation class, offered to MSE majors and minors; the class introduces several techniques, including XRD. The XRD lab portion is two weeks long with the first week focused on single phase data collection and analysis. Sample preparation was discussed lightly in the first week, with the focus on how the instrument is set-up with the various optics (anti-scatter slits, masks, divergent slits), and a heavy discussion on how data analysis of a single-phase powder is performed.
Week two is the multi-phase section of this MSE 2021 undergraduate class; in this week’s lab, the students are running and analyzing an unknown multi-phase powder, with the students tasked with performing data analysis to determine unknown components. Dr. Tavakoli teaches the students how powder samples are handled on the Empyrean XRD system, with the importance of making sure that their samples are well-blended, homogeneous (as much as possible), and finely packed into the powder holders. The students then each practice by creating their own blend of powders and then running them on the Empyrean via the ambient reflection-transmission spinner sample stage.
After the undergraduate class completes, Xenia Wirth, 6th year PhD student in the Geosystems Engineering Program in Georgia Tech’s School of Civil and Environmental Engineering sets up to work in MCF’s preparation lab, to prepare her samples to run on the Empyrean overnight. She is researching the beneficial use of coal and biomass combustion residuals and studies the crystalline and amorphous composition of biomass and weathered coal fly ashes (powder samples). The Empyrean XRD system has helped Xenia quantify amorphous content, which is useful for determining if fly ash is pozzolanic enough (i.e. capable of binding calcium hydroxide in the presence of water) to be used in concrete applications. She has also used the Empyrean system to show how biomass fly ash differs compositionally as compared to coal fly ash, and to see if weathered coal has different crystalline phases than unweathered dry coal.
The Empyrean has an autosampler feature that works with the system’s reflection-transmission spinner; it can hold up to fifteen samples per magazine – and up to 3 magazines per system for a total of 45 samples – and is ideal for users that have a lot of samples to run. The Geosystems Engineering group was one of the first to really take advantage of the autosampler, and Xenia will frequently load her powder samples in the evening and have them run overnight. Other members of her group have also taken advantage of the autosampler feature, running multi-day time series where they watch their samples hydrolyze over multiple days.
Empyrean – The intelligent diffractometer
The Empyrean diffractometer performs a variety of XRD measurements on any type of polycrystalline material including inorganic, organometallic and organic substances. A variety of holders and stages can analyze powders, thin films, solid objects, and nanomaterials. As shown through this example of one day in Georgia Tech’s MCF facility, the Empyrean system is a true multipurpose platform designed to support a wide range of applications, and it can be easily configured by each user with the optimal combination of optics, detector and sample stage for their experiment with reproducible alignment every time.