Thought Leaders

Using X-Ray Diffraction to Study the Crystal Growth of New Materials

An interview with Professor Hans-Conrad zur Loye, conducted by Alina Shrourou BSc.

Please explain the types of materials that you are interested in for your research.

We use crystal growth to synthesize a variety of new materials for different purposes. We prepare oxides, fluorides and chalcogenides with desired structures and specific magnetic and optical properties.

How are those materials used?

We investigate the crystal growth of new materials, including new scintillating and luminescing oxides and fluorides, and new uranium and thorium containing structures. In the case of the latter, we synthesize new hierarchical wasteform materials for the effective immobilization of nuclear waste in persistent architectures.

How do you use XRD to better understand those materials?

To evaluate the success of a crystal growth experiment, we perform powder X-ray diffraction experiments to obtain information about known phases that are present. Additionally, and perhaps more importantly to us, to also infer the presence of new phases.

Using phase matching, we can identify known materials - if we cannot match the pattern, then we suspect that we have a new material. We then use single crystal X-ray diffraction using our D8 QUEST instrument. This is performed initially to test crystal quality, and then to collect full data sets on high quality crystals. We also perform EDS on all crystals to confirm the elemental composition.

Please give an overview of your recent work developing new complex oxides in novel structure types.

For our research in new wasteform materials, we are exploring new salt inclusion phases. These are porous silicates, germanates, phosphates and mixed alumino-phosphates. The framework can contain radionuclides, such as uranium, plutonium and ideally technetium, while the salt inclusion can be ion exchanged and a non-radioactive version replaced with troublesome radioactive isotopes, such as iodine, cesium and strontium.

In the area of scintillation materials, we are focusing on compositions that would make for good neutron scintillators. These materials can be used for the detection of fissile materials and also in new detector systems in neutron diffraction systems. In addition, we are pursuing oxide fluorides, such as Cs3TbSi4O10F2, which exhibits intense X-ray scintillation.

We are preparing other porous structures including zeolitic materials that exhibit high temperature magnetic order and new iron frameworks.

Single Crystals of Cs3F(UO2)(Si4O10) © Hans-Conrad zur Loye

What role does XRD play in your research into these complex oxides?

We rely on powder X-ray diffraction for routine phases analysis and sample purity determinations. This is typically done on benchtop D2 PHASER instruments. They are simple to use and very fast with a silicon strip detector, making them perfect for our research applications and it’s an extra bonus that they don’t take up much space.

Single crystal diffraction is also essential for our work as it lets us determine the atomic structures and in the case of ion exchange reactions, allow us to follow structural changes by single crystal to single crystal transformations.

How has your relationship with Bruker allowed you to develop your research?

We have a good relationship with Bruker which has been maintained even after buying the instrument, and this is not something that you often see.

We purchased our first single crystal instrument in 2001 and have worked with Bruker ever since on single crystal X-ray diffraction. Their customer service is very important to us and the fact that they are responsive, helps us diagnose problems remotely and allows us to perform repairs.  If they are beyond our skill, they come and fix it without hesitation. With our new instrument we used that to solve a software question, but otherwise had no need to call on them.

In addition to research materials, the other thrust for academia is to enable researchers of tomorrow. Do your students perform the XRD measurements?

All my students, including the undergraduates, run powder X-ray diffraction. The D2 PHASER is easy and safe to use, so I don’t need to worry about my undergraduates or graduate students using them after they complete their radiation safety training. All my graduate students collect their own single crystal data and mostly solve their own structures, comfortably doing so with the D2 PHASER. We also have a phenomenal departmental crystallographer with his own D8 QUEST, who provides us with his insights when we are stuck.

How has it been made easy for them to perform XRD measurements?

The software integration of the D8 QUEST makes data collection and crystal quality determination easy.  We train all new students and once they solve their first structure, they are hooked.

About Professor Hans-Conrad zur Loye

Dr. zur Loye is the David W. Robinson Palmetto Professor in the Department of Chemistry and Biochemistry and the Associate Dean for Research and Graduate Education in the College of Arts and Sciences at the University of South Carolina. He received his Bachelor of Science Degree at Brown University in 1983 and his Ph.D. in Chemistry from the University of California, Berkeley in 1988.

His research group explores the crystal growth of new materials, including new scintillating and luminescing oxides and fluorides, and new uranium and thorium containing structures.  In the latter case, he targets new hierarchical wasteform materials for the effective immobilization of nuclear waste in persistent architectures.

He has published over 400 papers and reviews. He is an internationally recognized leader in his research field and, as a result, has received numerous awards, including the Exxon Award in Solid State Chemistry, the University of South Carolina Educational Foundation Award for Research in Science, Mathematics and Engineering, and the IPMI Henry J. Albert Award in 2009.

Additionally, Dr. zur Loye is an associate editor for the Journal of Solid State Chemistry and a past editor for the Journal of Alloys and Compound. 

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