Engineering Ceramics with Desired Microstructures

Scientists from the Materials Science and Engineering Department at Lehigh University have developed a novel approach that could revolutionize ceramic fabrication. This advancement has the potential to enable improved technologies, including more efficient electronics, enhanced sensors, and possibly new types of energy devices.

Creating ceramics with customized geometries has always been difficult. Achieving this level of customization would allow for the development of materials with unique structures that enhance properties like strength, heat resistance, or electrical conductivity.

The National Science Foundation funded the study.

This is a new type of ceramic material that has not been studied much. Typically, when you have a reaction, a certain type of microstructure develops. The systems we are studying give us the potential for predetermining the microstructure, almost like templating.

Helen M. Chan, Professor, Lehigh University

The objective is to create a useful material with a specific geometry, or microstructure, for various applications. The team has employed a technique called solid-state synthesis, where a chemical reaction between two different phases forms a new third phase with a controlled, predetermined shape.

In this case, the desired product is an entropy-stabilized ceramic, which remains thermodynamically stable at high temperatures. This method allows for the precise creation of materials with new features that were previously unattainable.

Chan likened the process to laying two different types of patio pavers in a garden.

Grass grows at the interface between the different stones, and it is the grass phase that we are interested in. By putting the stones in a certain arrangement, we are controlling where and how much grass there is. We want to control that third phase, the grass, if you will, in the reaction.

Helen M. Chan, Professor, Lehigh University

During the research, the team made an unexpected discovery about the third phase.

Chan said, “That third phase was a single crystal, and it is usually very difficult to get single-crystal growth that you can template. The combination of the single-crystal interface with those other two phases could, in fact, contribute to the functional properties of the system.”

This ability to create single-crystal phases with specific microstructures could lead to technological advancements in electronics, energy conversion, and other fields. For example, the materials might be used in thermoelectric devices that generate power from waste heat.

These thermoelectrics are highly desirable because they can convert heat energy into a voltage, which is a more useful form of electrical energy.

Jeffrey M. Rickman, Professor, Lehigh University 

In addition to practical applications, the research aims to explore fundamental questions about the mechanisms driving solid-state synthesis by combining advanced modeling with experimental work.

Rickman said, “We want to understand the physics behind the reaction, and the modeling aspect will allow us to model the formation of this new useful phase. How do the atoms come together? How does the material deform during a reaction? How does this long-range transport of the atoms at the interface occur? It is an interesting project in that we are both producing new and useful products, but we are also contributing to the fundamental science driving these reactions.”