My research interests lie in the synthesis and characterization of new, improved materials for both clean energy applications and for electronic materials such as piezoelectrics and multiferroics, with a focus on using environmentally benign materials with low toxicity. The development of new advanced functional materials with both high performance and a low energy impact is one of the most important challenges in the scientific community today as the current energy economy, based on fossil fuels is at serious risk. These goals will be achieved through studying the structure-property relationships of advanced materials. By taking materials and definitively characterizing their complex structural features it is possible to gain insight into what drives its behavior. The key aspect of the relationship between the structure of a material and its properties is often overlooked, but through a complete understanding of the structure-property relationships of known structures, it will be possible to rationally design and tune new materials with the desired properties.
Some of our projects include:
Structure-Property Relationships of Piezoelectric Materials
The piezoelectric effect occurs when an electrical charge is generated through an external strain and the opposite can also occur where an applied charge will cause the material to deform. We synthesize piezoelectric bulk and thin film materials to address a need for new materials to replace Pb(Zr,Ti)O3 (PZT), which is toxic to the environment and also to address a need for materials with a higher piezoelectric response at elevated temerpatures. Despite the tremendous effort made by scientists to make lead-free piezoelectrics, little progress has been made and only small incremental improvements have occured. Our group focuses on the structure-property relationships of piezoelectric materials to help lead us to a rational design of new materials. We use X-ray and neutron diffraction to determine the crystal structure, then we use Pair Distribution Function analysis to look at any variations between the local and average structures. By understanding how the structure drives the behavior of these materials, we will be able to understand what is necessary to increase the piezoelectric response to equal or surpass the performance of PZT.
Materials Design of Novel Multiferroics
Multiferroic materials exhibit more than one of the following properties: ferromagnetism, ferroelectricity, and ferroelasticity. The two main challenges in the quest for new multiferroic materials are 1) the tendency for magnetic ordering to occur only at very low temperatures and 2) the difficulty in finding a material where the magnetic and electronic properties are strongly coupled. Our group is working to synthesize and characterize novel multiferroic materials that possess a layered perovskite structure. Our goal is to understand the structure-property relationships that encourage strong coupling and use that as a basis for rational design of new and improved multiferroic materials.
Pair Distribution Function Studies of Amorphous and Nanocrystalline Materials
We collaborate with the Wager, Keszler, and Cheong group here at Oregon State to understand the structure-property relationship in amorphous metal films and amorphous oxide semiconductors. Our group performs total scattering experiments to determine and model the pair distribution function of our materials. This problem is incredibly challenging as the materials we look at do not have any long range ordering and are thus difficult to model accurately. We use the information obtained from the PDF along with data from other complementary techniques to understand the structure of these amorphous materials. The structure provides the key link between the properties measurements performed by the Wager and Keszler group and the computations of the Cheong Group.
As part of our work with the Center for Sustainable Materials Chemistry (CSMC), we are collaborating with the Nyman Group to understand how polyoxometallate precursors transform into metal oxide thin films using the CSMC's aqueous solution deposition method. We have performed variable temperature total scattering experiments to observe and ultimately understand the structural transformation from amorphous cluster to crystalline oxide.
The Dolgos group is open to collaboration. We enjoy designing and synthesizing new materials and can provide expertise in structural characterization. Please email us if you would like to work together!
Some of our research is funded by the Center for Sustainable Materials Chemistry, a Phase II NSF-funded center.