Zevalkink Lab

This project will involve studying the thermal properties of new semiconducting materials with potential applications as thermoelectrics. Thermoelectric devices are fully solid-state systems (no moving parts) that convert heat into electrical energy or vice versa via the Seebeck or Peltier effects.  Such devices are currently used by NASA as the primary power source for missions throughout the solar system. The thermal conductivity of the semiconductors in these devices is crucial because low thermal conductivity helps maintain a large temperature gradient, which is necessary for efficient conversion of heat to electrical energy. In our lab, we measure the thermal conductivity of new materials using a method called “light flash diffusivity” as a function of temperature.  We also measure speed of sound as a function of temperature using “resonant ultrasound spectroscopy”, which measures the resonant frequencies of a sample.  During the 10 week program, the student, together with a graduate student mentor, will conduct these measurements on a series of samples, analyze the data and compare the results with prior work, and present the results both to our group and at the MSU-wide undergraduate research conference.

Scientific goals:   

• Combining these thermal conductivity with speed of sound measurements allows us to interpret trends in thermal conductivity as a function of  composition, crystal structure, and temperature.
• Our ultimate goal is to understand how the crystal structure (atomic arrangement) in semiconductors controls their ability to conduct heat, especially at high temperatures.

Student learning goals: 

• Operating principles and applications of thermoelectric devices
• Basic material design principles for efficient thermoelectric materials
• Relationship between ability of a semiconductor to conduct heat and its compositions and other physical properties

Left:  Crystal structure of a thermoelectric material next to the measurement setup for resonant ultrasound spectroscopy, which measures the speed of sound in a material.  Right: Prof Zevalkink (2^nd from the right) and three of her Ph.D. students at an annual department event at the Spartan Stadium.