Temperature and Frequency Effects on the Dielectric Properties of the Nematic Liquid Crystal 8CB By Dr. Chandra Prayaga Ross Dickenson Josh Barbee

Overview Liquid crystals defined Applications of liquid crystals UWF Department of Physics research in liquid crystals Results

Liquid Crystals Materials that have intermediate states between the solid and the liquid phases

Applications Display Technology –Laptop Computers –Digital Watches Aquarium Thermometers Waveguide Optical Switch

UWF Physics LC Research Optical Properties Thin Films Microscopy Electrical: changes in dielectric properties with frequency and temperature

RC - Circuit

Capacitor Construction

Temperature Control

Experimental Apparatus

Data Collection Cycle Φ = F (freq, Temp) Set Temperature Increase Temperature and Repeat Record Phase Angle from Lock-In Amplifier Select Frequencies

Graph of Data

Our Findings Combinations of Temperature and Frequency Contribute to Phase Angle Increasing Temperature at any frequency results in a lower phase angle At low frequency, room temperature, 8CB behaves like a normal dielectric 8CB’s behavior charges dramatically at transition temperature and medium frequencies

Future Efforts Refine temperature control Gather more low frequency data in the region of 26deg Apply a magnetic field and determine upper and lower bounds on the dielectric constant due to alignment of molecules