Kieran Brooks Master’s Thesis Defense, Thursday, April 30, 2026 @ 12:00 pm Central Time

COMMITTEE CHAIR: Dr. Harshica Fernando

COMMITTEE CO-CHAIR: Dr. Kevin Storr

TITLE: IONIZATION EFFECTS ON FERRITES FOR SPACE APPLICATIONS: A RAMAN SPECTROSCOPY STUDY

ABSTRACT: To explore space safely, multifunctional materials are needed. They need to be readily accessible, as rare earth metals are difficult to source. Rare-earth-free magnetic materials continue to attract attention in energy, electronics, electromagnetic, and space applications, especially where material cost, sustainability, and structural performance are important. Among these materials, Minnealloy has emerged as a promising future soft magnetic system because of its high saturation magnetization and critical-material-free design. To study Minnealloys, a set of precursor Ferrite spinels was used for their chemical stability, soft magnetic behavior, and suitability for high- frequency applications in space. In this work, the structural and vibrational behavior of three ferrite samples, pure NiFe2O4, pure ZnFe2O4, and a combination of both Zn and Ni as Ni0.5Zn0.5Fe2O4, were irradiated and investigated before and after radiation using Raman spectroscopy. Raman measurements were performed at room temperature using 785 & 455 nm laser excitation. To assess the stability of ferrites in space, radiation studies were conducted. The ferrite samples were exposed to 0.1, 0.5, and 1.0 Mrad at a dose rate of 54 krad/min, followed by Raman analysis. Key observations of radiation-exposed samples showed that the main shifts in Raman peaks are due to oxygen stretching in the crystalline lattice. The work suggests a local increase in density with increasing radiation dose.

Keywords: Minnealloy, Ferrite Spinels, Raman Spectroscopy, NiFe2O4, ZnFe2O4, Ni0.5Zn0.5Fe2O4, Soft Magnetic Materials, X-ray Irradiation

Room Location: EE O’Banion Science Building (New Science Building), RM 203.