Effect of Fe Doping on the Crystal Structure and Dielectric Properties of LiGaCr₄O₈ Breathing Pyrochlore

In this study, LiGaCr 4− x Fe x O 8 ( x = 0, 0.2, 0.4, 0.6) ceramics are synthesized using the solid‐phase reaction method. The effects of Fe doping on the lattice structure and dielectric properties are systematically examined using X‐ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and dielectric measurements. It is found from XRD analysis that the evolution of lattice constant decreases from 8.2552 Å at x = 0 to 8.2449 Å at x = 0.6, demonstrating a lattice contraction with doping. SEM shows a grain size reduction and irregular structures with higher Fe doping levels developed. The grain size decreases from 1.716 μm at x = 0 to 1.155 μm at x = 0.6. Due to Fe doping, the Raman spectroscopy obviously changes in high‐frequency phonon modes. The F 2g 1 and A 1g modes shift to higher frequencies due to the reduction in lattice constant, while the F 2g 2 , F 2g 3 , and E g modes shift to lower frequencies due to the increased ionic mass caused by the heavier Fe ions. Notably, Fe doping increases the dielectric constant and reduces the dielectric loss, especially at higher doping level. In these results, it is suggested that moderate Fe doping improves dielectric properties, offering potential applications in microwave and high‐frequency devices.