Magnetic structure and colossal dielectric properties in Ga3+ substituted Zn2Y hexaferrites by chemical co-precipitation method

Y-type Ba_0.5Sr_1.5Zn₂Fe_12-xGa_xO₂₂ (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) hexaferrites are prepared through modified chemical co-precipitation method. X-ray diffraction (XRD) results reveal that these samples are single-phase and the space group is $R\bar{3}m$. The field-emission scanning electronic microscope (FE-SEM) measurements indicate that the grains are hexagonal-plate with a diameter of 2–5 μm. In the M-T diagrams, various magnetic structures are modulated, including proper-screw, longitudinal conical (LC), mixed conical (MC), and collinear ferrimagnetic (collinear FIM). In this series of samples, the values of dielectric constant (${\epsilon }^{\prime }$) achieve an order increase from 10² to 10⁴. For the best x = 0.8 sample, the ${\epsilon }^{\prime }$ is as high as 1804.76 at 1 MHz and 300 K. In conclusion, Ba_0.5Sr_1.5Zn₂Fe_12-xGa_xO₂₂ with controllable magnetic structures and colossal dielectric constant are potential materials for miniaturization of modern electronic devices.