Structural and electromagnetic shielding of ZnO ceramics in X-band

In recent years, there has been an increase in interest in advancing the development of high-performance microwave shielding materials against electromagnetic interference. In this study, the electromagnetic shielding properties of ZnO ceramic based on conventional technique and high-energy planetary ball milling technique (HEPBM) have been analyzed in the frequency range of 8–12 GHz (X-band). The EMI shielding characteristics and all S parameters (S₁₁ & S₁₂) of both ball-milled and conventional ZnO ceramic pellets were measured in the frequency range of X-band using a Vector Network Analyzer (VNA). The results showed that the average crystallite size of ball-milled and conventional ZnO ceramic pellets was obtained to be 16.75 nm and 21.93 nm, respectively. The absorption (SE_A) improves from 4 to 26 dB in the HEPBM approach, resulting in an absorption-dominated EMI shielding effect, and the highest total shielding effectiveness (SE_T) is 26.30 dB with a thickness of 1.83 mm. The real part of permittivity (ε′) value was found to be 15 for ball-milled ZnO and 3 for conventional ZnO, respectively. The real part of complex permeability (μ′) value was found to be 4 for ball-milled ZnO and 1 for conventional ZnO in the frequency range of 8–9 GHz. These results indicate that milled ZnO is a promising EMI shielding material as compared to conventional ZnO and can be used as a potential microwave absorber in the X-band frequency.