In this work, we synthesized mixed-phase hexagonal-boron nitride (h-BN)/cubic-BN (c-BN) composites with varying ratios and investigated their frequency and temperature-dependent dielectric properties. As the ratio of c-BN increased, we observed a corresponding increase in the dielectric constant of the composites. Furthermore, we used spark-plasma sintering (SPS) to treat the mixed-phase composite, which resulted in a phase transformation from mixed phase to pure h-BN phase. Remarkably, the composite exhibited an increase in dielectric constant after the SPS process, which can be attributed to the densification of the composite and the enhancement in grain size. Our approach presents a promising strategy for effectively modulating the dielectric properties of BN, which is crucial for advanced electronics.

M. Xu, Z. He, A. Biswas, S. Luo, T. Li, C. Chang, C. Li, B. Gao, R. Vajtai, P. Dai, P. M. Ajayan, and Y. Zhao, “Modulation of dielectric properties of hexagonal/cubic boron nitride composites“, Appl. Phys. Lett., vol. 124, 192903 (2024).