Breaking new ground in mica exfoliation: Harnessing biaxial straining principles through H2 and N2 intercalation for enhanced layer separation

This study introduces a novel method for mica exfoliation using biaxial straining principles through H2 and N2 intercalation. Our two-stage approach combines microwave irradiation with biaxial straining triggered by H2 and N2. Our first principles simulations showed that N2 leads to a larger drop in bulk modulus per tensile strain than H2, resulting in decreased mica strain entropy (or less disordering) and ineffective exfoliation due to the resulting positive (H2) and negative (N2) Poisson ratio. Therefore, we applied H2 and performed SEM, FT-IR, and XRD analyses. The results indicate that our pre-treatment methods did not alter the mica's crystalline structure, and our two-step treatment method increased the interlayer distances of bulk mica particles. TEM analysis revealed the presence of mica nanosheets in single layers. This study represents a significant breakthrough in 2D exfoliation research not only for mica but also for non-van der Waals bonded crystals. By utilizing innovative biaxial straining principles through H2 and N2 interclation, our approach offers a promising avenue for achieving enhanced layer separation in layered materials.