Extremely large range regulation of thermal conductivity of penta-BCN by tensile strain

Abstract

Two-dimensional pentagonal materials have emerged as a promising research frontier since the discovery of penta-graphene, owing to their distinctive structural configurations and tunable physical properties. In this work, we systematically investigate the strain-dependent thermal transport characteristics of penta-BCN monolayers through first-principles calculations combined with the Boltzmann transport equation. Remarkably, the thermal conductivity undergoes a dramatic three-order-of-magnitude reduction under 16 % uniaxial strain, decreasing from 166.5 W/mK (pristine) to 0.5 W/mK (x direction). In-depth analysis reveals that strain-induced bond elongation in B-C and N-C linkages significantly disrupts electron cloud symmetry, thereby enhancing structural anharmonicity. This amplified anharmonicity triggers a corresponding three-order-of-magnitude augmentation in phonon scattering rates and a comparable reduction in phonon relaxation time. The synergetic effects of these factors ultimately account for the observed exceptional suppression of thermal conductivity. These findings reveal the phonon-strain coupling mechanisms in pentagonal materials and provide critical insights for designing strain-tunable thermal devices.