Andres Sanchez Magana - Academia.edu (original) (raw)

Papers by Andres Sanchez Magana

Research paper thumbnail of Thermal and electrical conductivity control in hybrid composites with graphene and boron nitride fillers

Materials Research Express, 2019

We report on the thermal and electrical properties of hybrid epoxy composites with graphene and b... more We report on the thermal and electrical properties of hybrid epoxy composites with graphene and boron nitride fillers. The thicknesses, lateral dimensions, and aspect ratios of each filler material were intentionally selected for geometric similarity to one another, in contrast to prior studies that utilized dissimilar filler geometries to achieve a "synergistic" effect. We demonstrate that the electrically-conductive graphene and electrically-insulating boron nitride fillers allow one to effectively engineer the thermal and electrical conductivities of their resulting composites. By varying the constituent fraction of boron nitride to graphene in a composite with ~44% total filler loading, one can tune the thermal conductivity enhancement from a factor of ×15 to ×35 and increase the electrical conductivity by many orders of magnitude. The obtained results are important for the development of next-generation thermal interface materials with controllable electrical properties necessary for applications requiring either electrical grounding or insulation.

Research paper thumbnail of Dual‐Functional Graphene Composites for Electromagnetic Shielding and Thermal Management

Advanced Electronic Materials, 2018

We report on the synthesis and characterization of the epoxy-based composites with the few-layer ... more We report on the synthesis and characterization of the epoxy-based composites with the few-layer graphene fillers, which are capable of the duel functional applications. It was found that composites with the certain types of few-layer graphene fillers reveal an efficient total electromagnetic interference shielding, ~45 dB, in the important X-band frequency range, = 8.2 GHz − 12.4 GHz, while simultaneously providing the high thermal conductivity, ≈ 8 Wm −1 K −1 , which is a factor of ×35 larger than that of the base matrix material. The efficiency of the dual functional application depends on the filler characteristics: thickness, lateral dimensions, aspect ratio and concentration. Graphene loading fractions above the percolation threshold allow for strong enhancement of both the electromagnetic interference shielding and heat conduction properties. Interestingly, graphene composites can block the electromagnetic energy even below the percolation threshold, remaining electrically insulating, which is an important feature for some types of thermal interface materials. The dual functionality of the graphene composites can substantially improve the electromagnetic shielding and thermal management of the airborne systems while simultaneously reducing their weight and cost.

Research paper thumbnail of Phonon and Thermal Properties of Quasi-Two-Dimensional FePS3 and MnPS3 Antiferromagnetic Semiconductors

ACS Nano, 2020

We report results of investigation of the phonon and thermal properties of the exfoliated films o... more We report results of investigation of the phonon and thermal properties of the exfoliated films of layered single crystals of antiferromagnetic FePS3 and MnPS3 semiconductors. The Raman spectroscopy was conducted using three different excitation lasers with the wavelengths of 325 nm (UV), 488 nm (blue), and 633 nm (red). The resonant UV-Raman spectroscopy reveals new spectral features, which are not detectable via visible Raman light scattering. The thermal conductivity of FePS3 and MnPS3 thin films was measured by two different techniques: the steadystate Raman optothermal and transient time-resolved magneto-optical Kerr effect. The Raman optothermal measurements provided the orientation-average thermal conductivity of FePS3 to be 1.35 ± 0.32 Wm −1 K −1 at room temperature. The transient measurements revealed that the through-plane and in-plane thermal conductivity of FePS3 is 0.85 ± 0.15 Wm −1 K −1 and 2.7 ± 0.3 Wm −1 K −1 , respectively. The films of MnPS3 have higher thermal conductivity of 1.1 ± 0.2 Wm −1 K −1 through-plane and 6.3 ± 1.7 Wm −1 K −1 in-plane. The data obtained by both techniques reveal strong thermal anisotropy of the films and the dominant contribution of phonons to heat conduction. Our results are important for the proposed applications of the antiferromagnetic semiconductor thin films in spintronic devices.

Research paper thumbnail of Thermal and electrical conductivity control in hybrid composites with graphene and boron nitride fillers

Materials Research Express, 2019

We report on the thermal and electrical properties of hybrid epoxy composites with graphene and b... more We report on the thermal and electrical properties of hybrid epoxy composites with graphene and boron nitride fillers. The thicknesses, lateral dimensions, and aspect ratios of each filler material were intentionally selected for geometric similarity to one another, in contrast to prior studies that utilized dissimilar filler geometries to achieve a "synergistic" effect. We demonstrate that the electrically-conductive graphene and electrically-insulating boron nitride fillers allow one to effectively engineer the thermal and electrical conductivities of their resulting composites. By varying the constituent fraction of boron nitride to graphene in a composite with ~44% total filler loading, one can tune the thermal conductivity enhancement from a factor of ×15 to ×35 and increase the electrical conductivity by many orders of magnitude. The obtained results are important for the development of next-generation thermal interface materials with controllable electrical properties necessary for applications requiring either electrical grounding or insulation.

Research paper thumbnail of Dual‐Functional Graphene Composites for Electromagnetic Shielding and Thermal Management

Advanced Electronic Materials, 2018

We report on the synthesis and characterization of the epoxy-based composites with the few-layer ... more We report on the synthesis and characterization of the epoxy-based composites with the few-layer graphene fillers, which are capable of the duel functional applications. It was found that composites with the certain types of few-layer graphene fillers reveal an efficient total electromagnetic interference shielding, ~45 dB, in the important X-band frequency range, = 8.2 GHz − 12.4 GHz, while simultaneously providing the high thermal conductivity, ≈ 8 Wm −1 K −1 , which is a factor of ×35 larger than that of the base matrix material. The efficiency of the dual functional application depends on the filler characteristics: thickness, lateral dimensions, aspect ratio and concentration. Graphene loading fractions above the percolation threshold allow for strong enhancement of both the electromagnetic interference shielding and heat conduction properties. Interestingly, graphene composites can block the electromagnetic energy even below the percolation threshold, remaining electrically insulating, which is an important feature for some types of thermal interface materials. The dual functionality of the graphene composites can substantially improve the electromagnetic shielding and thermal management of the airborne systems while simultaneously reducing their weight and cost.

Research paper thumbnail of Phonon and Thermal Properties of Quasi-Two-Dimensional FePS3 and MnPS3 Antiferromagnetic Semiconductors

ACS Nano, 2020

We report results of investigation of the phonon and thermal properties of the exfoliated films o... more We report results of investigation of the phonon and thermal properties of the exfoliated films of layered single crystals of antiferromagnetic FePS3 and MnPS3 semiconductors. The Raman spectroscopy was conducted using three different excitation lasers with the wavelengths of 325 nm (UV), 488 nm (blue), and 633 nm (red). The resonant UV-Raman spectroscopy reveals new spectral features, which are not detectable via visible Raman light scattering. The thermal conductivity of FePS3 and MnPS3 thin films was measured by two different techniques: the steadystate Raman optothermal and transient time-resolved magneto-optical Kerr effect. The Raman optothermal measurements provided the orientation-average thermal conductivity of FePS3 to be 1.35 ± 0.32 Wm −1 K −1 at room temperature. The transient measurements revealed that the through-plane and in-plane thermal conductivity of FePS3 is 0.85 ± 0.15 Wm −1 K −1 and 2.7 ± 0.3 Wm −1 K −1 , respectively. The films of MnPS3 have higher thermal conductivity of 1.1 ± 0.2 Wm −1 K −1 through-plane and 6.3 ± 1.7 Wm −1 K −1 in-plane. The data obtained by both techniques reveal strong thermal anisotropy of the films and the dominant contribution of phonons to heat conduction. Our results are important for the proposed applications of the antiferromagnetic semiconductor thin films in spintronic devices.