High Thermal Conductivity in Isotopically Enriched Cubic Boron Phosphide

Abstract

Zinc blende boron arsenide (BAs), boron phosphide (BP), and boron nitride (BN) have attracted significant interest in recent years due to their high thermal conductivity (Λ) predicted by first-principles calculations. This research reports the study of the temperature dependence of Λ (120 K < T < 600 K) for natural isotope-abundance BP and isotopically enriched 11 BP crystals grown from modified flux reactions. Time-domain thermoreflectance is used to measure Λ of sub-millimeter-sized crystals. At room temperature, Λ for BP and 11 BP is 490 and 540 W m −1 K −1 , respectively, surpassing the values of conventional high Λ materials such as Ag, Cu, BeO, and SiC. The Λ of BP is smaller than only cubic BN, diamond, graphite, and BAs among single-phase materials. The measured Λ for BP and 11 BP is in good agreement with the first-principles calculations above 250 K. The quality of the crystals is verified by Raman spectroscopy, X-ray diffraction, and scanning transmission electron microscopy. By combining the first-principles calculations and Raman measurements, a previously misinterpreted Raman mode is reassigned. Thus, BP is a promising material not only for heat spreader applications in high-power microelectronic devices but also as an electronic material for use in harsh environments.

Thermoelectric transports in pristine and functionalized boron phosphide monolayers

“…At 300 K, the calculated k la of BP monolayer is 205.3 W/mK. Unlike the common trend where two-dimensional materials possess higher k la than their bulk compounds 21 , the k la of BP monolayer is lower than the measured result for BP crystal (460–490 W/mK) 39 , 40 , which may due to the different atomic arrangements in monolayer BP and bulk BP. Similar to graphene, the ZA phonons dominate the thermal transport among all the phonons in BP.…”

Ultrahigh thermal conductivity in isotope-enriched cubic boron nitride

“…3C and fig. S28), especially for c 10 BN and c 11 BN where long-MFP phonons have larger relative contribution to κ and therefore experience a stronger size effect.…”

Advanced Materials for High‐Temperature Thermal Transport

“…Kang et al obtained room temperature κ of 460 W m −1 K −1 . Zheng et al measured κ of natural and isotope‐free BP crystals and compared with first‐principles calculation. The measured κ at room temperature is 490 and 540 W m −1 K −1 for natural and isotopically pure BP.…”