Ultrahigh thermal conductivity in isotope-enriched cubic boron nitride

Abstract

Materials with high thermal conductivity (κ) are of technological importance and fundamental interest. We grew cubic boron nitride (cBN) crystals with controlled abundance of boron isotopes and measured κ greater than 1600 watts per meter-kelvin at room temperature in samples with enriched 10B or 11B. In comparison, we found that the isotope enhancement of κ is considerably lower for boron phosphide and boron arsenide as the identical isotopic mass disorder becomes increasingly invisible to phonons. The ultrahigh κ in conjunction with its wide bandgap (6.2 electron volts) makes cBN a promising material for microelectronics thermal management, high-power electronics, and optoelectronics applications.

Shear wave generation by mode conversion in picosecond ultrasonics: Impact of grain orientation and material properties

“…Several representative metals suitable for transducer applications and commonly available using conventional film deposition techniques are considered and listed in Table 1. Ceria (CeO 2 ), thoria (ThO 2 ), strontium titanate (SrTiO 3 ), yttria‐stabilized zirconia, H 2 S pressured at 6 GPa, and cubic boron nitride (cBN) are chosen as substrate materials of interest for a range of applications due to their attractive physical properties 13,41‐43 . Their elastic properties are summarized in Table 1 and capture a broad range of values for elastic constant and density.…”

The Properties and Preparation Methods of Different Boron Nitride Nanostructures and Applications of Related Nanocomposites

“…[82,83] In an inert atmosphere such as nitrogen or argon, its resistance to heat decomposition can be up to 2000°C, especially for c-BN up to 3000°C. [36,84] It can withstand 2950°C in an active atmosphere of ammonia. According to the calculation formula of thermal conductivity k = � • C p • ρ (where k is thermal conductivity, � is thermal diffusivity, C p is the specific heat at constant pressure and ρ is density), the out-plane thermal conductivity of BN is about 33 W/m • K and in-plane thermal conductivity is as high as 125 W/m • K, which make it outstanding among the thermally conductive materials.…”

“…Boron nitride has high thermal stabilities and it can't be oxidized within 850 °C in air atmosphere [82,83] . In an inert atmosphere such as nitrogen or argon, its resistance to heat decomposition can be up to 2000 °C, especially for c‐BN up to 3000 °C [36,84] . It can withstand 2950 °C in an active atmosphere of ammonia.…”

Phonons of hexagonal BN under pressure: Effects of isotopic composition

“…Another route to increase thermal conductivity is isotope engineering, which allows the reduction of phonon scattering by isotopic disorder to be achieved in isotopically purified crystals [7,8]. Very recently, an ∼90% enhancement of the room-temperature thermal conductivity to ultrahigh values over 1600 W m −1 K −1 was reported in isotopically enriched c- 10 BN [9]. In-plane thermal conductivity as high as 585 W m −1 K −1 was measured at room temperature in monoisotopic 10 BN [10].…”