Thermal and thermoelectric transport measurements of an individual boron arsenide microstructure

Abstract

Recent first principles calculations have predicted that boron arsenide (BAs) can possess an unexpectedly high thermal conductivity that depends sensitively on the crystal size and defect concentration. However, few experimental results have been obtained to verify these predictions. In the present work, we report four-probe thermal and thermoelectric transport measurements of an individual BAs microstructure that was synthesized via a vapor transport method. The measured thermal conductivity was found to decrease slightly with temperature in the range between 250 K and 350 K. The temperature dependence suggests that the extrinsic phonon scattering processes play an important role in addition to intrinsic phonon-phonon scattering. The room temperature value of (186 ± 46) W m−1 K−1 is higher than that of bulk silicon but still a factor of four lower than the calculated result for a defect-free, non-degenerate BAs rod with a similar diameter of 1.15 μm. The measured p-type Seebeck coefficient and thermoelectric power factor are comparable to those of bismuth telluride, which is a commonly used thermoelectric material. The foregoing results also suggest that it is necessary to not only reduce defect and boundary scatterings but also to better understand and control the electron scattering of phonons in order to achieve the predicted ultrahigh intrinsic lattice thermal conductivity of BAs.

First-principles prediction of stabilities and instabilities of compounds and alloys in the ternary B-As-P system

“…The experimental values of κ of BAs are, however, approximately 10 times smaller than the theoretical value (∼200 W m −1 K −1 ) [10,11]. Such a reduction in κ of BAs has been suggested to be originating from the presence of As vacancies, since the as-synthesized BAs samples were arsenic-deficient [10][11][12]. At T ∼ 1190 K, BAs irreversibly decomposes into boron subarsenide (B 12 As 2 ) due to the evaporation of As from BAs [13][14][15].…”

“…This is in line with our prediction that BP is the stable compound in the B-P system. On the other hand, only tiny millimeter-sized crystalline samples of BAs have so far been achieved in the experiments [5,10,11]. This is probably limited by the thermal decomposition of BAs into B 12 As 2 due to the evaporation of As from BAs at elevated temperature [13][14][15], where the atomic diffusion is usually playing a role.…”

“…BAs has recently received special attention, as it has been predicted from the first-principles approach to have a remarkably high value of thermal conductivity (κ) at room temperature (2240 W m −1 K −1 ), comparable to that of diamond [9]. The experimental values of κ of BAs are, however, approximately 10 times smaller than the theoretical value (∼200 W m −1 K −1 ) [10,11]. Such a reduction in κ of BAs has been suggested to be originating from the presence of As vacancies, since the as-synthesized BAs samples were arsenic-deficient [10][11][12].…”

Disordered Icosahedral Boron-Rich Solids: A Theoretical Study of Thermodynamic Stability and Properties

“…) [103,104]. Such a reduction in κ of BAs has been suggested to be originating from the presence of As vacancies, since the assynthesized BAs samples were As-deficient [103][104][105].…”

“…Such a reduction in κ of BAs has been suggested to be originating from the presence of As vacancies, since the assynthesized BAs samples were As-deficient [103][104][105]. Consequently, synthesizing idealized stoichiometric BAs with high crystalline quality is still a practical challenge, which is questionable whether BAs is a stable compound in the binary B-As 1.6 Boron subnitride 9 system.…”