Specifically when produced with "exceptional purity"...
Wikipedia [0] lists room temperature thermal conductivity at 1300 W/(m·K) and says "Chemical synthesis of cubic BAs is very challenging and its single crystal forms usually have defects." I guess it remains to be seen how cheaply and easily this "exceptional purity" can be achieved.
Boron Arsenide has been found to have thermal conductivity at room temperature of 2100 W/m, greater than that of diamond.
Specifically when produced with "exceptional purity"...
Wikipedia [0] lists room temperature thermal conductivity at 1300 W/(m·K) and says "Chemical synthesis of cubic BAs is very challenging and its single crystal forms usually have defects." I guess it remains to be seen how cheaply and easily this "exceptional purity" can be achieved.
[0] https://en.wikipedia.org/wiki/Boron_arsenide