This family of cylindrical crucibles are available in SPI-Glas™ 22 and can therefore be used to 3000 °C, which is the evaporation temperature of all carbon products generally. In vacuum some evaporation can start occurring above 2000 °C.
Always remember that SPI-Glas™ 22 Glassy Carbon Crucibles are a far lower cost alternative to the use of platinum, and one does not generally have to worry about "mysterious disappearances" of their valuable crucibles either. For many procedures, glassy carbon is better than platinum because of its much higher corrosion resistance (against sodium peroxide, Fe, Cr, Ni, and other elements that quickly allow with platinum). And of course the glassy carbon crucibles, in vacuum, have far higher temperature resistance than platinum since they can be taken to 3000 °C.