Furnace E calibration

Last week I put identical ErTe3 growths in Furnace C and Furnace E, two in each furnace; both were spun at 515 C. The growths in Furnace C spun clean, whereas half of the contents of each Furnace E growth was encased in a tellurium lump.

RTe3 growers: Have you observed this tellurium lump phenomenon and have you thought about how to avoid it? My thought is that this occurs when the spin temperature is too low, and too close to the tellurium melting point.

My hypothesis is that Furnace E is calibrated so that 515 C is lower than it is in Furnace C. For this week's ErTe3 growths, I will spin Furnace E at 520 C and Furnace C at 515 C.

Any comments?