Hello. I'm an undergraduate researcher at a new lab.

I'm having trouble controlling the oxygen atmosphere in a three-zone tube furnace that we received from a retired professor's lab. I don't have anyone to ask for guidance, and my professor is unfamiliar with three-zone furnaces.

I need to achieve consistent results for three samples at the same temperature and time settings, but some are working well while others aren't. The sealing seems fine, and I've ensured that there's no external air entering (I've maintained internal pressure and sealed the inlet and outlet).

Could you please advise on what flow rate of oxygen gas is typically used for experiments like this? Also, given the tube's dimensions (approximately 8 cm in diameter and 120 cm in length) and the sample placement at 41 cm, 55 cm, and 69 cm from the inlet, how should I set the heating zones for optimal results? The alumina boat holding the samples is 1 cm high and 10 cm long. I've attached an oil line to the outlet to prevent backflow of external air, so the internal pressure is maintained only to the height of the oil line. Should I be adjusting the internal pressure further?

Regarding the masks, the outlet has a hose in the center, and I recently switched the inlet to a mask with oxygen coming in from the side. Could you advise on which type of mask is better to use?

I've tried various flow rates, ranging from 300 cc/min to 1500 cc/min, but I'm still having trouble maintaining the oxygen atmosphere. Please help.

For your information, I'm using LiOH and Ni(OH)2 as precursors, and the product is LiNiO2 (a transition metal oxide).

I apologize for my writing and lack of structure. Being in a new lab with limited resources and guidance from anyone other than my professor, I've been struggling for months. I'm at a loss on how to proceed, so I'm reaching out here for help. Please, any assistance would be greatly appreciated!