I am using a tube furnace to anneal the sample in presence of Argon. Can I do sudden cooling after the heat treatment over at such high temperature? Will it be any problem to the furnace?
If the tube in your furnace is Al2O3 ceramic then no, but if tube is stainless steel or fused silica then yes.
Yes you can do by a simple trick, I hope your tube furnace is open at either end, and probably at present it is horizontal.
Make it vertical.
Take a quartz ampule with a small hook, you glass blower cant do it easily working with quartz, fill you powder into it, and get it vacuum sealed first.
Suspend your ampule with a suitable wire to withstand the furnace temperature (sometime you may need a Pt wire). introduce the ampule into the central zone of the furnace, where your temperature is maximum and you have the flat zone.
Now underneath the furnace you keep a a long vertical double flask /thermocole container filled with liquid nitrogen. Sone after the prescribed time, your material melts in the ampoule (Temp. and time to be decided by you), cut the wire of the ampoule at the top end from where you have suspended, the ampoule will fal into the LN2 continer, and you can quench. This is how I used to make my glasses in a simple way, and is a standard technique.
Sorry for the spelling mistake in my previous reply. You glass blower can make such an ampule having a small hole, or a hook at one of the ends to tie the Pt wire (or high temperature withstanding wire).