Find the critical temperature of a bismuth based ceramic

[ronaldoshaky]

Hello to all

I recently completed an experiment trying to find the critical temperature of a bismuth based ceramic material. I cooled the sample using liquid nitrogen. I have attached my results in an excel file, where I had to plot the sample voltage (Vs) against thermocouple voltage(Vt). My question is, how do you measure the critical temperature from the graph. I was thinking it is the point where the graph gets rather steep. Any help would be appreciated.

Thanks

ps: the scale is mV

 

[pmehnati]

Hi
I think you shouid study some information about linear response theory & thermodynamics.