I'm trying to source an alternate thermistor for one that became unavailable, and the old part lists on its datasheet "RT curve Y". I know that the RT curves of thermistors differ based on the material and doping concentrations etc, but I can't seem to find any reference material about these different curve types. On a datasheet for another brand of thermistor, there's a specification called "Material System" which I think might be related, listing options F, Y, H, G, etc. Can anyone point me to some free literature online about this? I can't find much useful information from Google or Wikipedia. Thanks much.