Gadolinium has a few hi-tech uses but is otherwise an obscure member of the rare earths metals group. Like the rest of the elements in this series it is an exceptionally difficult metal to isolate and doing so requires many labor-intensive steps. This difficulty in purification accounts for the high cost of the metal and is also a good reason why it is not more widely used.

A remarkable property of gadolinium is found in that when chilled this metal becomes magnetic. The Curie Point is the temperature threshold of metals exhibiting magnetism beyond which they lose this property. Where an ordinary iron magnet won’t lose that magnetism until heated past a cherry-red 770 degrees Celsius, with gadolinium this happens at 19°C, or 66F, which happens to be the temp of when you have a really good AC going during summer (or, conversely, just chilly enough in winter to get you thinking about turning on the heater). In fact, this Curie Point is so well aligned with humans’ sense of cold/warmth comfort that one could easily fashion a thermostat to get the AC (or heater!) to kick in depending on whether a gadolinium sensor within is or isn’t magnetic. Thermostat tech being already cheap and accurate it’s unlikely anyone would bother reinventing this wheel!

CAS 7440-54-2