I need to control a certain process depending upon the temperature readings from a sensor.

The temperature sensor has to be perfectly isolated from a container, because the container reaches very high temperatures that could damage the thermistor used to capture its(the container's) temperature. So I'm looking for a material that could transfer a range of temperature that is suitable for the sensor, calibration will then be carried out to control the process.
Container temperature level:
0 - 300 degrees Celsius ...
temperature sensor's limits:
0 - 150 degrees Celsius ...