Method of Rapid (100,000 K/s) Controlled Cooling and Heating of Thin Samples

摘要

A method of rapid controlled cooling and heating of thin samples is developed. The apparatus comprises of a membrane with a thin-film resistor and a sample, a narrow gap between the membrane and a heat sink, and a control circuit. The resistor acts both as a heater and as a temperature sensor to reduce time constant of the control circuit. The gap between the membrane and the heat sink is filled with gas (e.g., N_2 or He) acting as cooling medium with low thermal inertia. The control circuit applies given rate of temperature changes and measures the power, released on the heater, to determine sample thermal properties such as heat capacity, exothermal/endothermal heat flow, thermal conductivity, etc. The method allows realizing fast (10~5 K/s) controlled (e.g., linear) cooling and heating rates regardless of thermal events in a sample, and fast (～10 microseconds) switching between ramps and isotherms. Beside calorimetry, the method can be used in a variety of applications, requiring rapid controlled temperature changes of a sample, and in studying of fast thermal processes.