Fig. 3

a Calibration curve for low-temperature measurements (20–100 °C); black, red and purple lines correspond to 18.4, 34.0 and 83.6 °C temperature curves, respectively. b Calibration curve for high-temperature measurements (100–300 °C); black, red, purple, brown and yellow lines correspond to 83.7, 133.4, 183.4, 233.1 and 282.9 °C temperature curves, respectively. This is used to determine thermal conductivity based on the relationship between thermal resistance and the temperature difference of the sample and reference calorimeter