Differential scanning calorimetry is a classic method for determining the specific heat of materials at constant pressure, but its accuracy is affected by multiple factors. To achieve high-precision measurement, it is necessary to optimize the system from various aspects such as instruments, samples, operations, and data processing.

Firstly, strict instrument calibration and baseline stability are the foundation. High purity standard substances (such as sapphire) must be used for specific heat capacity calibration to eliminate systematic errors caused by instrument constants. At the same time, it is necessary to ensure the cleanliness of the instrument furnace body and obtain a smooth and highly repeatable baseline through multiple empty crucible scans, which is the key to accurately deducting background heat flux.

Secondly, precise sample preparation and control of experimental parameters are crucial. The sample should be of moderate quality (usually 5-15mg) and ensure close contact with the bottom of the crucible to reduce thermal resistance and ensure good thermal conductivity. The sample form is preferably a flat sheet or powder evenly spread. During the experiment, a sufficiently slow heating rate (such as 2-5K/min) must be selected. Excessive heating rate can introduce dynamic hysteresis error due to the temperature gradient inside the sample, seriously affecting the accuracy of measurement results.

Furthermore, adopting the three line measurement mode is the core optimization strategy. Perform three scans of blank baseline, standard sample (sapphire), and test sample in sequence under the same conditions. This method can ensure the consistency of experimental conditions to a certain extent, and accurately calculate the specific heat capacity by calculating the ratio of (test sample signal baseline) to (standard sample signal baseline), effectively offsetting systematic errors.

Finally, standardized data processing. Before calculation, it is necessary to carefully check and ensure that the baselines of the three heat flow curves coincide, and correct any minor drift. Select the heat flux data of samples and standards in a stable state (non reaction zone) for calculation, avoiding interference areas such as phase transitions and reactions.

In summary, through a series of interrelated strategies such as precise instrument calibration, optimized sample preparation, slow heating rate, standard three line measurement, and rigorous data processing, the accuracy and reliability of DSC in determining specific heat at constant pressure can be systematically improved, providing accurate data support for material thermal properties research.