1. Before weighing, the crucible should be burned to a constant weight at a temperature of 900 ± 10 ℃

2. The weight of the weighed sample should be within the range of 1 ± 0.01g and the sample should be spread flat

3. High temperature furnaces should have sufficient constant temperature zones

4. The crucible must meet the requirements

During the measurement, attention should be paid to observing that the furnace temperature should recover to 900 ± 10 ℃ within 3 minutes

6. Thermocouples should be installed correctly and regularly calibrated. 7. The furnace should be sealed. 8. The crucible frame should meet the requirements.