How to Use a Thermogravimetric Analyzer to Measure Loss on Mass in Alumina

Thermogravimetric analysis (TGA) is a vital technique for analyzing the thermal stability and composition of materials by measuring the mass change as a function of temperature. In the context of alumina (Al₂O₃), TGA helps identify thermal events such as dehydration, dehydroxylation, and decomposition of impurities. This article provides a detailed procedure for using a thermogravimetric analyzer to measure the loss on mass in alumina, incorporating specific considerations for accurate and reliable results.

Materials and Equipment

• Thermogravimetric Analyzer (TGA)
• Alumina Sample
• Crucible (typically made of platinum or alumina)
• Balance for initial weighing
• Protective Equipment (gloves and goggles)

Procedure

Sample Preparation

• Weigh the Sample

Accurately weigh a small amount of the alumina sample using a high-precision balance. Recording the initial mass is crucial for accurate data analysis later. Ensure the sample is representative of the bulk material, minimizing changes during preparation and avoiding contamination.

• Place in Crucible

Transfer the weighed sample into a clean crucible suitable for TGA analysis. Alumina or platinum crucibles are preferred because of their high-temperature stability and chemical inertness. The porosity of the crucible should be considered. Open porosity crucibles allow better gas exchange. This is beneficial for experiments requiring gas flow. However closed porosity crucibles are suitable for reactive or volatile samples.

Setting Up The Thermogravimetric Analyzer

• Calibrate the Thermogravimetric Analyzer

Follow the manufacturer’s instructions to calibrate the thermogravimetric analyzer. Calibration ensures the accuracy and reliability of the thermogravimetric analyzer’s measurements, which may involve running a calibration standard or verifying the baseline.

• Load the Sample into the Thermogravimetric Analyzer

Place the crucible containing the alumina sample into the thermogravimetric analyzer’s sample holder. Ensure proper placement to avoid errors during the analysis.

Running the Analysis

• Set Temperature Program

Program the thermogravimetric analyzer to heat the sample at a controlled rate, typically 10°C per minute. Set the final temperature high enough to ensure complete decomposition or reaction of the sample, usually up to 1000°C or higher for alumina. 

• Select Atmosphere

Choose the appropriate atmosphere for the analysis. An inert gas like nitrogen or argon is often used to prevent oxidation. However, if oxidation is part of the study, air can be used as the atmosphere.

• Start the Analysis

Begin the TGA run. The thermogravimetric analyzer will continuously record the mass of the sample as the temperature increases.

Data Collection and Analysis

• Monitor the Run

Observe the TGA curve in real-time if possible. The curve will show the mass loss as the temperature increases, indicating different thermal events.

• End the Run

Once the temperature program is complete, allow the sample to cool before handling. That way safety can be ensured and thermal burns can be avoided.

• Analyze the Data

Identify the points of mass loss on the TGA curve. These points correspond to the temperatures at which different components of the sample decompose or react. For alumina samples, look for mass loss events indicating loss of adsorbed moisture, dehydroxylation of aluminum hydroxides, or decomposition of impurities.

Calculating Loss on Mass

• Determine Mass Loss

Calculate the total mass loss by comparing the initial mass of the sample to the final mass after the TGA run. This data is crucial for understanding the composition and thermal stability of the alumina sample.

• Interpret Results

The mass loss can be attributed to the decomposition of specific components within the alumina sample, such as:

• The loss of adsorbed water
• Decomposition of impurities
• Phase changes in the alumina.

Additionally, the shape and particle size of the alumina sample can affect gas diffusion during analysis. Larger solid pieces typically exhibit higher decomposition temperatures compared to granular or fine-grained samples.

Reporting Results

• Document Findings

Record the initial and final masses, the temperature program, and the atmosphere used. Include the TGA curve in your report for a comprehensive analysis.

• Discuss Implications

Explain the significance of the mass loss in the context of your specific application or research. This could include the purity of the alumina, the presence of contaminants, or the thermal stability of the material.

Utilize our Thermogravimetric Analyzers and Insights on Thermogravimetric Analysis to Fuel Your Knowledge

By meticulously following these steps and considerations, you can effectively use a thermogravimetric analyzer to measure the loss on mass in alumina. The process behind a thermogravimetric analyzer provides valuable information about the material’s thermal stability and composition.

For a more comprehensive understanding of thermogravimetric analysis, we invite you to read our Beginner’s Guide to Thermogravimetric Analysis. It offers in-depth explanations and additional tips to help you master a thermogravimetric analyzer and achieve precise, reliable results. Alongside our articles, we also supply thermogravimetric analyzers, such as our xrTGA 1100. This type of thermogravimetric analyzer can be utilized for loss on mass in alumina, offering an extremely high throughput, thanks to its carousel with 30 spaces for samples, an interface that is simple to use, and speed in relation to its cooling and heating cycles. Apply our thermogravimetric analyzers and see the difference they can make to your work.