Thermal analysis

Thermal analysis is a term for a group of methods that involve measuring and interpreting a range of properties that occur when a sample is subjected to a controlled heating programme, typically from ambient to 1 000°C.

Thermal analysis techniques are employed to study both inorganic and organic reactions and by comparison with reaction stoichiometry can be used to identify, characterise and quantify the nature of geological and soil materials. For earth science applications, thermal analyses are particularly useful in studying carbonate-, clay- and hydrated mineral-bearing samples.

Thermal analyses are often most usefully performed in tandem with X-ray diffraction analyses.


Mettler-Toledo SDTA 851e, sample robot
Mettler-Toledo TGA/SDTA 851e with linked Pfeiffer Vacuum ThermoStar mass spectrometer system

Techniques

Thermogravimetric analysis (TGA) involves measuring the mass change of a substance as a function of temperature through a controlled heating programme. Results are presented as a plot of mass against temperature or time and any mass loss or gain is therefore presented as a step in the generated profile. Derivative (DTG) curves may also be presented to indicate the rate of mass loss/gain and facilitate the identification of overlapping reactions.

Allied techniques such as differential thermal analysis (DTA) detect thermal changes (exothermic or endothermic) in a sample in response to heating or cooling by reference to an inert reference. Typically, a DTA curve will be presented alongside a TG/DTG curves to aid interpretation.

Evolved gas analysis (EGA), using a linked mass spectrometer, measures and investigates the amount of volatile products released by a sample during a controlled heating programme. By calculating the masses of gas evolved, the presence and concentration of very low levels of mineral/organic species can be determined.

Equipment

  • state-of-the-art Mettler-Toledo SDTA/TGA 851e simultaneous thermal analysis system, 34-position sample changer, high temperature furnace (1 500°C) for either routine or research analyses
  • Linked Pfeiffer Vacuum ThermoStar mass spectrometer system to detect and quantify evolved gas species, 0 – 200 amu

Applications

The thermal analysis laboratory at Keyworth plays a key role in projects that span the BGS science programme, for example:

  • detection and quantification of low levels of carbonate species for radioactive waste disposal and carbon dioxide capture/storage
  • speciation and quantification of soil organic matter, particularly with regard to black carbon and assessing soil carbon stocks
  • quantification of kaolinite in beneficiation trials leading to the development of industrial mineral deposits
  • characterisation of carbonate mineralogy as part of limestone assessment surveys
  • determining the contribution of carbonate minerals to the engineering behaviour of rocks and soils

Staff and facilities are also in constant demand for direct consultancy analysis and interpretation by external clients including: oil, mineral and mining companies; engineering and utility companies; consultancies; university departments and local authorities.

Contact

Please contact Simon Kemp for further information