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.
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.
The thermal analysis laboratory at Keyworth plays a key role in projects that span the BGS science programme, for example:
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.
Please contact Simon Kemp for further information