Abstract:The widespread use of thermal analysis (TA) by scientists as a laboratory technique carries with it a working vocabulary. This document is intended to provide those working in the field with a consistent set of definitions to permit clear and precise communication as well as understanding. Included in the document are the definitions of 13 techniques, 54 terms within the glossary, as well as symbols and units.

A new, high-resolution system for analyzing and characterizing materials is described. Based on evolved gas analysis (EGA), it can perform both controlled transformation rate thermal analysis and stepwise isothermal analysis as well as conventional (linear temperature program) EGA. Features include a fastresponse furnace, direct temperature measurement, sensitive specific detector, and sophisticated temperature control. The system permits, for the first time, a comparison of the three modes of operation under an identical sample environment. The advantages and limitations of each are illustrated using a sample chosen to model a type of reaction often found in the preparation of catalysts by calcination, the thermal decomposition of hydroxides. It is shown that these methods used with our system have potential advantages in analysis and in the study of complex thermal decomposition processes, by increasing the resolution of consecutive events and providing a more closely controlled sample environment.In conventional thermal analysis the sample is made to follow a predetermined, usually linear, temperature program while one or more of its properties, e.g., mass loss, energy change, or gas evolution, is measured. To improve resolution and provide better conditions for kinetic studies, a number of workers have developed techniques in which variable heating rates are used.1-1 1 2 These differ from normal thermoanalytical procedures in that the heating rate is not predefined but is altered as a consequence of some change in a monitored parameter of the sample, e.g., in TG it would be the reaction rate as determined from the rate of change of sample mass.

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