Introduction to Differential Scanning Calorimetry Practical Course (English version, Sept. 2002) Contact : Dr. R. Nicula Physics Dept., Rostock University e-mail :
[email protected] Thermoanalytical Methods 1. Overview 2. Differential Thermal Analysis (DTA) 2.1. Introduction. 2.2. DTA Instrument. 2.3. Experimental details : potential sources of error. 2.4. Data analysis. 3. Differential Scanning Calorimetry (DSC) 3.1. Introduction 3.2. Heat-flux DSC Systems 3.2.1. Basic Components. 3.2.2. Analysis of Heat-Flow in a Heat-Flux DSC. 3.2.3. Temperature Calibration. 3.2.4. Enthalpy Calibration. 3.2.5. Baseline substraction. Transformation Curves. 3.3. Applications of Differential Scanning Calorimetry 3.3.1. Continuous Heating/Cooling Experiments. 3.3.2. Isothermal Experiments : Kinetics of Phase Transitions. 3.4. The NETZSCH 404C Pegasus DSC/DTA/Cp Instrument 3.4.1. Basic components, technical features & specimen environment. 3.4.2. Operation Manual. 3.4.3. Data Analysis Procedures. Introduction to the Proteus software. 3.5. Experimental Module Implementation (in preparation) Other Thermoanalytical Methods (optional) 4. Thermal-modulated DSC (TMDSC) 5. Thermogravimetric Analysis (TGA) 6. Dilatometry (DIL) 7. Related Experiments : Temperature-resolved X-ray Diffraction List of Symbols and Abbreviations Further Reading Useful Links 1. Overview Thermal analysis comprises a group of techniques in which a physical sample property is measured as a function of temperature, while the sample is subjected to a predefined heating or cooling programme. In differential thermal analysis (DTA), the temperature difference between a sample and an inert reference material is measured, when both are subjected to identical heat treatments. The related technique of differential scanning calorimetry (DSC) relies on differences in energy required to maintain the sample and reference at an identical temperature. Both thermogravimetry (TGA) and evolved gas analysis (EGA) are techniques which rely on samples which decompose at elevated temperatures. The former monitors changes in the mass of the specimen on heating, whereas the latter is based on the gases evolved on heating the sample. Electrical conductivity measurements can be related to changes in the defect density of materials or to study phase transitions. Length or volume changes that occur on subjecting materials to heat treatment are detected in dilatometry (DIL). X-ray or neutron diffraction can also be used to measure dimensional changes. 2. Differential Thermal Analysis (DTA) 2.1 Introduction The principle of the DTA technique resumes to heating (or cooling) a test sample (S) and an inert reference (R) under identical conditions while measuring the temperature difference ∆T between S and R. The differential temperature ∆T is then plotted against time or against temperature. Chemical, hysical, structural and microstructural changes in the sample S lead to the absorption (endothermal event) or evolution of heat (exothermal event) relative to R. If the response of two inert samples submitted to an applied heat-treatment programme is not identical, differential temperatures ∆T arise as well. Therefore, DTA can also be used to study thermal properties and phase changes which do not necessar