Editing Differential scanning calorimetry (section)

==Experimental considerations==
There are various experimental and environmental parameters to consider during DSC measurements. Exemplary potential issues are briefly discussed in the following sections. All statements in these paragraphs are based on the books of Gabbott <ref>{{cite book |last1=Gabbott |first1=Paul |title=Principles and applications of thermal analysis |date=2008 |publisher=Blackwell Pub |location=Oxford |isbn=978-14-051-3171-1}}</ref> and Brown.<ref>{{cite book |last1=Brown |first1=Michael E. |title=Handbook of Thermal Analysis and Calorimetry, Volume 1 - 1st Edition |date=1998 |publisher=Elsevier Science |isbn=978-00-805-3959-1}}</ref>

===Crucibles===
DSC measurements without crucibles promote the thermal transfer towards the sample and are possible if the DSC is designed for this purpose. Measurements without crucible should only be conducted with chemically stable materials at low temperatures, as otherwise there may be contamination or damage of the calorimeter. The safer way is to use a crucible, which is specified for the desired temperatures and does not react with the sample material (e.g. alumina, gold or platinum crucibles). If the sample is likely to evolve volatiles or is in the liquid state, the crucible should be sealed to prevent contamination. However, if the crucible is sealed, increasing pressure and possible measurement artefacts due to deformation of the crucible must be considered. In this case, crucibles with very small holes (∅~50&nbsp;μm) or crucibles that can withstand very high pressures should be used.

===Sample condition===
The sample should be in good contact with the crucible surface. Therefore, the contact surface of a solid bulk sample should be plane parallel. For DSC measurements with powders, stronger signal might be observed for finer powders due to the enlarged contact surface. The minimum sample mass depends on the transformation to be analyzed. A small sample mass (~10&nbsp;mg) is sufficient if the released or consumed heat during the transformation is high enough. Heavier samples could be used to obtain transformation associated with low heat release or consumption, as larger samples also enlarge the obtained peaks. However, the increasing sample size might worsen the resolution due to thermal gradients which may evolve during heating.

===Temperature and scan rates===
If the peaks are very small, it is possible to enlarge them by increasing the scan rate. Due to the faster scan rate, more energy is released or consumed in a shorter time which leads to higher and therefore more distinct peaks. However, faster scan rates lead to poor temperature resolution because of thermal lag. Due to this thermal lag, two phase transformations (or chemical reactions) occurring in a narrow temperature range might overlap. Generally, heating or cooling rates are too high to detect equilibrium transitions, so there is always a shift to higher or lower temperatures compared to phase diagrams representing equilibrium conditions.

===Purge gas===
Purge gas is used to control the sample environment, in order to reduce signal noise and to prevent contamination. Mostly nitrogen is used and for temperatures above 600&nbsp;°C, argon can be utilized to minimize heat loss due to the low thermal conductivity of argon. Air or pure oxygen can be used for oxidative tests like oxidative induction time and He is used for very low temperatures due to the low boiling temperature (~4.2K at 101.325 kPa <ref>{{cite book |last1=Mortimer |first1=Charles E. |last2=Müller |first2=Ulrich |last3=Beck |first3=Johannes |title=Chemie: das Basiswissen der Chemie: 410 Abbildungen, 545 Formelbilder |date=2015 |publisher=Georg Thieme Verlag |location=Stuttgart New York |isbn=978-31-348-4312-5 |edition=12., korrigierte und aktualisierte Auflage}}</ref>).