It is no secret that materials science encompasses a wide range of techniques, all with the aim of analyzing different types of materials that may later serve as candidates for numerous technological applications.
Since I started writing on the STEEM platform I have dedicated myself to sharing different publications related to semiconductors, starting from theory, growth techniques and characterization through different methods. Likewise, these techniques are not only used to study semiconductor compounds, but also materials of organic and inorganic nature, substances, gases, among others.
A clear example of this is my spectroscopy series, where it includes different analysis techniques that play a fundamental role in different areas of science, their simple utility, characterize materials that are later applied in their related area.
Next in this publication I am going to show you a small introduction on another type of techniques of characterization of materials such as those of thermal analysis, which include a set of methods that are in charge of studying the physical and chemical properties of different materials depending on their temperature. These techniques have a wide application with regard to minerals, metals, alloys, plastics, semiconductors, substances, medicines. All this serves as a quality control of all products derived from those already mentioned.
Heat can cause different changes in the physical properties of a material, which is why different techniques were created to help interpret this behavior. One of those changes that materials can suffer is for example in its crystalline structure, the atoms inside its network can move due to the change of temperature that they can suffer, in the same way its chemical composition can present some changes as, for example: to pass from a solid state to a liquid state, to this it is called fusion, or it can also suffer a change of supplication that translates in being in liquid state and then to pass to a gaseous state. The materials can also solidify or crystallize, alter, oxidize or perhaps decompose which are some of the reactions that can occur due to temperature changes. There have been cases where they can also change their size either smaller or larger, but one of the most important as I just mentioned is to move from one structure to another to this is called transition.
All these changes we can interpret always varying the temperature and thus measuring in each scale we can observe in detail interesting changes in their properties, all this always as a function of temperature.
So, if a company wants to manufacture any kind of material in the first place it must go through a very thorough quality control, all this in order to be able to manufacture a perfect material. For example if we buy a reclining or swivel chair and this in a few days breaks for no reason, or at the time we want to turn its bearings are broken and detached, this means that the material with which this product was manufactured is of poor quality or simply not performed a proper quality control.
The quality of a product for any consumer is vital to take a challenge. Errors such as the above example are costly and harm both the consumer and the manufacturer.
But what is the real reason why the product failed?
Design errors, poor quality, inadequate materials or poor processing of these materials. That is why it is very important to determine if a material presents the correct properties for its use. Here is the importance of selecting the right materials and thus optimize the production processes necessary for their manufacture.
Some examples of application are the identification of polymers by their transition temperature, melting and crystallization temperatures, chemical composition analysis and decomposition behavior as shown in a later post when talking about the thermogravimetric method .
Other processes in the determination of mechanical parameters such as the coefficient of thermal expansion or its module.
It is here the importance of knowing these methods of thermal analysis and next I will show you only some of the most known, to later enter fully to explain each of these methods in different publications.
Some of the techniques to study these temperature changes in materials are:
Thermogravimetry, when we want to measure its mass this is the appropriate technique, as it is based specifically on measuring the variation in weight that a material can present when subjected to "X" temperature. If we want to observe volume changes this is ideal. These changes in mass can be losses or gains, depending on the type of material we are analyzing. The programs that use thermogravimetric methods are very sophisticated, they do not provide information through the recording of measurements if the analyzed material decomposes or reacts to various temperature factors.
One of the most important advantages of thermogravimetry is that it can be coupled with other techniques such as differential thermal analysis or differential scanning calorimetry, these help to complement the study and give effective results regarding the changes occurred in their properties.
It is also important to note that this method of thermal analysis can be coupled with other methods such as: thermal difference, quarterly scanning, mass spectroscopy, FTIR spectroscopy and more.
Another well-known method is Differential Thermal Analysis, which is the appropriate technique for measuring the changes in energy that a material can present when subjected to a certain temperature. In the first place we must have a reference material to be able to carry out the measurement, this material must remain inert, then when submitting them to a variation of temperature, the team of analysis is in charge of collecting the data that measures the difference of temperature between the sample that we want to analyze and the reference material, all this always in function of a constant temperature or the maximum reached at that moment.
The DTA measures the difference in temperature vs. temperature or time. All measurements can be made in an environment totally controlled by us or also in normal temperature conditions, depending on what we want to measure or obtain. If we calibrate the equipment in a perfect way we can obtain different results, for example, we know that this type of techniques is of qualitative analysis because exothermic or endothermic processes are involved in the material to be analyzed, however it can be transformed into a semi-quantitative techniques that allows us to obtain precise information about the amount of heat involved in the process of measuring the sample.
In particular, the study of semiconductor compounds is ideal to obtain a phase diagram, which allows us to see the melting point of each element. As well as to observe if a phase transition occurs.
Differential scanning calorimetry is another of the most widely used techniques, it studies the changes that occur in the heat flow as a function of temperature or time. Some of the processes that occur in this analytical method is the determination of boiling points, crystallization, solidification and specific heat of the materials to be analyzed, ie all possible enthalpy variables.
The main objective of differential calorimetry is to be able to obtain all the necessary information on the changes that occur in the different enthalpy variables. In this case, it is also necessary to have an inert reference material in order to carry out a comparative study.
Some techniques of thermal analysis
Cover image source:
