What is Inorganic Engineering? Exploring the world of inorganics and metal oxides!

This article provides a general introduction to inorganic engineering. The word “inorganic” in inorganic engineering refers to inorganic materials, not weapons, and the field primarily studies metal oxides, which are composed of metallic and non-metallic elements. Metal oxides are used in a variety of advanced materials such as catalysts, superconductors, and memristor devices, and are expected to play an important role in future industries. In this article, we’ll talk about what inorganic engineering studies and the applications of metal oxides.

 

A few years ago, I came across an article on an internet site where a student wrote that he hoped to enter the Department of Inorganic Engineering. I was excited to see that it was about inorganic materials engineering, but instead, it was all about missiles and bombs, and I remember being a little disappointed. I’m sure many of you, not just this student, but many of you, when you first heard the name ‘Department of Weapons and Materials Engineering’, you thought of the word ‘weapons’, or at least you didn’t think of it that way, but I’m sure there are many of you who are wondering, “What does weapons engineering study?” So I would like to take this opportunity to give you a general understanding of weapons engineering.
The opposite of “inorganic” in inorganic engineering is “organic,” which I’m sure you’re familiar with. Organic matter is the material that makes up life or is made by life, and all of these materials are composed of carbon. Therefore, the opposite of organic matter, inorganic matter, is material that does not contain carbon. For example, the proteins and fats that make up our bodies are organic substances that contain carbon, while metals such as iron and aluminum, and substances such as water, iodine, and salt are inorganic. Soil, which is made up of silicon, is a typical inorganic substance, and in the past, the term inorganic engineering was used in place of ceramic engineering, which refers to the firing of clay to make pottery. Nowadays, mineralogy is often referred to as ceramics, which also comes from the word ceramics.
However, inorganic engineering does not cover all inorganic substances. The study of ceramics or salt has become irrelevant in the modern era, and metals are so numerous and wide-ranging that there is a separate field of study called metallurgical engineering. So what exactly does inorganic engineering study? To better understand this, it is necessary to briefly review the types of elements that exist on Earth.
There are 118 elements that have been discovered so far, but if we consider only those that can exist stably in their natural state, excluding those that have been synthesized artificially, there are 92. These elements can be divided into metallic and non-metallic elements, with metallic elements being much more numerous than non-metallic elements, with about 70. Typical metallic elements include iron, copper, gold, silver, and aluminum, while nonmetallic elements include carbon, oxygen, sulfur, and hydrogen. Each element exists as tiny particles called atoms, and when atoms of different elements come together, they form different substances. For example, when lead atoms clump together, they literally form a lump of lead, and when carbon atoms, a non-metal, clump together, they form a diamond. Salt is made of sodium atoms, which are metals, and chlorine atoms, which are non-metals. Just by looking at lead, diamonds, and salt, we can see that different types of atoms can have completely different properties depending on how they come together.
Now, let’s get back to inorganic engineering, where the materials we study are usually made up of a combination of metallic and non-metallic atoms. The salt mentioned above is an example of this, but the most studied materials are those that are composed of metal atoms and oxygen atoms, probably because they are the most numerous and have the best properties. These materials are called metal oxides because they are formed through an oxidation process in which pure metal atoms come into contact with oxygen atoms and combine. Let’s take a look at each of these metal oxides and their importance in current and future industries.
One of the most common applications of metal oxides today is catalysis. In simple terms, a catalyst is a substance that increases the rate of a chemical reaction. More specifically, they are substances that help reactants react faster by making it easier for them to react. The role of catalysts in industry is crucial because, first, they reduce reaction times, which means that more product can be produced in the same amount of time, and second, they allow reactions to take place at relatively low temperatures and pressures, which reduces production costs. As a result, catalysts have been indispensable in all industries since they were first discovered in the 1830s.
But how exactly do metal oxides catalyze chemical reactions? To understand this, imagine a substance reacting with oxygen. In the absence of metal oxides, this reactant would react with oxygen in the air, but the oxygen in the air exists as a molecule, which is relatively stable and therefore unlikely to react well with the reactant. On the other hand, if you add a specific type of metal oxide as a catalyst, the metal oxide will provide an oxygen atom. These oxygen atoms are very unstable compared to the oxygen molecules in the air, so they want to combine quickly with the reactants, resulting in a faster reaction rate.
However, this is just a simple example to help you understand how metal oxide catalysts work, and the principles are much more complex and there are many different ways in which they work, which is why many people are still actively researching them.
Metal oxides are also a promising new material for the future. For example, copper oxide mixed with calcium and barium forms superconductors, which you may have heard of. A superconductor is a material that has the property that resistance disappears below a certain temperature, and it is expected to be used in energy storage and maglev trains in the future. There are many materials that exhibit superconductivity, but most of them are below minus 200℃, so it is almost impossible to use them in real life. On the other hand, superconductors made of copper oxide show superconductivity even at minus 120℃~150℃, so they are currently used to a limited extent. If research continues in this direction, we may one day be able to discover or synthesize superconductors that work at room temperature.
In addition, there is a growing expectation that new memory devices can be created by utilizing the voltage-dependent migration of oxygen atoms in certain metal oxides such as titanium oxide. Specifically, oxygen atoms in metal oxides have a negative charge. Positive and negative charges attract each other, so if you apply a positive voltage to one side of the metal oxide, the oxygen atoms will migrate to that side. If you remove the voltage, the oxygen atoms will stay where they are because there is no longer a force that attracts them. The position of the oxygen atoms depends on the length of time the voltage was applied, so the metal oxide can be said to remember the time the voltage was applied. This ability to remember is the basis of a device called a memristor, which is a very interesting device because it could be used to create computers that don’t need to boot up, and ultimately computers with artificial intelligence.
In addition, piezoelectric materials that can be used in various exploration equipment and communication equipment because they have the property of changing shape when electricity is applied and generating electricity when the shape changes, and heat-resistant materials that can withstand high temperatures and are used in furnaces are also based on metal oxides.
So far, I have given you a general introduction to the Department of Inorganic Engineering. To summarize briefly, the Department of Inorganic Engineering studies materials composed of metallic and non-metallic elements, especially metal oxides composed of metallic and oxygen elements. I mentioned that metal oxides are currently used as catalysts and are attracting great attention as advanced materials such as superconductors and memristor devices. Of course, this is by no means the entirety of the Department of Inorganic Engineering. Metal oxides play an important role in a very wide range of fields, and there are many topics to be studied in the future. Furthermore, while I have focused on metal oxides for the sake of space, I would like to emphasize that many other inorganic materials such as nitrides, sulfides, silicides, etc. are studied and utilized.
Perhaps you may have been disappointed that this is not the “inorganic engineering” you thought it would be, but I hope that you can get a general idea of what inorganic engineering is all about, and that you can go away with the feeling that “this inorganic engineering is also interesting.” Thank you.