Inorganic engineering is the study of the properties of inorganic materials that do not contain carbon, mainly metal oxides, which are used as advanced materials such as catalysts, superconductors, and memristors.
A few years ago, I came across an article on an internet site by a student who wanted to go into inorganic engineering. I was excited to see that he was talking about inorganic materials engineering, but I remember being a little disappointed to see that he was talking about missiles and bombs. I’m sure there are many of you who thought of ‘weapons’ when you first heard the name ‘Department of Inorganic Materials Engineering’, or at least many of you who wondered, “What is inorganic materials engineering?” So I would like to take this opportunity to introduce inorganic materials engineering in general.
Inorganic is in contrast to organic, which you may be familiar with. Organic matter is the stuff that makes up life, or is made by life, and it all contains carbon. Inorganic matter is the opposite of organic matter, meaning it doesn’t contain carbon. For example, the proteins and fats that make up our bodies are organic, whereas metals like iron and aluminum and substances like water, salt, and iodine are inorganic. Soil, especially silica, is a typical inorganic material, and the term inorganic engineering used to be used instead of ceramics, which refers to the firing of clay to make pottery. Today, inorganic engineering is sometimes referred to as ceramics, which is also derived from ceramics.
However, mineral engineering doesn’t cover all inorganic materials – there’s no point in studying ceramics or salt nowadays, and there are so many different types of metals that there’s a separate field of study called metallurgy. So, what exactly does mineral engineering study? To find out, we need to take a quick look at the types of elements that exist on Earth.
There are 118 elements that have been discovered so far, but only 92 exist stably in their natural state, excluding those that have been synthesized artificially. These elements are divided into metallic and non-metallic elements, with metallic elements far outnumbering non-metallic elements by 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 atoms of different elements combine to form different substances. For example, lead atoms come together to form lead ingots, and carbon atoms, a non-metal, come together to form diamonds. Salt is formed when sodium atoms, which are metals, combine with chlorine atoms, which are nonmetals. Just by looking at lead, diamonds, and salt, we can see that different atoms combine to create very different properties.
Going back to inorganic engineering, the objects of study in inorganic engineering are typically materials formed by the combination of metal and non-metal atoms. The salt mentioned above is an example of this. In particular, inorganic materials are materials that combine metal atoms with oxygen atoms, which are a major subject of research due to their large number and excellent properties. They are called “metal oxides” because they are formed through an oxidation process in which metals combine with oxygen. Let’s take a look at the importance of metal oxides in current and future industries.
The primary current use of metal oxides is as catalysts. A catalyst is a substance that increases the rate of a chemical reaction, making it easier for the reactants to react. In industry, catalysts play a very important role, first by speeding up reaction times so that more product can be made in the same amount of time, and second by enabling reactions to take place at relatively low temperatures and air pressures, reducing production costs. Catalysts first came to prominence in the 1830s and have remained essential to all industries ever since.
So how do metal oxides catalyze chemical reactions? For example, let’s say a substance reacts with oxygen. In the absence of metal oxides, the reactant would react with oxygen from the air, but the oxygen in the air is in a stable molecular state and doesn’t readily participate in the reaction. If you add metal oxides as a catalyst, however, the metal oxides provide oxygen atoms, allowing the reaction to occur quickly. Compared to oxygen in the air, the oxygen atoms provided by the metal oxide are very unstable and will try to combine quickly with the reactants, thus speeding up the reaction.
The above explanation is just a simple example to help you understand, and the actual principles of how metal oxide catalysts work are much more complex and varied, which is why they are still being actively researched.
Metal oxides are also a promising new material for the future. For example, copper oxide mixed with calcium and barium forms superconductors. Superconductors are materials that lose their resistance below a certain temperature and have potential applications in energy storage and maglev trains. However, most superconductors are difficult to apply in real life because they only show superconductivity below minus 200℃, but copper oxide superconductors show superconductivity even at minus 120℃~150℃, so their use is limited. If research continues, it is expected that superconductors that work at room temperature will be discovered or synthesized.
In recent years, researchers have also been working to develop new memory devices using certain metal oxides, such as titanium oxide. In metal oxides, oxygen atoms have a negative charge, and when a positive voltage is applied, the oxygen atoms move toward the electrode. When the voltage is removed, the oxygen atoms stay where they are, causing the metal oxide to “remember” the time the voltage was applied. This is what led to the development of a device called a memristor. Memristors are expected to enable computers that don’t need to boot up, and even computers with artificial intelligence.
Metal oxides are also used as piezoelectric materials for exploration and communication equipment because they change shape when electricity flows through them and generate electricity when they change shape, and as heat-resistant materials for furnaces because of their ability to withstand high temperatures.
This is a brief introduction to the Department of Materials Science and Engineering. To summarize, inorganic engineering focuses on the study of materials composed of metallic and non-metallic elements, especially metal oxides composed of metal and oxygen. Currently, metal oxides are widely used as industrial materials such as catalysts, and are gaining attention as high-tech materials such as superconductors and memristor devices. Of course, this is by no means an exhaustive list of the department’s research interests, as a wide variety of inorganic materials play important roles in a wide range of fields. For the sake of space, I’ve focused on metal oxides, but I’d like to emphasize that there are many other inorganic materials being studied, including nitrides, sulfides, and silicides.
You may have been a little disappointed that it wasn’t the “inorganic engineering” that you had imagined, but I hope that you came away with a better understanding of what inorganic engineering is all about, and that you left thinking, “This inorganic engineering is interesting.” Thank you.
