In this lecture, we're going to talk about the structure of glassy ceramics materials and how we modify the structure such that it will enable us to utilize them or work them at lower temperatures. Then we'll talk a little bit about the classes of glassy ceramics and identify some characteristic point. You just have to accept it. You will see this classification again. We talk about ceramic materials. We have our glasses, we use those for optical devices as well as containers, decoration. They're all over our lifestyle. Our clay products typically are going to be whiteware, cookware, also used for decoration of parts we use in our houses at home for decoration. Refractory bricks, these are materials that are able to withstand high temperatures. Typically, the refractory bricks are going to be loamy materials, so they are lightweight, but they can withstand a high temperature. Abrasive, we have ionic and covalent bonding in our ceramics, hence, we're going to have high bond strength, high melting points, high hardness. We can use those for cutting and polishing materials, most often diamonds, we use diamonds to polish. But also if you look at the tip of an oil drill, you will have synthetic diamonds because of their high hardness. We're familiar with cements utilizing in structural components. Then advanced ceramics. Ceramics that are used for unique applications like engine parts, sensors, and electronics. Because the oxide gate is essential component to our MOS field effect transistors. Here we have our glassy silicates, flatwear, decoration in our home. Parts used in sewage removal, water treatment, mechanical application, also containers. Ceramics used in industry, as well as our abrasives in cutting materials. We know ceramics have strong bonds, ionic and covalent bonding. Ionic directionally covalent bonds, and when we will look at this well, the direction covalent bonding for diamond and silicon carbide would also come down here as well. We have strong bond. But how can we work the material? Because if we want to work it, we want to be able to process at lower temperatures. Because of this high hardness, the melting temperature is extremely high so we have to modify the ceramic. How do we modify it? We introduce metallic ions, referred to as network modifiers. Because if I look at crystalline, let's say in this particular schematic notice I have all these covalent bonds that are attached to another covalent bond. Now I got almost all covalent bond. Now, if I introduce a network modifier, what I want to do, is break up some of these covalent bonds, lose some of the directionality of it and reduce the number of covalent bonds. By modifying this material, you can see I've opened up those covalent bonds, and also I'd lose some of the directionality of it. We said we'll do this by metallic ions. Let's look at an example. Here's a silicate glass, so the silicate is the SiO2. Now what we want to do is break up those covalent bonds. Now, you can see when I do break them up, I'm actually going to introduce more van der Waals bonding because that's going to be weak bonding. How do we do that? We're going to introduce some of these network modifiers, calcium and sodium. Doing so, we're going to often refer it to as lime soda, lime glass. I'll do it in the right sequence, soda, lime glass. What we do is we're going to break up the network. By breaking it up, it will allow us to modify the network, but also by breaking up those covalent bonds, losing some of the directionality, introducing this van der Waals bonding, I can work it at a much lower temperature as compared to just the peer quartz. By introducing this particular case, 30 percent soda lime. If not familiar with soda lime, typically a lot of the glass windows, older glass windows, the Coca-Cola bottle, for sure, those are soda-lime glass. Those you can work them, blow them typically on the order of about 600 degrees C. A relatively low temperature if you compare that to peer quartz. The network modifier, we introduce metallic ions to break up the covalent bonds, we lose a little directionality, we introduce some Van Der Waals bonding, and we're able to work at much lower temperature. In the classical case is the soda-lime glass. Even if you take some plate glass, turn it on the side, if it has a green sheen to it, I'm guaranteeing it's soda-lime glass. Let's take a moment for any inquiry. We will see this classification over and over again. We have our glasses, our clay products, our refractories, our abrasives, cement, and our advanced ceramics. Let's put out electronics here. Okay.