[MUSIC] Hello everyone, in this lecture we are talk about the classification of ceramics. So now you know that the ceramics are nonmetallic, inorganic materials, and they include the oxide, nitride, carbide, boride, silicide, sulfide, and glass. So most of the common form of ceramics are oxide and they can be classified according to their functions. Based on the electrical properties of ceramics, as shown here, you can find a lot of functions of ceramics. The barium titanate, strontium titanate with perovskite structure and tantalum oxide are ferroelectric ceramics. These materials are widely used for ceramic capacitor. The PZT, the titanium doped lead zirconate oxide with perovskite structure is an important piezoelectric materials, to which it can be used to pull the power generation by the mechanical energy and an actuator. The PLZT, lanthanum titatium doped lead zirconate oxide is an electro-optical ceramics. Due to their high stability, even at higher temperatures, and good the optical transmittance, this material is used for window material in the high temperature processes. The barium magnesium tantalum oxide barium zinc titanium oxide and aluminum are wave long microwave dielectric materials. And due to the high insulating property and high mechanical liability, aluminum can be used as a material for electronic packaging. The porcelain is an insulating ceramics. And titanium oxide, zinc oxide, chrome oxide, tungsten oxide, tin oxide, copper oxide, nickel oxide, normally the doped form of these materials are semiconducting ceramics. Thus, these materials can be used as an active material for gas sensors. The tinned doped indium oxide, ITO, aluminum doped zinc oxide, AZO, are conductive ceramics. Thus, this material are widely used for transparent electrode for display devices. And YBCO, yttrium barium copper oxide is an superconducting ceramics. And doped zirconia and doped lanthanum gallium oxide are ion conducting ceramics, which can be used as an electrolyte material for solid oxide fuel cell the by generation of oxygen vacancies. And the combination of barium strontium oxide and iron oxide is an hard magnetic material, which can be used to pair permanent magnetic material. And zinc manga cobalt magnesium iron oxide is the soft magnetic material and gamma iron oxide is a material for the recording media. And amorphous silica is a glass and doped silica is a material for the fiber optics. And YAG, the yttrium aluminum garnet and chrome doped alumina, the ruby, that can be used as a source material for a laser. The cordierite magnesium iron aluminum silicon aluminum oxide can be used as catalytic surface support for a vehicle due to their very low and sometimes negative value of thermal expansion coefficient. And due to the high insulating property and good mechanical liability, alumina can be used as a material for spark plug. And silica particle can be used as an additive for tires. And normally the nitride and carbide good mechanical strength, so titanium nitride and silicon aluminum oxynitride, SiALON, can be used as the coating material for cutting tools. And diamond silicon carbide alumina are abrasive materials. And PZT is also used as a active material for ultrasonic imaging. And porcelain, the partially stabilized zirconia and alumina is a material for dentistry. And due to the similarity in composition with the natural bone, hydroxyapatite can be used as implant material. The fiber form of several oxide such as alumina silica zirconia are some insulating material. And the combination of alumina silica chromia oxide and magnesium makes the refractory ceramics. And due to the high thermal conductivity, aluminum nitride and boron nitride can be used as a heat sink material. And clays, alumina silica, glass, diamond, ruby, cubic zirconia, they can be used as domestic usage, such as a tires, sanitary ware, whiteware, kitchenware, potter, art, and jewelry. The ceramics can also be classified by their uses. The whiteware bricks are clay product and bricks for high temperatures are refractories, and sandpapers and materials for cutting and polishing are abrasive ceramics. And ceramics also included the cement, glasses, structural ceramics, and advanced ceramics. Ceramics can also be clarified into two categories according to their atomic arrangement. The first one is crystalline solid and second one is amorphous solid. Crystalline solid, the left side figure shows the atomic arrangement of crystalline silica and right side figure shows the atomic arrangement in amorphous silica. So in this like crystalline solid you can find long-range ordering and also find short-range ordering, but in our amorphous silica you can only find short-range ordering structure. So the one keyword for defining the amorphous silica is short-range order. So then let's think about the glass transition. This figure shows the temperature dependent volume change which can be found in silica. From the liquid we can fabricate two different types of solid, one is glass and the other one is crystalline silica. And if we use the very slow cooling process, so we can fabricate the crystalline silica from liquid because during the cooling the atoms can be located at lowest energy position, that makes the crystalline silica solid. Then we can find all of the change in volume in crystalline phase that that temperature is melting temperature. But if the cooling rates and viscosity of liquid is sufficiently large to maintain the amorphous process structure even in solid phase, we can fabricate glasses. So the transition temperature from liquid to glass is the glass transition temperature. The ceramics can also be classified according to their crystallography. So, you know the long-range ordering is the important characteristic feature of crystalline phase, the arrayed atoms in a three-dimensional pattern and this is repeats. The unit cell is the smallest repeated region in space. So as shown here, you can find 7 to 14 unit cell shape with crystal system. First one is the cubic. The cubic structure has the exactly same three the lattice constants apc, and the angle that this is the angle between primitive transition, the vectors, the alpha beta gamma is exactly 90 degree. So compared with cubic, the rhombohedral structure have the different angle with 90 degree. And compared with the cubic face, the tetragonal face has the different lattice constant c. And compared with the tetragonal, hexagonal face the different the angle of gamma is 120 degree. And compared with the cubic face, orthorhombic face have the three different lattice constant a, b, and c. And monoclinic, compared with the orthorhombic face just the difference between orthorhombic face is the different value of angle beta. In triclinic, the triclinic has three different lattice parameter and three typical difference angle, alpha, beta, gamma. And you can find 14 Bravais lattices in this figure. So you can find simple structure in seven unit cell shapes, but the body centered shape can only be found in cubic, tetragonal, and orthorhombic. And face-centered structure can be found in cubic and orthorhombic. And then base-centered structure can only be found in orthorhombic and monoclinic. Then finally, ceramics can be classified according to their microstructure. So there are two different types of ceramics, one is single crystal and the other one is polycrystalline solid. The single crystal is the perfect, periodic, and repeated arrangement atoms, however, the polycrystalline solid is the collection of many single crystal grains. So this figure shows us the schematic diagram for the microstructure of a polycrystalline solid and you can find different unit cell orientation in grain A and grain B. And the interface between grain is grain boundaries. The in this lecture we briefly reviewed the classification of ceramics. In the next we are talking about the material science at the nanoscale because the nanostructuring is one of the important [INAUDIBLE] to develop the novel inorganic materials. Thank you.
