Preface

The primary classes of solid materials are ceramics, metals, and polymers. Ceramics are nonmetallic materials and can be divided into two classes: traditional and advanced. Tradi‐ tional ceramics include clay products, silicate glass, and cement, while advanced ceramics consist of carbides (SiC), pure oxides (SnO2), rare earth oxides (REOs), and many others. Ce‐ ramic materials display a wide range of properties, which facilitate their use in many differ‐ ent product areas compared with other materials. Ceramic oxides can also be used as protection coatings because of their interesting corrosion-inhibiting properties. This book is a compilation of laboratory experiences in the sequential phases of advanced ceramic proc‐ essing and analysis. Although not in the style of a handbook, in a real sense, it is a guide and manual to some practical aspects excluded from other available sources. Researchers from several disciplines across the continents share their expertise and research knowledge about advanced preparation techniques for ceramic oxides.

**In Chapter 1, Microwave Fast Sintering of Double Perovskite Ceramic Materials**, Adel A.M. Mohamed's team focused on fabrication of the double perovskite La2MMnO6 (M = Ni, Co) ceramics using the microwave sintering technique, in order to further improve their magnetic and dielectric properties for practical spintronic applications. As a result, the mi‐ crowave sintering approach shows obviously better promise over the conventional heating method, in terms of higher efficiency of heating, significantly shorter reaction time, smaller and more regular size, and stronger magnetization of the products. IR, XRD, and SEM-EDX analyses confirmed the formation of single phase for La2MMnO6 (M = Ni, Co) double perov‐ skites.

**In Chapter 2, New Approaches to Preparation of SnO2-Based Varistors: Chemical Synthe‐ sis, Dopants, and Microwave Sintering**, Maria A. Zaghete's team provided a review on new processing steps for the production of SnO2 varistors and showed the possibility to get electrical properties with nonohmic characteristics for technological applications. The new approaches for the chemical synthesis of ceramic powder promote the homogeneous distri‐ bution of dopants into the ceramic matrix and reduce segregation and the formation of sec‐ ondary phases, which are harmful factors on the electrical properties of the varistor and facilitate the integration of the material in today's electronic devices for electrical protection. As a result, the use of microwave oven is a new processing step aiming to reduce the time and temperature of the sintering step and can be considered a promising procedure for va‐ ristor production. The preparation of varistors as film emerges as a new possibility in order to facilitate the integration of this material in electronic circuits.

**In Chapter 3, Porous Ceramics**, Naboneeta Sarkar and Ik Jin Kim used a foaming method, a simple and versatile approach, as fabrication techniques for porous ceramics with tailored

microstructure, along with distinctive properties. The effects of foam precursor suspensions – bubble size, distribution, contact angle, and surface tension – on the resultant porous ce‐ ramics' mechanical and physical properties are assessed in this chapter. Control of these pa‐ rameters can allow the tailoring of the microstructures of porous ceramics produced by direct foaming.

**In Chapter 4, Electrochemical Synthesis of Rare Earth Ceramic Oxide Coatings**, Teresa D. Golden's team discussed in detail the electrolytic and direct electrodeposition for the pro‐ duction of rare earth oxide coatings, such as gadolinium, terbium, samarium, neodymium, europium, and dysprosium oxides. Direct electrodeposition occurs when there is a direct oxidation or reduction (exchange of electrons) between the metal ion or metal ion complex and electrode to produce the metal oxide on the surface. The physical and chemical proper‐ ties of the electrodeposited oxides were characterized by XRD, SEM, and XPS techniques. The mechanisms of electrodeposition for rare earth oxides are discussed in detail. As a re‐ sult, a variety of morphologies have been obtained for the REO films, such as nanocrystal‐ line films, nanorods, nanotubes, nanosheets, as well as flower-like and coral-like nanostructures.

**In Chapter 5, Thermal Barrier Coatings: An Overview**, Sumana Ghosh provided an over‐ view on the thermal barrier coating (TBC) requirement, application of TBCs, degradation mechanisms, different processing techniques used for preparation of TBCs, and their ther‐ mal properties. As a result, TBCs are required to be more suitably designed for the thermal protection of gas turbine engine components to increase engine operating temperatures, fuel efficiency, and engine reliability significantly. However, coating durability is a vital factor to increase the engine operating temperature. Therefore, the coating behavior and failure modes under high temperature and high thermal gradient cyclic conditions should be prop‐ erly understood to develop next-generation advanced TBCs.

**In Chapter 6, Electrocaloric Properties of PLZT and BaTiO3 Ceramics**, Hiroshi Maiwa stud‐ ied the electrocaloric temperature change of the PLZT ceramics and BaTiO3 ceramics using direct measurements. The electrocaloric effect (ECE) is a phenomenon in which a material shows a reversible temperature change under an applied electric field. He concluded that the possibility of the approximately twice temperature change was obtained by introducing 9.1% La components in PZT ceramics.

> **Adel Mohamed** Qatar University, Qatar
