Fundamentals of Perovskite Oxides

Synthesis, Structure, Properties and Applications

Gibin George, Sivasankara Rao Ede, Zhiping Luo

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000195729
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Clinical Chemistry

This textbook entitled Fundamentals of Perovskite Oxides: Synthesis, Structure, Properties and Applications summarizes the structure, synthesis routes, and potential applications of perovskite oxide materials. Since these perovskite-type ceramic materials offer opportunities in a wide range of fields of science and engineering, the chapters are broadly organized into four sections of perovskite-type oxide materials and technology.

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• Covers recent developments in perovskite oxides

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• Serves as a quick reference of perovskite oxides information

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• Describes novel synthesis routes for nanostructured perovskites

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• Discusses comprehensive details for various crystal structures, synthesis methods, properties, and applications

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• Applies to academic education, scientific research, and industrial R&D for materials research in real-world applications like bioengineering, catalysis, energy conversion, energy storage, environmental engineering, and data storage and sensing

This book serves as a handy and practical guideline suitable for students, engineers, and researchers working with advanced ceramic materials.

1 Introduction to Perovskites

Perovskites have been an important class of materials, exhibiting unusual promising functionalities in various transport and physical properties over other traditional ceramic or composite materials. They have received extensive attention more recently in the fields of materials science, physics, chemistry, geology, and engineering. In this chapter, we give a brief introduction to perovskites regarding their history, formation, and classification.

1.1 History of Perovskites

The term perovskite originated from the mineral perovskite (CaTiO₃) named after the Russian mineralogist Mr. Lev Alekseyevich von Perovski (1792–1856) (Liu et al. 2017). A photo of the CaTiO₃ mineral is shown in Figure 1.1. Nowadays, perovskites represent a wide class of materials with similar or derived crystal structure as that of CaTiO₃ with a general formula ABX₃, as shown in Figure 1.2. In the structure of perovskites, A and B are cations and X is the anion, and A cations are larger than B cations (Figure 1.2a). Six X anions form an octahedron covering the smaller cation B (Figure 1.2b). Therefore, this perovskite lattice is formed by such apex-connected octahedra with A cations between them (Figure 1.2c).

FIGURE 1.1 A photo of CaTiO₃ mineral. (From https://en.wikipedia.org/wiki/Perovskite.)

FIGURE 1.2 Perovskite ABX₃ lattice. (a) Large A and small B cations, with X anions; (b) octahedron by X anions; (c) octahedra lattice.

Often A-site ion provides the structural integrity to the perovskite structure, and B-site ion determines the properties. CaTiO₃ crystallizes into an orthorhombic structure; however, the ideal perovskite structure belongs to the cubic space group $Pm\overline{3}m$ (No. 221). Apart from CaTiO₃, many naturally existing minerals adopt a perovskite structure, for instance, ilmenite (FeTiO₃), MgSiO₃, etc. The silicate perovskites containing Mg, Ca, and Fe are assumed as the most abundant solid phase in the earth’s lower mantle at 670–2,900 km from the surface. Moreover, MgSiO₃ is stable above 23 GPa (Zhang et al. 2014), and the same is believed to constitute the big planets other than Mars (Umemoto et al. 2006). Many perovskite materials exhibit exceptional properties such as high absorption coefficient, long-range ambipolar charge transport, low exciton-binding energy, high dielectric constant, and ferroelectric properties.

BaTiO₃ is the first manmade perovskite synthesized during World War II in 1941; however, it’s naturally existing counterpart benitoite is an extremely rare mineral. BaTiO₃ was used as a ferroelectric and piezoelectric material for a wide range of applications (Eshita et al. 2014). Its application as a piezoelectric material is later replaced by lead zirconate titanate Pb(Zr, Ti)O₃, another important perovskite. Similarly, SrTiO₃ is the first insulator, and the first oxide reported as superconductive below 0.35 K. Even though SrTiO₃ was synthesized in the 1950s, its natural counterpart was discovered in 1982. SrTiO₃’s first-ever use was as a simulant for diamond due to its resemblance to a diamond, but the softness and high cost resulted in their replacement with other simulants such as yttrium aluminum garnet (YAG), gadolinium gallium garnet (GGG), and cubic zirconia.

1.2 Formation of Perovskites

Since the discovery of BaTiO₃, a large number of perovskites with general formula ABO₃ have been synthesized and studied for their unique properties pertaining to the presence of two different cations in their lattice. In general, the new perovskite structured materials possess a wide range of properties such as optical, magnetic, thermoelectric, piezoelectric, photochemical, thermochromic, electrochromic, and electrochemical, which are not observed in their ancestors. Besides the general physical and chemical properties, these materials are extensively studied for their applicability as electrode materials for energy storage and scavenging, e.g., LaMnO₃, Ba_0.5Sr_0.5Co_0.8Fe_0.2O₃, etc. Despite the low-cost and ea...