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Introduction to Perovskites
Published in Gibin George, Sivasankara Rao Ede, Zhiping Luo, Fundamentals of Perovskite Oxides, 2020
Gibin George, Sivasankara Rao Ede, Zhiping Luo
In terms of perovskite structures, perovskites can be classified as Single perovskites. As shown in Figure 1.7a, the octahedra are identical or randomly distributed, showing no ordering in their structure. The single perovskites adopt a low symmetrical triclinic to high symmetric cubic phases. Single perovskites are the most studied perovskites, and their properties can be easily modified by doping. Single perovskite oxide structures with alkaline earth metal or rare earth metals at the A-site and transition metal at the B-site are the most studied among single perovskites. A list of important single oxide perovskites with different structures and applications are presented in Table 1.1. Unlike complex perovskites, most single perovskites can be synthesized easily at low temperatures using conventional techniques.Double perovskites. As shown in Figure 1.7b, two different types of octahedra produce doubled lattice spacing. Double perovskites with the formula ABBʹX6 are also successfully synthesized following the advantages of ABX3 perovskite structured materials. The presence of two property determining B-site cations is likely to exhibit superior properties than ABX3 perovskite materials, especially among the halide perovskites for optoelectronic applications. Some double perovskite oxides outperform single perovskites in electrocatalysis water splitting and thermoelectric properties par to the commercial noble metal and chalcogen-based materials.Layered perovskites. As shown in Figure 1.7c, the octahedra can form a layered structure. The layered perovskites are further classified as the Ruddlesden-Popper phase, the Dion−Jacobson phase, the Aurivillius phase, and AnBnO3n+2 layered phase. Their structures are described in Chapter 3. The layered perovskites exhibit exceptional characteristics, such as superconductivity, that are not observed in single or double perovskite counterparts, due to the oxygen-rich separating layers between the perovskite slabs. In general, the layered perovskites exhibit anisotropy in their properties along the ab-plane and c-axis.Anion deficient phase, such as the well-known brownmillerite, which is composed of alternating BO6 octahedra and BO4 tetrahedra layers. This structure is described in Chapter 3.Hexagonal perovskites, which possess hexagonal close packing of AX3 layers, instead of cubic close packing of AX3 layers (Fop et al. 2019). More details can be found in Chapter 3.
Perovskite solar cells: must lead be replaced – and can it be done?
Published in Science and Technology of Advanced Materials, 2018
Qi Zhang, Feng Hao, Jianbao Li, Yangying Zhou, Yaxuan Wei, Hong Lin
Transition metals such as CuII [123,124], CrII [125], MnII [126] and FeII [127,128] have been reported to extend significantly the field of synthesis of new perovskites for PV applications, and benefit additionally from physicochemical diversity and high crustal abundance. In contrast to the previously discussed perovskites, initial studies have indicated that because of their smaller ionic radii than Pb and other reported elements, these transition metal–perovskites have a layered structure that is isostructural to compounds of the Ruddlesden–Popper phase, such as K2NiF4.