The perovskite structure is very versatile in terms of accommodating An+ and Bm+ cations. Furthermore, perovskite structures are utilized for a very wide range of applications. a) Provide a drawing of a perovskite structure in the provided unit cell below. Clearly label the An+, B+ and XP ions. Z A b) What is the coordination number for the An+ cation (i.e. AXy) in the ideal cubic perovskite structure? c) What is the coordination number for the Bm+ cation (i.e. BX2) in the ideal cubic perovskite structure? The Goldschmidt tolerance factor for the BaTiO3 perovskite phase is 1.04 using the following ionic radii r(Ba²+) (VI) = 1.61Å, r(T+) (VI) = 0.605 Å and r(02) (VI) = 1.40Å. Because the tolerance factor is larger than 1.00 the compound is ferroelectric, i.e. a large net dipole moment is generated in an external electric field. d) What ion causes the ferroelectric response in BaTiO3? What happens to this ion to cause a ferroelectric response? e) Starting with BaTiO3, what kind of atomic/ionic substitution (i.e. replacement) would you carry out in order to make a non-ferroelectric perovskite phase. You need to use the periodic table for that and employ the systematic changes across the periodic table to design this non-ferroelectric material. While the majority of perovskite phases are oxides and halides recently new hydride based perovskites (ABH3) have been reported. Those phases have hydride (H) anions and the B-cations are lithium cations. Using different ratios of divalent and monovalent cations in the A-site generates vacancies on the hydride lattice. It turns out that those phases are excellent hydride anion conductors. Determine the composition of Ba(1-x)KxLiH-s with 4% vacancies on the hydride sublattice. Write down a balanced equation for the formation of Ba(1-x)K+LiH3-s with 4% hydride vacancies. You can use the binary hydrides (barium hydride, potassium hydride and lithium hydride) as starting materials. g) Calculate the masses (in grams) of all starting materials required for the preparation of 14 grams of that material.

The perovskite structure is very versatile in terms of accommodating An+ and Bm+ cations. Furthermore, perovskite structures are utilized for a very wide range of applications. a) Provide a drawing of a perovskite structure in the provided unit cell below. Clearly label the An+, B+ and XP ions. Z A b) What is the coordination number for the An+ cation (i.e. AXy) in the ideal cubic perovskite structure? c) What is the coordination number for the Bm+ cation (i.e. BX2) in the ideal cubic perovskite structure? The Goldschmidt tolerance factor for the BaTiO3 perovskite phase is 1.04 using the following ionic radii r(Ba²+) (VI) = 1.61Å, r(T+) (VI) = 0.605 Å and r(02) (VI) = 1.40Å. Because the tolerance factor is larger than 1.00 the compound is ferroelectric, i.e. a large net dipole moment is generated in an external electric field. d) What ion causes the ferroelectric response in BaTiO3? What happens to this ion to cause a ferroelectric response? e) Starting with BaTiO3, what kind of atomic/ionic substitution (i.e. replacement) would you carry out in order to make a non-ferroelectric perovskite phase. You need to use the periodic table for that and employ the systematic changes across the periodic table to design this non-ferroelectric material. While the majority of perovskite phases are oxides and halides recently new hydride based perovskites (ABH3) have been reported. Those phases have hydride (H) anions and the B-cations are lithium cations. Using different ratios of divalent and monovalent cations in the A-site generates vacancies on the hydride lattice. It turns out that those phases are excellent hydride anion conductors. Determine the composition of Ba(1-x)KxLiH-s with 4% vacancies on the hydride sublattice. Write down a balanced equation for the formation of Ba(1-x)K+LiH3-s with 4% hydride vacancies. You can use the binary hydrides (barium hydride, potassium hydride and lithium hydride) as starting materials. g) Calculate the masses (in grams) of all starting materials required for the preparation of 14 grams of that material.

Principles of Modern Chemistry

8th Edition

ISBN:9781305079113

Author:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler

Publisher:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler

Chapter21: Structure And Bonding In Solids

Section: Chapter Questions

Problem 42P

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