Exercises
17
Figure 3 – Representation of unit cell
of ideal perovskite structure ABO 3 .
Strontium and lanthanum occupy the A sites and manganese occupies
the B sites.
2 Keeping the stoichiometry satisfied, complete each of the following
reactions:
xSrO + LaMnO 3 $ …
(1)
xSrO + (1−x)LaMnO 3 $ …
(2)
xSrO + La 1−x MnO 3−1.5x $ …
(3)
2 For each case, give the normal structure elements and the point defects.
2 Calculate the reagent masses required to prepare 10 g of the solid
solution La 0.84 Sr 0.16 MnO 2.92 from dehydrated lanthanum nitrate,
manganese nitrate, and strontium carbonate.
Data
Elements
La
Sr
Mn
C N O
Molar mass [g mol
-1
] 138.92 87.63 54.95 12 14 16
2 Cite an application of this material.
c. Manganese is present in the solid solution La 1−x Sr x MnO 3−x/2 in the ionic
forms Mn
2+
, Mn
3+
, and Mn
4+
.
2 Use Kroger-Vink notation to express the disproportionation equilibrium involving these species.
2 Express the equilibrium of the solid solution with gaseous oxygen
involving only the manganese and the oxygen.
2 By considering the atomic and electronic defects, give the expression
$
%
2