Figure 4 shows the FT-IR spectra of the standard KBr
and the samples prepared at 600–1000◦C for 6 hours. The
band around 600 cm−1 corresponds to the stretching mode,
which involves the internal motion of a change in Mn–O–
Mn bond length [14]. This band is related to the environment
surrounding theMnO6 octahedral. For the samples prepared
below 800◦C, the small absorption bands at around 860–
900 cm−1 were observed. These bands correspond to
SrCO3, La2O2CO3 and LaCO3(OH) impurity peaks which
disappeared at higher temperature of thermal decomposition.
The FT-IR results agree well with the XRD results
(Fig. 3).