Characterization Style Guide

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FTIR is used to image chemical bonds in a sample.


Practice

First, a small amount of sample is ground with KBr at a ratio of 1:50 to 1:100. This mixture is then pressed into a thin transparent pellet. If the pellet has opaque regions, too much of the mixture was added to the pellet die.

Next, collect a background spectra on the empty FTIR machine. Background signal can be reduced by purging the system with nitrogen. Load the transparent pellet into the sample holder, and insert the sample holder into the FTIR. Collect the spectra. If signal intensity is too low, repeat the procedure using a higher sample:KBr ratio. Some samples can not be pressed into pellets. For these, ATR-FTIR can be used.

FTIR-ATR testing geometry



Analysis

FTIR peaks correspond to chemical bonds present in the sample. Different chemical bonds have different characteristic regions, as shown in the table below. Peak locations for specific compounds can be located in literature. In this image, the peak at X corresponds to P-O bond and the peak at Y corresponds to the Fe-O bond.

LiFePO4 FTIR Spectra

Equipment Sourcing