Pulverized FeS₂ (pyrite) gives different discharge test results with as-received FeS₂ electrodes. The as-received FeS₂ electrode shows three voltage plateaus during the discharge test. However, the ball-milled FeS₂ electrode shows two voltage plateaus. To interpret this result, the effect of FeS₂ particle size on electrochemical reactions is investigated by unit cell discharge tests, SEM and XRD. As a result, it is found that the transition reaction product (Li₂ + xFe + xS₂) of FeS₂ explains the difference. The as-received FeS₂ reacts according to three reaction steps (FeS₂ → Li₃Fe₂S₄ → Li₂ + xFe₁ + xS₂ → LiFe₂S₄). However, ball-milled FeS₂ reacts without the Li₂ + xFe₁ + xS₂ stage. In this study, this result is explained by the difference in electrochemical reaction mechanism. The as-received FeS₂ has a larger radius than the ball-milled FeS₂. Therefore, the lithium ion has to diffuse into the FeS2 unreacted core, and Li₂ + xFe₁ + xS₂, the transition reaction product of as-received FeS₂, is formed during this stage.

The effects of ZnO coating on the sensing properties of CNT:ZnO based gas sensors were studied for H2S gas. The nano ZnO sensing materials were grown by hydrothermal reaction method. CNT:ZnO was prepared by ball-mill method. The mole range of nano ZnO coating on CNT surface was from 0 to 10%. The CNT:ZnO gas sensors were fabricated by a screen printing method on alumina substrates. The structural and morphological properties of the CNT:ZnO sensing materials were investigated by XRD, EDS, SEM and TEM. The XRD patterns showed that CNT:ZnO powders with hexagonal structure were grown with (002) dominant peak. The diameter of CNT from TEM was about28 nm.