Thermoelectric Behavior of Samarium Doped CaMnO3 Perovskite.

Emission of greenhouse gases in the process of combustion of fossil fuel to generate energy is a major threat to the planet earth due to global warming. The combustion processes also result in a sizeable amount of heat that gets wasted. Our energy demand will continue to increase by 30- 40% by the next 20 years. An eco-friendly technology is the need of the hour to tackle the waste heat expelled into the atmosphere and to keep greenhouse gases under check. Thermoelectricity deals with the conversion of heat into electricity. Being an eco-friendly technique, numerous researches are ongoing in the field of thermoelectric generation to convert the wasted heat into useful electricity. Among wide varieties of thermoelectric materials, oxide thermoelectric materials are advantageous due to its structural and chemical stability at high-temperature region. The current study is based on the enhancement of the electrical conductivity of CaMnO₃ perovskite by the trivalent substitution of Sm3+ at the Ca2+ site. A higher valent substitution at the A site of a CaMnO₃ will induce Mn³⁺ ions in the Mn⁴⁺ matrix that will lead to a Jahn-Teller distortion and thereby increase the conductivity. A two order increase in the electrical conductivity was observed for Sm_0.1Ca_0.9MnO₃ at 573 K than that of pure CaMnO₃. A maximum value of ZT obtained is 0.095 at 1073 K for Sm_0.05Ca_0.95MnO₃, which is higher than the reported values of Lanthanum and Yttrium doped Calcium Manganate. [ABSTRACT FROM AUTHOR]