Publication Date:
2015-02-19
Description:
The effect of substitution and oxidation-reduction on the thermal conductivity of perovskite-like layered structure (PLS) ceramics was investigated in relation to mass contrast and non-stoichiometry. Sr (acceptor) was substituted on the A site, while Ta (donor) was substituted on the B site of La 2 Ti 2 O 7 . Substitution in PLS materials creates atomic scale disorders to accommodate the non-stoichiometry. High resolution transmission electron microscopy and X ray diffraction revealed that acceptor substitution in La 2 Ti 2 O 7 produced nanoscale intergrowths of n = 5 layered phase, while donor substitution produced nanoscale intergrowths of n = 3 layered phase. As a result of these nanoscale intergrowths, the thermal conductivity value reduced by as much as ∼20%. Pure La 2 Ti 2 O 7 has a thermal conductivity value of ∼1.3 W/m K which dropped to a value of ∼1.12 W/m K for Sr doped La 2 Ti 2 O 7 and ∼0.93 W/m K for Ta doped La 2 Ti 2 O 7 at 573 K.
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics
Permalink