Ruddlesden-Popper structured BaLa2Ti3O10, a highly anisotropic material for thermal barrier coatings

BaLa2Ti3O10 (BLT) with Ruddlesden-Popper structure is investigated as a material for thermal barrier coatings (TBCs). BLT shows excellent sintering resistance and remains phase stability at 1500 degrees C for 110 h. After annealing at 1500 degrees C for 1 h, BLT bulk material exhibits c-axis textured structure with c-axis parallel to the hot pressing direction. Thermal expansion coefficients of BLT in a-b plane are in the range of 9.5 x 10(-6)-11.3 x 10(-6) K, those along c-axis range from 10.4 x 10(-6) to 12.1 x 10(-6) K-1, which are comparable to those of 8YSZ. The thermal conductivities of BLT in a-b plane and along c-axis are 1.41-1.71 and 1.31-1.60 W/mK, respectively, nearly 20% lower than those of 8YSZ. The anisotropy in thermo-physical properties is attributed to the insertion of weakly bonded Ba-O layer in the BLT crystal. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.