Self-Nanostructuring in SrTiO3: A Novel Strategy for Enhancement of Thermoelectric Response in Oxides

被引：62

作者：

Azough, Feridoon ^{[1
]}

Gholinia, Ali ^{[1
]}

Alvarez-Ruiz, Diana T. ^{[1
]}

Duran, Ercin ^{[1
]}

Kepaptsoglou, Demie M. ^{[2
,3
,4
]}

Eggeman, Alexander S. ^{[1
]}

Ramasse, Quentin M. ^{[2
,5
]}

Freer, Robert ^{[1
]}

机构：

[1] Univ Manchester, Sch Mat, Manchester M13 9PL, Lancs, England

[2] SuperSTEM Lab, STFC Daresbury Campus, Daresbury WA4 4AD, Cheshire, England

[3] Univ York, Jeol Nanoctr, York YO10 5DD, N Yorkshire, England

[4] Univ York, Dept Phys, York YO10 5DD, N Yorkshire, England

[5] Univ Leeds, Sch Chem & Proc Engn, Leeds LS2 9JT, W Yorkshire, England

来源：

ACS APPLIED MATERIALS & INTERFACES | 2019年 / 11卷 / 36期

基金：

英国工程与自然科学研究理事会;

关键词：

nanostructuring; thermal conductivity; strontium titanate; oxide thermoelectric; perovskite; aberration corrected microscopy; 3D electron diffraction; TRANSMISSION ELECTRON-MICROSCOPY; TILT GRAIN-BOUNDARY; COMBUSTION SYNTHESIS; DISLOCATION CORES; HIGH-TEMPERATURE; LA; PERFORMANCE; FIGURE; MERIT; BULK;

D O I：

10.1021/acsami.9b06483

中图分类号：

TB3 [工程材料学];

学科分类号：

0805 ; 080502 ;

摘要：

Nanostructuring is recognized as an efficient route for enhancing thermoelectric response. Here, we report a new synthesis strategy for nanostructuring oxide ceramics and demonstrate its effectiveness on an important n-type thermoelectric SrTiO3. Ceramics of Sr0.9La0.1TiO3 with additions of B2O3 were synthesized by the mixed oxide route. Samples were sintered in air followed by annealing in a reducing atmosphere. Crystallographic data from X-ray and electron diffraction showed Pm3_m cubic symmetry for all the samples. High-resolution transmission electron microscopy (HRTEM) showed the formation of a core-shell type structure within the grains for the annealed ceramics. The cores contain nanosize features comprising pairs of nanosize voids and particles; the feature sizes depend on annealing time. Atomic-resolution, high-angle annular-dark-field imaging and electron energy loss spectroscopy in the scanning transmission electron microscopy (STEM-HAADF-EELS) showed the particles to be rich in Ti and the areas around the voids to contain high concentrations of Ti3+. Additionally, dislocations were observed, with significantly higher densities in the shell areas. The observed dislocations are combined (100) and (110) edge dislocations. The major impact of the core-shell type microstructures, with nanosize inclusions, is the reduction of the thermal conductivity. Sr0.9La0.1TiO3 ceramics containing grain boundary shells of size >> 1 mu m and inclusions in the core of 60-80 nm exhibit a peak power factor of 1600 mu W/m.K-2 at 540 K; at 1000 K, they exhibit a low thermal conductivity (2.75 W/m.K) and a power factor of 1050 mu W/m.K-2 leading to a high of ZT of 0.39 & PLUSMMN; 0.03. This is the highest ZT reported so far for Sr0.9La0.1TiO3 based-compositions. This nanostructuring strategy should be readily applicable to other functional oxides.

引用

页码：32833 / 32843

页数：11