Creation of heavily La-doped SrTiO3 thermoelectric films achieved by freeze-dry pulsated orifice ejection method and laser powder bed fusion

Achieving both fine grain sizes and high doping levels simultaneously holds great promise for improving the dimensionless figure of merit (zT) of oxide thermoelectric materials; however, this remains a global challenge. This study presents a pioneering example of fabricating heavily La-doped SrTiO 3 films by leveraging the unique characteristics of laser powder bed fusion (L-PBF). A novel freeze-dry pulsated orifice ejection method (FD-POEM) was used to prepare spherical SrTiO 3 –La 2 O 3 composite powders with a narrow size distribution, homogeneous element distribution, and high laser absorptivity. Owing to the high processing temperature and rapid solidification of the L-PBF process, the La 2 O 3 nanoparticles decomposed and dissolved in the lattice of the cubic perovskite SrTiO 3 . Consequently, the thermoelectric SrTiO 3 film achieved a high La doping concentration of 36.7 mol% and a nanoscale grain size of approximately 700 nm, surpassing conventional methods. Moreover, the La-doped SrTiO 3 film, approximately 10 μm thick, was closely deposited onto a Mo substrate and exhibited excellent thermal stability at 1073 K, making it well-suited for high-temperature thermoelectric applications. • Freeze-dry pulsated orifice ejection method (FD-POEM) enables fabrication of spherical SrTiO 3 –La 2 O 3 composite powders for laser powder bed fusion (L-PBF). • Owing to high processing temperature and rapid solidification of the L-PBF process, La-doped SrTiO 3 thermoelectric films simultaneously achieved a higher La doping concentration of 36.7 mol% and a smaller grain size of 0.74 μm compared to conventional methods. • A thermoelectric La-doped SrTiO 3 films were closely deposited onto a pure Mo substrate without observable interface cracks or impurities and exhibited excellent thermal stability at 1073 K, making it suitable for high-temperature applications. • This study demonstrated the feasibility of fabricating heavily doped thermoelectric materials by combining FD-POEM and L-PBF.