Perovskite and Oxide Synthesis by Spray Pyrolysis Thomas

Perovskite and Oxide Synthesis by Spray Pyrolysis Thomas Graule Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, CH Thomas. graule@empa. ch

content • principle spray pyrolysis • spray pyrolysis test facility at EMPA • composition and morphology

why spray pyrolysis? • demands on ceramic powder fabrication for SOFCs: – – controlled composition (including impurity content) continous production process controlled and reproducible powder morphology cost effective production lines • spray pyrolysis: Ý easy control of the composition in a salt solution Ý suited for continous production Ý control of composition and morphology of the ceramic particles in one single preparation step ß off-gas treatment

principle spray pyrolysis precursor spray pyrolysis heat treatment spray drying salt (nitrate) solution evaporation precipitation decomposition sintering calcination granulation composition morphology

spray pyrolysis test facility at EMPA

typical spray pyrolysis conditions • • • solutions (nitrates) : flow rate : air pressure rate : ultra sonic frequency : furnace temperature : almost saturated solution ca. 30 ml/min 2 bar 40 MHz 450 - 500 °C Þ yields powders of 4 - 6 g/min, 2 -3 kg/day (8 h) Þ limitations: – water evaporation – furnace power, flow rate, water content in precursor solution

preparation of Lax. Ca 1 -x. Fey. Co 1 -y. O 3 sintered granulate 1100°C 1000°C 800°C

morphology of La(Sr)Mn. O 3 sprayed grains agglomerate size: 20 - 80 micron crystallite size: < 0. 5 micron

morphology of La(Sr)Mn. O 3 sprayed and sintered LSM grains prepared by spray pyrolysis agglomerate size: 10 -20 (50) micron crystallite size: 2 -5 micron

summary • present experience: – phase pure perovskites have been prepared • Examples: (Lax. Sr 1 -x)y. Mn. O 3, (Lax. Ca 1 -x)(Fey. Co)1 -y. O 3 • homogenous powder morphology – production rate is up to 3 kg/per day • the method is generally applicable to oxide and non oxide ceramics • tailoring of powder morphology by spray pyrolysis parameters and powder processing after the preparation process • suspensions of YSZ added to the precursor solution can be used