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Ca‐doped rare earth perovskite materials for tailored exsolution of metal nanoparticles
Author(s) -
Lindenthal Lorenz,
Ruh Thomas,
Rameshan Raffael,
Summerer Harald,
Nenning Andreas,
Herzig Christopher,
Löffler Stefan,
Limbeck Andreas,
Opitz Alexander Karl,
Blaha Peter,
Rameshan Christoph
Publication year - 2020
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520620013475
Subject(s) - dopant , doping , materials science , perovskite (structure) , metal , oxide , nanoparticle , catalysis , crystal structure , chemical engineering , nanotechnology , crystallography , chemistry , metallurgy , optoelectronics , biochemistry , engineering
Perovskite‐type oxide materials (nominal composition AB O 3 ) are a very versatile class of materials, and their properties are tuneable by varying and doping A ‐ and B ‐site cations. When the B ‐site contains easily reducible cations ( e.g. Fe, Co or Ni), these can exsolve under reducing conditions and form metallic nanoparticles on the surface. This process is very interesting as a novel route for the preparation of catalysts, since oxide surfaces decorated with finely dispersed catalytically active (often metallic) nanoparticles are a key requirement for excellent catalyst performance. Five doped perovskites, namely, La 0.9 Ca 0.1 FeO 3–δ , La 0.6 Ca 0.4 FeO 3–δ , Nd 0.9 Ca 0.1 FeO 3–δ , Nd 0.6 Ca 0.4 FeO 3–δ and Nd 0.6 Ca 0.4 Fe 0.9 Co 0.1 O 3–δ , have been synthesized and characterized by experimental and theoretical methods with respect to their crystal structures, electronic properties, morphology and exsolution behaviour. All are capable of exsolving Fe and/or Co. Special emphasis has been placed on the influence of the A ‐site elemental composition on structure and exsolution capability. Using Nd instead of La increased structural distortions and, at the same time, hindered exsolution. Increasing the amount of Ca doping also increased distortions and additionally changed the Fe oxidation states, resulting in exsolution being shifted to higher temperatures as well. Using the easily reducible element Co as the B ‐site dopant significantly facilitated the exsolution process and led to much smaller and homogeneously distributed exsolved particles. Therefore, the Co‐doped perovskite is a promising material for applications in catalysis, even more so as Co is catalytically a highly active element. The results show that fine‐tuning of the perovskite composition will allow tailored exsolution of nanoparticles, which can be used for highly sophisticated catalyst design.