Preparation of La₂(Ce_xZr_1-x)₂O₇ Nano-Porous Powders via Citric Acid Derived Sol-Gel Processing

Abstract:

La₂(Ce_xZr_1-x)₂O₇ powders were synthesized by the Pechini routine with citric acid as a chelating agent. TG-DTA, XRD and SEM were used to characterize as-prepared powders. Experimental results show that the crystalline structures of La₂(Ce_xZr_1-x)₂O₇ transform to cubic fluorite phase with Ce substitution for Zr from x=0.1 to 1.0, no longer keeps the cubic pyrochlorite structure of La₂Zr₂O₇. La₂(Ce_xZr_1-x)₂O₇ powders present nanoporous low-density microstructurally, and successively lump-like, fluff-like and cotton-like morphologically with the increase of citric acid addition, this typical nanoporous microstructure results from a pore-crating mechanism initiated by self-propagation reactions between citric acids and nitrates. It is shown that the thermal conductivity k of powder compacts decreases sharply down from 1/10 to 1/32 of that of its single crystal bulk. as compact porosity increases from 60% to 95%. Therefore thermal barrier coatings (TBCs) of La₂(Ce_xZr_1-x)₂O₇ with such nanoporous structures by an appropriate processing may work with quite a high insulative performance and very promising for TBC applications of high-efficiency and large propulsion engines.

• Periodical: Advanced Materials Research (Volume 833)
• Pages: 197-201
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.833.197
• Online since: November 2013
• Authors: Lu Zheng, Jian Qiu Guo, Liang Bin Liu, Yin Xin Tang, Yu Zhong Guo
• Keywords: La₂(Ce_xZr_1-x)₂O₇, Nano-Porous Powders, Sol-Gel Processing, Thermal Barrier Coating (TBC), Thermal Conductivity (TC)

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