參雜過渡金屬離子之二氧化鈰電解質燒結性能和電性表現研究

Investigation on Sintering and Electrical Conductivity of Ceria-based Materials by Addition of Multiple Metal Oxides

楊庭懿(Ting-Yi Yang)

指導教授 ： 韋文誠

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201901627

摘要

本研究旨在研究釤、錳、鐵共摻雜二氧化鈰基電解質材料合成、燒結及電性劣化的行為。首先，二氧化鈰基材料為透過乙二胺四乙酸-檸檬酸法製備釤錳鐵共摻雜二氧化鈰(Ce0.9Sm0.1O2 和Ce0.9Sm0.09 Fe0.005Mn0.005O2，分別簡稱ST00及S9HH)樣品，經X光繞射分析得知均生成單一立方螢石結構，未有第二相析出，而且在1250 ℃持溫5小時完成燒結 (高於99%相對密度)。此外，利用兩點性電性量測和阻抗分析，了解電性表現和離子導電機制。二氧化鈰基電解質的電性和溫度倒數呈現線性關係。得知S9HH於空氣環境下800 ℃之導電性為7.15*10-2 S•cm-1，高於未添加錳鐵者(ST00)。ST00和S9HH的活化能皆在1.10到1.20 eV之間，推斷皆為以氧空缺交換氧離子擴散為主要導電機制。在650 °C長時間的電性穩定性測試方面，顯示釤錳鐵共摻雜二氧化鈰經長時間老化，電性表現(3.11*10-2 S•cm-1)仍高於原始製備的釤共摻雜二氧化鈰ST00(2.60*10-2 S•cm-1)。研究指出添加鐵錳元素後能有效提升短時(short-term)高溫導電性，而長時間(long-term)電性劣化來自晶界漸次產生的高Sm的螢石相微晶，非由超晶格的氧空缺所造成。

關鍵字

固態氧化物燃料電池 ； 二氧化鈰 ； 微結構 ； 電性 ； 時效

並列摘要

Ceria-based electrolyte materials are synthesized by an EDTA-citric acid method. Two samples, Ce0.9Sm0.1O2 (ST00) and Ce0.9Sm0.09Fe0.005Mn0.005O2 (S9HH) are prepared and sintered to single cubic fluorite structure and still kept within solution limit. The microstructure and electrical properties are analyzed, showing S9HH having >99% theoretical density (T.D.) observed by SEM after sintered at 1250 ℃ for 5 hr, and suitable for an electrolyte of solid oxide fuel cell. Bulk electrical conductivity of S9HH and ST00 is a liner relationship to the reverse of the temperature (1/T). The bulk electrical conductivity of S9HH samples is 7.15*10-2 S•cm-1 higher than that of ST00 samples 2.60*10-2 S•cm-1 at 800 ℃. Both of the activation energy of ceria-based materials are around 1.10-1.20 eV, indicating the same conductivity mechanism by oxygen vacancy/ion exchange and diffusion. After an aging treatment at 650 ℃ for a holding time of 500 h, the electrical conductivity of S9HH reduces to 3.11*10-2 S•cm-1, but still higher than that of ST00 1.60*10-2 S•cm-1 at 800 ℃. The electrical conductivity degradation in long-term aging is because of the formation of continues Sm-rich fluorite sub-micro grains.

並列關鍵字

SOFCs ； CeO2 ； microstructure ； electrical conductivity ； aging

參考文獻

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