Mixed conductivity of garnet phases based on gadolinium ferrite

2004 ◽  
Vol 24 (6) ◽  
pp. 1309-1312 ◽  
Author(s):  
A.L. Shaula ◽  
V.V. Kharton ◽  
F.M.B. Marques
Keyword(s):  
2013 ◽  
Vol 710 ◽  
pp. 33-36
Author(s):  
Jie Zhao ◽  
Jiang Fu ◽  
Yong Fu ◽  
Yong Chang Ma

In order to accelerate the commercialization of SOFCs technology, the key is the development of high performance cathode materials operated at intermediate temperature. Sr and Cu doped rare earth oxide La1-xSrxFe1-yCu.yO3-δ (x=0.1, 0.3 ; y=0.1, 0.2, denoted as LSFCu-11, LSFCu-31 and LSFCu-32 ) were synthesized by solid state reaction method (SSR). The formation process, phase structure and microstructure of the synthesized samples were characterized using TG/DSC, XRD and SEM. The thermal expansion coefficients (TEC) of the samples were analyzed by thermal dilatometry. The electrical conductivities of the samples were measured with DC four-terminal method from 25 to 950 °C. The results indicate that the samples exhibit a single phase with orthorhombic and hexagonal perovskite structure after sintered at 1200 °C for 4h. The electrical conductivity of the samples increases with temperature up to a maximum value, and then decreases gradually. The small polaron hopping is regarded as the conducting mechanism for synthesized samples at T 550 °C. The negative temperature dependence occurring at higher temperature is due to the creation of oxygen vacancies for charge balance. LSFCu-32 has higher mixed conductivity (> 100 S·cm-1) at intermediate temperature and can meet the demand of cathode material for IT-SOFC. In addition, the average TECs of LSFCu-11, LSFCu-31 and LSFCu-32 are 1.22 × 10-6 K-1 , 1.30 × 10-6 K-1 and 1.34 × 10-6 K-1 respectively.


1991 ◽  
Vol 48 (3-4) ◽  
pp. 207-212 ◽  
Author(s):  
Y TERAOKA ◽  
T NOBUNAGA ◽  
K OKAMOTO ◽  
N MIURA ◽  
N YAMAZOE

2018 ◽  
Vol 47 (5) ◽  
pp. 2791-2799 ◽  
Author(s):  
Sevgul Ozturk Koç ◽  
Sezin Galioglu ◽  
Seckin Ozturk ◽  
Burcu Akata Kurç ◽  
Emrah Koç ◽  
...  

2018 ◽  
Vol 281 ◽  
pp. 859-864
Author(s):  
Yan Xing ◽  
Meng Fei Zhang ◽  
Tian Jun Li ◽  
Wei Pan

La2NiO4+σ nanofibers exhibiting typical Ruddlesden–Popper structure (K2NiO4) were fabricated by a facile electrospinning method. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were used to analyze the structure, morphology and crystal process of the La2NiO4+σ nanofibers. For electrical properties measurement, uniaxially aligned nanofibers were directly collected and assembled into electrode. In our research, La2NiO4+σ phase forms above 873K with no impurity phase emerges during the thermal treatments. The nanofibers are smooth and uniform throughout the entire length and the grain is growing as calcination temperature increases. Furthmore, the La2NiO4+σ nanofibers own high mixed conductivity at 773K, laying good foundation for intermediate temperature solid oxide fuel cells application.


2014 ◽  
Vol 989-994 ◽  
pp. 759-762
Author(s):  
Jiang Fu ◽  
Jie Zhao ◽  
Yong Fu ◽  
Rong Rong Li

Multi-elements doped LaCoO3-based mixed conductors La0.7Sr0.1Ca0.1Co0.8Fe0.2O2.9 (LSCCF-112) and La0.7Sr0.2Ca0.1Co0.7Fe0.3O2.85 (LSCCF-213) were synthesized by conventional solid state reaction (CSSR). The forming process, microstructure and crystal structure of the prepared samples were analyzed by TG/DTA, SEM and XRD. The mixed conductivities of the samples were measured using DC four-terminal method in 150-950 °C. Thermal expansion coefficients (TEC) of the samples were tested in 20-950°C. LSCCF-112 and LSCCF-213 exhibit pure perovskite phase and porous structure after sintered at 1200 °C. The average TECs of LSCCF-112 and LSCCF-213 are 18.17×10-6 K-1 and 17.52×10-6 K-1 respectively. The mixed conductivity of the samples shows semiconducting behavior up to 700-750°C and then decreases as the temperature is further raised. At intermediate temperature (IT), the conductivity values of the samples are both much higher than 100 S/cm.


2013 ◽  
Vol 771 ◽  
pp. 59-62
Author(s):  
Jie Zhao ◽  
Jiang Fu ◽  
Yong Fu ◽  
Yu Na Zhao ◽  
Yong Chang Ma

Sr, Ca and Fe doped cathode materials Ln0.7Sr0.2Ca0.1Co0.7Fe0.3O2.85 (LnSCCF, Ln=La, Pr and Nd; abbreviated as L-72173, P-72173 and N-72173) were synthesized by microwave sintering (MWS) techniques. The formation process, phase structure and composition were characterized using TG/DTA, XRD and EDS. The thermal expansion behavior of the samples was analyzed in the range of 20-950 °C by thermal dilatometer. The electrical conductivity of the samples was measured with DC four-terminal method from 25 to 900 °C. The X-ray diffraction shows that the samples exhibit a single phase with rhombohedral or cubic perovskite structure after sintered at 1200 °C for 20 min. The electrical conductivity of the samples increases with temperature up to a maximum, and then decreases gradually at higher temperature owing to the creation of oxygen vacancies. The small polaron hopping is regarded as the conducting mechanism (T 550 °C). L-72173 has higher mixed conductivity ( >300 S·cm-1) in 550-800 °C. The average TECs of L-72173, P-72173 and N-72173 are 1.389× 10-5 K-1, 1.417 × 10-5 K-1 and 1.416 × 10-5 K-1 in the range of 25-800 °C, respectively. They are thermally matched to the GDC better than the YSZ and SDC.


2001 ◽  
Vol 21 (10-11) ◽  
pp. 1831-1835 ◽  
Author(s):  
D.P. Fagg ◽  
V.V. Kharton ◽  
A.V. Kovalevsky ◽  
A.P. Viskup ◽  
E.N. Naumovich ◽  
...  

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