The Stability and Ionic Conductivity in Cr Doped Y₂Ti₂O₇ in the Search for Potential SOFC Electrolyte Materials

Abstract

In this study, a series of Y2Ti2-xCrxO7 were synthesized by sol-gel method and characterized by powder X-ray diffraction (PXRD), scanning electron microscope energy dispersive spectroscopy (SEM-EDS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), temperature-programmed reduction (TPR), and AC-impedance to investigate their properties for the application of intermediate temperature solid oxide fuel cell (IT-SOFC). Y2Ti2-xCrxO7 existed single-phase in a range of 0 < x ≤ 0.8. The refined cell parameters decreased as the amount of doped Cr concentration increased. In addition, the TPR profiles showed that the as-prepared materials started to react with hydrogen in the temperature range of 350 - 450 ºC. The analyzed results of XPS suggested that the average oxidation state of Cr decreased with the increased Cr content. Measurements of ionic conductivities induced that the optimized performance was observed at x = 0.2 with 0.01 S/cm at 700 ºC due to an optimized condition of carrier concentration and carrier mobility. The ionic conductivity dropped under reducing condition, indicative of a p-type semiconductor. The as-prepared Y2Ti1.8Cr0.2O7 exhibits low electrical conductivity (0.0004 S/cm at 700 ºC) and good ionic conductivity, which is potentially suitable to be utilized as an electrolyte material for IT-SOFC.

The investigation of the photoluminescent and piezoelectric effect of Eu3+ doped Y2Ti2O7 and Sm2Ti2O7 host crystals

“…Y 2 Ti 2 O 7 is typical A 2 B 2 O 7 type pyrochlore compounds with cubic structure [15] and exhibits high melting temperature, high chemical and physical stability. Recently, Y 2 Ti 2 O 7 has been shown to have potential applications in many fields, such as candidate materials for actinides immobilization [16,17], photocatalysis for splitting water into H 2 and O 2 [18,19], dielectric materials [20,21] fluorescent materials [22][23][24][25] and solid fuel cells [26,27]. Especially, pyrochlore Y 2 Ti 2 O 7 is one of the interesting dielectric ceramics and it is dielectric constant (ε r ) is 54 [28].…”