Effects of MoO_3 Amounts on Sintering and Electrical Properties of Ce_(0.8)Nd_(0.2)O_(1.9)

The high purity （Ce0.8Nd0.2O1.9）1-x（MoO3）x（x=0, 0.005, 0.010, 0.020; Ce0.8Nd0.2O1.9=NDC） solid solutions were prepared by modified sol-gel method. The structures and electric conductivities were characterized by X-ray diffraction（XRD）, field-emission scanning electron microscopy（FESEM） and electrochemical impedance spectros copy（EIS）. The XRD results show that the materials were pure phase with a cubic fluorite structure. Compared to the undoped-NDC samples, MoO3 doped-NDC showed higher sintered density（over 96%） at reduced sintering tempera ture. The electric conductivity（σt） of （Ce0.8Nd0.2O1.9）1-x（MoO3）x at 400 °C was 9.58×10-4 S/cm when x=0.010, which was higher than that of undoped-NDC samples（σt=3.29×10-4 S/cm）. The obtained optimal amount of the MoO3 was x=0.010 in this system.

Proton transport controlled at surface layer of CeO_(2) by gradient-doping with a built-in-field effect

Ceramic fuel cells hold an important position for the sustainable energy future using renewable energy sources with high efficiency.The design and synthesis of active materials,interface engineering and having capability of low operating temperature is considered as an important factor to further increase the power output and stability of ceramic fuel cell devices.A novel methodology has vital importance to develop new functionalities of existing materials by introducing new different effects.The built-in electric field(BIEF) is one of the most recently used approaches to improve charge transfer and ionic conductivity of solid oxide materials.Herein,we demonstrate gradient doping strategy in CeO_(2)-δstructure to produce BIEF effect and to modulate the proton transport effectively at the surface layer rather than bulk structure.The inclusions of La and Sr metal ions at the surface and Co-metal ions into bulk-layer of CeO_(2)form the gradiently doped structure.The gradient doping into CeO_(2)highly improves the proton transport properties through the surface layer by modifying the energy levels.Moreover,unbalanced charge distribution due to gradient doping produces built-in electric-field to provide extra driving force for protons transport through surface layer.The acquired gradiently doped fluorite structure exhibits remarkable proton conductivity of>0.2 S/cm,as a result ceramic fuel cell shows power output of>1000 mW/cm2while operating at 500℃.This unique work highlights the critical role of gradiently doped electrolyte in electrochemical conversion energy devices and offers new understanding and practices for sustainable energy future.

Study on rare earth electrolyte of SDC

The grain boundaries of polycrystalline oxygen ion conductors presented a blocking effect on the oxygen ionic transport across them. It was found that the apparent specific grain boundary conductivity was 2-3 orders of magnitude lower than the bulk conductivity in the temperature range of 200-500 °C for normal purity Ce0.85Sm0.15O1.925 (SDC) with an average grain size of 320-580 nm. The apparent specific grain boundary conductivity increased with decreasing average grain size. It was found that the space charge potential was nearly independent of grain size, and the reason was analyzed. The increase of the conduction path width was responsible for the increase in the apparent specific grain boundary conductivity.