Preparation And Performance Study Of Perovskite-type Barium Zirconate/barium Zirconate Cerate Substrate Conductor

Acceptor-doped BaZrO₃,BaCeO₃ or Ba?ZrCe?O₃-based solid electrolyte is a proton conductor with a perovskite structure,and they are also outstanding candidates for the electrolyte separator in solid oxide fuel cells.The BaZrO₃-based proton conductor have poor sintering performance and low ionic conductivity.The BaCeO₃-based proton conductor have poor chemical stability and sintering properties.In this paper,the properties of BaZrO₃ and BaCeO₃ proton conductor were modified by adding the second phase?ZrO₂?_0.92?Y₂O₃?_0.08?YSZ?,sintering aid?ZnO?and sodium salt?NaCl/Na₂CO₃?to obtain ceramics with excellent performance.Firstly,BaZr_0.8Y_0.2O_3-?/YSZ?BZY/YSZ?composite ceramics were prepared by mechanical ball milling combined with high temperature sintering in air atmosphere.YSZ was added to improve the sintering performance and electrical conductivity of BZY.BZY-YSZ composite ceramics were investigated,and XRD results show that the composite electrolytes only consist of BZY and YSZ phases and there are no precipitates in BZY/YSZ grain boundaries according to the HR-TEM analysis.YSZ addition can improve the sintering properties of BZY-YSZ composite electrolytes.When the composite ceramics with YSZ content of 50 wt%are sintered at 1450^�C for6 h,the relative density and linear shrinkage are optimal,i.e.,98.17%and 17.26%,respectively,and the grains size is about 1.5?m.In dry air and moist air at 700^�C,the electrical conductivities of BZY-50%YSZ composite ceramics are 1.95�10^-44 S/cm and1.67�10^-44 S/cm,respectively.Secondly,the sintering properties and electrical conductivity of BZY are also improved by adding sintering aid?ZnO?and sodium salt?NaCl/Na₂CO₃?.BZY-ZnO-NaCl/Na₂CO₃ ceramics were prepared by the same method.When BZY ceramics with ZnO content of 2 mol%are sintered at 1450^�C for 6 h,the relative density and linear shrinkage are 95.25%and 16.76%,respectively,and the grains size is about 0.8?m¹?m.When BZY-2%ZnO ceramics with NaCl and Na₂CO₃ content of 5 mol%are sintered at 1400^�C for 4 h,the relative density of BZY-2%ZnO-5%NaCl and BZY-2%ZnO-5%Na₂CO₃ are 96.71%and 97.47%,and linear shrinkage are 17.89%and19.78%,respectively.In moist air at 700^�C,the electrical conductivity of BZY-2%ZnO-10%Na₂CO₃ ceramic is optimal,i.e.,3.124�10^-3 S/cm,while that of BZY-2%ZnO ceramic is 1.292�10^-3 S/cm.NaCl and Na₂CO₃ addition can raise the sintering performance and electrical conductivity of BZY-2%ZnO ceramic.In addition,Y and Sc co-doped BaZr_0.1Ce_0.7Y_0.2-xSc_xO_3-?ceramics were prepared by the same method.XRD analysis shows that BaZr_0.1Ce_0.7Y_0.2-xSc_xO_3-?is a single phase.When BaZr_0.1Ce_0.7Y_0.2O_3-?ceramics are sintered at 1450^�C for 6 h,the relative density and linear shrinkage are optimal,i.e.,94.89%and 12.56%,respectively,and the grains size is about 1.5?m³?m.At 700^�C,the total electrical conductivities of BaZr_0.1Ce_0.7Y_0.2O_3-?and BaZr_0.1Ce_0.7Y_0.1Sc_0.1O_3-?are 1.34�10^-2 S/cm and 7.68�10^-3S/cm,respectively,and the activation energies are 0.64 eV and 0.50 eV.Finally,BaZr_0.1Ce_0.7Y_0.1Sc_0.1O_3-??BZCYSc?ceramic was selected to be studied.The effects of ZnO and Na₂CO₃ composite addition on the sintering properties and electrical conductivity of BZCYSc ceramics were investigated by adding sintering aid ZnO and inorganic salt Na₂CO₃.All the sintered samples show single BZCYSc phase.The sintering temperature can be lowered to 1300^�C when 2 mol%ZnO is added.The grains size of BZCYSc-ZnO ceramic with Na₂CO₃ content of 5 mol%is about 2.5?m⁵?m.Na₂CO₃/ZnO composite addition is beneficial to improve the electrical conductivity of BZCYSc-2%ZnO ceramic when the measurement temperature is below450^�C.At 300^�C,the total electrical conductivity of BZCYSc-2%ZnO-10%Na₂CO₃and BZCYSc are 6.83�10^-55 S/cm and 1.72�10^-55 S/cm,respectively,while that of BZCYSc-2%ZnO-10%Na₂CO₃ and BZCYSc are 4.12�10^-33 S/cm and 6.51�10^-33 S/cm.