Synthesis,Exfoliation And Property Of Layered Perovskite

Layered perovskite compounds can generally be regarded as alternate stacking of tetragonal or hexagonal perovskite layer with other structural matching layer.In these structures,not only site A or B can be substituted with adequate elements,but intercalation can also take place between constituent layers,which expands their application in giant magnetoresistance,photocatalysis,photoluminescence and gas sensors,etc.Three layered perovskite compounds were synthesized according to literatures,and their exfoliation,photoluminescence and humidity sensing property were also studied.Dion-Jacobson?D-J?phases with nominal composition of K(K_1.5Eu_0.5)Ta₃O₁₀ was prepared by using traditional solid state reaction.Optimum conditions for the exfoliation of constituent layers with microwave assistance were studied,and lamellar(K_1.5Eu_0.5)Ta₃O₁₀ can be obtained in a short time.Humidity sensitive test of K(K_1.5Eu_0.5)Ta₃O₁₀ was performed,results showed that the sensitivity curve exhibit good linear response.As the humidity alternate between 11% RH and 85% RH,the response and recovery time is about 6 s and 2 s respectively,showing fast response and recovery characteristics.The humidity sensing hysteresis is about 7% RH.The stability test performed within 60 days indicated that the sensor has very good long time stability.La₄Ba_2.6Ca_2.4Mn₄O₁₉ and La₂Ca₂MnO₇ were synthesized by citric acid complex method according to literatures.Results of doping in La₄Ba_2.6Ca_2.4Mn₄O₁₉ showed that: partial substitution on site B is difficult,but element substitution on site A is a little easier than site B.The only emission peak of La₄Ba_2.6Ca_2.4Mn₄O₁₉:x%Eu³⁺ is located at 617 nm.In the exfoliation to La₂Ca₂MnO₇,proton exchange can be observed in the weak acid environment.