【摘要】 以Nb2O5和Ta2O5为前驱反应物,KOH为矿化剂,采用水热法和聚合物辅助水热法两种合成工艺制备了KTa0.25Nb0.75(KTN)纳米晶。通过X线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(FEM)等技术,对合成产物进行了系统的研究。实验结果表明,表面活性剂聚乙烯醇(PVA)的量和矿化剂KOH的摩尔浓度是影响KTN纳米晶微观结构和形貌的关键因素。采用单纯水热工艺制备的KTN粉体,当c(KOH)达6mol/L、反应温度为200℃及反应时间24h,可生成纯钙钛矿相KTN。在较高碱度条件(c(KOH)=8mol/L)下,表面活性剂PVA的量不改变水热反应最终产物,但晶粒尺寸随表面活性剂量的加大逐渐减小。在较低碱度条件(c(KOH)=4mol/L)下,加入适量的表面活性剂PVA有利于在较温和条件下生成纯钙钛矿结构KTN纳米晶。更多还原

【Abstract】 Nanocrystalline potassium tantalite niobate KTa0.25Nb0.75(KTN)nanocrystalline have been synthesized by hydrothermal method and additive-assisted hydrothermal synthesis by using Nb2O5and Ta2O5as precursors,KOH as mineralizer.The obtained particles were characterized by X-ray powder diffraction,scanning electron microscope(SEM),transmission electron microscope(FEM).The experimental results show that the microstructure and morphology of nanocrystal mainly depend on the amount of surface active agent polyvinyl alcohol(PVA) and the molar concentration of KOH.The most suitable condition for the formation of perovskite KTN is that the c(KOH)concentration is up to 6mol/L,reaction temperature is 200℃and reaction time is 24hby the single hydrothermal method.Using additive-assisted aqueous synthesis in higher pH values(c(KOH)=8mol/L)of solvents, the amount of PVA has no avail on the end product,but the size of nanocrystalline decreases along with increase of the surface active agents.While in lower pH values(c(KOH)=4mol/L)of solvents,adding moderate surface active agent PVA is in favor of synthetizing pure perovskite KTN nanostructure under relative mild condition.更多还原