微波水热-固相法制备钙铁石型Ca_2Fe_2O_5粉体及其表征

以硝酸铁和硝酸钙为原料,草酸铵作为络合剂,用氨水调节pH,采用微波水热-固相法制备钙铁石型Ca2Fe2O5粉体.利用XRD和SEM对产物的物相和微观形貌进行表征,结果表明:微波水热预处理后得到的CaCO3-Fe2O3复合氧化物,颗粒度小,反应活性较高,在700℃下焙烧3h便可制备正交晶系的Ca2Fe2O5粉体.

高能球磨合成铁酸钙粉体的形貌及物相分析

以CaCO3、Fe2O3为原料,采用高能球磨结合热处理的工艺,制备了Ca2Fe2O5粉体。借助X射线衍射分析、扫描电子显微镜测试手段,分析了球磨时间与热处理条件等工艺因素对合成Ca2Fe2O5粉体物相及形貌的影响。同时根据球磨3 h原料差热曲线分析结果,得到了材料合成温度及温度范围与实验结果相符合,并探讨了高能球磨对产物合成的影响机理。结果表明:高能球磨能够降低铁酸钙粉体的合成温度,在球磨3 h,800℃热处理24 h的条件下,可以得到高纯度的Ca2Fe2O5粉体,同时球磨时间对热处理后粉体的颗粒形貌也有影响。

Temperature Dependence of the Magnetic and Electric Properties of Ca₂Fe₂O₅

Ca2Fe2O5 powder sample, were prepared to investigate the origin of the weak ferromagnetic component reported in literature for calcium ferrite single crystals. In this work, the calcination method was used to produce nanocrystalline powders of Ca2Fe2O5. XRD measurement has shown the presence of Fe3O4 magnetite and CaO as impurity phases. The ferrimagnetic phase deeply influences the magnetic behavior with features very similar to those reported in literature for Ca2Fe2O5, both powders and single crystals. Our results support the hypothesis that the weak ferromagnetic component observed in Ca2Fe2O5 can be also due to the presence of magnetite impurity traces in the samples. The powders were submitted to calcination processes at 500℃ for 2 hours and 950℃ for 16 hours. The sintered sample was submitted at 1050℃ for 6 hours and characterized by X-Ray Powder diffraction (XRD), dielectric measurements, Magnetization and Scanning Electron Microscopy (SEM) analysis.

微波协助溶胶-凝胶法制备Ca_2Fe_2O_5及其光催化性能

钙钛矿型复合氧化物Ca2Fe2O5是一种新型的窄带隙半导体光催化材料。以Fe（NO3）3×9H2O、Ca（NO3）2×4H2O、聚乙烯醇和尿素为主要原料,采用微波协助溶胶-凝胶法成功制备了Ca2Fe2O5。通过X射线衍射（XRD）、扫描电镜（SEM）、红外光谱（FT-IR）和漫反射谱（DRS）对Ca2Fe2O5进行了表征,并研究了煅烧温度对Ca2Fe2O5光催化性能的影响。结果表明:7001000℃煅烧都能得到Ca2Fe2O5;其中,800℃煅烧得到的Ca2Fe2O5光催化性能最佳,其粒径为80100nm,带隙吸收边波长为548nm,对应带隙宽度为2.3eV;在可见光条件下,800℃煅烧得到的纳米Ca2Fe2O5对模拟污水甲基橙表现出了优良的光催化降解性能。微波协助溶胶-凝胶法制备的Ca2Fe2O5光催化活性明显优于单一溶胶-凝胶法制备的Ca2Fe2O5,是一种在污水处理方面具有应用前景的可见光催化剂。