EKSPERIMENT 

             Iron stone crushed into powders. The powder was washed with distilled water until clear and then dried in an oven at a temperature of 70 °C. The dried powder is was separated with a magnetic separator in other to obtain pure powder Fe₂O₃. 

            Then test the X-ray fluorescence (XRF) to determine the content of the quantitative elements contained in both the iron ore and which have not been extracted and test DTA-TGA to determine element mass which is reduced due to temperature increase. 

           After that iron powder synthesized by co-precipitation method, in which the iron powder which has been extracted Fe₂O₃ was dissolved in 60 ml HCl 37% M and stirred with a speed of 650 rpm at 70 °C during 30 minutes. Then FeCl3 solution is formed, later dripped gradually NaOH solution at temperatures 100 °C until precipitate is formed Fe(OH)3.

         After that precipitate was washed repeatedly with distilled water until pH 7. subsequently precipitated Fe (OH) 3 produced, then filtered, dried and calcined at a temperature of 700 ° C, 800 ° C, 860 ° C, 900 ° C with holding time each sample was 5 hours. The results were characterized with UV-Vis spectrometer to determine absorbances.

The influence of calcination temperature on the optical properties of hematite (α-Fe₂O₃)

Abstract- The influence of calcination temperature on the optical properties of antiferromagnetic materials has been researched. Hematite (α-Fe₂O₃) is antiferromagnetic material with a rhombohedral lattice shape which has stable properties due to the influence of heat. The methods used are co-precipitation, which produces precursors in the form of FeCl3. Test results with X-ray fluorescence (XRF) showed that the biggest mineral content is with percentage of 98.02% Fe2O3 and test results with DTA-TGA showed occurrence of depreciation 1.8 mg mass at a temperature of 280 °C and 2.7 mg at a temperature of 860 °C, while testing by UV-Vis spectrometer was obtained absorbance of each is 1.573 a.u. at a temperature of 700 °C, 1.308 a.u at a temperature of 800 °C, 1.225 a.u at a temperature of 860 °C and 0.847 a.u at a temperature of 900 °C which can be regarded as a semiconductor material with a large energy gap of each that is 1.862eV, 1.948eV, 2.044eV and 2.243eV.

Keywords— Hematite, X-Ray Fluorescence (XRF), Co-precipitation, Calcination, Energy Gap, UV-Vis Spectrometer.