Ruby (A1203 -Cr 3+) is a very fashionable optical material. It would be very interesting to investigate what happens when Eu 3+ ion, another excellent luminescent active ion, replaces the Cr 3+ ion in the A1203 matrix, because of its excellent luminescent property. However it is not simple to dope europium into the AI203 matrix by traditional solid phase reaction, because of the large difference of ion radii between Eu 3+ and either AI 3+ or C r 3+. S u c h a difference makes it very difficult for the Eu 3+ ion either to replace the A13+ or to maintain the vacancy of the A1203 lattice. A sol-gel technique has been successfully used to synthesize A1203 . Eu 3+, Bi 3+ in our laboratory. This material was then investigated using X-ray diffraction and Eu 3+ ion luminescence spectroscopy to determine its crystal structure, to examine its luminescent properties and to collect information about the site of Eu 3+ ion in the A1203 lattice.
AI(i-OC3HT)3, E u ( N O 3 ) 3 and Bi(NO3) 3 were used as reactants to synthesize Al(2_x)O 3 β’ 0.06Eu ?+, 0.004Bi 3+, where x = 0.064 (we will symbolize it as A1203 β’ Eu 3+, Bi 3+ later on in this report) via a sol-gel technique at a temperature of 950 Β°C, which is much lower than that of the traditional solid phase reaction. The optimum conditions for transitions from sol to gel and from gel to solid powder were obtained through numerous experiments. The synthesized powder was then heated to 1000 Β°C for 4 h in a furnace and cooled to room temperature in the same furnace by turning off the furnace power.
To examine what crystal structure the compound exhibits, we first performed an X-ray diffraction (XRD) study. A Rigaku 12 kW rotary anode X-ray diffractometer with CuK radiation was employed together with a graphite monochromator. The tube voltage was 50kV and the anode current was 150mA. The powder sample was examined with 20 varying from 20 Β° to 80 Β° . The diffraction lines obtained Were very diffuse. After careful examination and comparison of our data with those from listed possible crystal structures of A1203 among the ASTM cards, we found out that the lines could best be indexed based on 8-A1203. Table I lists the observed diffraction lines in our sample and some lines from 8-A1203 assigned by the ASTM card. Although we