b RE1 xBixB3O6 (RE Sm, Eu, Gd, Tb, Dy, Ho, Er, Y) Bi(3+ Substitution Induced Formation of Metastable Rare Earth Borates at Ambient Pressure.
There emerge great interests in the syntheses of metastable polyborates; however, most are involved with the high pressure technique. A facile method to synthesize metastable rare earth borates at ambient pressure is eagerly required for the large scale production and property investigation. Here we demonstrate the critical role of Bi(3+ substitutions in the stabilization of metastable b REB3O6 (RE Sm, Eu, Gd, Tb, Dy, Ho, Er, and Y) at ambient pressure, where the Bi(3+ to RE(3+ substitutions would efficiently reduce the synthetic temperatures to 735 820 degC, well below the upper limit of thermodynamically stable window (840 980 degC) Partial solid solutions of b RE1 xBixB3O6 were prepared, and the ranges of the solution were also studied experimentally. The thermal behaviors of b RE0.8Bi0.2B3O6 were investigated by differential thermal analyses and powder X ray diffraction, and they were divided into two categories; that is, b RE0.8Bi0.2B3O6 (RE Sm, Eu, Gd) transfers to a RE0.8Bi0.2B3O6 with further increasing the temperature to 950 degC, while b RE0.8Bi0.2B3O6 (RE Tb, Dy, Ho, Er, and Y) decomposes into hexagonal REBO3 and B2O3. In particular, the allowed concentration of Bi(3+ in b Gd1 xBixB3O6 was 0.10 x 0.25, and these samples show bright blue emissions under UV excitation, which suggests the high efficiency of light absorption and high potential as phosphors with further doping of other activators.
Inorganic chemistry