Phase Diagram and Soft Modes Behavior TbFe3–xGax(BO3)4 Solid Solutions with Huntite Structure.

The Raman spectra of four crystals of TbFe3–xGax(BO3)4 solid solutions (x from 0 to 0.54) were studied in the temperature range from 8 to 350 K. The temperatures of structural phase transitions were determined. The observed spectral behavior is characteristic to condensation and restoration of soft modes. Soft modes are associated with a structural phase transition from the R32 phase to the P3121 phase. The Compositions-Temperature phase diagram was constructed. [ABSTRACT FROM AUTHOR]