Photoacoustic spectra of mixed ceramics of Al2O3 and Cr2O3

Qualitative investigation of Cr3+ ion concentration dependence of the optic al absorption characteristics in mixed ceramic Al2-xCrxO3 (0 less than or e qual tox less than or equal to2) measured by photoacoustic (PA) spectroscop y have been carried out. Two peaks which correspond to U- and Y-bands ((4)A (2) --> T-4(2) and (4)A(2) --> T-4(1) transitions, respectively) can be obs erved up to the mole fraction x of 2.0. The peak positions of U- and Y-band s shift to lower photon energy region with the increase of mole fraction x. However, the decreasing rate of the Y-band is more rapid than that of the U-band, indicating the difference of the formation of electronic structures between U-band and Y-band with the increase of mole fraction x. The widths of U- and Y-bands increase with the increase of mole fraction x. The incre ase of the Y-band is slightly larger than that of the U-band (similar to 0. 05 eV), indicating the difference between U-band and Y-band formation of th e influence of the increase of mole fraction x.