Manganese Luminescent Centers of Different Valence in Yttrium Aluminum Borate Crystals

We present an extensive study of the luminescence characteristics of Mn impurity ions in a YAl(3)(BO(3))(4):Mn crystal, in combination with X-ray fluorescence analysis and determination of the valence state of Mn by XANES (X-ray absorption near-edge structure) spectroscopy. The valences of manganese Mn(2+)(d(5)) and Mn(3+)(d(4)) were determined by the XANES and high-resolution optical spectroscopy methods shown to be complementary. We observe the R(1) and R(2) luminescence and absorption lines characteristic of the (2)E ↔ (4)A(2) transitions in d(3) ions (such as Mn(4+) and Cr(3+)) and show that they arise due to uncontrolled admixture of Cr(3+) ions. A broad luminescent band in the green part of the spectrum is attributed to transitions in Mn(2+). Narrow zero-phonon infrared luminescence lines near 1060 nm (9400 cm(−1)) and 760 nm (13,160 cm(−1)) are associated with spin-forbidden transitions in Mn(3+): (1)T(2) → (3)T(1) (between excited triplets) and (1)T(2) → (5)E (to the ground state). Spin-allowed (5)T(2) → (5)E Mn(3+) transitions show up as a broad band in the orange region of the spectrum. Using the data of optical spectroscopy and Tanabe–Sugano diagrams we estimated the crystal-field parameter Dq and Racah parameter B for Mn(3+) in YAB:Mn as Dq = 1785 cm(−1) and B = 800 cm(−1). Our work can serve as a basis for further study of YAB:Mn for the purposes of luminescent thermometry, as well as other applications.