ESR and NMR Study of Mixed Yttrium–Lutetium–Aluminum Garnets

Abstract

ESR of Mo3+ ions and NMR of 27Al nuclei is investigated in mixed single crystals of yttrium-lutetium-aluminum garnets (Y1-zL~z)3A15012, where 0 5 xs 1. Several new centres of Mo3+ and 27Al compared with Y,Al,O,, and Lu3A150,, single crystals are revealed associated with symmetry and crystalline field parameter changes a t isomorphous substitution of Y3+ ions in therare-earth sublattice of the garnet by those of Lu3+. Symmetry, nearest coordination, and parameters of spin-Hamiltonians are estimated concerning all of M03+ and 27Al centres in (Y1-zLu,),Al,O1, at6~a p y x c e~ pf€n HOBblX, no CpaBHeHtiIo C Y3AI,01, II Lu3A1501,, UeHTPOB M03+ ti 27A1, 06yCJIOBJEHHbIX ti3MeHeHHFIMH CtiMMeTpMti ti IlapaMeTpOB HPtiCTaJIJIHYeCKOrO nOJIII npH ti3OMOp@HO~ 3aMeHe Y3+ Ha LU3+ B penK03eMenbHOi nOAPC!lueTK€! rpaHaTOB. YCTaHOBJleHbI CEIMMeTPHH, 6ntimafiluee OKpyWeHEie EI OIIpeHeJleHbl IIapaMeTpbI CnHH-FaMHJlbTOHIIaHOB BCeX UeHTPOB Mo3+ ti 27Al B KpacTannax (Y1-zLuJ3A1501, npti x < 0,15.

Anomalous discrete disorder response of high-symmetry impurity centers spectra in garnet solid solutions

“…4, see also ref. 14. It follows from the C 3i symmetry (including trigonal axis and inversion) that all six Lu/Y positions are equivalent in relation to Cr 3+ (Al 3+ ).…”

“…The relative spectral contributions of different Cr 3+ centers in solid solution garnets are obviously determined by the statistics of the Lu/Y distribution. 3,14 The possibility of correlations in the Lu/Y distribution and the existence of ''preferred'' types of Cr 3+ (mLunY) centers cannot be excluded too. The weaker lines that may be seen in Fig.…”