ИСТИНА

Pulse methods of electron paramagnetic resonance are used to determine relaxation properties of paramagnetic centers formed by impurity ytterbium ions in synthetic forsterite (Mg2SiO4) single crystals. Yb3+ ions substitute Mg2+ ions both as single ions and as dimer associates with nearby magnesium vacancy. Measurements in temperature range 5 – 15 K showed that for all paramagnetic centers the time dependences of echo amplitudes are well described by a simple one-exponential decay. It was found that at temperatures T  10 K phase relaxation time of single Yb3+ ions in the M1 site is longer than that for Yb3+ ion in the M2 site, but it is shorter than that for the dimer associate of Yb3+ ions in the M1 sines. It is established that spin-lattice relaxation of Yb3+ ions in Mg2SiO4 is due to joint action of direct one-phonon process, Raman two-phonon process and resonance two-phonon Aminov-Orbach process.