EPR Linewidth Studies of Gd³⁺‐Doped Yb_xY_1–xCl₃ · 6 H₂O Single Crystals Yb³⁺ Spin‐Lattice Relaxation Times

Study of Temperature Variation of EPR Linewidth of Gd3+‐Doped LiYbxY1−xF4 Single Crystals. Estimation of Yb3+ Spin–Lattice Relaxation Times

“…2 a and b and Table 1, i.e., the change in the n values with change in temperature in the ranges 290 to 180 K, 180 to 50 K, and 50 to 4.2 K, can be explained to be due to simple relaxation processes or by processes, which are combined with those responsible for the jumps, being effective in these ranges. The jumps in the log-log AH,, versus T plots are not due to the changes in the effective spin of Yb3+ ions, contrary to that pointed out in [5] and [6]. For, the occupation of the excited crystal-field levels changes smoothly with temperature, as can be seen by calculating the relative populations using Boltzmann factors and the energies of the excited levels.…”

“…The required conditions are clearly satisfied for the present X-band experiment, as discussed in context with Gd3+-doped Yb,YI-,C1,. 6 H,O single crystals [6]. The final expression, to be used, is where h is Planck's constant, the primed quantities refer to the host ions (Yb3+), while the unprimed quantities designate the impurity ions (Gd3+) ; the effective spin of Yb3+ ion S' is 512 in the temperature range 180 to 290 K, and n' is the number of Yb3+ host ions per unit volume.…”