On the existence of a new phase in SASD

Neutron irradiation induced paramagnetic centers are investigated using EPR. It is shown that the observed EPR signal appears to be mainly due to a variety of radicals. Temperature dependence of the EPR linewidth is attempted to be correlated both with the results supplied by inelastic neutron scattering spectra and by the recently developed theoretical model for phase transitions in sodium ammonium sulphate dihydrate type crystals.Парамагнітні центри, індуковані завдяки опроміненню нейтронами кристалу SASD, досліджуються методом ЕПР. Доведено, що спостережуваний ЕПР-сигнал походить від різноманітного типу радикалів SO−n . Встановлено кореляцію між температурнозалежною шириною лінії цього сигналу і спектром непружного розсіяння нейтронів, а також із нещодавно запропонованою теоретичною моделлю фазових переходів y сполуках типу амонієво-натрієвого дигідрату сірки

Measurements, Models, Systems and Design

531 s.

Spin-Phonon Interactions for PbF2\text{}_{2}:Gd3+\text{}^{3+} - Comparison between Theory and Experiment

The results implying from two microscopic models for spin-phonon interactions are analyzed for the case of PbF$\text{}_{2}$:Gd$\text{}^{3+}$ It is shown that the two-phonon first-order mechanism predicts significant contributions to the values of the spin-phonon second-order coupling constants and the one-phonon second-order mechanism is less effective

SPIN PHONON CONTRIBUTIONS TO THE B(2)(0) PARAMETER FOR GD3+ IN RBCDF3 SINGLE-CRYSTALS

Temperature dependence of the b2(0) spin-hamiltonian parameter for Gd3+ in RbCdF3 single crystals is described. The dependence is interpreted in terms of the 4f7 electrons coupling to the whole phonon spectrum of the crystal. The presented data give also an insight into the dynamics of charge compensators causing a tetragonal distortion of the crystal field

Dynamic Orbit-Lattice Interactions for PbF2\text{}_{2}:Gd3+\text{}^{3+} Single Crystals

Temperature dependence of the second-order spin-lattice coefficients for PbF$\text{}_{2}$:Gd$\text{}^{3+}$ is reported. It is shown that the thermal expansion of the crystal lattice contributes only in about 14 % to the observed dependence and the rest should be ascribed to a dynamic coupling between the 4f$\text{}^{7}$ electrons and lattice vibrations. The results are parametrized in both the Einstein and the Debye models and it is shown that the phenomenological parameters obtained from such parametrization can be made to coincide in both models if a specific value of the Einstein frequency ω$\text{}_{E}$ is properly chosen. Both models of parametrization show that the Γ$\text{}_{3_{g}}$ vibrating mode couples to the 4f$\text{}^{7}$ electrons much weaker than the Γ$\text{}_{5_{g}}$ one

DYNAMIC ORBIT-LATTICE INTERACTIONS FOR PBF2-GD3+ SINGLE-CRYSTALS

Temperature dependence of the second-order spin-lattice coefficients for PbF2:Gd3+ is reported. It is shown that the thermal expansion of the crystal lattice contributes only in about 14% to the observed dependence and the rest should be ascribed to a dynamic coupling between the 4f7 electrons and lattice vibrations. The results are parametrized in both the Einstein and the Debye models and it is shown that the phenomenological parameters obtained from such parametrization can be made to coincide in both models if a specific value of the Einstein frequency omega-E is properly chosen. Both models of parameterization show that the GAMMA-3g vibrating mode couples to the 4f7 electrons much weaker than the GAMMA-5g one

Spin-Phonon Contributions to the b20\text{}_{2}^{0} Parameter for Gd3+\text{}^{3+} in RbCdF3\text{}_{3} Single Crystals

Temperature dependence of the b$\text{}_{2}^{0}$ spin-hamiltonian parameter for Gd$\text{}^{3+}$ in RbCdF$\text{}_{3}$ single crystals is described. The dependence is interpreted in terms of the 4f$\text{}^{7}$ electrons coupling to the whole phonon spectrum of the crystal. The presented data give also an insight into the dynamics of charge compensators causing a tetragonal distortion of the crystal field