Crystal-field excitations in PrAl₃and NdAl₃at ambient and elevated pressure

Abstract

The crystal fields (CFs) of the binary rare-earth compounds PrAl3 and NdAl3 have been examined at ambient pressure by means of inelastic neutron scattering. The CF of the latter compound has also been measured under hydrostatic pressure (p = 0.84 GPa). The observed substantial changes of the CF under pressure are discussed within the framework of first-principles density functional theory calculations.

Crystal field interactions in DyFe2Si2 and DyFe2Ge2

“…The explanation of such a large change in the CEF parameters cannot be explained by merely considering the changes in the lattice volumes. Rather effects like a suppressed screening due to conduction electrons leading to increased effective charges of the ligands and hence to an increased CEF must be considered [17], which have not been taken into account in the present work. The crystal field strength defined by relation (2) is reduced by 1.41 times and the overall separation of the lowest 6 H 15/2 state is also reduced by 1.62 times on substitution of Ge for Si in DyFe 2 Si 2 .…”

Pressure-Induced Switch of the Direction of the Unique Jahn−Teller Axis of the Chromium(II) Hexaqua Cation in the Deuterated Ammonium Chromium Tutton Salt

“…The instrumental settings were configured for maximum resolution at the elastic peak. Measurements under quasi-hydrostatic pressure were conducted using a clamp cell described previously . The sample was finely ground and packed into the cell stepwise, alternating with the addition of several drops of Fluorinert FC-77 (Fluka) acting as the pressure-transmitting medium.…”

Effects of High Pressure on the Luminescence Spectra of Eu(SO4)2·NH4 Microcrystals: Anisotropically Induced Structural Distortions

“…Focusing on the pressure effects that characterize the R 3+ optical spectra, − and because Eu 3+ is the obvious choice among all R 3+ , this work presents a systematic evaluation of a number of pressure-dependent characteristics of local Eu 3+ environments, i.e., the covalence, evolution of the spin−orbit interaction, and very especially the symmetry and distribution of the distances to the ligands in the stoichiometric Eu(SO 4 ) 2 ·NH 4 crystal, through the analysis of room-temperature photoluminescence spectra under different pressure conditions. The good resolution of the emission transitions, due to the ordered crystalline nature of Eu(SO 4 ) 2 ·NH 4 , along with the sequence of observed energy levels corresponding to 5 D 0 → 7 F J transitions up to J = 4, beyond the 7 F 2 usually studied for Eu 3+ glass materials, − ,, are advantages for achieving accurate results in the current parametrization of Eu 3+ crystal field interactions.…”