Superlattice structure of Ce³⁺-doped BaMgF₄fluoride crystals - x-ray diffraction, electron spin-resonance, and optical investigations

Abstract

The x-ray diffraction patterns for Ce 3+ -doped BaMgF 4 (BMF) crystals suggest the existence of superlattice structure. The superlattice model is consistent with the characterization of the 4f 1 ground state of Ce 3+ as a probe ion using the electron spin-resonance (ESR) technique. The distinct Ce 3+ luminescence spectra with different peak energies and lifetimes also support the superlattice model. Although the detailed superlattice structure could not be analysed using the diffraction spots, a model has been proposed, taking into account the eight Ce 3+ polyhedra with different anion coordinations in the unit cell of the BMF crystal obtained from the ESR experiments.

Optical spectroscopy of Yb3+ centers in BaMgF4 ferroelectric crystal

“…16,20 Assuming this lattice site for Yb 3þ ions, the low C s symmetry of this cationic position will split the 2 F 7/2 and 2 F 5/2 states of Yb 3þ ions into 4 and 3 Kramer's doublets, respectively. They will be labeled as …”

“…Ferroelectric domain engineering has been reported in this material and the first demonstration of second harmonic generation by quasi-phase matching (QPM) with a ferroelectric fluoride has been shown in this system, 13 being the shortest converted wavelength obtained in the UV at 368 nm. 14 Moreover, doping this fluoride with trivalent rare Earth ions (RE), such as Nd 3þ , Ce 3þ , or Pr 3þ , has already been successfully achieved [15][16][17] showing the potential of BMF ferroelectric crystals as a nonlinear medium for all solid state lasers in the vacuum-UV/UV mid-infrared wavelength regions.…”

Local environment of optically active Nd3+ions in the ultratransparent BaMgF4ferroelectric crystal

“…11 At this point, it is important to mention that previous studies have pointed out that trivalent lanthanide ions substitute for Ba 2+ cations in the BMF crystal lattice. 19 This can be justified on the basis of the well-established set of ionic radii published by Shannon. 22 For the specific case of trivalent neodymium in coordination Figure 5 shows the angular variations of the g 2 factor in the three crystallographic (ab), (bc), and (ac) planes.…”

“…This can be explained with slightly magnetically nonequivalent sites related by a symmetry plane parallel to the (ac) plane, in agreement with the crystal structure. 19 The angular variations of the two lines in the (bc) plane are given on Fig. 5.…”

“…[19][20][21] In particular, the possibility of incorporating Nd 3+ ions has been recently demonstrated, opening the way to the development of potential self-frequency converted all solid-state lasers operating in the UV and vacuum-UV (VUV) and mid-IR spectral regions. 11 Namely, by means of site selective spectroscopy, it has been recently shown that Nd incorporates into the BMF matrix at two well-differentiated centers referred to as A (dominant) and B (minor) centers.…”