A far ultraviolet spectroscopic study of the reflectance, luminescence and electronic properties of SrMgF4 single crystals

Structures and optical properties of two phases of SrMgF4

“…7a, the lowenergy PL in the 2-3.5 eV range (bands at 2.45, 2.67 and 2.0 eV) can be excited effectively by the 3.8 eV light from the SMF transparency range as well as in the 6.0 eV band. 9 The main part of these emissions is also excited by the X-rays: in this case hot charge carriers thermalize with further EE transfer both to excitons and point defects (see (4) in Fig. 7a).…”

“…Its red-shift in comparison with E g = 12.50 eV (ref. 9) is a result of strong excitonic absorption. The electronic structures, refractive indices, nonlinear susceptibility and polarizability were calculated by first-principles theory for both LT and HT phases.…”

“…7 Recent polarization-optical observations and preliminary X-ray structural studies in the 90-1200 K range for the SrMgF 4 crystal revealed a non-intrinsic ferroelastic phase transition with P112 1 (Z = 12) 2 Cmc2 1 (Z = 4), 8 and both phases remain pyroelectric, in contrast to the results by Abrahams. 7 In addition, the SMF reflection and photoluminescence were studied in detail using the synchrotron radiation 9 and its energy band gap was estimated to be E g = 12.50 eV. To date there are no experimental data concerning the fundamental absorption edge of SrMgF 4 , as well as its electronic structure and nonlinear susceptibility.…”

Crystal growth and electronic structure of low-temperature phase SrMgF4

“…One of the most interesting crystal family includes fluorides with general composition AMF 4 (A ¼Ba, Sr, Eu 2 þ or Sm 2 þ ); (M¼ Mg, Mn, Fe, Co, Ni, Cu, Zn) [22,23]. As to a strontium-carrying compound from this family, the SrMgF 4 crystal was extensively studied and the chemical, structural and spectroscopic properties of pure crystals were considered to reveal essentially the potentials of this noncentrosymmetric material for the use in optical applications [23][24][25][26][27][28][29]. Two polymorph modifications were found for SrMgF 4 and the layered structure of the low-temperature (LT) monoclinic phase, crystallized in space group P2 1 , is shown in Fig.…”

“…The structure is formed by complex layers of distorted (MgF 6 ) 4 À octahedrons. In parallel, the electronic structure of LT phase SrMgF 4 was evaluated by spectroscopic and theoretical methods, and a bandgap E g , as large as ∼12.5 eV, was determined [28,29,31]. The present study is aimed at the evaluation of the electronic structure of LT phase SrMgF 4 by X-ray photoelectron spectroscopy (XPS) for the first time.…”