Electronic structure of β-RbSm(MoO₄)₂and chemical bonding in molybdates

Abstract

Microcrystals of orthorhombic rubidium samarium molybdate, β-RbSm(MoO4)2, have been fabricated by solid state synthesis at T = 450 °C, 70 h, and at T = 600 °C, 150 h. The crystal structure has been refined by the Rietveld method in space group Pbcn with cell parameters a = 5.0984(2), b = 18.9742(6) and c = 8.0449(3) Å (R(B) = 1.72%). Thermal properties of β-RbSm(MoO4)2 were traced by DSC over the temperature range of T = 20-965 °C, and the earlier reported β ↔ α phase transition at T ∼ 860-910 °C was not verified. The electronic structure of β-RbSm(MoO4)2 was studied by employing theoretical calculations and X-ray photoelectron spectroscopy. It has been established that the O 2p-like states contribute mainly to the upper part of the valence band and occupy the valence band maximum, whereas the Mo 4d-like states contribute mainly to the lower part of the valence band. Chemical bonding effects have been analysed from the element core level binding energy data. In addition, it was found that the luminescence spectrum of β-RbSm(MoO4)2 is rather peculiar among the Sm(3+) containing materials. The optical refractive index dispersion in β-RbSm(MoO4)2 was also predicted by the first-principles calculations.

Exploration of structural, vibrational and spectroscopic properties of self-activated orthorhombic double molybdate RbEu(MoO4)2 with isolated MoO4 units

“…In this case, it is difficult to exhibit in detail the correlations between the photoluminescence parameters and crystallographic environment of Eu 3+ ions. To solve the problem, the europium compounds can be considered because, in this case, the Eu 3+ ion positions can be precisely determined by the methods of crystal structure analysis [13][14][15][16][17][18][19][20].…”

“…Available information on the existence and structural properties of molybdates with general composition RbLn(MoO4)2 is very limited [21]. Recently, RbNd(MoO4)2 and RbSm(MoO4)2 molybdates have been synthesized, their structures have been defined in space group Pbcn and electronic structures have been calculated [20][21][22][23][24][25]. The set of heavier Ln elements, where the formation of orthorhombic structure is possible, remains unclear because, to our best knowledge, only RbYb(MoO4)2 and RbLu(MoO4)2 were considered earlier and monoclinic, and trigonal symmetries, respectively, were reported for the compounds [26,27].…”

The Preparation and Optical Properties of Novel LiLa(MoO4)2:Sm3+,Eu3+ Red Phosphor

“…Figure 3 shows the relevant emission spectra under 403 nm excitation. The LL 1− x M: x Sm 3+ samples have three emission peaks at 562 nm ( 4 G 5/2 → 6 H 5/2 ), 598 nm ( 4 G 5/2 → 6 H 7/2 ) and 644 nm ( 4 G 5/2 → 6 H 9/2 ) [49,50]. The band at 598 nm corresponds to yellow-orange light and that at 644 nm to deep red, so LL 1− x M: x Sm 3+ samples emit red-orange light, having potential applications in the LCD back light and white LED.…”

Crystal growth and electronic structure of low-temperature phase SrMgF4

“…For this reason, it is difficult to use the absolute BE values of the constituent element core levels from different studies as the key parameters for a detailed evaluation of the chemical bonding effects, unless the calibration methods are the same. To overcome this problem, the BE difference was adopted as a suitable parameter for dielectrics because this parameter is insensitive to the charging-induced energy scale drift [56][57][58][59][60][61]. In the present case, BE differences ΔBE Sr ¼BE(F 1s)-BE (Sr 3d 5/2 ) and ΔBE Mg ¼ BE(F 1s)-BE (Mg 2p) are optimal and the parameters are depicted in Tables 2 and 3.…”