Electric relaxation of superparamagnetic Gd-doped lead molybdato-tungstates

Effect of Tantalum Substitution on Dielectric Constant of ZnSb2-xTaxO6 Solid Solution (x=0.0,0.1,0.25,0.75,1.6)

“…The estimated level of porosity p l from calculated d cal and measured d exp densities with an average value below one percent does not have a significant impact on the processes described above. A similar phenomenon was observed for Pb 1−3x x Gd 2x (MoO 4 ) 1−3x (WO 4 ) 3x materials (x = 0.0455, 0.0839, 0.1154, 0.1430, 0.1667, and 0.1774, where denotes vacancies) [8] and for RE 2 W 2 O 9 ceramics (RE = Pr, Sm-Gd) [9] that have a higher density. The accumulation of electric charge is also influenced by those ions that have unscreened electrons in unfilled shells.…”

Combustion synthesis, structural, magnetic and dielectric properties of Gd3+-doped lead molybdato-tungstates

“…In the reduced coordinate (H/T) the magnetic isotherms fall exactly on a universal Brillouin curve for all samples under study (Fig. 6(c) [33] obtained by high-temperature solid state reaction method. To investigate the nature of magnetism in the Gd 3+ -doped materials obtained by combustion route, the Brillouin fitting procedure was applied [47] Table 1 showed a slight deviation of the Landé factor from g = 1.98 for x = 0.0455 to g = 1.88 for x = 0.1430.…”

“…Individual grains were also agglomerated to form very big clusters. The morphology of these materials was described precisely in our previous paper [33].…”

“…Our studies on electrical and magnetic properties of new tungstates [21][22][23][24][25][26][27][28], molybdates [29][30][31], and molybdato-tungstates [28,32,33] doped with rare earth ions (RE 3+ ) and obtained both in the form of nano-, micropowders, and single crystals have shown that they are non-conductive paramagnetics or superparamagnetics. The reason for this is the strong electron screening on 4f-shells.…”

“…Recently, we carried out magnetic and broadband dielectric spectroscopy measurements on samples of Pb 1-3x x Gd 2x (MoO 4 ) 1-3x (WO 4 ) 3x solid solution (x = 0.0455, 0.0839, 0.1154, 0.1430, 0.1667, 0.1774) obtained by solid state reaction method [33]. The results showed a paramagnetic state with characteristic superparamagnetic-like behaviour and an existence of the faster (for Gd 3+ -poorer samples with x up to 0.1154) and slower (for Gd 3+ -richer samples with x  0.1154) relaxation processes [33]. The slowing down of relaxation process was explained by the increase of sample density with increasing Gd 3+ ion content.…”