Effect of Ca2+ site substitution on structural, optical, electrical and magnetic properties in Nd3+ and Mn2+-co-doped calcium molybdato-tungstates

Magnetic and Electrical Characteristics of Nd3+-Doped Lead Molybdato-Tungstate Single Crystals

“…However, its value significantly increases with increasing temperature, i.e., in the intrinsic region above 300 K for a sample richer in neodymium ions, regardless of the crystallographic direction. Similar behavior of S 2 σ(T) with only a few fW/(cmK 2 ) was observed in ceramic Gd 3+ and Co 2+ -co-doped calcium molybdato-tungstates [ 46 ] as well as in Nd 3+ and Mn 2+ -co-doped calcium molybdato-tungstates [ 47 ]. The above mentioned studies show that even in ion-bonded materials containing a constant content of 3 d transition metal ions, thermoelectric efficiency can be improved by doping them with 4 f rare-earth ions.…”

Magnetic and Electrical Characteristics of Nd3+ and Mn2+-Co-doped Calcium Molybdato-Tungstates Single Crystals

“…However, lead molybdato-tungstate single crystals doped with Nd 3+ ions exhibited n-type semiconducting properties in the intrinsic region and a Fermi energy of 0.04 eV (derived from the diffusion component of thermopower), characteristic of shallow donor levels. 24 Summarizing our results on a wide group of scheelite-type materials (micro-or nanopowders) codoped with divalent d-electron metal ions and trivalent rare-earth metal ones, it can be stated that paramagnetism is dominant everywhere, mainly due to the screening of electrons in the 4f subshells of RE 3+ ions. For the samples poorer in magnetic ions, magnetic contributions independent of temperature, such as orbital diamagnetism or Van Vleck paramagnetism in nonmetals, played an important role.…”

“…41 The χ 0 factor was determined from the linear function χT(T) in the Curie−Weiss region from the eq 7. 24 = + T b T 0 (7) where b is the intercept, and χ 0 is the slope. The dependencies of product χ ZFC •T(T) from the measurement and the asymptotes determined from eq 7 in the Curie−Weiss region are shown in Figure 3, and parameters b and χ 0 are shown in Table 1.…”

“…In a solid solution with the same chemical formula as the studied single crystals, synthesized by a hightemperature solid-state reaction with a content of 0.0050 ≤ x ≤ 0.2000 and y = 0.0200, 25 it was observed that for samples poorer in manganese, the μ eff is slightly larger than the p eff , and for samples richer in manganese, vice versa. On the other hand, in the single crystals of the Pb 1−3x □ x Nd 2x (MoO 4 ) 1−3x (WO 4 ) 3x solid solution (x = 0.0010 and 0.0050), 24 it was observed that the values of the effective magnetic moment (μ eff ) are much higher than the effective number of Bohr magnetons (p eff ). This difference was explained by the fact that some molybdenum ions may be in an oxidation state lower than +6, contributing to an increase in the net magnetic moment.…”

“…Similar behavior was observed for polycrystalline samples 25 of the same solid solution as the single crystals under study, as well as for single crystals of Pb 1−3x □ x Nd 2x (MoO 4 ) 1−3x (WO 4 ) 3x solid solution. 24 The reason for this could be a magneto-crystalline anisotropy.…”