Gd³⁺-doped lead molybdato-tungstates with the chemical formula of Pb_1−3x□_xGd_2x(MoO₄)_1−3x(WO₄)_3x (where x = 0.0455, 0.0839, 0.1430, corresponding to 9.53, 18.32, 33.37 mol% of Gd³⁺, respectively, as well as □ denotes cationic vacancies) were successfully synthesized via combustion route. The XRD and SEM results confirmed the formation of single-phase, tetragonal scheelite-type materials (space group I4₁/a) with the uniform, spherical and oval grains ranging from 5 to 20 µm. Individual grains are strongly agglomerated into big clusters with the size even above 50 µm. The magnetic measurements as well as the Brillouin fitting procedure showed paramagnetic state with characteristic superparamagnetic-like behaviour and the short-range ferromagnetic interactions. The electrical and broadband dielectric spectroscopy studies revealed insulating properties with the residual electrical n-type conduction of 2×10⁻⁹ S/m and low energy loss (tanδ ≈ 0.01) below 300 K. Dielectric analysis showed that no dipole relaxation processes in the Gd³⁺-doped materials were observed. A fit of dielectric loss spectra of Gd³⁺-doped samples by sum of the conductivity and the Havriliak-Negami, Cole-Cole, and Cole-Davidson functions confirmed this effect.

中文翻译：

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掺Gd 3+的钨钼酸铅的燃烧合成，结构，磁性和介电性能

化学式为Pb _{1−3 x} □ _x Gd _{2 x}（MoO ₄）_{1-3 x}（WO ₄）_{3 x的}Gd ³⁺掺杂的钨钼酸铅（其中x = 0.0455、0.0839、0.1430，对应于通过燃烧途径成功合成了9.53、18.32、33.37mol％的Gd ³⁺，并且□表示阳离子空位。XRD和SEM结果证实了单相四方白钨矿型材料的形成（空间群I 4 ₁ / a），均匀，球形和椭圆形的晶粒范围为5至20 µm。单个晶粒强烈团聚成大簇，大小甚至超过50 µm。磁测量以及布里渊拟合过程显示出顺磁性状态，具有特征性的超顺磁性行为和短距离铁磁相互作用。电气和宽带介电谱的研究显示绝缘特性与残余电Ñ的型传导2×10 ^-9 S / m和低能量损耗（tanδ δ低于300项K.介电分析≈0.01）表明，没有偶极弛豫过程中观察到掺有Gd ^3+的材料。Gd ³⁺的介电损耗谱拟合通过电导率和Havriliak-Negami，Cole-Cole和Cole-Davidson函数的总和掺杂的样品证实了这种效果。