Nonlinear impedance as a function of A.C. voltage for glass 40Bi2VO5.5-60SrB4O7 annealed at 473 K for 3h and next fully crystallized measured with impedance spectroscopy method at high temperature region

The nonlinear electrcial properties as a function of A.C. voltage for annealed at 473 K for 3h and next fully crystallized 40Bi2VO5.5-60SrB4O7 glass was measured by impedance spectroscopy method. In order to prepare glasses two compounds: Bi2VO5.5 and SrB4O7 were synthesized via a solid state reaction route. The Bi2VO5.5 was synthesized from the stoichiometric mixture of initial powders of Bi2O3 and V2O5 which were ball-milled in pure acetone for 6 h at room temperature. The milling was performed in steps of 1 h with rest intervals of 10min. The mixture was heated up to 1020K in air and kept at this temperature for 24 h. The heating and cooling rate was of 50K h-1. The obtained powder was checked by X-ray diffraction method. The SrB4O7 was synthesized from the stoichiometric mixture of analytical grade SrCO3 and H3BO3 which were mashed in a mortar. Next the mixture was heated up to 1073K and kept at this temperature for 12 h. Samples of a composition of 40Bi2VO5.5–60SrB4O7 (in mol%) were prepared by the conventional melt quenching technique. The melting was conducted in alumina crucibles at 1373K for few min. The melts were poured onto a preheated (573 K) brass plate and pressed by another plate to obtain flat circular disks of 1–2mm thickness and 20–30mm diameter. Glass was annealed at 473 K for 3h and next heat treated up to 813 K to obtain glass-ceramic. For the electrical measurements gold electrodes were evaporated at the preheated samples. Impedance measurements were carried out in the temperature range from 573 K to 813 K, with the ac voltage varied from 0.1 to 3 Vrms with Concept 40 broadband dielectric spectrometer. The higher harmonic components (harmonic 0, harmonic 1 and harmonic 2) were measured for frequencies 0.1 and 1 Hz. Measurements were conducted during heating and cooling. Here the impedance for harmonic components was defined as the ratio of the voltage base wave to the n-th harmonic current component: Zn∗= U0∗/In∗, where Zn⁎ including the base wave generally depend on the sample voltage U1⁎ base wave amplitude. From Zn⁎ allother independent variables are calculated. The dependence of current density on the cosinusoidal electric field E(t)= E0cos(ωt) leads to the following expression: j´ = σ´0hE0 cos (ωt) + σ´1hE0 cos (2ωt) + σ´2hE0 cos (3ωt) + …Where σ´0h denotes base conductivity, while σ´1h, σ´2h etc. are higher harmonics conductivity. The admittivity for harmonic components with n ≥1, is calculated from relation σ⁎n = i2πfε0ε⁎n.

本数据集针对经473 K退火3小时后完全晶化的40Bi₂VO₅.₅-60SrB₄O₇玻璃，采用阻抗光谱法（impedance spectroscopy）测量其非线性电学性能随交流电压的变化关系。
为制备该玻璃样品，首先通过固相反应法（solid state reaction）合成两种前驱体化合物：Bi₂VO₅.₅与SrB₄O₇。其中Bi₂VO₅.₅以化学计量比的Bi₂O₃与V₂O₅初始粉末为原料，在纯丙酮中于室温下球磨6小时，球磨过程采用1小时研磨、10分钟间歇的分段模式；随后将混合粉末置于空气气氛中升温至1020 K并保温24小时，升降温速率均为50 K·h⁻¹；所得粉末通过X射线衍射（X-ray diffraction）进行物相表征。
SrB₄O₇则以分析纯SrCO₃与H₃BO₃为原料，在研钵中研磨混匀后，升温至1073 K并保温12小时。
采用常规熔体淬冷技术（melt quenching technique）制备成分为40Bi₂VO₅.₅-60SrB₄O₇（摩尔百分比）的样品：将原料置于氧化铝坩埚中，于1373 K下熔融数分钟；随后将熔体浇铸至预热至573 K的黄铜板上，并用另一块铜板压制成厚度1~2 mm、直径20~30 mm的扁平圆形圆盘。
将所得玻璃样品于473 K退火3小时，随后升温至813 K进行热处理以获得玻璃陶瓷。
电学测量前，在预热后的样品表面蒸镀金电极。采用Concept 40宽带介电谱仪（broadband dielectric spectrometer）进行阻抗测量，测试温度范围为573 K至813 K，交流电压幅值范围为0.1至3 Vrms。针对0.1 Hz与1 Hz两个频率，测量了0次谐波、1次谐波与2次谐波分量。测试过程涵盖升温和降温两个阶段。
谐波分量的阻抗定义为基波电压与n次谐波电流分量的比值：Zₙ* = U₀*/Iₙ*，其中包含基波在内的Zₙ*通常取决于基波电压U₁*的幅值。基于Zₙ*可计算得到所有其他独立变量。
当电场为余弦形式E(t) = E₀cos(ωt)时，电流密度的表达式为：j′ = σ′₀ₕE₀cos(ωt) + σ′₁ₕE₀cos(2ωt) + σ′₂ₕE₀cos(3ωt) + …其中σ′₀ₕ为基波电导率，σ′₁ₕ、σ′₂ₕ等为高次谐波电导率。
对于n≥1的谐波分量，其导纳率可通过关系式σₙ* = i2πfε₀εₙ*计算得到。