The present work examines the effect of sintering temperature on the phase formation and the conductivity of Na_0.54Bi_0.46Ti_0.99Mg_0.01O_3-δ. The formation of the secondary phase and the poor grain boundary conductivity are a few major concerns in this recently developed material. Polycrystalline bulk specimens are fabricated through conventional pressureless sintering at different temperatures of 930 °C, 950 °C, 1000 °C, and 1050 °C for 2 h. A single rhombohedral perovskite phase is detected in the XRD profiles collected on all the sintered samples. However, the SEM micrographs reveal the existence of impurity phase in all the tested samples with the amount increasing considerably with the increase in temperature. The local elemental analysis of the impurity phase suggests the presence of non-stoichiometric Na_2xTi_2-xMg_xO₄ compound. However, the chemical composition of this compound varies across different specimens. The samples sintered at 950 °C exhibit the maximum bulk and grain boundary conductivities of 13.3 mS.cm⁻¹ and 3.6 mS.cm⁻¹, respectively, at 600 °C. A lower magnitude of both the conductivities is observed on sintering the samples at higher temperatures. The activation energy for bulk ionic conduction also decreases from 0.67 eV to 0.48 eV with the sintering temperature supporting the conjecture that higher Mg²⁺ amount is dissolved in the perovskite phase present in the samples sintered at 950 °C. The higher total conductivity in the samples sintered at 950 °C is attributed to the formation of comparatively less amount of Mg-rich impurity phase. Even though 950 °C appears to be an optimum sintering temperature, the grain boundaries of the samples continue to be resistive. At 600 °C, the grain boundary conductivity is less than one-third of the bulk conductivity. As a result, grain boundaries contribute a significant portion of the total resistivity offered by the Na_0.54Bi_0.46Ti_0.99Mg_0.01O_3-δ samples.

本工作研究了烧结温度对Na _0.54 Bi _0.46 Ti _0.99 Mg _0.01 O3 _-δ的相形成和电导率的影响。在这种新近开发的材料中，第二相的形成和较差的晶界电导率是几个主要问题。通过常规的无压力烧结，在930°C，950°C，1000°C和1050°C的不同温度下进行2小时，可以制造多晶块状样品。在所有烧结样品上收集的XRD谱图中检测到单个菱形钙钛矿相。然而，SEM显微照片揭示了在所有测试样品中存在杂质相，其含量随着温度的升高而显着增加。杂质相的局部元素分析表明存在非化学计量的Na _{2 x} Ti _{2- x} Mg _x O ₄复合。但是，该化合物的化学组成在不同的样品中会有所不同。在950°C下烧结的样品在600°C下的最大体积和晶界电导率分别为13.3 mS.cm ^-1和3.6 mS.cm ^-1。在较高温度下烧结样品时，观察到两种电导率都较低。随着烧结温度支持更高的Mg ²⁺的推测，本体离子传导的活化能也从0.67 eV降低到0.48 eV。的量溶解在950°C烧结的样品中存在的钙钛矿相中。在950°C下烧结的样品中较高的总电导率归因于形成的富镁杂质相相对较少。即使950°C似乎是最佳的烧结温度，样品的晶界仍然是电阻性的。在600°C时，晶界电导率小于整体电导率的三分之一。结果，晶界占Na _0.54 Bi _0.46 Ti _0.99 Mg _0.01 O3 _-δ样品提供的总电阻率的很大一部分。