A位掺杂Ru对SPS制备LaCrO 3 陶瓷导电性的影响及其作为熔盐中惰性阳极的可行性

Lanthanum chromate (LaCrO3) ceramic materials have extensive application values in fields such as high-temperature thermoelectricity and solid oxide fuel cells (SOFC). However, its disadvantages such as poor sintering performance and low electrical conductivity limit the high-performance application of LaCrO3 ceramics. In response to the above problems, a dense LaCrO3 bulk is prepared by spark plasma sintering (SPS). At the same time, by doping the A-site with Ru elements, it is expected to achieve a doped lanthanum chromate (La1−xRuxCrO3) dense ceramic with high electrical conductivity. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis results of the obtained samples show that regardless of the content of the A-site Ru element (x = 0 - 0.25, x is the atomic content of Ru), the samples obtained by SPS all have a single-phase perovskite structure and a relatively high density. In addition, the high-temperature electrical conductivity test results show that the electrical conductivity of the doped La1−xRuxCrO3 increases with the increase of temperature and the amount of Ru doping. At the same time, the conductivity of La1−xRuxCrO3 before and after doping both satisfy the Arrhenius formula, and the electrical conductivity activation energy of the doped La1−xRuxCrO3 ceramic is significantly lower than that of the undoped LaCrO3 ceramic. Subsequently, La1−xRuxCrO3 is placed in a molten CaCl2 melt at 800 °C to study its feasibility as an inert anode material for molten salt electrolysis. The results show that the doped La1−xRuxCrO3 has a relatively high resistance to molten salt chemical corrosion, but its thermal shock resistance is poor, and obvious mechanical peeling on the surface layer occurs after electrolysis. The above results indicate that the doped La1−xRuxCrO3 has the chemical stability as an inert oxygen evolution anode material, but its thermal stability needs to be further improved to be suitable for an inert anode for molten salt electrolysis.

铬酸镧（LaCrO3）陶瓷材料在高温热电和固体氧化物燃料电池（SOFC）等领域具有广泛的应用价值，然而其烧结性能差、导电率低等不足却限制了LaCrO3陶瓷的高性能应用。针对上述问题，采用放电等离子烧结（SPS）方式制备致密的LaCrO3块体。同时，通过A位掺杂Ru元素，以期实现高电导率的掺杂态铬酸镧（La1−xRuxCrO3）致密陶瓷。所得样品的X射线衍射（XRD）及扫描电子显微（SEM）分析结果表明，无论A位Ru元素含量多少（x=0～0.25， x为Ru的原子含量），SPS所得样品均为单相钙钛矿结构，且具有较高的致密度。此外，高温电导率测试结果显示，掺杂态La1−xRuxCrO3的电导率随着温度和Ru掺杂量的增加而增加。同时，掺杂前后La1−xRuxCrO3导电性均满足Arrhenius公式，且掺杂态La1−xRuxCrO3陶瓷的电导活化能明显低于未掺杂的LaCrO3陶瓷。随后，将La1−xRuxCrO3置于800 °C熔融CaCl2熔体中，研究其作为熔盐电解用惰性阳极材料的可行性。结果显示，掺杂态La1−xRuxCrO3具有较高的抗熔盐化学腐蚀性，然而其抗热振性较差，电解之后出现明显的表层机械脱落现象。上述结果表明，掺杂态La1−xRuxCrO3具备作为惰性析氧阳极材料的化学稳定性，然而需要进一步提高其热稳定性才能适用于熔盐电解用惰性阳极。