The lithium niobate used in an ultrasonic transducer for liquid metal fast nuclear reactors is prone to a reduction leading to a rapid short circuit of the sensor in operating conditions. Oxygen consumption on stainless steel sensor’s walls was suspected to be the cause of the reduction. Impedance spectroscopy monitoring around 600 °C under different O₂ partial pressures shows that the reduction limit is above the equilibrium pressure of iron oxides. As the housing material (304L) cannot be easily changed, various coating solutions enhancing the passivation of the steels were investigated. Sol–gel lanthanum coatings show the best behavior when tested by TGA at 800 °C. However, in situ monitoring of the oxygen consumption by an oxygen sensor close to operating condition shows that it was not enough protective.

液态金属快核反应堆超声波换能器中使用的铌酸锂易于减少，导致传感器在运行条件下快速短路。不锈钢传感器壁上的氧气消耗被怀疑是减少的原因。在不同 O ₂分压下在 600 °C 附近的阻抗谱监测表明，还原极限高于氧化铁的平衡压力。由于外壳材料 (304L) 不易改变，因此研究了各种增强钢钝化的涂层溶液。溶胶-凝胶镧涂层在 800 °C 下通过 TGA 测试时表现出最佳性能。然而，通过接近操作条件的氧传感器对氧消耗的原位监测表明它没有足够的保护作用。