Polyanionic clustering and electronic properties of the expanded equiatomic liquid alloy cesium-lead

We present measurements of the electrical dc‐conductivity σ of the solid and liquid equiatomic Zintl‐alloy CsPb as a function of temperature in the range from 553 K to 2023 K. Due to significant charge transfer the alloy shows semiconducting behaviour. In the solid state the conductivity increases continuously from 0.2 Ω−1 cm−1 at 553 K up to 5 Ω−1 cm−1 at 800 K, where a drastic increase of σ is observed which is due to a rotor phase transition as discovered by Price, Saboungi et al. [1, 2]. In the liquid state (melting temperature Tm ≈︁ 870 K), σ reaches a maximum value of 1000 Ω−1 cm−1 around 1400 K. In addition, neutron diffraction measurements were carried out on the liquid from temperatures near the melting point up to 1900 K. The total Faber‐Ziman structure factors S(Q) exhibit a distinct prepeak remaining even up to the highest temperatures measured. This prepeak at 0.88–0.73 Å−1 is indicative of intermediate range ordering. We conclude that polyanions survive not only the melting process, but also persist through the whole temperature range up to about 1000 K above the melting point. RMC simulations were used to generate three‐dimensional models of the liquid and to determine the partial structure factors and pair correlation functions. With increasing temperature, the size of the polyanion clusters undergoes significant changes.