The crystal structure, magnetic susceptibility as a function of temperature χ(T) in the range 5–400 K, and the hydrostatic pressure effect on χ at fixed temperatures T = 78, 150, and 300 K, were studied in perovskite-like compounds La1−xPrxCoO3 (x = 0, 0.1, 0.2, and 0.3). The obtained experimental data were analyzed using a two-level model with an energy gap Δ between the ground and excited states of the system that correspond to the spin values S = 0 and 1 for Co3+ ions. In this model, the magnetism of Co3+ ions, which determines the features of the χ (T) dependence, is ensured by the temperature-induced change in the population of the excited state. The anomalously large magnitude of the observed pressure effect is associated with the high sensitivity of Δ to changes in the lattice volume, under the influence of both hydrostatic and chemical pressures, when La is replaced by the smaller Pr ion in the considered system. Theoretical calculations of the electronic structure for the boundary compounds LaCoO3 and PrCoO3 confirm the significant increase in the excitation energy Δ with a decrease in the lattice volume, and also support the scenario of a spin crossover between the states of cobalt ions with low and intermediate spin values.

中文翻译：

---

温度和压力对 La1−xPrxCoO3 化合物中钴离子自旋态的影响

在钙钛矿类化合物中研究了晶体结构、磁化率随温度 χ(T) 在 5-400 K 范围内的变化，以及在固定温度 T = 78、150 和 300 K 下静水压力对 χ 的影响La1-xPrxCoO3（x = 0、0.1、0.2 和 0.3）。使用两能级模型分析获得的实验数据，系统的基态和激发态之间的能隙 Δ 对应于 Co3+ 离子的自旋值 S = 0 和 1。在该模型中，决定 χ (T) 依赖性特征的 Co3+ 离子的磁性由激发态总体的温度引起的变化来保证。观察到的异常大的压力效应与 Δ 对晶格体积变化的高灵敏度有关，在静水压力和化学压力的影响下，当所考虑的系统中 La 被较小的 Pr 离子取代时。边界化合物 LaCoO3 和 PrCoO3 的电子结构的理论计算证实了激发能 Δ 随着晶格体积的减小而显着增加，并且还支持具有低自旋和中等自旋的钴离子状态之间的自旋交叉的情景值。