First-principles calculations of the crystal structures, phase transition, and elastic properties of EuS have been carried out with the plane-wave pseudopotential density functional theory method. The calculated values are in very good agreement with experimental data as well as some of the existing model calculations. The dependence of the elastic constants, the aggregate elastic modulus, and the elastic anisotropy on pressure have been investigated. Moreover, the variation of the Poisson＇s ratio, Debye temperature, and the compressional and shear elastic wave velocities with pressure have been investigated for the first time. Through the quasi-harmonic Debye model, the thermal expansions, heat capacities, Grneisen parameters and Debye temperatures dependence on the temperature and pressure are obtained in the pressure range from 0 GPa to 60 GPa and temperature range from 0 K to 800 K.
PCRR教学模式是一种科学论证教学模式,即通过呈现、批判、反思、提炼等教学环节,在循环论证中推进学习进程,理解科学概念,是一种培养学生批判性思维的有效模式。通过对PCRR教学模式基本思想的分析,结合“滑动摩擦力”的内容特点,以滑动摩擦力的大小、方向、作用点等学生学习的重点和难点为论证内容,探索运用PCRR教学模式设计培养批判性思维能力教学的可行路径。The PCRR teaching model is a scientific argumentation-based teaching approach that advances the learning process through cycles of presentation, critique, reflection, and refinement. It facilitates understanding of scientific concepts and serves as an effective mode for cultivating students’ critical thinking skills. By analyzing the fundamental principles of the PCRR teaching model and incorporating the content characteristics of “sliding friction”, this study explores feasible pathways for designing instruction to cultivate critical thinking abilities, with a focus on the key and difficult learning points for students such as the magnitude, direction, and point of application of sliding friction as the subjects of argumentation.
