Foreword Acknowledgements Definitions of symbols used 1. Some fundamentals 2. The harmonic approximation and lattice dynamics of very simple systems 3. Dynamics of diatomic crystals: general principles 4. How far do the atoms move? 5. Lattice dynamics and thermodynamics 6. Formal description 7. Acoustic modes and macroscopic elasticity 8. Anharmonic effects and phase transitions 9. Neutron scattering 10. Infrared and Raman spectroscopy 11. Formal quantum mechanical description of lattice vibrations 12. Molecular dynamics simulations Appendices Problems Bibliography Index.

Introduction to Lattice Dynamics

Multicomponent high-entropy zirconates with comprehensive properties for advanced thermal barrier coating

Rare-earth tantalates and niobates (RE3TaO7 and RE3NbO7) have been considered as promising candidate thermal barrier coating (TBC) materials in next generation gas-turbine engines due to their ultra-low thermal conductivity and better thermal stability than yttria-stabilized zirconia (YSZ). However, the low Vickers hardness and toughness are the main shortcomings of RE3TaO7 and RE3NbO7 that limit their applications as TBC materials. To increase the hardness, high entropy (Y1/3Yb1/3Er1/3)3TaO7, (Y1/3Yb1/3Er1/3)3NbO7, and (Sm1/6Eu1/6Y1/6Yb1/6Lu1/6Er1/6)3(Nb1/2Ta1/2)O7 are designed and synthesized in this study. These high entropy ceramics exhibit high Vickers hardness (10.9–12.0 GPa), close thermal expansion coefficients to that of single-principal-component RE3TaO7 and RE3NbO7 (7.9×10−6-10.8×10−6C−1 at room temperature), good phase stability, and good chemical compatibility with thermally grown Al2O3, which make them promising for applications as candidate TBC materials.

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High entropy defective fluorite structured rare-earth niobates and tantalates for thermal barrier applications

A review on failure mechanism of thermal barrier coatings and strategies to extend their lifetime

Improving device lifetime and stability remains the stumbling block of the commercialization of hybrid perovskite-based devices (HPDs). Although extensive efforts have been paid, thermal property, one of the most crucial parameters in conventional solid-state electronic devices, has rarely been studied for HPDs. Here, we investigate the temperature-dependent ultralow thermal conductivity and ultrahigh thermal expansion of single-crystalline MAPbX3 (MA = CH3NH3), which are found distinct from traditional thin-film solar cells materials. Particularly, for MAPbI3, thermal conductivity is observed being only 0.3 W·m–1·K–1 and linear thermal expansion coefficient along [100] direction is as high as 57.8 × 10–6 K–1 (tetragonal) and much higher at the structural phase transition point. We attribute the ultralow thermal conductivity and ultrahigh thermal expansion to the weak chemical bonds associated with the soft perovskite materials. These unique properties can be very challenging for the multilayer device des...

Ultralow Thermal Conductivity and Ultrahigh Thermal Expansion of Single-Crystal Organic–Inorganic Hybrid Perovskite CH3NH3PbX3 (X = Cl, Br, I)

Thermal barrier coatings (TBCs) are one of the most important materials in gas turbine to protect the high temperature components. RETa3O9 compounds have a defect-perovskite structure, indicating that they have low thermal conductivity, which is the critical property of TBCs. Herein, dense RETa3O9 bulk ceramics were fabricated via solid-state reaction. The crystal structure was characterized by X-ray diffraction (XRD) and Raman Spectroscope. Scanning electron microscope (SEM) was used to observe the microstructure. The thermal physics properties of RETa3O9 were studied systematically, including specific heat, thermal diffusivity, thermal conductivity, thermal expansion coefficients and high-temperature phase stability. The thermal conductivities of RETa3O9 are very low (1.33-2.37 W/m.K, 373-1073 K), which are much lower than YSZ and La2Zr2O7; and the thermal expansion coefficients range from 4.0×10-6 K−1 to 10.2×10-6 K−1 (1273 K), which is close to La2Zr2O7 and YSZ. According to the differential scanning calorimetry (DSC) curve there is not phase transition at the test temperature. Due to the high melting point and excellent high-temperature phase stability with these oxides, RETa3O9 ceramics were promising candidate materials for TBCs.

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Lin Chen

Papers

Synthesis and thermophysical properties of RETa3O9 (RE = Ce, Nd, Sm, Eu, Gd, Dy, Er) as promising thermal barrier coatings

Thermal expansion performance and intrinsic lattice thermal conductivity of ferroelastic RETaO4 ceramics

Potential thermal barrier coating materials: RE3NbO7 (RE=La, Nd, Sm, Eu, Gd, Dy) ceramics

Simultaneous Enhancement of Thermoelectric Performance and Mechanical Properties in Bi2Te3 via Ru compositing

Influence of ZrO2 alloying effect on the thermophysical properties of fluorite-type Eu3TaO7 ceramics