Investigations in the development of lead-free piezoelectric ceramics have recently claimed comparable properties to the lead-based ferroelectric perovskites, represented by Pb(Zr,Ti)O3, or PZT In this work, the scientific and technical impact of these materials is contrasted with the various families of “soft” and “hard” PZTs On the scientific front, the intrinsic nature of the dielectric and piezoelectric properties are presented in relation to their respective Curie temperatures (T
 C) and the existence of a morphotropic phase boundary (MPB) Analogous to PZT, enhanced properties are noted for MPB compositions in the (Na,Bi)TiO3-BaTiO3 and ternary system with (K,Bi)TiO3, but offer properties significantly lower The consequences of a ferroelectric to antiferroelectric transition well below T
 C further limits their usefulness Though comparable with respect to T
 C, the high levels of piezoelectricity reported in the (K,Na)NbO3 family are the result of enhanced polarizability associated with the orthorhombic-tetragonal polymorphic phase transition being compositionally shifted downward As expected, the properties are strongly temperature dependent, while degradation occurs through the thermal cycling between the two distinct ferroelectric domain states Extrinsic contributions arising from domains and domain wall mobility were determined using high field strain and polarization measurements The concept of “soft” and “hard” lead-free piezoelectrics were discussed in relation to donor and acceptor modified PZTs, respectively Technologically, the lead-free materials are discussed in relation to general applications, including sensors, actuators and ultrasound transducers

Lead-free piezoelectric ceramics: Alternatives for PZT?

Recent developments in cathode materials for lithium ion batteries

Potassium-sodium niobate lead-free piezoelectric materials: past, present, and future of phase boundaries.

Recent development in 2D materials beyond graphene

Future generations of electric vehicles require driving ranges of at least 300 miles to successfully penetrate the mass consumer market. A significant improvement in the energy density of lithium batteries is mandatory while also maintaining similar or improved rate capability, lifetime, cost, and safety. The vast majority of electric vehicles that will appear on the market in the next 10 years will employ nickel-rich cathode materials, LiNi1–x–yCoxAlyO2 and LiNi1–x–yCoxMnyO2 (x + y < 0.2), in particular. Here, the potential and limitations of these cathode materials are critically compared with reference to realistic target values from the automotive industry. Moreover, we show how future automotive targets can be achieved through fine control of the structural and microstructural properties.

Nickel-Rich Layered Cathode Materials for Automotive Lithium-Ion Batteries: Achievements and Perspectives

Soft Synthesis of Single‐Crystal Silicon Monolayer Sheets

The microstructural development of crystalline-oriented (K0.5Na0.5)NbO3 (KNN)-based piezoelectric ceramics during sintering was investigated. The addition of CuO as a sintering aid was found to be effective for fabricating highly oriented and dense KNN ceramics. KNN specimens containing 0.5–1.0 mol% CuO sintered at 1100°C for 1 h were found to have relative densities and pseudo-cubic {100} orientation degrees of 95% or higher. In the early stages of sintering, KNN is formed in the reaction between complementary reactants NaNbO3 and KNbO3, after which oriented grain growth proceeds at a relative density of more than 90%. In addition, the results of transmission electron microscopy observation showed that textured KNN ceramics have a unique pectinate-like domain structure with domain walls consisting of {101} planes.

Microstructural Evolution of Crystalline‐Oriented (K0.5Na0.5)NbO3 Piezoelectric Ceramics with a Sintering Aid of CuO

We used a suite of transmission electron microscopy (TEM) and associated electron spectroscopy methods to examine the local structure and changes in the electronic structure of LiNi 0.8 Co 0.15 Al 0.05 O 2 positive electrode material. We found a scattered rock-salt phase near grain surfaces and grain boundaries, where Ni 3+ turned to Ni 2+ , deduced from relative intensity ratios and fine structures of the L 2,3 white-line peaks of the transition metals. The spatial distribution of the degraded phase throughout the secondary particle was found using a scanning TEM-electron energy loss spectroscopy spectral imaging technique and multivariate analysis. The degradation process and its relationship to the surface reactions with electrolytes is discussed based on the spatial-distribution map of the degraded phases.

Capacity-Fading Mechanisms of LiNiO2-Based Lithium-Ion Batteries II. Diagnostic Analysis by Electron Microscopy and Spectroscopy

Effect of Mg-doping on the degradation of LiNiO2-based cathode materials by combined spectroscopic methods

Degradation analysis of a Ni-based layered positive-electrode active material cycled at elevated temperatures studied by scanning transmission electron microscopy and electron energy-loss spectroscopy

Kayo Horibuchi

Papers

Soft Synthesis of Single‐Crystal Silicon Monolayer Sheets

Microstructural Evolution of Crystalline‐Oriented (K0.5Na0.5)NbO3 Piezoelectric Ceramics with a Sintering Aid of CuO

Capacity-Fading Mechanisms of LiNiO2-Based Lithium-Ion Batteries II. Diagnostic Analysis by Electron Microscopy and Spectroscopy

Effect of Mg-doping on the degradation of LiNiO2-based cathode materials by combined spectroscopic methods

Degradation analysis of a Ni-based layered positive-electrode active material cycled at elevated temperatures studied by scanning transmission electron microscopy and electron energy-loss spectroscopy