Review on thermal energy storage with phase change: materials, heat transfer analysis and applications

A large body of work has been reported in the last 5 years on the development of lead-free piezoceramics in the quest to replace lead–zirconate–titanate (PZT) as the main material for electromechanical devices such as actuators, sensors, and transducers. In specific but narrow application ranges the new materials appear adequate, but are not yet suited to replace PZT on a broader basis. In this paper, general guidelines for the development of lead-free piezoelectric ceramics are presented. Suitable chemical elements are selected first on the basis of cost and toxicity as well as ionic polarizability. Different crystal structures with these elements are then considered based on simple concepts, and a variety of phase diagrams are described with attractive morphotropic phase boundaries, yielding good piezoelectric properties. Finally, lessons from density functional theory are reviewed and used to adjust our understanding based on the simpler concepts. Equipped with these guidelines ranging from atom to phase diagram, the current development stage in lead-free piezoceramics is then critically assessed.

Perspective on the Development of Lead-free Piezoceramics

Phase change materials for thermal energy storage

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

Since the discovery of superconductivity above 30 K by Bednorz and M\"uller in the La copper oxide system, the critical temperature has been raised to 90 K in Y${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ and to 110 and 125 K in Bi-based and Tl-based copper oxides, respectively. In the two years since this Nobel-prize-winning discovery, a large number of electronic structure calculations have been carried out as a first step in understanding the electronic properties of these materials. In this paper these calculations (mostly of the density-functional type) are gathered and reviewed, and their results are compared with the relevant experimental data. The picture that emerges is one in which the important electronic states are dominated by the copper $d$ and oxygen $p$ orbitals, with strong hybridization between them. Photon, electron, and positron spectroscopies provide important information about the electronic states, and comparison with electronic structure calculations indicates that, while many features can be interpreted in terms of existing calculations, self-energy corrections ("correlations") are important for a more detailed understanding. The antiferromagnetism that occurs in some regions of the phase diagram poses a particularly challenging problem for any detailed theory. The study of structural stability, lattice dynamics, and electron-phonon coupling in the copper oxides is also discussed. Finally, a brief review is given of the attempts so far to identify interaction constants appropriate for a model Hamiltonian treatment of many-body interactions in these materials.

Electronic structure of the high-temperature oxide superconductors

The microstructural, dielectric and piezoelectric properties of the (Na0.5Bi0.5)TiO3–NaNbO3 and (K0.5Bi0.5)TiO3–KNbO3 systems were studied in order to find new lead-free piezoelectric ceramic materials. In the (1-X) (K0.5Bi0.5)TiO3–(X) KNbO3 system, it was confirmed from the measurements of the electromechanical coupling factor, Kp, that piezoelectricity occurred within the wide compositional range between X=0 and 0.35. The sample with X=0.075 showed a maximum Kp of 15.1%. However, the expected morphotropic phase boundaries were not found in the (Na0.5Bi0.5)TiO3 or (K0.5Bi0.5)TiO3 rich side of the solid solution systems.

https://iopscience.iop.org/article/10.1143/JJAP.40.5703/pdf

Dielectric and Piezoelectric Properties of (A0.5Bi0.5)TiO3–ANbO3 (A=Na, K) Systems

MoSe2 layers formed at the interface between Cu-In-Ga-Se and Mo layers were studied by X-ray diffraction and high resolution transmission electron microscopy. Various composition Cu-In-Ga-Se films such as Se, Cu-Se, In-Ga-Se and Cu-rich Cu-In-Ga-Se were deposited on Mo coated glass substrates by physical vapor deposition. For the case of the Se/Mo interface, a MoSe2 layer of about 100 A thickness was observed. The c-axis of the MoSe2 grains were found to be oriented normal to the surface of Mo layer. For the Cu-Se/Mo and Cu-rich Cu-In-Ga-Se/Mo structures, the thickness of the MoSe2 layers found at the interface was thin. For the case of the In-Ga-Se/Mo structure, a 0.1 µm thick interfacial MoSe2 layer was observed whose c-axis was oriented parallel to the Mo surface. The microstructure of the In-Ga-Se/Mo film was similar to that of the device quality CIGS/Mo structure deposited by the "3-stage" process. A formation mechanism for the MoSe2 layers occurring during the "3-stage" process is proposed.

https://iopscience.iop.org/article/10.1143/JJAP.37.L71/pdf

MoSe 2 layer formation at Cu(In,Ga)Se 2/Mo Interfaces in High Efficiency Cu(In1- xGa x)Se 2 Solar Cells

High-quality (K,Na)NbO3 thin films were successfully deposited on a (100) SrTiO3 (STO) substrate by pulsed laser deposition. High-density KNbO3 (KN), (K0.5Na0.5)NbO3 (KNN) and NaNbO3 (NN) ceramic targets were prepared by spark plasma sintering (SPS). The crystallographic analyses of the film were performed by conventional X-ray diffraction (XRD) analysis and rocking curve measurement. The XRD reciprocal space map was also measured to determine the lattice constants of the film and analyze the crystallographic relationship between the grown film and the STO substrate. The fluctuation change in the orientation of crystals in the grown film decreased and the smoothness of the film surface improved with increasing sodium content of the film. For the NN films, the full width at half maximum (FWHM) of the rocking curve was as small as 0.12°. The XRD reciprocal space map measurements showed that the lattices of the KN and KNN films relaxed on the STO substrate but the NN film was restricted to it.

https://iopscience.iop.org/article/10.1143/JJAP.43.6627/pdf

Pulsed laser deposition of high-quality (K, Na)NbO3 thin films on SrTiO3 substrate using high-density ceramic targets

New layered perovskite compounds, Srn+1VnO3n+1 (n=1, 2 and 3) and SrVO3(n=∞ ), were synthesized and the physical properties of the compounds with n=1, 2 and ∞ were investigated Sr2VO4 was semiconductive and antiferromagnetic, but a weak ferromagnetic contribution to the susceptibility was observed below 45 K However, Sr3V2O7, exhibited a metallic electrical conduction and a Pauli-paramagnetism SrLaVO4 was also successfully synthesized and was found to be semiconductive The crystal structures and electrical and magnetic properties of Srn+1VnO3n+1 (n=1, 2, 3 and ∞ ) and SrLaVO4 were compared

Layered perovskite compounds Srn+1VnO3n+1 (n=1, 2, 3, and

A chalcopyrite-type compound, for instance, CuInS₂ or CuGaS₂, is prepared by subjecting a Group I - III oxide composition, containing at least one of the Group Ib element, for instance copper (Cu), and at least one of the Group IIIb element, for instance indium (In) or gallium (Ga) to a heat treatment under a reducing atmosphere containing the Group VIb element, for instance sulfur (S) or selenium (Se), or under an atmosphere containing a reducing compound of the Group VIb element, thereby converting said oxide composition into a chalcopyrite-type compound.

Takahiro Wada

Papers

Dielectric and Piezoelectric Properties of (A0.5Bi0.5)TiO3–ANbO3 (A=Na, K) Systems

MoSe 2 layer formation at Cu(In,Ga)Se 2/Mo Interfaces in High Efficiency Cu(In1- xGa x)Se 2 Solar Cells

Pulsed laser deposition of high-quality (K, Na)NbO3 thin films on SrTiO3 substrate using high-density ceramic targets

Layered perovskite compounds Srn+1VnO3n+1 (n=1, 2, 3, and

Method for preparing chalcopyrite-type compound