Piezoelectricity is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied mechanical stress. The word piezoelectricity means electricity resulting from pressure and latent heat. It is derived from Ancient Greek πιέζω (piézō) 'to squeeze or press' and ἤλεκτρον (ḗlektron) 'amber'. The German form of the word (Piezoelektricität) was coined in 1881 by the German physicist Wilhelm Gottlieb Hankel; the English word was coined in 1883.
A perovskite is any material of formula ABX3 with a crystal structure similar to that of the mineral perovskite, which consists of calcium titanium oxide (CaTiO3). The mineral was first discovered in the Ural mountains of Russia by Gustav Rose in 1839 and named after Russian mineralogist L. A. Perovski (1792–1856). 'A' and 'B' are two positively charged ions (i.e. cations), often of very different sizes, and X is a negatively charged ion (an anion, frequently oxide) that bonds to both cations. The 'A' atoms are generally larger than the 'B' atoms. The ideal cubic structure has the B cation in 6-fold coordination, surrounded by an octahedron of anions, and the A cation in 12-fold cuboctahedral coordination. Additional perovskite forms may exist where both/either the A and B sites have a configuration of A1x-1A2x and/or B1y-1B2y and the X may deviate from the ideal coordination configuration as ions within the A and B sites undergo changes in their oxidation states.
Lead zirconate titanate, also called lead zirconium titanate and commonly abbreviated as PZT, is an inorganic compound with the chemical formula Pb[ZrxTi1−x]O3(0 ≤ x ≤ 1).. It is a ceramic perovskite material that shows a marked piezoelectric effect, meaning that the compound changes shape when an electric field is applied. It is used in a number of practical applications such as ultrasonic transducers and piezoelectric resonators. It is a white to off-white solid.
Polaritonics is an intermediate regime between photonics and sub-microwave electronics. In this regime, signals are carried by an admixture of electromagnetic and lattice vibrational waves known as phonon-polaritons, rather than currents or photons. Since phonon-polaritons propagate with frequencies in the range of hundreds of gigahertz to several terahertz, polaritonics bridges the gap between electronics and photonics. A compelling motivation for polaritonics is the demand for high speed signal processing and linear and nonlinear terahertz spectroscopy. Polaritonics has distinct advantages over electronics, photonics, and traditional terahertz spectroscopy in that it offers the potential for a fully integrated platform that supports terahertz wave generation, guidance, manipulation, and readout in a single patterned material.
Monopotassium phosphate (MKP) (also, potassium dihydrogen phosphate, KDP, or monobasic potassium phosphate) is the inorganic compound with the formula KH2PO4. Together with dipotassium phosphate (K2HPO4.(H2O)x) it is often used as a fertilizer, food additive, and buffering agent. The salt often cocrystallizes with the dipotassium salt as well as with phosphoric acid.
Potassium titanyl phosphate (KTP) is an inorganic compound with the formula K+[TiO]2+PO3−4. It is a white solid. KTP is an important nonlinear optical material that is commonly used for frequency-doubling diode-pumped solid-state lasers such as Nd:YAG and other neodymium-doped lasers.
Multiferroics are defined as materials that exhibit more than one of the primary ferroic properties in the same phase:
Barium titanate (BTO) is an inorganic compound with chemical formula BaTiO3. Barium titanate appears white as a powder and is transparent when prepared as large crystals. It is a ferroelectric, pyroelectric, and piezoelectric ceramic material that exhibits the photorefractive effect. It is used in capacitors, electromechanical transducers and nonlinear optics.
Lithium niobate is a synthetic salt consisting of niobium, lithium, and oxygen. Its single crystals are an important material for optical waveguides, mobile phones, piezoelectric sensors, optical modulators and various other linear and non-linear optical applications. Lithium niobate is sometimes referred to by the brand name linobate.
Hafnium(IV) oxide is the inorganic compound with the formula HfO
2. Also known as hafnium dioxide or hafnia, this colourless solid is one of the most common and stable compounds of hafnium. It is an electrical insulator with a band gap of 5.3~5.7 eV. Hafnium dioxide is an intermediate in some processes that give hafnium metal.
In physics, photon-induced electric field poling is a phenomenon whereby a pattern of local electric field orientations can be encoded in a suitable ferroelectric material, such as perovskite. The resulting encoded material is conceptually similar to the pattern of magnetic field orientations within the magnetic domains of a ferromagnet, and thus may be considered as a possible technology for computer storage media. The encoded regions are optically active and thus may be "read out" optically.
Bismuth ferrite (BiFeO3, also commonly referred to as BFO in materials science) is an inorganic chemical compound with perovskite structure and one of the most promising multiferroic materials. The room-temperature phase of BiFeO3 is classed as rhombohedral belonging to the space group R3c. It is synthesized in bulk and thin film form and both its antiferromagnetic (G type ordering) Néel temperature (approximately 653 K) and ferroelectric Curie temperature are well above room temperature (approximately 1100K). Ferroelectric polarization occurs along the pseudocubic direction () with a magnitude of 90–95 μC/cm2.
Lead scandium tantalate (PST) is a mixed oxide of lead, scandium, and tantalum. It has the formula Pb(Sc0.5Ta0.5)O3. It is a ceramic material with a perovskite structure, where the Sc and Ta atoms at the B site have an arrangement that is intermediate between ordered and disordered configurations, and can be fine-tuned with thermal treatment. It is ferroelectric at temperatures below 270 K (−3 °C; 26 °F), and is also piezoelectric. Like structurally similar lead zirconate titanate and barium strontium titanate, PST can be used for manufacture of uncooled focal plane array infrared imaging sensors for thermal cameras.
The Burns temperature, Td, is the temperature where a ferroelectric material, previously in paraelectric state, starts to present randomly polarized nanoregions, that are polar precursor clusters. This behaviour is typical of several, but not all, ferroelectric materials, and was observed in lead titanate (PbTiO3), potassium niobate (KNbO3), lead lanthanum zirconate titanate (PLZT), lead magnesium niobate (PMN), lead zinc niobate (PZN), K2Sr4(NbO3)10, and strontium barium niobate (SBN), Na1/2Bi1/2O3 (NBT).
Changbaiite (PbNb2O6) is a member of the oxide mineral class in which the mineral contains oxygen which is grouped along with one or two metal ion. Changbaiite is classified as a multiple Oxide XY2O6 and it generally has an ionic bond. Furthermore, it is also orthorhombic at a temperature of 25 °C and it changes to orthorhombic-tetragonal at 570 °C.
Strontium barium niobate is the chemical compound SrxBa1−xNb2O6 for 0.32≤x≤0.82.
Relaxor ferroelectrics are ferroelectric materials that exhibit high electrostriction. As of 2015, although they have been studied for over fifty years, the mechanism for this effect is still not completely understood, and is the subject of continuing research.
Sodium bismuth titanate or bismuth sodium titanium oxide (NBT or BNT) is a solid inorganic compound of sodium, bismuth, titanium and oxygen with the chemical formula of Na0.5Bi0.5TiO3 or Bi0.5Na0.5TiO3. This compound adopts the perovskite structure.
Dragan Damjanovic is a Swiss-Bosnian-Herzegovinian materials scientist. From 2008 to 2022, he was a professor of material sciences at EPFL and head of the Group for Ferroelectrics and Functional Oxides.
