About Titanates

Aluminum Titanate

Titanates are compounds containing titanium, oxygen, and at least one additional metallic element. Some of the most common titanates are strontium titanate, barium titanate, calcium titanate, and dysprosium titanate.

Strontium titanate, at room temperature, is a centrosymmetric paraelectric material with a perovskite structure. However, at low temperatures it nears a ferroelectric phase transition with a very large dielectric constant, but remains paraelectric down to the lowest temperatures measured. It was long thought to be an entirely artificial material until 1982 when its natural counterpart tausonite was recognized. Tausonite remains an extremely rare mineral in nature, occurring as extremely small crystals. Strontium titanate’s most important application has been in its synthesized form; it is occasionally used as a diamond alternative, in precision optics, in varistors, and in advanced ceramics. Strontium titanate is both much denser and much softer than diamond. Its crystal system is cubic and its refractive index is nearly identical to that of diamond, but the dispersion (the optical property responsible for the "fire" of cut gem stones) of strontium titanate is over four times higher, resulting in an excess of fire when compared to diamond.

Synthetic strontium titanate is usually transparent and colorless, but it can be doped with certain rare earth or transition metals to produce red, yellow, brown, and blue hues. Natural tausonite is usually translucent to opaque, in shades of reddish brown, dark red, or grey. Both have an diamond-like luster. Synthetic strontium titanate has a very large dielectric constant and is used in high-voltage capacitors. At 0.35 K strontium titanate is superconductive and was the first insulator and oxide in which this property was studied. At temperatures lower than 105 K, its cubic structure transforms to tetragonal, making it an excellent substrate for epitaxial growth of high-temperature superconductors and many oxide-based thin films. Strontium titanate can be used as optical windows and high-quality sputtering targets.

Strontium titanate is also periodically manufactured for use in jewelry. It is one of the most costly of diamond alternatives, and due to its rarity collectors may pay a premium for large specimens. As a diamond substitute, strontium titanate is most deceptive when mingled with melée and when it is used as the base material for a composite or doublet stone. Under the microscope, gemologists distinguish strontium titanate from diamond by the former's softness and excess dispersion, and occasional gas bubbles which are remnants of synthesis. Doublets can be detected by a join line at the girdle and flattened air bubbles or glue visible within the stone at the point of bonding.

Barium titanate is an oxide composed of barium and titanium. Barium titanate appears as white powder or transparent crystals. It is insoluble in water, but will dissolve in concentrated sulfuric acid. It is a ferroelectric ceramic material, with a photorefractive effect and piezoelectric properties. Solid barium titanate has five phases: hexagonal, cubic, tetragonal, orthorhombic, and rhombohedral crystal structure. All of the crystal structures with the exception of the cubic exhibit the ferroelectric effect. Barioperovskite is a very rare natural analogue of barium titanate, found as micro-inclusions in benitoite. Adding of inclusions of barium titanate to tin has been shown to create material with a higher visco-elastic stiffness than that of diamonds.

Barium titanate can be manufactured by liquid phase sintering of barium carbonate and titanium dioxide, sometimes with other materials for doping. Barium titanate is often mixed with strontium titanate and is used as a dielectric material for ceramic capacitors and as a piezoelectric material for microphones and other transducers. Polycrystalline barium titanate displays positive temperature coefficient, making it a useful material for thermostats and self-regulating electric heating systems. High purity barium titanate powder is reported to be a key component of new barium titanate capacitor-based alternative energy storage systems for use in electric vehicles.

Barium titanate crystals can be used in nonlinear optics. The material has high beam-coupling gain, and can be operated at visible and near-infrared wavelengths. It has the highest reflectivity of the materials used for self-pumped phase conjugation applications. Thin films of barium titanate display electro-optic modulation to frequencies over 40 GHz. The pyro-electric and ferroelectric properties of barium titanate are exploited in some types of uncooled sensors for thermal cameras.

Calcium titanate is a chemical compound and a mineral known as perovskite, named after Russian mineralogist, L. A. Perovski (1792-1856). Calcium titanate can aid in the integration of biomaterials such as bone implants in hip replacement surgery. It has low dielectric loss, especially at microwave frequencies and is therefore used as dielectric material in ceramic capacitors.

Dysprosium titanate is a ceramic titanate with pyrochlore structure and is a "spin ice" material. In 2009, dysprosium titanate was observed to have quasi-particles resembling magnetic monopoles at low temperature and high magnetic field. Dysprosium titanate is also being investigated as a new material for nuclear reactor control rods.

Recent Research & Development for Titanates

Adsorption of Cu2+ Ions from Aqueous Solutions on Nano-Titanate Engelhard Titanosilicate-2 (ETS-2)., Rezaei, Sabereh, and Kuznicki Steven M. , J Nanosci Nanotechnol, 2018 May 01, Volume 18, Issue 5, p.3619-3623, (2018)

Unexpectedly high piezoelectricity of Sm-doped lead zirconate titanate in the Curie point region., Seshadri, Shruti B., Nolan Michelle M., Tutuncu Goknur, Forrester Jennifer S., Sapper Eva, Esteves Giovanni, Granzow Torsten, Thomas Pam A., Nino Juan C., Rojac Tadej, et al. , Sci Rep, 2018 Mar 07, Volume 8, Issue 1, p.4120, (2018)

Tunable Dielectric Properties of Poly(vinylidenefluoride-co-hexafluoropropylene) Films with Embedded Fluorinated Barium Strontium Titanate Nanoparticles., Han, Wooje, Kim Taehee, Yoo Byungwook, and Park Hyung-Ho , Sci Rep, 2018 Mar 06, Volume 8, Issue 1, p.4086, (2018)

Fabrication and characterization of highly porous barium titanate based scaffold coated by Gel/HA nanocomposite with high piezoelectric coefficient for bone tissue engineering applications., Ehterami, Arian, Kazemi Mansure, Nazari Bahareh, Saraeian Payam, and Azami Mahmoud , J Mech Behav Biomed Mater, 2018 Mar, Volume 79, p.195-202, (2018)

Titanate Fibroin Nanocomposites: A Novel Approach for the Removal of Heavy-Metal Ions from water., Magrì, Davide, Caputo Gianvito, Perotto Giovanni, Scarpellini Alice, Colusso Elena, Drago Filippo, Martucci Alessandro, Athanassiou Athanassia, and Fragouli Despina , ACS Appl Mater Interfaces, 2018 Jan 10, Volume 10, Issue 1, p.651-659, (2018)

Intriguing structural and magnetic properties correlation study on Fe3+-substituted calcium-copper-titanate., Pansara, P R., Raval P Y., Vasoya N H., Dolia S N., and Modi K B. , Phys Chem Chem Phys, 2018 Jan 03, (2018)

Few-layered titanate nanosheets with large lateral size and surface functionalization: potential for the controlled exfoliation of inorganic-organic layered composites., Nakada, Gentoku, Imai Hiroaki, and Oaki Yuya , Chem Commun (Camb), 2018 Jan 02, Volume 54, Issue 3, p.244-247, (2018)

Photocatalysis of bisphenol A by an easy-settling titania/titanate composite: Effects of water chemistry factors, degradation pathway and theoretical calculation., Zhao, Xiao, Du Penghui, Cai Zhengqing, Wang Ting, Fu Jie, and Liu Wen , Environ Pollut, 2018 Jan, Volume 232, p.580-590, (2018)

Digital to analog resistive switching transition induced by graphene buffer layer in strontium titanate based devices., Wan, Tao, Qu Bo, Du Haiwei, Lin Xi, Lin Qianru, Wang Da-Wei, Cazorla Claudio, Li Sean, Liu Sidong, and Chu Dewei , J Colloid Interface Sci, 2018 Feb 15, Volume 512, p.767-774, (2018)

Synthesis of Biocompatible Titanate Nanofibers for Effective Delivery of Neuroprotective Agents., Ozkizilcik, Asya, Williams Roger, Z Tian Ryan, Muresanu Dafin F., Sharma Aruna, and Sharma Hari S. , Methods Mol Biol, 2018, Volume 1727, p.433-442, (2018)

Perovskite-type calcium titanate nanoparticles as novel matrix for designing sensitive electrochemical biosensing., Wang, Lei, Li Juan, Feng Mengjie, Min Lingfeng, Yang Juan, Yu Suhua, Zhang Yongcai, Hu Xiaoya, and Yang Zhanjun , Biosens Bioelectron, 2017 Oct 15, Volume 96, p.220-226, (2017)

The fabrication and characterization of barium titanate/akermanite nano-bio-ceramic with a suitable piezoelectric coefficient for bone defect recovery., Shokrollahi, H, Salimi F, and Doostmohammadi A , J Mech Behav Biomed Mater, 2017 Oct, Volume 74, p.365-370, (2017)

Hierarchically structured lithium titanate for ultrafast charging in long-life high capacity batteries., Odziomek, Mateusz, Chaput Frédéric, Rutkowska Anna, Świerczek Konrad, Olszewska Danuta, Sitarz Maciej, Lerouge Frédéric, and Parola Stephane , Nat Commun, 2017 May 26, Volume 8, p.15636, (2017)