Terbium

Terbium is a chemical element with the symbol Tb and atomic number 65. It is a silvery-white rare earth metal that can be bent and stretched. Terbium belongs to a group of elements called the lanthanides and is very eager to give away electrons, reacting with water to release hydrogen gas.

Swedish chemist Carl Gustaf Mosander discovered terbium in 1843. He found it hidden inside a compound called yttrium oxide. Terbium was finally separated in pure form much later, when scientists developed special methods called ion exchange techniques.

Terbium has many useful applications. It is added to certain materials to improve their properties in solid-state devices and helps keep fuel cells stable at high temperatures. When mixed with other elements to form an alloy called Terfenol-D, terbium helps create materials that change size in response to magnetic fields. This makes it valuable for use in devices like actuators, naval sonar systems, and sensors.

One of the biggest uses of terbium is in green phosphors, which are materials that glow in the dark. Terbium oxide is used in fluorescent lamps and in the screens of old television and computer monitors. When combined with blue and red phosphors, terbium helps create bright, efficient white light used in indoor lighting.

Characteristics

Terbium is a shiny, silvery-white metal that is soft and can be shaped easily. It is part of a group of metals called rare earth elements. This metal stays stable in air and has a special way its atoms are arranged.

Terbium glows brightly, especially in yellow and green colors, which makes it useful in some lighting applications. It can react with water and many other substances, which means it changes when it meets them. Scientists often study terbium in labs because of these interesting properties.

History

A Swedish chemist named Carl Gustaf Mosander discovered terbium in 1843. He found it mixed with another material called yttrium oxide. Both terbium and some other elements are named after a village in Sweden called Ytterby. It took many years and new science methods before scientists could fully separate and study terbium.

Early scientists had a hard time telling terbium apart from another element called erbium. They used different chemicals to try to separate them, but it was very difficult. It wasn’t until later that they had better tools to study these elements and understand them correctly.

Occurrence

Terbium is found together with other rare earth elements in many minerals, such as monazite and xenotime. It is not very common in the Earth's crust, with an estimated amount of 1.2 mg per kilogram.

Scientists have also found terbium in the atmosphere of a planet called KELT-9b, which is far outside our Solar System.

The largest amounts of terbium used commercially come from special clays in southern China. There are also smaller amounts in minerals like bastnäsite and monazite. In 2018, a very large supply of terbium was found near Japan's Minamitori Island, enough to meet the world's needs for many years.

Production

To obtain terbium, minerals that contain it are crushed and treated with hot, strong sulfuric acid. This creates water-soluble compounds. The solution is then treated with ammonium oxalate to form solid compounds that can be heated to create oxides. These oxides are dissolved in nitric acid, which leaves behind one of the main components, cerium.

The best way to separate terbium from other rare earth elements is using ion exchange. In this process, the elements stick to a special material and are later washed off using certain chemicals. Finally, terbium metal is made by using heat and chemicals to remove impurities.

In 2020, the world needed about 340 tonnes of terbium each year. There are large amounts of rare earth minerals available globally.

Applications

Terbium is used to improve certain materials, like calcium fluoride, calcium tungstate, and strontium molybdate. These materials help make solid-state devices work better. Terbium also helps keep fuel cells stable when they get very hot.

Terbium is part of special mixtures called alloys and is used to make electronic devices. One important mixture, called Terfenol-D, changes size when a magnetic field is nearby. This helps in naval sonar, sensors, and other devices that need to move or sense things. Terbium can also make certain lights glow brightly, which is useful in old-style TV screens and energy-saving lights. Scientists even used terbium to study a single iron atom in great detail in 2023.

Safety

Terbium, like many rare earth elements, is not well studied for its effects on health and the environment. There are not many rules about safe levels of exposure to terbium, and it is not considered a dangerous substance by certain international standards.

Some research shows that terbium can build up in the environment and may harm fish and plants. Very high amounts of terbium might make other harmful substances more dangerous to plant cells.