150 YEARS OF PREDICTING THE ELEMENTS OF ELECTRONICS, PART 3 - Tantalum
A Few Words from Sara Shepherd, Screaming Circuits Contributing Blogger...
We hoped our previous blog posts (one and two) on the 150th anniversary of the Periodic Table would tantalize (ouch - yes. we did that) you to want to learn more, and so here we are again! Let’s explore another element vital to the world of electronics: tantalum.
Tantalum (Ta, atomic number 73) was discovered within a mineral sample in 1802 by Swedish chemist Anders Ekeberg. The element’s name comes from the Greek myth of Tantalus, who was cursed by the gods to stand forever in knee deep water below a fruit tree. When Tantalus reached for fruit, the branches always moved out of his reach, and when he bent down to take a drink, the water always vanished. Ekeberg’s inspiration to use this name came in part from his love of Greek myths and well as a result of his experiments with the element; "This metal I call tantalum,” wrote Ekeberg, “partly in allusion to its incapacity -- when immersed in acid -- to absorb any and be saturated." (Tantalum continues to be renowned for its resistance to corrosion by acids.)
Unfortunately for Ekeberg, in 1809 a well-respected English chemist named William Wollaston claimed tantalum was actually niobium, an element discovered a year before. The scientific community believed Wollaston over Ekeberg until 1846, when German mineralogist Heinrich Rose finally proved beyond doubt that tantalum and niobium were different elements, and thus restored Ekeberg’s scientific reputation.
In Wollaston’s defence, tantalum and niobium are quite difficult separate from one another. In fact, it was one hundred years after Ekeberg’s initial discovery that chemists were finally able to produce pure tantalum from a mineral sample. Werner von Bolton, a German chemist, not only produced a pure, ductile form of tantalum in 1902, but also devised a technique for producing tantalum filaments for incandescent light bulbs, creating the first metal filament on the market.
Due to its very high melting point, tantalum could be heated to incandescence without destroying itself, unlike most metals. Von Bolton’s filament was so vastly superior to all other filaments that tantalum bulbs reigned supreme from 1902 - 1909, until the arrival of ductile tungsten put an end to that application.
Despite falling from favor in the light bulb arena, tantalum’s days in the world of electronic goods were far from over. After noting the element’s tendency to form a protective oxide surface later, Tansitor Electronic Inc developed the first tantalum electrolytic capacitors with wound tantalum foils and non-solid electrolyte in 1930. Bell Laboratories followed up with this work in the early 1950’s, inventing solid electrolyte tantalum capacitors.
Today, tantalum capacitors continue to be favored over heavier and larger capacitors, such as aluminium electrolytic capacitors, for mobile phones, automotive electronics, and cameras. It has also found uses as electrodes for neon lights and AC/DC rectifiers.