Material Science Assignment.docx

Seth Adriel R. Baldovino

August 22, 2017

T3B

MatScie Assignment

Materials composing the Smartphone

In line with the field of chemistry, smartphones are very much linked to the roots of the said science. Of the 83 stable (nonradioactive) elements in the periodic table, at least 70 of them can be found in smartphones. This accounts for 84% of all of the stable elements. Metals are what make smartphones so “smart.” An average smartphone may contain up to 62 different types of metals. One rather obscure group of metals—the rare-earth metals—plays a vital role. These rare-earth metals include scandium and yttrium, as well as elements 57–71. Elements 57–71 are known as the lanthanides, because they begin with the element lanthanum. The lanthanides often appear as the first of two free-floating rows located at the bottom of the periodic table. Scandium and yttrium are included in the rare-earth metals because their chemical properties are similar to those of the lanthanides. In terms of its glass, the smartphone’s glass is made from aluminium oxide and silicon dioxide with an ultra-thin layer of indium tin oxide added so you can touch the screen without damaging it. The third most common material found is plastic. Plastic is often used in the case in place of metal. The use of plastic in a cell phone makes it more resistant to damagewhen you drop or scratch it. Plastic is also used since it can stand up to all but the most extreme temperature fluctuations. The material is very flexible, and it does not cause reception problems when you're trying to find a cell signal. Meanwhile, majority of today’s phones use lithium ion batteries. These batteries tend to use lithium cobalt oxide as the positive electrode in the battery (though other transition metals are sometimes used in place of cobalt), whilst the negative electrode is formed from carbon in the form of graphite. It will also have an organic solvent to act as the electrolytic fluid. Lastly, a wide range of elements and compounds are used in the electronics of a phone. The chip, the processor of the phone, is made from pure silicon, which is then exposed to oxygen and heat in order to produce a film of silicon dioxide on its surface. Parts of this silicon dioxide layer are then removed where current will be required to flow. Silicon does not conduct electricity without being ‘doped’ with other elements; this process involves the silicon being bombarded with a variety of different elements, which can include phosphorus, antimony, arsenic, boron, indium or gallium. Different types of semiconductor (P or N) are produced depending on the element used, with boron being the most common type of P-type dopant.

The micro-electrical components and wiring in the phone are composed mainly of copper, gold, and silver. Tantalum is also used, being the main component of micro-capacitors. A range of other elements, including platinum and palladium are also used, but detail on the specific applications of these was a little tricker to track down! Solder is used to join electrical components together – this was, in years past, usually composed of tin and lead, but in recent years lead-free alternatives have been sought, many of which use a combination of tin, silver and copper. The microphone and speaker of the phone both contain magnets, which are usually neodymium-iron-boron alloys, though dysprosium and praseodymium are often also present in the alloy. These are also found in the vibration unit of the phone.