Gold（Au）

Gold is one of the most valuable and sought-after metals in the world. Since its discovery during ancient times, it has been utilized as jewelry, coins, and tools. Still, in today's economy, its most popular use is as jewelry. Gold is one of the more beautiful precious metals with a lustrous, yellow sheen. It has a melting point of 1,064°C, a density of 19.3 g/cc, and a vapor pressure of 10^-4 Torr at 1,132°C with its ideal evaporation temperature being around 1,400°C. It is soft, dense, malleable, ductile, and an excellent conductor of heat and electricity. Deposited films of gold are used as layers in the production of semiconductors, sensors, batteries, and data storage.

Silver（Ag）

Silver is a soft, lustrous element that belongs to the transition group of metals on the periodic table. It has a melting point of 962°C, a density of 10.5 g/cc, and vapor pressure of 10^-4 Torr at 1,105°C. Silver has been used since ancient times in countless products. It is ductile, malleable, and the most electrically conductive of all metals. It is considered a precious metal and can be found in jewelry, solders, paints, and mirrors. It is evaporated under vacuum for the production of semiconductors, sensors, fuel cells, and optical coatings.

 Platinum  ( Pt )

Platinum is one of nine precious metals on the periodic table. It has a melting point of 1,772°C, a density of 21.4 g/cc, and vapor pressure of 10^-4 Torr at 1,747°C. It is a radiant, silvery-white metal that bears a striking resemblance to palladium. It is dense, malleable, ductile, and corrosion resistant in air. Its most prominent commercial application is as a catalytic converter in vehicles. Platinum is evaporated under vacuum for the manufacture of semiconductors, fuel cells, and batteries. It is also utilized as a layer for optical coatings. Platinum is commonly found in jewelry and laboratory instruments.

 Palladium ( Pd )

Palladium is a silvery-white precious metal that bears a sharp resemblance to platinum .  It has a melting point of 1,554°C, a density of 12.038 g/cc , and a vapor pressure of 10^-4 Torr at 1,192°C. It belongs to the platinum group of metals on the periodic table. It has the lowest melting point of the elements of this group and is the least dense. Palladium is remarkably malleable, ductile, and corrosion resistant. Like platinum, its most prominent use in industry is as a catalytic converter. It can also found in jewelry and surgical instruments. Palladium is evaporated under vacuum for the manufacture of semiconductors, sensors, and data storage.