Han purple and Han blue
[2] In 2006 scientists at Stanford, Los Alamos National Laboratory and the Institute for Solid State Physics (University of Tokyo), showed that Han purple "loses a dimension" under suitable conditions when it enters a new state, as a Bose-Einstein Condensate.
The researchers noted that "We have shown, for the first time, that the collective behavior in a bulk three-dimensional material can actually occur in just two dimensions.
Low dimensionality is a key ingredient in many exotic theories that purport to account for various poorly understood phenomena, including high-temperature superconductivity, but until now there were no clear examples of 'dimensional reduction' in real materials," said Ian FisherOther research team members alluded to potential applications to quantum computing.
In conventional computers, electron charges transport information, but electron spin might in the future play a similar role in "spintronic" devices: "Spin currents are capable of carrying far more information than a conventional charge current—which makes them the ideal vehicle for information transport in future applications such as quantum computing," stated first author Suchitra Sebastian.
Noted Fisher: "Our research group focuses on new materials with unconventional magnetic and electronic properties.
Han Purple was first synthesized over 2,500 years ago, but we have only recently discovered how exotic its magnetic behavior is.
[6] Manufacturing depends on the raw materials, their ratios, fluxes, temperature, atmosphere, and reaction time.
[4] Production seems to have been focused in northern China, around 200–300 km (120–190 mi) north of the city of Xi'an.
[10] The role of lead is:[2] The preparation of Han blue using malachite, silica and witherite as raw minerals also releases carbon dioxide and water vapor as by-products according to the following reaction:[2] The solid-state reaction to produce barium copper silicates starts at roughly 900 °C.
[2][4] Han blue forms when an excess of silica is present and a longer reaction time is allowed.
[11] Independent innovation in China would still have been needed to replace calcium with barium[11] (the Han pigments start to form at 100 – 200°C higher than the Egyptian blue).
[14] The lead is used by pigment maker to lower the melting point of the barium in Han Purple.
Berke (2007)[2] believes that political changes stopped the distribution of the pigments as the Chinese Empire was split at the end of the Han period.
[2] The Han pigments consist of varying combinations of blue, purple and colorless components.
[2] These are compact bodies (solid sticks/rods) with shades ranging from light blue to dark purple.
[18] The warriors were fired at the same temperature as that needed for the manufacture of Han purple (950–1,050 °C [1,740–1,920 °F]), so the same kilns may have been used for both processes.
[2][1] Smaller painted pottery figurines have been found e.g. the Western Han dynasty Chu Tombs, Xuzhou, Jiangsu Province[19] and in the Han dynasty Yangling tombs of Emperor Liuqi and his Empress (156–141 BC).
[13] Due to the instability of Han purple, it shows significant signs of weathering on archaeologically excavated artifacts.
[3] Two other synthetic blue barium copper silicate compounds have been found in trace amounts, but are as yet unnamed.
