Polymerized lithium niobocene
From Halopedia, the Halo wiki
Polymerized lithium niobocene (polymerized LiNb) is a human-developed synthetic material originally created for discharging the static energy that builds up on a ships hull in Slipstream space. The material was applied by Dr. Catherine Halsey for use in the reactive metal liquid crystal layer of the MJOLNIR Powered Assault Armor, first to the MJOLNIR Mark IV and later to all subsequent models. As a disadvantage, the material's manufacturing processes involves classified "super-toxic" precursor materials and require a zero-gravity environment.
The polymerized lithium niobocene, which shares some properties with ferrocene, operates on the principles of piezoelectricity. A piezoelectric material generates an electrical charge when it is subjected to mechanical stress. Conversely, if electricity is applied to the same material, it will structurally deform. The polymerized LiNb alters its shape to a greater degree than any other known piezoelectric material. This allowed the for the incredible amplification of strength and speed required by Dr. Halsey for the MJOLNIR project. The layer of polymerized lithium niobocene flawlessly enhances the speed and power of the wearer, a sharp contrast to previous UNSC exoskeletons which required powered motors to allow the soldiers mobility and reflexes. The polymerized lithium niobocene is "poured" directly into the armor's capillary system, where microelectric fields direct crystallization geometries. The layer is amorphous, yet fractally scales and amplifies force, doubling lifting capacity and decreasing reaction time by a factor of five.
Because of this advancement, the design of the MJOLNIR armor more closely resembles an actual suit of armor, as opposed to a powered exoskeleton. On one level the soldier moves the suit and in return the suit moves the soldier. This allowed for an incredibly compact design when compared to the previous incarnations. This is a significant advancement of cybernetic technology, truly melding man and machine together. Spartan John-117 and his team needed under an hour of drilling to adapt to moving with the increased speed and power granted by this technology. Dr. Halsey, the suit's designer, considered this to be the most important feature of the armor, and it is arguably the most dangerous. The system is so reactive that a normal human cannot wear the suit without injuring or killing him/herself. Only an augmented Spartan can safely wear MJOLNIR armor.
Spartan Kelly-087's initial remark upon first donning the suit was: "Flawless amplification of speed and power. It's like I've been training in this suit for years." Spartan Samuel-034 simply stated: "I think I'm in love."