Historical research guide · 1119 · 2019
Piezoelectricity-induced Room Temperature Superconductor
Salvatore Cezar Pais · US Department of the Navy
In one minute
This is the earliest of Pais's superconductor filings and the one that states the mechanism most plainly. His wire is inside out compared with an ordinary conductor: a bulk insulating core, such as Teflon, with a thin metal or ceramic coating around it, the coating no thicker than the London penetration depth. Pulse a current through that coating while shaking the wire hard — mechanically, by plucking it with a non-conductive pick, or electrically, by making a lead zirconate titanate coating vibrate itself through the piezoelectric effect — and Pais argues the interface between coating and core becomes superconducting at room temperature. His case is that the three things a superconductor must do are each separately achievable this way: the vibrating charged surface generates enough magnetic flux to expel an applied field, giving the Meissner effect; the uncharged core forces the electric field to vanish, giving zero resistance; and the far-from-equilibrium shaking self-organises the electrons into a coherent state. The application was abandoned.
Connection
Chapter 8 follows the Navy filings as a documented engineering programme, and this one is where the family's central idea is set down before the later continuation reworded it: that what makes a material superconduct is less its chemistry than what is done to it — accelerated vibration of charged matter held away from thermal equilibrium. The same non-equilibrium argument runs through Pais's other filings, and the patent names its own experimental touchstone, the light-induced superconductivity seen in potassium-doped fullerene.
From the source
The invention is a wire built the opposite way round from a normal conductor: a bulk insulating core, such as Teflon or another non-conductive polymer, carrying a thin coating of a normal metal such as aluminium or of lead zirconate titanate ceramic, with the coating on the order of the London penetration depth in thickness.Background and Description, wire 100, insulator core 110 and coating 120; Claims 1, 2, 4 and 7
Superconductivity is induced not by the chemistry of the material but by what is done to it — a pulsed current passed through the coating while the wire is abruptly vibrated, by a non-conductive pick, by an electromagnetic plucking coil, or by applying a potential across a piezoelectric coating so the wire shakes itself.Summary and Description, means of vibration; Claims 1, 2 and 6
The Meissner condition is written as an inequality in which the flux from the wire current plus a term in the surface charge density, the vibration amplitude, the square of the vibration frequency and the vibration interval must exceed the applied magnetic induction. Pais notes that this expression contains no temperature and therefore no critical temperature, and that the vibration frequency is the only quantity entering non-linearly.Description, Equation 2 and the paragraph following it
Perfect conductivity is argued from the geometry: because only the coating carries charge and the core does not, the magnetic induction inside the bulk is zero and so is its time derivative, Faraday's law then makes the curl of the electric field vanish, and with a current still flowing the field can only be zero if the resistivity is.Description, derivation of the London condition from the Maxwell equations
For the third requirement, macroscopic quantum coherence, Pais invokes what he calls the Prigogine effect from his own 2015 paper in the International Journal of Space Science and Engineering: a chaotic medium self-organises into an orderly state given high non-linearity, an abrupt departure far from thermodynamic equilibrium, and a sustaining energy flux — here supplied by the intermittent vibration, which he argues delays decoherence by never letting the system relax.Description, decoherence and the Prigogine effect
The application cites an experimental precedent for the non-equilibrium route: Mitrano and colleagues in Nature in February 2016, who reported a large increase in carrier mobility and the opening of a gap in the optical conductivity when metallic potassium-doped fullerene was excited with mid-infrared optical pulses.Description, closing paragraphs, citation of Nature 530, 461
The way in
https://patents.google.com/patent/US20190058105A1/enHow to cite it
Salvatore Cezar Pais, US Department of the Navy (2019) Piezoelectricity-induced Room Temperature Superconductor US20190058105A1