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Cabinet/The bismuth battery

Research article / 1 minute read

Hall Effect

The Hall effect is the appearance of a transverse potential difference across a current-carrying conductor placed in a magnetic field perpendicular to the current. Charge carriers are deflected sideways by the Lorentz force, producing a voltage across the width of the conductor.

Formulation as used in the source

Palmer H. Craig's 1926 Physical Review paper defines the Hall coefficient as

R = Ed / IH

where R is the Hall coefficient, d the film thickness in cm, I the longitudinal current in abamperes, H the field in gausses, and E the net Hall emf. The patent US1822129 — System & Apparatus Employing the Hall Effect gives the equivalent relation

E = HI/d

Why bismuth

Bismuth is a semimetal with a long carrier mean free path and large magnetoresistance, properties documented in the later bismuth-film literature appended to the source. Craig's 1926 paper selected bismuth and tellurium because they have the highest Hall coefficient of the ordinary metals. The source's appended bibliography documents decades of later work on bismuth films — quantum size effects, epitaxial growth, magnetotransport, nanowire quantum confinement — none of which tests Craig's device.

Related phenomena

The patent names the Corbino Effect — radial current in a disc under a perpendicular field producing a circular current — as a related phenomenon.

See also

Hall-Effect Rectification, Anomalous Low-Field Hall Coefficient in Bismuth, Additive Principle (Series Hall Potentials).

Further reading: Camargo and Colleagues, 2021: A Ferromagnetic-Like Anomalous Hall Signal in Bismuth Crystals Below 30 mT covers a modern report of an anomalous (hysteretic) Hall signal in bismuth crystals at low fields and liquid-helium temperatures.

Source notes & attribution

https://rexresearch.com/craig/craig.htm

Linked from.

Articles that refer to this reading

Camargo and Colleagues, 2021: A Ferromagnetic-Like Anomalous Hall Signal in Bismuth Crystals Below 30 mT

Palmer Craig's 1926 claim, covered in Anomalous Low-Field Hall Coefficient in Bismuth , was that bismuth's Hall coefficient does something unexpected when the magnetic field becomes very weak. C. W. Heaps disputed it the following year. Nearly a century later, a group at the Institute of Physics of the Polish Academy of Sciences

Anomalous Low-Field Hall Coefficient in Bismuth

The anomalous low-field Hall coefficient is Palmer H. Craig 's 1926 claim that the Hall coefficient of thin bismuth films rises sharply as the magnetic field falls below about 0.3 gauss. It is the central physical claim of the dossier and the one directly contradicted by C. W. Heaps in 1927.

Corbino Effect

The Corbino effect is the appearance of a circular current in a conducting disc when a radial current flows through it in the presence of a perpendicular magnetic field. It is named in US1822129 — System & Apparatus Employing the Hall Effect , Palmer H. Craig 's Hall-effect patent, as a related phenomenon to the Hall effect.

Hall-Effect Rectification

Hall-effect rectification is the proposal that the synchronous reversal of Hall polarity with an alternating magnetic field or alternating current can be used to convert AC into pulsating DC. It is the operating principle claimed for Palmer H. Craig 's device and patented in US1822129 — System & Apparatus Employing the Hall Effe

Thin Bismuth Film Preparation

Thin bismuth films are the material at the center of the Craig dossier. The source describes preparation methods from the 1920s and, in its appended bibliography, from later mainstream research.

Palmer H. Craig

Palmer H. Craig was an American physicist, head of the physics department at Mercer University in Macon, Georgia, and the claimant behind a 1920s bismuth-based "Hall Effect Device" promoted as a replacement for vacuum tubes and batteries in radio receivers.