Negative temperature coefficient thermistors
AssigneeAT&T Bell Laboratories
InventorsDavid W. Johnson, Jr., Murray Robbins
Life of this patent
Estimating the term…
Abstract
Inexpensive Mn or Mg ferrites may be used as negative temperature coefficient thermistors. Fabrication of devices with the desired high temperature coefficients is facilitated by a processing method which forms a thin layer of oxidized and high resistivity material on a low resistivity layer of ferrite material.
Claims13
A thermistor comprising a first layer of material having the nominal atom composition M.sub.1-x Fe.sub.2+x-z R.sub.z O.sub.4, where M is at least one element selected from the group consisting of Mn and Mg, x is greater than or equal to 0.0 and less than or equal to 0.3, R is selected from the group consisting of Al and Ti, z is greater than or equal to 0.0 and less than or equal to 1.2, and electrical contacts on opposed surfaces of said layer, and a second and a third layer of material having the composition M.sub.1-x Fe.sub.2+x-z R.sub.z O.sub.4+.beta., said .beta. being greater than 0.0 and less than 0.2, said layers being disposed intermediate said first layer and said electrical contacts.
A thermistor comprising a first layer of material having the nominal atom composition M.sub.1-x Fe.sub.2+x-z R.sub.z O.sub.4, where M is at least one element selected from the group consisting of Mn, Mg, Ni, Co, Cu and Zn, x is greater than or equal to 0.0 and less than or equal to 0.3, R is selected from the group consisting of Al and Ti, z is greater than or equal to 0.0 and less than or equal to 1.2, electrical contacts to opposed surfaces of said layer, a second and a third layer of material having the composition M.sub.1-x Fe.sub.2+x-z R.sub.z O.sub.4+.beta., said .beta. being greater than 0.0 and less than 0.2, said layers being disposed intermediate said first layer and said electrical contacts.
Dependencies are inferred from the claim text.