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US4581159A Expired / Lapsed US ⏱️ 0.0 years remaining

Voltage-dependent resistor and method of manufacturing same

Assignee: US Philips Corp
•
Filing: 1982-05-28
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Granted: 1986-04-08
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Expires: 2002-05-28
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Abstract

Abstract A voltage-dependent resistor having a low operational field strength with a ceramic sintered body on the basis of a polycrystalline alkaline earth metal titanate doped with a small quantity of a metal oxide so as to produce an N-type conductivity, in which the sintered body comprises at its grain boundaries insulating layers formed by in-diffusion of at least a metal oxide or at least a metal oxide compound and comprises of an alkaline earth metal titanate having Perowskite structure of the general formula: (A.sub.1-x Ln.sub.x)TiO.sub.3.yTiO.sub.2 or A(Ti.sub.1-x Me x )O 3 .yTiO 2 wherein: A=alkaline earth metal; Ln=rare earth metal; Me=metal having a valency of 5 or more; 0.0005<x<solubility limit in the Perowskite phase; y=0.001 to 0.02. The insulating layers are formed in that the sintered body is covered on its surface with a suspension containing at least a metal oxide having a comparatively low melting-point as compared with the sintered body or at least a metal oxide compound having a comparatively low melting-point with respect to the sintered body and is tempered in an oxidizing atmosphere at a temperature which is above the melting-point of the suspension component(s).

Inventors

  • 👤 Detlev Hennings
  • 👤 Axel Schnell
  • 👤 Herbert Schreinemacher

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-08 21:51
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/10; H01C7/105; H01C7/108; H01C7/115

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 167 words
A voltage-dependent resistor having a ceramic sintered body consisting of a polycrystalline alkaline metal titanate doped to N-type conductance with a metal oxide and which body is provided with electrodes on opposite located services thereof characterized in that said body has a Perowskite structure, consists of a strontium titanate containing excess TiO 2 which titanate has a formula selected from the group consisting of (Sr 1-x Ln x )TiO 3 .YTiO 2 and Sr(Ti 1-x )Me x )O 3 .YTiO 2 wherein Ln is a rare earth metal, Me is a metal having a valence of at least 5, 0.0005<x<solubility limit of the Ln in the crystal Perowskite phase and Y equals 0.001 to 0.02 and the sintered body is provided on its grain boundaries with insulating layers produced by diffusion into the surface layers of said grains by a metal oxide or a metal oxide compound, each of said metal oxide and said metal oxide compound having a melting point below that of said sintered body.
Claim 2
Dependent Claim 167 words
A voltage-dependent resistor having a ceramic sintered body consisting of a polycrystalline alkaline metal titanate doped to N-type conductance with a metal oxide and which body is provided with electrodes on opposite located services thereof characterized in that said body has a Perowskite structure, consists of a strontium titanate containing excess TiO 2 which titanate has a formula selected from the group consisting of (Sr 1-x Ln x )TiO 3 .YTiO 2 and Sr(Ti 1-x )Me x )O 3 .YTiO 2 wherein Ln is a rare earth metal, Me is a metal having a valence of at least 5, 0.0005<x<solubility limit of the Ln in the crystal Perowskite phase and Y equals 0.001 to 0.02 and the sintered body is provided on its grain boundaries with insulating layers produced by diffusion into the surface layers of said grains by a metal oxide or a metal oxide compound, each of said metal oxide and said metal oxide compound having a melting point below that of said sintered body.
Claim 3
Dependent Claim 17 words
A voltage-dependent resistor as claimed in claim 1, characterized in that strontium is the alkaline earth metal.
Claim 4
Dependent Claim 17 words
A voltage-dependent resistor as claimed in claim 1, characterized in that lanthanum is the rare earth metal.
Claim 5
Dependent Claim 19 words
A voltage-dependent resistor as claimed in claim 1, characterized in that Niobium is the metal having the valency 5.
Claim 6
Dependent Claim 18 words
A voltage-dependent resistor as claimed in claim 1, characterized in that tungsten is the metal having the valency>5.
Claim 7
Dependent Claim 65 words
A voltage-dependent resistor as claimed in claim 1, characterized in that the insulating layers are formed from at least a metal oxide or at least a metal oxide compound which has a lower melting point than the Perowskite phase, which readily wets the polycrystalline Perowskite phase on its grain boundaries and which shows reversible breakdown phenomena at field strengths occurring during operation of the component.
Claim 8
Dependent Claim 20 words
A voltage-dependent resistor as claimed in claim 6, characterized in that Bi 2 O 3 is the diffusing metal oxide.
Claim 9
Dependent Claim 25 words
A voltage-dependent resistor as claimed in claim 6, characterized in that lead germanate Pb 5 Ge 3 O 11 is the diffusing metal oxide compound.

References Cited (Backward Citations)

EP0044981A2 Cited
US4347167A Cited
US4438214A Cited
US4405477A Cited
US4436650A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1989-04-07 1989-10-07 1990-04-08 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1993-04-07 1993-10-07 1994-04-08 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1997-04-07 1997-10-07 1998-04-08 $7700.00 Window Closed / Lapsed

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