Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/26—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on ferrites
  • C04B35/2608—Compositions containing one or more ferrites of the group comprising manganese, zinc, nickel, copper or cobalt and one or more ferrites of the group comprising rare earth metals, alkali metals, alkaline earth metals or lead
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/26—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on ferrites
  • C04B35/2608—Compositions containing one or more ferrites of the group comprising manganese, zinc, nickel, copper or cobalt and one or more ferrites of the group comprising rare earth metals, alkali metals, alkaline earth metals or lead
  • C04B35/2616—Compositions containing one or more ferrites of the group comprising manganese, zinc, nickel, copper or cobalt and one or more ferrites of the group comprising rare earth metals, alkali metals, alkaline earth metals or lead containing lithium
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01C—RESISTORS
  • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01C—RESISTORS
  • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
  • H01C7/001—Mass resistors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01C—RESISTORS
  • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
  • H01C7/04—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having negative temperature coefficient
  • H01C7/042—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having negative temperature coefficient mainly consisting of inorganic non-metallic substances
  • H01C7/043—Oxides or oxidic compounds
  • H01C7/045—Perovskites, e.g. titanates

Definitions

• the invention relates to a sintered, electrical resistor substantially consisting of a phase of oxidic compounds with perovskite structure, containing Fe and/or Cr or else Co and Fe and/or Cr, in which at least one of the metals Fe, Cr and Co occurs in the trivalent and the tetravalent form.
• a sintered, electrical resistor substantially consisting of a phase of oxidic compounds with perovskite structure, containing Fe and/or Cr or else Co and Fe and/or Cr, in which at least one of the metals Fe, Cr and Co occurs in the trivalent and the tetravalent form.
• manganese in the tetravalent form may be included.
• it is desirable to restrict the Co content in the conductive phase to not more than 90 atom percent, calculated on the total content of Fe, Cr, Co and Mn.
• Part of the said metal ions may furthermore be replaced by other small trivalent or tetravalent metal ions, for example of Al, Ti and Ni.
• other small trivalent or tetravalent metal ions for example of Al, Ti and Ni.
• ABO The general formula for the chemical composition of perovskites is ABO wherein A designates a large metal ion, having an ion radius according to Goldschmidt of more than 1.0 A. and B a small metal ion having an ion radius between 0.5 and 1.0 A., the sum of the valencies of A and B being 6. Both A and B may designate a mixture of metal ions which fulfil the afore said conditions.
• a mixed crystal of LaFe +O with SrFe +O inay for example, be formed by sintering in air La O SrO (if desired in the form of carbonate) and Fe O at temperatures lying between 1250" C. and 1400 C.
• La O SrO if desired in the form of carbonate
• Fe O at temperatures lying between 1250" C. and 1400 C.
• the desired concentrations of Fe and Fe are obtained by a choice of the ratio between La and Sr.
• the ratio between the concentrations of the trivalent and the tetravalent small metal ions may be adjusted fairly accurately in accordance with the formula ABO; by means of the concentrations of the trivalent and the bivalent large metal ions, if the latter ratio exceeds about 1.5.
• oxygen content may be acted upon to some extent by means of the partial 'oxygen pressure of the gaseous atmosphere in which the sintering takes place.
• the deviation from the 1 formula ABO may be considerable.
• strontium ferrite sintered in air at 1320 C. the composition SrFeO has been found. Since the effect of the partial oxygen pressure is comparatively slight, stable resisters are also obtained with the perovskites having an oxygen deficiency.
• perovskite compositions containing Fe or Cr exhibit a high temperature coefficient at a comparatively low specific resistance.
• a greater variety in resistance properties may be obtained by combining the Feand Cr-containing perovskites with one another or with the other aforesaid metals.
• the sintered products according to the invention should be constituted mainly by the aforesaid conductive phases. Moreover, other conductive or nonconductive phases may be contained in the sintered products to a content of about 15% by volume. If desired, fluxes, for example copper oxide, zinc oxide, clay and glass may be added to a quantity of about 10% by weight.
• the products according to the invention may be obtained from the composing oxides, if desired in the form of double oxides or compounds, for example carbonates, changing into oxides during sintering.
• the said constituents are ground, mixed, worked up to obtain a paste, for example with an organic binder, and then, subsequent to shaping, sintered in an oxygen containing atmosphere.
• the constituents may, as an alternative, be caused to react, subsequent to mixing, at a higher temperature: they may then be ground again and sintered subsequent to shaping.
• a sintered electrical resistor having a conductive phase consisting of crystals having a perovskite structure and a composition corresponding approximately to the formula AB D ,,O wherein A represents a mixture of at least one trivalent metal ion selected from the group consisting of La+++, Nd and Pr+++ and at least one bivalent metal ion selected from the group consisting of Ca++, Sr++, Ba++ and Pb++; B represents at least one trivalent metal ion selected from the group consisting of Fe+++, Cr+++, and Co+++, D represents at least one tetravalent metal ion selected from the group consisting of Fe++++ cr++++ Co++++ and Mn++++; Mn++++ Co+++ and Co++++ being present only when at least one of the other metal ions other than the metal ions represented by A in said formula is present, the elements Co, Fe and Cr being present in both the trivalent and tetravalent states, and wherein n represents a numeral having a value greater than
• the resistor of claim 1 in which the conductive phase contains Co in an amount up to atom percent of the total content of Fe, Cr, Co and Mn.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Compositions Of Oxide Ceramics (AREA)
• Conductive Materials (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=31885036

Family Applications (1)

Country Status (5)

Cited By (6)

Families Citing this family (9)

Family Cites Families (1)

• 1954
  • 1954-06-26 NL NL95807D patent/NL95807C/xx active
• 1955
  • 1955-06-22 DE DEN10826A patent/DE1042080B/de active Pending
  • 1955-06-23 GB GB18200/55A patent/GB791167A/en not_active Expired
  • 1955-06-24 BE BE539287D patent/BE539287A/xx unknown
  • 1955-06-27 US US518388A patent/US2862891A/en not_active Expired - Lifetime

Non-Patent Citations (1)

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