EP0637292A1 - Sintered-ceramic material for high-stability thermistors, and a method of producing the material - Google Patents

Sintered-ceramic material for high-stability thermistors, and a method of producing the material

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Publication number
EP0637292A1
EP0637292A1 EP93908815A EP93908815A EP0637292A1 EP 0637292 A1 EP0637292 A1 EP 0637292A1 EP 93908815 A EP93908815 A EP 93908815A EP 93908815 A EP93908815 A EP 93908815A EP 0637292 A1 EP0637292 A1 EP 0637292A1
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EP
European Patent Office
Prior art keywords
thermistors
sintered ceramic
producing
nimn
manganese
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EP93908815A
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German (de)
French (fr)
Inventor
Adalbert Prof. Dr. Feltz
Hans Georg Dr. Schuster
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TDK Electronics AG
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Siemens Matsushita Components GmbH and Co KG
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Publication of EP0637292A1 publication Critical patent/EP0637292A1/en
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    • 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
    • C04B35/016—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 manganites
    • 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

Definitions

  • the present invention relates to a sintered ceramic for highly stable thermistors according to the preamble of patent claim 1 and to a method for producing such a sintered ceramic according to the preamble of patent claim 2.
  • GB-PS 1 226 789 technical solutions known from GB-PS 1 226 789 are based on semiconducting oxides of the transition elements and their combinations, for example in spinels.
  • Multi-phase systems for example cobalt-manganese oxide systems, which are modified by further components such as copper oxide, nickel oxide or lithium oxide (see, for example, US Pat. No. 3,219,480), are often used without striving for the advantage of forming a uniform phase.
  • This procedure generally involves a considerable spread of the data of the individual copies and in particular from batch to batch, since the electrical characteristics of the thermistor Depending on the structure structure of the ceramic, the parameters assume different values. In such heterogeneous systems, the equilibrium composition of the phases is generally temperature-dependent, which has negative effects on the temporal stability of the electrical parameters.
  • thermistors are manufactured, for example, on the basis of the Ni Mn 3 0 system.
  • the range of the composition 0 ⁇ x ⁇ 1.275 there is a largely uniform phase, which no longer has the disadvantages mentioned of a large spread, provided that the oxidative decomposition in air at temperatures below 720 ° C. in ⁇ -Mn 2 O 3 at the management of the sintering process for thermistor production is avoided by cooling sufficiently quickly, and the application range is limited to a maximum of 150 to 200 ° C.
  • Ni x Mn 3-x O 4 in which stepwise substitution of manganese by zinc is carried out in accordance with the general formula Zn NiMn 2-z O 4 .
  • the spinel compounds Zn 1/3 NiMn 5/3 O 4 prove to be completely stable in the cooling process at any heating rate.
  • the spinels containing the two Zn with a B constant of approximately 3800 K achieve a thermistor characteristic comparable to NiMn 2 O 4 .
  • a disadvantage is that the temperature of the elimination of oxygen in the
  • the invention has for its object to provide a sintered ceramic with a large B constant with high uniformity and phase stability as well as a method for their production in order to be able to manufacture thermistors with high stability and sensitivity for a temperature range up to 650 ° C on such a basis.
  • the task is with a sintered ceramic as well as a
  • Figure 1 is a diagram of the decomposition and regression of
  • Figure 2 is a diagram of the specific conductivity as
  • the essence of the invention is to prevent the decomposition into different oxide phases with oxygen uptake when the temperature falls below a certain temperature by incorporating suitable cations in a nickel-manganese oxide spinel system, and at the same time to set conductivity values and a high B constant in order to in a temperature range up to 650 oC to determine temperatures sensitive by resistance measurements.
  • MgO, nickel carbonate and manganese carbonate are dissolved in dilute acid, preferably in acetic acid, and with addition of oxalic acid in a slight excess and evaporation, mixed crystals of MgNiMn (C 2 O 4 ) 3 . 6 H 2 O are obtained, the decomposition of which gives a spinel powder with homogeneous cation distribution and high sintering activity by gradual heating in air to 440 ° C.
  • the mixture is heated to 650 ° C., then compression molded into tablets and the sintering is carried out by heating to 1000 ° C. in air. It will be one Density of 70 to 80% reached. A decay into NiO and the spinel takes place with elimination of oxygen
  • FIG. 1 shows the course of the decomposition and the regression of MgNiMnO 4 at a heating and cooling rate of 1 K / min in air.
  • FIG. 2 shows the course of the specific conductivity as a function of the reciprocal temperature T in a semi-logarithmic representation.
  • the thermistor characteristic can heat up and down in the entire temperature range between room temperature and 650 oC without detectable drift of the characteristic values are traversed.

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

Abstract

The invention concerns a sintered-ceramic material, for high-stability thermistors, of the general formula: MgzNiMn2-zO4, where 0 < z < 1, produced by converting a thermally unstable nickel manganese oxide spinel system, such as NiMn2O4, into a thermodynamically stable compound of the composition MgNiMnO4 by the substitution of manganese by magnesium.

Description

Sinterkeramik für hochstabile Thermistoren und Verfahren zu ihrer Herstellung Sintered ceramics for highly stable thermistors and processes for their manufacture
Die vorliegende Erfindung betrifft eine Sinterkeramik für hochstabile Thermistoren nach dem Oberbegriff des Patentanspruchs 1 sowie ein Verfahren zur Herstellung einer derartigen Sinterkeramik nach dem Oberbegriff des Patentanspruchs 2. The present invention relates to a sintered ceramic for highly stable thermistors according to the preamble of patent claim 1 and to a method for producing such a sintered ceramic according to the preamble of patent claim 2.
Beispielsweise aus der GB-PS 1 226 789 bekannte technische Lösungen gehen von halbleitenden Oxiden der Übergangselemente und deren Kombinationen z.B. in Spinellen aus. Dabei gelangen vielfach Mehrphasensysteme, z.B. Kobalt-Manganoxid-Systeme zur Anwendung, die durch weitere Komponenten wie Kupferoxid, Nickeloxid oder Lithiumoxid (siehe z.B. US-PS 3 219 480) modifiziert werden, ohne daß der Vorteil der Bildung einer einheitlichen Phase angestrebt wird. Der Nennwiderstand R25 eines Thermistors, d.h. der elektrische Widerstand bei der Temperatur T = 25 °C und die für die Empfindlichkeit der Temperaturmessung maßgebliche Materialkonstante B eines Thermistors gemäß der Beziehung For example, technical solutions known from GB-PS 1 226 789 are based on semiconducting oxides of the transition elements and their combinations, for example in spinels. Multi-phase systems, for example cobalt-manganese oxide systems, which are modified by further components such as copper oxide, nickel oxide or lithium oxide (see, for example, US Pat. No. 3,219,480), are often used without striving for the advantage of forming a uniform phase. The nominal resistance R 25 of a thermistor, ie the electrical resistance at the temperature T = 25 ° C. and the material constant B of a thermistor relevant for the sensitivity of the temperature measurement according to the relationship
R(T) = Roexp(B/T) = R25exp(l/T-1/298) wird auf der Basis derartiger mehrphasiger Systeme durch eine entsprechende Reaktionsführung im Sinterprozeß auf variable Werte eingestellt, so daß bei einem gegebenen Versatz die Produktion eines bestimmten Sortiments von Thermistoren möglich ist. Diese Verfahrensweise schließt im allgemeinen eine beträchtliche Streubreite der Daten der Einzelexemplare und insbesondere von Charge zu Charge ein, da die den Thermistor kennzeichnenden elektrischen Parameter je nach dem erreichten Strukturgefüge der Keramik verschiedene Werte annehmen. In derartigen heterogenen Systemen ist die Gleichgewichtszusammensetzung der Phasen im allgemeinen temperaturabhängig, woraus sich negative Wirkungen auf die zeitliche Stabilität der elektrischen Parameter ergeben. R (T) = R o exp (B / T) = R 25 exp (l / T-1/298) is set to variable values on the basis of such multiphase systems by a corresponding reaction procedure in the sintering process, so that with a given offset the production of a certain range of thermistors is possible. This procedure generally involves a considerable spread of the data of the individual copies and in particular from batch to batch, since the electrical characteristics of the thermistor Depending on the structure structure of the ceramic, the parameters assume different values. In such heterogeneous systems, the equilibrium composition of the phases is generally temperature-dependent, which has negative effects on the temporal stability of the electrical parameters.
Aus der Siemens-Zeitschrift 47, Januar 1973, Heft 1, Seiten 65 bis 67 ist es bekannt geworden, daß Thermistoren, z.B. auf der Basis des Systems Ni Mn3 0. gefertigt werden. Für den Bereich der Zusammensetzung 0 < x < 1,275 ergibt sich eine weitgehend einheitliche Phase, die die genannten Nachteile einer großen Streubreite nicht mehr aufweist, vorausgesetzt, daß der bei Temperaturen unterhalb 720 ºC an Luft eintretende oxidative Zerfall in α -Mn2O3 bei der Führung des Sinterprozesses zur Thermistorfertigung durch hinreichend rasches Abkühlen vermieden, und der Anwendungsbereich auf maximal 150 bis 200 ºC begrenzt wird. From Siemens magazine 47, January 1973, number 1, pages 65 to 67, it has become known that thermistors are manufactured, for example, on the basis of the Ni Mn 3 0 system. For the range of the composition 0 <x <1.275 there is a largely uniform phase, which no longer has the disadvantages mentioned of a large spread, provided that the oxidative decomposition in air at temperatures below 720 ° C. in α-Mn 2 O 3 at the management of the sintering process for thermistor production is avoided by cooling sufficiently quickly, and the application range is limited to a maximum of 150 to 200 ° C.
Es ist gezeigt worden, daß der Nachteil des Zerfalls in ein heterogenes. Stoffsystem unter Sauerstoffaufnahme im Bereich niedriger Temperatur in Spinellverbindungen It has been shown that the disadvantage of decaying into a heterogeneous. Material system with oxygen uptake in the low temperature range in spinel compounds
NixMn3-xO4, in denen entsprechend der allgemeinen Formel Zn NiMn2-z O4 eine schrittweise Substitution von Mangan durch Zink vorgenommen wird, ausgeschlossen werden kann. Die Spinellverbindungen Zn1/3NiMn5/3O4 erweisen sich im Abkühlprozeß bei beliebiger Abheizrate als völlig stabil. Dabei wird das bei den beiden Zn enthaltenden Spinellen mit einer B-Konstanten von etwa 3800 K eine mit NiMn2O4 vergleichbare Thermistorkennlinie erreicht. Ein Nachteil ist, daß die Temperatur der Sauerstoffabspaltung im Ni x Mn 3-x O 4 , in which stepwise substitution of manganese by zinc is carried out in accordance with the general formula Zn NiMn 2-z O 4 . The spinel compounds Zn 1/3 NiMn 5/3 O 4 prove to be completely stable in the cooling process at any heating rate. In this case, the spinels containing the two Zn with a B constant of approximately 3800 K achieve a thermistor characteristic comparable to NiMn 2 O 4 . A disadvantage is that the temperature of the elimination of oxygen in the
Bereich hoher Temperatur von 950 ºC für NiMn2O4 an Luft mit der Ausscheidung einer NiO-Phase verbunden ist, für Zn1/3NiMn5/3O4 und Zn2/3NiMn4/3O4 auf 800 ºC herabgemin dert wird. Um eine hinreichende Sinterverdichtung zu erreichen, muß die Prozeßführung daher die obere Stabilitätsgrenze überschreiten und ein heterogenes Stadium durchlaufen, d.h. erst durch eine in der Regel zeitaufwendige Rückoxydation bei Temperaturen < 800 ºC wird unter Vereinigung der Phasen eine homogene Keramik erhalten. High temperature range of 950 ° C for NiMn 2 O 4 in air associated with the precipitation of a NiO phase, for Zn 1/3 NiMn 5/3 O 4 and Zn 2/3 NiMn 4/3 O 4 reduced to 800 ° C is changed. In order to achieve sufficient sinter densification, the process control must therefore exceed the upper stability limit and pass through a heterogeneous stage, ie a homogeneous ceramic is obtained only through a generally time-consuming reoxidation at temperatures <800 ºC by combining the phases.
Für Zn0.1Fe0.9NiMnO4 ist nachgewiesen worden, daß auf der Basis des Spinellsystems ZnzFe1-zNiMnO4 bei Erhalt der Phasenstabilität der Nachteil einer notwendigen Sinterung im Zersetzungsbereich weitgehend vermieden werden kann. Bei der Spinellzusammensetzung Zn0,1Fe0,9NiMnO4 liegt die Zersetzungstemperatur bei 950 ºC und damit in einem mit NiMn2O4 vergleichbaren Bereich. Die B-Konstante ist mit 3275 K gegenüber NiMn2O4 geringer. For Zn 0.1 Fe 0.9 NiMnO 4 it has been shown that the disadvantage of a necessary sintering in the decomposition area can be largely avoided on the basis of the spinel system Zn z Fe 1-z NiMnO 4 while maintaining the phase stability. With the spinel composition Zn 0.1 Fe 0.9 NiMnO 4 , the decomposition temperature is 950 ° C and thus in a range comparable to NiMn 2 O 4 . The B constant is 3275 K lower than NiMn 2 O 4 .
Der Erfindung liegt die Aufgabe zugrunde, eine Sinterkeramik mit großer B-Konstante bei zugleich hoher Einheitlichkeit und Phasenstabilität sowie ein Verfahren zu deren Herstellung anzugeben, um auf einer solchen Basis Thermistoren hoher Stabilität und Empfindlichkeit für einen Temperaturbereich bis 650 ºC herstellen zu können. The invention has for its object to provide a sintered ceramic with a large B constant with high uniformity and phase stability as well as a method for their production in order to be able to manufacture thermistors with high stability and sensitivity for a temperature range up to 650 ° C on such a basis.
Die Aufgabe wird bei einer Sinterkeramik sowie einem The task is with a sintered ceramic as well as a
Verfahren der eingangs genannten Art erfindungsgemäß durch die Merkmale des kennzeichnenden Teils des Patentanspruchs 1 bzw. 2 gelöst. Method of the type mentioned in the invention solved by the features of the characterizing part of patent claim 1 or 2.
Die Erfindung wird im folgenden anhand von Ausführungsbeispielen in Verbindung mit den Figuren der Zeichnung näher erläutert. Es zeigt: The invention is explained in more detail below on the basis of exemplary embodiments in conjunction with the figures of the drawing. It shows:
Figur 1 ein Diagramm der Zersetzung und Rückbildung von  Figure 1 is a diagram of the decomposition and regression of
MgNiMnO4 als Funktion der Zeit, undMgNiMnO 4 as a function of time, and
Figur 2 ein Diagramm der spezifischen Leitfähigkeit als Figure 2 is a diagram of the specific conductivity as
Funktion der Zeit. Der Kern der Erfindung besteht darin, durch den Einbau geeigneter Kationen in ein Nickel-Manganoxid-Spinellsystem den Zerfall in verschiedene Oxidphasen unter Sauerstoffaufnahme bei Unterschreiten einer bestimmten Temperatur zu unterbinden und dabei zugleich Leitfähigkeitswerte und eine hohe B-Konstante einzustellen, um in einem Temperaturbereich bis 650 ºC Temperaturen durch Widerstandsmessungen empfindlich zu bestimmen. In Spinellverbindungen des Systems NixMn3-xO4, z.B. in der Reihe Mg2NiMn2-zO4 (x = 1, 0 < z < 1) wird durch Substitution von Mangan durch Magnesium schrittweise eine Verbesserung der thermischen Stabilität mit zunehmendem Magnesiumgehalt erreicht. MgNiMnO4 (z = 1) erweist sich im gesamten Temperaturbereich bis zu seiner oberen Zersetzungstemperatur von 720 ºC als ein stabiler Spinell. Function of time. The essence of the invention is to prevent the decomposition into different oxide phases with oxygen uptake when the temperature falls below a certain temperature by incorporating suitable cations in a nickel-manganese oxide spinel system, and at the same time to set conductivity values and a high B constant in order to in a temperature range up to 650 ºC to determine temperatures sensitive by resistance measurements. In spinel compounds of the Ni x Mn 3-x O 4 system , for example in the series Mg 2 NiMn 2-z O 4 (x = 1, 0 <z <1), the manganese is gradually replaced by magnesium to improve the thermal stability increasing magnesium content reached. MgNiMnO 4 (z = 1) proves to be a stable spinel in the entire temperature range up to its upper decomposition temperature of 720 ° C.
Weiterhin ist erfindungsgemäß vorgesehen, daß MgO, Nickelcarbonat und Mangancarbonat in verdünnter Säure, vorzugsweise in Essigsäure gelöst und unter Zusetzen von Oxalsäure im geringen Überschuß und Eindampfen Mischkristalle MgNiMn (C2O4)3 . 6 H2O erhalten wexden, deren Zersetzung durch stufenweises Erhitzen an Luft bis auf 440 ºC ein Spinellpulver mit homogener Kationenverteilung und hoher Sinteraktivität liefert. It is further provided according to the invention that MgO, nickel carbonate and manganese carbonate are dissolved in dilute acid, preferably in acetic acid, and with addition of oxalic acid in a slight excess and evaporation, mixed crystals of MgNiMn (C 2 O 4 ) 3 . 6 H 2 O are obtained, the decomposition of which gives a spinel powder with homogeneous cation distribution and high sintering activity by gradual heating in air to 440 ° C.
MgNiMn(C2O4)3 · 6 H2O + ½ O2 ┄> MgNiMn (C 2 O 4 ) 3 · 6 H 2 O + ½ O 2 ┄>
MgNiMnO4 +3 CO2 + 3 CO + 6 H2O MgNiMnO 4 +3 CO 2 + 3 CO + 6 H 2 O
Zwecks Einstellung einer für die granulometrische Aufbereitung günstigen spezifischen Oberfläche von etwa 1 m2/g erhitzt man auf 650 ºC, nimmt anschließend die Preßformgebung zu Tabletten vor und führt die Sinterverdichtung durch Erhitzen auf 1000 ºC an Luft aus. Es wird eine Dichte von 70 bis 80 % erreicht. Dabei läuft unter Sauerstoffabspaltung ein Zerfall in NiO und den SpinellIn order to set a specific surface area of approximately 1 m 2 / g, which is favorable for the granulometric preparation, the mixture is heated to 650 ° C., then compression molded into tablets and the sintering is carried out by heating to 1000 ° C. in air. It will be one Density of 70 to 80% reached. A decay into NiO and the spinel takes place with elimination of oxygen
ab, der bei der anscnließenden Temperung bei 650 ºC aufgrund der vorhandenen Porosität unter Sauerstoffaufnahme vollständig rückläufig ist. which, in the subsequent tempering at 650 ° C., is completely reduced due to the porosity present with the absorption of oxygen.
Figur 1 zeigt den Verlauf der Zersetzung und die R'ückbildüng von MgNiMnO4 bei einer Aufheiz- und Abkühlgeschwindigkeit von 1 K/min an Luft. FIG. 1 shows the course of the decomposition and the regression of MgNiMnO 4 at a heating and cooling rate of 1 K / min in air.
Die Erfindung wird an folgendem Ausführungsbeispiel näher erläutert: The invention is explained in more detail using the following exemplary embodiment:
Durch Lösen von Magnesiumoxid, Nickelkarbonat und Mangankarbonat in Essigsäure, anschließende Zugabe von Oxalsäure in geringem Überschuß, um eine zuverlässige Reduzierung restlichen MnIII zu MnII zu gewährleisten, sowie nachfolgendes Eindampfen werden Oxalatmischkristalle der Zusammensetzung MgNiMn(C2O4)3 · 6 H2O Orhalten. Durch stufenweises Erhitzen auf 650 ºC unter Sauerstoff wird eine einheitliche Spinellphase zugänglich, die als sinteraktives Pulver anfällt. Formgebung zu Tabletten durch Pressen sowie Sintern bei 900 ºC bis 1000 ºC in einer Sauerstoffatmosphäre für 6 Stunden und Rückoxydation durch Halten bei 650 ºC liefert die erfindungsgemäße Sinterkeramik einheitlicher Spinellphase. Man kontaktiert mit einer Ag-Paste, brennt bei 650 ºC ein und hält längere Zeit zwecks Formierung auf der angegebenen Temperatur. By dissolving magnesium oxide, nickel carbonate and manganese carbonate in acetic acid, then adding a small excess of oxalic acid to ensure a reliable reduction of the remaining Mn III to Mn II , and subsequent evaporation, oxalate mixed crystals with the composition MgNiMn (C 2 O 4 ) 3 · 6 H 2 O Oralten. By gradually heating to 650 ºC under oxygen, a uniform spinel phase is obtained, which is obtained as a sinter-active powder. Shaping into tablets by pressing and sintering at 900 ° C to 1000 ° C in an oxygen atmosphere for 6 hours and re-oxidation by holding at 650 ° C, the sintered ceramic according to the invention provides a uniform spinel phase. Contact is made with an Ag paste, baked at 650 ° C. and held at the specified temperature for a long time for the purpose of formation.
Figur 2 zeigt den Verlauf der spezifischen Leitfähigkeit in Abhängigkeit von der reziproken Temperatur T in einer halblogarithmischen Darstellung. Die Thermistorkennlinie kann im gesamten Temperaturbereich zwischen Raumtemperatur und 650 ºC auf- und abheizend ohne nachweisbare Drift der Kennwerte durchfahren werden. FIG. 2 shows the course of the specific conductivity as a function of the reciprocal temperature T in a semi-logarithmic representation. The thermistor characteristic can heat up and down in the entire temperature range between room temperature and 650 ºC without detectable drift of the characteristic values are traversed.
Die Eigenschaften von MgNiMnO4-Thermistorproben sind in der nachfolgenden Tabelle angegeben. The properties of MgNiMnO 4 thermistor samples are given in the table below.
Tabelle table
Eigenschaften von MgNiMnO4-Thermistorproben Zusammensetzung MgNiMnO4 Properties of MgNiMnO 4 thermistor samples Composition MgNiMnO 4
Dichte 70 - 80 % Density 70 - 80%
Anzahl der Proben 10 Number of samples 10
Zersetzungstemperatur Decomposition temperature
(PO₂ = 0.21º105 Pa) (P O₂ = 0.21º10 5 Pa)
- obere (O2-Abspaltung) 720 ºC - Upper (O 2 elimination) 720 ° C
- untere (O2-Auf nähme ) stabil - Lower (O 2 recording) stable
20 ºC 4 · 10-7Ω-1cm-1 200 ºC 1.5 · 10-4Ω-1cm-1 400 ºC 2.6 · 10-3Ω-1cm-1 600 ºC 1.2 · 10-2Ω-1cm-1 20 ºC 4 · 10 -7 Ω -1 cm -1 200 ºC 1.5 · 10 -4 Ω -1 cm -1 400 ºC 2.6 · 10 -3 Ω -1 cm -1 600 ºC 1.2 · 10 -2 Ω -1 cm -1
B 4550 K ± 30 K B 4550 K ± 30 K.

Claims

Patentansprüche Claims
1. Sinterkeramik für hochstabile Thermistoren auf der Basis 1. Sintered ceramic for highly stable thermistors on the base
NixMn3-xO4 mit x > 0 Ni x Mn 3-x O 4 with x> 0
g e k e n n z e i c h n e t d u r c h marked by
die allgemeine Formel the general formula
MgzNiMn2-zO4 mit x = 1 und 0 < z < 1. Mg z NiMn 2-z O 4 with x = 1 and 0 <z <1.
2. Sinterkeramik nach Anspruch 1, 2. sintered ceramic according to claim 1,
d a d u r c h g e k e n n z e i c h n e t, characterized,
daß z = 1 ist. that z = 1.
3. Verfahren zur Herstellung einer Sinterkeramik für hochstabile Thermistoren nach Anspruch 1 und/oder 2, d a d u r c h g e k e n n z e i c h n e t , 3. A method for producing a sintered ceramic for highly stable thermistors according to claim 1 and / or 2, d a d u r c h g e k e n n e e c h n e t,
daß ein thermisch instabiles Stoffsystem einer NickelMangangoxid-Spinellphase wie NiMn2O4 durch Substitution von Mangan durch Magnesium in eine thermodynamisch stabile Verbindung der Zusammensetzung MgNiMnO4 überführt wird. that a thermally unstable material system of a nickel manganese oxide spinel phase such as NiMn 2 O 4 is converted into a thermodynamically stable compound of the composition MgNiMnO 4 by substitution of manganese with magnesium.
4. Verfahren zur Herstellung einer Sinterkeramik nach Anspruch 1 und/oder 2, 4. A method for producing a sintered ceramic according to claim 1 and / or 2,
d a d u r c h g e k e n n z e i c h n e t , characterized ,
daß durch Lösen eines Gemenges von MgO, Nickelkarbonat und Mangankarbonat in einem sauren Medium, Zusetzung von Oxalsäure und Eindampfen Oxalatmischkristalle der Zusammensetzung MgNiMn(C2O4)3 · 6 H2O hergestellt werden, deren Zersetzung durch stufenweises Erhitzen auf über 440 ºC zu einer einheitlichen Spinellphase führt, die als interaktives Pulver anfällt. that by dissolving a mixture of MgO, nickel carbonate and manganese carbonate in an acidic medium, adding oxalic acid and evaporating oxalate mixed crystals of the composition MgNiMn (C 2 O 4 ) 3 .6 H 2 O are produced, the decomposition of which is gradually increased to above 440 ° C. leads to a uniform spinel phase, which is obtained as an interactive powder.
5. Verfahren nach Anspruch 4, 5. The method according to claim 4,
d a d u r c h g e k e n n z e i c h n e t , characterized ,
daß als saures Medium Essigsäure verwendet wird. that acetic acid is used as the acidic medium.
6. Verfahren nach einem der Ansprüche 3 bis 5, 6. The method according to any one of claims 3 to 5,
d a d u r c h g e k e n n z e i c h n e t , characterized ,
daß durch Preßformgebung zu Tabletten und Sintern beithat by compression molding to tablets and sintering
Temperaturen um 1000 ºC zunächst ein heterogenes Gefüge hergestellt wird, das durch Tempern bei 650 ºC an Luft in eine einheitliche stabile Spinellphase überführt wird. At temperatures around 1000 ºC, a heterogeneous structure is first produced, which is converted into a uniform, stable spinel phase by annealing at 650 ºC in air.
EP93908815A 1992-04-24 1993-04-23 Sintered-ceramic material for high-stability thermistors, and a method of producing the material Withdrawn EP0637292A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4213631 1992-04-24
DE4213631 1992-04-24
PCT/DE1993/000360 WO1993022255A1 (en) 1992-04-24 1993-04-23 Sintered-ceramic material for high-stability thermistors, and a method of producing the material

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EP93908815A Withdrawn EP0637292A1 (en) 1992-04-24 1993-04-23 Sintered-ceramic material for high-stability thermistors, and a method of producing the material

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EP0638910B1 (en) * 1993-08-13 2002-11-20 Epcos Ag Sintered ceramic for stable high temperature-thermistors and their method of manufacture
DE19622112A1 (en) * 1996-06-01 1997-12-04 Philips Patentverwaltung Oxide ceramic thermistor containing indium
US7138901B2 (en) 2004-03-30 2006-11-21 General Electric Company Temperature measuring device and system and method incorporating the same
KR20100113321A (en) * 2009-04-13 2010-10-21 한국기계연구원 Highly dense and nano-grained spinel ntc thermistor thick films and preparation method thereof
CN108358633B (en) * 2018-05-24 2021-02-05 电子科技大学 Low-temperature sintered Ca5Mn4-xMgxV6O24Microwave dielectric material and preparation method thereof
CN112624740B (en) * 2020-12-26 2022-08-02 重庆材料研究院有限公司 High-entropy NTC thermistor ceramic material and preparation method thereof

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US3116254A (en) * 1961-05-29 1963-12-31 Gen Electric Method for making magnets
FR2582851B1 (en) * 1985-06-04 1988-07-08 Univ Toulouse COMPOSITIONS OF TRANSITION METAL MANGANITES IN THE FORM OF PARTICLES OR IN THE FORM OF CERAMICS, THEIR PREPARATION AND THEIR USE IN PARTICULAR IN THE MANUFACTURE OF THERMISTORS
DD295941A5 (en) * 1990-06-26 1991-11-14 Friedrich-Schiller-Universitaet,De METHOD FOR PRODUCING SINTER CERAMICS FOR THERMISTORS INCREASED SENSITIVITY AND STABILITY

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JPH07505857A (en) 1995-06-29

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