Claims
- 1. A soft lithium-titanium-zinc ferrite having a resistivity of at least 10.sup.7 ohm-cm measured at 20.degree. C. and 100 volts, manufactured by forming a mixture of metal oxides and carbonates, crushing said formed mixture, calcining said crushed mixture in an air atmosphere at about 700.degree. C. for about 2 hours, and sintering said calcined mixture in an oxygen-containing atmosphere at from 950.degree. to 1100.degree. C. for from 1 to 18 hours; wherein said mixture consists essentially of metal oxides and carbonates in proportions calculated as oxides which satisfy the formula
- Li.sub.a Ti.sub.t Zn.sub.z Mn.sub.m Fe.sub.b O.sub.4 +.beta.Bi
- wherein
- a=0.5(1+t-z)
- b=0.5(5-3t-z-2m-5.epsilon.)
- 0.ltoreq.t.ltoreq.0.08
- 0.50.ltoreq.z.ltoreq.0.60
- 0.005.ltoreq.m.ltoreq.0.035
- 0.02.ltoreq..epsilon..ltoreq.0.06
- and .beta. is from 0.0015 to 0.05 molar equivalent.
- 2. A soft lithium titanium-zinc ferrite having a resistivity of at least 10.sup.7 ohm-cm measured at 20.degree. C. and 100 volts, manufactured by forming a mixture of metal oxides and carbonates, wherein said mixture consists essentially of metal oxides and carbonates in proportions calculated as oxides which satisfy the formula:
- Li.sub.a Ti.sub.t An.sub.z Mn.sub.m Fe.sub.b O.sub.4
- wherein
- a=0.5(1+t-z)
- b=0.5(5-3t-z-2m-5.epsilon.)
- 0.ltoreq.t.ltoreq.0.08
- 0.50.ltoreq.z.ltoreq.-0.60
- 0.005.ltoreq.m.ltoreq.0.035
- 0.02.ltoreq..epsilon..ltoreq.0.06;
- crushing said formed mixture; calcining said crushed mixture in an air atmosphere at about 700.degree. C. for about 2 hours; adding to said calcined mixture .beta. molar equivalent of Bi, as the oxide or carbonate, wherein .beta. is from 0.0015 to 0.05; and sintering said mixture of said calcined mixture and said Bi in an oxygen-containing atmosphere at from 950.degree. to 1100.degree. C. for from 1 to 18 hours.
- 3. The ferrite of claim 1 or 2, wherein
- .ltoreq. t.ltoreq.0.06
- 0.52.ltoreq.z.ltoreq.0.58
- 0.03.ltoreq.m.ltoreq.0.035
- 0.055.ltoreq..epsilon..ltoreq.0.060
- 0.010.ltoreq..beta..ltoreq.0.015.
- 4. The ferrite of claim 1 or 2, wherein
- t=0, z=0.55, m=0.035,
- .epsilon.=0.06 and .beta.=0.01.
- 5. The ferrite of claim 1 or 2, wherein
- t=0.05, z=0.55, m=0.035,
- .epsilon.=0.06 and .beta.=0.01.
- 6. A process for preparing soft lithium-titanium-zinc ferrites having a resistivity of at least 10.sup.7 ohm-cm measured at 20.degree. C. and 100 volts, which comprises the steps of:
- (a) crushing a mixture consisting essentially of metal oxides and carbonates in proportions, calculated as oxides, which satisfy the formula
- Li.sub.a Ti.sub.t Zn.sub.z Mn.sub.m Fe.sub.b O.sub.4
- wherein
- a=0.5(1+t-z)
- b=0.5(5-3t-z-2m-5.epsilon.)
- 0.ltoreq.t.ltoreq.0.08
- 0.50.ltoreq.z.ltoreq.0.60
- 0. 005.ltoreq.m.ltoreq.0.035
- 0.02.ltoreq..epsilon..ltoreq.0.06
- and wherein from 0.0015 to 0.05 molar equivalent of Bi, as the oxide or carbonate, is present in said mixture or is added after step (b);
- (b) calcining the crushed powder from step (a) in an air atmosphere for about 2 hours at about 700.degree. C.; and
- (c) sintering the calcined material from step (b) in an oxygen-containing atmosphere at from 950.degree. to 1100.degree. C. for from 1 to 18 hours.
- 7. The process of claim 6, wherein said Bi is added after step (b), and a further crushing step is performed on the resultant bismuth-containing calcined material.
- 8. The process of claim 6, wherein said sintering (c) is carried out at a temperature of about 975.degree. C. for from 8 to 16 hours in an oxygen atmosphere.
Priority Claims (1)
Number |
Date |
Country |
Kind |
76 37624 |
Dec 1976 |
FRX |
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Parent Case Info
This application is a continuation in part of application Ser. No. 859,714 filed Dec. 12, 1977, now U.S. Pat. No. 4,155,863.
US Referenced Citations (4)
Foreign Referenced Citations (4)
Number |
Date |
Country |
2647893 |
May 1977 |
DEX |
2755525 |
Jun 1978 |
DEX |
2269506 |
Nov 1975 |
FRX |
2328677 |
|
FRX |
Non-Patent Literature Citations (1)
Entry |
Agajaman "IBM Tech. Disclosure Bull.", vol. 11, No. 7, Dec. 1968 p. 797. |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
859714 |
Dec 1977 |
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