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US5973589A
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Zno varistor of low-temperature sintering ability
Assignee: National Science and Technology Council
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Filing: 1998-06-23
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Granted: 1999-10-26
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Expires: 2018-06-23
Abstract
Abstract Zinc oxide (ZnO) varistors containing vanadium oxide as the principal additive and one or more cobalt oxides and/or manganese oxides additives exhibit excellent nonlinear current-voltage characteristics. Preferably the varistor compositions are capable of being sintered at a temperature of from 900 DEG C. to 950 DEG C. The low-firing capability of the newly developed materials is attractive for the application in the multilayer chip varistor, because it can cofire with the silver (Ag) or palladium/silver (Pd/Ag) internal electrode instead of using the expensive palladium (Pd) or platinum (Pt) metal. With an appropriate combination of ZnO, vanadium oxide (V2O5) and other oxide additives, a varistor sintered at 900 DEG C. for 2 hours is obtained with a nonlinear coefficient>50 and a leakage current<20 mu A/cm2.
Inventors
- 👤 Tai-Bor Wu
- 👤 Jyh-Kuang Tsai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:43
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/10; H01C7/105; H01C7/108; H01C7/112; C; C04; C04B; C04B35/00; C04B35/01; C04B35/453; C04B35/622; C04B35/626; C04B35/62605; C04B35/62645; C04B35/62675; C04B2235/00; C04B2235/02; C04B2235/30; C04B2235/32; C04B2235/3201; C04B2235/3203; C04B2235/3205; C04B2235/3213; C04B2235/3215; C04B2235/3224; C04B2235/3225; C04B2235/3227; C04B2235/3231; C04B2235/3239; C04B2235/3251; C04B2235/3256; C04B2235/3258; C04B2235/3262; C04B2235/3263; C04B2235/327; C04B2235/3275; C04B2235/3277; C04B2235/3279; C04B2235/3298; C04B2235/36; C04B2235/365; C04B2235/60; C04B2235/604; C04B2235/65; C04B2235/656; C04B2235/70; C04B2235/74; C04B2235/77; C04B2235/78; C04B2235/786
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
79 words
A bulk-type zinc oxide varistor comprising a ceramic body capable of being sintered at a temperature of 900° C. to 950° C. which comprises zinc oxide as a principal constituent, 0.1-2 mol % of vanadium oxide as a principal additive to form a vanadium rich intergranular phase, and 0.05-0.5 mol % of manganese oxide and 0.05-0.5 mol % of cobalt oxide as auxiliary constituents when calculated in terms of Mn 3 O 4 and Co 3 O 4 respectively.
Claim 2
Dependent Claim
79 words
A bulk-type zinc oxide varistor comprising a ceramic body capable of being sintered at a temperature of 900° C. to 950° C. which comprises zinc oxide as a principal constituent, 0.1-2 mol % of vanadium oxide as a principal additive to form a vanadium rich intergranular phase, and 0.05-0.5 mol % of manganese oxide and 0.05-0.5 mol % of cobalt oxide as auxiliary constituents when calculated in terms of Mn 3 O 4 and Co 3 O 4 respectively.
Claim 3
Dependent Claim
41 words
The zinc oxide varistor according to claim 1 further comprising 0.005-0.1 mol % of a high-valence metal oxide selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , MoO 3 , and WO 3 .
Claim 4
Dependent Claim
51 words
The zinc oxide varistor according to claim 1 further comprising 0.01-0.1 mol % of a large ionic radius metal oxide selected from the group consisting of SrCO 3 , BaCO 3 , La 2 O 3 , Y 2 O 3 , Pr 6 O 11 , and the mixture thereof.
Claim 5
Dependent Claim
19 words
The zinc oxide varistor according to claim 1 further comprising 0.005-0.05 mol % of Bi 2 O 3 .
Claim 6
Dependent Claim
21 words
The zinc oxide varistor according to claim 1 further comprising 0.1-2 wt % of PbO--B 2 O 3 --SiO 2 glass.
Claim 7
Dependent Claim
37 words
The zinc oxide varistor according to claim 5, wherein the PbO--B 2 O 3 --SiO 2 glass comprises 35-70 wt % PbO, 5-25 wt % B 2 O 3 , and 20-50 wt % SiO 2 .
Claim 8
Dependent Claim
85 words
The zinc oxide varistor according to claim 1 further comprising 0.005-0.1 mol % of a high-valence metal oxide selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , MoO 3 , and WO 3 , and 0.01-0.1 mol % of one or more large ionic radius metal oxides selected from the group consisting of SrCO 3 , BaCO 3 , La 2 O 3 , Y 2 O 3 , Pr 6 O 11 , and the mixture thereof.
Claim 9
Dependent Claim
51 words
The zinc oxide varistor according to claim 1 further comprising 0.005-0.1 mol % of a high-valence metal oxide selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , MoO 3 , and WO 3 , and 0.005-0.05 mol % of Bi 2 O 3 .
Claim 10
Dependent Claim
53 words
The zinc oxide varistor according to claim 1 further comprising 0.005-0.1 mol % of a high-valence metal oxide selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , MoO 3 , and WO 3 , and 0.1-2 wt % of PbO--B 2 O 3 --SiO 2 glass.
Claim 11
Dependent Claim
38 words
The zinc oxide varistor according to claim 1 further comprising 0.005-0.05 mol % of a low-valence metal oxide selected from the group consisting of Li 2 CO 3 , Na 2 CO 3 , and the mixture thereof.
Claim 12
Dependent Claim
15 words
The zinc oxide varistor according to claim 1 further comprising 0.05-0.5 mol % of NiO.
Claim 13
Dependent Claim
38 words
The zinc oxide varistor according to claim 7 further comprising 0.005-0.05 mol % of a low-valence metal oxide selected from the group consisting of Li 2 CO 3 , Na 2 CO 3 , and the mixture thereof.
Claim 14
Dependent Claim
15 words
The zinc oxide varistor according to claim 12 further comprising 0.05-0.5 mol % of NiO.
Claim 15
Dependent Claim
38 words
The zinc oxide varistor according to claim 8 further comprising 0.005-0.05 mol % of a low-valence metal oxide selected from the group consisting of Li 2 CO 3 , Na 2 CO 3 , and the mixture thereof.
Claim 16
Dependent Claim
15 words
The zinc oxide varistor according to claim 14 further comprising 0.05-0.5 mol % of NiO.
Claim 17
Dependent Claim
38 words
The zinc oxide varistor according to claim 9 further comprising 0.005-0.05 mol % of a low-valence metal oxide selected from the group consisting of Li 2 CO 3 , Na 2 CO 3 , and the mixture thereof.
Claim 18
Dependent Claim
15 words
The zinc oxide varistor according to claim 16 further comprising 0.05-0.5 mol % of NiO.
Claim 19
Dependent Claim
74 words
A multilayer chip zinc oxide varistor comprising a ceramic body sintered at a temperature of 900° C. to 950° C. which comprises zinc oxide as a principal constituent, 0.1-2 mol % of vanadium oxide as a principal additive, 0.05-0.5 mol % of manganese oxide and 0.05-0.5 mol % of cobalt oxide as auxiliary constituents when calculated in terms of Mn 3 O 4 and Co 3 O 4 respectively, and silver (Ag) internal electrode.
Claim 20
Dependent Claim
74 words
A multilayer chip zinc oxide varistor comprising a ceramic body sintered at a temperature of 900° C. to 950° C. which comprises zinc oxide as a principal constituent, 0.1-2 mol % of vanadium oxide as a principal additive, 0.05-0.5 mol % of manganese oxide and 0.05-0.5 mol % of cobalt oxide as auxiliary constituents when calculated in terms of Mn 3 O 4 and Co 3 O 4 respectively, and silver (Ag) internal electrode.
Claim 21
Dependent Claim
20 words
The multilayer chip zinc oxide varistor according to claim 18, wherein the Ag internal electrode is replaced by palladium/silver (Pd/Ag).
Claim 22
Dependent Claim
43 words
The multilayer chip zinc oxide varistor according to claim 18 further comprising 0.005-0.1 mol % of a high-valence metal oxide selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , MoO 3 , and WO 3 .
Claim 23
Dependent Claim
53 words
The multilayer chip zinc oxide varistor according to claim 18 further comprising 0.01-0.1 mol % of a large ionic radius metal oxide selected from the group consisting of SrCO 3 , BaCO 3 , La 2 O 3 , Y 2 O 3 , Pr 6 O 11 , and the mixture thereof.
Claim 24
Dependent Claim
21 words
The multilayer chip zinc oxide varistor according to claim 18 further comprising 0.005-0.05 mol % of Bi 2 O 3 .
Claim 25
Dependent Claim
23 words
The multilayer chip zinc oxide varistor according to claim 18 further comprising 0.1-2 wt % of PbO--B 2 O 3 --SiO 2 glass.
Claim 26
Dependent Claim
87 words
The multilayer chip zinc oxide varistor according to claim 18 further comprising 0.005-0.1 mol % of a high-valence metal oxide selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , MoO 3 , and WO 3 , and 0.01-0.1 mol % of one or more large ionic radius metal oxides selected from the group consisting of SrCO 3 , BaCO 3 , La 2 O 3 , Y 2 O 3 , Pr 6 O 11 , and the mixture thereof.
Claim 27
Dependent Claim
40 words
The multilayer chip zinc oxide varistor according to claim 18 further comprising 0.005-0.05 mol % of a low-valence metal oxide selected from the group consisting of Li 2 CO 3 , Na 2 CO 3 , and the mixture thereof.
Claim 28
Dependent Claim
17 words
The multilayer chip zinc oxide varistor according to claim 18 further comprising 0.05-0.5 mol % of NiO.
Claim 29
Dependent Claim
40 words
The multilayer chip zinc oxide varistor according to claim 22 further comprising 0.005-0.05 mol % of a low-valence metal oxide selected from the group consisting of Li 2 CO 3 , Na 2 CO 3 , and the mixture thereof.
Claim 30
Dependent Claim
17 words
The multilayer chip zinc oxide varistor according to claim 25 further comprising 0.05-0.5 mol % of NiO.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-10-25 | 2003-04-26 | 2003-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-10-25 | 2007-04-26 | 2007-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-10-25 | 2011-04-26 | 2011-10-26 | $7700.00 | Window Closed / Lapsed |