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Home , Lanthanum oxide

June 19, 1973 / - NI. FAULSTICH ETAL 3,740,242 OPTICAL Original Filed Aug. 31, 1966

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3% 27017 4 ttOF "e75 3,740,242 United States Patent 0 1C6 Patented June 19,, 1973

:1 2 being greater and in a few cases practically equal to the 3,740,242 Slog-content. OPTICAL GLASSES Marga Faulstich, Mainz, and Willy Ritze, Mainz It will be obvious that it is desirable to eliminate thoria Monbach, Germany from compositions, since thoria is often a radio Continuation of abandoned application Ser. No. 1,960, active material. Further and similarly, it will he obviously Jan. 12, 1970, which is a continuation of application desirable to remove beryllia from optical glass composi Ser. No. 576,403, Aug. 31, 1966. This application Mar. tions, since beryllia is toxic, and therefore, a physiologi 4, 1971, Ser. No. 121,167 cally undesirable component. Claims priority, application Germany, Sept. 4, 1965, It has been known in the past to produce thoria- and J 28,924 l0 beryllia-free glasses having optical properties in the same Int. Cl. C03c 3/08, 3/10, 3/30 general range as those indicated to be desirable therefor. US. Cl. 106-54 22 Claims These glasses generally have been prepared with a silica content of at most about 15 percent. In the manufacture ABSTRACT OF THE DISCLOSURE of these glasses, it has been found to be necessary to melt and oxide-free glasses suitable 15 the compositions in platinum crucibles and to carry out to continuous melting and production having the follow the production of optical glass from these compositions ing comparative values: in batch operations, since continuous or automatic pro duction could not be accomplished without devitri?cation Index of refraction: Abbe value of the product. 20 It is therefore an object of this invention to provide nd71d 1.750 ______..._ __ VaVd 37 a novel glass composition. It is another object of this invention to provide a novel and having a composition: glass composition which can be produced continuously Weight percent and/ or automatically. SiOZ ______18.0-23.1 25 It is still a further object of this invention to provide B203 ______7.6-14.8 a novel glass composition which is free from beryllia 31024-1320, ______-_ 27.0-33s and thoria as essential components thereof. BaO ______27.1-46.2 Other and additional objects of this invention will be come apparent from a consideration of this entire speci? La203EEO-P153203 ______.__ 30.7~-62.9 cation, including the claims appended hereto.

CdO ______.._ 0.8-—16.1 In accord with and ful?lling these objects, one aspect ZrOz ._ 1.0-3.5 of this invention includes providing a glass composition CClO-l-Zl‘Og ______23-191) having the following proportions of constituents: 35 Wt. percent This application is a continuation of application Ser. SiOz __ 18-25 No. 1,960, ?led ] an. 12, 1970, which is a continuation of B203 ______7-15 Ser. No. 576,403, ?led Aug. 31, 1966 both of which are SiO2+B2O3 ______-_ 23-35 abandoned. BaO ______.__ __.._ 27-50 This invention relates to a novel class of optical glasses, La2O3 _____ 3-20 and more particularly refers to such glasses which are stable against devitri?cation and are otherwise an im BaO'l‘La203CdO ______._.. 0.5-18 provement over glasses provided by the prior art. ZrOZ _ 0.5-5 It is known to produce optical glasses having various CdO-i-ZrOz ______-5 2-23 indices of refraction and Abbe values. It is further known ‘to produce glasses having as the upper value of their re It is also possible to add up to 6 weight percent, pref fractive indices and Abbe values: erably no more than 5 weight percent, of TiO; and/or Ta2O5 to the glasses, thereby improving the chemical sta nd 1.761 vdVd 41 50 bility and resistance to devitri?cation. The TiOg-content should best amount to from 2 to 4 weight percent on ac~ n, 1.750 v, 37 count of a possibly undesirable yellow coloration. The addition of up to 1 weight percent of A1203 and/ or W03 These known glasses generally contain thorium oxide is also permissible. and/or and, in fact, are often of the With the use of the glass composition as stated above, following compositions: 55 it has been found that optical glasses are produced which (a) Alkaline earth (preferably CaO)— borates, are extremely stable against devitri?cation and are suit silica-free or with a silica content equal to or less than able for continuous and/ or automatic production. The 15 weight percent, the content being production may be of parisons and/or gobs, and further, the composition of this invention can be fused in rela greater than 20 weight percent, plus additions of biva 60 tively large quantity into shaped objects of high optical lent such as ZnO, PbO and CdO 50 weight per quality. It has been found that the glass of this invention cent, plus stabilizing oxides such as Al2O3, ZrOg, TiO'g, has a viscosity of at least about 1200 poises in its plastic Ta2O‘5 and W0, in small quantities. condition during working of the parisons or gobs directly (b) Alkaline earth borates (preferably BaO)-lanthanum from the melt. silicoborates, the lanthanum oxide content amounting 65 According to another aspect of this invention, it has to between 20 and 30 percent when the Bat) content been found practical to replace up to about 8 weight per is less than 50 percent. A stabilization of these glasses cent of the oxide, preferably up to about 5 weight against devitri?cation would be achieved either with percent of the , with oxide, 3 to 15 percent Th02 or with 2 to 15 percent BeO. oxide, oxide and/or up to about 2 weight 70 The above-listed compositions contain B202 and Si02 percent magnesia. Thus, it may be practical to substitute as glass formers, the percentages of boric acid by weight a more inexpensive constituent or mixture of con 3,740,242 stituents for what has heretofore been considered to be thus producing a charge for a 7-liter melt having the fol an essential components. lowing proportions: Further, where the Abbe values are desirably less than Oxides: Weight percent 42, it is necessary to provide at least about 5 percent of SiOZ ______-______18.0 oxide in the composition. Lead oxide can be present 9.0 in proportions of up to about 18 percent, if desired. 5 B203 ______-..______Understanding of this invention will be facilitated by BaO ______.______.______.._.___ 38.1 reference to the accompanying drawing which is a PbO ______graphical representation of the physical properties of various glasses made according to this invention. In this 10 La2O3 ______..__ 17.8 drawing, the arrows indicate the area in which devitrili ZI‘OZ __...______._____.._-__...____...______.___ 3 3 cation glasses can be made. The X’s indicate various co . - Ti02 ______1.9 positions within the scope of the invention which are 1.5 similarly devitri?cation-resistant. T3205 .__.____.____.....__._._...__.______..______W03 ______0.3 The following examples are given by way of illustration 0.3 of this invention only, and should not be construed as 15 AS203 __.__.._....__.__.____....__._.___._....._____.._.__..._ being in any way limiting upon the scope thereof. All lIn a similar manner, the compositions set forth in the parts and percentages are by weight, unless speci?ed to following Table I have been formulated as optical glasses the contrary. having the indices of refraction and Abbe values also in In the production of glass according to each of these dicated in Table I. TABLE I Example N0______10 11 12 Oxide:

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examples, the following procedure was used: As is illustrated by the examples, the glass of the in -free raw materials of the greatest possible purity vention is thorium oxide and beryllium oxide-free optical are used for all optical glasses. The cationic oxide con glass which can be fabricated by continuous or automatic tents of each raw material are determined analytically production without devitri?cation, consisting essentially before use. The weighed-out batch is mixed in a com 40 of the following composition: mercial-type mixer for 5 minutes. The well-mixed batch Weight percent is set in a platinum crucible for about 6 hours at 1270° SiO2 _____-______l8—23.1 C., and then clari?ed at 1300° C. for 2.5 hours. The melt B203 --______.--.___...._.__-__---_..._-_-_ 7.6—14.8 is homogenized by introducing an agitator into the melt siO2+B203 .._.___.___...._._..__._____._..._____._.__... 27—33.8 and stirring it for about 75 minutes from 1280° c. to 45 BaO ______-______27.1-46.2 1605° C. at 120 rpm. The melt can be cast at 1060° C. La2O3 .._...____._____._.______.....____._____...... 3.6-19.2 into block glass in a preheated pot mold, or fed as gobs or BaO-l-La2O3 ..______10-315 parisons to a corresponding blow table or parison mold CdO ______..______.______..__. table. The blocks or gobs or parisons are then cooled ZI‘OZ __..._____.__..._.._.___.____.__._._._.__.___...... _ in a cooling oven from the 628° C. transformation tem 50 CdO-l-ZrO-z ______23-190 perature to room temperature as desired (20-05“ C. and having nd and vd values plotting on a graph of nd per hr.). The melting process can be adapted without against vd in the area bounded by: di?iculty to continuous melting in a platinum tank. "a Va 55 1.761 41.0 EXAMPLE 1 1.750 37.0 1.700 49.8 In order to produce a glass having an index of refrac 1.6935 51.5 tion (nd) of 1.744 and an Abbe value (vd) of about 44, 1.6935 52.5 the following raw materials were used: 60 1.744 44 G‘ What is claimed is: Silicic acid (SiOg) ______-______7214 1. Thorium oxide and beryllium oxide~free optical glass Boric acid ~(H3BO3) ______6394 which can be fabricated by continuous or automatic pro Barium nitrate (Ba(NO3)2) ______.._ 26051 duction without devitri?cation, consisting essentially of Lead oxide (Pb3O4) _____-______205 65 the following composition: (ZnO) ___..______901 Weight percent oxide (CdO) ______2847 SiOZ ______-_-----_-__-______18-23.1 Lanthanum oxide (Lazos) ______7059 B_2O3 ------~-- 7.6-14.8 oxide (ZrOZ) ______1324 70 S1O2+B2O3 ------~------_- 27-33.8 oxide (TiO2) ______763 BaO ______..______27.1-46.2 oxide (Ta2O5) ______..__ 3.6-19.2 oxide (W03) ______642245 Lao.BaO+LaZO3 ..______..______30.7-62.9 oxide (AsZ'O) ______1 --~—--—-——————-—--——---——-—------——-—-—-_ 0.8—16.1 ZrOz ___.--..__-.__._..___---__._..____.__..._--__._._. 1.0-3.5 1As clari?er. 75 cdo+zroa 2.3-19.0 3,740,242 5 6 and having nd and v.1 values plotting on a graph of mi 13. Optical glass as claimed in claim 1, having an in against vd in the area bounded by: dex ofrefraction of 1.750 and an Abbe value of about 37, which has the following composition: Ild Vd 1.761 41.0 S102 ______.._ 22.4 A1203 ______.._ 0.1 1.750 37.0 B203 ______.__ 7.6 LEI-203 ______.._ 3.6 1.700 49.8 , BaO ______.- 27.1 Zr‘lOz ______-_ 2.9 1.6935 51.5 PbO ______.._ 16.4 T102 ...... _....__.___ 2.8 1.6935 52.5 Z110 ______. 2.2 W03 ______0.3 1.744 44 10 Cdo ______.._ 14.3 AS203 ______... 0.3 2. Optical glass as claimed in claim 1, containing ad 14. Optical glass as claimed in claim 1, having an index ditionally up to about 6 weight percent of a member of of refraction of 1.761 and an Abbe value of about 41, the group consisting of TiOz and Ta2O5 and mixtures WhlCh has the following composition: thereof. 3. Optical glass as claimed in claim 2, containing up to S102 ______18.9 1.21203 ______17.8 about 5 weight percent of material of said group. B203 ______9.1 ZI'Og ______.._ 3.5 4. Optical glass as claimed in claim 1, containing in CaO ______.. 0.9‘ T102 ______5.9 addition up to about 1 weight percent of a member se BaO ______33.8 Ta2O5 ______. 4.0 lected from the group consisting of AlzOs-and W03 and 20 PbO ______.__. 0.5 W03 ______0.4 mixtures thereof. ZnO ______1.2 AS203 ______.. 0.4 5. Optical glass as claimed in claim 1, wherein up to CdO ______.. 3.6 about 8 weight percent of said barium oxide is replaced by at least one member selected from the group consisting 15. Optical glass as claimed in claim 1, having an index of refraction of 1.6935 and an Abbe value of about 52.5, of CaO, SrO, ZnO and up to about 2 weight percent 25 MgO. which has the following composition: 6. ‘Optical glass as claimed in claim 1, containing in addition up to about 18 weight percent PbO. ‘ Si02 ______19.0 La2O3 ______17.7 7. Optical glass as claimed in claim 6, wherein said B203 ______14.8 Zro2 ______1.0 BaO ______45.2 W03 ______0.3 lead oxide is present in a proportion of at least about 5 30 weight percent and the Abbe value is less than about 42. ZnO ______0.4 AszO3 ______0.6 8. Optical glass as claimed in claim 1, containing up CdO ______1.3 to about 1 weight percent of at least one alkali metal 16. Optical glass as claimed in claim 1, having an index oxide. of refraction of 1.700 and an Abbe value of about 49.8, 9. Optical glass as claimed in claim 1, having an index 35 of refraction of 1.6935 and an Abbe value of about 51.5, which has the following composition: which has the following composition: SiOz ______20.1 La2O3 ______12.0 B203 ______.__. ZI‘O2 ______1.1 S102 ______21.4 CdO ______.._ 4.9 BaO ______46.2 TiOz ______.. 1.5 B203 ______.._. 11.0 Lagos ______12.4 40 PbO ______0.8 W03 ______0.1 LizO ______- 0.5 ZrOz ______2.9 Z110 ______2.4 AS203 ______.._. 0.3 CaO ______3.6 W03 ______0.3 CdO _-. ______2.6 13.10 ______42.7 AS203 ______0.3 17. Optical glass as claimed in claim 1, having an index of refracnon of 1.717 and an Abbe value of about 48.0, 10. Optical glass as claimed in claim 1, having an index which has the following composition: of refraction of 1.717 and an Abbe value of about 48, which has the following composition: Si02 ______21.0 Lagos ______17.5 B203 ______..- 9-9 ZI'02 ______.. 2.2 sio2 ______20.2 LazOg ______19.2 BaO ______38.1 TiO2 ______1.4 B203 ______21-02 ______.. 2.4 50 ZnO ______2.4 W03 ______0.3 C210 ______.._. 0.7 T102 ______2.3 CdO ______6.8 As2O3 ______0.3 BaO ______.._ 41.3 T3205 ______... 0.8 A1203 ______.. 0.1 Z110 ______.. 0.1 W03 ______... 0.4 CdO ______. 1.1 AS203 ______0.3 18. Optical glass as claimed in claim 1, having an index A1203 ______... 0.1 . of refraction of 1.717 and an Abbe value of about 47.1, 11. Optical glass as claimed in claim 1, having an index which has the following composition: of refraction of 1.750 and an Abbe value of about 46, which has the following composition: B203 ______- --21-6 1.3.203 ______CaO ______.. 1.1 TitOz ______.._. 2.2 sio2 ______- 23.1 A1203 ______0.1 60 B210 ______.._ T3205 ______.. 1.3 B210B203 ______.__-__ 33.69.2 Z1702143-203 ______.._.__ 2.9 ZnO ______0.2 W03 ______0.4 Cd() ______0.8 As203 ______0.3 Z110 ______1.8 T102 ______1.0 A1203 ______.._ 0.1 ______AS203 ______.. 65 19. Optical glass as claimed in claim 1, having an index 12. Optical glass as claimed in claim 1, having an of refraction of 1.720 and an Abbe value of about 46.0, index of refraction of 1.744 and an Abbe value of about which has the following composition: 44, which has the following composition: Si02 ______.._ 19.3 A1203 ______0.1 S102 ______... 18.0 1.3203 ______17.6 70 CaO ______.____ 9.21.6 Zr02Ida-203; ______... 2.9 B203 ______... 9-0 Z102 ______3.3 B310 ______38.1 T102 ______.. 1.9 BaO ______‘_ 45.4 TiOz ______1.5 Pb0______0.5 Ta2O5 ______1.5 PbO ______.._... 3.2 W03 ______0.4 Z110 ______.. 2.2 W03 ______. 0.5 ZnO ______2.4 AS203 ______.. 0.3 CdO ______7.1 AS203 ______... 0.3 75 CdO ______1.6 3,740,242

20. Optical glass as claimed in claim 1, having an of refraction of 1.744 and an Abbe value of about 44, index of refraction of 1.743 and an Abbe value of about which has the following composition:

43.9, which has the following composition: SiOz ______18.0 LazOa ______17.8 B203 ______9.0 ZrO2 ______3 . 3 Slog ______18.7 ZI'Og ______3 .3 BaO ______._ 38.1 Tio; ______.... 1.9 B203 ______10.4 T103 ______.__ 4.3 PbO ______.'. 0.5 T3205 ______1 CaO ______.... 1.1 T3205 ______. 2.8 ZnO ______2.2 W03 ______0.3 BaO ______38.7 wo3 ______0.5 CdO ______7.1 AS203 ______-_ 0-3 CdO ______.__ 1.0 AS303 ______0.3 References Cited 1.3203 ______-.. 10 UNITED STATES PATENTS 21. Optical glass as claimed in claim 1, having an 2,523,362 9/1950 Fraser et a1. ______106—54 index of refraction of 1.735 and an Abbe value of about 2,678,281 5/1954 Geifeken et al ______106-47 X 41.6, which has the following composition: 2,967,779 1/ 1961 Izumitari ______106-—5 4 15 FOREIGN PATENTS sioz ______22.1 A1203 ______0.1 B203 ______8.9 La2O3 ______._.. 8.3 686,708 1/ 1953 Great Britain ______10‘6—54 CaO ______._ 1.8 ZrO2 ______2.9 , 55,355 9/1943 Netherlands ______106-—54 BaO ______. 29.9 Tioz ______..- 2.4 1,047,994 12/ 1958 Germany ______106—-47 20 PbO ______._ 7.9 wo3 ______0.3 WINSTON A. DOUGLAS, Primary Examiner ZnO ______2.4 AS203 ______.... M. L. BELL, Assistant Examiner CdO ______12.7 US. Cl. X.R. 22. Optical glass as claimed in claim 1, having an index 106——47 Q, 53 UNITED STATES PATENT omen CERTIFICATE OF CQRECTHN

Patent No. 3,740 .242 ' Dated June 19, 1973 _ ‘

lnventol-(s) Marga Faulstich et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 4, after "Germanyi" insert —- JENAer

Glaswerk Schott G Gen. , Mainz, Germany —— . Column 4, Table I,

"l . 764" should read -— 1.761 -— .

Signed and sealed this 19th day of February 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ‘ C MARSHALL DANN Attestlng‘ offlce’fr Commissioner of Patents

FORM PC4050 (‘0'69 uscoMM-Dc scan-Poo i’ U.Sv GOVERNMENT PRINTlNG OFFICE; l9‘, °'-J‘6"!!"