CZ302723B6 - Crystal glass exhibiting coefficient of refraction higher than 1.53 without lead, barium and arsenic compounds - Google Patents

Abstract

The present invention relates to crystal glass having coefficient of refraction higher than 1.53, high mechanical strength, being free of lead, barium and arsenic compounds and ensuring a maximum health safety wherein the invention is characterized in that the crystal glass consists of 55 to 70 percent by weight of SiOi2, 0.05 to 3.5 percent by weight of Lii2O, 2 to 15 percent by weight of Nai2O, more than 3 percent by weight and less than 5 percent by weight or more than 15 percent by weight and less than 19 percent by weight of Ki2O, 5 to 10 percent by weight of CaO, more than 1 percent by weight and less than 4 percent by weight or more than 7 percent by weight and less than 8 percent by weight of ZnO, 0.1 to 3.5 percent by weight of Bi2Oi3, 0.1 to 3.5 percent by weight of Ali2Oi3, 0.1 to 3.5 percent by weight of TiOi2, less than 3.5 percent by weight of ZrOi2, 0.05 to 1.5 percent by weight of Gdi2Oi3, 0.05 to 1 percent by weight of Pi2Oi5, and 0.1 to 1 percent by weight of Sbi2Oi3.

Description

Crystal glass with a refractive index higher than 1,53, containing no lead, barium and arsenic compounds

Technical field

BACKGROUND OF THE INVENTION The present invention relates to crystal glass having a refractive index of greater than 1.53 and high mechanical strength, free of lead, barium and arsenic compounds, for use in the manufacture of imitation jewelery and chandelier blanks and articles thereof. This glass is also intended for the manufacture of glass chandeliers and household items.

This glass has a very good processability in melting, shaping and polishing, achieves a brightness of at least 93%, a density of at least 2.54 g / cm ³ and a Young's modulus above 90 GPa, and is characterized by increased chemical resistance, reduced solarization and reduced toxicity. maximum health safety during normal use of glass products.

BACKGROUND OF THE INVENTION

Quality crystal glasses must meet the conditions for their use in terms of optical parameters, mechanical parameters and other physical “Chemical properties” as well as in terms of health and safety criteria. Given the significant change in the evaluation of crystals after 1991, in particular in terms of health, environmental impact and toxicity to consumers, manufacturers endeavor to modify the characteristics of modern consumer and decorative glasses to meet the above requirements. This can be achieved by varying the composition of the glass base matrix.

Currently, four types of crystal glasses are produced according to Directive 69/493 / ECC, which are high-lead crystal, lead crystal, crystalline and crystal glass. However, all types of these glasses, by definition, contain either lead oxide and / or barium oxide. Current European Union legislation regulates the use of heavy metal compounds such as Cd, Pb, Hg and Cr.

An example of such regulation is EU Directive 2002/95 / ECC (Restriction of Use of Certain Hazardous Substances in Electrical and Electronic Equipment - RoHS), issued January 27, 2003 and modified August 18, 2005 (entered into force July 1, 2006) toxic metals in electrical and electronic equipment. This Directive restricts the use of these metals in incandescent lamps, discharge lamps, glass solders, as well as glass accessories for luminaires and consumer electronic items. The EU Directive 94/62 / ECC also requires manufacturers to limit the harmful effects of heavy metals in the production and use of glass containers.

Another restriction on the use of toxic metals is the Consumer Product Safety Improvement Act (CPSLA), published in 2008, addressing the restrictions set by the Consumer Product Safety Commission (CPSC) that products that children under the age of 12 must meet. Part 101 of the Directive requires that after 10 February 2009, products designed or intended for children under 12 years old must not contain more than 600 ppm of lead (lead ions), since 14 August 2009 they must contain less than 300 ppm of lead and starting 14. By August 2011, the limit can be reduced to 100 ppm and below. Costume jewelery and ornaments are intended for both adults and children, and manufacturers must guarantee health safety and toxicological "harmlessness" to all users.

Lead crystal is characterized in particular by a high specific gravity> 2.9 g / cm ³ , a high refractive index> 1.545, a high optical dispersion. The technological properties are also favorable.

Health-safe glasses can be divided into two groups according to density and refractive index. The first group consists of glasses whose density and refractive index are comparable with lead crystal. These glasses are listed in Table 1 below. The second group consists of glasses whose density is not complied with according to ISO 302723 B6 Nice 69/493 / ECC and whose refractive index is comparable or lower with lead crystal. These glasses are listed in Table 2 and Table 3 below.

As shown in the tables above, the following 5 oxides were most commonly used to replace PbO and BaO in the glass skeleton: MgO, CaO, SrO, ZnO, La ₂ O ₃ , Bi ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , Nb ₂ O _with Ta ₂ O ₅ , Y ₂ O ₂ ,

Yb ₂ O ₂ and WO 1. All compounds used in the skeleton of safe glass have low toxicity or are nontoxic.

According to the patents granted, the composition of the group of glasses listed in Table I contains neither toxic PbO 10 nor BaO. The Baccarat patent uses ZnO, SrO and CaO oxides to replace PbO. British Glass's patent is based on the use of Bi ₂ O ₂ , TiO ₂ and SrO. Nachtmann stabilizes the combination of TiO ₂ , ZnO and SrO. Swarovski mainly uses combinations of oxides

ZnO and CaO. All these glasses are close to lead crystal type in both density and refractive index.

Table I: Composition of glasses having a refractive index> 1.54 and a density> 2.63 g / cm ³

Oxide (mass%) Patent owner / Patent no. Baccarat British Glass Nachtmann Swarovski ^b EP 0553586 A1 GB 2280432 A DE 10258923 A1 EP 1725502 A1 SiO ₂ 53-58 50-65 55-68 50-60 Li ₂ O 0-0.3 Σ M ₂ O 12-23 - 0.5-3 Na ₂ O 4,5-7,5 5-12 12-15 K ₂ O 6-10 9-15 <3 MgO - - - <2 CaO 0-9 0-15 ⁸ - 4-11 SrO 0-12 1-20 <5 CaO replacement BaO - - - - ZnO 16-21 0-15 ⁸ 3-10 8-16 B2O3 0-1,2 0-15 ’ - 0,6-4 ai ₂ o ₃ 0-1,5 0-15 ⁸ - 0,25-5 La ₂ O ₃ 0-3 0-15 ⁸ - <5 Bi ₂ O ₃ - 1-20 - <3 TiO ₂ 0-2 1-15 8,5-14 <5 ZrO ₂ - 0-15 ⁸ - <3 SnO ₂ 0-2,5 - - Yes Nb ₂ O ₆ - - - <1 Ta ₂ O ₅ - - - <1 Y ₂ O ₃ - - - <3 Yb2O ₃ - - - <1 WO ₃ - - - <3 Čeřivo Sb., As, Ce Sb., As, Ce Sb., As Coll Guaranteed values of quantities plg / cm ³ ] > 2,9 £ 2.7 > 263 > 2,7 n _D > 1,545 > 1.55 > 1.54 > 1.55

The glass further comprises one or more oxides of the group of said oxides by weight in total up to 15% by weight.

^{b the} total content of oxides Pb, Ba, As lies below 0,1%, the total content of oxides Ti and La below 25 5% and the total content of oxides Nb, Ta, Yb, Y, W, B1, Zr is below 5%, it contains not more than% of each of the oxides Nb, Ta, Yb and not more than 3% of each of the oxides Y, W, Bi, Zr. The total weight content of ZnO and CaO is greater than 15%. CaO is partially replaced by SrO. The glass further contains

0.5-3% of Li ₂ O. The sum of the weight content of Na ₂ O and Li ₂ O is below 17%. The total weight content of the other components, apart from Sb ₂ O ₂ , Nd ₂ O ₅ and Er ₂ O ₂ , is below 2%.

The glass compositions of the group shown in Tables 2 and 3 also contain no toxic PbO or BaO according to the patents granted and utility model.

Table 2: Composition of glasses having a refractive index> 1.52 and a density> 2.43 g / cm ⁵

Oxide (mass%) Patent holder / Patent no. Inn Crystal Glass Moser Moravian glassworks Květná Nachtmann EP 0547263 A1 CZ 294797 B6 CZ 19984 U1 DE 19936699 A1 SiO ₂ 65-70 71,5-76,5 65,5-75,5 59-71 Li ₂ O - - - 0,01-2 Na ₂ O 4-12 5-9 6-10 3-15 K ₂ O 4-12 8-12 8-12 0,08-11 MgO - - <2 0,5-8 CaO 6-9 5-9 5-9 Table 2-10 SrO - - 1-5 0,001-0,1 BaO - - - - ZnO 4-7 0,5-3,5 <4 0,01-11 B ₂ O ₃ 0,5-5 0,5-3,5 <2 0,01-3 ai ₂ o ₃ 1-5 0,1-2,1 <2 0,01-4 la ₂ O ₃ - 0,5-5,5 0,001-4 Bi ₂ O ₃ - - - - TiO ₂ 1-6 - - 0,01-8 ZrO ₂ 1-6 - - - SnO ₂ - - - 0,001-3 ŇbjOs - - - - Ta ₂ O ₅ - - - - Y ₂ O ₃ - - - - Yb ₂ O ₃ - - - - WO ₃ - - - - Čeřivo Coll Coll Coll Sb, As, SO ?, F Guaranteed values of quantities p [g / cm ³ ] > 2.45 > 2.43 > 2.52 > 2.45 n _D £ 1.52 > 1.52 > 1.52 > 1.52

io Company (nn Crystal Glass introduces glass based on CaO, ZnO, ZrO ₂ and / or TiO ₂ modifiers. Moser introduces glass based on CaO and ZnO oxides. Utility model of Moravian glassworks Květná introduces glass based on a combination of CaO, MgO, SrO , ZnO and La ₂ O ,. Nachtmann All patents mentions the presence of oxides of Ca, MgO, ZnO, TiO _2, La ₂ O ₃ and SnO _2, and a specific water content.

-3 CZ 302723 B6

Table 3: Composition of glasses having a refractive index> 1,52 and a density> 2,45 g / cm ´

Oxide (wt%) Patent owner / Patent no. Rona Schott ^a Toyo-sasaki Glass Favrot, G. A., Truyol, A. SK 285523 B6 EP 0564802 A1 EP 2022767 A1 EP 0701976 A1 S1O2 65,1-71,9 50-75 62-65 65-73 Li ₂ O - 0-5 1,5-2,5 Na ₂ O 8-14 2-15 10-12 4-8 K ₂ O 6.5-9.9 5-15 8-10 0,2-0,7 MgO £ 0.6 0-5 - 2-5 CaO 8,6-13 3-12 3-4,2 5-8 SrO - 0-7 2-3,2 - BaO - - - - ZnO 0,5-3,6 0-7 6-7,2 1,2-3 B2O3 - 0-10 - 5-8 ai ₂ 0 ₃ 0,01-3 0-5 2-3,2 2,5-4 La ₂ O3 - - 0-1,2 - BI2O3 - - - - TÍO ₂ - 0-8 2,2-3 0,3-0,8 ZrO ₂ 0,01-2,1 0-5 0-1,2 1,1-2,5 SnO ₂ - - 0-1,2 - Nb ₂ O ₅ - 0,1-5 - - Ta ₂ O ₅ - 0-5 - - Y2O3 - - 0-1,2 - Yb _of O ₃ - - - - WO ₃ - - - - Čeřivo Coll Sb., F Coll Ce, SO? Guaranteed values of quantities Pig / cm ³ ] 22.45 * 2.45 22.6 neuvedeno n _Ď 21.52 > 1.52 21.53 neuvedeno

^{i the} total mass content of TiO ₂ + ZrO ₂ + Nb ₂ Os + Ta ₂ O ₃ oxides is in the range of 0.3 to 12%

Slovak producer of crystal Rona protects glass based on high content of CaO and presence of ZnO, ZrO? and MgO. Schott Glaswerke is based on an alkali-calcium skeleton which is also modified by a combination of oxides of MgO, ZnO, TiO ₂ , ZrO ₂ , Nb ₂ O ₅ and Ta ₂ O ₅ .

Toyo-sasaki Glass introduces glass containing ZnO, CaO, SrO, TiO ₂ , La ₂ O ₃ , SnO ₂ and Y ₂ O ₃ . Finally, the inventors GA Favrot and A. Truyol report glass with oxides of CaO, MgO, ZnO, ZrO ₂ and TiO ₂ . This group of glasses exhibits a lower density than lead crystal i5, and also the refractive index ranges from lower values to values comparable to those of lead crystal glasses.

Although the above-described lead-free glasses have largely satisfactory properties, they still have these drawbacks. Some contain toxic As ₂ O ₃ as a fining agent, some use expensive and discreet components SrO, La ₂ O ₃ , Bi ₂ O ₃ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , Y ₂ O ₃ , Yb ₂ O ₃ , WO _3, etc. Another disadvantage in some of the above-mentioned patent documents are the high melting temperatures, the relatively high content of TiO ₂ , ZrO ₂ , B ₂ O ₃ , causing a yellowish hue of the resulting glass, respectively. problems associated with bulk and / or surface crystallization of glass. The high ZnO content often causes increased corrosion of the refractory materials used to build the melting aggregates.

It is an object of the invention to overcome these drawbacks.

-4 CZ 302723 B6

SUMMARY OF THE INVENTION

The present invention is a crystal having a refractive index greater than 1.53 and a high mechanical strength, compounds containing lead, barium and arsenic, which ensures maximum health bez5 pečnost whose principle consists in that the weight consists of up to 70% SiO _2,

0.05 to 3.5% Li ₂ O, up to 15% Na 2 O, including more than 3% and less than 5% or more than 15% and less than 19% K ₂ O, up to 10% CaO, more than 1% and less than 4% or more than 7% and less than 8% of ZnO,

0.1 to 3.5% B ₂ O ₃ ,

0.1 to 3.5% Al ₂ O ₃ , is 0.1 to 3.5% TiO ₂ , less than 3.5% ZrO ₂ ,

0.05 to 1.5% Gd ₂ O ₃ ,

0.05 to 1% P ₂ O ₅ ,

0.1 to 1% Sb ₂ O ₃ , while ZnO content in the lower range is preferable for lower refractive index glasses, while K ₂ O content in both lower and higher ranges is preferable, while ZnO content is preferable for higher refractive index glasses. lying in a higher range with a K ₂ O content lying in a lower range, as appropriate, and is also expressed in the examples below.

Accordingly, the present invention provides a composition of crystal glass having a high refractive index, high mechanical strength and satisfactory crystallization characteristics.

The crystal glass parameters according to the invention are given in Table 4.

Table 4: Glass parameters according to the invention

Parameter name Value refractive index n _D > 1.53 Brightness [% J > 93 Density [g / cm ³ ] > 2,5 Young's modulus E [GPa] > 90 Melting point / logn = 2 / rci <1380 Processing temperature / log η = 4 / t ° C] <1010 Softening temperature (logq = 7.65) [° C] <740 Temperature fiquidus [•C] <1000 Maximum crystallization rate temperature rc] <940 Maximum crystallization rate [pm / min ^ 1.5 Hydrotytic resistance [ml HCl [C = = 0.01 mol / l]] <0.80

The basic skeleton of this crystal glass is alkali-lime glass, which is toxically harmless.

To this batch are not deliberately added components no harmful lead, barium and / or arsenic, which may in the final glass composition appear in a number of hundredth of percent impurity from used raw materials, which may be in particular oxides of ZnO and Sb ₂ O _3rd The basic skeleton of the glass composition is modified with oxides of ZnO, TiO ₂ , resp. ZrO ₂ , which significantly increase

-5GB 302723 B6 together with Li ₂ O and CaO refractive index. The oxides of Al ₂ O ₃ and B ₂ O ₃ improve the hydrolytic resistance and together with the oxides LUO, ZrO ₂ , TiO ₂ and CaO also mechanical strength. The higher the content of CaO and ZnO in the glass, the higher the refractive index, but also higher temperature of liquidus and the value of crystallization rate increases, while the effect of both oxidizes on crystallization parameters roughly comparable. However, when melting on electric baths, zinc oxide reduces the specific electrical resistance at the same temperature, which results in greater corrosion of the electrodes and the refractory material, despite its higher cost. He is also responsible for the corrosion of refractory materials in the case of gas units. On the other hand, it has a more favorable effect on hydrolytic resistance. From an economic point of view, it is therefore preferable to always keep the CaO content as high as possible and to reduce the amount of ZnO as low as possible while also replacing the largest proportion of the more expensive potash and soda with cheaper limestone. However, this substitution is limited by increasing crystallization characteristics. Surprisingly and unexpectedly, this was achieved by using a combination of Gd ₂ O ₃ and P ₂ O ₅ oxides as follows:

a preferred crystal glass according to the invention comprises 0.05-0.8% Gd ₂ O ₃ and 0.05-0.8% P ₂ O ₅ at a Gd ₂ O ₃ / P ₂ O ₅ ratio of at least 1: 1 by weight, preferably the crystal glass according to the invention comprises 0.05-0.15% Gd ₂ O ₃ and 0.1-0.8% P ₂ O ₅ at a ratio of Gd ₂ O ₃ / P ₂ O _{5 of} at least 1: 2, preferably crystal the glass according to the invention contains by weight 0.1% Gd ₂ O ₃ and 0.2-0.8% P ₂ O ₅ at a Gd ₂ O ₃ / P ₂ 0 ₅ ratio of at least 1: 2.

At such selected ratios, both the liquidus temperature and the maximum crystallization rate temperature, and in particular the maximum crystallization rate value, decreased significantly. It was also surprising to improve the hydrolytic resistance and abrasion. Unexpected was also an improvement in enamel clarification and product formability.

This combination of oxides Gd ₂ O ₃ and P ₂ C> 5 can be used with similar results for all types of industrially produced glasses.

This glass with a combination of oxides Gd ₂ O ₃ and P ₂ O _5, besides being free of harmful oxides Pb, Ba and As, which some glasses according to the above mentioned patent documents meet, allows to achieve high refractive index and high mechanical strength at relatively low ZnO contents, which will reduce the corrosion of refractory materials of the melting aggregates used, mainly due to ZnO and K ₂ O. A particular advantage of the invention is that expensive and questionable SrO, La ₂ O ₃ , Bi ₂ components need not be used to achieve high refractive index. O ₃ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , Y ₂ O ₃ , Yb ₂ O ₃ , WO _3, etc., as is the case in particular with the glasses according to the aforementioned patent documents, utility model and other existing patents, on lead-free glass.

The glass according to the invention is clarified by a conventional fining mixture of Sb ₂ O ₃ and / or various kinds of antimony salts together with sodium or potassium nitrate. However, conventional amounts of CeO ₂ may be used together with nitrate or conventional amounts of sulfates, fluorides, as well as all possible conventional known combinations of the above components in conventional concentrations.

The glass according to the invention is bleached with the known components and their usual possible and known combinations in conventional concentrations. Components or combinations thereof from the group consisting of CeO ₂ , Er ₂ O ₃ , Nd ₂ O ₃ , NiO, CoO, manganese and Se compounds and selenium compounds may be used.

Accordingly, the crystal glass according to the invention is preferably clarified and bleached with conventional clarifying and bleaching components and / or mixtures thereof in conventional concentrations.

-6GB 302723 B6

The glass of the invention contains conventional amounts of Fe ₂ O _{3 R} which corresponds to a normal contents in crystal glasses and that the glass according to the invention loaded with impurities from the raw materials used and the content of Fe ₂ O ₃ of the shards.

The glass according to the invention contains a minimum content of MgO introduced into the glass as an impurity from the limestone and sand used.

DETAILED DESCRIPTION OF THE INVENTION 10

Examples of embodiments of the invention together with the detected glass parameters are given in Table 5. The glass according to Example 1 does not meet the requirement of Directive 69/493 / ECC that the total weight content of oxides PbO, Ba, ZnO and K ₂ O must be at least 10 however, it satisfies the desired values of the monitored quantities as well as the glasses according to the embodiments 2 and 3 which meet this requirement. The composition according to the embodiment 2 defines a glass which, due to the higher K ₂ O content, will be well clarified, processed and discolored. The glass according to the embodiment 3 is a low melting type of glass with a high refractive index corresponding to the best quality lead crystal glasses.

Table 5: Composition of exemplary glasses according to the invention in% by weight and their parameters determined

Oxide / Example 1 2 3 SiO ₂ 67,066 63,173 59,125 LijO 0.850 0.541 2,149 Na ₂ O 8,199 2,797 11,397 K ₂ O 4,802 15,406 3,490 CaO 8,202 8,503 7,188 ZnO 2,401 2,005 7,711 B ₂ O ₃ 2,900 2,008 3,071 ai ₂ o ₃ 2,499 2,481 0.430 TiO ₂ 2,040 1,941 2,082 ZrO ₂ - - 2,082 Gd ₂ O ₃ 0.100 0,102 0,103 P ₂ O ₅ 0.401 0.503 0.701 Sb ₂ O ₃ 0.540 0.540 0.471 Detected parameters Index to n _D 1,5302 1.5319 1,5624 Density [g / cm ³ 1 2.5434 2.5516 2.7058 Young's modulus E [GPa] 113.333 99.190 116.339 Melting point / logn-2 / [“C J 1374 1376 1147 Processing temperature / log η = 4 / [’C] 986 1005 855 Softening point / logq = 7.65 / [° C] 706 733 637 Liquid temperature [° C] 959 956 850 Maximum crystallization rate temperature [’C] 859 886 791 Maximum crystallization rate [pm / min] 1,235 0,633 0,122 Hydrolytic resistance [ml of HCl [C = 0.01 mol / L] 0.26 0.61 0.36

-7EN 302723 B6

Industrial use

The crystal glass according to the invention is intended for the production of costume jewelery and chandelier blanks and their products, production of glass chandeliers and household articles.

It is, of course, possible to use it elsewhere where it is appropriate due to its properties.

Claims (8)

PATENT CLAIMS 1. Crystal glass having a refractive index exceeding 1,53, free of lead, barium and arsenic compounds, characterized in that it consists of 55 to 70% SiO ₂ , 20 0.05 to 3.5% Li ₂ O, 2 to 15% Na ₂ O, more than 3% and less than 5% or more than 15% and less than 19% of K ₂ O, 5 to 10% CaO, more than 1% and less than 4% or more than 7% and less than 8% ZnO,?> OJ to 3,5% B ₂ O ₃ , OJ up to 3.5% Al ₂ C% OJ up to 3,5% TiO ₂ , less than 3,5% ZrO ₂ , 0.05 to 1.5% Gd ₂ O ₃ , 0.05 to 1% P ₂ O ₅ , OJ to I% Sb ₂ O ₃ . Crystal glass according to claim 1, characterized in that it contains from 0.05 to 0.8% Gd ₂ Oi and from 0.05 to 0.8% P1O5 with a Gd ₂ O ₃ / P ₂ O ₅ ratio of at least 1% by weight. : l. Crystal glass according to claim 1, characterized in that it comprises by weight 0.05 to OJ 5% Gd ₂ O ₂ and OJ to 0.8% P2O 5 at a ratio of Gd ₂ O 3 / P ₂ O _{5 of} at least 1: 2. Crystal glass according to claim 1, characterized in that it comprises by weight 40 0.1% Gd ₂ Ch and 0.2 to 0.8% P ₂ O ₅ with a Gd ₂ OVP ₂ O ₅ ratio of at least 1: 2. Crystal glass according to claim 1, characterized in that it is clarified and discolored with the usual clarifying and bleaching components and / or mixtures thereof in the usual concentrations. Crystal glass according to claim 1, characterized in that it consists of 67.066% SiO ₂ , 0.850% Li ₂ O, 50 8.199% Na ₂ O, 4.802% K ₂ O, 8.202% CaO, 2,401% ZnO, 2,499% Al ₂ O ₃ , 2,900% b ₂ o ₃ , 2,040% tío ₂ , 0.100% Gd ₂ O ₃ 0.401% BYE, 0.540% Sb ₂ O ₃ . Crystal glass according to claim 1, characterized in that it consists of 63.173% SiO ₂ , 0.541% Li ₂ O, 2,797% Na ₂ O, 15.406% K ₂ O, 8.503% CaO, 2,005% ZnO, 2.471% A1 ₂ O ₃ , 2.008% B ₂ O ₃ , I 941% TiO _2, 0.102% Gd ₂ O ₃ , 0.503% P ₂ O ₅ , 0.540% Sb ₂ O ₃ . Crystal glass according to claim 1, characterized in that it consists of 59.125% SiO ₂ , 2.149% Li ₂ O, II 397% Na ₂ O, 3,490% K ₂ O, 7.188% CaO, 7.711% ZnO, 0.430% Al ₂ O ₃ , 3,071% B ₂ O ₃ 2.082% TiO ₂ , 2,082% ZrO ₂ , 0.103% Gd ₂ O ₃ , 0.701% P ₂ O ₅ 0.471% Sb ₂ O ₃ .