Halide glass and optical element

Abstract

Provided are halide glass comparable in dispersion characteristics to fluorite and an optical element. The halide glass contains, in terms of mol percent, 11%-40% of AlF3, 0.1%-20% of ScF3, and 10%-88.9% of MgF2+CaF2+SHg2+BaF2.

Description

Halide glasses and optical elements

[0001] The present invention relates to halide glasses and optical elements.

[0002] In optical systems such as cameras, lenses made of low-dispersion materials are used to correct chromatic aberration. For example, fluorite is known as a typical low-dispersion material.

[0003] On the other hand, fluorite is poor in formability and processability, and lens manufacturing requires a lot of time and cost. Therefore, as an alternative material to fluorite, for example, fluoride glass and halide glass such as fluorophosphate glass, which have an Abbe number (νd) similar to that of fluorite, have been investigated (Patent Documents 1 and 2).

[0004] JP 2019-151493 A JP 2016-023111 A

[0005] In addition to its low dispersion, fluorite also exhibits a high partial dispersion ratio (anomalous partial dispersion). Therefore, halide glasses with dispersion properties comparable to those of fluorite have not yet been developed, and further research is needed.

[0006] In view of the above, an object of the present invention is to provide a halide glass and an optical element having dispersion characteristics comparable to those of fluorite.

[0007] Various aspects of halide glasses and optical elements that solve the above problems will now be described.

[0008] The halide glass of embodiment 1 contains, in mole percent, AlF ３ 11-40%, ScF ３ 0.1-20%, MgF ２ +CaF ２ + SrF ２ +BaF ２ It is characterized by containing 10 to 88.9%.

[0009] The halide glass of embodiment 2 is the same as embodiment 1, but further containing, in mol %, MgF ２ 0-30%, CaF ２ 0-30%, SrF ２ 0-30%, BaF ２ It is preferable that the content is 0 to 20%.

[0010] The halide glass of embodiment 3 is the same as embodiment 1 or embodiment 2, further comprising, in mol %, YF ３ It is preferable that the content is 0 to 20%.

[0011] The halide glass of embodiment 4 is any one of embodiments 1 to 3, and is a glass containing, in a molar ratio, ScF ３ / (AlF ３ +YF ３ +ScF ３ ) is preferably 0.01 to 0.5.

[0012] The halide glass of embodiment 5 contains, in cation %, Al ３＋ 11-60%, Sc ３＋ 0.1-20%, Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ 10 to 88.9%, and in anion %, F － It is characterized by containing 70 to 100%.

[0013] The halide glass of embodiment 6 is the same as embodiment 5, further comprising, in anion %: Cl － +Br － +I － The content is preferably 0 to 10%.

[0014] The halide glass of embodiment 7 is the same as embodiment 5 or 6, further comprising, in cation %, Mg ２＋ 0-30%, Ca ２＋ 0-30%, Sr ２＋ 0-30%, Ba ２＋ It is preferable that the content is 0 to 20%.

[0015] The halide glass of Aspect 8 is any one of Aspects 5 to 7, further comprising, in cation %, Y ３＋ It is preferable that the content is 0 to 20%.

[0016] The halide glass of Aspect 9 is preferably any one of Aspects 5 to 8, further containing, in cation %, less than 0.01% of Ln (Ln is at least one selected from Cr, Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm).

[0017] The halide glass of Aspect 10 is any one of Aspects 1 to 9, and preferably has an Abbe number (νd) of 85 to 110.

[0018] The halide glass of embodiment 11 is any one of embodiments 1 to 10, and preferably has a partial dispersion ratio (θg,F) of 0.516 to 0.580.

[0019] The optical element of Aspect 12 is characterized in that it is made of the halide glass of any one of Aspects 1 to 11.

[0020] According to the present invention, it is possible to provide halide glass and optical elements having dispersion characteristics comparable to those of fluorite.

[0021] (Halide Glass A) In some embodiments of the present invention, the halide glass comprises, in mole percent, AlF ３ 11-40%, ScF ３ 0.1-20%, MgF ２ +CaF ２ + SrF ２ +BaF ２ The halide glass A is characterized by containing 10 to 88.9% of each component. The reasons for limiting the content of each component as described above are as follows. In the explanation of the content of each component of the halide glass A, % denotes mol % unless otherwise specified.

[0022] AlF ３ is an essential component that can increase stability against crystallization. ３ The content of AlF is preferably 11 to 40%. ３ The lower limit of the content of AlF is preferably 11% or more, 12% or more, 15% or more, 20% or more, and particularly preferably 25% or more. ３The upper limit of the AlF content is preferably 40% or less, 35% or less, and particularly preferably 33% or less. ３ If the content of AlF is too low, crystallization occurs easily. ３ If the content is too large, the partial dispersion ratio (θg,F) tends to decrease.

[0023] ScF ３ is an essential component that is particularly likely to increase the partial dispersion ratio (θg,F). ３ The content of ScF is preferably 0.1 to 20%. ３ The lower limit of the content of ScF is preferably 0.1% or more, 1% or more, 1.5% or more, 2% or more, and particularly preferably 5% or more. ３ The upper limit of the content of ScF is preferably 20% or less, and particularly preferably 19% or less. ３ If the content of ScF is too small, the partial dispersion ratio (θg,F) tends to decrease. ３ If the content is too high, crystallization will occur easily.

[0024] MgF ２ , CaF ２ , SrF ２ and BaF ２ is a component that tends to increase the stability of glass. ２ +CaF ２ + SrF ２ +BaF ２ The content of MgF is preferably 10 to 88.9%. ２ +CaF ２ + SrF ２ +BaF ２ The lower limit of the content of MgF is preferably 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, and particularly preferably 45% or more. ２ +CaF ２ + SrF ２ +BaF ２ The upper limit of the content of MgF is preferably 88.9% or less, 88.8% or less, 80% or less, 75% or less, 70% or less, 65% or less, or 60% or less, particularly preferably 57.5% or less. ２ +CaF ２ + SrF ２ +BaF ２If the content of MgF is too low, it becomes difficult to obtain the above effects. ２ +CaF ２ + SrF ２ +BaF ２ If the content of "MgF" is too high, the partial dispersion ratio (θg,F) tends to be low. ２ +CaF ２ + SrF ２ +BaF ２ " is MgF ２ , CaF ２ , SrF ２ and BaF ２ Also, MgF ２ , CaF ２ , SrF ２ and BaF ２ The preferred content of each component is as follows:

[0025] MgF ２ is a component that reduces dispersibility. ２ The content of MgF is preferably 0 to 30%. ２ The lower limit of the content of MgF is preferably 0% or more, 1% or more, 5% or more, 10% or more, and particularly preferably 15% or more. ２ The upper limit of the content of MgF is preferably 30% or less, 28% or less, 26% or less, and particularly preferably 24% or less. ２ If the content is too high, crystallization will occur easily.

[0026] CaF ２ is a component that tends to increase the stability of the glass. ２ The content of CaF is preferably 0 to 30%. ２ The lower limit of the content of CaF is preferably 0% or more, 1% or more, 5% or more, 8% or more, and particularly preferably 10% or more. ２ The upper limit of the content of CaF is preferably 30% or less, 27% or less, 25% or less, 22% or less, and particularly preferably 20% or less. ２ If the content is too high, the Abbe number (νd) tends to be high, and the partial dispersion ratio (θg, F) ​​tends to be low.

[0027] SrF ２ is a component that enhances stability against vitrification.２ The content of SrF is preferably 0 to 30%. ２ The lower limit of the content of SrF is preferably 0% or more, 1% or more, 5% or more, 8% or more, and particularly preferably 10% or more. ２ The upper limit of the content of SrF is preferably 30% or less, 29% or less, 27% or less, 25% or less, 23% or less, and particularly preferably 20% or less. ２ If the content is too high, crystallization will occur easily.

[0028] BaF ２ is a component that increases stability against crystallization and tends to increase the Abbe number (νd). ２ The content of BaF is preferably 0 to 20%. ２ The lower limit of the content of BaF is preferably 0% or more, 1% or more, 3% or more, and particularly preferably 5% or more. ２ The upper limit of the content of BaF is preferably 20% or less, and particularly preferably 17% or less. ２ If the content is too large, the partial dispersion ratio (θg,F) tends to decrease.

[0029] YF ３ is a component that can increase stability against crystallization. ３ The content of is preferably 0 to 20%. ３ The lower limit of the content of YF is preferably 0% or more, 0.1% or more, 1% or more, and particularly preferably 3% or more. ３ The upper limit of the content of YF is preferably 20% or less, 19% or less, 15% or less, 13% or less, and particularly preferably 11% or less. ３ If the content is too small, the partial dispersion ratio (θg,F) tends to decrease, and if it is too large, crystallization tends to occur.

[0030] Molar ratio ScF ３ / (AlF ３ +YF ３ +ScF ３ ) is preferably 0.01 to 0.5. More specifically, ScF ３ / (AlF ３ +YF ３ +ScF ３ The upper limit of ScF is preferably 0.5 or less, 0.4 or less, and particularly preferably 0.3 or less.３ / (AlF ３ +YF ３ +ScF ３ The lower limit of ScF is preferably 0.01 or more, and particularly preferably 0.1 or more. By satisfying the above value, it becomes easier to increase the Abbe number (νd). ３ / (AlF ３ +YF ３ +ScF ３ ) is ScF ３ The content of AlF ３ , Y.F. ３ and ScF ３ It refers to the value divided by the total amount of

[0031] The halide glass of the present invention may further contain other fluoride components, for example, ZrF ４ , HfF ４ , GaF ３ , InF ３ , ZnF ２ More specifically, ZrF ４ , HfF ４ , GaF ３ , InF ３ , ZnF ２ may be contained in a total amount of 15% or less, 10% or less, particularly 5% or less.

[0032] The halide glass of the present invention is preferably a so-called fluoride glass containing fluoride as a main component, although the halide glass of the present invention may contain the following optional components in addition to fluoride.

[0033] The halide glass of the present invention is AlCl ３ , YCl ３ , LaCl ３ , GdCl ３ , YbCl ３ , MgCl ２ , CaCl ２ , SrCl ２ , BaCl ２It is preferable to contain chloride components such as BaCl. By containing chloride components, the stability of the glass is easily improved. More specifically, the upper limit of the total amount of chloride components is preferably 15% or less, 10% or less, particularly 5% or less. The lower limit of the total amount of chloride components is preferably, for example, 0% or more, 0.1% or more, particularly 0.5% or more. Furthermore, the content of each chloride component is preferably 15% or less, 10% or less, particularly 5% or less, and the lower limit of the content of each component may be, for example, 0% or more, 0.1% or more, particularly 0.5% or more. Among the above chloride components, BaCl is particularly preferable from the viewpoint of raw material costs. ２ For example, BaCl ２ It is preferable that the content is 0 to 15%, 0 to 10%, and particularly 0.1 to 10%.

[0034] The halide glass of the present invention contains Al(PO ３ ) ３ , Mg(PO ３ ) ２ , Ca(PO ３ ) ２ , Sr(PO ３ ) ２ , Ba(PO ３ ) ２ , P ２ O ５ , KPF ６ It is preferable that the glass contains a phosphate component such as phosphate. The inclusion of a phosphate component can enhance the stability of the glass. From the viewpoint of accurately enjoying the effects of the present invention, the content of the phosphate components is preferably 15% or less, 10% or less, and particularly 5% or less in total. The lower limit of the total content of the phosphate components may be, for example, 0% or more, 0.1% or more, and particularly 0.5% or more.

[0035] (Halide Glass B) In one embodiment of the present invention, the halide glass contains, in cation %, Al ３＋ 11-60%, Sc ３＋ 0.1-20%, Mg ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ 10 to 88.9%, and in anion %, F －The halide glass B is characterized by containing 70 to 100% of each component. The reasons for limiting the content of each component as described above are as follows. In the explanation of the content of each component of the halide glass B, the percentage indicates cation % or anion % unless otherwise specified.

[0036] Al ３＋ is an essential component that can increase stability against crystallization. ３＋ The content of Al is preferably 11 to 60%. ３＋ The lower limit of the Al content is preferably 11% or more, 12% or more, 15% or more, 20% or more, and particularly preferably 25% or more. ３＋ The upper limit of the Al content is preferably 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, particularly preferably 33% or less. ３＋ If the content of Al is too low, crystallization occurs easily. ３＋ If the content is too large, the partial dispersion ratio (θg,F) tends to decrease.

[0037] Sc ３＋ is an essential component that is particularly likely to increase the partial dispersion ratio (θg, F). ３＋ The content of Sc is preferably 0.1 to 20%. ３＋ The lower limit of the content of Sc is preferably 0.1% or more, 1% or more, 1.5% or more, 2% or more, particularly preferably 5% or more. ３＋ The upper limit of the content of Sc is preferably 20% or less, particularly preferably 19% or less. ３＋ If the content of Sc is too small, the partial dispersion ratio (θg, F) ​​tends to decrease. ３＋ If the content is too high, crystallization will occur easily.

[0038] Mg ２＋ , Ca ２＋ , Sr ２＋ and Ba ２＋ is a component that tends to increase the stability of glass. ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ The content of Mg is preferably 10 to 88.9%. ２＋ + Ca ２＋ + Sr２＋ +Ba ２＋ The lower limit of the Mg content is preferably 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, and particularly preferably 45% or more. ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ The upper limit of the Mg content is preferably 88.9% or less, 88.8% or less, 80% or less, 75% or less, 70% or less, 65% or less, or 60% or less, particularly preferably 57.5% or less. ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ If the content is too low, it becomes difficult to obtain the above effects. ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ If the content of "Mg" is too high, the partial dispersion ratio (θg,F) tends to be low. ２＋ + Ca ２＋ + Sr ２＋ +Ba ２＋ " is Mg ２＋ , Ca ２＋ , Sr ２＋ and Ba ２＋ Also, Mg ２＋ , Ca ２＋ , Sr ２＋ and Ba ２＋ The preferred content of each component is as follows:

[0039] Mg ２＋ is a component that reduces dispersibility. ２＋ The content of Mg is preferably 0 to 30%. ２＋ The lower limit of the Mg content is preferably 0% or more, 1% or more, 5% or more, 10% or more, and particularly preferably 15% or more. ２＋ The upper limit of the Mg content is preferably 30% or less, 28% or less, 26% or less, and particularly preferably 24% or less. ２＋ If the content is too high, crystallization will occur easily.

[0040] Ca ２＋ is a component that tends to increase the stability of the glass. ２＋The content of Ca is preferably 0 to 30%. ２＋ The lower limit of the content of Ca is preferably 0% or more, 1% or more, 5% or more, 8% or more, and particularly preferably 10% or more. ２＋ The upper limit of the content of Ca is preferably 30% or less, 27% or less, 25% or less, 22% or less, particularly preferably 20% or less. ２＋ If the content is too high, the Abbe number (νd) tends to be high, and the partial dispersion ratio (θg, F) ​​tends to be low.

[0041] Sr ２＋ is a component that enhances stability against vitrification. ２＋ The content of Sr is preferably 0 to 30%. ２＋ The lower limit of the Sr content is preferably 0% or more, 1% or more, 5% or more, 8% or more, and particularly preferably 10% or more. ２＋ The upper limit of the Sr content is preferably 30% or less, 29% or less, 27% or less, 25% or less, 23% or less, and particularly preferably 20% or less. ２＋ If the content is too high, crystallization will occur easily.

[0042] Ba ２＋ is a component that increases stability against crystallization and tends to increase the Abbe number (νd). ２＋ The content of Ba is preferably 0 to 20%. ２＋ The lower limit of the content of Ba is preferably 0% or more, 1% or more, 3% or more, and particularly preferably 5% or more. ２＋ The upper limit of the content of Ba is preferably 20% or less, and particularly preferably 17% or less. ２＋ If the content is too large, the partial dispersion ratio (θg,F) tends to decrease.

[0043] Y ３＋ is a component that can increase stability against crystallization. ３＋ The content of Y is preferably 0 to 20%. ３＋ The lower limit of the content of Y is preferably 0% or more, 0.1% or more, 1% or more, and particularly preferably 3% or more. ３＋ The upper limit of the content of Y is preferably 20% or less, 19% or less, 15% or less, 13% or less, and particularly preferably 11% or less. ３＋If the content is too small, the partial dispersion ratio (θg,F) tends to decrease, and if it is too large, crystallization tends to occur.

[0044] Cation ratio Sc ３＋ / (Al ３＋ +Y ３＋ +Sc ３＋ ) is preferably 0.01 to 0.5. ３＋ / (Al ３＋ +Y ３＋ +Sc ３＋ The upper limit of Sc is preferably 0.5 or less, and particularly preferably 0.3 or less. ３＋ / (Al ３＋ +Y ３＋ +Sc ３＋ The lower limit of Sc is preferably 0.01 or more, particularly preferably 0.1 or more. By satisfying the above value, it becomes easier to increase the Abbe number (νd). ３＋ / (Al ３＋ +Y ３＋ +Sc ３＋ ) is Sc ３＋ The content of Al ３＋ , Y ３＋ and Sc ３＋ It refers to the value divided by the total amount of

[0045] The halide glass of the present invention may further contain other cation components. For example, Zr ４＋ , Hf ４＋ , Ga ３＋ , In ３＋ and Zn ２＋ For example, Zr ４＋ , Hf ４＋ , Ga ３＋ , In ３＋ and Zn ２＋ may be contained in a total amount of 15% or less, 10% or less, particularly 5% or less.

[0046] The halide glass of the present invention preferably contains less than 0.01%, less than 0.001%, or even no Ln (Ln is at least one element selected from Cr, Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm). If the content of these elements is high, the glass is prone to devitrification. Furthermore, coloring may occur in the halide glass, making it difficult to use it as a substitute for fluorite. The valence of Cr is preferably trivalent (Cr ３＋ ), hexavalent (Cr ６＋ ) is an example of, but not limited to, Ce. The valence of Ce is trivalent (Ce ３＋ ), tetravalent (Ce ４＋ ) is an example of, but not limited to, Nd. The valence of Nd is trivalent (Nd ３＋ ) is an example, but is not limited to this. The valence of Yb is trivalent (Yb ３＋ ) is an example of, but not limited to, Er. The valence of Er is trivalent (Er ３＋ ) is an example of, but not limited to, Pr. The valence of Pr is trivalent (Pr ３＋ ) is an example of, but not limited to, Sm. The valence of Sm is trivalent (Sm ３＋ ) is an example, but is not limited to this. The valence of Eu is trivalent (Eu ３＋ ) is an example of, but not limited to, Tb. The valence of Tb is trivalent (Tb ３＋ ), tetravalent (Tb ４＋ ) is an example of, but not limited to, Dy. The valence of Dy is trivalent (Dy ３＋ ) is an example, but is not limited to this. The valence of Ho is trivalent (Ho ３＋ ) is an example, but is not limited to this. The valence of Tm is trivalent (Tm ３＋ ) are examples, but are not limited to these.

[0047] F － is an essential component for forming the halide glass of the present invention. － The content of F is preferably 70 to 100%. － The lower limit of the content of F is preferably 70% or more, 80% or more, 90% or more, and particularly preferably 95% or more. － If the content of F is too low, vitrification becomes difficult.－ The upper limit of the content of F is preferably 100% or less, 99.9% or less, and particularly preferably 99.6% or less. － In order to contain an anion component other than F － The upper limit of the content may be set to 95% or less, particularly 90% or less.

[0048] The halide glass of the present invention may contain the following anion components:

[0049] Cl － ,Br － and I － is F － It is a component that improves stability against crystallization when it coexists with Cl in glass. － +Br － +I － The content of Cl is preferably 0 to 10%. － +Br － +I － The lower limit of the Cl content is preferably 0% or more, 0.1% or more, 0.2% or more, and particularly preferably 0.3% or more. － +Br － +I － The upper limit of the Cl content is preferably 10% or less, 6% or less, 5% or less, and particularly preferably 3% or less. － +Br － +I － If the content of "Cl" is too high, problems such as devitrification of the glass, phase separation of the glass, and deterioration of weather resistance are likely to occur. － +Br － +I － " is Cl － ,Br － and I － The total amount of

[0050] Cl － is F － It is a component that, when present together with Cl in glass, tends to significantly improve stability against crystallization. － The content of Cl is preferably 0 to 10%. － The lower limit of the Cl content is preferably 0% or more, 0.1% or more, 0.2% or more, and particularly preferably 0.3% or more. －The upper limit of the Cl content is preferably 10% or less, 6% or less, 5% or less, and particularly preferably 3% or less. － If the content is too high, problems such as devitrification of the glass, phase separation of the glass, and deterioration of weather resistance are likely to occur.

[0051] Br － is F － It is a component that, when present together with Br in glass, tends to improve stability against crystallization. － The content of Br is preferably 0 to 10%. － The lower limit of the content of Br is preferably 0% or more, 0.1% or more, 0.2% or more, particularly preferably 0.3% or more. － The upper limit of the content of Br is preferably 10% or less, 6% or less, 5% or less, and particularly preferably 3% or less. － If the content is too high, problems such as devitrification of the glass, phase separation of the glass, and deterioration of weather resistance are likely to occur.

[0052] I － is F － It is a component that, when present together with SiO2 in glass, tends to improve stability against crystallization. － The content of is preferably 0 to 10%. － The lower limit of the content of I is preferably 0% or more, 0.1% or more, 0.2% or more, and particularly preferably 0.3% or more. － The upper limit of the content is preferably 10% or less, 6% or less, 5% or less, and particularly preferably 3% or less. － If the content is too high, problems such as devitrification of the glass, phase separation of the glass, and deterioration of weather resistance are likely to occur.

[0053] By satisfying the above composition, the halide glasses A and B of the present invention can have dispersion characteristics comparable to those of fluorite. For example, the halide glasses of the present invention preferably have an Abbe number (νd) of 85 to 110 and a partial dispersion ratio (θg,F) of 0.515 to 0.550.

[0054] The Abbe number (νd) is preferably 85 to 110. More specifically, the lower limit of the Abbe number (νd) is preferably 85 or more, 90 or more, 91 or more, or 93 or more, and particularly preferably 95 or more. The upper limit of the Abbe number (νd) is preferably 110 or less, 100 or less, and particularly preferably 99 or less. By having the above Abbe number (νd), the halide glass of the present invention can be suitably used as a substitute for fluorite.

[0055] The partial dispersion ratio (θg, F) ​​is preferably 0.516 to 0.580. More specifically, the lower limit of the partial dispersion ratio (θg, F) ​​is preferably 0.516 or more, 0.520 or more, 0.525 or more, and particularly preferably 0.530 or more. The upper limit of the partial dispersion ratio (θg, F) ​​is preferably 0.580 or less, 0.550 or less, and particularly preferably 0.545 or less. By having the above partial dispersion ratio (θg, F), the halide glass of the present invention exhibits anomalous partial dispersion comparable to that of fluorite. Therefore, it can be suitably used as a substitute for fluorite.

[0056] The halide glass of the present invention preferably has a refractive index (nd) of 1.39 to 1.5, particularly 1.40 to 1.45. By having this refractive index, the halide glass of the present invention is comparable to fluorite in terms of refractive index and can be suitably used as a substitute for fluorite.

[0057] The halide glass of the present invention can be suitably used as an optical element. In other words, the optical element of the present invention is characterized by comprising the above-mentioned halide glass of the present invention. Examples of optical elements include optical lenses, prisms, filters, diffraction gratings, optical fibers, etc., and optical lenses are particularly preferred. The optical lens is preferably a special low-dispersion lens.

[0058] The halide glass of the present invention can be produced, for example, as follows.

[0059] First, raw materials are weighed to obtain a raw material batch having the desired composition. Then, the raw material batch is placed in a crucible. The crucible may be a platinum crucible, a gold crucible, a glassy carbon crucible, or the like.

[0060] Next, the raw material batch is melted at approximately 900°C to 1100°C. The melting time can be, for example, 1 to 2 hours. The melt is then rapidly cooled and gradually strained near the glass transition temperature to obtain a halide glass.

[0061] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0062] Tables 1 to 10 show Examples 1 to 95 of the present invention and Comparative Example 1.

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073] The samples were prepared by the following procedure. First, raw materials were weighed to obtain a raw material batch having the composition shown in Tables 1 to 10. Next, the raw material batch was placed in a crucible and melted at 900°C to 1100°C, and the melt was then rapidly cooled to obtain a sample. The refractive index of the obtained sample was measured, and the Abbe number (νd) and partial dispersion ratio (θg, F) ​​were determined. The results of the refractive index (nd), Abbe number (νd), and partial dispersion ratio (θg, F) ​​are shown in Tables 1 to 10.

[0074] The refractive index was measured by the well-known V-block method using a Kalnew precision refractometer (Shimadzu Corporation, KPR-2000).

[0075] The Abbe number (νd) and the partial dispersion ratio (θg,F) were calculated from the following formula using the measured refractive indexes nd (587.56 nm), nC (656.27 nm), nF (486.07 nm), and ng (435.83 nm).

[0076] νd=(nd-1) / (nF-nC)

[0077] θg,F=(ng-nF) / (nF-nC)

[0078] As shown in Tables 1 to 10, Examples 1 to 95 had a refractive index (nd) of 1.41 or more, an Abbe number (νd) of 85 or more, and a partial dispersion ratio (θg, F) ​​of 0.516 or more. On the other hand, Comparative Example 1 had a partial dispersion ratio (θg, F) ​​of less than 0.516.

[0079] The halide glass of the present invention can be suitably used as optical elements such as lenses, prisms, filters, diffraction gratings, optical fibers, etc. In particular, it can be suitably used as a special low dispersion lens.

Claims

1. AlF in mole percent ３ 11-40%, ScF ３ 0.1-20%, MgF ２ +CaF ２ + SrF ２ +BaF ２ A halide glass containing 10 to 88.9%.

2. In addition, MgF ２ 0-30%, CaF ２ 0-30%, SrF ２ 0-30%, BaF ２ 2. The halide glass according to claim 1, containing 0 to 20%.

3. In addition, YF ３ 3. The halide glass according to claim 1, containing 0 to 20%.

4. Molar ratio: ScF ３ / (AlF ３ +YF ３ +ScF ３ 3. The halide glass according to claim 1, wherein n is 0.01 to 0.

5.

5. Cation % Al ３＋ 11-60%, Sc ３＋ 0.1-20%, Mg ２＋ +Ca ２＋ + Sr ２＋ +Ba ２＋ 10 to 88.9%, and the anion content is F － A halide glass containing 70 to 100%.

6. In addition, the anion percentage is Cl. － +Br － +I － The halide glass according to claim 5, containing 0 to 10%.

7. In addition, the cation percentage is Mg ２＋ 0-30%, Ca ２＋ 0-30%, Sr ２＋ 0-30%, Ba ２＋ 7. The halide glass according to claim 5, containing 0 to 20%.

8. In addition, the cationic percentage is Y. ３＋ 7. The halide glass according to claim 5, containing 0 to 20%.

9. The halide glass according to claim 5 or 6, further containing, in cation percentage, less than 0.01% of Ln (Ln is at least one selected from Cr, Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho and Tm).

10. The halide glass according to claim 1 or 5, having an Abbe number (νd) of 85 to 110.

11. The halide glass according to claim 1 or 5, wherein the partial dispersion ratio (θg,F) is 0.516 to 0.

580.

12. An optical element comprising the halide glass according to claim 1 or 5.