JP2006206421A - Crystallized glass and device for optical communications using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide crystallized glass which is easily formable and high in bending strength and a device for optical communications using the same. <P>SOLUTION: The crystallized glass comprises a main crystal composed of a β-quartz solid solution or a β-eucryptite solid solution, has -16×10<SP>-7</SP>-(-45×10<SP>-7</SP>)/°C average thermal expansion coefficient at -40 to 100°C, contains 0.5-2.9% by mass in total of TiO<SB>2</SB>, ZrO<SB>2</SB>and P<SB>2</SB>O<SB>5</SB>where the molar ratio (Li<SB>2</SB>O+ZnO)/SiO<SB>2</SB>is 0.15-0.35. The device for optical communications is the crystallized glass comprising a main crystal composed of a β-quartz solid solution or a β-eucryptite solid solution, having -16×10<SP>-7</SP>-(-45×10<SP>-7</SP>)/°C average thermal expansion coefficient at -40 to 100°C and containing 0.5-2.9% by mass in total of TiO<SB>2</SB>, ZrO<SB>2</SB>and P<SB>2</SB>O<SB>5</SB>where the molar ratio (Li<SB>2</SB>O+ZnO)/SiO<SB>2</SB>is 0.15-0.35 is used for a member for compensating temperature. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a crystallized glass in which a β-quartz solid solution or a β-eucryptite solid solution is precipitated as a main crystal, and an optical communication device using the same.

  In recent years, with the development of optical communication technology, networks using optical fibers are being rapidly developed. In such a network, a wavelength multiplexing technique that transmits light of a plurality of wavelengths at once is used, and wavelength filters, couplers, waveguides, and the like are used as important optical communication devices.

  Some of these optical communication devices have characteristics that change depending on the temperature and interfere with outdoor use. Therefore, technology to maintain the characteristics of such optical communication devices constant regardless of temperature changes. What is called temperature compensation technology is needed.

  A typical optical communication device that requires temperature compensation technology is a fiber Bragg grating (hereinafter referred to as FBG). The FBG is a device for optical communication in which a portion having a refractive index change in a lattice shape in a core of an optical fiber, that is, a so-called grating portion is formed, and has a characteristic of reflecting light of a specific wavelength. Therefore, it is important as an optical communication device capable of separating only a specific wavelength in an optical communication system of a wavelength division multiplex transmission system in which optical signals having different wavelengths are multiplexed and transmitted through a single optical fiber.

  The FBG has a problem that the reflection wavelength fluctuates because the lattice spacing and refractive index of the grating portion change when the temperature changes. In order to reduce such fluctuations in the reflected wavelength, the lattice spacing and refractive index can be reduced by fixing the FBG to a base material made of a material having a negative coefficient of thermal expansion and applying a tension according to the temperature change to the FBG. There is a known method for reducing the change in. (For example, refer to Patent Document 1).

  In addition to the above-described FBG, there is an optical waveguide device as an optical communication device that requires temperature compensation technology. Typical examples include an arrayed waveguide (hereinafter referred to as AWG) and a planar optical circuit (hereinafter referred to as PLC). There is. An AWG or PLC is a device that has a waveguide layer on a planar substrate, a core and a cladding are formed in the waveguide layer, and can perform processing such as light branching, multiplexing, and demultiplexing.

  However, such an optical waveguide device has a problem that the time required for light to pass varies because the optical path length of the waveguide changes as the temperature changes. In order to reduce such fluctuations in the passage time of light, it is known that the change in the optical path length of the waveguide can be reduced by using a material having a negative thermal expansion coefficient for the substrate (for example, Patent Document 2). reference.).

Moreover, crystallized glass in which β-quartz solid solution or β-eucryptite solid solution is precipitated as a main crystal is known as a material having the above negative thermal expansion coefficient (for example, see Patent Documents 1 and 2).
Special Table 2000-503967 JP 2003-20254 A

  In the crystallized glass disclosed in Patent Document 1, crystals having anisotropy in thermal expansion are precipitated, and a large number of voids and cracks exist at the crystal grain boundaries. Therefore, the positive thermal expansion component of the crystal is relaxed by voids and cracks, and the contribution of the negative thermal expansion component is increased, and this crystallized glass has a negative thermal expansion coefficient as a whole. However, this crystallized glass has a problem that bending strength is low because there are many voids and cracks in the crystal grain boundary.

  In addition, the crystallized glass disclosed in Patent Document 2 is a crystal of β-quartz solid solution or β-eucryptite solid solution having no negative thermal expansion coefficient in the glass matrix, although there are no voids or cracks in the crystal grain boundaries. By precipitating in a large amount, the thermal expansion behavior of the crystal is reflected to have a negative thermal expansion coefficient. However, this crystallized glass has a problem that although there are no voids or cracks in the crystal grain boundary, the crystal grain size is small, so the bending strength is low, and it is easy to be devitrified, so it is difficult to form into a desired shape. .

  An object of the present invention is to provide a crystallized glass that is easy to mold and has high bending strength, and a device for optical communication using the same.

  As a result of various investigations, the present inventors have found that the inclusion of an appropriate amount of a nucleating agent makes the crystallized glass have a high bending strength and is easy to mold, leading to the present invention. .

That is, the crystallized glass of the present invention precipitates β-quartz solid solution or β-eucryptite solid solution as a main crystal, and has an average coefficient of thermal expansion at −40 ° C. to 100 ° C. of −16 to −45 × 10 ⁻⁷ / The crystallized glass at 0 ° C., and the total amount of TiO ₂ , ZrO ₂ and P ₂ O ₅ is 0.5 to 2.9% by mass, and the molar ratio (Li ₂ O + ZnO) / SiO ₂ is 0 .15 to 0.35.

Moreover, the device for optical communication of the present invention precipitates β-quartz solid solution or β-eucryptite solid solution as a main crystal, and has an average thermal expansion coefficient of −16 to −45 × 10 ^{−7 at} −40 ° C. to 100 ° C. Is a crystallized glass having a molar ratio (Li ₂ O + ZnO) / SiO _{2 of} 0.5 to 2.9% by mass%, and the total amount of TiO ₂ , ZrO ₂ and P ₂ O ₅ is% by mass. It is characterized by using crystallized glass of 0.15 to 0.35 as a member for temperature compensation.

The crystallized glass of the present invention precipitates β-quartz solid solution or β-eucryptite solid solution as a main crystal, and has an average thermal expansion coefficient of −16 to −45 × 10 ⁻⁷ / ° C. at −40 ° C. to 100 ° C. Therefore, it can be used as a temperature compensating member, particularly as a temperature compensating member for an optical communication device.

Further, since the total amount of TiO ₂ , ZrO ₂ and P ₂ O ₅ by mass% is 0.5 to 2.9%, the liquidus temperature becomes low, it is difficult to be devitrified, and it is easy to mold and bend. High strength.

That is, since the total amount of TiO ₂ , ZrO ₂ and P ₂ O ₅ that are nucleating agents is 0.5 to 2.9% by mass, the liquidus temperature becomes low and the glass is devitrified when it is molded. It becomes difficult. Moreover, TiO ₂ , ZrO _2, and P ₂ O _{5 which} are nucleating agents become crystal nuclei, but since the content thereof is small, the crystal grain size becomes larger than the case where the content of nucleating agent is large. , Bending strength is increased.

Furthermore, since the molar ratio (Li ₂ O + ZnO) / SiO ₂ is 0.15 to 0.35, the degree of crystallinity is high, and there are substantially no voids or cracks at the grain boundaries, and at −40 to 100 ° C. The average thermal expansion coefficient tends to be −16 to −45 × 10 ⁻⁷ / ° C. Since there are substantially no voids or cracks in the crystal grain boundary, it can be processed to a thickness of submicron, optical polishing is possible, and as shown in FIG. 1, from -40 ° C. to 100 ° C., 1 ° C./min. The thermal expansion hysteresis is obtained by dividing the difference in dimensions (L ₂ -L ₁ ) by the dimension L between the temperature increasing process that increases the temperature at a rate of 1% and the temperature decreasing process that decreases from 100 ° C. to −40 ° C. at a rate of 1 ° C./min. small.

That is, whether or not voids or cracks occur in the crystal grain boundaries of crystallized glass depends on the type of crystal. A crystal having a molar ratio of Li ₂ O: Al ₂ O ₃ : SiO ₂ = 1: 1: 2 has a large anisotropy in thermal expansion behavior between the a-axis and the c-axis of the crystal. By cooling the crystallized glass precipitated at a high crystallinity from the crystallization temperature, a large thermal expansion strain is generated, and voids and cracks are generated at the crystal grain boundaries.

However, in the present invention, by increasing the proportion of SiO ₂ , the anisotropy of the thermal expansion behavior can be reduced between the a-axis and the c-axis of the precipitated crystal, so that the thermal expansion strain is small and there are voids in the crystal grain boundaries. And cracks do not substantially occur.

  The main crystal refers to all crystal seeds having a relatively large amount of precipitation. That is, in X-ray diffraction, when the intensity of the main peak of the crystal seed having the highest precipitation ratio is 100, all of the precipitated crystal seeds having the main peak intensity ratio of 5 or more are defined as the main crystal.

When the crystallized glass of the present invention is in mass% and the total amount of Na ₂ O, K ₂ O, MgO, CaO, SrO, and BaO is 0 to 0.8%, the average heat at −40 to 100 ° C. The expansion coefficient is preferably −16 to −45 × 10 ⁻⁷ / ° C. Since Na ₂ O, K ₂ O, MgO, CaO, SrO, and BaO are components that shift the thermal expansion coefficient in the positive direction in the glass, the average thermal expansion coefficient when 0.8% or more is contained. It tends to be larger in the positive direction than −16 × 10 ⁻⁷ / ° C.

Crystallized glass of the present invention, in _{mass%, SiO 2 49~70%, Al} 2 O 3 21~34%, Li 2 O 3.8~10.0%, ZrO 2 0.5~2.5% When TiO ₂ is contained in an amount of 0 to 1.0% and P ₂ O ₅ is contained in an amount of 0 to 2.0%, it is difficult to be devitrified and easy to mold, and the bending strength is high.

  Hereinafter, the reason which limited the composition of the crystallized glass of this invention is demonstrated.

SiO ₂ is a main component constituting the glass network and a component constituting the precipitated crystals. When the SiO ₂ content is less than 49%, it becomes difficult to vitrify and it becomes difficult to precipitate a β-quartz solid solution or β-eucryptite solid solution having a desired crystal grain size as a main crystal. In addition, it becomes difficult to suppress the occurrence of voids and cracks at the grain boundaries. On the other hand, if it exceeds 70%, the melting temperature of the glass becomes high. A preferable range of SiO ₂ is 50 to 69%, and a more preferable range is 52 to 68%.

Al ₂ O _{3 is} also a component constituting a glass network and a component constituting a crystal. When Al ₂ O ₃ is less than 21%, it is difficult to precipitate a desired crystal. On the other hand, if it exceeds 34%, the glass tends to be devitrified. A preferable range of Al ₂ O ₃ is 22.5 to 33%, and a more preferable range is 23 to 32%.

Li ₂ O is a constituent component of β-quartz solid solution crystal or β-eucryptite solid solution crystal. If the amount of Li ₂ O is less than 3.8%, it becomes difficult to increase the crystallinity to 70% or more. On the other hand, if it exceeds 10.0%, the glass tends to devitrify and it is difficult to incorporate all Li atoms into the crystal. In addition, Li atoms that have not been incorporated become a component constituting the glass matrix and have a function of positively increasing the thermal expansion coefficient, making it difficult to obtain a large negative thermal expansion coefficient. A preferable range of Li ₂ O is 4.2 to 9.8%, and a more preferable range is 4.4 to 9.6%.

ZrO ₂ is a component having an action of forming crystal nuclei in glass. If ZrO ₂ is less than 0.5%, the nucleation action becomes insufficient, and crystals having a desired particle size cannot be uniformly deposited. On the other hand, if it exceeds 2.5%, devitrification tends to occur, so that it becomes difficult to form glass, which is not preferable. In addition, Zr atoms that have not become crystal nuclei become a component constituting the glass matrix and have a function of positively increasing the thermal expansion coefficient, making it difficult to obtain a large negative thermal expansion coefficient. A preferable range of ZrO ₂ is 0.7 to 2.5%, and a more preferable range is 1 to 2.5%.

TiO ₂ is a component having an action of forming crystal nuclei. When TiO ₂ is more than 1%, β-spodumene solid solution is likely to precipitate, and it becomes difficult to obtain a negatively large thermal expansion coefficient, and the average crystal grain size is small and the bending strength tends to be low.

P ₂ O ₅ is a component that promotes the growth of crystal nuclei. If it exceeds 2.0%, P atoms that have not been incorporated into the crystal become a component of the glass matrix and have a function of positively increasing the thermal expansion coefficient, so it is difficult to obtain a large negative thermal expansion coefficient. It becomes. A preferable range of P ₂ O ₅ is 0 to 1.8%, and a more preferable range is 0 to 1.5%.

When the total amount of nucleating agents TiO ₂ , ZrO ₂ and P ₂ O ₅ is less than 0.5%, crystals are not uniformly precipitated in the glass matrix. If it exceeds 2.9%, the glass becomes devitrified and molding becomes difficult, and all nucleating agents do not become crystal nuclei, and the nucleating agents that have not become crystal nuclei constitute a glass matrix. Since it becomes a component and has an action of increasing the thermal expansion coefficient positively, it is difficult to obtain a large negative thermal expansion coefficient. A preferable range is 0.5 to 2.5%.

The crystallized glass of the present invention is preferably% by mass, ZnO 0 to 9%, and the total amount of Li ₂ O and ZnO is 5.0 to 18%.

ZnO is a component constituting a β-quartz solid solution crystal or β-eucryptite solid solution crystal like Li ₂ O, and has a function of increasing the crystallinity. If the ZnO content exceeds 9%, the glass tends to devitrify and it is difficult to incorporate all Zn into the crystal. The Zn that has not been incorporated into the crystal becomes a component constituting the glass matrix and has a coefficient of thermal expansion. Since it has an action of increasing positively, it is difficult to obtain a large negative thermal expansion coefficient. The preferable range of ZnO is 0 to 8%, and the more preferable range is 0 to 7%.

Further, when the total amount of Li ₂ O and ZnO is less than 5.0%, the degree of crystallinity is difficult to increase, so the thermal expansion coefficient is difficult to be negative, and when it exceeds 18%, it is not taken into the crystal. Li and Zn are components constituting the glass matrix and have an action of increasing the thermal expansion coefficient positively, so that it is difficult to obtain a negative thermal expansion coefficient.

In the present invention, other components, for example, As ₂ O ₃ , Sb ₂ O ₃ and SnO ₂ may be added as 0 to 2%, respectively, as a clarifier. Further, as a refractive index adjustment, a total amount of 0 to 5% of rare earth such as WO ₃ , La ₂ O ₃ , CeO ₂ , GeO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ , Gd ₂ O ₃ may be added. good.

When the crystallized glass of the present invention is mass% and the degree of crystallinity is 70% or more, the thermal expansion coefficient of the main crystal β-quartz solid solution or β-eucryptite solid solution is largely reflected and negatively increased. Therefore, the average coefficient of thermal expansion at −40 ° C. to 100 ° C. is preferably −16 to −45 × 10 ⁻⁷ / ° C. A preferable crystallinity range is 80% or more.

  The crystallized glass of the present invention preferably has an average crystal grain size of 0.2 to 10.0 μm. When the average crystal grain size is smaller than 0.2 μm, if a load is applied to the crystallized glass and a crack is generated, propagation of the crack is difficult to be inhibited by the crystal grain, so that the bending strength is difficult to improve. Moreover, when larger than 10.0 micrometers, when heating and cooling are repeated to crystallized glass, a space | gap and a crack are easy to produce in a crystal grain boundary, and bending strength will fall easily.

The crystallized glass of the present invention comprises a total amount (A) of TiO ₂ , ZrO _2, and P ₂ O ₅ which are crystal nucleating agents, and a total amount (B) of Li ₂ O and ZnO which are components constituting the crystal. The ratio B / A is preferably 2.6 to 10. If the ratio B / A of the total amount (A) of TiO ₂ , ZrO ₂ and P ₂ O _{5 and} the total amount (B) of Li ₂ O and ZnO, which are nucleating agents, is smaller than 2.6, If the component constituting the crystal is too small relative to the forming agent, it is difficult to increase the bending strength because the crystal grain size is difficult to grow to 0.2 μm. In addition, the nucleating agent that has not been incorporated as crystal nuclei becomes a component constituting the glass matrix and has a function of positively increasing the thermal expansion coefficient, so that it is difficult to obtain a large negative thermal expansion coefficient. On the other hand, if it is larger than 10, that is, if there are too many components constituting the crystal with respect to the nucleating agent, it is difficult for the crystal to precipitate uniformly in the glass matrix, so that uneven bending strength tends to occur. The preferred range is 2.6 to 9.5, more preferably 2.6 to 9.0.

  Moreover, as for the crystallized glass of this invention, it is desirable to heat-process crystalline glass at 850-950 degreeC. That is, if the crystallization temperature is less than 850 ° C., the crystallinity of the β-quartz solid solution or β-eucryptite solid solution as the main crystal is difficult to be 70% by mass or more, and if it is higher than 950 ° C., β-spodumene solid solution is precipitated. It is easy.

  The larger the thermal conductivity, the more preferable the reaction of the compensation member with respect to the temperature change, and the more preferable is 1.5 W / K or more.

  Since the crystallized glass of the present invention has a high transmittance of infrared rays (for example, wavelength 1500 nm) besides the device for optical communication, it can be used as a support material for an infrared transmission filter or a member that deforms due to temperature change. In addition, since it can be processed to a thickness of submicron and can be optically polished, it can be used as a precision instrument component, for example, a reflection plate with a reflection film formed on the optical polishing surface or an absorption plate with an uneven film. is there. It can also be used as a powder for PDP barrier ribs, green sheets or multilayer substrate fillers, or for adhesive fillers or electro-mirrors used for sealing materials.

  In the crystallized glass of the present invention, the crystal transition temperature at which crystals are transferred from β-quartz solid solution or β-eucryptite to β-spodumene solid solution is preferably 1000 ° C. or more, and more preferably not. If the temperature is lower than 1000 ° C., the thermal expansion coefficient may change due to crystal transition when used in a precision instrument part that is exposed to high temperatures, which may cause problems. In addition, since the crystallized glass of this invention becomes high crystallinity, it is thought that a crystal transition temperature becomes high.

  Hereinafter, the crystallized glass of the present invention will be described in detail based on examples.

  Tables 1 and 2 show Examples 1 to 7 and Comparative Examples 1 to 5.

  Examples 1-7 and Comparative Examples 1-5 were prepared as follows.

  First, raw materials were prepared so as to obtain each composition in the table, and then put in a platinum crucible and melted at 1580 ° C. for 20 hours. Next, two 5 mm thick spacers were placed on the carbon plate, molten glass was poured between the spacers, and the surface was smoothed with a roller to form a 5 mm thick glass plate and cooled to room temperature. .

  Next, the glass plate was subjected to nucleation treatment at 780 ° C. for 2 hours, followed by crystallization treatment at the crystallization temperature in the table for 1 hour, and then cooled to room temperature to produce crystallized glass. The main crystals were all β-eucryptite solid solutions.

  The liquidus temperature was measured by measuring the highest temperature at which devitrification occurred, taking out the platinum boat after putting the glass plate cut into a strip shape on a platinum boat and placing it in a temperature gradient furnace and holding it for 18 hours. The temperature was taken as the liquidus temperature.

  Presence / absence and crystallinity of the β-spodumene solid solution were measured using an X-ray diffraction method (Rigaku X-ray diffractometer). The β-spodumene solid solution was identified by using a peak around 23.8 °.

  The average crystal grain size and the presence or absence of voids or cracks in grain boundaries were measured with a scanning electron microscope (JSM-5400, manufactured by JEOL Ltd.). The average crystal grain size is an average value obtained by measuring the grain sizes of 100 randomly selected crystals.

  The thermal expansion hysteresis and thermal expansion coefficient at −40 to + 100 ° C. were measured using a dilatometer (TD-5000S manufactured by Mac Science). In the measurement of thermal expansion hysteresis, the temperature was increased and decreased between 1 and 100 ° C. at 1 ° C./min.

  The bending strength is 3 × 4 × 36 mm, and a 3 × 4 × 36 mm test piece is prepared according to JIS R 1601 using a bending tester (Shimadzu Corporation EZTest-500N) at a fulcrum distance of 30 mm and a crosshead speed of 0.5 mm / min. A point bending test was performed.

  The thermal conductivity was measured using a laser flash method (TC-7000, manufactured by Vacuum Riko) for each sample processed to a diameter of 9.5 mm and a thickness of 2 mm.

  Regarding the crystal transition temperature, for each of Examples 1, 2 and Comparative Example 5, each of the prepared samples was again heated at a heating rate of 2 ° C./min, and the samples were taken out at intervals of 25 ° C. from 900 ° C. The presence or absence of β-spodumene solid solution crystals was measured using a (Rigaku X-ray diffractometer), and the lowest temperature was taken out while β-spodumene solid solution precipitated.

  The dielectric loss was obtained by measuring the dielectric constant (ε) and loss tan δ at 1 MHz at 25 ° C., and calculating the dielectric loss (ε · tan δ), which is the product of these. The apparatus was measured using an impedance analyzer (Yokogawa Hewlett Packard 4192A).

  The transmittance was measured by using a spectrophotometer (UV3100PC, manufactured by Shimadzu Corporation) to measure the transmittance of light having wavelengths of 500 nm, 780 nm, and 1500 nm by optically polishing both surfaces with a sample thickness of 3 mm.

As is clear from Tables 1 and 2, Examples 1 to 7 had a thermal expansion coefficient that was negatively greater than −22 × 10 ⁻⁷ / ° C., and the bending strength was 160 MPa or more. In all cases, the liquidus temperature was 1440 ° C. or lower. Moreover, precipitation of β-spodumene solid solution and no intergranular voids or cracks were observed. Furthermore, the hysteresis of thermal expansion was 1 ppm or less, and the crystallinity was 86% or more.

In Examples 1 and 2, the thermal conductivity was 1.7 W / m, the crystal transition temperature was 1000 ° C., and the dielectric loss was 19 × 10 ⁻³ and 20 × 10 ⁻³ , respectively.

On the other hand, as apparent from Table 2, Comparative Examples 1 to 3 having no voids or cracks in the crystal grain boundaries all have a thermal expansion coefficient of −6 to −33 × 10 ⁻⁷ / ° C., and the bending strength is It was 155 MPa or less.

Further, Comparative Example 4 having voids and cracks at the crystal grain boundaries had a thermal expansion coefficient of −40 × 10 ⁻⁷ / ° C., a bending strength of 27 MPa, and a thermal conductivity of 0.9 W / m. . When the thermal conductivity is low in temperature compensation, the entire sample temperature cannot follow the temperature change, and the amount of change in the reflection wavelength tends to increase, so that the thermal conductivity is preferably high. In this respect as well, Examples 1 and 2 showed good results.

  Moreover, all of Comparative Examples 1-5 had liquidus temperature of 1470 degreeC or more.

  As described above, since the crystallized glass of the present invention has a large negative thermal expansion coefficient and high bending strength, is hard to be devitrified and can be easily molded, an optical communication device such as an FBG or an optical waveguide device. It is suitable for the temperature compensation member.

It is a graph which shows the thermal expansion hysteresis in the range of -40-100 degreeC.

Claims (8)

A crystallized glass in which a β-quartz solid solution or a β-eucryptite solid solution is precipitated as a main crystal, and an average coefficient of thermal expansion at −40 ° C. to 100 ° C. is −16 to −45 × 10 ⁻⁷ / ° C., The total amount of TiO ₂ , ZrO ₂ and P ₂ O ₅ is 0.5 to 2.9% by mass%, and the molar ratio (Li ₂ O + ZnO) / SiO ₂ is 0.15 to 0.35. Characterized crystallized glass. _2. The crystallized glass according to claim 1, wherein the total amount of Na ₂ O, K ₂ O, MgO, CaO, SrO, and BaO is 0 to 0.8% by mass%. By _{mass%, SiO 2 49~70%, Al} 2 O 3 21~34%, Li 2 O 3.8~10.0%, ZrO 2 0.5~2.5%, TiO 2 0~1.0 %, crystallized glass of claim 1 or 2, characterized in that it contains P ₂ O ₅ 0 to 2.0%. By mass%, at 0 to 9% ZnO, crystallized glass according to any one of claims 1 to 3 the total amount of Li ₂ O and ZnO is characterized in that it is a 5.0 to 18%.   The crystallized glass according to any one of claims 1 to 3, wherein the crystallinity is 70% or more by mass%.   The crystallized glass according to any one of claims 1 to 5, wherein an average crystal grain size is 0.2 to 10.0 µm. The ratio B / A of the total amount (A) of TiO ₂ , ZrO ₂ and P ₂ O _{5 and} the total amount (B) of Li ₂ O and ZnO is 2.6-10. The crystallized glass in any one of -6.   An optical communication device comprising the crystallized glass according to claim 1 as a temperature compensating member.

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