Compound calcium guanidine nitrate and calcium guanidine nitrate birefringent crystals and preparation method and use thereof

Abstract

The present invention provides a compound, calcium guanidine nitrate, and a birefringent calcium guanidine nitrate crystal, as well as a preparation method and use thereof. The chemical formula of the compound is [C(NH2)3]2Ca(NO3)4(H2O)2, the molecular weight is 444.33, and the compound is prepared by a solvent thermal method. The crystal chemical formula is [C(NH2)3]2Ca(NO3)4(H2O)2, the molecular weight is 444.33, and the crystal belongs to the monoclinic system with a space group of C 2 / c , the unit cell parameters are a =20.319(3)Å, b =6.5717(8)Å, c =14.2195(16)Å, α =90°, β =116.399(5)°, c =90°, the unit cell volume is 1700.8(4)Å 3 , with a transmittance range of 281-1600 nm and a birefringence index between 0.152 (1064 nm) and 0.23 (281 nm). Grown using a room-temperature aqueous solution method, the resulting birefringent crystals possess moderate mechanical hardness, are easily cut, polished, and stored, and are easy to grow under simple growth conditions. They are insoluble in water, non-deliquescent, and stable in air. They exhibit a wide transmittance range and birefringence, and can be used to fabricate polarization beam splitters, phase delay devices, and electro-optical modulators.

Description

Technical Field

[0001] The present invention relates to a compound guanidine calcium nitrate and a guanidine calcium nitrate birefringent crystal as well as a preparation method and application thereof. Background Art

[0002] Birefringence refers to the phenomenon in which a single incident ray of light produces two refracted rays. The fundamental reason for this phenomenon lies in the anisotropy of the crystal material. The law of refraction generally applies only to isotropic media. For anisotropic crystals, at least one of the two refracted light waves produced by birefringence generally violates the law of refraction. Different directions of incident light, different crystal structures, and different spatial orientations result in different birefringence properties. Due to birefringence, a beam of natural light passing through parallel plates made of a certain anisotropic crystal is decomposed into two offset but parallel transmitted light waves, resulting in an offset doubly refracted image. This type of crystal is called a birefringent crystal. The birefringence of a crystal is a key optical parameter of optoelectronic functional crystal materials. Leveraging the properties of birefringent crystals, they are key materials for the manufacture of optical components such as optical isolators, circulators, beam shifters, optical polarizers, and optical modulators.

[0003] Birefringent optical crystals have important applications in many fields, including scientific research, transportation, national defense, and industry. With the rapid development of the laser industry, the search for new birefringent materials with superior performance is urgent. Commonly used birefringent materials include yttrium vanadate, barium metaborate, lithium niobate, and calcite. However, these birefringent materials all have drawbacks. YVO4 is a promising artificial birefringent crystal, but due to its high melting point, it must be grown in an iridium crucible in a weak oxygen atmosphere, which results in iridium valence changes during growth, reducing crystal quality and making it difficult to obtain high-quality crystals. α-BaB2O4 is prone to cracking during growth due to solid-state phase transitions. LiNbO3 crystals are easy to obtain in large sizes, but their birefringence is too low. Calcite, which primarily exists in its natural form, is difficult to synthesize artificially, resulting in small sizes and high impurity content, making it unsuitable for large-scale optical polarizing components. Calcite is also prone to dissociation, making processing difficult and resulting in low crystal utilization. In view of this, it is very necessary to find a birefringent crystal with a large birefringence, good and stable comprehensive performance parameters, and easy to grow high-quality large-sized bulk crystals.

[0004] The compound calcium guanidine nitrate crystal synthesized by the invention can be used as a Glan prism, a polarizing prism, a polarization beam splitter, an optical isolator, a circulator, a beam shifter, an optical polarizer, an optical modulator and the like due to its large birefringence. Summary of the Invention

[0005] The present invention aims to provide a compound, calcium guanidine nitrate, the chemical formula of which is

[0006] [C(NH2)3]2Ca(NO3)4(H2O)2, molecular weight 444.33, prepared by solvothermal method.

[0007] Another object of the present invention is to provide birefringent calcium guanidine nitrate crystals, the chemical formula of which is [C(NH2)3]2Ca(NO3)4(H2O)2, the molecular weight of which is 444.33, the crystal system of which is monoclinic, the space group of which is C2 / c, and the unit cell parameters of which are α=90°,β=116.399(5)°,γ=90°, the unit cell volume is

[0008] Another object of the present invention is to provide a method for growing birefringent crystals of calcium guanidine nitrate.

[0009] Another object of the present invention is to provide a use of calcium guanidine nitrate birefringent crystals, which are suitable for making optical communication components such as Glan prisms, polarizing prisms, polarization beam splitters, optical isolators, circulators, beam shifters, optical polarizers and optical modulators.

[0010] The compound guanidine calcium nitrate described in the present invention has a chemical formula of [C(NH2)3]2Ca(NO3)4(H2O)2, a molecular weight of 444.33, and is prepared by a solvent thermal method.

[0011] The preparation method of the compound guanidine calcium nitrate is prepared by a solvent thermal method, and the specific operation is carried out according to the following steps:

[0012] a. Place guanidine carbonate in a 500 mL Teflon beaker, mechanically stir the material with a spatula, slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution, heat the clear solution on a hot plate at 80° C. to remove excess water and carbon dioxide gas to obtain white or colorless crystalline raw guanidine nitrate, grind the raw guanidine nitrate, and irradiate it under an infrared lamp for 30 minutes to ensure that all water is removed;

[0013] b. The guanidine nitrate prepared in step a and calcium nitrate tetrahydrate were placed in a polytetrafluoroethylene liner of a hydrothermal reactor in a molar ratio of 2:1. The materials were mechanically stirred with a spatula, and then 2 mL of deionized water was added. The liner was then encapsulated in a stainless steel shell and placed in an electric constant temperature forced air drying oven for heating and reaction. The electric constant temperature forced air drying oven was heated to 180° C. for 3 hours, kept warm for 4320 minutes, and then cooled to room temperature for 6500 minutes to obtain the compound guanidine calcium nitrate.

[0014] A birefringent crystal of calcium guanidine nitrate, the chemical formula of the crystal is [C(NH2)3]2Ca(NO3)4(H2O)2, the molecular weight is 444.33, belongs to the monoclinic system, the space group is C2 / c, and the unit cell parameters are α=90°,β=116.399(5)°,γ=90°, the unit cell volume is

[0015] The preparation method of the calcium guanidine nitrate birefringent crystal adopts a room temperature aqueous solution method to grow the calcium guanidine nitrate birefringent crystal, and the specific operation is carried out according to the following steps:

[0016] a. Place guanidine carbonate in a 500 mL Teflon beaker, mechanically stir the material with a spatula, and slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80° C. to remove excess water and carbon dioxide gas to obtain white or colorless crystalline raw guanidine nitrate. Grind the raw guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure that all water is removed.

[0017] b. Dissolve the guanidine nitrate and calcium nitrate tetrahydrate prepared in step a in deionized water at a molar ratio of 2:1, add 10 mL of deionized water, adjust the pH value to 1 with 1 mol / L nitric acid solution, and treat in an ultrasonic bath at 25° C. for 15 min to fully mix and dissolve;

[0018] Alternatively, directly weigh guanidine carbonate and calcium nitrate tetrahydrate in a molar ratio of 1:1, place them in a conical flask, add nitric acid solution with a concentration of 1 mol / L, adjust the pH of the solution to 1, and treat it in an ultrasonic bath at 25°C for 15 minutes to fully dissolve and mix;

[0019] c. After the mixed solution in step b is naturally cooled to room temperature, it is sealed with plastic wrap and several small holes are punched in the plastic wrap or the solution system is directly exposed, placed in a clean, pollution-free environment with no air convection, and allowed to stand at room temperature for 30-60 days;

[0020] d. After the solution in step c grows crystal particles at the bottom of the container, the temperature is lowered to room temperature at a rate of 2-3°C / day or maintained at a constant temperature of 25-35°C for 10-30 days. When the crystals continue to grow and there is no significant change in crystal size, the growth is completed, and the solution containing the crystals is filtered to obtain birefringent calcium guanidine nitrate crystals.

[0021] The guanidine calcium nitrate birefringent crystal is used in preparing an optical isolator, a circulator, a beam displacer, an optical polarizer or an optical modulator.

[0022] The optical polarizer is a polarizing beam splitter prism.

[0023] The polarization beam splitter prism is a Glan prism, a Wollaston prism or a Rochon prism.

[0024] The birefringent calcium guanidine nitrate crystals of the present invention are synthesized by a solvothermal method and grown by a room temperature aqueous solution method. The chemical reaction formula is as follows:

[0025] (1) [C(NH2)3]2CO3+2HNO3+Ca(NO3)2·4H2O → C(NH2)3]2Ca(NO3)4(H2O)2+3H2O+CO2↑;

[0026] (2) 2C(NH2)3NO3+Ca(NO3)2·4H2O → [C(NH2)3]2Ca(NO3)4(H2O)2+2H2O;

[0027] (3) [C(NH2)3]2CO3+4HNO3+CaO → C(NH2)3]2Ca(NO3)4(H2O)2 +CO2↑;

[0028] (4) [C(NH2)3]2CO3+4HNO3+CaCO3 → C(NH2)3]2Ca(NO3)4(H2O)2 +2CO2↑;

[0029] (5) [C(NH2)3]2CO3+4HNO3+Ca(OH)2 → C(NH2)3]2Ca(NO3)4(H2O)2 +CO2↑+H2O;

[0030] (6) 2C(NH2)3NO3+2HNO3+CaO+H2O → C(NH2)3]2Ca(NO3)4(H2O)2;

[0031] (7) 2C(NH2)3NO3+2HNO3+CaCO3+H2O → C(NH2)3]2Ca(NO3)4(H2O)2 +CO2↑;

[0032] (8) 2C(NH2)3NO3+2HNO3+Ca(OH)2 → C(NH2)3]2Ca(NO3)4(H2O)2.

[0033] The calcium guanidine nitrate birefringent crystal of the present invention is used in the infrared-ultraviolet band, has a transmission range of 281-1600 nm, and a birefringence between 0.152 (1064 nm) and 0.23 (281 nm).

[0034] The birefringent calcium guanidine nitrate crystal of the present invention has a chemical formula of [C(NH2)3]2Ca(NO3)4(H2O)2, a molecular weight of 444.33, belongs to the monoclinic system, has a space group of C2 / c, and a unit cell parameter of α=90°,β=116.399(5)°,γ=90°, the unit cell volume is Its transmission range is 281-1600nm, and its birefringence ranges from 0.152 (1064nm) to 0.23 (281nm). The crystals are easy to grow, cut, grind, polish, and store; they are grown using a room-temperature aqueous solution method. The resulting crystals are stable in air. They can be used to fabricate polarization beamsplitting prisms such as Glan-type prisms, Wollaston prisms, Rochon prisms, or beam-splitting polarizers, finding important applications in optics and communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The powder XRD spectrum of the compound [C(NH2)3]2Ca(NO3)4(H2O)2 of the present invention is shown in FIG.

[0036] Figure 2 This is a structural diagram of the [C(NH2)3]2Ca(NO3)4(H2O)2 crystal of the present invention;

[0037] Figure 3 The UV-visible transmittance and crystal photograph of the [C(NH2)3]2Ca(NO3)4(H2O)2 crystal of the present invention are shown;

[0038] Figure 4 This is a graph showing the birefringence calculation of [C(NH2)3]2Ca(NO3)4(H2O)2 according to the present invention;

[0039] Figure 5 Schematic diagram of the wedge-shaped birefringent crystal polarization beam splitter of the present invention, wherein 1 is the incident light, 2 is the o-light, 3 is the e-light, 4 is the optical axis, and 5 is the guanidine calcium nitrate [C(NH2)3]2Ca(NO3)4(H2O)2 birefringent crystal;

[0040] Figure 6 Schematic diagram of the optical isolator of the present invention;

[0041] Figure 7 Schematic diagram of a beam displacer for making crystals grown by the method of the present invention, wherein 1 is incident light, 2 is o-light, 3 is e-light, 4 is the optical axis, 5 is the birefringent crystal of guanidine calcium nitrate [C(NH2)3]2Ca(NO3)4(H2O)2, 6 is the light transmission direction, and 7 is the optical axis plane. DETAILED DESCRIPTION

[0042] The present invention is further described below with reference to the following examples. It should be noted that the following examples are not intended to limit the scope of the present invention, and any improvements made based on the present invention do not violate the spirit of the present invention. Unless otherwise specified, the raw materials and equipment used in the present invention are commercially available.

[0043] Example 1

[0044] According to the reaction formula (1): [C(NH2)3]2CO3+2HNO3+Ca(NO3)2·4H2O→C(NH2)3]2Ca(NO3)4(H2O)2+3H2O+CO2↑, the compound is prepared:

[0045] Guanidine carbonate and calcium nitrate tetrahydrate were placed in a 23 mL hydrothermal reactor lined with polytetrafluoroethylene (PTFE) in a 1:1 molar ratio. Stir mechanically with a spatula and slowly add nitric acid dropwise until bubbles ceased, resulting in a clear solution. The liner was then enclosed in a stainless steel housing and heated in an electric constant-temperature forced-air drying oven. The temperature was raised to 180°C over 3 hours, maintained at this temperature for 4320 minutes, and then cooled to room temperature over 6500 minutes to obtain the compound, guanidine calcium nitrate.

[0046] Example 2

[0047] According to reaction formula (2): 2C(NH2)3NO3+Ca(NO3)2·4H2O→[C(NH2)3]2Ca(NO3)4(H2O)2+2H2O, the compound is prepared:

[0048] a. Place guanidine carbonate in a 500mL Teflon beaker and mechanically stir the material with a spatula. Slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80°C to remove excess water and carbon dioxide gas to obtain white or colorless crystalline raw guanidine nitrate. Grind the raw guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure complete removal of water.

[0049] b. Place the guanidine nitrate prepared in step a and calcium nitrate tetrahydrate in a 2:1 molar ratio into a polytetrafluoroethylene liner of a hydrothermal reactor and mechanically stir the materials with a spatula. After thorough mixing, encapsulate the liner in a stainless steel housing and heat the reaction in an electric constant temperature forced air drying oven. Raise the temperature in the electric constant temperature forced air drying oven to 170° C. over 3 hours, maintain the temperature for 4320 minutes, and then cool to room temperature over 6500 minutes to obtain the compound guanidine calcium nitrate.

[0050] Example 3

[0051] According to reaction formula (3): [C(NH2)3]2CO3+4HNO3+CaO→C(NH2)3]2Ca(NO3)4(H2O)2+CO2↑, the compound is prepared:

[0052] Guanidine carbonate and calcium oxide were placed in a 1:1 molar ratio in a polytetrafluoroethylene-lined 23mL hydrothermal reactor. Stir mechanically with a spatula and slowly add nitric acid dropwise until bubbles ceased, yielding a clear solution. The liner was then enclosed in a stainless steel housing and heated in an electric constant-temperature forced-air drying oven. The oven temperature was raised to 180°C over 3 hours, maintained at this temperature for 4320 minutes, and then cooled to room temperature over 6500 minutes to yield guanidine calcium nitrate.

[0053] Example 4

[0054] According to reaction formula (4): [C(NH2)3]2CO3+4HNO3+CaCO3→C(NH2)3]2Ca(NO3)4(H2O)2+2CO2↑, the compound was prepared by placing guanidine carbonate and calcium carbonate in a 1:1 molar ratio in a polytetrafluoroethylene liner of a 23 mL hydrothermal reactor. Stirring was performed mechanically with a spatula. Nitric acid was slowly added dropwise until no bubbles were generated, resulting in a clear solution. The liner was then encapsulated in a stainless steel housing and placed in an electric constant temperature forced air drying oven for heating. The temperature in the electric constant temperature forced air drying oven was raised to 180°C over 3 hours, maintained at this temperature for 4320 minutes, and then cooled to room temperature for 6500 minutes to obtain the compound guanidine calcium nitrate.

[0055] Example 5

[0056] According to reaction formula (5): [C(NH2)3]2CO3+4HNO3+Ca(OH)2→C(NH2)3]2Ca(NO3)4(H2O)2+CO2↑+H2O, the compound is prepared:

[0057] Guanidine carbonate and calcium hydroxide were placed in a 1:1 molar ratio in a polytetrafluoroethylene-lined 23mL hydrothermal reactor. Stir mechanically with a spatula and slowly add nitric acid dropwise until bubbles ceased, yielding a clear solution. The liner was then enclosed in a stainless steel housing and heated in an electric constant-temperature forced-air drying oven. The oven temperature was raised to 180°C over 3 hours, maintained at this temperature for 4320 minutes, and then cooled to room temperature over 6500 minutes to yield guanidine calcium nitrate.

[0058] Example 6

[0059] According to reaction formula (6): 2C(NH2)3NO3+2HNO3+CaO+H2O→C(NH2)3]2Ca(NO3)4(H2O)2, the compound is prepared:

[0060] a. Place guanidine carbonate in a 500mL Teflon beaker and mechanically stir the material with a spatula. Slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80°C to remove excess water and carbon dioxide gas to obtain white or colorless crystalline raw guanidine nitrate. Grind the raw guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure complete removal of water.

[0061] b. Place the guanidine nitrate prepared in step a and calcium oxide in a 2:1 molar ratio into a polytetrafluoroethylene liner of a hydrothermal reactor. Mechanically stir the materials with a spatula while adding nitric acid dropwise at a 2:1 molar ratio of nitric acid to calcium oxide. After thorough mixing, encapsulate the liner in a stainless steel housing and heat the reaction in an electric constant temperature forced air drying oven. Raise the temperature in the electric constant temperature forced air drying oven to 170° C. over 3 hours, maintain the temperature for 4320 minutes, and then cool to room temperature for 6500 minutes to obtain the compound guanidine calcium nitrate.

[0062] Example 7

[0063] According to reaction formula (7): 2C(NH2)3NO3+2HNO3+CaCO3+H2O→C(NH2)3]2Ca(NO3)4(H2O)2+CO2↑, the compound is prepared:

[0064] a. Place guanidine carbonate in a 500mL Teflon beaker and mechanically stir the material with a spatula. Slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80°C to remove excess water and carbon dioxide gas to obtain white or colorless crystalline raw guanidine nitrate. Grind the raw guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure complete removal of water.

[0065] b. The guanidine nitrate prepared in step a and calcium carbonate were placed in a polytetrafluoroethylene liner of a hydrothermal reactor in a molar ratio of 2:1. The materials were mechanically stirred with a spatula while adding a nitric acid solution dropwise until no bubbles were generated. The liner was then encapsulated in a stainless steel shell and placed in an electric constant temperature forced air drying oven for heating and reaction. The electric constant temperature forced air drying oven was heated to 170° C. for 3 hours, kept warm for 4320 minutes, and then cooled to room temperature for 6500 minutes to obtain the compound guanidine calcium nitrate.

[0066] Example 8

[0067] According to reaction formula (8): 2C(NH2)3NO3+2HNO3+Ca(OH)2→C(NH2)3]2Ca(NO3)4(H2O)2, the compound is prepared:

[0068] a. Place guanidine carbonate in a 500mL Teflon beaker and mechanically stir the material with a spatula. Slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80°C to remove excess water and carbon dioxide gas to obtain white or colorless crystalline raw guanidine nitrate. Grind the raw guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure complete removal of water.

[0069] b. Place the guanidine nitrate prepared in step a and calcium hydroxide in a 2:1 molar ratio into a polytetrafluoroethylene liner of a hydrothermal reactor. Mechanically stir the materials with a spatula while adding nitric acid dropwise at a 2:1 molar ratio of nitric acid to calcium hydroxide. After thorough mixing, encapsulate the liner in a stainless steel housing and heat the reaction in an electric constant temperature forced air drying oven. Raise the temperature in the electric constant temperature forced air drying oven to 170° C. over 3 hours, maintain the temperature for 4320 minutes, and then cool to room temperature for 6500 minutes to obtain the compound guanidine calcium nitrate.

[0070] Example 9

[0071] According to the reaction formula (1) [C(NH2)3]2CO3+2HNO3+Ca(NO3)2·4H2O→[C(NH2)3]2Ca(NO3)4(H2O)2+3H2O+CO2↑, birefringent calcium guanidine nitrate crystals are grown:

[0072] a. Place guanidine carbonate in a 500 mL Teflon beaker and mechanically stir the material with a spatula. Slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80° C. to remove excess water and carbon dioxide gas to obtain white guanidine nitrate. Grind the guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure that all water is removed.

[0073] b. Dissolve the guanidine nitrate and calcium nitrate tetrahydrate prepared in step a in deionized water at a molar ratio of 2:1 until completely dissolved, add 10 mL of deionized water, adjust the pH value to 1 with 1 mol / L nitric acid solution, and treat in an ultrasonic bath at 25°C for 15 min to fully mix and dissolve;

[0074] c. After the mixed solution in step b is naturally cooled to room temperature, it is placed in a clean, pollution-free environment with no air convection, sealed with a membrane, and several small holes are punched in the membrane, and allowed to stand at room temperature for 30 days;

[0075] d. Wait for the solution in step c to grow crystal particles at the bottom of the container. After the crystals continue to grow, cool the temperature to room temperature at a rate of 2°C / day and keep the temperature constant for 10 days. After the growth is completed, filter the solution containing the crystals to obtain a 3.2×2.5×1.2 mm 3 Large-sized transparent birefringent crystals of calcium guanidine nitrate.

[0076] Example 10

[0077] According to the reaction formula (1) [C(NH2)3]2CO3+2HNO3+Ca(NO3)2·4H2O→[C(NH2)3]2Ca(NO3)4(H2O)2+3H2O+CO2, birefringent calcium guanidine nitrate crystals are grown:

[0078] Guanidine carbonate and calcium nitrate tetrahydrate were weighed directly in a molar ratio of 1:1 and placed in a conical flask. A nitric acid solution with a concentration of 1 mol / L was added to adjust the pH of the solution to 1. The solution was treated in an ultrasonic bath at 25°C for 15 minutes to allow the solution to be fully dissolved and mixed.

[0079] After the solution was cooled naturally to room temperature, it was sealed with a membrane, and then several small holes were punched in the membrane. The solution was placed in a clean, pollution-free environment with no air convection. The reaction temperature was 35°C. After standing for 45 days, several small crystals were formed at the bottom of the container. The crystals continued to grow until there was no obvious change in the size of the crystals. The growth was terminated by cooling at a rate of 2-3°C / day. The solution containing the crystals was filtered to obtain a 3×2×2.2mm 3 Large-sized transparent birefringent crystals of calcium guanidine nitrate.

[0080] Example 11

[0081] According to the reaction formula (2) 2C(NH2)3NO3+Ca(NO3)2·4H2O→[C(NH2)3]2Ca(NO3)4(H2O)2+2H2O, birefringent crystals of calcium guanidine nitrate are grown:

[0082] a. Place guanidine carbonate in a 500 mL Teflon beaker, mechanically stir the material with a spatula, and slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80° C. to remove excess water and carbon dioxide gas to obtain colorless crystalline raw material guanidine nitrate. Grind the guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure that all water is removed.

[0083] b. Dissolve the guanidine nitrate and calcium nitrate tetrahydrate prepared in step a in deionized water at a molar ratio of 2:1 until completely dissolved, add 10 mL of deionized water, adjust the pH value to 1 with 1 mol / L nitric acid solution, and treat in an ultrasonic bath at 25°C for 15 min to fully mix and dissolve;

[0084] c. After the mixed solution in step b is naturally cooled to room temperature, it is placed in a clean, pollution-free environment with no air convection, sealed with plastic wrap, and several small holes are punched in the film or the solution system is directly exposed, and allowed to stand at room temperature for 40 days;

[0085] d. Wait for the solution in step c to grow crystal particles at the bottom of the container, then cool it down to room temperature at a rate of 2°C / day. When the crystals continue to grow and there is no significant change in the size of the crystals, the growth is complete. Filter the solution containing the crystals to obtain 2×1.2×1 mm 3 Large-sized transparent birefringent crystals of calcium guanidine nitrate.

[0086] Example 12

[0087] According to the reaction formula (3) [C(NH2)3]2CO3+4HNO3+CaO→[C(NH2)3]2Ca(NO3)4(H2O)2+CO2↑, birefringent calcium guanidine nitrate crystals are grown:

[0088] a. Place guanidine carbonate in a 500 mL Teflon beaker and mechanically stir the material with a spatula. Slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80° C. to remove excess water and carbon dioxide gas to obtain white guanidine nitrate. Grind the guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure that all water is removed.

[0089] b. Dissolve the guanidine nitrate and calcium oxide prepared in step a in deionized water at a molar ratio of 2:1 until all the solid drugs are dissolved, then add 10 mL of deionized water, adjust the pH value to 1 with 1 mol / L nitric acid solution, and treat in an ultrasonic bath at 25 ° C for 15 min to fully mix and dissolve;

[0090] c. After the mixed solution in step b is naturally cooled to room temperature, it is placed in a clean, pollution-free environment with no air convection, sealed with a membrane, and several small holes are punched in the membrane or the solution system is directly exposed, and allowed to stand at room temperature for 30 days;

[0091] d. Wait for the solution in step c to grow crystal particles at the bottom of the container, wait for the crystals to continue to grow until the crystal size does not change significantly, then cool it down to room temperature at a rate of 3°C / day, filter the solution containing the crystals, and obtain 3×2.2×1mm 3 Large size transparent birefringent crystals of calcium guanidine nitrate.

[0092] Example 13

[0093] According to reaction (3) [C(NH2)3]2CO3+4HNO3+CaO→[C(NH2)3]2Ca(NO3)4(H2O)2+CO2↑, calcium guanidine nitrate crystals are grown:

[0094] Guanidine carbonate and calcium oxide were weighed directly in a molar ratio of 1:1 and placed in a conical flask. A 1 mol / L nitric acid solution was added to the flask to adjust the pH of the solution to 1. The solution was treated in an ultrasonic bath at 25°C for 15 minutes to allow the solution to be fully dissolved and mixed.

[0095] After the solution was cooled naturally to room temperature, it was sealed with a membrane, and then several small holes were punched in the membrane. The solution was placed in a clean, pollution-free environment with no air convection. The reaction temperature was 35°C. After standing for 45 days, several small crystals were formed at the bottom of the container. The crystals continued to grow until there was no obvious change in the size of the crystals. Then, the temperature was lowered to room temperature at a rate of 2°C / day. When the growth was completed, the solution containing the crystals was filtered to obtain a 2.8×1.8×1mm 3 Large transparent crystals of calcium guanidine nitrate.

[0096] Example 14

[0097] According to the reaction formula (4) [C(NH2)3]2CO3+4HNO3+CaCO3→[C(NH2)3]2Ca(NO3)4(H2O)2+2CO2↑, birefringent calcium guanidine nitrate crystals are grown:

[0098] a. Place guanidine carbonate in a 500 mL Teflon beaker and mechanically stir the material with a spatula. Slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80° C. to remove excess water and carbon dioxide gas to obtain colorless crystalline guanidine nitrate. Grind the guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure that all water is removed.

[0099] b. Dissolve the guanidine nitrate and calcium carbonate prepared in step a in deionized water at a molar ratio of 2:1 until completely dissolved, add 10 mL of deionized water, adjust the pH value to 1 with 1 mol / L nitric acid solution, and treat in an ultrasonic bath at 25 ° C for 15 min to fully mix and dissolve;

[0100] c. After the mixed solution in step b is naturally cooled to room temperature, it is placed in a clean, pollution-free environment with no air convection, sealed with a membrane, and several small holes are punched in the membrane, and allowed to stand at room temperature for 30 days;

[0101] d. Wait for the solution in step c to grow crystal particles at the bottom of the container, keep the temperature at 25 ° C for 10 days, wait for the crystals to continue to grow, and the crystal size does not change significantly. The growth is completed, and the solution containing the crystals is filtered to obtain 2.6×1.5×0.8mm 3 Large transparent birefringent crystals of calcium guanidine nitrate.

[0102] Example 15

[0103] According to the reaction formula (4) [C(NH2)3]2CO3+4HNO3+CaCO3→[C(NH2)3]2Ca(NO3)4(H2O)2+2CO2↑, birefringent calcium guanidine nitrate crystals are grown:

[0104] Guanidine carbonate and calcium carbonate were weighed directly in a molar ratio of 1:1 and placed in a conical flask. A 1 mol / L nitric acid solution was added to the flask to adjust the pH of the solution to 1. The solution was treated in an ultrasonic bath at 25°C for 15 minutes to allow the solution to be fully dissolved and mixed.

[0105] After the solution was cooled naturally to room temperature, it was sealed with a membrane, and then several small holes were punched in the membrane. The solution was placed in a clean, pollution-free environment with no air convection. The reaction temperature was 25°C. After standing for 60 days, several small crystals were formed at the bottom of the container. The crystals continued to grow until there was no obvious change in the size of the crystals. Then, the temperature was lowered to room temperature at a rate of 3°C / day. When the growth was completed, the solution containing the crystals was filtered to obtain a 2.9×2.7×1.5mm 3 Large transparent crystals of calcium guanidine nitrate.

[0106] Example 16

[0107] According to the reaction formula (5) [C(NH2)3]2CO3+4HNO3+Ca(OH)2→[C(NH2)3]2Ca(NO3)4(H2O)2+CO2↑+H2O, calcium guanidine nitrate crystals are grown:

[0108] a. Place guanidine carbonate in a 500 mL Teflon beaker and mechanically stir the material with a spatula. Slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80° C. to remove excess water and carbon dioxide gas to obtain white guanidine nitrate. Grind the guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure that all water is removed.

[0109] b. Dissolve the guanidine nitrate and calcium hydroxide prepared in step a in deionized water at a molar ratio of 2:1, add 10 mL of deionized water, adjust the pH value to 1 with 1 mol / L nitric acid solution, and treat in an ultrasonic bath at 25°C for 15 min to fully mix and dissolve;

[0110] c. After the mixed solution in step b is naturally cooled to room temperature, it is sealed with a membrane and several small holes are punched in the membrane or the solution system is directly exposed, placed in a clean, pollution-free environment with no air convection, and allowed to stand at room temperature for 60 days;

[0111] d. After the solution in step c grows crystal particles at the bottom of the container, the solution is kept at a constant temperature of 30°C for 20 days. When the crystals continue to grow and there is no significant change in the size of the crystals, the growth is completed. The solution containing the crystals is filtered to obtain a 2.1×1.5×0.6 mm 3 Large, transparent birefringent crystals of calcium guanidine nitrate.

[0112] Example 17

[0113] According to the reaction formula (5) [C(NH2)3]2CO3+4HNO3+Ca(OH)2→[C(NH2)3]2Ca(NO3)4(H2O)2+CO2↑+H2O, birefringent crystals of calcium guanidine nitrate are grown:

[0114] Directly weigh guanidine carbonate and calcium hydroxide in a molar ratio of 1:1 and place them in a conical flask. Add 1 mol / L nitric acid solution to the flask to adjust the pH of the solution to 1. Treat the solution in an ultrasonic bath at 25°C for 15 minutes to fully dissolve and mix.

[0115] After the solution was naturally cooled to room temperature, it was sealed with a membrane, and then several small holes were punched in the membrane. The solution was placed in a clean, pollution-free environment with no air convection. The reaction temperature was 25°C. After standing for 53 days, several small crystals were formed at the bottom of the container. The temperature was then kept constant at 35°C for 30 days. The crystals continued to grow without any significant change in size. When the crystal size did not change significantly and the growth was completed, the solution containing the crystals was filtered to obtain a 2.7×2.3×1.4mm 3 Large transparent crystals of guanidine calcium nitrate.

[0116] Example 18

[0117] According to reaction formula (6) 2C(NH2)3NO3+2HNO3+CaO+H2O→[C(NH2)3]2Ca(NO3)4(H2O)2, calcium guanidine nitrate crystals are grown:

[0118] a. Place guanidine carbonate in a 500 mL Teflon beaker and mechanically stir the material with a spatula. Slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80° C. to remove excess water and carbon dioxide gas to obtain white guanidine nitrate. Grind the guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure that all water is removed.

[0119] b. Dissolve the guanidine nitrate and calcium oxide prepared in step a in deionized water at a molar ratio of 2:1, add 10 mL of deionized water, adjust the pH value to 1 with 1 mol / L nitric acid solution, and treat in an ultrasonic bath at 25°C for 15 min to fully mix and dissolve;

[0120] c. After the mixed solution in step b is naturally cooled to room temperature, it is sealed with plastic wrap and several small holes are punched in the film. The mixture is placed in a clean, pollution-free environment with no air convection and allowed to stand at room temperature for 35 days.

[0121] d. After the solution in step c grows crystal particles at the bottom of the container, the solution is kept at a constant temperature of 30°C for 15 days. When the crystals continue to grow and there is no significant change in the size of the crystals, the growth is completed. The solution containing the crystals is filtered to obtain a 1.9×1.7×0.6mm 3 Large transparent birefringent crystals of calcium guanidine nitrate.

[0122] Example 19

[0123] According to the reaction formula (7) 2C(NH2)3NO3+2HNO3+CaCO3+H2O→[C(NH2)3]2Ca(NO3)4(H2O)2+CO2↑, calcium guanidine nitrate crystals are grown:

[0124] a. Place guanidine carbonate in a 500 mL Teflon beaker and mechanically stir the material with a spatula. Slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80° C. to remove excess water and carbon dioxide gas to obtain white guanidine nitrate. Grind the guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure that all water is removed.

[0125] b. Dissolve the guanidine nitrate and calcium carbonate prepared in step a in deionized water at a molar ratio of 2:1, add 10 mL of deionized water, adjust the pH value to 1 with 1 mol / L nitric acid solution, and treat in an ultrasonic bath at 25°C for 15 min to fully mix and dissolve;

[0126] c. After the mixed solution in step b is naturally cooled to room temperature, the solution system is directly exposed and placed in a clean, pollution-free environment with no air convection, and allowed to stand at room temperature for 60 days;

[0127] d. Wait for the solution in step c to grow crystal particles at the bottom of the container, then cool it down to room temperature at a rate of 3°C / day. When the crystals continue to grow and there is no significant change in the size of the crystals, the growth is complete. Filter the solution containing the crystals to obtain a 2.8×2.2×1.1mm 3 Large transparent birefringent crystals of calcium guanidine nitrate.

[0128] Example 20

[0129] According to the reaction formula (8) 2C(NH2)3NO3+2HNO3+Ca(OH)2→C(NH2)3]2Ca(NO3)4(H2O)2, calcium guanidine nitrate crystals are grown:

[0130] a. Place guanidine carbonate in a 500 mL Teflon beaker, slowly add 20% excess nitric acid dropwise, and stir with a PET spatula to complete the reaction. Let stand for 10 minutes to obtain a clear solution. Heat the clear solution on a hot plate at 80°C to remove excess water and carbon dioxide gas to obtain colorless crystalline guanidine nitrate. Grind the raw guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure that all water is removed.

[0131] b. Dissolve the guanidine nitrate and calcium hydroxide prepared in step a in deionized water at a molar ratio of 2:1, add 10% excess deionized water, adjust the pH value to 1 with 1 mol / L nitric acid solution, and treat in an ultrasonic bath at 25°C for 15 minutes to fully mix and dissolve;

[0132] c. After the mixed solution in step b was naturally cooled to room temperature, the solution system was directly exposed and placed in a clean, pollution-free environment with no air convection, and allowed to stand at room temperature for 55 days;

[0133] d. Wait for the solution in step c to grow crystal particles at the bottom of the container, then cool it down to room temperature at a rate of 2°C / day. When the crystals continue to grow and there is no significant change in the size of the crystals, the growth is complete. Filter the solution containing the crystals to obtain a 2.6×2×0.9mm 3 Large transparent birefringent crystals of calcium guanidine nitrate.

[0134] Example 21

[0135] Any birefringent calcium guanidine nitrate crystal obtained in Examples 9-20 is used to prepare a wedge-shaped birefringent crystal polarization beam splitter such as Figure 5 As shown, a wedge-shaped birefringent crystal has its optical axis oriented as Figure 5 As shown, a beam of natural light can be separated into two beams of linearly polarized light after passing through the crystal. The greater the birefringence, the farther the two beams can be separated, which facilitates the separation of the light beams.

[0136] Example 22

[0137] Any birefringent crystal of calcium guanidine nitrate obtained in Examples 9-20 is used to prepare an optical isolator such as Figure 6 As shown, an optical isolator is constructed by placing a Faraday rotator that can rotate the polarization plane of an incident light beam by 45 degrees between a pair of birefringent crystal deflectors placed at a 45-degree angle to each other. This allows only forward-propagating light beams to pass through the system, while blocking the reverse-propagating light beams. Figure 6 a means the incident light beam can pass through, Figure 6 b indicates that the reflected light is blocked.

[0138] Example 23

[0139] Any birefringent crystal of calcium guanidine nitrate obtained in Examples 9-20 is used to prepare a beam displacer such as Figure 7 As shown in the figure, the beam displacer is a birefringent crystal that is processed so that its optical axis and the edge form an angle θ, as shown in the figure. Figure 7 As shown in a; when natural light is incident vertically, it can be divided into two linearly polarized lights with vibration directions perpendicular to each other, as shown in Figure 7 As shown in b, they are o light and e light respectively. The greater the birefringence, the farther the two beams of light can be separated, which facilitates the separation of the light beams.

Claims

1. A birefringent calcium guanidine nitrate crystal, characterized in that: The chemical formula of the crystal is [C(NH2)3]2Ca(NO3)4(H2O)2, the molecular weight is 444.33, it belongs to the monoclinic system, and the space group is C 2 / c , the unit cell parameters are a = 20.319(3) Å, b = 6.5717(8) Å, c = 14.2195(16) Å, α = 90°, β = 116.399(5) °, γ = 90°, the unit cell volume is 1700.8(4) Å 3 .

2. A method for preparing birefringent calcium guanidine nitrate crystals as claimed in claim 1, characterized in that The room temperature aqueous solution method was used to grow birefringent calcium guanidine nitrate crystals. The specific operation was carried out according to the following steps: a. Place guanidine carbonate in a 500 mL Teflon beaker and mechanically stir the mixture with a spatula. Slowly add nitric acid dropwise until no bubbles are generated to obtain a clear solution. Heat the clear solution on a hot plate at 80°C to remove excess water and carbon dioxide gas to obtain white or colorless crystalline raw guanidine nitrate. Grind the raw guanidine nitrate and irradiate it under an infrared lamp for 30 minutes to ensure complete removal of water. b. Dissolve the guanidine nitrate and calcium nitrate tetrahydrate prepared in step a in deionized water at a molar ratio of 2:1, add 10 mL of deionized water, adjust the pH value to 1 with 1 mol / L nitric acid solution, and treat in an ultrasonic bath at 25°C for 15 min to fully mix and dissolve; Alternatively, directly weigh guanidine carbonate and calcium nitrate tetrahydrate in a molar ratio of 1:1, place them in a conical flask, add nitric acid solution with a concentration of 1 mol / L, adjust the pH of the solution to 1, and treat it in an ultrasonic bath at 25°C for 15 minutes to fully dissolve and mix them; c. After the mixed solution in step b is naturally cooled to room temperature, it is sealed with plastic wrap and several small holes are punched in the plastic wrap or the solution system is directly exposed, placed in a clean, pollution-free environment with no air convection, and allowed to stand at room temperature for 30-60 days; d. After the solution in step c grows crystal particles at the bottom of the container, the temperature is lowered to room temperature at a rate of 2-3°C / day or maintained at a temperature of 25-35°C for 10-30 days. When the crystals continue to grow and there is no significant change in crystal size, the growth is completed, and the solution containing the crystals is filtered to obtain birefringent crystals of calcium guanidine nitrate.

3. Use of the birefringent calcium guanidine nitrate crystal according to claim 1 in preparing an optical isolator, a circulator, a beam displacer, an optical polarizer or an optical modulator.

4. The use according to claim 3, characterized in that The optical polarizer is a polarizing beam splitter prism.

5. The use according to claim 4, characterized in that The polarization beam splitter prism is a Glan prism, a Wollaston prism or a Rochon prism.

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