Compound guanidine calcium nitrate, guanidine calcium nitrate birefringent crystal, preparation method and application

Abstract

The invention provides a compound guanidine calcium nitrate, a guanidine calcium nitrate birefringent crystal and a preparation method and application, the chemical formula of the compound is [C (NH2) 3] 2Ca (NO3) 4 (H2O) 2, the molecular weight is 444.33, the compound is prepared by a solvothermal method, the chemical formula of the crystal is [C (NH2) 3] 2Ca (NO3) 4 (H2O) 2, the molecular weight is 444.33, the crystal belongs to a monoclinic system, the space group is C2 / c, the cell parameters are as follows: a = 20.319 (3), b = 6.5717 (8), c = 14.2195 (16), alpha = 90 degrees, beta = 116.399 (5) degrees, gamma = 90 degrees, and the unit cell volume is 1700.8 (4) 3. The light transmission range of the optical fiber is 281-1600 nm, and the birefringence of the optical fiber is 0.152 (1064 nm)-0.23 (281 nm). The crystal is grown by adopting a room-temperature aqueous solution method, and the obtained birefringent crystal is moderate in mechanical hardness, easy to cut, polish and store, simple in growth condition and easy to grow; the product is insoluble in water, does not deliquesce, and is stable in air; the transparent range and the birefringence are relatively large; the method can be used for manufacturing polarization beam splitting prisms, phase delay devices and electro-optical modulation devices.

Description

Technical Field

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

[0002] Birefringence refers to the phenomenon that one incident light produces two refracted light rays. The fundamental reason for this phenomenon is the anisotropy of the crystal material. The law of refraction is generally only applicable to isotropic media. For anisotropic crystals, under normal circumstances, at least one of the two refracted light waves produced by birefringence does not satisfy the law of refraction. Different directions of incident light, different crystal structures and spatial orientations will result in different birefringence properties. Due to birefringence, a beam of natural light will be decomposed into two mutually offset but parallel transmitted light waves after passing through a parallel plate made of a certain anisotropic crystal, resulting in mutually offset double refracted images. Then this type of crystal is called a birefringent crystal. The birefringence property of the crystal is an important optical parameter of the optoelectronic functional crystal material. By utilizing the characteristics of birefringent crystals, birefringent crystals have become key materials for making optical components such as optical isolators, circulators, beam shifters, optical polarizers and optical modulators.

[0003] Birefringent optical crystals have important application value in many fields, such as scientific research, transportation, national defense, and industry. With the rapid development of laser industry and career, it is extremely urgent to find a new birefringent material with good performance. Commonly used birefringent materials are yttrium vanadate, barium metaborate, lithium niobate, calcite, etc. However, these birefringent materials have shortcomings: YVO4 is an artificial birefringent crystal with good performance, but due to the high melting point of YVO4, it must be pulled and grown in an iridium crucible, and the growth atmosphere is a weak oxygen atmosphere, so there is a problem of iridium valence during growth, which makes the quality of the crystal decrease and it is not easy to obtain high-quality crystals; α-BaB2O4 is easy to crack during the crystal growth process due to the solid-state phase transition; LiNbO3 crystals are easy to obtain large-sized crystals, but the birefringence is too small; Calcite crystals, which mainly exist in natural form, are difficult to synthesize artificially, are generally small in size, and have a high impurity content, which cannot meet the requirements of large-size optical polarizing elements, and are easy to dissociate, difficult to process, and have 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-size 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 a birefringent calcium guanidine nitrate crystal, 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, 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

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

[0009] Another object of the present invention is to provide the 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 displacers, optical polarizers and optical modulators.

[0010] The compound of the invention, calcium guanidine nitrate, 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 solvothermal method, and the specific operation is carried out according to the following steps:

[0012] a. Place guanidine carbonate in a 500 mL Teflon beaker, stir the material mechanically with a spatula, slowly add nitric acid until no bubbles are generated to obtain a clear solution, heat the clear solution on a heating plate at 80° C., remove excess water and carbon dioxide gas, and obtain a white or colorless crystalline raw material guanidine nitrate. Grind the raw material 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 are placed in a polytetrafluoroethylene liner of a hydrothermal reactor in a molar ratio of 2:1, the materials are mechanically stirred with a medicine spoon, and then 2 mL of deionized water is added. The liner is then encapsulated into a stainless steel shell and placed in an electric constant temperature forced air drying oven for heating reaction. The electric constant temperature forced air drying oven is 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 calcium guanidine nitrate crystal, 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, 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, stir the material mechanically with a spatula, slowly add nitric acid until no bubbles are generated to obtain a clear solution, heat the clear solution on a heating plate at 80° C., remove excess water and carbon dioxide gas, and obtain a white or colorless crystalline raw material guanidine nitrate. Grind the raw material 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] Or directly weigh guanidine carbonate and calcium nitrate tetrahydrate in a molar ratio of 1:1, put them into 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 wave at a temperature of 25°C for 15 minutes to fully dissolve and mix them;

[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 left to stand at room temperature for 30-60 days;

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

[0021] The calcium guanidine 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 crystal of the present invention adopts a solvothermal method to synthesize the compound, and adopts a room temperature aqueous solution method to grow the birefringent calcium guanidine nitrate crystal. 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 281-1600nm, and a birefringence index between 0.152 (1064nm) and 0.23 (281nm).

[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 is between 0.152 (1064nm) and 0.23 (281nm). The crystal is easy to grow, cut, grind, polish and store; it is grown by room temperature aqueous solution method. The obtained crystal is stable in air. It can be used to make polarization beam splitting prisms such as Glan prism, Wollaston prism, Rochon prism or beam splitting polarizer, and has important applications in the fields of 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;

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

[0037] Figure 3 It is the UV-visible transmission and crystal photograph of the [C(NH2)3]2Ca(NO3)4(H2O)2 crystal of the present invention;

[0038] Figure 4 It is the birefringence calculation curve diagram of [C(NH2)3]2Ca(NO3)4(H2O)2 of the present invention;

[0039] Figure 5 Schematic diagram of the wedge-shaped birefringent crystal polarization beam splitter of the present invention, wherein 1 is incident light, 2 is o light, 3 is e light, 4 is the optical axis, and 5 is 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 guanidine calcium nitrate [C(NH2)3]2Ca(NO3)4(H2O)2 birefringent crystal, 6 is the light transmission direction, and 7 is the optical axis plane. DETAILED DESCRIPTION

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

[0043] Example 1

[0044] According to 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 polytetrafluoroethylene liner of a 23 mL hydrothermal reactor at a molar ratio of 1:1, mechanically stirred with a medicine spoon, and nitric acid was slowly added dropwise until no bubbles were generated to obtain a clear solution. 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.

[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, stir the material mechanically with a spatula, and slowly add nitric acid until no bubbles are generated to obtain a clear solution. Heat the clear solution on a heating 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 moisture is removed;

[0049] b. Place the guanidine nitrate prepared in step a and calcium nitrate tetrahydrate in a molar ratio of 2:1 in a polytetrafluoroethylene liner of a hydrothermal reactor, and stir the materials mechanically with a medicine spoon. After fully mixing, encapsulate the liner into a stainless steel shell, place it in an electric constant temperature forced air drying oven for heating reaction, heat the electric constant temperature forced air drying oven to 170° C. for 3 hours, keep warm for 4320 minutes, and then cool to room temperature for 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 polytetrafluoroethylene liner of a 23 mL hydrothermal reactor at a molar ratio of 1:1, mechanically stirred with a medicine spoon, and nitric acid was slowly added dropwise until no bubbles were generated to obtain a clear solution. 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.

[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 23mL hydrothermal reactor, stirring mechanically with a spatula, and slowly adding nitric acid until no bubbles are generated to obtain a clear solution. 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.

[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 polytetrafluoroethylene liner of a 23 mL hydrothermal reactor at a molar ratio of 1:1, mechanically stirred with a medicine spoon, and nitric acid was slowly added dropwise until no bubbles were generated to obtain a clear solution. 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.

[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, stir the material mechanically with a spatula, and slowly add nitric acid until no bubbles are generated to obtain a clear solution. Heat the clear solution on a heating 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 moisture is removed;

[0061] b. Place the guanidine nitrate and calcium oxide prepared in step a in a polytetrafluoroethylene liner of a hydrothermal reactor at a molar ratio of 2:1, stir the materials mechanically with a medicine spoon, and add nitric acid dropwise at a molar ratio of nitric acid to calcium oxide of 2:1. After fully mixing, encapsulate the liner into a stainless steel shell, place it in an electric constant temperature blast drying oven for heating reaction, heat the electric constant temperature blast drying oven to 170°C for 3 hours, keep warm 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, stir the material mechanically with a spatula, and slowly add nitric acid until no bubbles are generated to obtain a clear solution. Heat the clear solution on a heating 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 moisture is removed;

[0065] b. The guanidine nitrate and calcium carbonate prepared in step a are placed in a polytetrafluoroethylene liner of a hydrothermal reactor in a molar ratio of 2:1, the materials are mechanically stirred with a medicine spoon, and a nitric acid solution is added dropwise until no bubbles are generated, and then the liner is encapsulated in a stainless steel shell and placed in an electric constant temperature forced air drying oven for heating reaction, and the electric constant temperature forced air drying oven is 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, stir the material mechanically with a spatula, and slowly add nitric acid until no bubbles are generated to obtain a clear solution. Heat the clear solution on a heating 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 moisture is removed;

[0069] b. Place the guanidine nitrate and calcium hydroxide prepared in step a in a polytetrafluoroethylene liner of a hydrothermal reactor at a molar ratio of 2:1, stir the materials mechanically with a medicine spoon, and add nitric acid dropwise at a molar ratio of nitric acid to calcium hydroxide of 2:1. After fully mixing, encapsulate the liner into a stainless steel shell, place it in an electric constant temperature blast drying oven for heating reaction, heat the electric constant temperature blast drying oven to 170°C for 3 hours, keep warm 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 crystals of calcium guanidine nitrate are grown:

[0072] a. Place guanidine carbonate in a 500 mL Teflon beaker, stir the material mechanically with a spatula, slowly add nitric acid until no bubbles are generated to obtain a clear solution, heat the clear solution on a heating 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 they are 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 film, and several small holes are pierced in the film, and left 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. Wait for the crystals to continue to grow, then cool down to room temperature at a rate of 2°C / day. Keep the temperature constant for 10 days. When the growth is complete, filter the solution containing the crystals to obtain a 3.2×2.5×1.2 mm 3 Large size 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 crystals of calcium guanidine nitrate are grown:

[0078] Guanidine carbonate and calcium nitrate tetrahydrate were weighed directly at a molar ratio of 1:1 and placed in a conical flask, 1 mol / L nitric acid solution was added, the pH of the solution was adjusted to 1, and the solution was treated in an ultrasonic wave at a temperature of 25°C for 15 minutes to fully dissolve and mix;

[0079] After the solution was naturally cooled to room temperature, it was sealed with a membrane, and then several small holes were pierced 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 smaller 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 3×2×2.2mm 3 Large size transparent birefringent crystals of calcium guanidine nitrate.

[0080] Embodiment 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, stir the material mechanically with a spatula, slowly add nitric acid until no bubbles are generated to obtain a clear solution, heat the clear solution on a heating plate at 80° C., remove excess water and carbon dioxide gas, and 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 they are 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 pierced in the film or the solution system is directly exposed, and left 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 2×1.2×1mm 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 crystals of calcium guanidine nitrate are grown:

[0088] a. Place guanidine carbonate in a 500 mL Teflon beaker, stir the material mechanically with a spatula, slowly add nitric acid until no bubbles are generated to obtain a clear solution, heat the clear solution on a heating 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, 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 pierced in the membrane or the solution system is directly exposed, and left 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 there is no significant change in the size of the crystals, then cool down to room temperature at a rate of 3°C / day, filter the solution containing the crystals, and obtain 3×2.2×1 mm 3 Large size transparent birefringent calcium guanidine nitrate crystals.

[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] Directly weigh guanidine carbonate and calcium oxide at a molar ratio of 1:1 and put them into a conical flask, add 1 mol / L nitric acid solution into the flask, adjust the pH of the solution to 1, and treat it in an ultrasonic wave at a temperature of 25°C for 15 minutes to fully dissolve and mix them;

[0095] After the solution was naturally cooled to room temperature, it was sealed with a membrane, and then several small holes were pierced 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 smaller 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 finished, the solution containing the crystals was filtered to obtain 2.8×1.8×1mm 3 Large transparent crystals of calcium guanidine nitrate.

[0096] Embodiment 14

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

[0098] a. Place guanidine carbonate in a 500 mL Teflon beaker, stir the material mechanically with a spatula, slowly add nitric acid until no bubbles are generated to obtain a clear solution, heat the clear solution on a heating 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 they are 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 film, and several small holes are pierced in the film, and left 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 has no obvious change. 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] Embodiment 15

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

[0104] Directly weigh guanidine carbonate and calcium carbonate at a molar ratio of 1:1 and put them into a conical flask, add 1 mol / L nitric acid solution into the flask, adjust the pH of the solution to 1, and treat it in an ultrasonic wave at a temperature of 25°C for 15 minutes to fully dissolve and mix them;

[0105] After the solution was naturally cooled to room temperature, it was sealed with a membrane, and then several small holes were pierced 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 smaller 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. The growth was completed, and 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, stir the material mechanically with a spatula, slowly add nitric acid until no bubbles are generated to obtain a clear solution, heat the clear solution on a heating 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 pierced in the membrane or the solution system is directly exposed, placed in a clean, pollution-free environment with no air convection, and left to stand at room temperature for 60 days;

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

[0112] Embodiment 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, put them into a conical flask, add nitric acid solution with a concentration of 1 mol / L into the flask, adjust the pH of the solution to 1, and treat it in an ultrasonic wave at a temperature of 25°C for 15 minutes to fully dissolve and mix them;

[0115] After the solution was naturally cooled to room temperature, it was sealed with a membrane, and then several small holes were pierced 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 smaller 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 obvious changes in size. Until the crystal size did not change significantly and the growth was completed, the solution containing the crystals was filtered to obtain 2.7×2.3×1.4mm 3 Large transparent crystals of calcium guanidine nitrate.

[0116] Embodiment 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, stir the material mechanically with a spatula, slowly add nitric acid until no bubbles are generated to obtain a clear solution, heat the clear solution on a heating 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 pierced in the film. It is placed in a clean, pollution-free environment with no air convection, and left to stand at room temperature for 35 days;

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

[0122] Embodiment 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, stir the material mechanically with a spatula, slowly add nitric acid until no bubbles are generated to obtain a clear solution, heat the clear solution on a heating 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 2.8×2.2×1.1 mm 3 Large transparent birefringent crystals of calcium guanidine nitrate.

[0128] Embodiment 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 drop 20% excess nitric acid, and stir with a PET spoon to complete the reaction. Let stand for 10 minutes to obtain a clear solution. Heat the clear solution on a heating 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 min to fully mix and dissolve;

[0132] 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 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, and the solution containing the crystals is filtered to obtain a 2.6×2×0.9mm 3 Large transparent birefringent crystals of calcium guanidine nitrate.

[0134] Embodiment 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 of light can be separated, making it easier to separate the beams.

[0136] Embodiment 22

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

[0138] Embodiment 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 processes a birefringent crystal so that its optical axis makes an angle θ with the edge, as shown in 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, such as Figure 7 As shown in b, they are o light and e light respectively. The greater the birefringence, the farther the two light beams can be separated, making it easier to separate the light beams.

Claims

1. A compound guanidine calcium nitrate, characterized in that The compound has the chemical formula [C(NH2)3]2Ca(NO3)4(H2O)2, a molecular weight of 444.33, and is prepared by a solvothermal method.

2. A method for preparing the compound guanidine calcium nitrate as claimed in claim 1, characterized in that The solvent thermal method was used for preparation, and the specific operation was carried out according to the following steps: a. Place guanidine carbonate in a 500 mL Teflon beaker, stir the material mechanically with a spatula, slowly add nitric acid until no bubbles are generated to obtain a clear solution, heat the clear solution on a heating 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; b. The guanidine nitrate prepared in step a and calcium nitrate tetrahydrate are placed in a polytetrafluoroethylene liner of a hydrothermal reactor at a molar ratio of 2:

1. The materials are mechanically stirred with a medicine spoon, and then 2 mL of deionized water is added. The liner is then encapsulated in a stainless steel shell and placed in an electric constant temperature forced air drying oven for heating reaction. The electric constant temperature forced air drying oven is 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.

3. A calcium guanidine nitrate birefringent 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°, unit cell volume is 1700.8(4) Å 3 .

4. A method for preparing a calcium guanidine nitrate birefringent crystal as claimed in claim 3, 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, stir the material mechanically with a spatula, slowly add nitric acid until no more bubbles are generated to obtain a clear solution, heat the clear solution on a heating 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; 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; Or directly weigh guanidine carbonate and calcium nitrate tetrahydrate in a molar ratio of 1:1, put them into 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 wave at a temperature of 25°C for 15 min 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 left to stand at room temperature for 30-60 days; d. Wait for the solution in step c to grow crystal particles at the bottom of the container, then cool the temperature to room temperature at a rate of 2-3°C / day or keep the temperature constant at 25-35°C for 10-30 days. When the crystals continue to grow and there is no obvious change in the size of the crystals, the growth is completed, and the solution containing the crystals is filtered to obtain birefringent calcium guanidine nitrate crystals.

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

6. The use according to claim 5, characterized in that The optical polarizer is a polarizing beam splitter prism.

7. The use according to claim 6, characterized in that The polarization beam splitter prism is a Glan prism, a Wollaston prism or a Rochon prism.

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