A nonlinear optical crystal bismuth iodide selenite and its preparation method and application

Abstract

The present invention discloses a nonlinear optical crystal bismuth iodide selenite, a preparation method thereof and an application thereof. The nonlinear optical crystal bismuth iodide selenite has a chemical formula of BiSeIO6, is an orthorhombic crystal system, has a space group of Pna2(1), and has unit cell parameters of a=7.115 Å, b=11.335 Å, c=6.717 Å, and V=541.67 Å. 3 A bismuth source, an iodine source, and a selenium source are mixed in a molar ratio of bismuth to iodine to selenium of 1-1.2:1-1.2:1-1.2, and subjected to a hydrothermal reaction at 150-250°C for at least 24 hours to obtain a nonlinear optical crystal, bismuth iodide selenite. The nonlinear optical crystal bismuth iodide selenite of this invention is used in laser frequency conversion devices. It exhibits a strong frequency-doubled effect. Under 1064nm pulsed laser pumping, the powder frequency-doubled intensity generated is six times that of potassium dihydrogen phosphate (KDP) under the same conditions. It also achieves type I phase matching, facilitating the debugging of laser devices and efficient laser frequency conversion applications.

Description

Technical Field

[0001] The present invention belongs to the field of nonlinear optical crystal materials, and in particular relates to a nonlinear optical crystal bismuth iodide selenite and a preparation method and application thereof. Background Art

[0002] Laser frequency conversion and tuning technologies based on nonlinear optical crystals are primarily achieved through nonlinear optical processes such as frequency doubling, sum frequency multiplication, difference frequency multiplication, optical parametric amplification, and optical parametric oscillation. These technologies have important and widespread applications in spectral analysis, laser processing, laser communications, laser medical treatment, and laser displays. Currently, the development of nonlinear optical crystals for the visible light band is relatively mature, with widely used crystals including BaB2O4 (BBO), LiB3O5 (LBO), and KTiOPO4 (KTP). Meanwhile, practical nonlinear optical crystals for the infrared band are relatively limited, primarily AgGaS2 (AGS) and ZnGeP2 (ZGP). These crystals offer a wide infrared transmission range and large frequency doubling coefficients. However, their small optical band gaps and large optical absorption coefficients limit their application in the ultraviolet and visible light bands.

[0003] The current demand for multifunctionality, miniaturization and integration of optoelectronic functional devices has prompted people to urgently develop nonlinear optical crystals with a wide transmittance range from ultraviolet to infrared bands. Summary of the Invention

[0004] Aiming at the problem of small light transmission range of nonlinear optical crystals in the prior art, the present invention provides a nonlinear optical crystal bismuth iodide selenite and its preparation method and application, using Bi containing lone pair electron stereochemical activity 3+ 、Se 4+ and I 5+ As the central cation, a new non-central polarity nonlinear optical crystal material bismuth iodide selenite with a three-dimensional stereoscopic framework structure was collaboratively constructed, which broadened the transmittance range of its application in nonlinear optical crystals and was used in laser processing, spectral analysis, communication, medical treatment and other fields.

[0005] The present invention is achieved through the following technical solutions:

[0006] A nonlinear optical crystal of bismuth iodide selenite, characterized in that its chemical formula is BiSeIO6, it is an orthorhombic crystal system, the space group is Pna2(1), and the unit cell parameters are a = 7.115 Å, b = 11.335 Å, c = 6.717 Å, and V = 541.67 Å. 3 .

[0007] In the present invention, the preparation method of the nonlinear optical crystal bismuth iodide selenite is as follows: a bismuth source, an iodine source, and a selenium source are mixed in a molar ratio of bismuth element, iodine element, and selenium element of 1-1.2:1-1.2:1-1.2, and the mixture is subjected to a hydrothermal reaction at 150-250° C. for more than 24 hours to obtain the nonlinear optical crystal bismuth iodide selenite.

[0008] Furthermore, the hydrothermal reaction time is 24 to 72 hours.

[0009] Furthermore, the bismuth source is one or more of bismuth nitrate, bismuth oxide, bismuth chloride, bismuth fluoride, and bismuth carbonate.

[0010] Furthermore, the selenium source is one or more of selenium dioxide, selenous acid, sodium selenite, and potassium selenite.

[0011] Furthermore, the iodine source is one or more of iodine pentoxide, iodic acid, sodium iodate, and potassium iodate.

[0012] Furthermore, the hydrothermal reaction solvent is water or dilute nitric acid.

[0013] Furthermore, the concentration of the dilute nitric acid is 3-10%.

[0014] The present invention describes the application of the nonlinear optical crystal bismuth iodide selenite in laser frequency conversion devices. The crystal exhibits a strong frequency-doubled effect. Under 1064nm pulsed laser pumping, the powder's frequency-doubled intensity is six times that of potassium dihydrogen phosphate (KDP) under the same conditions. Furthermore, it can achieve type I phase matching, facilitating the debugging of laser devices and efficient laser frequency conversion applications.

[0015] The present invention proposes a bismuth iodide selenite crystal material, the crystal structure of which is described as follows: BiO7 asymmetric polyhedral coordination units are connected by oxygen atoms in a corner-sharing manner to form a zigzag one-dimensional Bi-O atomic chain skeleton, and the surrounding adjacent Bi-O atomic chain skeleton bridges are further bridged by SeO3 and IO3 coordination units with pyramidal configurations in a vertex-sharing manner, forming a three-dimensional crystal structure in which the electric dipole moments of the three asymmetric functional groups of BiO7, SeO3 and IO3 are arranged in an orderly manner roughly along the crystal axis c, thereby greatly enhancing the frequency doubling effect of the crystal.

[0016] Beneficial effects

[0017] (1) The bismuth iodide selenite crystal material prepared in the present invention has the advantages of low reaction temperature and simple and convenient crystal growth method. At the same time, the grown crystal has stable physical and chemical properties, does not deliquesce in air, and does not decompose below 390°C, which is convenient for high-power laser frequency conversion applications;

[0018] (2) The bismuth iodide selenite crystal material prepared in the present invention has a strong frequency-doubled effect. The frequency-doubled intensity of the powder generated under 1064nm pulsed laser pumping is 6 times that of potassium dihydrogen phosphate (KDP) under the same conditions, and can achieve type I phase matching, which is beneficial to the debugging of laser devices and high-efficiency laser frequency conversion applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the crystal structure of bismuth iodide selenite.

[0020] Figure 2 This is the powder X-ray diffraction pattern of bismuth iodide selenite.

[0021] Figure 3 This is the UV-visible-near-infrared absorption spectrum of bismuth iodide selenite.

[0022] Figure 4 This is a comparison of the frequency doubling effect of bismuth iodide selenite and KDP under 1064nm pulse laser pumping. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. The embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1

[0025] Weigh 2 mmol of bismuth nitrate, 2 mmol of selenium dioxide, and 1 mmol of iodine pentoxide into a polytetrafluoroethylene-lined reactor, add 2 ml of water and stir evenly, seal in a stainless steel jacket, and heat to 180°C in an oven for 48 h. Cool to room temperature, remove the reaction product, and rinse with deionized water to obtain colorless iodine-pure bismuth selenite crystals.

[0026] Example 2

[0027] 2 mmol of bismuth nitrate, 2.2 mmol of sodium selenite, and 2.2 mmol of iodic acid were weighed and placed in a polytetrafluoroethylene-lined reactor. 4 ml of water was added and mixed evenly. The mixture was sealed in a stainless steel reactor and heated to 200°C in an oven for 72 h. The reaction product was cooled to room temperature, the reaction product was removed, and washed with deionized water to obtain colorless iodine-pure bismuth selenite crystals.

[0028] Example 3

[0029] 1 mmol of bismuth oxide, 2.2 mmol of selenious acid, and 1.1 mmol of iodine pentoxide were weighed and placed in a polytetrafluoroethylene-lined reactor. 2 ml of 5% dilute nitric acid was added and mixed evenly. The mixture was sealed in a stainless steel reactor and heated to 180°C in an oven for 72 h. The reaction product was cooled to room temperature, removed, and washed with deionized water to obtain colorless iodine-pure bismuth selenite crystals.

[0030] Example 4

[0031] 1 mmol of bismuth oxide, 2.1 mmol of selenium dioxide, and 2.2 mmol of iodic acid were weighed and placed in a polytetrafluoroethylene-lined reactor. 4 ml of 5% dilute nitric acid was added and mixed evenly. The mixture was sealed in a stainless steel reactor and heated to 180°C in an oven for 72 h. The reaction product was cooled to room temperature, removed, and washed with deionized water to obtain colorless pure crystalline bismuth iodide selenite.

[0032] Sample analysis

[0033] (1) The bismuth iodide selenite single crystals prepared in Examples 1 to 4 above were subjected to X-ray diffraction tests. Bismuth iodide selenite single crystals of suitable size were selected and mounted on Bruker's APEX II CCD single crystal diffractometer for room temperature single crystal diffraction tests. The results showed that the parameters of the single crystals synthesized in the above examples were the same, all of which were bismuth iodide selenite, with the crystal structure shown in FIG. Figure 1 As shown, the chemical formula of bismuth iodide selenite is BiSeIO6, which is an orthorhombic crystal system with a space group of Pna2(1). The unit cell parameters are a = 7.115(4)Å, b = 11.335(8)Å, c = 6.717(4)Å, and V = 541.67(6)Å. 3 ;

[0034] Crystal structure: The BiO7 asymmetric polyhedral coordination units are connected by oxygen atoms in a corner-sharing manner to form a zigzag one-dimensional Bi-O atomic chain skeleton. The surrounding adjacent Bi-O atomic chain skeleton bridges are further bridged by the pyramid-shaped SeO3 and IO3 coordination units in a vertex-sharing manner, forming a three-dimensional crystal structure in which the electric dipole moments of the three asymmetric functional groups of BiO7, SeO3 and IO3 are arranged in an orderly manner roughly along the crystal axis c direction.

[0035] (2) The powder X-ray diffraction of the bismuth iodide selenite synthesized in Example 1 was performed using a PANalytical X'pert3 powder diffractometer, and the pattern was consistent with the pattern simulated by the single crystal test structure, indicating that the synthesized sample was a bismuth iodide selenite crystal. The powder diffraction pattern of bismuth iodide selenite is as follows: Figure 2 shown.

[0036] (3) The absorption spectrum of the bismuth iodide selenite synthesized in Example 1 was analyzed using a Lambda 1050 UV-Vis-NIR spectrophotometer from PerkinElmer. The results showed that the bismuth iodide selenite crystals had a wide absorption band gap of 3.5 eV and a UV absorption cutoff edge of 350 nm at room temperature. Figure 3 shown.

[0037] (4) Using a 1064 nm pulsed laser as a pump source to irradiate the bismuth iodide selenite crystals in each embodiment, green doubled frequency light of comparable brightness was generated. The samples synthesized in Example 1 were divided into seven groups according to particle size: 26-48, 48-75, 75-100, 100-150, 150-180, 180-250, and 250-315 μm. The doubled frequency signal intensity of the powder samples was detected by a photomultiplier tube and compared with the KDP sample. The result showed that the doubled frequency effect of the sample was 6 times that of KDP, and type I phase matching could be achieved, as shown in Figure 4. Figure 4 shown.

Claims

1. A nonlinear optical crystal bismuth iodide selenite, characterized in that: Its chemical formula is BiSeIO6, it is an orthorhombic crystal with a space group of Pna2(1), and the unit cell parameters are a = 7.115 Å, b = 11.335 Å, c = 6.717 Å, and V = 541.67 Å. 3 .

2. A method for preparing the nonlinear optical crystal bismuth iodide selenite according to claim 1, characterized in that: A bismuth source, an iodine source, and a selenium source are mixed in a molar ratio of bismuth element, iodine element, and selenium element of 1-1.2:1-1.2:1-1.2, and subjected to a hydrothermal reaction at 150-250° C. for more than 24 hours to obtain a nonlinear optical crystal bismuth iodide selenite.

3. The preparation method according to claim 2, characterized in that The hydrothermal reaction time is 24 to 72 hours.

4. The preparation method according to claim 2, characterized in that The bismuth source is one or more of bismuth nitrate, bismuth oxide, bismuth chloride, bismuth fluoride and bismuth carbonate.

5. The preparation method according to claim 2, characterized in that The selenium source is one or more of selenium dioxide, selenous acid, sodium selenite and potassium selenite.

6. The preparation method according to claim 2, characterized in that The iodine source is one or more of iodine pentoxide, iodic acid, sodium iodate and potassium iodate.

7. The preparation method according to claim 2, characterized in that The hydrothermal reaction solvent is water or dilute nitric acid.

8. The preparation method according to claim 7, characterized in that The concentration of the dilute nitric acid is 3-10%.

9. Use of the nonlinear optical crystal bismuth iodide selenite according to claim 1 in a laser frequency conversion device.

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