Infrared non-linear optical crystal, preparation process and application thereof

Abstract

An infrared non-linear optical crystal has the following molecular formula: A.sub.18X.sub.21Y.sub.6M.sub.48, in which A is Ba, Sr or Pb; X is Zn, Cd or Mn; Y is Ga, In or Al; and M is S, Se or Te. The crystal belongs to trigonal system and has space group R3. The crystal Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 is a type I phase matching non-linear optical material, in a particle size range of 150˜210 μm, its powder frequency doubling intensity and the laser damage threshold are respectively 0.5 times and 28 times those of the commercial material AgGaS.sub.2. Other crystals have the same or similar structure and properties such as optical property. The infrared non-linear optical crystal of the present application has important prospects in military and civilian applications, and can be used in electro-optical countermeasures, resource detection, space antimissile and communications, etc.

Claims

1. An infrared non-linear optical crystal, wherein the crystal has the following molecular formula:
A.sub.18X.sub.21Y.sub.6M.sub.48, wherein A is Ba, Sr or Pb; X is Zn, Cd or Mn; Y is Ga, In or Al; and M is S, Se or Te; and the crystal structure of the infrared non-linear optical crystal belongs to a trigonal system, and is in space group R3.

2. The infrared non-linear optical crystal according to claim 1, having a formula of Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48, Ba.sub.18Zn.sub.21Ga.sub.6Se.sub.48, Ba.sub.18Zn.sub.21Ga.sub.6Te.sub.48, Ba.sub.18Zn.sub.21In.sub.6S.sub.48, Ba.sub.18Zn.sub.21In.sub.6Se.sub.48, Ba.sub.18Zn.sub.21In.sub.6Te.sub.48, Ba.sub.18Zn.sub.21Al.sub.6S.sub.48, Ba.sub.18Zn.sub.21Al.sub.6Se.sub.48, Ba.sub.18Zn.sub.21Al.sub.6Te.sub.48, Ba.sub.18Cd.sub.21Ga.sub.6S.sub.48, Ba.sub.18Cd.sub.21Ga.sub.6Se.sub.48, Ba.sub.18Cd.sub.21Ga.sub.6Te.sub.48, Ba.sub.18Cd.sub.21In.sub.6S.sub.48, Ba.sub.18Cd.sub.21In.sub.6Se.sub.48, Ba.sub.18Cd.sub.21In.sub.6Te.sub.48, Ba.sub.18Cd.sub.21Al.sub.6S.sub.48, Ba.sub.18Cd.sub.21Al.sub.6Se.sub.48, Ba.sub.18Cd.sub.21Al.sub.6Te.sub.48, Ba.sub.18Mn.sub.21Ga.sub.6S.sub.48, Ba.sub.18Mn.sub.21Ga.sub.6Se.sub.48, Ba.sub.18Mn.sub.21Ga.sub.6Te.sub.48, Ba.sub.18Mn.sub.21In.sub.6S.sub.48, Ba.sub.18Mn.sub.21In.sub.6Se.sub.48, Ba.sub.18Mn.sub.21In.sub.6Te.sub.48, Ba.sub.18Mn.sub.21Al.sub.6S.sub.48, Ba.sub.18Mn.sub.21Al.sub.6Se.sub.48, Ba.sub.18Mn.sub.21Al.sub.6Te.sub.48, Sr.sub.18Zn.sub.21Ga.sub.6S.sub.48, Sr.sub.18Zn.sub.21Ga.sub.6Se.sub.48, Sr.sub.18Zn.sub.21Ga.sub.6Te.sub.48, Sr.sub.18Zn.sub.21In.sub.6S.sub.48, Sr.sub.18Zn.sub.21In.sub.6Se.sub.48, Sr.sub.18Zn.sub.21In.sub.6Te.sub.48, Sr.sub.18Zn.sub.21Al.sub.6S.sub.48, Sr.sub.18Zn.sub.21Al.sub.6Se.sub.48, Sr.sub.18Zn.sub.21Al.sub.6Te.sub.48, Sr.sub.18Cd.sub.21Ga.sub.6S.sub.48, Sr.sub.18Cd.sub.21Ga.sub.6Se.sub.48, Sr.sub.18Cd.sub.21Ga.sub.6Te.sub.48, Sr.sub.18Cd.sub.21In.sub.6S.sub.48, Sr.sub.18Cd.sub.21In.sub.6Se.sub.48, Sr.sub.18Cd.sub.21In.sub.6Te.sub.48, Sr.sub.18Cd.sub.21Al.sub.6S.sub.48, Sr.sub.18Cd.sub.21Al.sub.6Se.sub.48, Sr.sub.18Cd.sub.21Al.sub.6Te.sub.48, Sr.sub.18Mn.sub.21Ga.sub.6S.sub.48, Sr.sub.18Mn.sub.21Ga.sub.6Se.sub.48, Sr.sub.18Mn.sub.21Ga.sub.6Te.sub.48, Sr.sub.18Mn.sub.21In.sub.6S.sub.48, Sr.sub.18Mn.sub.21In.sub.6Se.sub.48, Sr.sub.18Mn.sub.21In.sub.6Te.sub.48, Sr.sub.18Mn.sub.21Al.sub.6S.sub.48, Sr.sub.18Mn.sub.21Al.sub.6Se.sub.48, Sr.sub.18Mn.sub.21Al.sub.6Te.sub.48, Pb.sub.18Zn.sub.21Ga.sub.6S.sub.48, Pb.sub.18Zn.sub.21Ga.sub.6Se.sub.48, Pb.sub.18Zn.sub.21Ga.sub.6Te.sub.48, Pb.sub.18Zn.sub.21In.sub.6S.sub.48, Pb.sub.18Zn.sub.21In.sub.6Se.sub.48, Pb.sub.18Zn.sub.21In.sub.6Te.sub.48, Pb.sub.18Zn.sub.21Al.sub.6S.sub.48, Pb.sub.18Zn.sub.21Al.sub.6Se.sub.48, Pb.sub.18Zn.sub.21Al.sub.6Te.sub.48, Pb.sub.18Cd.sub.21Ga.sub.6S.sub.48, Pb.sub.18Cd.sub.21Ga.sub.6Se.sub.48, Pb.sub.18Cd.sub.21Ga.sub.6Te.sub.48, Pb.sub.18Cd.sub.21In.sub.6S.sub.48, Pb.sub.18Cd.sub.21In.sub.6Se.sub.48, Pb.sub.18Cd.sub.21In.sub.6Te.sub.48, Pb.sub.18Cd.sub.21Al.sub.6S.sub.48, Pb.sub.18Cd.sub.21Al.sub.6Se.sub.48, Pb.sub.18Cd.sub.21Al.sub.6Te.sub.48, Pb.sub.18Mn.sub.21Ga.sub.6S.sub.48, Pb.sub.18Mn.sub.21Ga.sub.6Se.sub.48, Pb.sub.18Mn.sub.21Ga.sub.6Te.sub.48, Pb.sub.18Mn.sub.21In.sub.6S.sub.48, Pb.sub.18Mn.sub.21In.sub.6Se.sub.48, Pb.sub.18Mn.sub.21In.sub.6Te.sub.48, Pb.sub.18Mn.sub.21Al.sub.6S.sub.48, Pb.sub.18Mn.sub.21Al.sub.6Se.sub.48, or Pb.sub.18Mn.sub.21Al.sub.6Te.sub.48.

3. The infrared non-linear optical crystal according to claim 2, wherein the formula is Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48, and has a structure of a three-dimensional anionic framework stacked along the c direction thereof a plurality of two-dimensional layers consisting of GaS.sub.4 tetrahedron, Zn.sub.4S.sub.10 T2 super tetrahedron, and Zn.sub.3GaS.sub.10 tetramer having common vertices, and Ba.sup.2+ cations and S.sup.2− anions reside in the framework; wherein each two-dimensional layer is formed by connecting three vertices of GaS.sub.4 tetrahedron parallel to the two-dimensional layer alternately with one Zn.sub.4S.sub.10 T2 super tetrahedron and one Zn.sub.3GaS.sub.10 tetramer, respectively; and wherein the plurality of two-dimensional layers are stacked into the three-dimensional anionic framework via common S atoms shared by the vertex of the GaS.sub.4 tetrahedron (c direction) in one two-dimensional layer and the vertex of the Zn.sub.4S.sub.10 T2 super tetrahedron of the adjacent two-dimensional layer (−c direction).

4. The infrared non-linear optical crystal according to claim 1, wherein the formula is Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48, has a structure of a three-dimensional anionic framework stacked along the c direction thereof a plurality of two-dimensional layers consisting of GaS.sub.4 tetrahedron, Zn.sub.4S.sub.10 T2 super tetrahedron, and Zn.sub.3GaS.sub.10 tetramer having common vertices, and Ba.sup.2+ cations and S.sup.2− anions reside in the framework; wherein each two-dimensional layer is formed by connecting three vertices of GaS.sub.4 tetrahedron parallel to the two-dimensional layer alternately with one Zn.sub.4S.sub.10 T2 super tetrahedron and one Zn.sub.3GaS.sub.10 tetramer, respectively; and wherein the plurality of two-dimensional layers are stacked into the three-dimensional anionic framework via common S atoms shared by the vertex of the GaS.sub.4 tetrahedron (c direction) in one two-dimensional layer and the vertex of the Zn.sub.4S.sub.10 T2 super tetrahedron of the adjacent two-dimensional layer (−c direction).

5. The infrared non-linear crystal of claim 1, having unit cell parameters of a=b=7.5 to 11.5 Å, c=25.0 to 30.0 Å, α=β=90°, γ=120°, and V=1300.0 to 3400.0 Å.sup.3.

6. The infrared non-linear crystal of claim 1, having a formula of Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 and unit cell parameters of a=b=9.8 Å, c=27.1 Å, α=β=90°, γ=120°, and V=2231.8 Å.sup.3.

7. A process for the preparation of the infrared non-linear optical crystal according to claim 1, comprising: placing a raw material comprising compound AM, compound XM, and compound Y.sub.2M.sub.3 under vacuum condition; and preparing the infrared non-linear optical crystal via a high temperature solid phase method, wherein A is Ba, Sr or Pb; X is Zn, Cd or Mn; Y is Ga, In or Al; and M is S, Se or Te, and wherein the molar ratio of AM, XM, and Y.sub.2M.sub.3 in the raw materials is AM:XM:Y.sub.2M.sub.3=18:21:3.

8. The preparation process according to claim 7, further comprising: (1) fully grinding and tableting the raw material, followed by sintering, to obtain a pure phase microcrystalline powder of the infrared non-linear optical crystal material; and (2) annealing the pure phase microcrystalline powder at high temperature to obtain the infrared non-linear optical crystal having a particle size of up to 0.25 mm.

9. The preparation process according to claim 7, comprising: (1) fully grinding and tableting the raw material and then placing under vacuum condition at a temperature of 700 to 1100° C., maintaining the temperature for not less than 100 hours; and decreasing temperature to obtain a pure phase microcrystalline powder; and (2) heating the pure phase microcrystalline powder at 800-1000° C. for not less than 100 hours; and decreasing temperature to obtain the infrared non-linear optical crystal.

10. The preparation process according to claim 7, comprising: (1a) fully grinding and mixing uniformly AM, XM, and Y.sub.2M.sub.3 at a molar ratio of AM:XM:Y.sub.2M.sub.3 of 18:21:3 to obtain the raw material; (1b) tableting the raw material; (1c) placing the tableted raw material in a closed container in a heating device, under vacuum condition, elevating the temperature to 700 to 1100° C. and maintaining the temperature for 100 hours, then decreasing the temperature at a rate of not more than 5° C./hour to 300° C. and stopping heating, naturally cooling to room temperature to obtain a pure phase microcrystalline powder; (2) elevating the temperature of the pure phase microcrystalline powder to 800 to 1000° C. and maintaining the temperature for 100 hours, then decreasing the temperature at a rate of not more than 5° C./hour to 300° C. and stopping heating, naturally cooling to room temperature to obtain the infrared non-linear optical crystal having a particle size in a range of about 0.03 to 0.25 mm, wherein the AM is barium sulfide, the XM is zinc sulfide, and the Y.sub.2M.sub.3 is gallium sulfide.

11. The preparation process according to claim 9, wherein the temperature-decreasing process in step (1) is: programmed decreasing the temperature to 300° C. at a rate of not more than 5° C./hour and then naturally cooling to room temperature to obtain the pure phase microcrystalline powder.

12. The preparation process according to claim 9, wherein the temperature-decreasing process in step (2) is: programmed decreasing the temperature to 300° C. at a rate of not more than 5° C./hour and then naturally cooling to room temperature to obtain the infrared non-linear optical crystal.

13. An infrared detector comprising the infrared non-linear optical crystal according to claim 1.

14. An infrared detector comprising the infrared non-linear optical crystal prepared by the process of claim 7.

15. An infrared laser comprising the infrared non-linear optical crystal according to claim 1.

16. An infrared laser comprising the infrared non-linear optical crystal prepared by the process of claim 7.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram of the structure of the Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 crystal.

(2) FIG. 2 is the powder X-ray diffraction pattern of Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48.

(3) FIG. 3 is the crystal FT-IR spectrum of Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48.

(4) FIG. 4 is the powder experimental energy gap of Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48.

(5) FIG. 5 is the relationship diagram of the change of the powder frequency doubling intensity of Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 with granularity.

(6) FIG. 6 is the relationship diagram of the powder frequency doubling intensity of Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 and that of reference AgGaS.sub.2 (150˜210 μm).

(7) FIG. 7 is the relationship diagram of the powder laser damage threshold of Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 and that of reference AgGaS.sub.2 (150˜210 μm).

(8) FIG. 8 is the fluorescence spectrum of Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48.

EMBODIMENTS

(9) The technical solutions of the present invention are described in detail below by way of exemplary examples. However, these examples should not be construed as limiting the scope of the present invention. All the technologies achieved based on the above contents of the present invention are covered by the protection scope of the present invention.

(10) In the present invention, raw material gallium sulfide is prepared by the boron vulcanization method, and the other two raw materials (barium sulfide and zinc sulfide) are commercially available and are used directly without special treatment.

Example 1

(11) The raw materials barium sulfide, zinc sulfide and gallium sulfide were ground and mixed uniformly according to a molar ratio of barium sulfide:zinc sulfide:gallium sulfide of 18:21:3 to obtain a raw material mixture, followed by tableting, the tableted raw material mixture was placed in a graphite crucible.

(12) The graphite crucible loaded with the raw material mixture was placed in a quartz reaction tube, which was vacuumed to 10.sup.−3 Pa, and sealed by oxyhydrogen flame. The sealed quartz reaction tube was placed into a tube furnace with a temperature controller, heated to 850° C. (i.e., the solid melt temperature), and maintained for at least 100 hours. Then the temperature was decreased at a rate of not more than 5° C./hour to 300° C., followed by stopping heating and naturally cooling to room temperature to obtain pure phase microcrystalline powder of the non-linear optical crystal material.

(13) The quartz tube loaded with the above pure phase microcrystalline powder was put into a tube furnace with a temperature controller, heated to 920° C. and maintained for at least 100 hours, then cooled down to 300° C. at a rate of not more than 5° C./hour, followed by stopping heating and naturally cooling to room temperature, to obtain the non-linear optical crystal material, the crystal material was crystal having a large particle size, which could reach up to 0.25 mm.

(14) Structural characterization of the non-linear optical crystal material obtained in Example 1

(15) The X-ray single crystal diffraction of the crystal material was performed on a Mercury CCD type single crystal diffractometer with Mo target, Kα radiation source (λ=0.07107 nm) and a test temperature of 293K. Its structure was analyzed through Shelxtl97. The results of its crystallographic data are shown in Table 1, and the crystal structure diagram is shown in FIG. 1.

(16) TABLE-US-00001 TABLE 1 Crystallographic data of the sample Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 Crystal Parameters Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 Molecular formula Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 Molecular weight 1934.03 Space group Trigonal (R3) a axis (Å)   9.7679(2) c axis (Å)  27.009(2) α = β  90° γ 120° Volume V (Å.sup.3) 2231.75(9) Density   4.317 Dc (g .Math. cm.sup.−3)

(17) As shown in FIG. 1, the crystal structure of the crystal is mainly a three-dimensional anionic framework stacked along the c direction by two-dimensional layers consisting of GaS.sub.4 tetrahedron, Zn.sub.4S.sub.10 T2 super tetrahedron and Zn.sub.3GaS.sub.10 tetramer via common vertices, and the cation Ba.sup.2+ and the anion S.sup.2− are filled in the framework.

(18) The X-ray powder diffraction phase analysis (XRD) of the non-linear optical crystal obtained in Example 1 was performed on a MiniFlexII type X-ray diffractometer from Rigaku Corporation, with Cu target, and Kα radiation source (λ=0.154184 nm). The powder XRD pattern of the sample and the XRD pattern obtained by fitting of the single crystal diffraction data are shown in FIG. 2. It can be seen from FIG. 2 that the XRD pattern of the sample is consistent with the XRD pattern obtained by fitting of the single crystal diffraction data, indicating that the obtained sample has high crystallinity and purity.

(19) Characterization of optical properties of the non-linear optical crystals obtained in Example 1

(20) The optical properties of the samples were characterized on Nicolet Magna 750 FT-IR infrared spectrometer and PE Lambda 950 UV-visible (near infrared) absorption or diffuse reflectance spectrometer. The results are shown in FIG. 3. It can be seen from FIG. 3 that the powder transmission range of the sample is 0.6 to 25 μm.

(21) The powder experimental energy gap of the sample is shown in FIG. 4. The relationship of the change of the powder frequency doubling intensity of the sample with granularity is shown in FIG. 5. The relationship between the powder frequency doubling intensity of the sample and that of the reference AgGaS.sub.2 (150-210 μm) is shown in FIG. 6. The relationship between the powder laser damage threshold of the sample and that of the reference AgGaS.sub.2 (150˜210 μm) is shown in FIG. 7. The fluorescence property is shown in FIG. 8. The specific values are listed in Table 2.

(22) TABLE-US-00002 TABLE 2 Data of optical properties of sample Data of optical properties Powder Laser frequency damage doubling threshold Light Band intensity*.sup.1 intensity*.sup.2 transmittance gap Sample (mV) (MW/cm.sup.2) range (μm) (eV) Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 260 40.4749 0.6~25 3.5 AgGaS.sub.2 520 1.4416 0.6~23 2.56 *.sup.1The granularity range of the sample and reference AgGaS.sub.2 was 150~210 μm, and the incident laser wavelength was 2050 nm. *.sup.2The granularity range of the sample and reference AgGaS.sub.2 was 150~210 μm, laser wavelength was 1064 nm, working frequency was 1 Hz, pulse width was 10 ns, and laser energy was 1 to 100 mJ, which was adjustable, and the focal length of the lens was f = 20 cm.

(23) The present invention has obtained Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 by a two-step solid-phase synthesis method, and has realized the multi-functionalization of the second-order nonlinearity and the fluorescence property.

Examples 2-7

(24) Examples 2-7 adopted the same preparation process as that in Example 1 except that the raw materials were the compounds shown in Table 3. The prepared crystals were tested to have the same or similar structure and optical properties to those of the Ba.sub.18Zn.sub.21Ga.sub.6S.sub.48 crystal in Example 1.

(25) TABLE-US-00003 TABLE 3 Raw materials of Examples 2-7 AM XM Y.sub.2M.sub.3 Example 2 SrS ZnS Ga.sub.2S.sub.3 Example 3 PbS ZnS Ga.sub.2S.sub.3 Example 4 BaS CdS Ga.sub.2S.sub.3 Example 5 BaS ZnS In.sub.2S.sub.3 Example 6 SrS CdS Ga.sub.2S.sub.3 Example 7 BaSe ZnSe Ga.sub.2Se.sub.3

(26) The above descriptions are merely some examples of the present invention, and are not intended to limit the present invention in any form. Although the present invention is disclosed by the above preferred examples, those examples are not intended to limit the present invention. Changes or modifications made by any one skilled in the art using the technical contents disclosed above without departing from the technical solutions of the present invention are all equivalent implementation examples and fall within the scope of the technical solutions.