CN1611642A

CN1611642A - Non-linear optical crystal material potassium pentavanadate

Info

Publication number: CN1611642A
Application number: CN 200310103797
Authority: CN
Inventors: 李国辉; 苏根博; 李征东; 庄欣欣; 贺友平
Original assignee: Fujian Institute of Research on the Structure of Matter of CAS
Current assignee: Fujian Institute of Research on the Structure of Matter of CAS
Priority date: 2003-10-30
Filing date: 2003-10-30
Publication date: 2005-05-04
Anticipated expiration: 2023-10-30
Also published as: CN1332076C

Abstract

This is about penta-potassium vanadate, a nonlinfringe optical crystal material, belonging to the field of optics and artificial crystals materials. The molecular formula of this crystal is K3V5O14, molecular weight 596.06, belonging to the trigonal system, the color of this crystal is dark red and hard to be dissolved in water but slightly dissolved in acid. Its birefringent ratio will be 0.67 and optic walk-off angle is 17.44deg. When using analytically pure K2CO5 and V2O5(99.9%) as raw materials, its mol ratio is 1:1-1:1.5. After they are ground and mixed, they are put in the platinum crucible and heated to 750-760 deg.C, its temperature-rising rate is 2-4deg.C/min. After its constant temperature is kept 1-2 hours, it should be naturally cooled down to 200deg.C and taken out from the Pt crucible into the dryer. When it is cooled to the room-temperature,it will be taken out. The crystals are used for nonlinfringe optical devices of medium long infrared region.

Description

Non-linear optical crystal material potassium pentavanadate

The invention belongs to the field of optical and artificial lens materials.

Background art non-linear optical (NLO) functional crystal material has important application background in the field of laser frequency modulation technology, and excellent NLO crystal materials (barium metaborate BBO, lithium triborate LBO, lithium triborate B, B,Potassium titanyl phosphate (KTP), Lithium Niobate (LN), potassium tantalate (KT), strontium barium niobate, etc.) can be selectively applied and developed. The light-transmitting wave band of the crystals is generally only 2-5 mu m, and the crystals cannot be used as NLO materials of middle and far infrared rays. The compounds currently studied for infrared NLO materials are mostly concentrated on semiconductor type crystals (Te, CdSe, AgGaS)₂、Tl₃AsS₃Etc.) and is characterized in that the transmission wave band is deep into the infrared region, the nonlinear coefficient is high, the defects are small crystal size, poor optical quality and low damage threshold, so that the exploration of novel middle and far infrared NLO materials is a hot research subject to be solved in the world at present. Oxoacids MO of sub-five elements M (M ═ V, Nb, Ta)^-3Or MO^-4Salts, which have greater deformability in their anionic groups and localization of the electron cloud distribution, cause strong macroscopic nonlinear effects due to strong molecular repolarization rates in optical frequency electric fields, as described above in niobium (tantalate) Crystal materials with large nonlinear coefficients have been studied, Mikio Miguchi et al (Journal of Crystal Growth 216(2000)322-_II-LiVO₄The single crystal (orthorhombic, space group Pmn21) has a large Second Harmonic Generation (SHG) effect similar to that of an LN crystal. We searched for potassium pentavanadate (K)₃V₅O₁₄) The crystal structure (see fig. 1) is a non-symmetric, single-axis trigonal system, the space group is P31m, a is 8.6899(6) Å, c is 5.0028(6) Å (beyond t. et al, crystal structure of potassium pentadata, Acta chemical Scandinavia 48(1994)533-536) has basic structure conditions for generating SHG effect, the characteristics of the crystal structure are further analyzed, and V₅O₁₄ ^-3The coplanarity and strong polarity of anionic groups, and the V-O bonds of all the trigonal and tetragonal vertexes are oriented in the same direction parallel to the c axis, so that the structural characteristic is favorable for generating strong NLO effect, and the crystal has large birefringence (n)_o＝2.42，n_e1.748), which shows that the crystal is easier to satisfy the phase matching of NLO.

According to the analysis and research of the relationship between the molecular composition, the crystal structure and the NLO performance, we provide a method for synthesizing a crystal with NLO performanceNovel NLO crystal material potassium pentavanadate (K)₃V₅O₁₄). Although already having K₃V₅O₁₄The research report of the crystal structure is reported, but the research and the application report related to the NLO crystal material, the spectral performance, the crystal growth and the like are not reported.

The invention aims to disclose a novel NLO crystal material potassium pentavanadate K of middle and far infrared wave bands₃V₅O₁₄. The technical scheme for realizing the invention is as follows:

with analytically pure K₂CO₃And V₂O₅(99.9%) as raw material, the molar ratio is 1: 1-1: 1.5, the raw material is put into a platinum crucible after being ground and mixed, the temperature is heated to 750-760 ℃, the heating rate is 2-4 ℃/min, the temperature is kept for 1-2 hours, then the crucible is naturally cooled to 200 ℃, the Pt crucible is taken out and put into a dryer, the Pt crucible is taken out after being cooled to room temperature, dark red K is observed on the surface of the crucible₃V₅O₁₄A crystal having the chemical reaction formula:

the crystal is insoluble in water and slightly soluble in acid.

The synthesized K was determined using a Delta Series TGA7 thermal analyzer₃V₅O₁₄Differential thermal curve of the crystalline powder, showing K₃V₅O₁₄The melting point of the melting peak of the crystal is about 400-410 ℃, which shows that the system has the melting temperature of the same components.

K₃V₅O₁₄The spectrum of the crystal is measured by visible and infrared spectrometers, and the transmission spectrum shows K₃V₅O₁₄The transmission spectrum of the crystal can be deep into the middle and far infrared region, and the transmission range is 0.4-11 μm. And LiNbO₃And β_II-LiVO₄Has a transmission range of 0.4 to 5 μm.

K measurement with YAG Q-switched laser (1.064 μm)₃V₅O₁₄The strong green frequency doubling effect is observed, and the SHG effect and LiNbO effect are combined₃And (4) the equivalent.

K₃V₅O₁₄The molecular weight of (1) is 596.06, the crystal structure belongs to a trigonal system, the crystal structure is a positive single optical axis, the space group is P31m, the unit cell parameter a is 8.6899(6) Å, c is 5.0028(6) Å, z is 1, and D is_c＝3.025gcm^-3As shown in fig. 1. It is structurally characterized in that₅O₁₄ ^-3The anion group is in a plane layered structure with strong polarity, the V-O bond length is strong in anisotropy and orientation consistency, so that K is ensured₃V₅O₁₄The crystal produces a strong NLO effect. The synthesized sample is measured by an X-ray powder diffraction method, and the intensity of the characteristic peak of the X-ray main diffraction and the value of the interplanar spacing d indicate that the synthesized and grown crystal is K with the space group P31m₃V₅O₁₄A crystal structure.

Compared with the background technology, the invention has the beneficial effects that: k₃V₅O₁₄The crystal has large NLO effect and intensity similar to LiNbO₃And β_II-LiVO₄The same spectrum range can be extended to middle and far infrared (0.4-11 μm) than LiNbO₃And β_II-LiVO₄The transmission range of the crystal is red-shifted by nearly 6 μm, so that K₃V₅O₁₄Can be used as NLO crystal material for middle and far infrared, such as CO₂Laser, frequency doubling the 1.06 μm fundamental wave of far infrared to the laser of middle and far infrared 0.53 μm (see FIG. 2)

Description of the drawings FIG. 1 is K₃V₅O₁₄A crystal structure of wherein

Represents K, ○ represents V,represents O; FIG. 2 is NLO K₃V₅O₁₄The crystal is used for frequency conversion of 1.06 μm wavelength laser, wherein 1 is total reflection mirror, 2 is Q-switched crystal, 3 is polaroid, 4 is YAG rod, 5 is output coupling mirror, 6 is collimating mirror, 7 is K₃V₅O₁₄Crystal, 8 is an attenuation sheet, 9 is a laser having a wavelength of 1.06 μm, 10 isThrough K₃V₅O₁₄The crystal frequency-doubled converts the generated 0.53 mu m laser.

Referring to fig. 2, first, He-Ne laser is used as a light source, each element is adjusted to be all on the same axis, and front and rear cavity pieces of a laser resonant cavity are adjusted to be parallel; then putting the Q-switched crystal 2 in a light path, switching on a power supply, finely adjusting the end of the holophote, forming a laser resonant cavity by the holophote 1, the Q-switched crystal 2, a polaroid 3, a YAG rod 4 and an output coupling mirror 5 to be a laser oscillator, and outputting the generated laser through a collimating mirror 6 to obtain an infrared laser 9 with an divergence angle smaller than 1 milliradian and a wavelength of 1.06 mu m; then K is put₃V₅O₁₄The crystal 7 is placed in a frequency doubling crystal frame, green light 10 with the wavelength of 0.53 mu m can be output to the attenuation sheet 8, and strong green light frequency doubling effect, SHG effect and LiNbO effect are observed₃And (4) the equivalent.

Claims

1. A non-linear optical crystal material potassium pentavanadate is characterized in that the molecular formula of the crystal is K₃V₅O₁₄Molecular weight 596.06, belonging to trigonal system, space group P31m, a 8.6899(6) Å, c 5.0028(6) Å, z 1, D_c＝3.025gcm^-3The crystal is dark red in color, and is poorly soluble in water and slightly soluble in acid.

2. A method for growing potassium pentavanadate crystals according to claim 1, wherein analytically pure K is used₂CO₃And V₂O₅(99.9%) as raw materials, the molar ratio is 1: 1-1: 1.5, the raw materials are ground, mixed and then placed in a platinum crucible, the temperature is raised to 750-760 ℃, the temperature raising rate is 2-4 ℃/min, the temperature is kept for 1-2 hours, then the mixture is naturally cooled to 200 ℃, the Pt crucible is taken out and placed in a dryer, the Pt crucible is taken out after being cooled to the room temperature, and then the K can be obtained₃V₅O₁₄And (4) crystals.

3. Use of a potassium pentavanadate crystal according to claim 1, wherein the crystal is used for a non-linear optical device in the mid-and far-infrared region.