The crystal laser of diode pumping as miniaturization, high-level efficiency, low threshold value solid light source, has obtained developing rapidly in recent years abroad.The dominant crystal in this field is Nd so far: YAG; But its status just is being subjected to vanadate single crystal, for example Nd-doped yttrium vanadate (Nd: YVO
4) challenge.As a kind of solid laser material, Nd: YVO
4Has very long and very interesting history.Breadboard J.O ' the Connor of Lincoln at first studied it as working-laser material in 1966, but growth cost costliness makes it impracticable.At the beginning of the seventies, Deshazer and other people find a kind of better method of the vanadate crystal of growing, so interest has been taken place the vanadic acid yttrium again.YVO
4Critical defect be that thermal conductivity is low, particularly under the high-average power flash lamp pumping, more be a problem.Along with the laser diode-pumped appearance and the improvement of crystal technique, Nd: YVO
4Just sell well again, and become the active material of low power laser, Nd: YVO
4Stimulated emission cross section be 4.6 times of Nd: YAG, threshold ratio Nd: YAG hangs down 50% (for 1.06 μ m); Nd: YVO
4>uptake factor of the broad absorption band of 20nm is about Nd: 8 times of YAG, and absorb temperature variation not too sensitive and insensitive to the diode wavelength; In addition, Nd: YVO
4Uniaxial crystal can get linearly polarized laser.This crystal is become be more suitable in the most effective solid laser material of diode pumping application.
Vanadic acid yttrium Nd: YVO
4It is the important laser crystals that middle nineteen sixties and Nd: YAG occurs simultaneously.Initial use molten-salt growth, but (be situated between surely distinguish very narrow etc.) can not get the crystal of Single-handed Dinghy open-Laser because the problem in the growth.Afterwards, gone out the crystal of certain size, but be subjected to YVO with Czochralski grown
4The influence of physico-chemical property contains iridium wrap and component and departs from the defective that causes in the crystal, make its in-fighting very big (be about high-quality Nd: YAG 10 times), thereby can't bring into play its good laser characteristics.Cause the reason of this defective: YVO
4Though be congruent fused compound, its fusing point height (~1840 ℃) needs to use high-melting-point crucible (as the iridium crucible) and non-oxide protective atmosphere.Under this condition, V
2O
5A large amount of volatilizations make melt depart from correct proportioning; The high price vanadium becomes vanadium at a low price simultaneously, and the oxygen that decomposites makes the iridium crucible oxidation, and therefore grow in the crystal little iridium sheet and bubble are difficult to obtain the high optical quality crystal.In addition, the crystal growth temperature in this method reaches 1940 ℃~1840 ℃, because the temperature height, thermal stresses is big, and usually causing in the middle of the crystal that is generated has a large amount of subgrain boundaries, causes crystal mass to descend.As having introduced a kind of float-zone method growth vanadate single crystal technology of distortion among the clear 49-5840 of Japanese Patent (on February 9th, 1974) " vanadate single crystal manufacture method ", this method also is to use the high growth temperature at 1940 ℃, it is to have adopted a kind of refractory metal to form the hot-plate of floating region as the fusing test portion, hot-plate be fixed between two electrodes and therein the heart have two apertures, the charge bar of the monocrystalline of waiting to grow is placed on the metal heater plate with central part with holes contacts, seed crystal is positioned over hot-plate followingly also makes it contact with central part with holes, energising can be heated to charge bar and seed crystal more than the fusing point, in both sides up and down near hot-plate, between charge bar and seed crystal, form the melting zone of the suspension of a suitable size, two melting zones communicate by the aperture on the hot-plate up and down, if when growing single-crystal, allow seed crystal slowly descend while rotating, charge bar also moves down at the same rate simultaneously, just can make melting zone keep constant, like this along with moving down of seed crystal and charge bar just grows needed monocrystalline gradually on seed crystal.But grow vanadate, for example also must there be aforesaid various shortcoming in YVO4 monocrystalline temperature equally up to 1940 ℃ under so high temperature.
Czochralski grown Nd: YVO is disclosed at another piece Japanese kokai publication hei-5-238897
4The technology of monocrystalline, but all fail to overcome above-mentioned drawback.
The objective of the invention is to overcome the shortcoming and defect of above-mentioned prior art,, reduce intracrystalline thermal stresses and prevent V in order to reduce crystal growth temperature
2O
5A large amount of volatilizations to avoid departing from of melt proportioning, grow high-quality practical optics crystal, thereby provide alkali-metal salt of a kind of use or oxyhydroxide to make mineralizer, adopt the useless crystal of melt method for growing or directly adopt V
2O
5And R
2O
3(R=Y wherein, Yb, Gd ... etc. transition element rare earth element particularly) admixture (Nd of raw material and trace, Er, Tm ..., Cr, Ni, Ti is etc. the transition element oxide compound of rare earth element particularly) do solute, the hydrothermal growing method of the vanadate single crystal of grow doping in autoclave.The object of the present invention is achieved like this:
Major equipment comprises: autoclave 1, process furnace 2 and electronic system 3, non corrosive lining 4 at autoclave inner chamber wall liner one inert material, it is characterized in that: may further comprise the steps: 1) solute raw material 5 to be crystallized is placed the bottom of the tubular autoclave 1 of belt material, one the center and
Edge perforate, percentage of open area are the top that 5~20% inert material plate washer 6 is placed on raw material 5; 2) in the vitellarium 8 on baffle plate 6 tops, hang some and have the vanadate seed wafer 9 of certain orientation; 3) in autoclave 1, pack into degree of filling be 60%~85% with alkali-metal salt or oxyhydroxide A
xM
y
It is main hydrothermal mineralization agent solution 10; 4) the sealing lining of inert material being done covers 15 and covers on the mouth of lining 4, sealing plug 14 is pressed in again
Also firmly tighten sealing nut 13 on the sealing cover; 5) autoclave of good seal is put into a process furnace 2 be warming up to the temperature (vitellarium) be 300-400 ℃,
Following temperature (dissolve area) is 350-470 ℃, makes dissolve area 7 and vitellarium 8 that the temperature difference of 40-100 be arranged,
Can grow; 6) just can obtain a certain size adulterated vanadate single crystal through the 2-4 time-of-week;
Wherein, employed alkali-metal salt or oxyhydroxide A as mineralizer
xM
yConcentration be 0.5-2.5mol/L, A=K, Na, Rb, M=OH, CO
3, F, X, y are positive integer, and its value is decided by the valency between them.One, the main preparation work before the growth: 1, the solute raw material can be the fragment vanadate crystal of (1) melt method for growing; (2) adopt V
2O
5And R
2O
3(R
=Y, Yb, Gd ... etc. transition element) and micro-admixture (Nd, Er, Tm ..., Cr, Ni, etc.
Transition element is the oxide compound of rare earth element particularly) the polycrystalline piece material that sinters into of mixing, pressure bar.2, solvent is done the aqueous solution that mineralizer is prepared with alkali-metal salt or oxyhydroxide, and its mineralizer concentration is 0.5
The A of-2.5mol/L
xM
y, (A=Na, K, Rb ..., M=CO
3, OH, F ..., x, y
Can be positive integer, its value be decided by the valency of A and M) 3, seed crystal is the vanadate of certain orientation, for example YVO
4Wafer through grinding (also polishing sometimes), punching
Become, grinding is mechanical stress and the surface imperfection that causes when eliminating cutting.Two, process of growth:
So-called hydrothermal growth is exactly that the solution of the acid that utilizes High Temperature High Pressure, alkali, salt makes those insoluble or the substance dissolves of indissoluble and methods of crystallization (or recrystallize) growing single-crystal under atmospheric condition usually.
Process of growth is as follows: with vanadate solute raw material to be crystallized, as Nd: YVO
4(5) place the band inert material, as platinum (or Au, Ag) bottom of Chen tubular autoclave (1); Inert material in the center and peripheral perforate, as Pt, Au, Ag etc. do the top that plate washer (6) is placed on raw material (5), dissolve area (7) and vitellarium (8) are separated, its baffle plate percentage of open area is 5~20%, and has flat board or umbrella configuration, and it not only helps the transmission of solute but also help being divided into any configuration of two flat-temperature zones up and down; Pass the YVO of polishing with platinum filament
4The wafer hole hangs over seed crystal (9) vitellarium (8) on baffle plate top, seed orientation can be, for example: (100), (001), (011) and (110) etc., by desired solvent degree of filling (60%~85%) hydrothermal mineralization agent-alkali metal compound A that in autoclave (1), packs into
xM
y(A=Na wherein, K, Rb ..., M=CO
3, OH, F X, y is a positive integer, its value is decided by the valency of A and M) the aqueous solution (in fact being exactly solvent), concentration is 0.5-2.5mol/L, the sealing lining lid (15) that with a thickness is inert materials such as the bowl-type platinum making of 0.2mm then covers on the mouth of the lining (4) that inert materials such as platinum are made, its side tapering should be identical with the tapering of sealing plug downside, be that 59 ° steel sealing plug (14) is pressed on the sealing cover and firmly tightens sealing nut (13) again with a tapering, with put into behind the autoclave good seal process furnace (2) be warming up to the temperature (vitellarium) be 300-400 ℃, following temperature (dissolve area) is 350-470 ℃, (temperature rise rate be 60~120 ℃/h), make dissolve area (7) and vitellarium (8) that a suitable temperature difference be arranged, can grow.Through appropriate time, be generally (2-4 week) just can obtain a certain size adulterated vanadate single crystal.
Used major equipment comprises: the heat-resistance high-strength degree steel or the autoclave (1) of superalloy system, an electronic system (3) of using with the two-part resistance heading furnace (2) and the controlled temperature of Kang Taisi (Kanthal super) coiling.Quartzy and except that growth, all need add the non corrosive lining (4) of one deck inert material (reaching high-temperature resistance plastice) at autoclave thorax inwall as platinum, gold and silver etc., its operation steps and flow process are as shown in Figure 2.The invention has the advantages that:
Hydrothermal growth is to carry out in an airtight belt material high pressure vessel, because the pressure of system is up to (hundreds of-several kilo-atmospheric pressures), temperature is again than crystal pulling method, flux method much lower (being approximately 300-450 ℃), the volatilization that prevents the system composition is is effectively scattered and disappeared, be easy to control growing crystalline component and prevent that system from being polluted, this be general flux method and crystal pulling method can't accomplish.Simultaneously because its growth temperature is low, and growth carries out with thermostatic process, and it is more much smaller than the viscosity of melt, therefore, high a lot of with the comparable additive method of the perfection of crystal of Hydrothermal Growth to add viscosity in aqueous solution.And exist subgrain boundary, wrap, scattering particles in the crystal of Czochralski grown always and cause defectives such as rimose thermal stresses, seriously affect the crystalline yield rate.In addition, hydrothermal method is easy to hang kind of a growth, and its output is proportional with the seed crystal number of being hung, as crystal growth.Such productive rate is more suitable for undoubtedly in suitability for industrialized production.Below in conjunction with drawings and Examples the present invention is described in detail:
The yttrium vanadate single crystal of embodiment 1 usefulness Hydrothermal Preparation neodymium-doped
With solute raw material to be crystallized, Nd: YVO
4(5) place the bottom of tubular autoclave (1) of the band platinum lining of φ 30mm, these raw materials are the Nd by Czochralski grown: YVO
4Useless crystal fracture becomes the fragment of 3~8mm and obtains.One its percentage of open area is 7% platinum system baffle plate (6) in the center and peripheral perforate, and it is placed on the top of raw material (5) so that dissolve area (7) and vitellarium (8) are separated.Hang the YVO that four X-cut with Z-and cut the section of a axle and c axle (promptly perpendicular to) in the vitellarium (8) on baffle plate (6) top
4Seed wafer (9), initial seed wafer (9) also are that the crystal by Czochralski grown cuts; Degree of filling by 70% concentration of packing in autoclave (1) is the commercially available K of 1.5mol/L
2CO
3Solution, then with autoclave sealing and put into a tubular electric resistance process furnace (2) and heat up, the vitellarium is 370 ℃, dissolve area is 420 ℃, makes dissolve area (7) and vitellarium (8) that 50 ℃ the temperature difference be arranged; Through two weeks just obtaining the transparent Nd that does not split: YVO
4Monocrystalline, the monolateral growth rate of its c and a direction are respectively 0.21 and 0.15mm/d.The yttrium vanadate single crystal of embodiment 2 usefulness polycrystal raw material hydrothermal growth neodymium-dopeds
Take by weighing the V of 300 grams by 1: 1 mole stoichiometric
2O
5And Y
2O
3And in the ratio of 3at% concentration (is benchmark with the Y atom) Nd with respective amount
2O
3Mix wherein, be pressed into the pole that diameter is 6~8mm behind the mixing, again the charge bar that presses is put into the Si-Mo rod stove afterwards and can obtain Nd: YVO in 14 hours at 1400 ℃ of sintering
4The polycrystalline ceramics raw material.With the Nd that sinters: YVO
4The polycrystalline charge bar cuts into 3~12mm segment and can directly place the bottom of the band platinum lining shape autoclave (1) of φ 30mm to make raw material as raw material (5); One in the center and peripheral perforate, and its percentage of open area is the top that the baffle plate (6) of 9% platinum system φ 28mm is placed on raw material (5), and dissolve area (7) and vitellarium (8) are separated; In the vitellarium (8) on baffle plate top, hang four YVO
4(100) seed wafer (9), initial seed wafer also is that the crystal with Czochralski grown cuts perpendicular to a axle.Degree of filling by 75% concentration of packing in autoclave (1) is the commercially available K of 1.0mol/L
2CO
3Solution, the tubular electric resistance process furnace (2) that then autoclave is sealed and puts into a usefulness Kang Taisi (Kanthal super) coiling heats up, and last temperature is 375 ℃, and following temperature is 435 ℃, makes that the dissolve area (7) and the temperature difference of vitellarium (8) they are 60 ℃.Just can obtain the transparent Nd that does not split: YVO through 14 days growth cycles
4Monocrystalline, the monolateral growth rate of its a direction is 0.12mm/d.It is worthy of note that the integrity of growing crystal is also directly relevant with the quality of seed crystal.The hydrothermal growth of the yttrium vanadate single crystal of embodiment 3 er-dopeds
Take by weighing the 300 gram pure V in commercial reagent by 1: 1 mole stoichiometric
2O
5And Y
2O
3And in the ratio of 2at% erbium concentration (is benchmark with the Y atom) Er with respective amount
2O
3Mix in the weighing, be pressed into the pole that diameter is 6~8mm behind the mixing, again the charge bar that presses is put into the Si-Mo rod stove afterwards, can obtain Er: YVO in 14 hours at 1400 ℃ of sintering
4The polycrystalline ceramics raw material.With the Er that sinters: YVO
4The polycrystalline charge bar cuts into 3~12mm segment and can directly place the bottom of the band platinum lining shape autoclave (1) of φ 30mm to make raw material as raw material (5); One in the center and peripheral perforate, and its percentage of open area is that the top that the baffle plate (6) of 7% platinum system φ 28mm is placed on raw material (5) separates dissolve area (7) and vitellarium (8); In the vitellarium (8) on baffle plate top, hang two YVO
4(100) seed wafer (9), initial seed wafer also cuts the section of (100) face with Czochralski grown crystal.Degree of filling by 75% concentration of packing in autoclave (1) is the commercially available Na of 1.2mol/L
2CO
3Deionized water solution, then with autoclave sealing and put into tubular electric resistance process furnace (2) intensification of a usefulness Kang Taisi (Kanthal super) coiling, last temperature is 370 ℃, following temperature is 435 ℃, making the temperature difference of dissolve area (7) and vitellarium (8) is 65 ℃.Just can obtain the transparent Er that does not split: YVO through 12 days growth cycles
4Monocrystalline, the monolateral growth rate of its a direction is 0.13mm/d.The hydrothermal growth of the vanadic acid gadolinium monocrystalline of embodiment 4 neodymium-dopeds
GdVO with melt method for growing
4Fragment is made solute, also can be directly takes by weighing the Gd that gross weight is 250 grams by 1: 1 Mol ratio
2O
3And V
2O
5And in the ratio of the neodymium concentration (is benchmark with the Y atom) of 3at% Nd with respective amount
2O
3Mix wherein, be pressed into the pole that diameter is 6~8mm behind the mixing, again the charge bar that presses is put into the Si-Mo rod stove afterwards, can obtain the GdVO of neodymium-doped at 1400 ℃ of sintering in 14 hours
4The polycrystalline charge bar.Again seed crystal is also changed into GdVO from melt method for growing
4The corresponding wafer that crystal cuts is the equipment of available accompanying drawing 1, adopts the technological process of embodiment 1 or 2 to grow the vanadic acid gadolinium monocrystalline of neodymium-doped.
Be noted that the above embodiments just illustrate the present invention with some concrete examples, it should not be a limitation of the present invention.Simultaneously, be familiar with all knowing of this technology, can carry out not departing from less than the various improvement of describing in the text the spirit and scope of this patent to the present invention.