CN101775651A

CN101775651A - Single crystal growth method of monopotassium phosphate with large caliber and high quality

Info

Publication number: CN101775651A
Application number: CN200810071779A
Authority: CN
Inventors: 李国辉; 李征东; 苏根博; 贺友平; 林秀钦; 庄欣欣
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: 2009-01-09
Filing date: 2009-01-09
Publication date: 2010-07-14
Anticipated expiration: 2029-01-09
Also published as: CN101775651B

Abstract

The invention relates to a single crystal growth method of monopotassium phosphate with large caliber and high quality, comprising the following steps: when seed crystal forms a cone, initial growth temperature lowers to the temperature of 0.5 DEG C below solution saturating point, and cone forming begins; cooling rate is controlled at 0.05 DEG/ day; the mode of cooling by stage is adopted after the seed crystal is in phragmocone; the crystal is in phragmocone until 50 DEG C; cooling rate is kept to 0.05 DEG C/ day; at the temperature of 50-35 DEG C, cooling rate is kept to 0.1 DEG C/ day; at the temperature of 35 DEG C to room temperature, cooling rate is kept to 0.15 DEG C/ day; a crystal rotation mode adopts the following circulation sequence: quickening, positive rotating, slowing down, stalling, quickening, reverse rotating, slowing down and stalling; seed crystal rotates at time interval as follows: 20 seconds, 60 seconds, 20 seconds, 20 seconds, 20 seconds, 60 seconds, 20 seconds and 20 seconds; and the positive rotating rate and the reversal rate are kept to 40-60 turns/ minute.

Description

A kind of single crystal growth method of monopotassium phosphate with large caliber and high quality

Technical field

The present invention relates to crystal growth, especially relate to heavy caliber (＞350mm) high quality potassium primary phosphate (KH ₂PO ₄, be called for short KDP) and the cooling growth of single crystal.

Background technology

The KDP crystal is a kind of good nonlinear optical material, be mainly used in two, three, four frequencys multiplication of laser, especially fine large size KDP crystal has been classified as unique Applied Materials of laser fusion frequency inverted at present in the world, also is the hot subject of current international Study on Crystals Growth.So far domestic still prolonging with traditional cool-down method carries out the heavy caliber single crystal growing.

Heavy caliber KDP crystal falling temperature method growth is at φ a 1200 * 1600mm, and volume is to carry out in 1.5 tons the cylindrical stainless steel crystal growth cylinder.Growth apparatus as shown in Figure 1, wherein 1 for crystal growth cylinder 2 be cylinder cap 3 for carrier crystal stand open holes 4 be engineering plastics overcoat for the agitator 11 of cleansing bath tub for the well heater 12 of cleansing bath tub for cleansing bath tub viewing window 10 for thermostat(t)ed water bathtub 9 for lighting window 8 for view port 7 for the leg 6 of cylinder body for handle hole 5.Cylinder cap 3 is made up of lid flange 2-1, flange seal circle 2-2; The tabular seed crystal 14 of heavy caliber KDP is put upside down and is fixed on 16 li one-tenth awl 15 growths of saturated KDP growth solution of putting into crystal growth cylinder 1 on the carrier crystal stand 13 during growth.For the heavy caliber that guarantees to grow (＞350mm) KDP crystal, saturated solution has enough salt amounts of folding, the temperature of saturation of general saturated solution is 60-70 ℃.

Its process control condition of traditional heavy caliber KDP crystal growth in the past is that seed crystal one-tenth awl maintenance rate of temperature fall is 0.2 ℃/day, keeping rate of temperature fall after becoming awl to finish is 0.1 ℃/day, according to " quicken-just changeing-slow down-stall-acceleration-counter-rotating-deceleration-stall " circular order, the timed interval is that the pattern of " 10 seconds-60 seconds-10 seconds-15 seconds-10 seconds-60 seconds-10 seconds-15 seconds " is rotated seed crystal, and keeping rotating speed is 90-120 rev/min.Under such control condition, it is 0.2 ℃/day that seed crystal becomes awl to keep rate of temperature fall, the cooling amount causes the accumulation of degree of supersaturation to increase too greatly easily, be easy to occur " drawing awl " phenomenon, as shown in Figure 2, the time that seed crystal becomes to bore prolongs the KDP crystalline production cycle greatly, and lineae ablicantes appears in crystalline each crystal face easily, influences final product quality.In very long crystal transparent layer process of growth, producing moisture evaporation inevitably runs off, should control low rate of temperature fall, rate of temperature fall is 0.1 ℃ of/day accumulation that also can cause the solution degree of supersaturation, destroys the growth of the crystal conical surface, and along with downward growth, crystal growth face increases, can not adopt fixed cooling pattern, cause the crystal pointization, as shown in Figure 3.In crystal transparent layer process of growth, each cylinder is different with the conical surface speed of growth, as shown in Figure 4, crystalline weight center line and crystalline rotating middle shaft line do not overlap, acceleration in the Crystal Rotation pattern, deceleration and run-down time are every too weak point and rotating speed are too fast, the inner shearing force that produces of crystalline, cracking easily.

Summary of the invention

The present invention adopts a kind of process control method of new large caliber and high quality KDP crystal growth, when tabular seed crystal begins into awl, add 0.5 ℃ of degree of supersaturation, be that the initial growth temperature drops to the solution saturation point and begins into awl for following 0.5 ℃, can prevent effectively that so tabular seed crystal from becoming the bipyramid phenomenon, as shown in Figure 5, prolonged the seed crystal phragmocone time.Seed crystal becomes in the awl process, and the control rate of temperature fall is 0.05 ℃/day, prevents that lineae ablicantes from appearring in the accumulation increase of degree of supersaturation and crystal outside surface transparent layer.After the seed crystal phragmocone, crystal enters the transparent layer growth, because crystal transparent layer growth time is longer, at volume is that 1.5 tons cylindrical stainless steel crystal growth cylinder growth produces moisture evaporation inevitably and runs off, should control low rate of temperature fall, prevent the accumulation of solution degree of supersaturation, destroy the growth of the crystal conical surface.Crystal is grown downwards simultaneously, and crystal growth face increases, and can not adopt fixed cooling pattern, causes the crystal pointization.At above-mentioned situation, in crystal transparent layer process of growth, adopt the pattern of lowering the temperature stage by stage, crystal phragmocone to 50 ℃ keeps 0.05 ℃/day of rate of temperature fall; 50 ℃ to 35 ℃, keep 0.1 ℃/day of rate of temperature fall, 35 ℃ to room temperature, keeps 0.15 ℃/day of rate of temperature fall.The Crystal Rotation pattern is according to " quicken-just changeing-slow down-stall-acceleration-counter-rotating-deceleration-stall " circular order, the timed interval is that the pattern of " 20 seconds-60 seconds-20 seconds-20 seconds-20 seconds-60 seconds-20 seconds-20 seconds " is rotated seed crystal, keeping rotating speed is 40-60 rev/min, prolong acceleration, deceleration and run-down time to 20 second, reduce rotating speed, Crystal Rotation is more steady.

Adopt the process control method of new crystal growth, the KDP crystal that grows as shown in Figure 6, it is 45 ° that crystal becomes coning angle, the awl phenomenon does not appear drawing, crystal becomes the awl back cylinder and the conical surface not to occur lineae ablicantes fully and add crystalline substance, and four conical surface speeds of growth are suitable, big facet do not occur, improve the KDP crystal mass effectively, increase the crystal growth success ratio.The downward speed of growth of crystal shortens the crystal growth cycle than fast under the processing condition in the past.

Description of drawings

Fig. 1 is the cylindrical stainless steel crystal growth of φ a 1200 * 1600mm cylinder.

Fig. 2 is the KDP crystal phenomenon of " drawing awl "

Fig. 3 is a KDP crystal growth pointization phenomenon.

Fig. 4 forms big or small conical surface phenomenon in the KDP crystal growth.

Fig. 5 becomes " bipyramid " phenomenon for the KDP crystal.

The KDP crystal that Fig. 6 grows for the process control method that adopts new crystal growth.

Embodiment

In being of a size of φ 1200 * 1600mm crystal growth cylinder (2), the KDP powder of the AR level that Shanghai reagent two factories of adding 750Kg produce, add 1.5 tons of ultrapure waters that form through the rich ultrapure filtration system filters of overstocked reason again, its specific conductivity reaches 18.2M Ω cm, after being mixed with saturation point and being 61.0 ℃ saturated KDP growth solution, be warming up to 75 ℃, overheated constant temperature 24 hours.A tabular KDP seed crystal that is of a size of 360 * 360 * 20mm is tipped upside down on the carrier crystal stand, after 24 hours, introduce in the KDP saturated solution and cool the temperature to 60.5 ℃, set 0.05 ℃/day of rate of temperature fall, become to bore growth in baking under 75 ℃.The Crystal Rotation pattern is according to " quicken-just changeing-slow down-stall-acceleration-counter-rotating-deceleration-stall " circular order, the timed interval is that the pattern of " 20 seconds-60 seconds-20 seconds-20 seconds-20 seconds-60 seconds-20 seconds-20 seconds " is rotated seed crystal, and keeping rotating speed is 40-60 rev/min.Crystal perfection phragmocone after 60 days, growth temperature are 57.5 ℃, adopt the pattern of lowering the temperature stage by stage, 57.5 ℃ to 50 ℃, keep 0.05 ℃/day of rate of temperature fall; 50 ℃ to 35 ℃, keep 0.1 ℃/day of rate of temperature fall, 35 ℃ to room temperature, keeps 0.15 ℃/day of rate of temperature fall, and crystal enters the transparent layer growth, as shown in Figure 6, speed of growth 2mm/ days downwards.

Claims

1. a single crystal growth method of monopotassium phosphate with large caliber and high quality comprises the steps:

(1) when seed crystal became awl, the initial growth temperature dropped to the solution saturation point and begins into awl for following 0.5 ℃, the control rate of temperature fall be 0.05 ℃/day to the seed crystal phragmocone;

(2) after the seed crystal phragmocone, adopt the pattern of lowering the temperature stage by stage, crystal phragmocone to 50 ℃ keeps 0.05 ℃/day of rate of temperature fall; 50 ℃ to 35 ℃, keep 0.1 ℃/day of rate of temperature fall, 35 ℃ to room temperature, keeps 0.15 ℃/day of rate of temperature fall;

(3) the Crystal Rotation pattern is according to " quicken-just changeing-slow down-stall-acceleration-counter-rotating-deceleration-stall " circular order, the timed interval is that the pattern of " 20 seconds-60 seconds-20 seconds-20 seconds-20 seconds-60 seconds-20 seconds-20 seconds " is rotated seed crystal, and rotating speed is 40-60 rev/min.