CN100587131C - Process for preparing lead tungstate-doped crystal - Google Patents

Abstract

The invention discloses a preparing method of doped lead tungstate crystal, which comprises the following steps: (1) drying PbO, WO3 with purity at 99.99% and solid powder of doping agent under 150-200 Deg C; weighing the PbO and WO3 according to chemical weight; setting the molar rate density of doping agent at 0.01-0.1%; pressing weighted solid powder into dense solid under 10-50Kpa; sintering in the oxidizing environment at 750-1000Deg C; aerating oxygen in the sealed platinum copple; insulating at 1130-1200 Deg C to fuse the solid; (2) introducing fused raw material into growing copple with seed to form dense multi-crystal ingot; placing the growing copple in the temperature-gradient crystal growing furnace to inoculate and grow with introducing speed at 1.0mm/h. The invention is fit for effumable doping agent, which is also fit for doping agent without effumability.

Description

Preparing method of doped lead tungstate crystal

Technical field

The present invention relates to field of crystal growth, particularly a kind of preparation method of doped lead tungstate crystal.

Background technology

Prior art is more successful during than higher oxide doped and modified crystal of lead tungstate at growth plumbous tungstate and some fusing points, but when mixing, the hotchpotch of growth low-melting point high volatility meets difficulty, because in these devices during growing crystal, a part of space need be reserved usually so that the oxygen that the splendid attire crystal growth needs in crystal raw material top in the crucible, temperature distribution in the crystal growing furnace as shown in Figure 1, upper temp is higher, crystal growth raw material and doping agent are in melted state, and mixing does not have volatile dopant such as La ₂O ₃The time space reserved be not fairly obvious to the crystal growth influence, but lower at the growth fusing point, volatility is bigger as PbF ₂During Deng dopant, the serious volatilization of dopant can make doping may realize hardly.

In order to address this problem, Chinese application number 200310109408.4 " preparation method of fluorine-ion-doped plumbous tungstate scintillation crystal " discloses a kind of crystal of lead tungstate of growing after finishing that utilizes at airtight PbF ₂High temperature diffusion in the atmosphere, the thermodiffusion character of material makes PbWO when attempting to utilize high temperature ₃The growing technology of crystal doping modification, this growing technology can make crystal of lead tungstate obtain a part of PbF ₂Mix, but thermodiffusion is very difficult in the solid, diffusion is along with the increase of the degree of depth significantly descends PbF ₂Concentration in crystal is low and to distribute be uneven.So this PbF ₂: PbWO ₄There are two difficulties that are difficult to overcome in crystal technique: the first can't guarantee that doped crystal obtains needed doping content; It two is PbF in the crystal ₂The doping content skewness, therefore this method is difficult to grow fine PbF ₂: PbWO ₄Crystal.

Summary of the invention

Technical problem to be solved by this invention provides and a kind ofly can guarantee doping content, and the preparation method of doped lead tungstate crystal of uniform doping, the technical scheme that it adopts is: a kind of preparation method of doped lead tungstate crystal is characterized in that comprising the steps:

(1) with purity is 99.99% PbO, WO ₃With the doping agent solid state powder after 150 ℃ of-200 ℃ of dryings, PbO and WO ₃According to the stoichiometric ratio weighing, the volumetric molar concentration of doping agent is 0.01%-0.1%, load weighted pressed powder is pressed into the compact mass solid under 10Kpa-50Kpa pressure, sintering in 750 ℃ of-1000 ℃ of oxidizing atmospheres, 1130 ℃ of-1200 ℃ of constant temperature make it to melt fully half an hour in the airtight platinum crucible that charges into oxygen;

(2) raw material after will melting is incorporated in the growth crucible that is equipped with seed crystal, forms the dense multicrystalline ingot, and this growth crucible is placed inoculation in the tgt crystal growth stove, growth, obtains finished product; Speed is 1.0mm/h under the drawing of crucible in growth furnace.

Wherein, the temperature distribution history in the crystal growing furnace divides four sections, is followed successively by from top to bottom:

The 1st section temperature is 500 ℃～1123 ℃ scopes, and the raw material that is in this temperature province does not melt;

The 2nd section temperature is 1123 ℃～1400 ℃ scopes, and raw material here is melted, and the 1st section and the 2nd section intersection are growth raw material fusing point place;

The 3rd section temperature is at 1123～700 ℃, and temperature is lower than the growth raw material fusing point, and the crystal here is in crystallization, and the 2nd section and the 3rd section intersection are crystal growth point temperature, and the 2nd section humidity province thermograde is big, and the motivating force of crystal structure is provided;

Nethermost the 4th section humidity province, temperature range be 700 ℃ with down to room temperature, this zone is the good crystal of having grown.

The invention has the beneficial effects as follows:

In crystal growing process; part material fusing in the growth crucible; the part that being in crucible top does not have to melt is a blocks of solid; the volatilization of volatile gases in the melt below can suppressing or block; form solid envelope, and protection growth melt is unlikely to its bath composition because the serious volatilization of a certain component makes melt composition depart from the proportioning of crystal growth requirement.Therefore it is not only applicable to the volatile doping agent that mixes, and being applicable to too simultaneously mixes does not have volatile doping agent.

Description of drawings

Fig. 1 is a temperature distributing curve diagram in the prior art crystal growing furnace burner hearth;

Fig. 2 is a temperature distributing curve diagram in the crystal growing furnace burner hearth of the present invention.

Embodiment

Below in conjunction with accompanying drawing, be PbF with the doping agent ₂, Yb ₂O ₃, BaF ₂The invention will be further described as embodiment.

Embodiment 1:

A kind of PbF ₂: PbWO ₄The crystal preparation method comprises the steps:

(1) with purity is 99.99% PbO, WO ₃With doping agent PbF ₂Solid state powder after drying about 150 ℃, PbO and WO ₃According to the stoichiometric ratio weighing, doping agent PbF ₂Volumetric molar concentration be 0.01%, load weighted pressed powder is pressed into the compact mass solid under 10Kpa pressure, sintering in 750 ℃ of oxidizing atmospheres, 1130 ℃ of constant temperature make it to melt fully half an hour in the airtight platinum crucible that charges into oxygen;

(2) raw material after will melting is incorporated in the growth crucible that is equipped with seed crystal, forms the dense multicrystalline ingot, and this growth crucible is placed inoculation in the tgt crystal growth stove, growth, obtains finished product PbF ₂: PbWO ₄Crystal; Wherein the temperature distribution history in the tgt crystal growth stove divides four sections as shown in Figure 2, and be followed successively by from top to bottom: the 1st section temperature is 500～1123 ℃ of scopes, and temperature is lower, and the raw material that is in this temperature province does not melt; The 2nd section temperature height, 1123～1400 ℃ of scopes, raw material here is melted, and the 1st section and the 2nd section intersection are growth raw material fusing point place; The 3rd section temperature is 1123～700 ℃ of scopes, temperature is lower than fusing point, the crystal here is in crystallization, the 2nd section and the 3rd section intersection are crystal growth point temperature, and the 2nd section humidity province thermograde is big, and the motivating force of crystal structure is provided, nethermost the 4th section humidity province, temperature range be 700 ℃ with down to nearly room temperature, this zone is the good crystal of having grown, wherein speed is 1.0mm/h under the drawing of crucible in growth furnace.

Embodiment 2:

A kind of Yb ₂O ₃: PbWO ₄The crystal preparation method comprises the steps:

(1) with purity is 99.99% PbO, WO ₃With doping agent Yb ₂O ₃Solid state powder after drying about 180 ℃, PbO and WO ₃According to the stoichiometric ratio weighing, doping agent Yb ₂O ₃Volumetric molar concentration be 0.05%, load weighted pressed powder is pressed into the compact mass solid under 30Kpa pressure, sintering in 900 ℃ of oxidizing atmospheres, 1160 ℃ of constant temperature make it to melt fully half an hour in the airtight platinum crucible that charges into oxygen;

(2) raw material after will melting is incorporated in the growth crucible that is equipped with seed crystal, forms the dense multicrystalline ingot, and this growth crucible is placed inoculation in the tgt crystal growth stove, growth, obtains finished product Yb ₂O ₃: PbWO ₄Crystal; Wherein the temperature distribution history in the tgt crystal growth stove divides four sections as shown in Figure 2, and be followed successively by from top to bottom: the 1st section temperature is 500～1123 ℃ of scopes, and temperature is lower, and the raw material that is in this temperature province does not melt; The 2nd section temperature height, 1123～1400 ℃ of scopes, raw material here is melted, and the 1st section and the 2nd section intersection are growth raw material fusing point place; The 3rd section temperature is 1123～700 ℃ of scopes, temperature is lower than fusing point, the crystal here is in crystallization, the 2nd section and the 3rd section intersection are crystal growth point temperature, and the 2nd section humidity province thermograde is big, and the motivating force of crystal structure is provided, nethermost the 4th section humidity province, temperature range be 700 ℃ with down to nearly room temperature, this zone is the good crystal of having grown, wherein speed is 1.0mm/h under the drawing of crucible in growth furnace.

Embodiment 3:

A kind of BaF ₂: PbWO ₄The crystal preparation method comprises the steps:

(1) with purity is 99.99% PbO, WO ₃With doping agent BaF ₂Solid state powder after drying about 200 ℃, PbO and WO ₃According to the stoichiometric ratio weighing, doping agent BaF ₂Volumetric molar concentration be 0.1%, load weighted pressed powder is pressed into the compact mass solid under 50Kpa pressure, sintering in 1000 ℃ of oxidizing atmospheres, 1200 ℃ of constant temperature make it to melt fully half an hour in the airtight platinum crucible that charges into oxygen.

(2) raw material after will melting is incorporated in the growth crucible that is equipped with seed crystal, forms the dense multicrystalline ingot, and this growth crucible is placed inoculation in the tgt crystal growth stove, growth, obtains finished product BaF ₂: PbWO ₄Crystal; Wherein the temperature distribution history in the tgt crystal growth stove divides four sections as shown in Figure 2, and be followed successively by from top to bottom: the 1st section temperature is 500～1123 ℃ of scopes, and temperature is lower, and the raw material that is in this temperature province does not melt; The 2nd section temperature height, 1123～1400 ℃ of scopes, raw material here is melted, and the 1st section and the 2nd section intersection are growth raw material fusing point place; The 3rd section temperature is 1123～700 ℃ of scopes, temperature is lower than fusing point, the crystal here is in crystallization, the 2nd section and the 3rd section intersection are crystal growth point temperature, and the 2nd section humidity province thermograde is big, and the motivating force of crystal structure is provided, nethermost the 4th section humidity province, temperature range be 700 ℃ with down to nearly room temperature, this zone is the good crystal of having grown, wherein speed is 1.0mm/h under the drawing of crucible in growth furnace.

Claims (2)

1. a preparation method of doped lead tungstate crystal is characterized in that, comprises the steps:

1) with purity is 99.99% PbO, WO ₃With the doping agent solid state powder 150 ℃～200 ℃ dryings, then, PbO and WO ₃According to the stoichiometric ratio weighing, the volumetric molar concentration of doping agent is 0.01%～0.1%, load weighted pressed powder is pressed into the compact mass solid under 10Kpa～50Kpa pressure, sintering in 750 ℃～1000 ℃ oxidizing atmospheres, 1130 ℃～1200 ℃ constant temperature make it to melt fully half an hour in the airtight platinum crucible that charges into oxygen;

2) raw material after will melting is incorporated in the growth crucible that is equipped with seed crystal, forms the dense multicrystalline ingot, and this growth crucible is placed inoculation in the tgt crystal growth stove, growth, obtains finished product; Wherein speed is 1.0mm/h under the drawing of crucible in growth furnace, and the temperature distribution history in the crystal growing furnace divides four sections, is followed successively by from top to bottom:

The 1st section temperature is 500 ℃～1123 ℃ scopes, and the raw material that is in this temperature province does not melt;

The 2nd section temperature is 1123 ℃～1400 ℃ scopes, and raw material here is melted, and the 1st section and the 2nd section intersection are growth raw material fusing point place;

The 3rd section temperature is at 1123～700 ℃, and temperature is lower than the growth raw material fusing point, and the crystal here is in crystallization, and the 2nd section and the 3rd section intersection are crystal growth point temperature, and the 2nd section humidity province thermograde is big, and the motivating force of crystal structure is provided;

Nethermost the 4th section humidity province, temperature range be 700 ℃ with down to room temperature, this zone is the good crystal of having grown.

2. as claims 1 described preparation method of doped lead tungstate crystal, it is characterized in that described doping agent is La ₂O ₃Or PbF ₂Or Yb ₂O ₃

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