Process for preparing lead tungstate-doped crystal

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

technical field [0001] The invention relates to the field of crystal growth, in particular to a method for preparing doped lead tungstate crystals. Background technique [0002] The existing technology is relatively successful in growing lead tungstate and some oxides with relatively high melting point doping modified lead tungstate crystals, but it encounters difficulties in growing dopant doping with low melting point and strong volatility, because in these When growing crystals in the device, it is usually necessary to reserve a part of the upper part of the crystal raw material in the crucible to accommodate the oxygen required for crystal growth. The temperature distribution in the crystal growth furnace is shown in Figure 1. The upper part has a higher temperature, and the crystal growth raw materials and dopants In the molten state, doped with non-volatile doping substances such as La 2 o 3 The effect of the reserved space on crystal growth is not very obvious, but ...

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Problems solved by technology

[0002] The existing technology is relatively successful in growing lead tungstate and some oxides with relatively high melting point doping modified lead tungstate crystals, but it encounters difficulties in growing dopant doping with low melting point and strong volatility, because in these When growing crystals in the device, it is usually necessary to reserve a part of the upper part of the crystal raw material in the crucible to accommodate the oxygen required for crystal growth. The temperature distribution in the crystal growth furnace is shown in Figure 1. The upper part has a higher temperature, and the crystal growth raw materials and dopants In the molten state, doped with non-volatile doping substances such as La 2 o 3 The effect of the reserved space on crystal growth is not very obvious, but in the growth of low melting point and high volatility such as PbF 2 When doping substances, the severe volatilization of doping substances will make doping almost impossible

[0003] In order to solve this problem, Chinese application number 200310109408.4 "Preparation method of fluoride ion-doped lead tungstate scintillation crystal" discloses a method of using the grown lead tungstate crystal in a closed PbF 2 High-temperature diffusion in the atmosphere, trying to use the thermal diffusion properties of substances at high temperatures to make PbWO 3 Crystal doping modification growth technology, this growth technology can make lead tungstate crystal obtain a part of PbF 2 Doping, but the thermal diffusion in the solid is very difficult, and the diffusion decreases significantly with the increase of the depth, PbF 2 The concentration in the crystal is low and the distribution is uneven

Therefore this PbF 2 :PbWO 4 There are two insurmountable difficulties in crystal growth technology: one is that the doped crystal cannot be guaranteed to obtain the required doping concentration; the other is that the PbF in the crystal 2 The distribution of doping concentration is not uniform, so it is difficult to grow high-quality PbF by this method 2 :PbWO 4 the crystal

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