CN101780959B - Preparation method of Bi4Si3O12 nanocrystals - Google Patents

Abstract

The invention relates to a preparation method of Bi4Si3O12 nanocrystals. The method comprises the following steps: mixing bismuth trioxide powder with quartz sand powder to obtain mixed powder; adding the mixed powder in a crucible which is placed in a muffle furnace for melting, then pouring the molten glass on a room-temperature stainless steel plate, cooling to obtain bismuthate glass; placing the prepared bismuthate glass on a high purity aluminum oxide plate, placing the plate in the muffle furnace to heat, cooling to obtain the Bi4Si3O12 nanocrystals. The invention adopts high-temperature charging, high-temperature rapid melting, high-temperature stirring and other processes to ensure the mixed powder to form uniform molten glass. In the method of the invention, nucleating agent is not added during the preparation of Bi4Si3O12 nanocrystals, the grain size of the prepared Bi4Si3O12 nanocrystals is small, the nanocrystals are shaped like needles or bars and have uniform size, high crystallinity, high crystal purity and less impure phases; and the raw materials have cheap price, rich sources, low synthesis temperature and simple preparation technology and are applicable to industrial production.

Description

A kind of Bi＜sub〉4＜/sub〉Si＜sub〉3＜/sub〉O＜sub〉12＜/sub〉preparation of nano crystal

Technical field

The present invention relates to a kind of preparation of nano crystal, particularly a kind of Bi ₄Si ₃O ₁₂Preparation of nano crystal.

Background technology

Discovered in recent years Bi ₂O ₃-SiO ₂System is the system that further researching value is arranged very much.Phases such as the compound crystalline phase of finding in this system has 6: 1,1: 1 and 2: 3 have been found out Bi ₁₂SiO ₂₀Crystal has performances such as electric light, photoconduction, light are sold off, piezoelectricity, acousto-optic, optically-active, Bi ₄Si ₃O ₁₂Crystal has performances such as electric light, flicker.But, except to Bi ₁₂SiO ₂₀Aspects such as near facies relationship forming and crystalline growth thereof, character, application have outside the more detailed research, the most of zone of this system lacks careful and research in depth basically, a reason is that other crystal is difficult to synthesize in this system's composition, and be easy to produce dephasign in the building-up process, this is bigger to prepared monocrystalline performance impact, therefore prepares the basis that highly purified crystal raw material is the high-quality transparent single crystal body of preparation.Seeking new functional crystal is international crystalline material FRONTIER IN SCIENCE, and the research of aspects such as the prediction of new functional crystal, feedstock production, crystallization behavior, crystal growth is the basis of new functional crystal research.

Bi ₄Si ₃O ₁₂Be a kind of novel scintillation crystal, become scintillator Bi with its favorable mechanical and chemical stability, good photoelectricity, thermoluminescence etc. ₄Ge ₃O ₁₂One of best substitute.Although people are familiar with Bi ₄Si ₃O ₁₂There is more than 170 year, but utilized Czochralski grown to go out its monocrystalline up to the talents such as Philips-born in 1971.In recent years, Shanghai Inst. of Silicate, Chinese Academy of Sciences utilizes falling crucible method also to grow monocrystalline (FanShiji, et al.The Eleventh Inter-national Conference on CrystalGrowth, Advance Program, 1995.30).Bi ₄Si ₃O ₁₂Crystal belongs to isometric system, I43d spacer, a=10.299

Z=4.Its structure can be regarded as by [SiO ₄] tetrahedron and [BiO ₆] octahedra formation.Bi ₄Si ₃O ₁₂Crystal all is transparent in visible light and near infrared range.

At present, Bi ₄Si ₃O ₁₂Synthetic method mainly be solid-phase synthesis and sol-gel method.IshiIM in 1997 etc. utilize Bridgman-Stockbarge method for growing to go out large-sized Bi ₄Si ₃O ₁₂Monocrystalline.The Fei Yiting of Shanghai Inst. of Silicate, Chinese Academy of Sciences in 2000 etc. also utilizes this method high-quality Bi that grown ₄Si ₃O ₁₂Monocrystalline.Zhang Zhengguang etc. have prepared with sintering process under normal pressure and have had the Bi that height has sequential structure ₄Si ₃O ₁₂Crystallite.And analyzed generation crystalline thing mutually and microscopic appearance.The result shows that prepared is the Bi of cube phase ₄Si ₃O ₁₂Crystal, Bi ₄Si ₃O ₁₂Crystal grain always distributes in pairs, and is arranged in rows, thereby forms high orderly brilliant array structure.But, generate middle mutually dephasign and be difficult to eliminate.People such as Bai Chaohui (Bai Chaohui, Ba Xuewei, Jia Ru, Chinese Journal of Inorganic Chemistry, 2006,22:1327～1329) utilize Prepared by Sol Gel Method Bi ₄Si ₃O ₁₂In the process of nano-powder, having obtained principal crystalline phase in the time of 550～650 ℃ is Bi ₂SiO ₅And Bi ₂O ₃The mixing crystalline phase, along with the rising of temperature of reaction, Bi ₂SiO ₅And Bi ₂O ₃Constantly reaction has generated the target product Bi of principal crystalline phase for cube crystalline phase in the time of 750 ℃ ₄Si ₃O ₁₂Bi such as Wang Yan ₂O ₃And SiO ₂Be raw material, according to amount of substance than n (Bi ₂O ₃): n (SiO ₂The sample of the about 60g of)=1: 1 preparation.Wet mixing 1.5h in the ethanol is poured in test earlier into, and it is even to guarantee sample to grind the dried 0.5h of mixing after the infrared oven dry again.750 ℃ of roasting 1h, Bi at this moment ₁₂SiO ₂₀And Bi ₂SiO ₅The diffraction peak of XRD stronger, soaking time lengthening, Bi ₂SiO ₅The diffraction peak of XRD weaken Bi ₁₂SiO ₂₀Diffraction peak further strengthen.In addition, give the differential thermal analysis curve of sample in the literary composition, as can be seen, sample is at 579.6 ℃ from differential thermal analysis curve, and 744.3 ℃, 829.3 ℃, 879.2 ℃ all have exothermic peak to occur.This component produces the crystalline kind in temperature-rise period more, prepares single crystal preparation technology and be difficult to control.Above agricolite crystalline is synthetic, and all to adopt silicon-dioxide be raw material, and synthetic method is very complicated, and if does not adopt high-temperature melting method all can not obtain pure agricolite crystal.

Patent CN200510046593.6 discloses and has a kind ofly contained the metal oxide of various active components such as molybdenum, iron, nickel, samarium and be the catalyzer that carrier is formed with silicon-dioxide, aluminum oxide or its mixture, can be used for third rare, isobutene ammonia oxidizing and prepares higher selection row third rare nitrile etc.CN10038071C provides a kind of preparation high purity silicic acid bismuth nano-powder, at first bismuth salt is dissolved in the organic solvent, forming the bismuth salt concn is the bismuth-containing solution of 0.5～5M, at Bi: Si=12 in molar ratio: 1 joins silicoorganic compound in the bismuth-containing solution, fully stir, form uniform solution, colloidal sol is adopted atmospheric evaporation or negative pressure evaporation, obtain exsiccant precursor powder, at last in the environment of aerobic, the precursor powder is carried out sintering, in lower temperature and short time, prepare the Bi of purity and better crystallinity degree ₄Si ₃O ₁₂Nanocrystalline.In addition, document (Journal ofMaterials Science Letters 1999,18:1871～1874) discloses a kind of method that adopts prepared by mechanical alloy agricolite nano-powder.This method is with Bi ₂O ₃And SiO ₂Powder (crystal) is a raw material, directly prepares Bi through high-energy ball milling ₄Si ₃O ₁₂Nanocrystalline, be characterized in utilizing the mechanical alloying reaction that two kinds of powders take place in collision and crushing process repeatedly to synthesize target product, thereby do not need extra high-temperature heat treatment, can obtain the agricolite nano-powder.Thereby can avoid the shortcoming of above-mentioned solid phase reaction sintering.But mechanical alloying method required time is longer, and production efficiency is lower, is not suitable as a kind of batch process Bi of practicality ₄Si ₃O ₁₂Nanocrystalline method.And, produce pollution owing in long high-energy ball milling process, can from grinding system (comprise grinding container and grind spheroid), introducing impurity inevitably, thereby be difficult to obtain highly purified Bi ₄Si ₃O ₁₂Nanocrystalline powder.This is for Bi ₄Si ₃O ₁₂Nanocrystalline application in photoelectron and photocatalysis field is very disadvantageous.And this complicated process of preparation.

In sum, Bi ₄Si ₃O ₁₂Crystal is a kind of superior performance, widely used material.Bibliographical information is mostly around Bi at present ₄Si ₃O ₁₂Crystalline preparation and applied research are about preparation Bi ₄Si ₃O ₁₂The raw materials used correlative study of crystal is not reported.

Summary of the invention

The objective of the invention is to overcome the shortcoming of above-mentioned prior art, provide a kind of preparation high quality, the Bi that can produce in batches ₄Si ₃O ₁₂Preparation of nano crystal.The Bi that makes according to preparation method of the present invention ₄Si ₃O ₁₂Nanocrystalline degree of crystallinity height, the purity height, dephasign is few, and cost of material is cheap, and the source is abundant, and preparation technology is simple, prepared Bi ₄Si ₃O ₁₂The nanocrystalline magnetron sputtering that can be used as prepares Bi ₄Si ₃O ₁₂The high purity target of film and preparation high quality Bi ₄Si ₃O ₁₂The raw material of macrocrystal.

For achieving the above object, the technical solution used in the present invention is:

The first step: the preparation of bismuthate glass

At first, with quartz sand and more than bismuthous oxide bismuth trioxide difference ball milling to 400 order, make powder raw material; Then according to mol ratio Bi ₂O ₃: SiO ₂=2: 3 after bismuthous oxide bismuth trioxide powder and quartz sand powder mixed mixed powder;

Secondly, 30% of mixed powder is added the crucible of putting into the globars electric furnace in advance, charge temperature is 1020 ℃ for the first time, be incubated and add remaining mixed powder again after 10～30 minutes, be warming up to 1150～1250 ℃ with 10～25 ℃/minute, close fire door, be incubated 1～2 hour, every 20 minutes crucible is taken out in the insulating process, adopt the high purity aluminium oxide rod that high-temperature fusant is stirred and put into stove immediately after 30 seconds; To found uniform glass metal after insulation finishes is that the fused mixed powder is poured on the stainless steel plate of room temperature, promptly obtains bismuthate glass after the cooling;

Second step: the Bi ₄Si ₃O ₁₂Nanocrystalline preparation

At first, prepared bismuthate glass is placed on the high purity aluminium oxide plate, and then alumina plate and bismuthate glass placed retort furnace together, be warming up to 900 ℃ of insulations 6～12 hours with 10 ℃/minute temperature rise rates from room temperature, be cooled to room temperature with 20 ℃/minute rate of temperature fall from 900 ℃ then, sample taken off from alumina plate promptly to get crystalline phase be Bi ₄Si ₃O ₁₂Nanocrystalline.

SiO of the present invention ₂Introduce by quartz sand, impurity iron content is less than 10ppm.

The present invention adds raw material by high temperature, and high temperature melts rapidly, and technologies such as high-temperature stirring are accelerated the glass metal that mixed powder forms congruent melting fast.The present invention is at preparation Bi ₄Si ₃O ₁₂Do not add nucleator when nanocrystalline, prepared Bi ₄Si ₃O ₁₂Nanocrystalline grain-size is little, is shaped as needle-like or bar-shaped, and size is even, the degree of crystallinity height, and the crystal purity height, dephasign is few, and cost of material is cheap, and the source is abundant, and synthesis temperature is lower, and preparation technology is simple, helps suitability for industrialized production.Prepared Bi ₄Si ₃O ₁₂The nanocrystalline magnetron sputtering that can be used as prepares Bi ₄Si ₃O ₁₂The high purity target of film and preparation high quality Bi ₄Si ₃O ₁₂The raw material of macrocrystal.

Description of drawings

Fig. 1 is the Bi that makes according to preparation method of the present invention ₄Si ₃O ₁₂The nanocrystalline diffraction photo that detects at X-ray diffractometer, wherein X-coordinate be diffraction angle 2 θ/(°), ordinate zou is a diffracted intensity.

Fig. 2 (a) and (b) are respectively the Bi of embodiment 1,2 preparations ₄Si ₃O ₁₂The photo of nanocrystalline specimen surface under scanning electronic microscope.

Embodiment

Embodiment 1,

The first step: the preparation of bismuthate glass

At first, impurity iron content less than the quartz sand of 10ppm and more than bismuthous oxide bismuth trioxide difference ball milling to 400 order, is made powder raw material; Then according to mol ratio Bi ₂O ₃: SiO ₂=2: 3 after bismuthous oxide bismuth trioxide powder and quartz sand powder mixed mixed powder;

Secondly, 30% of mixed powder is added the crucible of putting into the globars electric furnace in advance, charge temperature is 1020 ℃ for the first time, be incubated and add remaining mixed powder again after 10 minutes, be warming up to 1250 ℃ with 10 ℃/minute, close fire door, be incubated 1 hour, every 20 minutes crucible is taken out in the insulating process, adopt the high purity aluminium oxide rod that high-temperature fusant is stirred and put into stove immediately after 30 seconds; To found uniform glass metal after insulation finishes is that the fused mixed powder is poured on the stainless steel plate of room temperature, promptly obtains bismuthate glass after the cooling;

Second step: the Bi ₄Si ₃O ₁₂Nanocrystalline preparation

At first, prepared bismuthate glass is placed on the high purity aluminium oxide plate, and then alumina plate and bismuthate glass placed retort furnace together, be warming up to 900 ℃ of insulations 6 hours with 10 ℃/minute temperature rise rates from room temperature, be cooled to room temperature with 20 ℃/minute rate of temperature fall from 900 ℃ then, sample taken off from alumina plate promptly to get crystalline phase be Bi ₄Si ₃O ₁₂Nanocrystalline.Degree of crystallinity is 99%, by the Scherrer formula to the Bi among Fig. 1 ₄Si ₃O ₁₂Nanocrystalline size calculate prepared Bi ₄Si ₃O ₁₂Nanocrystalline mean sizes is 55nm.

Referring to accompanying drawing 1, prepared as can be seen crystal is the higher Bi of purity ₄Si ₃O ₁₂Nanocrystalline, accompanying drawing 2 (a) is prepared bismuth silicate Bi ₄Si ₃O ₁₂The SEM photo of nanocrystal surface, as can be seen from the figure, specimen surface has evenly been separated out the needle-like Bi of nano-scale ₄Si ₃O ₁₂Nanocrystalline.

Embodiment 2, the first step: the preparation of bismuthate glass

At first, impurity iron content less than the quartz sand of 10ppm and more than bismuthous oxide bismuth trioxide difference ball milling to 400 order, is made powder raw material; Then according to mol ratio Bi ₂O ₃: SiO ₂=2: 3 after bismuthous oxide bismuth trioxide powder and quartz sand powder mixed mixed powder;

Secondly, 30% of mixed powder is added the crucible of putting into the globars electric furnace in advance, charge temperature is 1020 ℃ for the first time, be incubated and add remaining mixed powder again after 15 minutes, be warming up to 1220 ℃ with 15 ℃/minute, close fire door, be incubated 1.5 hours, every 20 minutes crucible is taken out in the insulating process, adopt the high purity aluminium oxide rod that high-temperature fusant is stirred and put into stove immediately after 30 seconds; To found uniform glass metal after insulation finishes is that the fused mixed powder is poured on the stainless steel plate of room temperature, promptly obtains bismuthate glass after the cooling;

Second step: the Bi ₄Si ₃O ₁₂Nanocrystalline preparation

At first, prepared bismuthate glass is placed on the high purity aluminium oxide plate, and then alumina plate and bismuthate glass placed retort furnace together, temperature rise rate with 10 ℃ of part clocks is warming up to 900 ℃ of insulations 8 hours from room temperature, be cooled to room temperature with 20 ℃/minute rate of temperature fall from 900 ℃ then, sample taken off from alumina plate promptly to get crystalline phase be Bi ₄Si ₃O ₁₂Nanocrystalline.Degree of crystallinity is 98%, by the Scherrer formula to Bi ₄Si ₃O ₁₂Brilliant size calculate prepared Bi ₄Si ₃O ₁₂Average grain size is 54nm.

Accompanying drawing 2 (b) is prepared bismuth silicate Bi ₄Si ₃O ₁₂The SEM photo of nanocrystal surface, as can be seen from the figure, specimen surface has evenly been separated out the needle-like Bi of a large amount of nano-scales ₄Si ₃O ₁₂Nanocrystalline.

Embodiment 3, the first step: the preparation of bismuthate glass

At first, impurity iron content less than the quartz sand of 10ppm and more than bismuthous oxide bismuth trioxide difference ball milling to 400 order, is made powder raw material; Then according to mol ratio Bi ₂O ₃: SiO ₂=2: 3 after bismuthous oxide bismuth trioxide powder and quartz sand powder mixed mixed powder;

Secondly, 30% of mixed powder is added the crucible of putting into the globars electric furnace in advance, charge temperature is 1020 ℃ for the first time, be incubated and add remaining mixed powder again after 20 minutes, be warming up to 1200 ℃ with 20 ℃/minute, close fire door, be incubated 2 hours, every 20 minutes crucible is taken out in the insulating process, adopt the high purity aluminium oxide rod that high-temperature fusant is stirred and put into stove immediately after 30 seconds; To found uniform glass metal after insulation finishes is that the fused mixed powder is poured on the stainless steel plate of room temperature, promptly obtains bismuthate glass after the cooling;

Second step: the Bi ₄Si ₃O ₁₂Nanocrystalline preparation

At first, prepared bismuthate glass is placed on the high purity aluminium oxide plate, and then alumina plate and bismuthate glass placed retort furnace together, be warming up to 900 ℃ of insulations 10 hours with 10 ℃/minute temperature rise rates from room temperature, be cooled to room temperature with 20 ℃/minute rate of temperature fall from 900 ℃ then, sample taken off from alumina plate promptly to get crystalline phase be Bi ₄Si ₃O ₁₂Nanocrystalline.Degree of crystallinity is 97%, by the Scherrer formula to Bi ₄Si ₃O ₁₂Brilliant size calculate prepared Bi ₄Si ₃O ₁₂Average grain size is 59nm.

Embodiment 4, the first step: the preparation of bismuthate glass

At first, impurity iron content less than the quartz sand of 10ppm and more than bismuthous oxide bismuth trioxide difference ball milling to 400 order, is made powder raw material; Then according to mol ratio Bi ₂O ₃: SiO ₂=2: 3 after bismuthous oxide bismuth trioxide powder and quartz sand powder mixed mixed powder;

Secondly, 30% of mixed powder is added the crucible of putting into the globars electric furnace in advance, charge temperature is 1020 ℃ for the first time, be incubated and add remaining mixed powder again after 25 minutes, be warming up to 1250 ℃ with 25 ℃/minute, close fire door, be incubated 1.5 hours, every 20 minutes crucible is taken out in the insulating process, adopt the high purity aluminium oxide rod that high-temperature fusant is stirred and put into stove immediately after 30 seconds; To found uniform glass metal after insulation finishes is that the fused mixed powder is poured on the stainless steel plate of room temperature, promptly obtains bismuthate glass after the cooling;

Second step: the Bi ₄Si ₃O ₁₂Nanocrystalline preparation

At first, prepared bismuthate glass is placed on the high purity aluminium oxide plate, and then alumina plate and bismuthate glass placed retort furnace together, be warming up to 900 ℃ of insulations 12 hours with 10 ℃/minute temperature rise rates from room temperature, be cooled to room temperature with 20 ℃/minute rate of temperature fall from 900 ℃ then, sample taken off from alumina plate promptly to get crystalline phase be Bi ₄Si ₃O ₁₂Nanocrystalline.Degree of crystallinity is 96%, by the Scherrer formula to Bi ₄Si ₃O ₁₂Brilliant size calculate prepared Bi ₄Si ₃O ₁₂Average grain size is 58nm.

Embodiment 5, the first step: the preparation of bismuthate glass

At first, impurity iron content less than the quartz sand of 10ppm and more than bismuthous oxide bismuth trioxide difference ball milling to 400 order, is made powder raw material; Then according to mol ratio Bi ₂O ₃: SiO ₂=2: 3 after bismuthous oxide bismuth trioxide powder and quartz sand powder mixed mixed powder;

Secondly, 30% of mixed powder is added the crucible of putting into the globars electric furnace in advance, charge temperature is 1020 ℃ for the first time, be incubated and add remaining mixed powder again after 30 minutes, be warming up to 1180 ℃ with 15 ℃/minute, close fire door, be incubated 2 hours, every 20 minutes crucible is taken out in the insulating process, adopt the high purity aluminium oxide rod that high-temperature fusant is stirred and put into stove immediately after 30 seconds; To found uniform glass metal after insulation finishes is that the fused mixed powder is poured on the stainless steel plate of room temperature, promptly obtains bismuthate glass after the cooling;

Second step: the Bi ₄Si ₃O ₁₂Nanocrystalline preparation

At first, prepared bismuthate glass is placed on the high purity aluminium oxide plate, and then alumina plate and bismuthate glass placed retort furnace together, be warming up to 900 ℃ of insulations 9 hours with 10 ℃/minute temperature rise rates from room temperature, be cooled to room temperature with 20 ℃/minute rate of temperature fall from 900 ℃ then, sample taken off from alumina plate promptly to get crystalline phase be Bi ₄Si ₃O ₁₂Nanocrystalline.Degree of crystallinity is 98%, by the Scherrer formula to Bi ₄Si ₃O ₁₂Brilliant size calculate prepared Bi ₄Si ₃O ₁₂Average grain size is 53nm.

Embodiment 6, the first step: the preparation of bismuthate glass

At first, impurity iron content less than the quartz sand of 10ppm and more than bismuthous oxide bismuth trioxide difference ball milling to 400 order, is made powder raw material; Then according to mol ratio Bi ₂O ₃: SiO ₂=2: 3 after bismuthous oxide bismuth trioxide powder and quartz sand powder mixed mixed powder;

Secondly, 30% of mixed powder is added the crucible of putting into the globars electric furnace in advance, charge temperature is 1020 ℃ for the first time, be incubated and add remaining mixed powder again after 15 minutes, be warming up to 1150 ℃ with 18 ℃/minute, close fire door, be incubated 1 hour, every 20 minutes crucible is taken out in the insulating process, adopt the high purity aluminium oxide rod that high-temperature fusant is stirred and put into stove immediately after 30 seconds; To found uniform glass metal after insulation finishes is that the fused mixed powder is poured on the stainless steel plate of room temperature, promptly obtains bismuthate glass after the cooling;

Second step: the Bi ₄Si ₃O ₁₂Nanocrystalline preparation

At first, prepared bismuthate glass is placed on the high purity aluminium oxide plate, and then alumina plate and bismuthate glass placed retort furnace together, be warming up to 900 ℃ of insulations 11 hours with 10 ℃/minute temperature rise rates from room temperature, be cooled to room temperature with 20 ℃/minute rate of temperature fall from 900 ℃ then, sample taken off from alumina plate promptly to get crystalline phase be Bi ₄Si ₃O ₁₂Nanocrystalline.Degree of crystallinity is 99%, by the Scherrer formula to Bi ₄Si ₃O ₁₂Brilliant size calculate prepared Bi ₄Si ₃O ₁₂Average grain size is 49nm.

The present invention adds raw material by high temperature, and high temperature melts rapidly, and technologies such as high-temperature stirring are accelerated the glass metal that mixed powder forms congruent melting fast.The present invention is at preparation Bi ₄Si ₃O ₁₂Do not add nucleator and other additive when nanocrystalline, prepared Bi ₄Si ₃O ₁₂Nanocrystalline grain-size is little, is shaped as needle-like or bar-shaped, and size is even, the degree of crystallinity height, and the crystal purity height, dephasign is few, and cost of material is cheap, and the source is abundant, and synthesis temperature is lower, and preparation technology is simple, helps suitability for industrialized production.Prepared Bi ₄Si ₃O ₁₂The nanocrystalline magnetron sputtering that can be used as prepares Bi ₄Si ₃O ₁₂The high purity target of film and preparation high quality Bi ₄Si ₃O ₁₂The raw material of macrocrystal.

Claims (2)

1. Bi ₄Si ₃O ₁₂Preparation of nano crystal is characterized in that:

The first step: the preparation of bismuthate glass

At first, with quartz sand and more than bismuthous oxide bismuth trioxide difference ball milling to 400 order, make powder raw material; Then according to mol ratio Bi ₂O ₃: SiO ₂=2: 3 after bismuthous oxide bismuth trioxide powder and quartz sand powder mixed mixed powder;

Secondly, 30% of mixed powder is added the crucible of putting into the globars electric furnace in advance, charge temperature is 1020 ℃ for the first time, be incubated and add remaining mixed powder again after 10～30 minutes, be warming up to 1150～1250 ℃ with 10～25 ℃/minute, close fire door, be incubated 1～2 hour, every 20 minutes crucible is taken out in the insulating process, adopt the high purity aluminium oxide rod that high-temperature fusant is stirred and put into stove immediately after 30 seconds; To found uniform glass metal after insulation finishes is that the fused mixed powder is poured on the stainless steel plate of room temperature, promptly obtains bismuthate glass after the cooling;

Second step: the Bi ₄Si ₃0 ₁₂Nanocrystalline preparation

At first, prepared bismuthate glass is placed on the high purity aluminium oxide plate, and then alumina plate and bismuthate glass placed retort furnace together, be warming up to 900 ℃ of insulations 6～12 hours with 10 ℃/minute temperature rise rates from room temperature, be cooled to room temperature with 20 ℃/minute rate of temperature fall from 900 ℃ then, sample taken off from alumina plate promptly to get crystalline phase be Bi ₄Si ₃O ₁₂Nanocrystalline.

2. Bi according to claim 1 ₄Si ₃O ₁₂Preparation of nano crystal is characterized in that: said SiO ₂Introduce by quartz sand, impurity iron content is less than 10ppm.

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