CN1276358A - Process for preparing low-carbon superfine REBa2Cu3O6+ delta powder - Google Patents

Abstract

A process for preparing low-carbon superfine REBa2Cu3O6+delta powder as the raw power of REBCO superconductor with high Jc value includes such steps as proportional mixing BaCO3 with CuO, sintering to obtain BaCuO2 powder, proportional mixing with RExOy and CuO powder and sintering at 870-920 deg.C in flowing oxygen atmosphere. Its advantages are low content of carbon, low average size less than 1 micron, and simple preparing process.

Description

A kind of low-carbon superfine REBa 2Cu 3O 6+ δThe preparation method of powder

A kind of low-carbon superfine REBa ₂Cu ₃O _{6+ δ}The preparation method of powder relates to a kind of REBa that adopts the melting texture legal system to be equipped with the basic raw material of high Jc value REBCO superconductor ₂Cu ₃O _{6+ δ}The preparation method of powder.

REBa ₂Cu ₃O _{6+ δ}Powder is the basic raw material that the melting texture legal system is equipped with high Jc value REBCO superconductor.Its basic demand is: one, carbon content low (＜300ppm), will seriously reduce its superconductivity because in a single day carbon enter the REBCO lattice; Two, granularity is wanted thin (best＜1 μ m), because high Jc value REBCO requires to have a large amount of ultra-fine RE ₂BaCuO ₅(＜1 μ m) is distributed in to even dispersion in the REBCO matrix strengthening pinning and to eliminate crackle eliminating weak connection, and RE ₂BaCuO ₅Derive from REBa ₂Cu ₃O _{6+ δ}The peritectoid decomposition course of powder, in the peritectoid decomposition course, RE ₂BaCuO ₅At original REBa ₂Cu ₃O _{6+ δ}If the grain boundary forming core is original REBa ₂Cu ₃O _{6+ δ}Crystal grain (powder) is enough thin, and then grain boundary area is enough big, RE in the peritectoid decomposition course ₂BaCuO ₅The nucleation site is also just more, REBa ₂Cu ₃O _{6+ δ}Crystal grain (powder) decomposes back gained RE fully ₂BaCuO ₅Size is more tiny, thus in texturing REBCO peritectoid building-up process subsequently captive RE ₂BaCuO ₅Size is also just more tiny, and then obtains the REBCO superconductor of high Jc value.Prepare REBa at present ₂Cu ₃O _{6+ δ}Powder often adopts solid-state sintering and wet-chemical reaction method (as coprecipitation method, melting glue-gel method).Because BaO is extremely unstable, is easy in air and CO ₂Reaction generates BaCO ₃So classical solid-state sintering often adopts commodity rare earth oxide RExOy, BaCO ₃With three kinds of powder of CuO as raw material, press stoicheiometry mixed evenly after, sintering in circulation oxygen atmosphere more than 900 ℃.For guaranteeing BaCO ₃Decompose fully to obtain the REBa of low carbon content ₂Cu ₃O _{6+ δ}, often need sintering more than 50 hours.Since at high temperature the reaction times long, the REBa of generation ₂Cu ₃O _{6+ δ}Often grow up into tens of microns.And the wet-chemical reaction method generally is to separate out REBa in carbonaceous organic solvent ₂Cu ₃O _{6+ δ}, then at long-time sintering more than 900 ℃ to remove the carbon that organic solvent is introduced, REBa in this process ₂Cu ₃O _{6+ δ}Very easily grow up into tens of micron, have a negative impact preparing high Jc value REBCO superconductor, and also relative complex of technological process.

Purpose of the present invention is exactly in order to overcome the deficiency that above-mentioned prior art exists, the preparation process easy handling to be provided, and can effectively reduce carbon content, effectively control REBa ₂Cu ₃O _{6+ δ}A kind of low-carbon superfine REBa of the fineness of powder ₂Cu ₃O _{6+ δ}The preparation method of powder provides high quality raw material for adopting the melting texture legal system to be equipped with high Jc value REBCO superconductor.

The objective of the invention is to be achieved through the following technical solutions.

A kind of low-carbon superfine REBa ₂Cu ₃O _{6+ δ}The preparation method of powder, it is characterized in that its preparation process is: a. is at first with BaCO ₃With CuO by after the preparation of 1: 1 mol ratio and mixing, between 870 ℃-920 ℃ in the circulation oxygen atmosphere sintering 40-50 hour, prepare BaCuO ₂Powder; B. with the BaCuO that bakes ₂Levigate and with rare earth oxide RExOy, CuO powder be that 1: 2: 3 proportioning mixes by RE: Ba: Cu; C. with the powder that mixes between 870 ℃-920 ℃ in the circulation oxygen atmosphere after sintering 10-20 hour, through levigate REBa ₂Cu ₃O _{6+ δ}The end.

Method of the present invention is compared with the wet-chemical reaction method with classical solid-state sintering, adopts the carbon of removing earlier in the process, and synthetic REBa ₂Cu ₃O _{6+ δ}Step in carbon do not participate in reaction, therefore not only can reduce the carbon content of powder, can also avoid REBa ₂Cu ₃O _{6+ δ}Too growing up at high temperature, thus the ultra-fine REBa of low carbon content obtained ₂Cu ₃O _{6+ δ}Powder.Prepared REBa ₂Cu ₃O _{6+ δ}Powder mean particle sizes is less than 1 μ m, and simple to operate, is a kind of more satisfactory REBa ₂Cu ₃O _{6+ δ}The preparation method of powder.

Below in conjunction with embodiment method of the present invention is described further.

A kind of low-carbon superfine REBa ₂Cu ₃O _{6+ δ}The preparation method of powder specifically divides three steps: the first step, preparation BaCuO ₂Powder.Adopt conventional process, with BaCO ₃With CuO by after the preparation of 1: 1 mol ratio and mixing, between 870 ℃-920 ℃ in the oxygen atmosphere that circulates sintering 40-50 hour; Second step is with the BaCuO that bakes ₂With rare earth oxide RExOy, CuO powder be 1: 2: 3 preparation back ball milling a few hours by RE: Ba: Cu, make BaCuO ₂Broken and mix with rare earth oxide RExOy, CuO; The 3rd step just finished reaction in sintering 10-20 hour in the circulation oxygen atmosphere between 870 ℃-920 ℃ in the powder that mixes, and ball mill crushing gets final product then.Prepared REBa ₂Cu ₃O _{6+ δ}Powder mean particle sizes is less than 1 μ m.

Method of the present invention, its basic thought are to remove earlier carbon elimination, are about to BaCO ₃At first be converted into carbon-free BaCuO ₂Steady oxide is used carbon-free BaCuO then ₂With the synthetic REBa of rare earth oxide RExOy, CuO reaction ₂Cu ₃O _{6+ δ}Because synthetic REBa ₂Cu ₃O _{6+ δ}There is not BaCO in the direct reaction process ₃Decomposition reaction, so the sintering time under the high temperature can shorten greatly.As long as control sintering temperature and sintering time well reaction is just finished and the REBa that generates ₂Cu ₃O _{6+ δ}Within reason again growing up just may be prepared the REBa of superfine low carbon content ₂Cu ₃O _{6+ δ}Powder.

Embodiment 1:

With BaCO ₃After the CuO powder mixes by mol ratio preparation in 1: 1, in tube furnace, be warming up to 900 ℃ of insulations 1 hour after 10 hours, be warming up to 920 ℃ of sintering 30 hours again in 870 ℃ of sintering in the circulation oxygen atmosphere, obtain BaCuO ₂Powder.With BaCuO ₂With Y ₂O ₃, the CuO powder mixes the back in 870 ℃ of sintering 20 hours by the preparation of 4: 1: 2 mol ratios.Again with the powder of gained with agate ball grinding machine ball milling 2 hours, obtain carbon content and be lower than 200ppm, mean particle size ultra-fine YBa less than 1 μ m ₂Cu ₃O _{6+ δ}Powder.

Embodiment 2:

With BaCO ₃After the CuO powder mixes by mol ratio preparation in 1: 1, in tube furnace, be warming up to 900 ℃ of insulations 1 hour after 10 hours, be warming up to 920 ℃ of sintering 30 hours again in 870 ℃ of sintering in the circulation oxygen atmosphere, obtain BaCuO ₂Powder.With BaCuO ₂With Y ₂O ₃, the CuO powder mixes the back in 900 ℃ of sintering 14 hours by the preparation of 4: 1: 2 mol ratios.Again with the powder of gained with agate ball grinding machine ball milling 2 hours, obtain carbon content and be lower than 200ppm, mean particle size ultra-fine YBa less than 1 μ m ₂Cu ₃O _{6+ δ}Powder.As shown in Figure 1.

Embodiment 3:

With BaCO ₃After the CuO powder mixes by mol ratio preparation in 1: 1, in tube furnace, be warming up to 900 ℃ of insulations 1 hour after 10 hours, be warming up to 920 ℃ of sintering 30 hours again in 870 ℃ of sintering in the circulation oxygen atmosphere, obtain BaCuO ₂Powder.With BaCuO ₂With Y ₂O ₃, the CuO powder mixes the back in 920 ℃ of sintering 10 hours by the preparation of 4: 1: 2 mol ratios.Again with the powder of gained with agate ball grinding machine ball milling 2 hours, obtain carbon content and be lower than 200ppm, mean particle size ultra-fine YBa less than 1 μ m ₂Cu ₃O _{6+ δ}Powder.

Claims (6)

1. low-carbon superfine REBa ₂Cu ₃O _{6+ δ}The preparation method of powder is characterized in that its preparation process is:

A. at first with BaCO ₃With CuO by after the preparation of 1: 1 mol ratio and mixing, between 870 ℃-920 ℃ in the circulation oxygen atmosphere sintering 40-50 hour, prepare BaCuO ₂Powder;

B. with the BaCuO that bakes ₂Levigate and with rare earth oxide RE _xO _y, the CuO powder is that 1: 2: 3 proportioning mixes by RE: Ba: Cu;

C. with the powder that mixes between 870 ℃-920 ℃ in the circulation oxygen atmosphere after sintering 10-20 hour, through levigate REBa ₂Cu ₃O _{6+ δ}Powder.

2. method according to claim 1 is characterized in that rare earth oxide Re _xO _yBe Y ₂O ₃

3. method according to claim 1 is characterized in that rare earth oxide Re _xO _yBe Nd ₂O ₃

4. method according to claim 1 is characterized in that rare earth oxide Re _xO _yBe Sm ₂O ₃

5. method according to claim 1 is characterized in that rare earth oxide Re _xO _yBe Yb ₂O ₃

6. method according to claim 1 is characterized in that BaCuO ₂With rare earth oxide Y ₂O ₃, the CuO powder mixes is sintering after 14 hours in 900 ℃ of circulation oxygen atmospheres after evenly.