JPS63222063A - Production of ceramics - Google Patents

Abstract

PURPOSE:To obtain high-temperature superconducting oxide based ceramics, useful as a superconducting material, etc., by reacting a mixture of three consisting of respective (hydro)oxides or oxyacid salts of group III-a and II-a metals of the periodic table and copper, iron, Co, etc., by impact compression caused by explosion. CONSTITUTION:Three of (A) oxides, hydroxides or oxyacid salts of a group III-a metal of the periodic table (e.g. Sc2O3 or Y2O3) and (B) oxides, hydroxides or oxyacid salts of a group III-a metal of the periodic table (e.g. SrCO3 or BaO) and (C) oxide, hydroxide or oxyacid salt of one of Cu, Fe, Co and Ni are blended at a ratio according to a desired element constituent ratio of ceramics and the resultant blend, as necessary, is heat-treated at 600-1,200 deg.C in air or O2 atmosphere under 1.0X10<-8>-1atm. pressure for 1-24hr. A reaction raw material 2, such as the resultant powder blend, is placed in a metallic cylinder 1, closed with a metallic plug 3 and evacuated by an evacuation pipe 4, which is then is sealed. The periphery thereof is subsequently covered with 100g-5kg explosive 5 based on 1-500g raw material and exploded through an electric detonator 7 at the tip of an external vessel 6 to carry out reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for manufacturing oxide-based ceramics using explosive impact compression.

(Industrial Application Field) Oxide-based ceramics composed of elements of group M-A of the periodic table such as yttrium and lanthanum, elements of group II-a of the periodic table such as barium and strontium, and copper and oxygen have 30 or more dislocations. It has recently attracted attention as a superconducting material with a temperature Tc, and can be applied to various wire materials such as low-loss superconducting wires, superconducting magnets, Josephson elements, and electromagnetic equipment and devices, making it extremely useful in industry. It is for use.

(Prior art and problems) Conventional La-Ba-Cu-0 system, La = Sr-Cu
The -0 series ceramic superconductor is composed of polycrystalline grains having superconducting characteristics, and the superconducting phenomenon is thought to be due to percolation between the grains via grain boundaries.

Therefore, it is thought that the original superconducting properties of the material are not fully expressed. For example, La+-9BaXCu0
3-y (x = 0.20 or 0.15) has a transition temperature Tc of 32 under normal pressure, and in order to raise it to 40K, a pressure of 13 Kbar must be applied.

Furthermore, it is known that for La+, eSro, and CuO4, since the sample is porous, the magnetic susceptibility due to diamagnetic property exhibits only 60 to 70% of that of an ideal superconductor.

Therefore, it is necessary to reduce voids in the material and prevent deterioration of superconducting properties due to grain boundaries between grains.

(Means for Solving the Problem) In view of these problems, the present inventors have conducted repeated studies to prevent deterioration of superconducting properties due to grain boundaries between grains of superconducting ceramic materials. I have found a method.

That is, according to the present invention, an oxide, hydroxide or oxyacid of a metal of group M-a of the periodic table, an oxide, hydroxide or oxyacid of a metal of group II-a of the periodic table, and any of copper, cobalt, and nickel. chemically reacting a mixture M of one of the three oxides, hydroxides, or oxyacids by impact compression accompanying an explosion, or as a mixture M 600 to 1200
Applying impact compression treatment due to explosion using mixture M'' that has been heat treated at ℃, or applying impact compression treatment due to explosion using mixture M'' that has been molded and sintered at 600 to 1200℃. The present invention relates to a method for manufacturing ceramics, which is characterized in that the method comprises:

In the present invention, the oxide-based ceramic can be synthesized by impact-compressing a mixture of constituent metal salts at a predetermined molar ratio through explosion.

First, as a metal source of group ■-a of the periodic table, La20: ++
La(Of+)+, La(NO3)3. Laz(CO3
):++ Y2O3+ Y(011)31Y(NO3)
31 Yz(COi), l, 5czOs+ 5C(01
1): II 5c (N03)a.

5c2(COa)a+ Ce2O3, Ce(OH)3
．． Ce(NOa)3+Cez(CO3)3. N
d2o3. Nd(O)l)3. Nd(NOa)3゜Nd2(CO3):++ Sm2O3, Sm(OH)
:++ Sm(NO3)3+Smz(CO3)3
etc. As a group II-a metal source of the periodic table, B
aC0, , Ba(NO:+)z, BaO+ Ba0z
+5rCC1++5r(NO:+)z, sro, 5
rOz, CaC0,, Ca(NOs)zlCab.

Examples include CaO2. In addition, as sources of copper, iron, cobalt, and nickel, Cub, Cu2O, Cu2O3+
Cu (OtD 21C[I(NO3)21 Fed
, FezO:++ Fe(011)z, Fe(N
Oz)z.

Fe(NO3)3. FeC0a+ Cool COO
31Co(OH)21 Nl0IN+ (OH) 21
Examples include Nl (NO3) 21 NIC03.

The three types of metal salt mixture M serving as a starting material is prepared in accordance with the elemental composition ratio of the desired ceramic compound. For example, in the case of lal, s Bao, 2C1104, 1.8 mol of the above lanthanum compound, 0.2 mol of the above barium compound, and 1.0 mol of the above copper compound powders were mixed evenly and used. do.

The composition ratio of each element in the ceramic compound is αt, β8γδ3-y, α2-xβxγδa-y, or α5. ,
Group metal 1 γ is one of Cu, Fe+ Go+ Nj, δ is O; 0.05 ≦x ≦1.0.
y;i=0) It is desirable that there be, but the present invention is not limited to this.

Chemical reactions and grain boundary control due to impact compression during explosion occur within an extremely short time of several microseconds to 100 microseconds. Therefore, when using the mixture M of each metal compound powder as a reaction raw material, it is desirable to grind it sufficiently finely in order to increase reaction efficiency and form grain boundaries between grains. Preferably, it is made into a fine powder of 325 meshes (43 microns) or less.

More preferably, in order to eliminate grain boundaries between grains, instead of mixture M, mixture M is used at 1.0×10−
'~1 atm air or oxygen atmosphere, 600~120
It is preferable to use a powder mixture M' that has been heat-treated at 0°C for 1 to 24 hours.

More preferably, the heat-treated mixture M'' is formed by pressing or the like and sintered at 600 to 1200°C for 5 hours to 6 days.

The shape of the reaction product may be cylindrical, pellet, rectangular, thin plate, thin film, needle, or linear.

Reaction devices using shock compression accompanying explosions (hereinafter referred to as shock synthesis devices) include a conical device used by Person, a planar shock wave generator used by DeCarl+ and Jamieson, and an impact gun. , a device using a flying plate, a cylindrical device using a cylindrical shock wave, etc. can be used.

A manufacturing method using a device that utilizes cylindrical shock waves will be described below as an example.

The drawing shows a shock compression reaction device (hereinafter referred to as a shock synthesis device) using cylindrical shock waves.

A molded and sintered mixture M, a heat-treated mixture M'', or a heat-treated mixture M'' as a reaction raw material is placed in a metal cylinder 1.The cylinder 1 is equipped with an exhaust vibrator 4, and the reaction raw material is placed in the metal cylinder 1. After covering the cylinder with a stopper 3 and evacuating it, a vibrator 4 is welded and sealed.
The surrounding area is covered with explosives 5, and an electric detonator 7 is attached to the top of the outer container 6.
will be established. The ceramic of the present invention can be obtained by detonating the explosive 5 using the electric detonator 7 and collecting the reaction product.

The amount of explosive depends on the amount of reactants, but between 1 and 50
Use 100g to 5kg for 0g. The pressure applied by the explosion is 5,000 atm to 2,500,000 atm, and the explosion speed is 1 km/sec to 5 km/sec.
It is calculated that the metal compounds react with each other under extremely high temperature and pressure.

Many of the ceramics produced by the production method of the present invention exhibit properties as high-temperature superconductors. for example,
SC1,7Sro, +C synthesized by the method of the present invention
u0t-y(y>O) is 311, Yo, 4Bao,
6Cub3 is 280, Lao, a Bao, z
CuO+-y (y>O) shows signs of superconductivity at 215K (-40°C). Also, SC1, 7Sro, +C
u0a-y (y>0) is 295 and exhibits perfect diamagnetism characteristic of the superconducting state.

(Effects of the Invention) According to the production method of the present invention, it is possible to produce a high-temperature superconducting ceramic material that operates at a higher temperature than before by impact synthesis.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 1.46 g of scandium oxide (SC203), 0.55 g of strontium carbonate (SrCOs), and 0.99 g of copper (I[) (Cub) oxide were thoroughly mixed, and
．． Heat treatment was performed at 900° C. for 5 hours in an oxygen atmosphere of 0.2 Torr (2.5×10 −5 atmospheres). This heated product was formed into a cylindrical pellet at a pressure of 4 Kbar,
Sintering was performed at 900° C. for 24 hours in an oxygen atmosphere of 0.02 Torr. The sintered pellet was packed into a metal cylinder 1 of an impact synthesis device, covered with a metal stopper 3, the inside was evacuated, and a vibrator 4 was sealed. This reaction container was placed in an outer container 6, and the surrounding area was covered with 400 g of explosive 5. After ignition and explosion using an electric detonator 7, 2.8 g of ceramic product was recovered.

The product pellet was cut into a rectangle, four terminals were provided with an Au electrode and an In wire, and the specific resistance was measured while cooling in a Taraviostat. Specific resistance ρ at 350K (350
) Ratio of specific resistance at each absolute temperature ρ(T)/ρ
When (350) was measured, it started to decrease rapidly from 311K and showed a value close to zero at 298. Furthermore, when the magnetic susceptibility χ was measured while being cooled, it began to rapidly increase in the negative direction from 305 K, indicating diamagnetic properties. The magnetic susceptibility χ reached a minimum at 295, and the value of the magnetic susceptibility χ at this time was 98% of the value of perfect diamagnetism calculated for an ideal superconductor having the same volume.

Example 2 Yttrium oxide (Yz(L+) 0.94 g, barium carbonate (BaCO3) 1.23 g, copper oxide (II
) (Cub) 0.83 g was thoroughly ground and mixed,
Heat treatment, molding and sintering were performed in the same manner as in Example 1, and impact compression by explosion was performed.

2.75 g of product was recovered. ρ(T)/ρ(
When the temperature dependence of 350) was measured, it began to rapidly decrease with cooling from 280 K, and at 272 it showed a value close to zero.

Example 3 Lanthanum hydroxide (La(OH)3) 1.63g, barium(II) oxide (Bad) 0.38g, copper oxide (
If ) (Cub) 0.99 g was thoroughly ground and mixed, and heat-treated at 900° C. for 6 hours in an oxygen atmosphere of 0.02 Torr (2.5 xio-5 atm). This heated product was packed into the metal cylinder 1 of an impact synthesis device and subjected to impact compression by explosion in the same manner as in Example 1.2.
95g of product was collected. When the temperature dependence of ρ(T)/ρ(350) was investigated, it began to decrease rapidly with cooling from 215k, and at 200k it showed a value close to zero.

Example 4 2.19 g of lanthanum oxide (LazO3), 0.22 g of strontium carbonate (SrC(L+)), and 0.59 g of copper(II) oxide (CuO) were thoroughly ground and mixed, and the mixture was placed in a metal cylinder of an impact synthesis device. 1 and subjected to impact compression by explosion in the same manner as in Example 1. 2.85 g of product was recovered. When the temperature dependence of ρ (T)/ρ (350) was measured, it was found that from 220 K with cooling. It started to decrease rapidly and reached a value close to zero at 203.

Example 5 Yttrium oxide (Y2O2) 1.52 g, strontium carbonate (SrC(h) 0.27 g, copper oxide (I
I) (Cub) 1.21g was thoroughly ground and mixed,
Heat treatment, molding and sintering were performed in the same manner as in Example 1, and impact compression by explosion was performed. 2.95g of product was recovered. When the temperature dependence of ρ (T)/ρ (350) was measured, it began to rapidly decrease with cooling from 295 K, and at 282 it showed a value close to zero.

Example 6 Scandium oxide (SC203) 1. ．． 66 g,
0.27 g of calcium carbonate (CaCO3) and 1.07 g of iron oxide (m) (pezoa) were thoroughly ground and mixed, and heat treated, shaped and sintered in the same manner as in Example 1,
Shock compression was performed by explosion. As product, 2.7g
was recovered. When the temperature dependence of ρ(T)/ρ(350) was measured, it began to rapidly decrease with cooling from 195K, and at 173, it showed a value close to zero.

Example 7 Lithium oxide (YzO,J) 1.90 g,
Strontium carbonate (SrC(h) o, 31 g
, 0.79 g of nickel oxide (IT) (NiO) were sufficiently pulverized and mixed, subjected to heat treatment, molding and sintering in the same manner as in Example 1, and subjected to impact compression by explosion. 2.75 g of product was recovered. When the temperature dependence of ρ(T)/ρ(350) was measured, it began to rapidly decrease with cooling from 182 K, and at 177 it showed a value close to zero.

[Brief explanation of the drawing]

The drawing is a sectional view of the impact synthesizer. In the figure, 1 is a metal cylinder, 2 is a reaction raw material, 3 is a metal frame, 4 is an exhaust pipe, 5 is an explosive, 6 is an outer container, and 7 is an electric detonator. 71? Applicant: Asahi Kasei Kogyo Company, Ltd. Figure 7-', 7

Claims (1)

[Claims] Oxides, hydroxides, or oxyacids of metals of Group III-a of the Periodic Table; oxides, hydroxides, or oxyacids of metals of Group II-a of the Periodic Table; and any of copper, iron, cobalt, and nickel A method for producing ceramics, which comprises chemically reacting a mixture of oxides, hydroxides, or oxyacids with each other through impact compression accompanied by an explosion.