A kind of cubic perovskite structure BaRuO
3Crystal and preparation method thereof
Technical field
The present invention relates to a kind of cubic perovskite structure BaRuO
3Crystal and preparation method thereof particularly relates to a kind of single-phase cubic perovskite structure BaRuO of high temperature and high pressure method synthetic that utilizes
3Crystal and prepare this crystalline high temperature and high pressure method.
Background technology
In recent years, because ru oxide has the character of a lot of novelties, people have launched extensive studies work to it.ARuO
3(A=Ca, Sr, Ba) is an important system in the ru oxide, SrRuO
3And CaRuO
3Belong to perovskite structure, spacer is Pbnm.The former is a ferromagnetic metal, and the latter is a paramagnetic metal.Because Ba
2+Ion and Ru
4+It is bigger that ionic radius differs, BaRuO
3Be difficult for forming perovskite structure, and form six sides (or tripartite) laminate structure easily.Its normal pressure phase (9R-BaRuO
3) be a kind of material with counterfeit energy gap.BaRuO
3There are three kinds of laminate structure: 9R, 4H and 6H, wherein, BaO in the numeral structure cell
3The planar number, the letter representation structure type).9R-BaRuO
3Can obtain by the solid state reaction under the normal pressure mutually, be trigonal crystal structure, its spacer is R-3m; 4H-BaRuO
3And 6H-BaRuO
3Can pass through mutually 9R-BaRuO
3Carry out high temperature high pressure process mutually and obtain, they are hexagonal structure, and its spacer is P6
3/ mmc.
But a difficult problem of failing to overcome at present is to synthesize the BaRuO of monophasic cubic perovskite structure
3Crystal, thus can not characterize its structure and rerum natura.Because pressure is suitable for the uhligite material of Metacentre Height densification very much, is bringing into play in the research of material and important effect, be the important means of development ru oxide, so, based on this, for overcoming this difficult problem, we have adopted the High Temperature High Pressure synthetic method, by to 9R-BaRuO
3Carry out high temperature high pressure process mutually, it is changed into and SrRuO
3The BaRuO of the different single-phase cubic perovskite structure of orthohormbic structure
3Crystal, and make its crystalline structure of research and physical properties become possibility.
Summary of the invention
One of purpose of the present invention provides a kind of BaRuO of monophasic cubic perovskite structure
3Crystal, this crystal are by handling monophasic 9R-BaRuO under High Temperature High Pressure
3Synthetic.
Another object of the present invention provides a kind of BaRuO of single-phase cubic perovskite structure
3The crystalline preparation method.
To achieve these goals, the present invention has adopted following technical scheme:
The invention provides a kind of BaRuO of monophasic cubic perovskite structure
3Crystal, its spacer are Pm-3m, and unit cell parameters is: a=4.004
The invention provides a kind of BaRuO of single-phase cubic perovskite structure
3Crystalline preparation method, this method adopt the solid state chemistry method to prepare monophasic 9R-BaRuO earlier
3Utilize high-temperature and high-pressure conditions to handle monophasic 9R-BaRuO then
3, synthesize the BaRuO of single-phase cubic perovskite structure then through quenching
3Crystal, above-mentioned high-temperature and high-pressure conditions is: 900 ℃-1100 ℃ of temperature, preferred 950 ℃-1050 ℃, more preferably 1000 ℃; Pressure 16-20GPa, preferred 18GPa; Soaking time is more than 30 minutes.
The BaRuO of above-mentioned single-phase cubic perovskite structure
3Among the crystalline preparation method, described solid state chemistry method is prepared single-phase 9R-BaRuO
3Concrete steps comprise:
Utilize solid state reaction under the normal pressure, with chemical pure BaCO
3(purity is not less than 99.9%) and Ru powder were with 1: 1 mixed in molar ratio, grinding, under 900 ℃-1000 ℃ condition, carry out first sintering, insulation is more than 12 hours, under 1100 ℃-1200 ℃ condition, carry out the sintering second time then, insulation is more than 24 hours, perhaps repeat sintering repeatedly the second time in the agglomerating temperature range again, preferred 2 times, finally obtain monophasic 9R-BaRuO
3
Wherein, preferred 1100 ℃ of sintering temperature for the second time.
The BaRuO of above-mentioned single-phase cubic perovskite structure
3Among the crystalline preparation method, high temperature and high pressure method is handled single-phase 9R-BaRuO
3Concrete steps comprise:
With the single-phase 9R-BaRuO that obtains under the normal pressure
3The sequin that is pressed into, preferred diameter is that 1.5mm, thickness are 2mm, and with goldleaf or platinum foil parcel, this sample is put into the tantalum well heater, carries out height in the high pressure assembly of packing into and is pressed into, the medium of using in the tantalum well heater is magnesium oxide and zirconium white.Sample synthesizes on the big press of six-eight types and carries out, and at room temperature slowly boosts to 18GPa earlier, restarts heating schedule and is heated to 900 ℃-1100 ℃, is incubated then more than 30 minutes, is quenched to room temperature, release then (1GP,a=1 ten thousand normal atmosphere).
Wherein, before High-Voltage Experimentation, preferably carry out the demarcation of temperature and pressure, and control Heating temperature and utilize the chromel-alumel thermocouple to measure temperature with the method for control heating power.
Utilize high-temperature and high-pressure conditions of the present invention, can be to the single-phase 9R-BaRuO of synthetic under the normal pressure
3Handle, thereby prepare the BaRuO of monophasic cubic perovskite structure
3Crystal, this crystal structure quality is good, turns out to be single-phasely through X-ray diffraction, and its physical structure and performance is tested.
Description of drawings
Below in conjunction with drawings and Examples the present invention is done description further:
Fig. 1 is the device synoptic diagram of High Temperature High Pressure synthetic sample of the present invention.
Fig. 2 is that high pressure of the present invention prepares cubic perovskite structure BaRuO
3The XRD figure spectrum of sample has been carried out indexing to main diffraction peak among the figure.
Fig. 3 is the cubic perovskite structure BaRuO of high temperature and high pressure method preparation of the present invention
3The susceptibility of sample concerns that with variation of temperature illustration is its magnetic hysteresis loop when 5K.
Fig. 4 is the cubic perovskite structure BaRuO of high temperature and high pressure method preparation of the present invention
3The resistivity of sample concerns that with variation of temperature illustration is at T
CFollowing resistivity and T
2Linear relationship.
Embodiment
Embodiment 1
1) under the normal pressure, utilize the solid state chemistry method to prepare monophasic 9R-BaRuO
3
Utilize solid state reaction, with the BaCO of 99.9% purity
3With mixed in molar ratio, the grinding with 1: 1 of the Ru powder of 99.9% purity, sintering under 900 ℃ condition is incubated 12 hours.Sintering 3 times under 1100 ℃ condition is incubated 24 hours at every turn then, just can obtain monophasic 9R-BaRuO
3Crystal.
2) utilize high temperature and high pressure method to synthesize the BaRuO of monophasic cubic perovskite structure
3Crystal.
With the single-phase 9R-BaRuO that obtains under the normal pressure
3The sequin that is pressed into, preferred diameter is that 1.5mm, thickness are 2mm, and with goldleaf or platinum foil parcel, this sample is put into the tantalum well heater, carries out height in the high pressure assembly of packing into and is pressed into, the medium of using in the tantalum well heater is magnesium oxide and zirconium white.Sample synthesizes on the big press of six-eight types and carries out, and at room temperature slowly boosts to 16GPa earlier, restarts heating schedule and is heated to 1000 ℃, is incubated 60 minutes then, is quenched to room temperature, release then (1GP,a=1 ten thousand normal atmosphere).
The sample that the back of quenching is obtained carries out X-ray diffraction studies, the results are shown among Fig. 2, turns out to be the BaRuO of monophasic cubic perovskite structure
3Crystal, crystalline quality is better, and its spacer is Pm-3m, and unit cell parameters is a=4.004
The magnetic hysteresis loop of its susceptibility during with variation of temperature and 5K is shown among Fig. 3.Fig. 4 shows its resistivity and concerns with variation of temperature, and illustration is at T
CFollowing resistivity and T
2Linear relationship.
Embodiment 2
1) under the normal pressure, utilize the solid state chemistry method to prepare monophasic 9R-BaRuO
3
Utilize solid state reaction, with the BaCO of 99.9% purity
3With mixed in molar ratio, the grinding with 1: 1 of the Ru powder of 99.9% purity, sintering under 1000 ℃ condition is incubated 12 hours.Sintering 3 times under 1100 ℃ condition is incubated 24 hours at every turn then, just can obtain monophasic 9R-BaRuO
3
2) utilize high temperature and high pressure method to synthesize the BaRuO of monophasic cubic perovskite structure
3Crystal.
With the single-phase 9R-BaRuO that obtains under the normal pressure
3The sequin that is pressed into, preferred diameter is that 1.5mm, thickness are 2mm, and with goldleaf or platinum foil parcel, this sample is put into the tantalum well heater, carries out height in the high pressure assembly of packing into and is pressed into, the medium of using in the tantalum well heater is magnesium oxide and zirconium white.Sample synthesizes on the big press of six-eight types and carries out, and at room temperature slowly boosts to 18GPa earlier, restarts heating schedule and is heated to 1100 ℃, is incubated 30 minutes then, is quenched to room temperature, release then (1GP,a=1 ten thousand normal atmosphere).
With embodiment 1, the sample that the back of quenching is obtained carries out X-ray diffraction studies, is found to be the BaRuO of monophasic cubic perovskite structure
3Crystal, crystalline quality is better.
Embodiment 3
1) under the normal pressure, utilize the solid state chemistry method to prepare monophasic 9R-BaRuO
3
Utilize solid state reaction, with the BaCO of 99.9% purity
3With mixed in molar ratio, the grinding with 1: 1 of the Ru powder of 99.9% purity, sintering under 900 ℃ condition is incubated 12 hours.Sintering 3 times under 1200 ℃ condition is incubated 24 hours at every turn then, just can obtain monophasic 9R-BaRuO
3
2) utilize high temperature and high pressure method to synthesize the BaRuO of monophasic cubic perovskite structure
3Crystal.
With the single-phase 9R-BaRuO that obtains under the normal pressure
3The sequin that is pressed into, preferred diameter is that 1.5mm, thickness are 2mm, and with goldleaf or platinum foil parcel, this sample is put into the tantalum well heater, carries out height in the high pressure assembly of packing into and is pressed into, the medium of using in the tantalum well heater is magnesium oxide and zirconium white.Sample synthesizes on the big press of six-eight types and carries out, and at room temperature slowly boosts to 20GPa earlier, restarts heating schedule and is heated to 900 ℃, is incubated 120 minutes then, is quenched to room temperature, release then (1GP,a=1 ten thousand normal atmosphere).
With embodiment 1, the sample that the back of quenching is obtained carries out X-ray diffraction studies, is found to be the BaRuO of monophasic cubic perovskite structure
3Crystal, crystalline quality is better.
It should be noted that; above in conjunction with the embodiments technical scheme of the present invention is had been described in detail; but those skilled in the art will find apparent that; on the technical solution of the present invention basis; can carry out variations and modifications to technical scheme of the present invention, but not break away from the generalized scope required for protection of claims of the present invention.