WO2012091198A1 - 프라세오디뮴이 도핑된 칼슘-망간계 열전 조성물 및 그 제조방법 - Google Patents
프라세오디뮴이 도핑된 칼슘-망간계 열전 조성물 및 그 제조방법 Download PDFInfo
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- WO2012091198A1 WO2012091198A1 PCT/KR2010/009463 KR2010009463W WO2012091198A1 WO 2012091198 A1 WO2012091198 A1 WO 2012091198A1 KR 2010009463 W KR2010009463 W KR 2010009463W WO 2012091198 A1 WO2012091198 A1 WO 2012091198A1
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- praseodymium
- manganese
- calcium
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- 239000000203 mixture Substances 0.000 title claims abstract description 65
- 229910052777 Praseodymium Inorganic materials 0.000 title claims abstract description 36
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 title claims abstract description 30
- UMRUNOIJZLCTGG-UHFFFAOYSA-N calcium;manganese Chemical compound [Ca+2].[Mn].[Mn].[Mn].[Mn] UMRUNOIJZLCTGG-UHFFFAOYSA-N 0.000 title claims abstract description 22
- 238000002360 preparation method Methods 0.000 title abstract description 4
- 238000001354 calcination Methods 0.000 claims abstract description 88
- 239000011575 calcium Substances 0.000 claims abstract description 49
- 239000011572 manganese Substances 0.000 claims abstract description 37
- 239000000463 material Substances 0.000 claims abstract description 31
- 238000005245 sintering Methods 0.000 claims abstract description 24
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 12
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 39
- 230000008569 process Effects 0.000 claims description 26
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 238000010298 pulverizing process Methods 0.000 claims description 2
- 229910052761 rare earth metal Inorganic materials 0.000 abstract description 8
- 230000000052 comparative effect Effects 0.000 abstract description 2
- 150000002500 ions Chemical class 0.000 description 47
- 239000012071 phase Substances 0.000 description 45
- 230000008859 change Effects 0.000 description 22
- 239000002019 doping agent Substances 0.000 description 12
- 229910052779 Neodymium Inorganic materials 0.000 description 8
- 229910052772 Samarium Inorganic materials 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 238000002441 X-ray diffraction Methods 0.000 description 7
- 230000008901 benefit Effects 0.000 description 7
- 239000013078 crystal Substances 0.000 description 7
- 239000007858 starting material Substances 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- -1 praseodymium ions Chemical class 0.000 description 6
- 239000000523 sample Substances 0.000 description 6
- 239000006104 solid solution Substances 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 229910000428 cobalt oxide Inorganic materials 0.000 description 3
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 description 3
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000005536 Jahn Teller effect Effects 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- 229910001424 calcium ion Inorganic materials 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 2
- 125000004430 oxygen atom Chemical group O* 0.000 description 2
- 150000002910 rare earth metals Chemical class 0.000 description 2
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 2
- 238000003746 solid phase reaction Methods 0.000 description 2
- 241000877463 Lanio Species 0.000 description 1
- 229910017493 Nd 2 O 3 Inorganic materials 0.000 description 1
- OXLRDKBGARCSLL-UHFFFAOYSA-N [Ca].[Co]=O Chemical compound [Ca].[Co]=O OXLRDKBGARCSLL-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000009770 conventional sintering Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 230000005923 long-lasting effect Effects 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 150000002697 manganese compounds Chemical class 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 229910002076 stabilized zirconia Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/80—Constructional details
- H10N10/85—Thermoelectric active materials
- H10N10/851—Thermoelectric active materials comprising inorganic compositions
- H10N10/855—Thermoelectric active materials comprising inorganic compositions comprising compounds containing boron, carbon, oxygen or nitrogen
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/016—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on manganites
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/01—Manufacture or treatment
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
- C04B2235/3208—Calcium oxide or oxide-forming salts thereof, e.g. lime
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3262—Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
- C04B2235/3265—Mn2O3
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- C04B2235/76—Crystal structural characteristics, e.g. symmetry
- C04B2235/768—Perovskite structure ABO3
Definitions
- the present invention relates to a calcium-manganese-based thermoelectric composition doped with praseodymium, and more particularly, to a calcium-manganese-based thermoelectric composition,
- Preparing a mixture by mixing praseodymium-doped calcium-manganese-based thermoelectric compositions and calcium-based materials, manganese-based materials, and praseodymium-based materials by doping praseodymium to the composition to replace a portion of calcium with praseodymium; Calcining the mixture a plurality of times, wherein each calcination temperature is increased as the number of calcinations increases; And sintering the mixture calcined a plurality of times.
- Praseodymium-doped calcium-manganese-based thermoelectric composition is provided.
- the formation of a single phase was relatively advantageous in the case of praseodymium doping, compared with the case of doping other rare earth elements presented as a comparative example, and thus the structural distortion of the perovskite structure was minimized, resulting in good thermoelectric properties. As a result, it was possible to implement the highest output argument.
- thermoelectric oxide has the advantage that it can be used for a long time in a high temperature environment and air.
- their constituents are abundant resources available everywhere on earth and have the advantage of having low toxicity compared to heavy metal compounds.
- thermoelectric oxide is a very promising material as an energy source, and has excellent performance especially in a high temperature environment.
- Terasaki has reported NaxCoO 2 as a thermoelectric oxide with high Seebeck coefficient (100 ⁇ V / K at 300K) and low resistance (0.2m ⁇ at 300K).
- Ca 3 Co 4 O 9 a calcium cobalt oxide, has also been reported to have high electrical conductivity and excellent Seebeck coefficient. From these results it can be evaluated that the thermoelectric performance of the thermoelectric oxide can be compared with the intermetallic compound.
- such a cobalt oxide system has a disadvantage in that it has an anisotropic crystal structure that interferes with thermoelectric properties, and thus requires separate handling in the process, and thus, a polycrystalline cobalt oxide system manufactured through a conventional sintering process is layered.
- a polycrystalline cobalt oxide system manufactured through a conventional sintering process is layered.
- the improvement of thermoelectric performance will be long lasting. Therefore, in order to improve thermoelectric performance, it must be made of polycrystalline having a more improved structure or reconstituted into a structure having a single phase.
- Perovskite structures as electronic ceramics have advantages in that they have an isotropic crystal structure and can easily control electrical properties.
- the first advantage is the isotropic crystal structure of perovskite, which does not require complex manufacturing processes such as new implementations of the improved structure to overcome anisotropy.
- the second advantage is that it is possible to easily control the electrical properties, it can be produced with a perovskite of a variety of structures by applying a variety of members having a variety of ion radius and valence to different types of perovskite.
- An ideal perovskite structure is an ABO 3 cubic structure. The ions at the A site have a relatively large ion radius, which is almost similar to the radius of the O 2- ions.
- ions at the B site have a relatively small ion radius.
- perovskite structures have been found, for example A 3+ B 3+ O 2 , A 2+ B 4+ O 3 , A 2+ B 3+ 1/2 B 5+ 1/2 O 3 Etc.
- the electrical conductivity of the oxide depends on the carrier concentration and the carrier mobility.
- these two elements can be controlled simultaneously, which is possible by using dopants.
- the valence is 4+ for all Mn ions. If some donors produce positive defects in the perovskite, the valence charge of Mn 4+ will change to Mn 3+ depending on the amount of donor. As a result, the valence mixed by Mn 3+ and Mn 4+ will increase the carrier concentration by Verwey's Verwey controlled ionic valence principle.
- Ca 1-x R x MnO 3 perovskite is implemented as an n-type semiconductor.
- this ABO 3 perovskite system it is possible to substitute dopant ions at the A site and the B site at the same time, thereby controlling the carrier concentration. It is also possible to control the mobility of the perovskite oxide by controlling the tolerance factor of the perovskite structure. In particular, adjusting the ion radius ratios of the A-site and B-site ions affects the carrier mobility of the perovskite structure.
- the perovskite structure has a higher phase stability than other electronic ceramics.
- the research history of perovskite has been around for 60 years. Therefore, not only a considerable amount of data related to the phase stability of perovskite is accumulated, but various means exist that can enhance their electrical properties.
- research on the thermoelectric performance of this kind of perovskite structure is still in its infancy.
- three rare earth dopants such as praseodymium ions (Pr 3+ , praseodimium), neodymium ions (Nd 3+ , neodimium), and samarium ions (Sm 3+ , samarium) have 0.01 or 0.05 doping amount at Ca ion sites.
- the carrier concentration was adjusted by varying the amount to 0.1 mol%.
- the rare earth ions were selected to have a similar ion radius to Ca 2+ ions.
- the effects of doping on the formation properties, mobility and carrier concentration of single phase in Ca 1-x R x MnO 3 perovskite were investigated.
- the thermoelectric performance of Ca 1-x R x MnO 3 perovskite doped with rare earth ions Pr 3+ , Nd 3+ and Sm 3+ was investigated.
- the present invention has been made to solve the problems described above, the present invention in selecting a dopant for replacing the calcium of the calcium-manganese-based thermoelectric composition, in particular by selecting praseodymium to minimize the structural distortion of the thermal composition It is an object of the present invention to maximize output factors and to improve thermoelectric properties.
- the present invention is to introduce a plurality of calcination process in the manufacture of the thermoelectric, to control the calcination temperature and the calcination temperature interval, calcination time, the number of calcination, etc. It is another object of the present invention to be able to produce a thermoelectric having excellent physical properties by interlocking.
- thermoelectric properties of the thermoelectric composition according to the present invention praseodymium was selected as a dopant, and further improvement of the thermoelectric properties by praseodymium is possible by introducing a plurality of calcination processes in which a series of variables are controlled. Therefore, the selection of the dopant and the series of calcination processes have an organic relationship with each other.
- the present invention comprises the steps of preparing a mixture by mixing calcium-based materials, manganese-based materials, praseodymium-based materials to achieve the object as described above; Calcining the mixture a plurality of times, wherein each calcination temperature is increased as the number of calcinations increases; And sintering the mixture calcined a plurality of times.
- Praseodymium-doped calcium-manganese-based thermoelectric composition is provided.
- the calcium-based material is CaCO 3 (99.99%, high purity chemistry)
- manganese-based material is preferably Mn 2 O 3
- praseodymium-based material is preferably Mn 2 O 3 .
- each calcination temperature is increased as the number of calcination increases, the calcination is carried out at least three times in the temperature range of 900 ⁇ 1200 °C, the calcination temperature after the preceding calcination temperature To be higher, the subsequent calcination temperature is at least 50 °C higher than the preceding calcination temperature, the calcination of the last step in the plural number of calcination process is preferably carried out in the temperature range of more than 1100 °C 1200 °C.
- each calcining temperature is increased as the number of calcining increases, it is preferable to further include the step of grinding the calcined mixture after each calcining.
- the sintering temperature is preferably to be carried out in the range of more than 1200 °C 1300 °C.
- the present invention provides a calcium-manganese-based thermoelectric composition doped with praseodymium, which is prepared by the above method, and doped praseodymium to replace a portion of calcium with praseodymium.
- x is preferably in the range of 0 ⁇ x ⁇ 0.1.
- the praseodymium-doped calcium-manganese-based thermoelectric composition exhibits a larger output factor than that of the neodymium or samarium-doped composition, and realizes the thermal composition as a solid solution in a single phase while minimizing structural distortion. Since the thermoelectric properties of the thermoelectric composition can be optimized, the effect of making the thermoelectric composition practically meaningful is expected.
- thermoelectric body by calcining and sintering the thermoelectric composition
- the number of times, the calcination temperature, the temperature interval between each calcination process, the upper and lower limits of the calcination temperature, and the like are controlled.
- the overall process variable by interlocking it is expected that the effect of producing a thermoelectric having optimal properties.
- 1 is an X-ray analysis of Ca 0.9 Sm 0.1 MnO 3 sample according to an embodiment of the present invention, (a) the first calcination for 15 hours at 900 °C, (b) 1000 °C after the first calcination The second calcination for 15 hours at, (c) the third calcination for 15 hours at 1100 ° C. after the second calcination, (d) the fourth calcination for 15 hours at 1200 ° C. after the third calcination, (e ) Shows the sintered at 1300 °C for 15 hours after the fourth calcination.
- thermoelectric property measured in the temperature range of 333K to 1132K of Ca 0.9 Sm 0.1 MnO 3 sample according to an embodiment of the present invention (a) change in electrical conductivity according to the change in the doping amount, (b) doping The change of Seebeck coefficient with each change is shown.
- Figure 4 shows the change of the output factor according to the change in the doping amount in the temperature range of 333K to 1132K of the Ca 1-x Nd x MnO 3 sample according to an embodiment of the present invention.
- the thermoelectric properties change with the change of the radius, (a) the electrical conductivity and the Seebeck coefficient at 1080K, and (b) the output parameters at 877K to 1132K.
- Perovskite oxides have an isotropic crystal structure and are easy to control electrical properties, making them a promising material in the field of thermoelectric materials.
- polycrystalline Ca 1-x R x MnO 3 (R: Pr, Nd, Sm) compositions were prepared by a solid phase reaction method.
- three different rare earth dopants were substituted in Ca ion sites by varying the amount of addition thereof, and as described below, the best thermoelectric properties were obtained in the case of Pr.
- electrical conductivity, Seebeck coefficient and power factor were measured and phase analysis was performed. The effect of ion radius change and the amount of doping on the carrier concentration were investigated.
- the material is only one example selected as a starting material, and other possible calcium-based materials, manganese-based materials, neodymium-based materials, samarium-based materials, and praseodymium-based materials are all possible.
- thermoelectric composition In preparing the thermoelectric composition according to the present invention, the lower the corresponding calcination temperature is, the better. This is because if the calcination temperature is high, much of the starting material for the preparation of the thermoelectric composition is volatilized before it is synthesized into the desired phase, so that the composition ratio may deviate from the previously designed composition. In addition, when the calcining temperature is high, when sintering it after synthesis, the sintering density may be decreased. Because after calcination to pulverize again to make fine powder, the specific surface area of the powder is increased, so that the sintering driving force is increased to obtain a dense density after the final sintering.
- the calcination temperature of the starting material for preparing the thermoelectric composition was performed in a temperature range of about 900 °C to 1200 °C.
- the upper limit of the calcination temperature was set at 1200 ° C. in order to avoid the problem of pulverization due to high temperature calcination.
- the higher the calcination temperature the more advantageous it is for the generation of a single phase.
- the lower limit of the calcination temperature is 900 °C, since the melting point of the starting material Mn 2 O 3 is about 940 °C, it is advantageous to produce a single phase, but as high as possible within the range not exceeding the melting point of Mn 2 O 3 To do this.
- calcination is first started at a temperature exceeding the melting point of the starting material Mn 2 O 3 , there is a problem that volatilization occurs. Therefore, a temperature below the above temperature will be meaningless with respect to the problem of generating a single phase.
- thermoelectric as close to a single phase as possible from the calcination process. That is, the upper limit of the calcining temperature is set to 1200 ° C to facilitate the grinding process, which is a previous step for sintering while the thermoelectric composition according to the present invention implements a single phase. That is, when calcining in a temperature range above 1200 ° C., in particular about 1300 ° C. as in the present invention, it is not difficult to regrind the calcined thermoelectric composition.
- the sintering is carried out simultaneously at a temperature exceeding 1200 ° C., which can realize a single phase, but the calcination temperature is 1100 ° C. in consideration of the grinding for sintering while being as close to the single phase as possible. Exceeded, but the upper limit to 1200 °C.
- the above calcined temperature range has its critical significance at the upper and lower limits of the above range.
- the calcination temperature interval should be at least 50 ° C.
- the calcination process is set in a step-up manner.
- the second phase remaining in trace amount after the calcination process was to be removed during the sintering process, at which time the sintering temperature is more than 1200 °C 1300 °C or less.
- the sintering process should be as close to the single phase as possible, but the second phase that could not be removed can be removed during the sintering process. Therefore, the sintering density and the realization of the single phase can be achieved through this series of calcination and sintering processes. It was.
- thermoelectric obtained from the organic interlocking process is characterized by the present invention in terms of sintering density, formation of a single phase, and the like. .
- ⁇ V is the thermoelectric power according to the temperature change ⁇ T.
- YbMnO 3 perop with A site ions with small radius has a function myeonjeong (rhombohedral) structure.
- the difference in ion radius between A site ions causes a difference in crystal structure.
- This other structure prevents the formation of a solid solution of a single phase.
- substituted dopants tend to produce new secondary phases, especially in ordered perovskite structures.
- the ions of the A site large and small alternately occupy the A site to produce an A 0.5 A 0.5 BO 3 perovskite structure.
- r A , r B , r O means the ion radius of each ion.
- the ion radius in the crystal structure has various values depending on the change in the coordination number and the charge of the ions.
- the t value ranges from 0.75 to 1.1.
- the t value converges to one.
- the octahedron realized by the oxygen atoms surrounding Mn is located exactly at the vertices of the cubic perovskite structure.
- the octahedron is not distorted.
- the shape distortion gradually increases.
- the reduction in r A intensifies the distortion of the tetragonal phase.
- the octahedron caused by oxygen is further distorted to produce a twisted structure similar to a zigzag chain.
- the tolerance factors are 0.996, 0.995, and 0.994 for Pr 3+ (1.30 °, 12 th coordinated), Nd 3+ (1.27 °, 12 th coordinated), and Sm 3+ (1.24 °, 12 th coordinated), respectively.
- the tolerance factors are 0.996, 0.995, and 0.994 for Pr 3+ (1.30 °, 12 th coordinated), Nd 3+ (1.27 °, 12 th coordinated), and Sm 3+ (1.24 °, 12 th coordinated), respectively.
- the coordination numbers of A site ions, B site ions, and O ions (1.40 ⁇ , 6 th coordinated) for calculating tolerance factor values were set to 12, 6, and 6.
- the tolerance factor was calculated by introducing the ion radius of Shannon.
- I difficult to achieve a single phase of solid solution than in other cases with more ion of large ionic radius in the case of Sm 3+ doping it results that the ionic radius of Sm 3+ ion small Sm 3+ This is because the tolerance factor for is low.
- Mn 4+ (0.53 ⁇ , 6 th coordinated) changes to Mn 3+ (0.645 ⁇ , 6 th coordinated) in proportion to the donor dose.
- the change in charge from Mn 4+ to Mn 3+ affects two aspects of the CaMnO 3 perovskite structure. The first is an increase in the ion radius of Mn.
- the tolerance factor in such donor-doped CaMnO 3 systems can be calculated after the average radius of Mn ions has taken into account the change in charge due to doping.
- the second effect is Jahn-Teller distortion.
- Structural distortion of CaMnO 3 perovskite is not only associated with a decrease in tolerance factor but also associated with the presence of Jahn-Teller type Mn 3+ cations at site B with octahedral coordination. These cations increase the strain of anisotropy, which leads to a change in symmetry.
- the electron arrangement in e g electronic systems such as Mn 3+ manganese compounds is t 2 g 3 , e g1 .
- e g electrons form an orbital function.
- the Jahn-Teller effect prevents the degeneracy of the e g orbital function by causing a large deformation of the MnO 6 octahedron.
- the distortion of the structure is accelerated as the doping amount of the donor increases. That is, five d orbitals of an atom are split into three t 2 g electron orbits and eg two electron orbits when forming a chemical bond with other atoms.
- Figure 3a is a graph showing that the electrical conductivity is increased in proportion to the increase in the doping amount in the Ca 1-x Nd x MnO 3 system. This proves that the electron concentration increases due to the change in charge from Mn 4+ to Mn 3+ according to Verwey's controlled ion charge theory.
- 3B is a graph showing the reduction of Seebeck coefficient proportional to the amount of doping in Ca 1-x Nd x MnO 3 system.
- the Seebeck coefficient tends to be inversely proportional to the electrical conductivity in thermoelectric materials. Therefore, it is possible to derive the fact that the electron concentration increases due to the charge change according to Verwey's controlled ion charge theory from the reduction of the Seebeck coefficient in the present invention.
- the output factor value is expressed as S 2 ⁇ ⁇ , and this output factor increases with increasing carrier concentration with increasing electrical conductivity. Therefore, in the high carrier concentration region, the output factor value decreases with increasing carrier concentration with decreasing Seebeck coefficient. Therefore, the output factor value usually has a maximum value in the middle region of the carrier concentration.
- the output factor value increased with increasing doping amount over the entire range. This result confirms that the carrier concentration, more precisely, the doping amount has not been maximized yet. Therefore, the output factor value is likely to be higher depending on the amount of doping added.
- FIG. 5A The influence on the electrical conductivity according to the change of the tolerance factor is shown in FIG. 5A.
- a dopant having a smaller amount of dopant than the host ion Ca 2+ is added, it is difficult to form a solid solution of a single phase, which is Mn ion. This is due to the distortion of the oxygen octahedron surrounding it.
- doping large ions at the A site effectively increases the electrical conductivity, especially in the case of a large tolerance factor.
- the electrical conductivity of Pr doped specimens was higher than in other cases.
- Sm doping showed lower electrical conductivity than other specimens.
- This value can be compared with the value of Ca 3 Co 4 O 9 , which is evaluated as the most promising thermoelectric oxide.
- FIG. 5A despite the high electrical conductivity, the reason for having the highest Seebeck coefficient in the case of Pr doping is not yet clear.
- Pr ions have a complex electronic structure, and therefore there is a possibility of a valence change from Pr 3+ to Pr 4+ in the oxide, for example, Pr of such a complex electronic structure Improves disorder and Seebeck coefficient
- the thermal conductivity of the doped CaMnO 3 system was 1.7 to 1.5 W / mK at a temperature of 1100 K.
- the dimensionless figure of merit (ZT) can be calculated to have a value of greater than about 0.28 at 1132 K, which can be compared with Ca 3 Co 4 O 9 , which is evaluated as the most promising thermoelectric oxide.
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Abstract
Description
Claims (8)
- 칼슘계 물질, 망간계 물질, 프라세오디뮴계 물질을 혼합하여 혼합물을 제조하는 단계;상기 혼합물을 복수횟수로 하소하되, 각 하소온도는 하소횟수가 증가함에 따라 점증하도록 하는 단계; 및상기 복수횟수로 하소된 혼합물을 소결하는 단계;를 포함하는 것을 특징으로 하는 프라세오디뮴이 도핑된 칼슘-망간계 열전 조성물의 제조방법.
- 제 1 항에 있어서,상기 칼슘계 물질은 CaCO3(99.99%, 고순도 화학), 망간계 물질은 Mn2O3, 프라세오디뮴계 물질은 Mn2O3 인 것을 특징으로 하는 프라세오디뮴이 도핑된 칼슘-망간계 열전 조성물의 제조방법.
- 제 1 항에 있어서,상기 혼합물을 복수횟수로 하소하되, 각 하소온도는 하소횟수가 증가함에 따라 점증하도록 하는 단계에서,상기 하소는 900 ~ 1200℃의 온도범위에서 적어도 3회 수행되며, 선행 하소온도보다 후행 하소온도가 더 높도록 하되, 후행 하소온도는 선행 하소온도에 비하여 적어도 50℃ 높고, 상기 복수횟수의 하소과정에서 마지막 단계의 하소과정은 1100℃ 초과 1200℃ 이하의 온도범위에서 수행되는 것을 특징으로 하는 프라세오디뮴이 도핑된 칼슘-망간계 열전 조성물의 제조방법.
- 제 1 항에 있어서,상기 혼합물을 복수횟수로 하소하되, 각 하소온도는 하소횟수가 증가함에 따라 점증하도록 하는 단계에서,상기 각 하소 후에는 하소된 혼합물을 분쇄하는 단계가 더 포함되도록 하는 것을 특징으로 하는 프라세오디뮴이 도핑된 칼슘-망간계 열전 조성물의 제조방법.
- 제 1 항에 있어서,상기 복수횟수로 하소된 혼합물을 소결하는 단계에서,상기 소결온도는 1200℃ 초과 1300℃ 이하의 범위에서 수행되는 것을 특징으로 하는 프라세오디뮴이 도핑된 칼슘-망간계 열전 조성물의 제조방법.
- 제 1 항의 방법에 의해 제조되며, 프라세오디뮴을 도핑하여 칼슘의 일부를 프라세오디뮴으로 치환하는 것을 특징으로 하는 프라세오디뮴이 도핑된 칼슘-망간계 열전 조성물.
- 제 6 항에 있어서,상기 프라세오디뮴이 도핑된 칼슘-망간계 열전조성물을 Ca1-xPrxMnO3로 표현하였을 때, 상기 x는 0<x≤0.1의 범위인 것을 특징으로 하는 프라세오디뮴이 도핑된 칼슘-망간계 열전 조성물.
- 제 7 항에 있어서,상기 프라세오디뮴이 치환된 열전 조성물은 x=0.1 및 1123K의 온도에서 3.98×10-4W/mK2의 최대 출력인자 값을 갖는 것을 특징으로 하는 프라세오디뮴이 도핑된 칼슘-망간계 열전 조성물.
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JP2013547280A JP5647742B2 (ja) | 2010-12-29 | 2010-12-29 | プラセオジミウムがドーピングされたカルシウム−マンガン系熱電組成物及びその製造方法 |
PCT/KR2010/009463 WO2012091198A1 (ko) | 2010-12-29 | 2010-12-29 | 프라세오디뮴이 도핑된 칼슘-망간계 열전 조성물 및 그 제조방법 |
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KR20020028842A (ko) * | 2000-10-11 | 2002-04-17 | 무라타 야스타카 | 부온도계수의 저항을 갖는 반도체 세라믹 및 부온도계수서미스터 |
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JP2007158318A (ja) * | 2005-12-07 | 2007-06-21 | Sharp Corp | 有機金属化学気相成長法によるPrMnO3/CaMnO3超格子構造を有するPrxCa1−xMnO3薄膜の形成方法 |
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CN116082039A (zh) * | 2022-12-22 | 2023-05-09 | 哈尔滨工业大学 | 一种不等价离子掺杂的高发射率低热导功能复合陶瓷或涂层制备的方法 |
CN116082039B (zh) * | 2022-12-22 | 2023-10-20 | 哈尔滨工业大学 | 一种不等价离子掺杂的高发射率低热导功能复合陶瓷或涂层制备的方法 |
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