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Transition metal compounds have become a research hotspot in the field of inorganic solid chemistry because of their unique force, heat, light, electrical, and magnetic properties and the numerous synergistic effects they exhibit. He was chaired by Meng Jian, a researcher at the State Key Laboratory of Rare Earth Resources Utilization of Changchun Institute of Applied Chemistry, and the key project of the National Natural Science Foundation of China was undertaken by a research team composed of Prof. Xing Xianran of Beijing University of Science and Technology and Prof. Wu Zhijian and Researcher of Cao Xueqiang of Changchun Yinghua Institute. "Studies on the synthesis and special properties of transition metal compounds" were recently identified by experts from the National Natural Science Foundation of China. Experts believe that the research results obtained by this project have important academic significance and wide practical application value, and have reached the advanced level of international similar research.
First, according to the structure of the transition metal compounds and the relationship between the bonding and the electrical and magnetic properties of the chemical bonds, the structural design of the compounds was carried out and the structure-activity relationship theory simulation was carried out in an effort to clarify the relationship between the crystal structure and the physical properties of the compounds.
The electrical and magnetic properties of YBaMn2O5 were studied. It was found that the magnetic coupling of this type of compound changes from G antiferromagnetic to A antiferromagnetic with the change of Mn-O-Mn angle. The theoretical calculation results support both The experimental results also verified Goodenough's magnetic coupling theory.
The thermodynamic stability of a new type of compound CaCu3Fe4O12 was successfully predicted, and it has a ferrimagnetic semimetal structure, and it is very likely to become a new type of spintronic material. Shortly after the publication of our article, the research team of Professor Y. Shimakawa of Kyoto University in Japan succeeded in synthesizing the compound, which fully proved the reliability and forward-lookingness of theoretical research.
Secondly, starting from the structural design, the relationship between structural distortion and physical properties of compounds was studied. The mechanism of ion and electron conduction in compounds was proposed. An oxygen ion conductor with good performance under low and middle temperatures was designed and synthesized.
A complete set of electrical property test system was designed and developed by ourselves, which can automatically control the conductivity and Seebeck coefficient of the measured material. The test range of temperature and oxygen partial pressure is wide (1~10-17Pa, room temperature ~1000°C), can simulate the atmosphere of any oxygen partial pressure condition; design and synthesis of new solid oxide electrolyte La2Mo2O9, La3MMo2O12 and double perovskite structure oxidation It was found that its oxygen ion conductivity in the middle temperature region is higher than that of the traditional fluorite and perovskite solid electrolyte. It is found that the d-orbital interaction of Mo ions can form a direct overlap of the t2g orbital. It can be considered that the electrons of the Mo ion transition to the neighboring Mo ion through the sigma bond or the π bond, and then the electron conduction occurs. Further improved the ion and electron conduction mechanism.
Third, a series of lead-based titanate ceramics were studied, and the structural refinement of the full-spectrum fitting of the compounds was performed by the Rietveld method, and the order of the B-sites in the compounds was resolved by an ordered-disordered model. The order problem discovered that the doping of transition metal ions can well regulate the thermal expansion properties of the compound and found a new material with near zero swelling.
The lead-based titanate ceramics (1-xy)PbTiO3-xBiFeO3-yBi(Ti1/2Zn1/2)O3 were studied by design synthesis and structural distortion methods. Their structure was refined by Rietveld. The order-disorder model solves the order-disorder problem at the B site; a PbTiO3-0.1BiFeO3-0.3Bi(Zn1/2Fe1/2)O3-based compound with zero swell characteristics was observed at -140 to 700°C.
The synthesis, crystal structure, and thermal expansion of rare earth-doped lead titanate series compounds, the corresponding solid solution limits, the non-stoichiometry of the compounds, the thermodynamic stability of the solid solution compounds, and the solid solution compounds (nanoparticles) have been studied. ) The relationship between morphology and solid solubility, found negative thermal expansion material solid electrolyte Zr1-xYbxW2O8, at 300-700 °C for oxygen ion conductor; increased Y add impurity to improve the vacancy concentration, improve ionic conductivity. And a negative thermal expansion composite ZrW2O8/Al2O3 ceramic with adjustable thermal expansion coefficient and good mechanical properties of ceramics was prepared. For the first time, the negative thermal expansion characteristics of lead-based titanates have been enhanced, and it has been found that they can be adjusted to (nearly) zero-expansion TEC materials.
The above-mentioned research results have important academic significance and wide practical application value, reaching the advanced level of international similar research.
During the implementation of this project, Appl. Phys. Lett., Phys.Rev.B, Chem. Mater., Inorg.Chem., Cryst.Growth & Design., Euro. J. Inorg. Chem., J.Phys. There are 110 academic papers published by Chem.B, J.Chem.Phys., J.Appl.Phys. and other important publications at home and abroad, of which 101 are published abroad, 1 monograph has been published, and 18 national invention patents have been applied, among which one is authorized. Nine of them, while cultivating a group of young academic leaders, one of whom was funded by the “Hundred Talents Program†of the Chinese Academy of Sciences, and one person was named as the distinguished professor of Yangtze River Scholarship of the Ministry of Education.
First, according to the structure of the transition metal compounds and the relationship between the bonding and the electrical and magnetic properties of the chemical bonds, the structural design of the compounds was carried out and the structure-activity relationship theory simulation was carried out in an effort to clarify the relationship between the crystal structure and the physical properties of the compounds.
The electrical and magnetic properties of YBaMn2O5 were studied. It was found that the magnetic coupling of this type of compound changes from G antiferromagnetic to A antiferromagnetic with the change of Mn-O-Mn angle. The theoretical calculation results support both The experimental results also verified Goodenough's magnetic coupling theory.
The thermodynamic stability of a new type of compound CaCu3Fe4O12 was successfully predicted, and it has a ferrimagnetic semimetal structure, and it is very likely to become a new type of spintronic material. Shortly after the publication of our article, the research team of Professor Y. Shimakawa of Kyoto University in Japan succeeded in synthesizing the compound, which fully proved the reliability and forward-lookingness of theoretical research.
Secondly, starting from the structural design, the relationship between structural distortion and physical properties of compounds was studied. The mechanism of ion and electron conduction in compounds was proposed. An oxygen ion conductor with good performance under low and middle temperatures was designed and synthesized.
A complete set of electrical property test system was designed and developed by ourselves, which can automatically control the conductivity and Seebeck coefficient of the measured material. The test range of temperature and oxygen partial pressure is wide (1~10-17Pa, room temperature ~1000°C), can simulate the atmosphere of any oxygen partial pressure condition; design and synthesis of new solid oxide electrolyte La2Mo2O9, La3MMo2O12 and double perovskite structure oxidation It was found that its oxygen ion conductivity in the middle temperature region is higher than that of the traditional fluorite and perovskite solid electrolyte. It is found that the d-orbital interaction of Mo ions can form a direct overlap of the t2g orbital. It can be considered that the electrons of the Mo ion transition to the neighboring Mo ion through the sigma bond or the π bond, and then the electron conduction occurs. Further improved the ion and electron conduction mechanism.
Third, a series of lead-based titanate ceramics were studied, and the structural refinement of the full-spectrum fitting of the compounds was performed by the Rietveld method, and the order of the B-sites in the compounds was resolved by an ordered-disordered model. The order problem discovered that the doping of transition metal ions can well regulate the thermal expansion properties of the compound and found a new material with near zero swelling.
The lead-based titanate ceramics (1-xy)PbTiO3-xBiFeO3-yBi(Ti1/2Zn1/2)O3 were studied by design synthesis and structural distortion methods. Their structure was refined by Rietveld. The order-disorder model solves the order-disorder problem at the B site; a PbTiO3-0.1BiFeO3-0.3Bi(Zn1/2Fe1/2)O3-based compound with zero swell characteristics was observed at -140 to 700°C.
The synthesis, crystal structure, and thermal expansion of rare earth-doped lead titanate series compounds, the corresponding solid solution limits, the non-stoichiometry of the compounds, the thermodynamic stability of the solid solution compounds, and the solid solution compounds (nanoparticles) have been studied. ) The relationship between morphology and solid solubility, found negative thermal expansion material solid electrolyte Zr1-xYbxW2O8, at 300-700 °C for oxygen ion conductor; increased Y add impurity to improve the vacancy concentration, improve ionic conductivity. And a negative thermal expansion composite ZrW2O8/Al2O3 ceramic with adjustable thermal expansion coefficient and good mechanical properties of ceramics was prepared. For the first time, the negative thermal expansion characteristics of lead-based titanates have been enhanced, and it has been found that they can be adjusted to (nearly) zero-expansion TEC materials.
The above-mentioned research results have important academic significance and wide practical application value, reaching the advanced level of international similar research.
During the implementation of this project, Appl. Phys. Lett., Phys.Rev.B, Chem. Mater., Inorg.Chem., Cryst.Growth & Design., Euro. J. Inorg. Chem., J.Phys. There are 110 academic papers published by Chem.B, J.Chem.Phys., J.Appl.Phys. and other important publications at home and abroad, of which 101 are published abroad, 1 monograph has been published, and 18 national invention patents have been applied, among which one is authorized. Nine of them, while cultivating a group of young academic leaders, one of whom was funded by the “Hundred Talents Program†of the Chinese Academy of Sciences, and one person was named as the distinguished professor of Yangtze River Scholarship of the Ministry of Education.
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