In 1950s, Xu Guangxian put forward the theory of complex equilibrium adsorption. In 1960s, he improved and proposed several methods to determine the extraction constant. In 1970s, the optimal design scheme of cascade extraction was put forward, and a new theory of cascade extraction was established. In 1980s, a new definition of valence and its quantum chemistry were put forward, and a series of tetranuclear dioxygen rare earth complexes with special structures and properties were synthesized for the first time. He found that the rare earth solvent extraction system has the basic law of "constant mixed extraction ratio", and put forward a cascade extraction theory suitable for rare earth solvent extraction and separation, which can be directly applied to production practice, guide the comprehensive innovation of rare earth separation technology, and promote China's leap from a big country with rare earth resources to a big country with high purity rare earth. 197 1 End, Xu Guangxian returned to work in the Department of Chemistry of Peking University. At that time, the chemistry department was engaged in the separation and purification of rare earth elements. He thinks that the extraction method is promising for the separation and purification of rare earth, so he actively participates in this work, and uses the achievements and accumulated experience in the basic research of complex equilibrium and extraction chemistry in the past to make a breakthrough improvement on the extraction and separation process of rare earth. The separation of praseodymium and neodymium is a difficult point in the separation of rare earth elements, and it was an urgent military task at that time. By selecting extractant and complexing agent, he prepared quaternary ammonium salt -DTPA "push-pull" system, which increased the separation coefficient of Pr-Nd from 1.4- 1.5 in general extraction system to above 4, which was the highest in the world at that time. However, this system is difficult to be directly used in industrial production. There was a patent report in the United States that the push-pull system was used to extract and separate rare earths, but it was never used in actual production because the cascade extraction process could not be realized. At that time, the internationally popular cascade extraction theory was put forward by L. Alders. Xu Guangxian carefully analyzed the movement of complex equilibrium in the cascade extraction process, and found that the basic assumption of aldous's cascade extraction theory: "the extraction ratio is constant in the cascade extraction process" is not valid in the cascade extraction process of rare earth push-pull system. So he carefully designed a set of chemical operation flow, and deduced a set of corresponding theoretical formulas of cascade extraction. On this basis, he designed a new process of reflux cascade extraction.
From September 65438 to September 0974, he personally went to Baotou Rare Earth Plant No.3 to participate in the industrial scale test of this new technology for separating Baotou light rare earth, which was successful, thus realizing the industrial production of high-efficiency extraction and separation of rare earth by push-pull system for the first time in the world. On the basis of these works, he successively put forward the design principles and methods that can be widely used in the optimization process design of rare earth cascade extraction separation process, the extreme value formula, and the design principles and methods of fractional extraction three-outlet process, and established mathematical models and calculation programs such as cascade extraction dynamic process and reflux start-up mode. These principles and methods are used in practical production, which greatly simplifies the process of designing process parameters and reduces the consumption of chemical experiments. Especially for factories with different raw materials and equipment, so it is widely used. He, Li, and others have successfully studied the "one-step amplification" technology in the process of rare earth extraction and separation. On the basis of in-depth study and revealing the basic law of cascade extraction process, computer simulation is used to replace the traditional small-scale cascade extraction test, which realizes one-step amplification to industrial production without small-scale test and enlarged test, greatly shortens the cycle from new process design to production, and makes China's rare earth separation technology reach the international advanced level. Xu Guangxian, the pioneer of solution complex chemistry research in China, is very sensitive to the growing point of the frontier of discipline development, and can grasp the new trend of international academic development and select promising research fields and topics in time in combination with the actual situation in China. 195 1 continued to engage in quantum chemistry research at the beginning of returning to China. At that time, the international research on the equilibrium of complex in solution was in the ascendant, and he keenly felt that it would develop into an important branch of inorganic chemistry, and China also had the conditions to do this work. So he quickly seized this opportunity and took the lead in studying the physical chemistry of the complexation process in solution in China. The first is to determine the equilibrium constant of the complex in solution. By improving the instruments and equipment, he improved the measurement accuracy and the processing method of experimental data, so he can get more information from the measurement results. In addition, with the new experimental data processing method, he can get more accurate results and give more accurate graded complex constants for weakly complex systems. His work in the determination of complex equilibrium constants quickly reached the international advanced level, which also promoted the development of related research work in China. According to the similarity between complex equilibrium and adsorption equilibrium, he put forward complex equilibrium adsorption theory, which can simply describe the process of weak complex equilibrium in solution. The achievements of this period are of great help to his later successful research on nuclear fuel extraction chemistry and rare earth chemistry. Since 1970s, he has noticed his interest in bioinorganic chemistry and immediately realized the significance of studying biomolecule ligand complexes. He encouraged, supported and guided the comrades in the scientific research group to actively carry out this work, such as studying the formation mechanism of gallstones, the dyeing mechanism of rare earth wool, and the complexing effect of anticancer drug molecules on metal ions. Since 1980s, he has directed his assistants and students to do a lot of work in the synthesis, structural determination and spectral study of solid complexes, especially in the polynuclear and heteronuclear complexes of rare earth elements. For example, a series of tetranuclear rare earth dioxygen complexes with special structures and properties were synthesized for the first time in the world, which attracted the attention of peers. Exploring the relationship between the structure and properties of materials Since the early 1970s, the chemistry of organometallic compounds and clusters has developed rapidly, and a large number of new compounds have been synthesized, and the research on their structures and properties has also developed. Therefore, the structural laws of organometallic compounds and clusters have become a concern of many scholars. By summarizing a lot of experimental data and existing theories, Xu Guangxian put forward a more general structural rule, which is also applicable to organometallic compounds, clusters and general molecules, and named it (nxcπ) format. Related to this, a new definition of valence is also proposed. Using the structural law of (nxcπ), we can estimate the molecular stability according to the molecular structural formula, and then predict the possible new compounds. This structural rule and definition have been tested by a large number of experimental results and quantum chemical calculation results, showing its correctness and wide applicability.
Since the late 1970s, Xu Guangxian has been studying the quantum chemistry of rare earths and the structural regularity of rare earth compounds. On the basis of establishing a method and calculation program suitable for studying the electronic structure of rare earth elements, he systematically calculated the quantum chemistry of different types of rare earth compounds, and combined with the structural rules of (nxcπ) and the new definition of valence of * * * *, analyzed their bonding situation. The results show that rare earth compounds are not always ionic, and there are ionic bonds in organometallic compounds, while there are ionic bonds in many inorganic compounds. The valence bonds of * * * are mainly generated by its 5d orbitals, and the 4f orbitals have a relatively small contribution, so the clusters of rare earth and organometallic compounds obey the generalized 18-electron law. Xu Guangxian * * * has published more than 560 periodical papers, which have been cited by others for more than 2,200 times, and published textbooks and monographs 10, including many important textbooks such as Material Structure and Quantum Chemistry. Since the publication of 1959, Material Structure has been revised and reprinted for more than 200,000 copies, which is an important teaching reference book in the field of chemistry. Lectures on Material Structure (edited by Xu Guangxian, Summer University Teaching and Research Symposium, 1954).
"(Xu Guangxian, Higher Education Press,195965438+February).
Material structure (by Xu Guangxian, People's Education Press, 196 1)
A Concise Course of Material Structure (edited by Xu Guangxian, Higher Education Press 1965)
Quantum Chemistry: Basic Principles and Ab initio Method (Xu Guangxian/Li Lemin/Wang Demin, Science Press, 1980).
Principles of Extraction Chemistry (Xu Guangxian, Shanghai Science and Technology Press, 1984).
New Frontier of Rare Earth Science and Application (Xu Guangxian, Science Press, 1985 1).
Material structure (edited by Xu Guangxian/Wang Xiangyun, Higher Education Press, 1987).
Solvent extraction of rare earths (by Xu Guangxian, Science Press, 1987).
Material structure (Xu Guangxian/Wang Xiangyun, Higher Education Press, 1987).
Selected Papers of Professor Xu Guangxian (Xu Guangxian, Rare Earth Chemistry Research Center, Department of Chemistry, Peking University, 1990).
Selected Papers of Xu Guangxian (Xu Guangxian, Beijing University of Technology Press, 1995).
1955- 1956 Peking University scientific seminar, papers of chemistry branch (by Xu Guangxian, Peking University Press, 1995).
Rare Earth (edited by Xu Guangxian, Metallurgical Industry Press, 1995)
Magical Land: Basic Research on Rare Earth Science (edited by Xu Guangxian, Hunan Science and Technology Press, 1995).
Xu Guangxian's Collected Works (Xu Guangxian, Peking University Publishing House, 2000) The quantum chemical theory of optical rotation (195 1 year).
Exploration beyond the frontier of chemistry-a new garden intersecting with information science (May 2005) attaches importance to teaching. Xu Guangxian attached importance to teaching, and believed that students must firmly grasp the basic theories and knowledge of science, so as to lay a solid foundation for devoting themselves to the scientific and technological undertakings of the motherland in the future.
195 1 taught physical chemistry in the department of chemistry in Peking University, and offered quantum chemistry to graduate students in the department of chemistry in yenching university. After the adjustment of the department, a new course of material structure was opened in Peking University. He was the lecturer of 1954 summer advanced course of material structure.
1957, the state asked Peking University to train atomic energy science and technology personnel quickly. Xu Guangxian was not familiar with atomic energy chemistry at that time, but after being appointed as one of the heads of this work, he prepared lessons day and night. Two months later, he began to teach courses such as radiochemistry and introduction to nuclear physics. He attaches great importance to let young teachers and graduate students grasp the latest achievements of the discipline in time and stand at the forefront of the development of the discipline. In the late 1950s, the application of coordination field theory in inorganic chemistry expanded rapidly in the world, and the research of extraction chemistry just started. He provided courses on coordination field theory and extraction mechanism to young teachers and graduate students in technical physics department in time. After the downfall of the Gang of Four, China attached great importance to basic research. At that time, after more than ten years of rapid development, quantum chemistry was widely used in all branches of chemistry and penetrated into other disciplines related to chemistry. He seized the opportunity to set up courses such as quantum chemistry, molecular spectroscopy and advanced inorganic chemistry, and he visited the front line of teaching personally until 1986. His lectures are rich in content, focusing on inspiring students to go deep into the micro-level of material changes and analyzing complex chemical phenomena by using basic laws, so as to deeply understand the micro-nature of these phenomena and their internal relations, and then foresee some new phenomena. Attach importance to the construction of teaching materials Xu Guangxian attaches great importance to the construction of teaching materials, and thinks that good teaching materials are of great help to students' study.
In 1950s, according to the material structure lecture notes he had used in Peking University for several years, he revised and supplemented them, carefully arranged them, and compiled the book Material Structure, which was published by Higher Education Press as 1959, and was designated as a national unified textbook by the Ministry of Higher Education.
1965, in order to meet the teaching needs of engineering and normal colleges, he compiled a concise course of material structure. The book "Material Structure" is rich in content, well-organized, well-organized and accurate in concept expression, among which two chapters on chemical bond theory are particularly brilliant. Therefore, it is welcomed by teachers and students and has become a teaching material used for many years in the country. It has been reprinted five times, and more than 0,000 copies of/kloc-0 have been issued, which has played an important role in the teaching of material structure.198865438+10. The book was reprinted in Hong Kong and was welcomed by readers in Hong Kong and Taiwan.
In the early 1980s, with the help of Wang Xiangyun, he revised and supplemented the original book according to the development of the subject of material structure. The revised version was published by Higher Education Press as 1987, which was very popular with readers.
1978, when Xu Guangxian offered a quantum chemistry class for graduate students, he cooperated with Li Lemin to compile the graduate quantum chemistry textbook "Basic Principles and Ab initio Method of Quantum Chemistry" (the first, middle and second volumes), which were published in 1980, 1985 and 6544 respectively, aiming at the weak foundation of mathematics and physics for chemistry undergraduates. This textbook is rich in content, can fully reflect the development status of this subject, and is quite detailed in the description of basic principles and formula derivation. It is easy for readers with weak foundation in mathematics and physics to understand, so it is well received by readers.
In addition, he has published many articles on the exchange of teaching experience or special lectures in magazines such as Chemical Bulletin, which has also benefited many teachers and students.