Oxygen Absence and Its Elimination in Research and Trial Manufacture of PMN-PT Ceramics Zhu Weimin, Li Cheng'en, Zhou Jiaguang, Li Yi (Shanghai Lianneng Science and Technology Co., Ltd., Shanghai 200233, found that the stoichiometric composition (F1) of Pb:Mgi/3NbM ) 0.65Ti0.353 ceramics often exhibit large degradation of the piezoelectric performance, and an appropriate amount of A-position Pb can stably obtain high-performance helium (blade 1/nano 2/3) 0.65 é‚›. 353 ceramics. The results of valence state analysis of XPS elements show that the stoichiometric Pb:Mgi/3NbM)0.65Ti0.353 ceramics contain more oxygen vacancies, and the generation of oxygen vacancy stems from the difference in the atmosphere during the synthesis of MgNb26(MN). A suitable amount of Pb in the A-position can effectively eliminate this oxygen deficiency and stably obtain normal piezoelectric performance. The mechanism is considered to be the combination of oxygen deficiency and lead deficiency. Zhao Tianren, researcher, research direction: preparation, structure, performance and application of functional ceramics; Li Yi (1965-), male, Shaoxing, Zhejiang, chairman, research direction: integration of optical, mechanical and electrical technologies; Zhou Jiaguang (1940) -), Male, Sichuan Jiangyou, associate researcher, research direction for functional ceramic performance testing, application and testing methods. The PMN-PT ceramic in the bookmark5) area is considered to be a highly promising material for high-performance sensors and actuators because of its large piezoelectric coefficient, electromechanical coupling coefficient 33, and dielectric coefficient £33. In the actual preparation process, the performance of the material fluctuates greatly, taking the piezoelectric coefficient 3 as an example. According to the report, for the PMN-PT ceramics with the same composition and in the MPB region, the height can reach 720pC/N, and the low is only 470pC. / N. According to the results of the author's experiment and with some of the personnel involved in the preparation of PMN-PT ceramics or single crystals and the exchange of researchers, it was found that the use of conventional electronic ceramic preparation process (composition with precursor synthesis X stoichiometry is more difficult to obtain For PMN-PT ceramics with normal performance, PMN-PT ceramics with poor piezoelectric performance (only 3,330 pC/N Zuoli) are often obtained, and XRD results show that these ceramics do not contain pyrochlore phases. There are other factors outside the pyrochlore phase that strongly affect the performance of PMN-PT ceramics, so it is necessary to further study the factors that affect the piezoelectric properties of PMN-PT ceramics. 1 Experiments Four different Pb compositions were selected (Table 1). PMN-PT ceramics were prepared using precursor synthesis and conventional electronic ceramic preparation processes. The specific process was as follows: (MgCO) 4Mg(OH)25H2O with stoichiometric tb. Nb2O5 was mixed by ball milling and then calcined at 1150C for 6h to synthesize MN. The synthesized MN and stoichiometric ratio of TiO2 and different amounts of Pb3O4 were then planetary milled and mixed for 4 hours and then synthesized at 850C for 4 hours. Fine grinding (planetary ball milling) After 5 h), the powder was molded under the pressure of 15 MPa, sintered and then processed into 012 mm x 1 mm wafers, and the polarization state was studied. The XPS full spectrum of the full XPS of PMN-PT(A) is very similar, in this case combined with energy/eV out) XPS-XPS 60C silicone oil of the Nb element in the sample after firing - 8 series ceramics, voltage is 3x103V/mm, holding time 10min. After standing for 24h, conduct piezoelectric, dielectric properties test. Sample Composition Lead Content Color Chemistry è£åŒ• Dark Gray Chemical è£åŒ• Yellow Excess Dark Gray Deficient 1% Yellow Yellow Deficiency 2% Yellow Utilization Shen E Old Scientific Instrument Factory NP-1 X-ray Photoelectron Spectrometer, Determination of PMN-PT Ceramics The binding energy of the element. 2 Piezoelectric and dielectric properties after the results and discussion, in which PMN-PT-8(A) is a PMN-PT ceramic whose performance is greatly degraded, and PMN-PT-8 is an occasionally-made PMN-PT with normal performance. ceramics. According to Table 1 and Table 2, although the composition of PMN-PT-8 is the same and the preparation process is the same (precursor synthesis method and conventional electronic ceramic preparation process), the piezoelectric and ferroelectric properties are quite different. After PMN-PT-8 was annealed, tg5, p-free, must-be-3, and cauldron 30 increased significantly and 2m decreased significantly; PMN-PT-8 did not change much before and after annealing, indicating PMN-PT-8. Oxygen deficiency may exist in (A), because the presence of oxygen vacancies is conducive to the rise of 2m, the decrease of tg5, annealing in oxygen atmosphere or in air is an effective method to eliminate oxygen vacancies' Table 2 PMN-PT ―8 series ceramic piezoelectric, dielectric properties (sintering temperature 1220 °C; sintered sample density is greater than the theoretical density of 97%) samples In the experiments in this article, the synthesis of MgNb26 precursor is performed in open helium Powder synthesis, so the atmosphere on the surface of the crucible may be different from the atmosphere on the bottom of the crucible. In comparison, the atmosphere at the bottom of the crucible is even worse. Under high temperature (1100C), helium oxidizing atmosphere, and long-term heat preservation (6h), Nb5+ may be partially reduced to Nb4+. If Nb4+ is present in the sample, Nb4+ is likely to occupy the original Nb5+ B position in the perovskite structure due to the very close ionic radius of Nb5+ and Nb4 (Nb5+ is 0.070 nm and Nb4+ is 0.074 nm). This will produce oxygen deficiency in the sample. Position to maintain the electrical neutrality of the sample. According to Hardtl's experimental results, Mn doping in PLZT can eliminate ion vacancies in samples. The absence of intrinsic ions in PLZT is lead deficiency; Mn occurs in ceramics in the form of Mn2+ or Mn3+ doping instead of B. The ion, the B site ion in the perovskite structure is 4 valence, so the Mn substitution will produce an oxygen vacancy. The absence of lead and the absence of oxygen have opposite charges. Hardtl's experimental results suggest that there is indeed a possibility that when lead deficiency and oxygen deficiency meet, they are compounded. Therefore, in the experiment, whether there is a combination of lead deficiency and oxygen vacancy in PMN-PT-8-E and PMN-PT-8-F and their performance and PMN-PT-8(A) Compared with PMN-PT-8-L, changes have occurred. In order to confirm the above point of view, XPS (X-ray Photoelectron Spectroscopy) was used to fine-spectrum the Nb elements of PMN-PT-8 series ceramics and PMNPT8E. The two peaks of PMN PT-8-L in the figure are the characteristic peaks of a pair of inner electrons of Nb atoms when the Nb element is in a certain binding state, and the peak of 208.8 eV corresponds to the Nb atom in this combined state. The binding energy of the inner 3d3/2 electrons, the peak of 206eV corresponds to the binding energy of the inner electrons of 3d5/2 of Nb atoms. With the composition of PMN-PT-8-L plus PbO into the stoichiometric ratio of PMN-PT-8 (A), the characteristic bimodal peak shape of the Nb element changes, and the left side of the 3d5/2 peak (high binding) There can be a shoulder step, indicating that there may be a new Nb atom binding state. When the composition of the stoichiometric ratio of PMN-PT-8 to the Pb-deficient PMN-PT-8-E, the peak position of the Nb to the high binding energy /EV圄3PMN-PT ceramic fired sample O The XPS spectrum of the element can be moved very clearly (higher binding energy 206.5 eV and 209.3 eV peaks appear on the left side of the 3d5/2 and 34/2 peaks, respectively). The high binding energy peak corresponds to a high atomic number. state. It is shown that there are more (5-x) valence Nb ions in PMN-PT-8-L than PMN-PT-8-E, which is the reason why oxygen vacancies are formed around Nb ions. The formation of oxygen vacancies can be represented by the following formula: the limitation of the preparation, the sound of the spectral lines is large, and the spectral lines cannot be analyzed. Analyze the element's 1S characteristic peak (single peak). The asymmetry of the spectral lines in the figure indicates that the spectral line is formed by the superposition of multiple peaks, and then the O atom has more than one binding state. According to the composition, PMN - PT - 8 - L (incorporating excess Pb in the composition) to PMN - PT - 8 (A) (stoichiometry X to PMN - PT - 8 - E (Pb is missing in the composition) The variation of the two XPS peaks of O element is that the intensity of the peak at the low binding energy increases and the intensity of the peak at the high binding energy decreases.The enhancement of the intensity of the O peak at the low binding energy indicates a higher effective negative charge The amount of O ions increases, and the O peak at high binding energy indicates that the O ion is in the unsaturated valence state, ie, the (-2+x) valence, which is the cause of oxygen vacancies. Compared with ―8―E, PMN ―PT―8―L contains more oxygen vacancies, which is consistent with the previous analysis of Nb elements.) There are more oxygen vacancies in the sample. The lead's PMN-PT-8-E has a combination of oxygen vacancies and lead vacancies, eliminating oxygen vacancies. Oxygen deficiency with charge can be easily enriched in the domain wall under the action of the electric field, pinning the domain wall, preventing the movement of the domain wall and reducing the piezoelectric properties of the material. 3 Conclusions Due to process variations, stoichiometric ratios of PMN-PT ceramics may contain more oxygen vacancies. The preparation of a small amount of lead-deficient PMN-PT ceramics at the A site can eliminate this oxygen deficiency, and its mechanism is the combination of oxygen vacancy and lead vacancy. ) The elimination of oxygen vacancies in PMN-PT ceramics helps to increase the piezoelectric constant, dielectric constant, and electromechanical coupling coefficient of the material.
Round Fixing Magnet, or Bushing Fixing Magnet, socket bushing magnet or Insert magnet holder.The round fixing magnet, is a magnetic insert assembly mainly used for holding concrete formworks which made of steel,or holding tools. Its` magnetic force is range from 4 kg ~ 70kgs, which could hold steel structures steadily.
The Round fixing magnet, is made of Neodymium Magnet , steel armature and steel thread rod. The neodymium magnet is plated with NI-CU-NI treatment,the steel armature is treated with Zinc coating, the thread rod is coated with black epoxy. These surface treatment could offer good anti corrosion protections for the bushing fixing magnets.
The strongest permanent magnet-NdFeB magnets are used in the embeded socket fixing magnet. The NdFeb magnet are plated with NiCuNiand the metal cup could be plated with color Zinc or other treatments to well protect the metal cup from
corrosion. The magnet contact surface
should be clean and flat otherwise the actual magnetic force will be reduced. The max
working temperature of the embeded fixing
magnets is 80 degrees. Please keep the embeded fixing magnets away fire or being
heating. If higher working temperature is needed, the
higher grade NdFeB magnets will be necessary then.The magnetic force and sizes could be designed according to customers' requirements.
Bushing magnet, which configure by a thread hole cup magnet and a separable thread rod to fit the thread hole.Magnetic bushing magnet is made of a strong neodymium magnet,a steel cup and a thread rod. The magnet have been plated with thick coatings to prevent corrosion,please be noted that magnetic bushing assembly is not water proof,bushing magnet could not left in humid environment for months or years.Bushing magnet assembly have very strong magnetic force which could retaining heavy objects.We could produce various sizes of magnet bush assembly. Please kindly inform the model number and quantity when send us inquiry,we could quote soon after calculate the costs.
inserted fixing magnet, a strong Magnetic Assembly for precast concrete industry, it is used to hold neodymium magnet
Inserted fixing magnet,also known as
embeded fixing magnet, inserted socket fixing magnet,
embeded socket fixing magnet, magnetic pipe
ixing magnet,precast concrete fixing magnet.is the new magnetic assembly in precast concrete industry. It is the
best solution to fix the
inserted socket in precast concrete panel.
Magnetic Bushing Assembly Insert Fixing Magnet,Round Fixing Magnet,Embeded Fixing Magnet,Bushing Fixing Magnet NINGBO SHINE MAGENETIC TECHNOLOGY CO.,LTD , https://www.shinemagnets.com
