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Tuning the magnetic and electronic properties of strontium titanate by carbon doping

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Frontiers of physics 2021年第4期16卷 195-204页

作者： Hui Zeng Meng Wu Hui-Qiong Wang Jin-Cheng Zheng Junyong Kang Fujian Provincial Key Laboratory of Semiconductors and Applications Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient DevicesDepartment of PhysicsXiamen UniversityXiamen 361005China Xiamen University Malaysia Sepang 43900SelangorMalaysia

The magnetic and electronic properties of strontium titanate with different carbon dopant configurations are explored using first-principles calculations with a generalized gradient approximation(GGA)and the GGA+U approach.Our results show that the structural stability,electronic properties and magnetic properties of C-doped SrTiO3 strongly depend on the distance between carbon dopants.In both GGA and GGA+U calculations,the doping structure is mostly stable with a nonmagnetic feature when the carbon dopants are nearest neighbors,which can be ascribed to the formation of a C–C dimer pair accompanied by stronger C–C and weaker C–Ti hybridizations as the C–C distance becomes smaller.As the C–C distance increases,C-doped SrTiO3 changes from an n-type nonmagnetic metal to ferromagnetic/antiferromagnetic half-metal and to an antiferromagnetic/ferromagnetic semiconductor in GGA calculations,while it changes from a nonmagnetic semiconductor to ferromagnetic half-metal and to an antiferromagnetic semiconductor using the GGA+U method.Our work demonstrates the possibility of tailoring the magnetic and electronic properties of C-doped SrTiO3,which might provide some guidance to extend the applications of strontium titanate as a magnetic or optoelectronic material.

关键词： strontium titanate carbon doping magnetic and electronic states carbon coupling C-C dimer pair GGA+U

AC Complex Impedance Analysis of Doped strontium titanate Multifunctional Ceramics

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Journal of Materials Science & Technology 2002年第5期18卷 479-480页

作者： QingXU WenCHEN DuanpingHUANG RunzhangYUAN Sch. of Mat. Sci. and Eng. Wuhan Univ. of Technol. Wuhan 430070 China

Doped SrTiO3 capacitor-varistor multifunctional ceramics were fabricated by a single sintering process. AC complex impedance analysis was performed to investigate electrical features of grains and grain boundaries for both as-reduced ceramic and reoxidized ceramics. The results showed that the as-reduced ceramic exhibited inductive response at high frequencies above 2 MHz, which is attributed to the contribution of electron behavior in semiconducting grains. The high frequency inductive response disappeared in impedance plots of reoxidized ceramics.

关键词： strontium titanate Impedance Grain Capacitor

Limiting current oxygen sensor based on Y,In co-doped SrTiO_(3)as a dense diffusion barrier layer

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Nano Research 2022年第6期15卷 4880-4885页

作者： Ke Shan Zhongzhou Yi Jing Wang College of Science Honghe UniversityMengzi 661199China

A novel dense diffusion barrier material(Y_(x)Sr_(1−x)Ti_(0.9)In_(0.1)O_(3−δ)(x=0.03,0.05,0.07))was prepared by using a sol-gel method.The crystal structure,microstructures,electrical conductivity and ionic conductivity of barrier material were characterized.The results show that the samples exhibit the formation of cubic perovskite structure phase.The increase of Y-doping amount on A-site improved electrical conductivity and sinterability of materials.A limiting current oxygen sensor based on Y_(0.07)Sr_(0.97)Ti_(0.9)In_(0.1)O_(3–δ)as a dense diffusion barrier shows excellent sensing performance.The linear relationship between limiting current logIL and 1000/T can described logIL=4.603,8−3.847,5·1,000/T.At 750°C,0.25%≤x(O_(2))≤5.0%,the linear relationship between limiting current(IL)and oxygen amount(x(O_(2)))can described as I_(L)=7.047,6+3.875,1·x(O_(2)).

关键词： limiting current oxygen sensor dense diffusion barrier strontium titanate mixed conductivity

Scalable Preparation of SrTiO_3 Submicro-wires from Layered titanate Nanowires

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Chinese Journal of Aeronautics 2007年第2期20卷 177-180页

作者： TANG Mao-yu JI Tian-hao XIE Jian School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

SrTiO3 submicro-wires were prepared by the reaction of layered titanatc nanowircs with Sr（OH）2 powder in an autoclave. The wires were investigated using X-ray diffraction （XRD）, scanning electron microscope （SEM）, transmission electron microscope （TEM）, Ultra-violet visible （UV-vis）, photoluminescence （PL） and Raman spectroscopy. The XRD measurement shows that the prepared SrTiO3 submicro-wircs hardly have impurity phases. The SEM and TEM images demonstrate that the scalable wires, which need to be processed at the reaction temperature of 180℃ for about 48 hours, are not composed of single crystals. The PL shows that the wire-like SrTiO3 has emission peaks at the wavelengths of 568 and 585 nm. Further, the Raman spectroscopy reveals structural changes in the products through different reaction time.

关键词： oxide titanate nanowires strontium titanate SrTiO3 wires

Synthesis of crystalline perovskite-structured SrTiO_3 nanoparticles using an alkali hydrothermal process

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International Journal of Minerals,Metallurgy and Materials 2016年第1期23卷 109-115页

作者： U.K.N.Din T.H.T.Aziz M.M.Salleh A.A.Umar Institute of Microengineering and Nanoelectronics (IMEN) Universiti Kebangsaan Malaysia

We report an experimental route for synthesizing perovskite-structured strontium titanate （SrTiO3） nanocubes using an alkali hydrothermal process at low temperatures without further heating. Furthermore, we studied the influence of heating time （at 180℃） on the crystallinity, morphology, and perovskite phase formation of SrTiO3. The SrTiO3 powder, which is formed via nanocube agglomeration, transforms into cubic particles with a particle size of 120--150 nm after 6 h of hydrothermal sintering. The crystallinity and percentage of the perovskite phase in the product increased with heating time. The cubic particles contained 31.24at% anatase TiO2 that originated fi＇om the precursor. By varying the weight ratio of anatase TiO2 used to react with the strontium salt precursor, we reduced the anatase-TiO2 content to 18.8at%. However, the average particle size increased when the anatase-TiO2 content decreased.

关键词： strontium titanate nanoparticles anatase hydrothermal synthesis

Fabrication and Magnetic Property of One-dimensional SrTiO_3/SrFe_(12)O_(19) Composite Nanofibers by Electrospinning

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Journal of Materials Science & Technology 2011年第11期27卷 996-1000页

作者： Qingrong Liang Xiangqian Shen Fuzhan Song Mingquan Liu School of Material Science and Engineering Jiangsu University Zhenjiang 212013 China

The composite nanofibers of SrTiO3/SrFel2O19 with a molar ratio of 1：1 and diameter about 120 nm were prepared by electrospinning. Effects of calcination temperature on the formation, crystallite size, morphology and magnetic property were studied by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. The binary phase of strontium ferrite and titanate was formed after being calcined at 900℃ for 2 h and the composite nanofibers were fabricated from nanograins of SrTiO3 about 24 nm and SrFel2O19 around 33 nm. The crystallite sizes for the nanofibers increase with increasing calcination temperature and the addition of SrTiO3 has an obvious suppression effect on SrFel2O19 grain growth. The specific saturation magnetization and remanence tend to increase with the crystallite size. With increasing calcination temperature from 900 to 1050℃, the coercivity increases initially, achieving a maximum value of 520.2 kA.m^-1 at 950℃, and then shows a reduction tendency.

关键词： Composite nanofibers strontium ferrite strontium titanate Electrospinning Magnetic property

Synthesis of SrTiO_3 for immobilization of simulated HLW by SHS

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Journal of University of Science and Technology Beijing 2005年第4期12卷 357-359页

作者： Ruizhu Zhang junjie Hao Zhimeng Guo Materials Science and Engineering School University of Science and Technology Beijing Beijing 100083 China North China Institute of Water Conservancy and Hydroelectric Power Zhengzhou 450045 China

strontium titanate synroc samples were synthesized by self-propagating high-temperature synthesis （SHS）. Sr directly took part in the synthesis process. As a result, the loading content issue is basically resolved. The products were characterized by density, microhardness X-ray diffraction, and scanning electron microscopy （SEM/EDS）. The leaching rate was measured by the method of PCT （product consistency test）. The results indicate that the Sr^2＋-SrTiO3 compound is of high density, low leach rate and high stability and the synthesis process is feasible in technology and economy. It can be concluded that the strontium titanate synroc is a perfect material to immobilize HLW.

关键词： strontium titanate high-level waste （HLW） immobilization self-propagating high-temperature synthesis （SHS）

Ultrahigh electrical conductivities and low lattice thermal conductivities of La,Dy,and Nb Co-doped SrTiO3 thermoelectric materials with complex structures

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Journal of Materials Science & Technology 2020年第17期52卷 172-179页

作者： Daquan Liu Yanxia Wang Xue Jiang Huijun Kang Xiong Yang Xiaoying Zhang Tongmin Wang Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian116024China Key Laboratory of Material Modification by Laser Ion and Electron Beams(Dalian University of Technology)Ministry of EducationDalian116024China

Microstructural modifications and appropriate element doping are necessary to simultaneously enhance the electrical conductivities and reduce the lattice thermal conductivities of thermoelectric materials.Herein,we propose a strategy of multielement doping combined with a burial sintering process to promote thermoelectric properties.Three-element doped Sr0.9La0.05Dy0.05Ti1-xNbxO3(x=0,0.05,0.10,0.15,and 0.20)powders were synthesized by high-energy ball milling,and corresponding bulk samples were prepared by carbon burial sintering.In the bulk samples,we obtained the desired microstructures composed of shell-vesicular architectures with dense dislocations and second phase particles.These materials had ultrahigh electrical conductivities(~5300 S cm^-1 at 300 K),low lattice thermal conductivities(~1.6 Wm^-1 K^-1 from 700 to 1100 K when x=0.2)and low total thermal conductivities(minimum value of 2.95 Wm^-1 K^-1 when x=0.05 at 1100 K).The maximum zT values were 0.28 when x=0.05 and 0.27 when x=0.2 at 1100 K.This strategy provides a possible direction for improving the thermoelectric properties of SrTiO3 based materials.

关键词： strontium titanate Mechanical alloying Thermoelectric material Dense dislocation Sintering process

Enhancement of thermoelectric properties of SrTiO3/LaNb–SrTiO3 composite by different doping levels

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Chinese Physics B 2018年第4期27卷 117-122页

作者：王柯鲜王俊李艳邹涛王晓欢李建波曹正师文静新巴雅尔 School of Materials Science and Engineering Inner Mongolia University of Technology Hohhot 010051 Inner Mongolia Autonomous Region China School of Chemical Engineering Kang Ba Shi Qu Ordos Ordos Institute of Technology Ordos 017000 Inner Mongolia Autonomous Region China Beijing Center for Physical & Chemical Analysis No. 27 Xi Sanhuan Road Haidian District Beijing 100089 China

strontium titanate（STO）is an n-type oxide thermoelectric material,which has shown great prospects in recent years.The doping of La and Nb into STO can improve its power factor,whereas its thermal conductivity is still very high.Thus,in order to obtain a high thermoelectric figure-of-merit z T,it is very important to reduce its thermal conductivity.In this paper,using a combination of a hydrothermal method and a high-efficiency sintering method,we succeed in preparing a composite of pure STO and La Nb-doped STO,which simultaneously realizes lower thermal conductivity and higherSeebeck coefficient,therefore,the thermoelectric properties of STO are significantly improved.In the SrTiO3/La Nb–SrTiO3 bulk samples,the lowest thermal conductivity is 2.57 W·m^-1·K^-1 and the highest z T is 0.35 at 1000 K for the STO/La（10）Nb（20）–STO sample.

关键词： thermoelectric materials SrTiO3/LaNb-SrTiO3 composite hydrothermal method strontium titanate