Ln₂S₃-based Diluted Magnetic Semiconductors And The High-pressure Phase Transition Study Of Several Sulfide

It is well known chalcogenides exhibit the unipue physical and chemicalproperties leading to broad application in many fields, is a kind of very importantsemiconductor material. In₂S₃has a widely application in the field of photoelectron,optical, solar due to the novel structure and properties. And rare-earth sulfide showstheir unique optical, acoustics, electricity, magnetism, thermal properties and haswidely application in rhese aspects due to the special structure of outer electrons. Itwas well known that nano structure materials show the different properties due to sizeeffect and so on, and the structure of small size can be used as a tiny unit ofmicro/nano decive, playing an important role in the properties. Thus, the study of size,structure, change of structure and synthetic method has important value for the studyof the properties of nanomatrrials. By changing the size of nanomaterials can achievecontrol of the band width of nanocrystalline, thus achieved the adjusting of theproperties of nanomaterials without changing the material composition, phasestructure. This is an effective method on modification of materials. And the dopingof nanomaterials is another effective on modification of materials. The materials cansimultaneously controlling charges and spins, show the characteristics ofsemiconductor and magnetic materials which leads to potential application in the fieldof spintronic devices. This is the observed changes from the angle of macroscopicproperties, the doping influence of different concentrations and different element onthe internal electronic structure and lattice structure is different from a tiny microangle, leading to the different properties under different doping conditions. Thus, thestudies of different doping conditions contribute to the further development of dilutedmagnetic semiconductors.In addition, high-pressure technology is an important means to study the changeof internal lattice structure under the extreme conditions. Using high-pressuretechnology can clearly found that the differences of different lattice structure. Thecomparative study on the undoped and doping samples can intuitive find that theeffect of doping on lattice structure embodies in the high-pressure phase transitionprocess of samples.In this paper, the In₂S₃nanoparticles with small size have been synthetized using the simple cheap repeatability of gas liquid phase chemical deposition method, andthe In₂S₃based dilute magnetic semiconductor（DMSs） with different magneticproperties also have been prepared using the controlling of doping concentration andelements, and analysis of the sources of magnetism and magnetic mechanism; thenIn₂S₃, In₂S₃based DMSs and several rare-earth sulfide carried out the study ofhigh-pressure synchrotron radiation by the high-pressure synchrotron radiationtechnology. The main content as follow:In₂S₃、In₂S₃:Eu with different Eu content and In₂S₃:Ce nanoparticles weresynthesized by gas-liquid phase Chemical deposition. The phase, microstructures, andchemical composition analyses of the In₂S₃nanoparticles show the characteristics ofhigh purity, small size （5-6nm） by X-ray diffraction, high resolution transmissionelectron microscopy （HRTEM）, and X-ray photoelectron spectroscopy （XPS）. Thephotoluminescence （PL） emission spectra displays the spectra of In₂S₃、In₂S₃:Eu andand In₂S₃:Ce appear blue shift. The decrease of the particle causes level spacingincreases, move to the shortwave spectrum. Eu and Ce were introduced into thestructure of In₂S₃lattice structure, increase the defect concentration and quantum sizeeffect, the luminous effect of In₂S₃strengthen and expand the range of visible lightabsorption. The ionic radius of Ce is larger than Eu, larger influence on the latticestructure, causing the better luminous effect of In₂S₃:Ce than In₂S₃:Eu.The magnetic properties of sample were analyzed using vibrating samplemagnetometer, magnetic measurement system and the theory simulation analyzes, anddiscussed the doping effecting on the magnetism. The In₂S₃:Eu with different Eucontent has magnetism. The saturation magnetization increases initially and thendecreases with increasing doped concentration. The saturation magnetization ofIn₂S₃:Eu with Eu content0.99%is the largest. The In₂S₃:Eu shows the complexmagnetic phase transition process as the reduction of temperature. One is thesuperparamagnetism to magnetic long-range order, one is the magnetic long-rangeorder to quantum superparamagnetism. The theoretical simulations show the origin ofmagnetism is Eu, the magnetic mechanism is the Eu f-f exchange interaction withRKKY model. Eu ion concentration determines the type of exchange interaction. Eucontent increased, leading to the antiferromagnetic coupling increases, offset part ofthe ferromagnetic, lower total magnetization.The magnetic properties of sample were analyzed using magnetic measurement system, explored the Ce doping effect on the magnetism. In₂S₃:Ce show the magneticbehavior under at10K,150K, and300K, the hysteresis loops decrease as temperatureincreases, indicating a transition of ferromagnetic to superparamagnetic state. Thefurther research found the In₂S₃:Ce as the decrease of temperature show the same twomagnetic phase transition with In₂S₃:Eu, but the Ce doping improved the temperatureof magnetic phase transition, showing the ferromagnetic at room temperature. This isdue to the larger doping ions leading to larger carrier concentration and thus enhancedthe temperature of magnetic phase transition.In₂S₃and In₂S₃:Ce carried out the study of high-pressure synchrotron radiationby the high-pressure synchrotron radiation technology under the condition of quasistatic water pressure. Through the comparative study to discuss the differences of twohigh pressure phase transition behavior and analyza the reasons, explore the effect ofdoping on the lattice structure of host materials and high-pressure phase transition.The research found that In₂S₃and In₂S₃:Ce have the same transition path from thetetragonal-to-cubic, the phase transition pressure and bulk moduli In₂S₃:Ce is lowerthan that of In₂S₃. The distinct high-pressure behaviors can be explained in term of thedoped ions, causing lattice distortion and reducing structural stability of the In₂S₃nanoparticles and further accelerating the phase transition.La2S3, Ho₂S₃and Tm2S3carried out the study of high-pressure phase transitionby the high-pressure synchrotron radiation technology. Two typical structures ofhigh-pressure phase transition research is helpful for the exploration of the law of rareearth sulfide high-pressure phase transition, to have the same structure of rare earthsulfide of the high pressure phase transition carried on the comparative study ofsulphide. Through the change of cationic elements analyzes the influence on highpressure phase transition, to explore the cause of the high pressure phase transitionbehavior. The La2S3shows the transition path from the orthorhombic to cubic, theHo₂S₃and Tm2S3show the transition path from monoclinic to orthorhombic. Thestudy of Ho₂S₃and Tm2S3found that with the decrease of the cationic radius, thelattice parameters and cell size decreases, and the phase transformation stress pointand body elastic modulus increase.