Rare Earth Eu Doping Preparation And Optical Properties Of Barium Titanate

Perovskite oxide materials have excellent physical effects and properties including typical ferroelectric property,high temperature superconductor property,dielectric property,piezoelectric property and optoelectronic property, which have been always one of hot subjects in the basic science and high new technology studies, therefore, it is important to study this kind of materials. Especially, ferroelectric material BaTiO3 has the typical ABO3 perovskite structure and excellent optoelectronic property,high electrooptic coefficient,low half-wave voltage and epitaxial growth BaTiO3 film has high second harmonics.Various ions-doped BaTiO3 materials have been extensively studied in the material field. Doping with various ions can improve physical property of materials, proper electrical conductivity constant can be acquired by adjusting oxygen content and dopant content. This kind of materials can be applied in various fields widely, particularly, most dopant ions include rare earth ions and transition elements.Previously, some researchers chose rare earth elements as dopant in the modification studies of BaTiO3 ceramics and high quality BaTiO3:R(R=rare earth element) materials had been prepared successfully. Various studies and analysis related to ferroelectric and optoelectronic properties of materials are reported, however, few systematic studies related to optical properties including temperature dependence of photoluminescence (PL) spectroscopy,Raman spectroscopy and electronic structure information about materials are reported. Therefore, based on the above analysis, research works include some aspects were evolved as follows:In this paper,High quality Ba1-xEuxTiO3 materials were prepared by traditional high temperature solid state reaction method, the XRD pattern suggested that the samples are single-phase compounds and SEM image displayed that the samples are high density when dopant content x is small.In order to detect phase transition process of materials deeply, we collected the Raman spectra of Ba1-xEuxTiO3 samples in temperature range from 83 K to 553 K and the excited laser lines were 514.5 nm of Ar+ ions laser and 785 nm of solid laser separately. Experimental results indicated that Raman scattering intensity and Raman peak position were sensitive to temperature and different phases have different temperature functions, especially, abrupt changes related to scattering intensity and peak position exist near the phase transition temperature. Simultaneously, phase transition temperatures that related to BaTiO3 shift to lower temperature as a part of Barium ions are substituted by the trivalent Europium ions. The physical origination of the phase transition temperatures shift has been discussed. Comparing Raman scattering spectra using 514.5 nm and 785 nm as excitation source respectively and electronic Raman phenomenon related to 4fn electronic state of Europium were found, electronic Raman peaks are also sensitive to temperature. Besides, Raman scattering spectra of Ba1-xEuxTiO3 using different excitation sources were also studied systematically. Experimental results suggested that Raman scattering spectra were similar for using different excitation sources and Raman frequency shift with increasing Europium ions content.PL spectra measurements were carried out using 514.5 nm and 325 nm as excitation source separately. Temperature dependence of PL spectroscopy (514.5 nm) studies indicated that PL peak positions are also sensitive to temperature and abrupt changes exist near the phase transition temperature, which is similar to Raman experimental results correspondingly. It implied that PL spectroscopy technology can be used as a new method to probe phase transition process of material.PL spectra of Ba1-xEuxTiO3 (325 nm) results shown that it consist of two parts: one part arises from electronic transitions among the different bands in the BaTiO3 materials; the other part is that PL spectra belong to electronic transitions about Europium ions; PL peak positions shift with increasing Europium ions content.In order to discuss electronic structure information on the surface of materials, X-ray photoelectron spectroscopy (XPS) of Ba1-xEuxTiO3 materials were studied systematically. XPS wide spectra,core-energy level spectra,valence band spectra of Ba1-xEuxTiO3 were studied respectively and chemical composition,chemical state on the material surface and electronic band distributions could be fixed. Besides, various properties about single crystal BaTiO3 were studied and were compared with above experimental results related to polycrystalline materials simultaneously.