IR Transparent Chalcogenide Glasses And Glass-Ceramics Based On GeS₂-Sb₂S₃-PbCl₂ System

Glass crystallization is a research hotspot in glass science.Through controllable crystallization,chalcogenide glass-ceramics can be fabricated which not only retain good IR-transmitting property,but also improve physical properties.Most of the investigations on chalcogenide glasses focused on the basic physical properties of the glass,while the functional design of glass-ceramics with target crystal phases are barely studied.Thus,this work is to find new chalcogenide glass-ceramics suitable for doping rare-earth ions.As a well-known IR optical crystal,PbCl₂ here was chosen to be introduced into chalcogenide glassy matrix and then recrystallized for the fabrication of PbCl₂ nano-crystallized chalcogenide glass-ceramics,which would be a good candidate medium for rare-earth luminescence.In the introduction,the characteristics and applications of chalcogenide glass were briefly introduced.Then,the research progress of chalcogenide glass-ceramics was emphasized.Among them,we focused on halide-doped Ge-Ga-S,Ge-Ga-Se,Ge-Sb-S,Ge-Sb-Se glasses,and glass-ceramics embedded with chalcogenide and halide crystals.In addition,lead halide crystal composited glass-ceramics are also introduced.Finally,the research purpose and significance of this work were proposed.In Chapter 2,the relevant raw materials,experimental instruments and related processes for the preparation of chalcogenide glass were described.The characterization techniques for structural,thermal,optical,mechanical properties were also demonstrated.In Chapter 3,the glass formation,properties and crystallization behavior of GeS₂-Sb₂S₃-PbCl₂system were studied in detail.The glass-forming region can be divided into three regions according to the degree of crystallization,i.e.,glass,glass-ceramic and ceramic region.The solubility behavior of PbCl₂ in GeS₂-Sb₂S₃ chalcogenide glass was discussed for explaining such unique glass-forming region.Two routes for the preparation of glass-ceramics with the precipitation of PbCl₂ crystals were found.One is thermal treatment of the samples in the glass region,and the other is one-step melt-quenching method that chalcogenide glass-ceramics containing PbCl₂ nanocrystal can be directly obtained by adjusting the PbCl₂content of samples in the glass-ceramic region.The latter provides a new approach for preparing chalcogenide glass-ceramic.In Chapter 4,the effect of PbCl₂content on the structure and properties of GeS₂-Sb₂S₃glass network and the spontaneous-crystallization behavior of PbCl₂ in GeS₂-Sb₂S₃ glass were investigated in detail.The transmission,thermal,and physical-mechanical properties of（100-x）（0.5GeS₂-0.5Sb₂S₃）-xPbCl₂（0≤x≤25）samples were characterized and discussed with the increasing PbCl₂.In addition,XRD,SEM and Raman techniques were used to study the spontaneous-crystallization behavior of PbCl₂ when x>10 mol%.It was found that different from the traditional glass crystallization through heat treatment,an interesting oversaturation and recrystallization behavior of PbCl₂ occurred in the studied samples.In Chapter 5,crystallization experiments were performed on various samples that selected specially in the glass-forming region.The precipitation of PbCl₂ nanocrystals further improves the physical properties of the studied samples.The effect of two variables（heat-treated temperature and time）on the crystallization behavior were analyzed,and the growth mechanism of PbCl₂crystals in GeS₂-Sb₂S₃glass matrix was discussed by using Ostwald-ripening theory.Finally,Chapter 6 is to summary the main conclusions drawn from this research work.The glass-forming region of GeS₂-Sb₂S₃-PbCl₂ pseudo-ternary system is determined.The effect of PbCl₂ on the properties and network structure of GeS₂-Sb₂S₃ based glass was analyzed.And two kinds of crystallization behaviors of spontaneous-crystallization and controlled crystallization in GeS₂-Sb₂S₃ chalcogenide glass were explored.In this work,the glass formation,physical properties and crystallization behavior of GeS₂-Sb₂S₃-PbCl₂ were studied in detail to establish the composition-structure-property relationship of chalcogenide glass.Novel PbCl₂ nano-crystallized chalcogenide glass-ceramic material with improved properties was obtained successfully via two different process,i.e.,spontaneous-crystallization and controlled crystallization.We believe that this work would be of a good guiding significance for the future design of functional chalcogenide glass-ceramic.