The densification and microstructure of different spinelized magnesium aluminate spinels（MAS） were studied adding Sc_2O_3 as additive. Sintered products were then characterized in terms of densification, phase analy...The densification and microstructure of different spinelized magnesium aluminate spinels（MAS） were studied adding Sc_2O_3 as additive. Sintered products were then characterized in terms of densification, phase analysis, quantitative elemental analysis and microstructure. The results show that Sc_2O_3 is found to be beneficial for the densification of MAS. Sc_2O_3 has a more significant effect on the densification of partially spinelized MAS batch than that of fully spinelized MAS batch. At the sintering temperature of 1650 °C, the bulk density of sintered products of partially spinelized powders increases by 0.243 g/cm3 as the Sc_2O_3 content increases from 0 to 4%（mass fraction） and that of fully spinelized powder increases by 0.14 g/cm3. Compared with the sintered samples prepared from the fully spinelized powder, the sintered samples using the partially spinelized powders as raw materials have more compact microstructures.展开更多
Recently, lanthanide-ion-doped luminescent materials have been extensively used as optical thermometry probes due to their fast responses, non-contact, and high sensitivity properties. Based on different responses of ...Recently, lanthanide-ion-doped luminescent materials have been extensively used as optical thermometry probes due to their fast responses, non-contact, and high sensitivity properties. Based on different responses of two emissions to temperature, the fluorescence intensity ratio(FIR) technique can be used to estimate the sensitivities for assessing the optical thermometry performances. In this study, we introduce different doping concentrations of Eu^(3+) ions into negative thermal expansion material Sc2W3O12to increase the thermal-enhanced luminescence from 373 K to 548 K, and investigate the temperature sensing properties in detail. All samples can exhibit their good luminescence behaviors thermally enhanced.The emission intensity of Sc2W3O12:6-mol% Eu3+phosphor reaches 147.8% of initial intensity at 473 K. As the Eu3+doping concentration increases, the resistance of the sample to thermal quenching decreases. The FIR technique based on each of the transitions 5D→7F_(1)(592 nm) and 5D→7F_(2)(613 nm) of Eu3+ions demonstrates a maximum relative temperature sensitivity of 3.063% K-1at 298 K for Sc_(2)W_(3)O_(12):6-mol% Eu3+phosphor. The sensitivity of sample decreases with the increase of Eu3+concentration. Benefiting from the thermal-enhanced luminescence performance and good temperature sensing properties, the Sc_(2)W_(3)O_(12):Eu^(3+)phosphors can be used as optical thermometers.展开更多
Transparent phosphor ceramics have received increasing attention for high-brightness laser lighting,but commercially available phosphor ceramics are currently mainly limited to yellow YAG:Ce and green LuAG:Ce garnets,...Transparent phosphor ceramics have received increasing attention for high-brightness laser lighting,but commercially available phosphor ceramics are currently mainly limited to yellow YAG:Ce and green LuAG:Ce garnets,leaving a“cyan cavity”which is an obstacle to realizing full-color lighting.Achieving new phosphor ceramics capable of filling the cavity is a challenge.Herein,for the first time,cyan-green-emitting Ca_(3)Sc_(2)Si_(3)O_(12):Ce^(3+)(CSS:Ce)transparent ceramics have been successfully developed by two-step sintering technique under vacuum.The as-prepared CSS:Ce ceramics present high relative density of 99.7%and optical transmittance of 71%in the cyan-green spectral region.It exhibits an efficient band emission peaking at 504 nm(under 450 nm excitation)with internal/external quantum efficiency of 91%/62%.Furthermore,it has excellent thermal stability with a thermal quenching temperature(T_(0.5))of 838 K,approximately 100 K higher than that of LuAG:Ce ceramics(738 K).In addition,the CSS:Ce ceramics can withstand blue laser density of 45.6 W/mm^(2)and meanwhile generates cyan-green light with a forward luminous flux of 813 lm and forward luminous efficacy of 162 lm/W.The CSS:Ce transparent ceramics exhibit excellent luminescence performance comparable to the commercial LuAG:Ce ceramics and could be a highly promising color converter for high-brightness laser lighting.展开更多
Sesquioxides such as Y_(2)O_(3)and Sc_(2)O_(3)are important optical materials,but the fabrication of their transparent ceramics remains a challenge due to the ultra-high melting point of over 2400℃.In this work,a ser...Sesquioxides such as Y_(2)O_(3)and Sc_(2)O_(3)are important optical materials,but the fabrication of their transparent ceramics remains a challenge due to the ultra-high melting point of over 2400℃.In this work,a series of(Y_(1−x)Scx)_(2)O_(3)transparent ceramics were successfully fabricated by a simple vacuum sintering process without any sintering additives,and the effect of scandium(Sc)content(x)on the crystal structure and optical/thermal/mechanical properties was evaluated.Y_(2)O_(3)and Sc_(2)O_(3)form a complete solid solution with a cubic bixbyite structure.The formation of(Y_(1−x)Scx)_(2)O_(3)solid solution promotes the densification of ceramics,leading to the realization of high transparency close to the theoretical transmittance over a wide wavelength range of 0.35–8μm.In particular,the in-line transmittance in the range of 0.6–6μm remains above 80%for(Y_(1−x)Scx)_(2)O_(3)with x=0.23–0.31,while the pristine Y_(2)O_(3)and Sc_(2)O_(3)are opaque.Moreover,the mechanical properties including Vickers hardness(HV),fracture toughness(KIC),and biaxial flexural strength(δb)are evidently enhanced due to the solid solution strengthening,while the thermal conductivity(k)is reduced due to the reduction of photon free path.This study demonstrates that forming of solid solution is a facile and universal approach for preparing sesquioxide transparent ceramics with high optical and mechanical quality.展开更多
Sc_(2)O_(3)was successfully extracted and separated from Bayan Obo tailings by a CaCl_(2)-reductive carbon powder-combinative roasting method.The optimum pro-cess condition was obtained through adjusting specific ef-f...Sc_(2)O_(3)was successfully extracted and separated from Bayan Obo tailings by a CaCl_(2)-reductive carbon powder-combinative roasting method.The optimum pro-cess condition was obtained through adjusting specific ef-fect factors.It is found that Sc_(2)O_(3)with the ratio of 87.51%is leached out under roasting temperature of 800℃for 2 h through adding 73%CaCl_(2),and 20%reductive carbon powder with liquid to solid ratio of 3.Moreover,the specific reaction mechanism during roasting process was investi-gated by thermogravimetric–differential scanning calorimetry(TG-DSC)and X-ray diffraction(XRD)tech-niques.The results show that the main phases(SiO_(2),CaF_(2) and NaFeSi_(2)O_(6))as well as important phases(LiScSi_(2)O_(6),REFCO_(3)and REPO_(4))would turn into new phases(CaFe-SiO_(4),Fe,Ca_(3)(PO_(4))_(2),NaCl,RE_(2)O_(3)and Sc_(2)O_(3))after com-plicated reactions,which effectively break up the original mineral compositions and activate the existing state of containing scandium matter,consequently facilitating the subsequent hydrochloric acid leaching process.展开更多
基金Project(51374240) supported by the National Natural Science Foundation of ChinaProject(2012BAE08B02) supported by the National Science and Technology Pillar Program of China
文摘The densification and microstructure of different spinelized magnesium aluminate spinels（MAS） were studied adding Sc_2O_3 as additive. Sintered products were then characterized in terms of densification, phase analysis, quantitative elemental analysis and microstructure. The results show that Sc_2O_3 is found to be beneficial for the densification of MAS. Sc_2O_3 has a more significant effect on the densification of partially spinelized MAS batch than that of fully spinelized MAS batch. At the sintering temperature of 1650 °C, the bulk density of sintered products of partially spinelized powders increases by 0.243 g/cm3 as the Sc_2O_3 content increases from 0 to 4%（mass fraction） and that of fully spinelized powder increases by 0.14 g/cm3. Compared with the sintered samples prepared from the fully spinelized powder, the sintered samples using the partially spinelized powders as raw materials have more compact microstructures.
基金supported by the National Natural Science Foundation of China (Grant No. 51872327)。
文摘Recently, lanthanide-ion-doped luminescent materials have been extensively used as optical thermometry probes due to their fast responses, non-contact, and high sensitivity properties. Based on different responses of two emissions to temperature, the fluorescence intensity ratio(FIR) technique can be used to estimate the sensitivities for assessing the optical thermometry performances. In this study, we introduce different doping concentrations of Eu^(3+) ions into negative thermal expansion material Sc2W3O12to increase the thermal-enhanced luminescence from 373 K to 548 K, and investigate the temperature sensing properties in detail. All samples can exhibit their good luminescence behaviors thermally enhanced.The emission intensity of Sc2W3O12:6-mol% Eu3+phosphor reaches 147.8% of initial intensity at 473 K. As the Eu3+doping concentration increases, the resistance of the sample to thermal quenching decreases. The FIR technique based on each of the transitions 5D→7F_(1)(592 nm) and 5D→7F_(2)(613 nm) of Eu3+ions demonstrates a maximum relative temperature sensitivity of 3.063% K-1at 298 K for Sc_(2)W_(3)O_(12):6-mol% Eu3+phosphor. The sensitivity of sample decreases with the increase of Eu3+concentration. Benefiting from the thermal-enhanced luminescence performance and good temperature sensing properties, the Sc_(2)W_(3)O_(12):Eu^(3+)phosphors can be used as optical thermometers.
基金National Key Research and Development Project(2019YFC1907402,2021YFC2902505)Science and Technology Special Project of China Minmetals Corporation(Strategic Frontier Technology Research)。
基金This work was partially supported by National Natural Science Foundation of China(Grant Nos.U22A20139,52102192,51772286,11974346,12074373,52072361,and 12074374)National Key R&D Program of China(Grant No.2021YFB3502701)+3 种基金Youth Innovation Promotion Association CAS(Grant No.2020222)Key Research and Development Program of Jilin Province(Grant Nos.20210201024GX,20220101208JC,and 20230101123JC)Changchun Science and Technology Planning Project(Grant No.21ZGY05)the Opening Project Key Laboratory of Transparent Opto-functional Inorganic Material,Chinese Academy of Sciences.
文摘Transparent phosphor ceramics have received increasing attention for high-brightness laser lighting,but commercially available phosphor ceramics are currently mainly limited to yellow YAG:Ce and green LuAG:Ce garnets,leaving a“cyan cavity”which is an obstacle to realizing full-color lighting.Achieving new phosphor ceramics capable of filling the cavity is a challenge.Herein,for the first time,cyan-green-emitting Ca_(3)Sc_(2)Si_(3)O_(12):Ce^(3+)(CSS:Ce)transparent ceramics have been successfully developed by two-step sintering technique under vacuum.The as-prepared CSS:Ce ceramics present high relative density of 99.7%and optical transmittance of 71%in the cyan-green spectral region.It exhibits an efficient band emission peaking at 504 nm(under 450 nm excitation)with internal/external quantum efficiency of 91%/62%.Furthermore,it has excellent thermal stability with a thermal quenching temperature(T_(0.5))of 838 K,approximately 100 K higher than that of LuAG:Ce ceramics(738 K).In addition,the CSS:Ce ceramics can withstand blue laser density of 45.6 W/mm^(2)and meanwhile generates cyan-green light with a forward luminous flux of 813 lm and forward luminous efficacy of 162 lm/W.The CSS:Ce transparent ceramics exhibit excellent luminescence performance comparable to the commercial LuAG:Ce ceramics and could be a highly promising color converter for high-brightness laser lighting.
基金This research was supported by Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ113)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA22010301)。
文摘Sesquioxides such as Y_(2)O_(3)and Sc_(2)O_(3)are important optical materials,but the fabrication of their transparent ceramics remains a challenge due to the ultra-high melting point of over 2400℃.In this work,a series of(Y_(1−x)Scx)_(2)O_(3)transparent ceramics were successfully fabricated by a simple vacuum sintering process without any sintering additives,and the effect of scandium(Sc)content(x)on the crystal structure and optical/thermal/mechanical properties was evaluated.Y_(2)O_(3)and Sc_(2)O_(3)form a complete solid solution with a cubic bixbyite structure.The formation of(Y_(1−x)Scx)_(2)O_(3)solid solution promotes the densification of ceramics,leading to the realization of high transparency close to the theoretical transmittance over a wide wavelength range of 0.35–8μm.In particular,the in-line transmittance in the range of 0.6–6μm remains above 80%for(Y_(1−x)Scx)_(2)O_(3)with x=0.23–0.31,while the pristine Y_(2)O_(3)and Sc_(2)O_(3)are opaque.Moreover,the mechanical properties including Vickers hardness(HV),fracture toughness(KIC),and biaxial flexural strength(δb)are evidently enhanced due to the solid solution strengthening,while the thermal conductivity(k)is reduced due to the reduction of photon free path.This study demonstrates that forming of solid solution is a facile and universal approach for preparing sesquioxide transparent ceramics with high optical and mechanical quality.
基金financially supported by the National High Technology Research and Development Program (No. 2013AA031002)。
文摘Sc_(2)O_(3)was successfully extracted and separated from Bayan Obo tailings by a CaCl_(2)-reductive carbon powder-combinative roasting method.The optimum pro-cess condition was obtained through adjusting specific ef-fect factors.It is found that Sc_(2)O_(3)with the ratio of 87.51%is leached out under roasting temperature of 800℃for 2 h through adding 73%CaCl_(2),and 20%reductive carbon powder with liquid to solid ratio of 3.Moreover,the specific reaction mechanism during roasting process was investi-gated by thermogravimetric–differential scanning calorimetry(TG-DSC)and X-ray diffraction(XRD)tech-niques.The results show that the main phases(SiO_(2),CaF_(2) and NaFeSi_(2)O_(6))as well as important phases(LiScSi_(2)O_(6),REFCO_(3)and REPO_(4))would turn into new phases(CaFe-SiO_(4),Fe,Ca_(3)(PO_(4))_(2),NaCl,RE_(2)O_(3)and Sc_(2)O_(3))after com-plicated reactions,which effectively break up the original mineral compositions and activate the existing state of containing scandium matter,consequently facilitating the subsequent hydrochloric acid leaching process.
