Oxide powders of Zr1_xTixO2(x=0-1)solid solutions with micron-sized particles were synthesized via a solution combustion method.The synthesis process and Zr/Ti molar ratio were optimized to produce powders with the te...Oxide powders of Zr1_xTixO2(x=0-1)solid solutions with micron-sized particles were synthesized via a solution combustion method.The synthesis process and Zr/Ti molar ratio were optimized to produce powders with the tetragonal crystal structure.X-ray diffraction,Raman spectroscopy and transmission electron spectroscopy results confirm that a full crystallization microstructure with the single tetragonal phase is obtained after calcination at 600℃while maintaining the crystallite size<30 nm.Zr/Ti oxide mixtures with Zr>67 mol%exhibit a tetragonal crystal structure and the embedding Ti in ZrO2 improves the structure stability.The nitrogen sorption results indicate that the powders possess mesoporous morphology with medium specific surface areas(~10-50 m^2/g).Chemical stability tests show that these powders are relatively stable with negligible removal of titanium and zirconium after elution by 0.5 mol/L HC1.Density functional theory was used to calculate the most stable structure with low energy for the selected composition.展开更多
Mesoporous structured metal oxides exhibit many active applications.However,the synthesis of crystalline metal oxides with a ternary composition while maintaining satisfactory pore features is challeng-ing.Typically,h...Mesoporous structured metal oxides exhibit many active applications.However,the synthesis of crystalline metal oxides with a ternary composition while maintaining satisfactory pore features is challeng-ing.Typically,high temperatures are required which inhibit control of pore structure properties including surface area,pore volume,and pore size.Herein,the synthesis of ternary metal oxides Ln_(2)Ti_(2)O_(7)pos-sessing pyrochlore crystal structure is achieved using a novel technique which combines‘soft’and hard colloid templating strategies.The formed materials are of submicron size and composed of∼25-30 nm product‘building blocks’with good chemical and phase stability.The polycrystalline powders have a high specific surface area(up to 70 m^(2)·g^(-1))and pore volume(∼0.35 cm^(3)·g^(-1))which result in a good adsorp-tion capacity(U uptake closing to 60 mg·g^(-1)).Remarkably,the material exhibits a significant portion of mesopores(mainly 10-40 nm)which facilitate fast adsorption of the cations due to high accessibility.The synthetic methodology described herein produces highly homogenous powders and can be applied to other compositions and structures.展开更多
文摘Oxide powders of Zr1_xTixO2(x=0-1)solid solutions with micron-sized particles were synthesized via a solution combustion method.The synthesis process and Zr/Ti molar ratio were optimized to produce powders with the tetragonal crystal structure.X-ray diffraction,Raman spectroscopy and transmission electron spectroscopy results confirm that a full crystallization microstructure with the single tetragonal phase is obtained after calcination at 600℃while maintaining the crystallite size<30 nm.Zr/Ti oxide mixtures with Zr>67 mol%exhibit a tetragonal crystal structure and the embedding Ti in ZrO2 improves the structure stability.The nitrogen sorption results indicate that the powders possess mesoporous morphology with medium specific surface areas(~10-50 m^2/g).Chemical stability tests show that these powders are relatively stable with negligible removal of titanium and zirconium after elution by 0.5 mol/L HC1.Density functional theory was used to calculate the most stable structure with low energy for the selected composition.
文摘Mesoporous structured metal oxides exhibit many active applications.However,the synthesis of crystalline metal oxides with a ternary composition while maintaining satisfactory pore features is challeng-ing.Typically,high temperatures are required which inhibit control of pore structure properties including surface area,pore volume,and pore size.Herein,the synthesis of ternary metal oxides Ln_(2)Ti_(2)O_(7)pos-sessing pyrochlore crystal structure is achieved using a novel technique which combines‘soft’and hard colloid templating strategies.The formed materials are of submicron size and composed of∼25-30 nm product‘building blocks’with good chemical and phase stability.The polycrystalline powders have a high specific surface area(up to 70 m^(2)·g^(-1))and pore volume(∼0.35 cm^(3)·g^(-1))which result in a good adsorp-tion capacity(U uptake closing to 60 mg·g^(-1)).Remarkably,the material exhibits a significant portion of mesopores(mainly 10-40 nm)which facilitate fast adsorption of the cations due to high accessibility.The synthetic methodology described herein produces highly homogenous powders and can be applied to other compositions and structures.
