Lead lanthanum zirconate stannate titanate （PLZST） powders with homogeneous composition were synthesized at a relatively low temperature of 650 ℃ by a citrate process based on the Pechini method. Clear aqueous solu...Lead lanthanum zirconate stannate titanate （PLZST） powders with homogeneous composition were synthesized at a relatively low temperature of 650 ℃ by a citrate process based on the Pechini method. Clear aqueous solutions were prepared from inorganic salts, and citric acid was added as a chelating agent to attain precursor sols. Dried gel-precursors were calcined at different temperatures for various time. The perovskites powders were obtained at 650 ℃ for 1 hour. XRD and SEM results show that the powders were single-phase and ultrafine particles.展开更多
The pure phases of alkaline earth molybdates MMoO 4, where M=Mg, Ca, Sr or Ba, were synthesized via the calcination of the related citrato oxomolybdate complexes. The mixed metal oxides can be highly dispersed at the...The pure phases of alkaline earth molybdates MMoO 4, where M=Mg, Ca, Sr or Ba, were synthesized via the calcination of the related citrato oxomolybdate complexes. The mixed metal oxides can be highly dispersed at the atomic level due to the existence of uniform citrato oxomolybdenum precursors in definite composition. The complexing effect helps to produce the fine-grained oxides with particle size in the ultrafine scale(<100 nm) at heat-treatment temperatures below 500 ℃. The structures of the precursor complexes and the finally heat-treated particles were studied by means of IR, XRD, DSC, DTA and TG techniques. The morphologies of the particles were observed by using the SEM technique. The average particle sizes were calculated to be in the range of 30_50 nm based on X-ray diffraction line-broadening and SEM images, indicating the poor conglomeration of crystallite at low temperatures.展开更多
Cubic （Zn,Li）TiO3 powders were synthesized through a modified sol-gel route including the Pechini process via a three-step heat treatment.The as-synthesized （Zn,Li）TiO3 could be stable up to 1000 °C.The diele...Cubic （Zn,Li）TiO3 powders were synthesized through a modified sol-gel route including the Pechini process via a three-step heat treatment.The as-synthesized （Zn,Li）TiO3 could be stable up to 1000 °C.The dielectric constant and dielectric loss tangent of all the synthesized （Zn,Li）TiO3 samples at different measurement frequencies showed the similar tendency.At the same frequency,the dielectric constant and the dielectric loss tangent of （Zn,Li）TiO3 samples decreased and increased,respectively,with the lithium doping content increase.The as-prepared （Zn,Li）TiO3 showed improved microwave dielectric properties,and its maximum value of quality factor could reach 34000 GHz.展开更多
基金the National Natural Science Foundation of China(No.50272030)
文摘Lead lanthanum zirconate stannate titanate （PLZST） powders with homogeneous composition were synthesized at a relatively low temperature of 650 ℃ by a citrate process based on the Pechini method. Clear aqueous solutions were prepared from inorganic salts, and citric acid was added as a chelating agent to attain precursor sols. Dried gel-precursors were calcined at different temperatures for various time. The perovskites powders were obtained at 650 ℃ for 1 hour. XRD and SEM results show that the powders were single-phase and ultrafine particles.
基金the Foundation of the Ministry of Science and Technology of China(No.G19990 2 2 4 0 8and0 0 1CB10 890 6 )
文摘The pure phases of alkaline earth molybdates MMoO 4, where M=Mg, Ca, Sr or Ba, were synthesized via the calcination of the related citrato oxomolybdate complexes. The mixed metal oxides can be highly dispersed at the atomic level due to the existence of uniform citrato oxomolybdenum precursors in definite composition. The complexing effect helps to produce the fine-grained oxides with particle size in the ultrafine scale(<100 nm) at heat-treatment temperatures below 500 ℃. The structures of the precursor complexes and the finally heat-treated particles were studied by means of IR, XRD, DSC, DTA and TG techniques. The morphologies of the particles were observed by using the SEM technique. The average particle sizes were calculated to be in the range of 30_50 nm based on X-ray diffraction line-broadening and SEM images, indicating the poor conglomeration of crystallite at low temperatures.
基金Supported by the National Natural Science Foundation of China(Nos.20731001,20871015 and 50725415)the Program for New Century Excellent Talents in University,China(NCET)+1 种基金the National Basic Research Program of China(No.2007CB613601)the Program for Changjiang Scholars and Innovative Research Team in University,China(No.IRT0708)
文摘Cubic （Zn,Li）TiO3 powders were synthesized through a modified sol-gel route including the Pechini process via a three-step heat treatment.The as-synthesized （Zn,Li）TiO3 could be stable up to 1000 °C.The dielectric constant and dielectric loss tangent of all the synthesized （Zn,Li）TiO3 samples at different measurement frequencies showed the similar tendency.At the same frequency,the dielectric constant and the dielectric loss tangent of （Zn,Li）TiO3 samples decreased and increased,respectively,with the lithium doping content increase.The as-prepared （Zn,Li）TiO3 showed improved microwave dielectric properties,and its maximum value of quality factor could reach 34000 GHz.
