| This thesis includes two parts. Part one gives some backgrounds about this thesis. In this part, the crystal structure and conduction mechanism of NASICON are reviewed. An introduction on the developments for the NASICON-type sold state electrolytes is also gives. Part two deals with the synthesis and characterization of NaTi2(PO4)3-based,LiTi2(PO4)3-based and NaSn2(PO4)3-based mineral sold state electrolytes prepared by high temperature solid state reaction using refined nature pyrophyllite and rare earths oxides as starting materials. The compositions have been characterized by XRD,IR and A.C. impedance technique. Four systems of mineral sold state electrolytes are studied, they are Na1+3x+yAlxNdyTi2-x-ySi2xP3-2xO12,Na1+3x+yAlxYyTi2-x-ySi2xP3-2xO12,Li1+3x+yAlxLayTi2-x-ySi2xP3-2xO12 and Na1+3xAlxSn2-xSi2xP3-2xO12. For Na1+3x+yAlxNdyTi2-x-ySi2xP3-2xO12, A.C. impedance measurements indicate that the initial composition with y=0.3, x=0.1 possesses maximum ionic conductivity with 1.80×10-2S/cm at 623K, its activation energy is 38.2 KJ/mol in the temperature range of 473-623K. X-ray powder diffraction analysis shows that a NASICON-type phase exists in the composition range of y=0.3, x ≤ 0.3 and y=0.5, x ≤ 0.2. For Na1+3x+yAlxYyTi2-x-ySi2xP3-2xO12, the initial composition with x=0.1, y=0.3 possesses high ionic conductivity with 1×10-2S/cm at 673K, its activation energy is 55.5 KJ/mol in the temperature range of 473-623K. For Li1+3x+yAlxLayTi2-x-ySi2xP3-2xO12 systems, the initial composition with x=0.1, y=0.4 has the best ionic conductivity with 4.20×10-5S/cm at room temperature , 8.31×10-3S/cm at 673K, its activation energy is19.9KJ/mol in the temperature range of 523-673K. For Na1+3xAlxSn2-xSi2xP3-2xO12, a NaSn2(PO4)3-type solid solution phase with R 3 space group exists in the composition range of x≤0.4, the initial composition with x=0.4 has the best ionic conductivity with 6.91×10-3S/cm at 623K,its activation energy is 50.7KJ/mol in the temperature range of 473-623K. IR spectra analysis shows that most products of the above four systems are stable to water. The previous results indicate that four systems are good sold state electrolytes and it is practical to reformed natural mineral into sold state electrolytes.
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