INTERNAL FRICTION AND ULTRASONIC ATTENUATION RELATED TO CARRIERS IN HIGH Tc SUPERCONDUCTORS

For both BiSrCaCuO and TlBaCaCuO samples, internal frictions (Q^-1) in the kHz range reveal a plateau (Q^-1_p) above T_c and a rapid drop below T_c with the turning points located just at T_c for various samples with different T_c. This anomaly cannot be observed in non-superconducting samples. The ultrasonic attenuation (α) in TlBaCaCuO displays similar results to the internal friction. Moreover, it is discovered that the Q^-1_p is nearly proportional to the carrier density for Y(Pr)BaCuO and Gd(Pr)BaCuO with different Pr contents. These results show that the drop of Q^-1 and a below T_c is closely related to superconducting condensation. The Q^-1_p and α_p can be explained using coupling-model of carriers with local dynamic distortion because high T_c superconductors are strong-correlation systems. Furthermore, by taking account of the smearing of superconducting gap structure resulting from the recombination of quasi-particles and by modifying the BCS relative jump rate as S(E, E', Γ) = Re{1-Δ²/[(E-iΓ)(E'-iΓ)]}, the calculated results of internal friction and ultrasonic attenuation below T_c are in good agreement with the experimental data. The superconducting gap Δ and the damping rate Γ for both BiSrCaCuO and TlBaCaCuO have also been obtained, they are in accordance with those got by tunneling spectrum and NMR methods, etc.     

富氧空气-乙炔火焰原子吸收光谱法测定锶

于试样溶液中加入含有0．5％镧的溶液，在富氧空气－乙炔的条件下，可有效地降低溶质干扰及电离效应，具有较高的原子化效率，可直接用于饮用水与矿泉水中锶的测定。方法的检出限为0．006μg/mL；灵敏度为0．02μg/mL。     

富氧空气-乙炔火焰原子吸收光谱法测定钨

试样在2％磷酸介质中，加入0．5％过硫酸钾，在富氧空气－乙炔火焰的条件下用原子吸收光谱测定钨，可有效地抑制干扰，具有较高的原子化效率，方法的检出限为0．23μg/mL，灵敏度为2．4μg/mL。     

富氧空气-乙炔火焰原子吸收光谱法测定钡

于试样溶液中加入0．25％镧和0．5％氯化钾，在富氧空气－乙炔火焰的条件下，可有效地降低干扰及电离效应，具有较高的原子化效率，方法的检出限为0．001μg/mL，灵敏度为0．12μg/mL，可用于矿泉水中钡的测定。     

INTERNAL FRICTION AND ULTRASONIC ATTENUATION RELATED TO CARRIERS IN HIGH Tc SUPERCONDUCTORS

For both BiSrCaCuO and TlBaCaCuO samples, internal frictions (Q^-1) in the kHz range reveal a plateau (Q^-1_p) above T_c and a rapid drop below T_c with the turning points located just at T_c for various samples with different T_c. This anomaly cannot be observed in non-superconducting samples. The ultrasonic attenuation (α) in TlBaCaCuO displays similar results to the internal friction. Moreover, it is discovered that the Q^-1_p is nearly proportional to the carrier density for Y(Pr)BaCuO and Gd(Pr)BaCuO with different Pr contents. These results show that the drop of Q^-1 and a below T_c is closely related to superconducting condensation. The Q^-1_p and α_p can be explained using coupling-model of carriers with local dynamic distortion because high T_c superconductors are strong-correlation systems. Furthermore, by taking account of the smearing of superconducting gap structure resulting from the recombination of quasi-particles and by modifying the BCS relative jump rate as S(E, E', Γ) = Re{1-Δ²/[(E-iΓ)(E'-iΓ)]}, the calculated results of internal friction and ultrasonic attenuation below T_c are in good agreement with the experimental data. The superconducting gap Δ and the damping rate Γ for both BiSrCaCuO and TlBaCaCuO have also been obtained, they are in accordance with those got by tunneling spectrum and NMR methods, etc.