Effect of He pressure on the superconducting transition temperatures of Na{sub 2}CsC{sub 60} and (NH{sub 3}){sub 4}Na{sub 2}CsC{sub 60}
- Sandia National Labs., Albuquerque, NM (United States)
- AT and T Bell Labs., Murray Hill, NJ (United States)
- Pennsylvania Univ., Philadelphia, PA (United States)
The Na based mixed alkali doped C{sub 60} superconductors show anomalous behavior with respect to the ``universal`` superconducting transition temperature {Tc} vs lattice constant a{sub 0} relation followed by most of the fcc A{sub 3}C{sub 60} superconductors. We have measured dt{sub c}/dP for Na{sub 2}CsC{sub 60} and (NH{sub 3}){sub 4}Na{sub 2}CsC{sub 60} using solid He as the pressure medium to {approximately} 6 kbar finding dT{sub c}/dP equal to {minus}0.8{plus_minus}(0.01) K/kbar and {minus}1.0({plus_minus}0.1)K/kbar for Na{sub 2}CsC{sub 60} and Na{sub 2}(NH{sub 3}){sub 4}C{sub 60} respectively. Our value for Na{sub 2}CsC{sub 60} differs markedly from that obtained by Mizuki et al of about {minus}1.3 K/kbar. However, using N{sub 2} or Ar, we obtain values for dT{sub c}/dP in substantial agreement with Mizuki et al who used fluorinert to generate their pressure. This work emphasizes the need for compressibility measurements with the same pressure medium in the appropriate temperature range so that meaningful comparisons can be made between various pressure measurements and models which are based on lattic spacing.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 10112096
- Report Number(s):
- SAND--94-1703C; CONF-941144--33; ON: DE95006320; BR: GB0103012
- Country of Publication:
- United States
- Language:
- English
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