Differential osmotic pressure measurements of the concentration susceptibility of liquid /sup 3/He//sup 4/He mixtures near the lambda curve and tricritical point
Values of the concentration susceptibility (partial x/partial ..delta..)/sub T/,P of liquid /sup 3/He//sup 4/He mixtures have been determined near the lambda curve and tricritical point from measurements of the differential osmotic pressure as a function of temperature T at four values of the /sup 3/He mole fraction, x = 0.594, x = 0.644, x = 0.680, and x = 0.706. Here ..delta.. = ..mu../sub 3/ - ..mu../sub 4/ is the difference between molar chemical potentials and P is the pressure. Our results for the two values of x less than the tricritical value x/sub t/ = 0.675 show pronounced peaks at the lambda transition. For 3 x 10/sup -4/ < or approx. = vertical-bar t vertical-bar < or approx. = 10/sup -2/, where t equals (T - T/sub lambda/(x))/T/sub lambda/(x), these peaks may be characterized both above and below the transition by the form (A/sub plus-or-minus//..cap alpha../sub plus-or-minus/) (vertical-bart vertical-bar/sup -alpha/ +- - 1) + B/sub plus-or-minus/, with exponents ..cap alpha../sub plus-or-minus/ lying in the range from approx. 0.0 to approx. 0.2. Except perhaps for x < x/sub t/ in the normal-fluid region away from the lambda transition, our data appear to be consistent with a simple tricritical scaling relationship of the form (partialx/partial..delta..)/sub T/,P = f (x) ..xi../sup -1/ (T-T/sub t//T/sub t/)/vertical-barx-x/sub t//x/sub t/vertical-bar), where f and ..xi.. are functions determined by experiment and T/sub t/ = 0.867 K is the tricritical value of T. With the aid of this scaling relationship, the behavior of (partialx/partial..delta..)/sub T/,P along curves of constant ..delta.. near the lambda curve has been constucted from our data at constant x.
- Research Organization:
- Tate Laboratory of Physics, University of Minnesota, Minneapolis, Minnesota 55455
- OSTI ID:
- 6352022
- Journal Information:
- Phys. Rev., Sect. B. Condens. Matter; (United States), Vol. 19:5
- Country of Publication:
- United States
- Language:
- English
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640450* - Fluid Physics- Superfluidity