The resistivity of calcium, strontium and barium under pressure

Abstract

The variation of the resistivity of Ca, Sr, Ba with volume is discussed on the basis of recent band structure calculations. The calculated resistivity p in the f.c.c. phase rises with decreasing volume Ω, until a semi-metallic region is reached characterized by high resistivity and small negative or positive ∂_p/∂T at room temperature. The b.c.c. phase is expected to remain a reasonably good metal with a maximum ρ at some critical Ωc. Qualitative agreement with the observed variation of ρ with P and T is found for Sr. In Ca the structure at high pressure is not known, and on the basis of the electrical behaviour and other evidence it is suggested that it may remain in the f.c.c. structure, or a distorted f.c.c. up to 400 kbar. The electrical properties at higher pressure would be consistent with a b.c.c. structure. In Ba one of the high pressure phases, previously described as probably f.c.c. from x-ray evidence, has electrical properties consistent with the f.c.c. structure.