Introduction: The Martian meteorite whole rock Rb-Sr isotopic compositions and the initial Pb data from plagioclase separates suggest strongly that the crust of their parent body originated from an ancient planetary global differentiation process about 4.5 Ga ago. The absence of plate tectonic activity on early Mars excludes a crustal recycling and preserves the isotopic systems derived from th...

An ion-exchange process was developed for the separation of spectrographically pure praseodymium salts in kilogram amounts from commercially available concentrates. The application of either 0.5% or 0.1% citrate solutions as eluting agents was show to result in excellent separations of praseodymium from samarium, neodymium, and lanthanum when the mixed rare earths were eluted from Amberlite IR-...

Spectrographic methods applicable to the determination of major rare earth constituents in complex mixtures are described. The specific examples discussed are the determination of yttrium and gadolinium in the concentration range of 10 to 100 per cent. The procedures involve the high current DC arc excitation of rare earth oxide sample-ceric oxide-graphite mixtures. Selected lines of cerium are...

This paper reviews our recent experimental work on erbium incorporated into gallium arsenide during MBE growth. The electrical behaviour of the erbium is considered in relation to its interaction with intentionally added dopants (silicon, selenium and berylium) and the effect of the erbium on the deep state population is discussed. At higher concentrations the morphology of phase separation is ...

A volcanic crust may be produced as a result of magma ocean processes. Solidification of a magma ocean naturally produces a silicate mantle with denser layers near the surface, therefore unstable to gravitational overturn. The mantle is predicted to rapidly flow in the solid state to gravitational stability. Hot buoyant silicate mantle rising from depth will melt through depressurization and er...

Nucleosynthesis, on the surface of accreting neutron stars, produces a range of chemical elements. We perform molecular dynamics simulations of crystallization to see how this complex composition forms new neutron star crust. We find chemical separation, with the liquid ocean phase greatly enriched in low atomic number elements compared to the solid crust. This phase separation should change ma...