Solid solution directionally solidified eutectic oxide composites:: Part II.: Co1-xNixO single-crystal growth and characterization

The growth and structure of the Co1-xNixO series of single crystals with 0 less than or equal to x less than or equal to 1 were investigated with the goal of achieving a single-phase crystal over several centimeters of bulk growth. The single crystals were grown via the floating zone method controlling the partial pressure of oxygen to prevent secondary phase precipitation. The resulting crystals were single phase for all compositions. CoO was a single-domain crystal but contained microvoids. The lattice parameters followed a rule-of-mixtures trend, but the coefficient of thermal expansion exhibited a maximum in the middle of the solid solution, which was attributed to enhanced vacancy formation.