Determination of lattice constants, and thermal expansion coefficients of Ti₂O₃ and of its solid solutions with Ti

For the determination of the precise lattice constants of Ti₂O₃, it is very important to use a Ti₂O₃ as pure as possible. Due to the formation of solid solution with titanium or oxygen, ranging from 32.5 to. 34.5% O₂ by weight in the Ti-O binary system, it is very difficult to get a pure Ti₂O₃ (33.8% O₂ by weight) in the laboratory. To determine the precise lattice constants of pure Ti₂O₃, therefore, the extrapolation method was used. This method computes the respective constants for pure Ti₂O₃ from the values obtained With Ti₂O₃-Ti solid solutions by extrapolation. To carry out such an investigation on Ti₂O₃ the determinations as the following had to be made: 1) Determination of the exact lattice parameters of a substance having a composition close to Ti₂O₃. 2) Determination of the coefficients of thermal expansion (linear and volume expansion coefficients of the hexagonal and the rhombohedral unit cell, expansion coefficient of the axial ratio of the hexagonal unit cell, and interaxial angle expansion coefficient of the rhombohedral unit cell.) 3) Establishment of the change of the same parameters with small change in composition of the Ti₂O₃ -Ti solid solution. 4) Determination of the experimental densities and the molecular weights of Ti₂O₃-Ti solid solutions. These determinations would allow one: 5) To make conclusions concerning the perfection of Ti₂O₃-Ti solid solution and 6) To determine the parameters of pure Ti₂O₃. For the evaluation of soundness of the crystal lattice of Ti₂O₃, experimental macroscopic densities of the samples used had to be determined --Introduction, pages 1-2