Fig. 3. Triple-exposure view of melted single crystal of MgO.In two melting experiments, the temperature of the crystal was observed to be 85°C. higher than that measured in the graphite cylinder, the difference being attributed to reflection by the crystal of the radiation from the susceptor wall. Blackbody conditions were assumed for the cylinder measurements, and it is these values that are reported. Corrected temperatures for the melting point of MgO obtained in separate experiments were 2824" and 2829°C. Thus, a melting point of 2825" f 20°C. is indicated for MgO. The agreement of In a1Structure in the System ZnO-Ti02 8 J. lition to the well-known zinc orthotitanateFormation of the latter compound appe (Zn?Ti04) and zinc metatitanate (ZnTi03), the study of solid-state reactions in the system ZnO-Ti02 disclosed a previously unrecognized compound, ZngTi30~. This compound was obtained when sulfate-containing hydrous titanium oxide of anatase structure was reacted with ZnO at 700" to 900°C. It crystallized in a defect spinel structure with eight Zn2+ ions occupying the tetrahedral positions and twelve Ti4+ ions distributed in sixteen octahedral positions (a, = 8.395 f 0.002 a.u.). Crystallographic data are given for zinc orthotitanate and metatitanate.. in red to be favored by rutile TiOz sources and those readily convertible to rutile under the reaction conditions.

2157bond can be formed in the latter two cases due to the separation of the hydrogen bonding atoms. As the data in this work show, the spectra can be explained in terms of the dipolar species existing in DzO.In summary, by assuming the dipolar form for the three acids as the principal species in aqueous solution, a variety of solution infrared results can be explained.It has previously been proposed that I represented picolinic acid in D20.4 Internal hydrogen bonding of Acknowledgment.The solubility of A1203 in rutile Ti02 was determined in the temperature region of 1200-1426' from the change of the c unit-cell parameter. Solubility increased with equilibration temperature, ranging from 0.62% A1203 by weight at 1200' to 1.97% at 1426'. Corundum was the equilibrium solute phase below, and AlzTiOs above, 1240'. The density of a rutile sample equilibrated at 1426' containing 1.6% by weight A1203 was 4.199 g/cma, not significantly different from 4.202 g/cm3 measured for a corresponding pure rutile sample. These results are consistent with an interstitial solubility model in which AIS+ and 02-in 1 : 2 proportion are placed on the respective rutile lattice sites, and the remaining A13+ occupies interstitial spaces. Treatment of the temperature dependence of the solubility data gave values for AH' of solution of 35 kcal/mol and 100 kcal/mol for A12Ti05 and AlzOs, respectively. The heat of formation of AlzTiOs computed from these results is -559 kcal/mol near the transition temperature.Solubility also increased with the addition of NblOS.

Characterization of platiness of kaolin pigments was derived from the divergence of measurements of their particle size distribution by two different techniques: sedimentation and light scattering. A numerical shape factor, which is related to the ratio of kaolin particle face diameter to its thickness, can be calculated to provide a quantitative measure of such platiness. Two sets of kaolin pigments were prepared from a Middle Georgia kaolin: delaminated and non-delaminated. Shape factors of delaminated samples were higher than those of non-delaminated ones. Maximum platiness was found between equivalent volume diameters of 1·0 and 2·0 μm. Examples are presented where properties of coated paper are correlated with the size and shape of kaolin pigments.

His research activities include light scattering by pigments, solid state reactions, fluid energy milling, and various other facets of titanium pigment technology. He is a member of the American Association for the Advancement of Science, the American Chemical Society, and Tau Beta Pi.

No abstract