Donnay

In the late 1960s El Goresy and Donnay [17] discovered a new form of carbon which they called white carbon or Chaoite in a carbon-rich gneiss in the Ries meteorite crater in Bavaria. Chaoite has an hexagonal crystal stmcture and it... 

Docherty, R., Clydesdale, G., Roberts, K.J. and Bennema, P., 1991. Application of the Bravais-Freidel-Donnay-Harker attachment energy and Ising models to predicting and understanding the morphology of molecular crystals. Journal of Physics D Applied Physics, 24, 89-99. 

The symmetry of magnetic crystals has been discussed by several authors. See for example L. D. Landau, and E. M. Lifshitz, Electrodynamics of Continuous Media, Addison-Wesley Publishing Company, Reading, Mass., 1960 B. A. Tavger and J. M. Zaitzev, Soviet Phys.—JETP, 3, 430 (1956) Y. LeCorre, J. phys. radium, 19, 750 (1958) G. Donnay, et aZ., Phys. Bev., 112,1917 (1958). 

Albert Donnay, President of Board of Directors 508 Westgate Rd. 

Donnay G. (1969). Further use for the Pauling-bond concept. Carnegie Inst. Wash. Yb., 68 292-295. 

Le Page Y. and Donnay G. (1976). Refinement of the crystal structure of low-quartz. Acta Cryst, B32 2456-2459. 

Combination of the above principles led Donnay (1969) and Donnay and Allmann (1970) to propose a generalized scheme for variation of bond length with bond strength in mixed bonds (not purely ionic or purely covalent). The equation proposed by the above authors is... 

Figure 1.10 shows the relationship between bond strength and degree of covalence in cation-oxygen bonds for cations with 18, 36, and 54 electrons (note that in table 1.9 the parameters of equation 1.48 are identical for the three isoelectronic series). By combining equation 1.48 with a modified form of Donnay s (1969) equation ... 

A simple correlation was noticed by Donnay and Harker, (10) between the interplanar spacing of a crystallographic plane, d, and its area on an average crystal. A similar correlation holds between d and the frequency with which the plane (hkl) appears in an ensemble of crystals. Since an area of a plane is roughly proportional to the inverse of its (linear) growth velocity R, the Donnay-Harker law is equivalent to stating that R 1/dj. 

Blesa, M. (1994) Morphological properties of a-FeOOH, y-FeOOH and Fej04 obtained by oxidation of aqueous Fe(II) solutions. J. Colloid Interface Sd. 165 244-252 Dong, H. Fredrickson, J.K. Kennedy, D.W. Za-chara, J.M. Kukkadapu, R.K. Onstott,T.C. (2000) Mineral transformations associated with the microbial reduction of magnetite. Chem. Geol. 169 299-318 Donnay J.D.H. Marker, D. (1935) A new law... 

Yoon, R.H. Salman,T. Donnay, G. (1979) Predicting points of zero charge of oxides and hydroxides. J. Colloid Interface Sd. 70 483-493... 

Figure 4.2. The morphology of quartz crystal predicted by (a) the Bravais empirical law and (b) Donnay-Harker s law.

If the positions of the H ions are not known, one can make use of the observed distances between the donor and acceptor anions to search for potential hydrogen bonds. Donnay and Allmann (1970) have shown that it is possible to identify which atoms are donors and which are acceptors by considering the deficiency in the bond valence sums when the contributions of the hydrogen bonds are ignored. Donor anions will have a deficiency of around 0.8 vu while those with a smaller deficiency are likely acceptors. Identifying neighbouring donor and acceptor anions usually allows the hydrogen bond... 

J. Donnay and H. Ondik, CvystalData Determinative Tables, Vol. 2,3rd ed., U.S. Dept, of Commerce, National Bureau of Standards, Joint Committee on Powder Standards, Washington, D.C., 1975, pp. 1—202. 

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