Lozenged-shaped crystal

Sodium Chromous Carbonate, NaaCOj.CrCOj.lOHgO, separates as a reddish-brown powder when moist chromous acetate is mixed with a solution of sodium carbonate in an atmosphere of carbon dioxide. It yields microscopic, tabular, lozenge-shaped crystals. If heated at 100° C. in a current of a dry inert gas, the monohydrate, Na3CO3.CrCO3.H2O, is obtained. 

Figure 47. Lozenge-shaped crystals of once-folded alkane CiggLLgg grown from a 0.02% solution in toluene and partially thickened isothermally during annealing at 7 = 73 °C for t= 5 h. Marker = 1 micron (from ref 220b by permission of John Wiley Sons).

Figure 5.3 Transmission electron micrograph of a solution-grown single crystal of linear polyethylene showing lozenge-shaped crystals.

Figure 3.33 AFM image of a polyethylene chair crystal similar to that in Figure 3.13b, but viewed directly from above. Note the right-handed spiral growth on the upper half, and the left-handed spiral on the lower half. A lozenge-shaped crystal with a centrally located spiral growth is on the far right. From Toda et al. [19] with permission from Elsevier.

The fringed mieelle model prevailed for more than a decade until the discovery, in the mid-1950s, that varions polymers eonld eiystallize from solntion to form lozenge-shaped crystals with lateral dimensions several orders of magnitude greater than their thickness [26-29],... 

Fig. 10 Four common types of crystal habit in polyethylene and long alkanes (a) rhombic lozenge bounded by 110 facets (b) lozenge truncated by curved 100 faces (Toda s type B) (c) leaf-shaped crystal bounded solely by curved 100 faces (step propagation rate v equals h = Gno/sin(

Fig. 16 Series of interference contrast optical micrographs of an initially 4.2 wt % solution of n-Ci98H398 in phenyldecane at successive times (indicated) upon reaching Tc = 97.4 °C. The progress of the dilution wave is shown in (b) through (f), triggering the processes of crystallization of needle-like extended-chain crystals and simultaneous dissolution of folded-chain crystals. The needles form along the two 100 faces of the truncated lozenge shaped folded-chain crystals, with a third parallel crystal often appearing in the middle. Bar = 20 pm. (From [44] by permission of American Physical Society)...

Figure 2 A schematic representation of a protein crystal in which the motif (protein molecule) is shown as a spiral in cyan. The smallest unit cell (OPQR) is shown in black it is a rhombus lozenge-shaped with all sides equal. A larger rectangular unit cell (OPCD) is shown in red. This cell leaves one lattice point in the middle and is known as centered.

Fig. 2.15 Several lozenge-shaped polyethylene single crystals grown from xylene solution (from Geil (1963) courtesy of Geil).

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