The solutions, which contained from 1 to 2.5 hydroxide ions added per aluminum ion, were studied immediately after preparation and also in the final equilibrium condition. Aggregates present in the freshly prepared solutions probably have a characteristic platelet shape. Mention is made of the possible importance of these platelet-shaped aggregates to the structure of freshly precipitated aluminum hydroxide gel. Estimates of the size of the clusters present in the aged solutions were obtained in terms of the radius-of-gyration parameter. For solutions with OH/Al ion ratios between 1.5 and 2.25, the parameter had a constant value of 4.3 Å. This value is in good agreement with the calculated radius of gyration for the complex [Al13O4(OH)24(H2O)12]7+.
The digit current margins of a DRO magnetic film memory are determined by the disturb and writing or restoring thresholds. In an actual memory these thresholds will vary with both the film parameters and the drive line configuration. The effect of the magnetic parameters of the storage elements on these thresholds is determined by measuring the digit current margins of storage element arrays of varied magnetic parameters in a test apparatus simulating the memory operations and drive line configuration. A figure of merit calculated from these margin measurements is introduced and is used to determine the optimum film parameter values. To illustrate the effectiveness of the technique, data obtained during the experimental determination of optimum array coercivity are presented and the resultant figure of merit is discussed. Results indicate that array coercivities of 2.5 to 2.6 Oe yield maximum digit current margins. Interpretation of results of restore current measurements in terms of skew and dispersion currents is also presented.
The object of this study is to obtain film storage elements exhibiting the expanded digit current margins required for improved storage element densities while maintaining the nominal drive current amplitudes. Copper films varying in thickness from 200 to 50 000 Å were deposited on conventional film elements at substrate temperatures, during copper deposition, of 190° to 330°C. Increases in element coercive force of up to 75% can be attained without significantly changing other basic magnetic properties of the elements. The disturb threshold of the elements can also be increased by nearly 75% with the write thresholds increasing only 10% to 15%. Average digit current margins of the copper-coated elements are consistently greater than the margins of the comparable uncoated Permalloy control elements with the same nominal drive currents. Worst-case margin comparisons of coated and uncoated arrays indicate no appreciable change in the uniformity of element switching properties. Irreversible and reversible temperature-induced changes in the margins are discussed.
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