For some vacuum tube work, it was desired to establish a reliable and moderately rapid means of differentiation among several related ceramic bodies, mostly among the high aluminas. Matured composition from a crystallographic standpoint was of primary interest; source and batch constituents were sought only as additional information for interpreting results on the matured ware.

Since Al2O3 represented the major crystal phase in most bodies, the indicators of difference were the minor crystal phases. A number of X-ray diffraction techniques were tried, as were machines of different manufacture. Camera studies with powdered samples were generally ineffective. Useful data were obtained using the Geiger tube—goniometer setup with experimentally determined settings for sensitivity, circuit time constant, sweep rate, beam and receivingslitwidths, etc. Fixedposition peak-height counting was much slower, not practically better for peak-height determination, and introduced chances of missing peaks unless they were first determined by scanning and recording, thus further lengthening the analysis time considerably.

Satisfactory results have been obtained on a number of the bodies of interest. Generally, those bodies which are not differentiated by the X-ray technique outlined are not markedly differentiated in the vacuum tube application.