Focused Heat Source for X Ray Diffractometer

Moss, Marvin; Smith, Douglas L.

doi:10.1063/1.1719859

Cited by 4 publications

(1 citation statement)

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“…Copper Ks radiation was used and the sample was heated with a focused heat source [8]. To minimize contamination of the sample, it was in contact only with glass in the sample holder.…”

Section: Methodsmentioning

confidence: 99%

The transitions in phases II–III–IV in high purity ammonium nitrate

Sowell

Karnowsky

Walters

1971

Journal of Thermal Analysis

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The phase changes in high-purity ammonium nitrate were studied by a differential thermal analysis (DTA) apparatus designed for constant heating and cooling rates and continuous cycling for ~,3-gram samples. On the basis of DTA and X-ray diffraction data very consistent behavior is observed. Phase IV--~ IIl transformation on heating in the range 43 ~ to 51 ~ and Phase II---~ IV transformation on cooling in the range 49 ~ to 53 ~ are demonstrated. The III-+ II transition at about 86 ~ is seen with repeated temperature cycling. This repeatable behavior not consistently seen by investigators using other techniques is believed to be due to the high purity material and constant heating and cooling rates.The literature on the thermal behavior of NH~NO3 (ammonium nitrate) is voluminous; and although it extends back for more than 50 years, it still leaves the reader without a statement of the unambiguous phase relations for the material. Each investigator has reported on a special set of conditions, and the reader has the dilemma of deciding whether the anomalies described are related to the special conditions imposed by the experimenter, are the peculiar characteristics of the salt, or are both.The crystalline modification of NH~NO3 are given as follows [1 ]: Phase I cubic 169.6 ~ to 125.2 ~ Phase II tetragonal 125.2 ~ to 84.2 ~ Phase III orthorhombic 84.2 ~ to 32.1 ~ Phase IV orthorhombic 32.1 ~ to -16 ~ Phase V tetragonal below -16 ~ Phase VI above 160 ~ at pressure >9000 kg/cm ~ Phase VII below -170 ~The fusion temperature and the 125.2 ~ temperature inflections are unambiguous, and Phases VI and VII are not in the scope of this paper. The behavior of the material at 32 ~ and 85 ~ appears to be irregular.

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“…Copper Ks radiation was used and the sample was heated with a focused heat source [8]. To minimize contamination of the sample, it was in contact only with glass in the sample holder.…”

Section: Methodsmentioning

confidence: 99%