Energy-dispersive and angle-dispersive x-ray-diffraction (EDXD and ADXD) measurements show that when compressed by pressures above 10.0 GPa isostructural Pb(Formula presented), Ba(Formula presented), and Sr(Formula presented) transform reversibly to highly disordered structures. Raman measurements under compression suggest that the transformation occurs via reorientation of the nitrate ions to multiple sites and movement of the metal ions from the crystal positions. Our main conclusion is that EDXD and ADXD measurements give different meanings to the notion "x-ray amorphous." Thus, whenever this phrase is used, the method used and the conditions that prevail must be specified. We also suggest that our results show that Raman spectroscopy can be used to distinguish nonrandom nitrate and cation environments in metal nitrate glasses.
|Original language||English (US)|
|Number of pages||8|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jan 1 1996|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics