The orthorhombic-hexagonal phase transformation in the system BaCO3-SrCO3to pressures of 7000 bar
✍ Scribed by S. Weinbruch; H. Büttner; M. Rosenhauer
- Publisher
- Springer-Verlag
- Year
- 1992
- Tongue
- English
- Weight
- 807 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0342-1791
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✦ Synopsis
The orthorhombic-hexagonal phase transformation in the system BaCO3-SrCO3 has been investigated to 7000 bar by differential thermal analysis. The pressure dependence of the orthorhombic-hexagonal transformation temperature T~ may be represented by the polynomial Tp = 933.4-443.3 9 XB,CO 3 + 323.7" X~BaCO3 + P" (8.59--2.48" XB,CO~) where XBaCO = mol fraction of witherite, P the pressure in kbar an~ T the temperature in ~ Lattice parameters refined by powder X-ray diffraction measurements of the orthorhombic solid solution can be fitted to a linear relationship Vorthorh.
[~3] = 259.30 + 44.88" X~aCO 3 with no evidence of any excess volume. The experimental transformation temperatures are modeled by assuming a symmetric regular solution and a diffusionless transformation.