T–P phase diagram of ammonia solid phases I, II and III

2005

J. Phys. Chem. B

Self Cite

We correlate here the thermal expansivity alphap to the frequency shifts 1/nu(partial differential nu/partial differential P)T for the rotatory lattice (librational) mode in ammonia solid I close to the melting point. This is carried out for the pressures of 0, 1.93, and 3.07 kbar at various temperatures for this solid structure. By obtaining linear plots of alphap versus 1/nu(partial differential nu/partial differential P)T for the pressures studied, we extract the values of the slope dPm/dT according to our spectroscopic relation. Our calculated values of dPm/dT can be compared with the experimental ones for ammonia solid I close to the melting point.

Section: Introductionsupporting

confidence: 71%

Raman Frequency Shifts for the Rotatory Lattice Mode Close to the Melting Point in Ammonia Solid I

Karaçalı

2005

J. Phys. Chem. B

Self Cite

“…Melting curves of ammonia solid I (T m =192.5 K, P=0) and solid II (T m =222.4 K, P m =3.07 kbar) have been calculated by using the mean field theory in our previous study [5]. We have also calculated a T-P phase diagram of ammonia including the solid phases I, II and III by the mean field theory [6].…”

Section: Introductionmentioning

confidence: 99%

“…(4)(5)(6) for constant temperatures of 254.6, 274 and 297.5 K, respectively, in ammonia solid III. This linear variation of α p with the κ T which follow power laws (Eqs.…”

mentioning

confidence: 99%

A linear variation of the thermal expansivity with the isothermal compressibility for ammonia solid III near the melting point

Caglar

2010

Korean J. Chem. Eng.

The thermal expansivity α p is related to isothermal compressibility κ T at various pressures for constant temperatures of 254.6, 274 and 297.5 K close to the melting pressure in ammonia solid III. By analyzing the experimental data for κ T according to a power-law formula, a linear variation of α p with the κ T is established here close to the solid-liquid transition in ammonia. Anomalous behavior of thermal expansivity α p and the isothermal compressibility κ T near the melting pressure is indicative of the λ-type transition in ammonia solid III.

“…We have also calculated P-T phase diagram of solid I and II with the melting curves in ammonia [14] and T-P phase diagram of solid I, II and III phases [15] using the mean field theory. The experimental P-T phase diagram of ammonia [5,8], as given in Fig.…”

Section: Introductionmentioning

confidence: 99%

Critical behaviour of the specific heat and the thermal expansion close to the melting point in ammonia solid III

Caglar

2009

Per. Pol. Chem. Eng.

A linear correlation between the specific heat C P and the thermal expansion α p is established here for constant temperatures close to the melting pressure in ammonia solid III. For this correlation, the experimental data for the isothermal compressibility κ T is analysed according to a power-law formula with the critical exponent γ and, the C P and α p are calculated as a function of pressure near the melting point in ammonia solid III.Values of the entropy changes with the temperature, which are extracted from linear plots of C P against α p , decrease as the temperature increases for the ammonia solid III prior to melting.