Observation of Nonlinear and Nonequilibrim Phenomena in Samarium Nitrate Crystal

Kawashima, Riki; Matsuda, Takeyoshi

doi:10.1143/jpsj.58.3435

Cited by 16 publications

(11 citation statements)

References 5 publications

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“…5 and 9 K on deuteration, respectively. Although another anomaly of the dielectric constant has been reported around 283 K, − the heat anomaly was not detected in the present DTA investigation. The shift of the transition temperature was not observed on repeating runs.…”

Section: Resultscontrasting

confidence: 62%

“…The DTA measurement was repeated between 140 and 330 K. Two heat anomalies were detected at 192 and 245 K in the heating process. In the cooling process, heat anomalies were detected at 229 and 181 K. The anomalies at 245 K in heating and 229 K in cooling are considered to correspond to the phase II−III transition observed by the dielectric constant and DTA for the protonated compound. − , The anomalies at 192 K in heating and 181 K in cooling are considered to correspond to the phase III−IV transition observed by DTA for the protonated compound . The phase II−III and III−IV transition points shifted to high temperature by ca.…”

Section: Resultsmentioning

confidence: 99%

“…283 to 228 K and is known to be unstable. The temperature variation of the dielectric constant is accompanied by the large thermal hysteresis and is not reproducible in phase II. − These phenomena are different from the usual phase transition. Kawashima et al have attempted to analyze the instability of phase II at the nonlinear and nonequilibrium properties. − However, the origin of the instability is not elucidated and it is interesting to study the static and the dynamic structure of this crystal.…”

Section: Introductionmentioning

confidence: 96%

“…The temperature variation of the dielectric constant is accompanied by the large thermal hysteresis and is not reproducible in phase II. − These phenomena are different from the usual phase transition. Kawashima et al have attempted to analyze the instability of phase II at the nonlinear and nonequilibrium properties. − However, the origin of the instability is not elucidated and it is interesting to study the static and the dynamic structure of this crystal. The symmetry of Sm(NO 3 ) 3 ·6H 2 O is triclinic and the space group is P 1̄ at room temperature. , For six water molecules, four coordinated waters are directly coordinated to the metal, whereas two crystallization waters do not.…”

Section: Introductionmentioning

confidence: 96%

“…Recently, the unstable phenomena of the electric and the magnetic properties have been reported for the several rare-earth nitrate crystals. − Samarium nitrate hexahydrate, Sm(NO 3 ) 3 ·6H 2 O, has been reported to have four phases. − , In these phases, phase II exists in the temperature range from ca. 283 to 228 K and is known to be unstable.…”

Section: Introductionmentioning

confidence: 99%

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Deuterium NMR Study of Unstable Phenomena and Water Molecular Dynamics in Samarium Nitrate Hexahydrate Crystal

et al. 1999

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Deuterium NMR spectra, spin-lattice relaxation time T 1 , and differential thermal analysis (DTA) were measured for Sm(NO 3 ) 3 ‚6D 2 O. The magnetization recovery can be divided into two components. From deuterium NMR spectra and T 1 , the short and the long components of T 1 were found to be mainly dominated by the 180°flip of the crystallization and the coordinated water molecules, respectively. For the nonannealed sample, the reproducibility of T 1 was observed. The influence of the instability was not seen in the long component of T 1 . The results of the long component of T 1 gave the activation energy E a ) 20 kJ mol -1 and the correlation time at infinite temperature τ c0 ) 7.8 × 10 -12 s for the 180°flip of the coordinated water molecule. The motion of the crystallization water at low temperatures can be explained by the 180°flip in the asymmetric double minimum potential. τ c0 ) 1.2 × 10 -12 s, E a ) 16 kJ mol -1 , and the energy difference in the potential wells ∆E ) 2.0 kJ mol -1 were obtained for the 180°flip of the crystallization water from the short component of T 1 . The potential wells for the 180°flip of the crystallization water changed gradually in phase II and approached the symmetric wells with increasing temperature. For the annealed sample, the drastic change of T 1 was observed in phases II and III. Both the long and the short components of T 1 did not show the reproducibility. These unstable phenomena are interpreted in terms of the metastable state due to the change of the hydrogen bond between the crystallization and the coordinated waters by annealing.

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