Phase Transitions and Water Dynamics of [Co(H2O)6](ClO4)2 and [Mn(H2O)6](BF4)2 Studied by Neutron Scattering Methods

2001 ◽  
Vol 56 (3-4) ◽  
pp. 244-248 ◽  
Author(s):  
E. Mikuli ◽  
A. Migdał-Mikuli ◽  
I. Natkaniec ◽  
B. Grad
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Phase Transitions ◽  
Neutron Scattering ◽  
Powder Diffraction ◽  
Neutron Powder Diffraction ◽  
Water Dynamics ◽  
Incoherent Neutron Scattering ◽  
Solid Phases ◽  
Incoherent Neutron

Abstract Inelastic incoherent neutron scattering (IINS) spectra and neutron powder diffraction (NPD) patterns, registered for [Co(H2O)6](ClO4)2 at 18 -270 K and for [Mn(H2O)6](BF4)2 at 18 -230 K, provided evidence that these crystals possess three solid phases in these ranges of temperatures. In both compounds the phase transition occurring at TC3 is connected with a change of the crystal structure, and that occurring at TC2 with a change in the rate of the reorientational motions of H2O ligands.

Mn-Mg disordering in cummingtonite: a high-temperature neutron powder diffraction study

2000 ◽  
Vol 64 (2) ◽  
pp. 255-266 ◽  
Author(s):  
J. J. Reece ◽  
S. A. T. Redfern ◽  
M. D. Welch ◽  
C. M. B. Henderson
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
New York ◽  
High Temperature ◽  
Powder Diffraction ◽  
Elevated Temperatures ◽  
Neutron Powder Diffraction ◽  
Site Preference ◽  
A Site

AbstractThe crystal structure of a manganoan cummingtonite, composition [M4](Na0.13Ca0.41Mg0.46Mn1.00) [M1,2,3](Mg4.87Mn0.13)(Si8O22)(OH)2, (Z = 2), a = 9.5539(2) Å, b = 18.0293(3) Å, c = 5.2999(1) Å, β = 102.614(2)° from Talcville, New York, has been refined at high temperature using in situ neutron powder diffraction. The P21/m to C2/m phase transition, observed as spontaneous strains +ε1 = −ε2, occurs at ˜107°C. Long-range disordering between Mg2+ and Mn2+ on the M(4) and M(2) sites occurs above 550°C. Mn2+ occupies the M(4) and M(2) sites preferring M(4) with a site-preference energy of 24.6±1.5 kJ mol−1. Disordering induces an increase in XMnM2 and decrease in XMnM4 at elevated temperatures. Upon cooling, the ordered states of cation occupancy are ‘frozen in’ and strains in lattice parameters are maintained, suggesting that re-equilibration during cooling has not taken place.

Phase Transitions and Water Dynamics of [Mn(H2O)6](ClO4 )2 Studied by Differential Scanning Calorimetry and Neutron Scattering Methods

2000 ◽  
Vol 55 (9-10) ◽  
pp. 759-764 ◽  
Author(s):  
E. Mikuli ◽  
A. Migdał-Mikuli ◽  
I. Natkaniec ◽  
J. Mayer
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Neutron Scattering ◽  
Structural Phase Transition ◽  
Room Temperature ◽  
Structural Phase ◽  
Water Dynamics ◽  
Water Molecules ◽  
Temperature Phase ◽  
Solid Phases

Abstract DSC measurements performed at 95 -290 K have shown that [Mn(H 2 O) 6 ](CIO 4) 2 possesses, besides a high-temperature phase, existing above 323 K, four low-temperature solid phases. The inelastic incoherent neutron scattering (IINS) spectra and neutron powder diffraction (NPD) pat-terns registered at 20 -290 K have supported the DSC results and provided evidence that the investigated substance possesses even more than five solid phases. The IINS spectra have shown that in the room-temperature phase, water molecules perform fast stochastic reorientation at the picosecond scale. The orientational disorder characteristic for the room-temperature phase can be easily overcooled and frozen. Even by relatively slow cooling at ca. 40 K/hour a metastable, orientational (protonic) glass phase is formed below ca. 160 K. Below ca. 100 K, a structural phase transition was observed by the NPD, however the IINS spectra indicate existence of the pure ordered low-temperature phase only after annealing the sample for a few hours at 100 K. On heating, a structural phase transition takes place at ca. 120 K, and at ca. 225 K water molecules begin fast reorientation.

Phase transitions and NH3 motions in [Zn(NH3)4](ClO4)2 studied by incoherent neutron scattering and 1H NMR methods

2007 ◽  
Vol 335 (2-3) ◽  
pp. 187-193 ◽  
Author(s):  
Anna Migdał-Mikuli ◽  
Krystyna Hołderna-Natkaniec ◽  
Edward Mikuli ◽  
Łukasz Hetmańczyk ◽  
Ireneusz Natkaniec
Keyword(s):  
Phase Transitions ◽  
Neutron Scattering ◽  
1H Nmr ◽  
Incoherent Neutron Scattering ◽  
Nmr Methods ◽  
Incoherent Neutron

Incoherent neutron scattering around displacive incommensurate structural phase transitions

1992 ◽  
Vol 180-181 ◽  
pp. 342-344 ◽  
Author(s):  
J. Etrillard ◽  
B. Toudic ◽  
H. Cailleau ◽  
M.H. Lemée-Cailleau ◽  
G. Coddens ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Neutron Scattering ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Incoherent Neutron Scattering ◽  
Incoherent Neutron

Neutron Scattering in 3,3-Dimethyl-2-Butanol and 2,3-Dimethyl-2-Butanol

2006 ◽  
Vol 112 ◽  
pp. 89-92 ◽  
Author(s):  
Ewa Juszyńska ◽  
M. Massalska-Arodź ◽  
J. Mayer ◽  
Ireneusz Natkaniec ◽  
J. Krawczyk ◽  
...  
Keyword(s):  
Solid State ◽  
Neutron Scattering ◽  
Boson Peak ◽  
Plastic Crystal ◽  
Incoherent Neutron Scattering ◽  
Group Position ◽  
Solid Phases ◽  
Incoherent Neutron

Influence of the OH group position in the molecule on solid state polymorphism was found. Dynamics in solid phases of two dimethyl butanols were studied by inelastic incoherent neutron scattering. In glass of plastic crystal the boson peak was detected.

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