Study of the Crystal Structure and Phase Transition of Li2NH System

2008 ◽  
Vol 1098 ◽  
Author(s):  
Jinbo Yang ◽  
J. Lamsal ◽  
Q Cai ◽  
W B Yelon ◽  
W J James
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Temperature ◽  
High Temperature Phase ◽  
Synthesis Methods ◽  
Temperature Phase ◽  
Hydrogen Storage Capacity ◽  
Structural Differences ◽  
Different Temperatures ◽  
Low Temperature Phase

AbstractNeutron diffraction at different temperatures has been used to study the crystal structure and possible phase transitions of Li2NH. It was found that the crystal structure and phase transition are related to the synthesis methods. A phase transition from the low temperature phase 16-350 K to the high temperature phase above 370 K has been confirmed for the ケ-Li2NH sample prepared by reacting Li3N with LiNH2. The Li2NH (β-Li2NH) prepared by decomposition of LiNH2 shows only the high temperature phase. The reaction of LiH+LiNH2 at 300°C for 12 h under vacuum produces some Li2NH (γ-Li2NH) with partially unreacted LiNH2 and LiH as impurities. There is no phase transition in the temperature range from 16 K to 400 K for the - and β-Li2NH phases.ケ-Li2NH exhibits a higher reversible hydrogen storage capacity and faster kinetics. The structural differences among the lithium imides may lead to different reaction mechanisms for hydrogen absorption/desorption in the Li-N-H system.

scholarly journals A jumping crystal predicted with molecular dynamics and analysed with TLS refinement against powder diffraction data

IUCrJ ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 136-144 ◽  
Author(s):  
Jacco van de Streek ◽  
Edith Alig ◽  
Simon Parsons ◽  
Liana Vella-Zarb
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Molecular Dynamics ◽  
High Temperature ◽  
Md Simulations ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Powder Diffraction Data ◽  
Transition Mechanism ◽  
Low Temperature Phase

By running a temperature series of molecular dynamics (MD) simulations starting from the known low-temperature phase, the experimentally observed phase transition in a `jumping crystal' was captured, thereby providing a prediction of the unknown crystal structure of the high-temperature phase and clarifying the phase-transition mechanism. The phase transition is accompanied by a discontinuity in two of the unit-cell parameters. The structure of the high-temperature phase is very similar to that of the low-temperature phase. The anisotropic displacement parameters calculated from the MD simulations readily identified libration as the driving force behind the phase transition. Both the predicted crystal structure and the phase-transition mechanism were verified experimentally using TLS (translation, libration, screw) refinement against X-ray powder diffraction data.

On the Phase Transition of Bis(pyridinium)hexachlorometallates, (C5H5NH)2[MCl6], M = Sn, Te, Pb, Pt. An X-Ray and 35Cl NQR Study

1987 ◽  
Vol 42 (7) ◽  
pp. 739-748 ◽  
Author(s):  
Dirk Borchers ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Phase Ii ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray ◽  
Lattice Constants ◽  
Pyridinium Ring ◽  
35Cl Nqr ◽  
Low Temperature Phase

A phase transition has been observed in bis(pyridinium) hexachlorometallates (C5H5NH)2[MIVCl6]. M = Sn. Te. Pb. Pt. The crystal structure of the low temperature phase II of the salt with M = Sn was determined, space group C 1ḷ- P 1̅, Z = 1 (a = 734.1pm, b = 799.0 pm, c = 799.7 pm,α= 83.229°. β = 65.377°, γ= 84.387°, T = 297 K). The four compounds are isotypic in phase II as well as in the high temperature phase I (C2H2-B2 /m, Z = 2) for which the crystal structure is known for M = Te . The lattice constants of all compounds (both phases) are given. The temperature dependence of the 35Cl NQR spectrum was investigated. The three line 35Cl NQR spectrum is in agreement with the crystal structure. The dynamics of the pyridinium ring shows up in a fade out of part of the 35Cl NQR spectrum . The influence o f H ↔ D exchange on 35Cl NQR is studied and an assignment of ν (35Cl) ↔ Cl(i) is proposed. The nature of the phase transition P1̅ (Z = 1) ↔ B2 /m (Z = 2) is discussed.

Formation of the high temperature phase in vacuum deposited SnSe thin films

1986 ◽  
Vol 175 (1-2) ◽  
Author(s):  
T. Subba Rao ◽  
B. K. Samantaray ◽  
A. K. Chaudhuri
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Glass Substrates ◽  
Different Temperatures ◽  
Substrate Temperatures ◽  
Low Temperature Phase

AbstractThin films of SnSe vacuum deposited on glass substrates kept at different temperatures have been studied by X-ray diffraction. It is observed that the high temperature phase of SnSe, usually found above 807 K is frozen in along with the low temperature phase when deposited at substrate temperatures of 473 K and above.

Topological polymorphism and temperature-driven topotactic transitions of metal–organic coordination polymers

CrystEngComm ◽  
2020 ◽  
Vol 22 (38) ◽  
pp. 6295-6301
Author(s):  
Vadim A. Dubskikh ◽  
Anna A. Lysova ◽  
Denis G. Samsonenko ◽  
Danil N. Dybtsev ◽  
Vladimir P. Fedin
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Solid State ◽  
Low Temperature ◽  
High Temperature Phase ◽  
Phase Changes ◽  
Organic Ligands ◽  
Temperature Phase ◽  
Metal Organic ◽  
Low Temperature Phase

A facile crystal-to-crystal solid-state phase transition between a low-temperature phase and a high temperature phase changes the MOF topology and involves a significant rearrangement of bulky organic ligands.

Synthesis, Crystal Structure, and High-Temperature Phase Transition of the Novel Plumbide Na2MgPb

2014 ◽  
Vol 53 (10) ◽  
pp. 5253-5259 ◽  
Author(s):  
Takahiro Yamada ◽  
Takuji Ikeda ◽  
Ralf P. Stoffel ◽  
Volker L. Deringer ◽  
Richard Dronskowski ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
The Novel ◽  
Temperature Phase Transition
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