TY  - JOUR
AU  - Tuel, Alain
AU  - Caldarelli, Stefano
AU  - Meden, Anton
AU  - McCusker, Lynne B.
AU  - Baerlocher, Christian Baerlocher
AU  - Ristic, Alenka
AU  - Rajić, Nevenka
AU  - Mali, Gregor
AU  - Kaučič, Venčeslav
PY  - 2000
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/6400
AB  - The triclinic form of AlPO4-34, a microporous aluminophosphate with the chabazite (CHA) topology, adopts a rhombohedral symmetry upon calcination. The framework structure of this phase remains intact under ambient conditions, but it distorts dramatically, though reversibly, in the presence of water. Following these structural changes in situ by X-ray diffraction revealed that there are actually two stable rehydrated phases, which differ from each other by one water molecule in the channel. Both of these phases have triclinic unit cells that are closely related to that of the calcined rhombohedral phase. The structure of the low-temperature (10 °C), fully rehydrated phase (phase B) was elucidated by combining high-resolution synchrotron powder diffraction with solid-state NMR techniques. Coordination of three of the six Al atoms to water molecules causes the deformation of the framework and the reduction of the symmetry. Rietveld refinement of the structure of phase B in the triclinic space group P1 (a = 9.026, b = 9.338, c = 9.508 Å, α = 95.1°, β = 104.1°, and γ = 96.6°) converged with RF = 0.079 and RWP = 0.176 (Rexp = 0.087). Framework connectivities derived from the structure were used to assign 31P NMR lines as well as part of the 27Al NMR signal.
PB  - American Chemical Society
T2  - The Journal of Physical Chemistry B
T1  - NMR Characterization and Rietveld Refinement of the Structure of Rehydrated AlPO4-34
EP  - 5705
SP  - 5697
VL  - 104
DO  - 10.1021/jp000455a
ER  - 

@article{
author = "Tuel, Alain and Caldarelli, Stefano and Meden, Anton and McCusker, Lynne B. and Baerlocher, Christian Baerlocher and Ristic, Alenka and Rajić, Nevenka and Mali, Gregor and Kaučič, Venčeslav",
year = "2000",
abstract = "The triclinic form of AlPO4-34, a microporous aluminophosphate with the chabazite (CHA) topology, adopts a rhombohedral symmetry upon calcination. The framework structure of this phase remains intact under ambient conditions, but it distorts dramatically, though reversibly, in the presence of water. Following these structural changes in situ by X-ray diffraction revealed that there are actually two stable rehydrated phases, which differ from each other by one water molecule in the channel. Both of these phases have triclinic unit cells that are closely related to that of the calcined rhombohedral phase. The structure of the low-temperature (10 °C), fully rehydrated phase (phase B) was elucidated by combining high-resolution synchrotron powder diffraction with solid-state NMR techniques. Coordination of three of the six Al atoms to water molecules causes the deformation of the framework and the reduction of the symmetry. Rietveld refinement of the structure of phase B in the triclinic space group P1 (a = 9.026, b = 9.338, c = 9.508 Å, α = 95.1°, β = 104.1°, and γ = 96.6°) converged with RF = 0.079 and RWP = 0.176 (Rexp = 0.087). Framework connectivities derived from the structure were used to assign 31P NMR lines as well as part of the 27Al NMR signal.",
publisher = "American Chemical Society",
journal = "The Journal of Physical Chemistry B",
title = "NMR Characterization and Rietveld Refinement of the Structure of Rehydrated AlPO4-34",
pages = "5705-5697",
volume = "104",
doi = "10.1021/jp000455a"
}

Tuel, A., Caldarelli, S., Meden, A., McCusker, L. B., Baerlocher, C. B., Ristic, A., Rajić, N., Mali, G.,& Kaučič, V.. (2000). NMR Characterization and Rietveld Refinement of the Structure of Rehydrated AlPO4-34. in The Journal of Physical Chemistry B
American Chemical Society., 104, 5697-5705.
https://doi.org/10.1021/jp000455a

Tuel A, Caldarelli S, Meden A, McCusker LB, Baerlocher CB, Ristic A, Rajić N, Mali G, Kaučič V. NMR Characterization and Rietveld Refinement of the Structure of Rehydrated AlPO4-34. in The Journal of Physical Chemistry B. 2000;104:5697-5705.
doi:10.1021/jp000455a .

Tuel, Alain, Caldarelli, Stefano, Meden, Anton, McCusker, Lynne B., Baerlocher, Christian Baerlocher, Ristic, Alenka, Rajić, Nevenka, Mali, Gregor, Kaučič, Venčeslav, "NMR Characterization and Rietveld Refinement of the Structure of Rehydrated AlPO4-34" in The Journal of Physical Chemistry B, 104 (2000):5697-5705,
https://doi.org/10.1021/jp000455a . .

TY  - JOUR
AU  - Rajić, Nevenka
AU  - Ristić, Alenka
AU  - Tuel, Alain
AU  - Kaučič, Venčeslav
PY  - 1997
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/6390
AB  - The fluoride route of synthesis of AIPO,-34 is also successful in the preparation of its cobalt modified product (CoAPO-34). The triclinic precursor of CoAPO-34 has been synthesized in the presence of HF and piperidine. Although two different Al sites are available for cobalt(ll) substitution (i.e., tetrahedral and octahedral sites), cobalt(ll) substitutes exclusively the tetrahedral aluminum. Calcination of the as-synthesized material results in oxidation of Cofll). This is evident from the electron absorption, electron paramagnetic resonance, and infrared measurements. The 
calcined product exhibits a particular sensitivity to humidity: upon hydration, the chabazite struc ture transforms to a new one. However, the hydration is a reversible process: thermal evacuation of the hydrated sample causes a complete return to the chabazite material. In comparison with the CoAPO-34 obtained in a nonfluoride medium, the CoAPO-34 prepared in this work exhibits a higher thermal stability.
PB  - Elsevier Science Inc.
T2  - Zeolites
T1  - A CoAPO-34 derived from a triclinic  precursor prepared in the presence of HF
EP  - 118
IS  - 2-3
SP  - 115
VL  - 18
DO  - 10.1016/S0144-2449(96)00132-7
UR  - https://hdl.handle.net/21.15107/rcub_technorep_6390
ER  - 

@article{
author = "Rajić, Nevenka and Ristić, Alenka and Tuel, Alain and Kaučič, Venčeslav",
year = "1997",
abstract = "The fluoride route of synthesis of AIPO,-34 is also successful in the preparation of its cobalt modified product (CoAPO-34). The triclinic precursor of CoAPO-34 has been synthesized in the presence of HF and piperidine. Although two different Al sites are available for cobalt(ll) substitution (i.e., tetrahedral and octahedral sites), cobalt(ll) substitutes exclusively the tetrahedral aluminum. Calcination of the as-synthesized material results in oxidation of Cofll). This is evident from the electron absorption, electron paramagnetic resonance, and infrared measurements. The 
calcined product exhibits a particular sensitivity to humidity: upon hydration, the chabazite struc ture transforms to a new one. However, the hydration is a reversible process: thermal evacuation of the hydrated sample causes a complete return to the chabazite material. In comparison with the CoAPO-34 obtained in a nonfluoride medium, the CoAPO-34 prepared in this work exhibits a higher thermal stability.",
publisher = "Elsevier Science Inc.",
journal = "Zeolites",
title = "A CoAPO-34 derived from a triclinic  precursor prepared in the presence of HF",
pages = "118-115",
number = "2-3",
volume = "18",
doi = "10.1016/S0144-2449(96)00132-7",
url = "https://hdl.handle.net/21.15107/rcub_technorep_6390"
}

Rajić, N., Ristić, A., Tuel, A.,& Kaučič, V.. (1997). A CoAPO-34 derived from a triclinic  precursor prepared in the presence of HF. in Zeolites
Elsevier Science Inc.., 18(2-3), 115-118.
https://doi.org/10.1016/S0144-2449(96)00132-7
https://hdl.handle.net/21.15107/rcub_technorep_6390

Rajić N, Ristić A, Tuel A, Kaučič V. A CoAPO-34 derived from a triclinic  precursor prepared in the presence of HF. in Zeolites. 1997;18(2-3):115-118.
doi:10.1016/S0144-2449(96)00132-7
https://hdl.handle.net/21.15107/rcub_technorep_6390 .

Rajić, Nevenka, Ristić, Alenka, Tuel, Alain, Kaučič, Venčeslav, "A CoAPO-34 derived from a triclinic  precursor prepared in the presence of HF" in Zeolites, 18, no. 2-3 (1997):115-118,
https://doi.org/10.1016/S0144-2449(96)00132-7 .,
https://hdl.handle.net/21.15107/rcub_technorep_6390 .