X-ray diffraction and Raman spectroscopy for lead halide perovskites

The formation and study of a partial solid solution <a></a><a>Az1-xFAxPbBr3</a>, using ‘similar’ sized cations azetidinium (Az+) and formamidinium (FA+), was explored via mechanosynthesis and precipitation synthesis. The composition and lattice parameters of samples from both syntheses were analysed by 1H NMR and Rietveld refinement of the powder X-ray diffraction. A clear mismatch in the composition of the perovskite was found between the precipitated samples and the corresponding solutions. Such a mismatch was not observed for samples obtained via mechanosynthesis. The discrepancy suggests products are kinetically-controlled during precipitation, compared to thermodynamically-controlled mechanosynthesis. Furthermore, the cell volume as a function of composition in both 6H (Az-rich) and 3C (FA-rich) solid solutions suggests that FA+ is actually smaller than Az+, contradicting the literature. In the 3C (Az-poor) solid solutions, the extent of Az1-xFAxPbBr3 is unexpectedly smaller than Az1-xMAxPbBr3, again in contradiction to the expectation based on the reported cation sizes. These results indicate that other factors, as yet unidentified, must also contribute to the solid solution formation of organic-inorganic hybrid perovskites, not simply the relative sizes of the A-site cations.

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Progressive Polytypism and Bandgap Tuning in Azetidinium Lead Halide Perovskites

10.26434/chemrxiv.14502372.v1 ◽

2021 ◽

Author(s):

Jiyu Tian ◽

David Cordes ◽

Alexandra Slawin ◽

Eli Zysman-Colman ◽

Finlay Morrison

Keyword(s):

Linear Variation ◽

Ambient Conditions ◽

X Ray Diffraction ◽

X Ray ◽

Vegard’S Law ◽

The Family ◽

Halide Perovskites ◽

Diffraction Patterns ◽

Bandgap Tuning ◽

Lead Halide

<div><div><div>Mixed halide azetidinium lead perovskites AzPbBr3-xXx (X = Cl or I) were obtained by mechanosynthesis. With varying halide composition from Cl- to Br- to I-; the chloride and bromide analogs both form in the hexagonal 6H polytype while the iodide adopts the 9R polytype. An intermediate 4H polytype is observed for mixed Br/I compositions. Overall the structure progresses from 6H to 4H to 9R perovskite polytype with varying halide composition. Rietveld refinement of the powder X-ray diffraction patterns revealed a linear variation in unit cell volume as a function of the average radius of the anion, which is not only observed within the solid solution of each polytype (according to Vegard’s law) but extends uniformly across all three polytypes. This is correlated with a progressive (linear) tuning of the bandgap from 3.41 to 2.00 eV. Regardless of halide, the family of azetidinium halide perovskite polytypes are highly stable, with no discernible change in properties over more than 6 months under ambient conditions</div></div></div>

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Progressive Polytypism and Bandgap Tuning in Azetidinium Lead Halide Perovskites

10.26434/chemrxiv.14502372 ◽

2021 ◽

Author(s):

Jiyu Tian ◽

David Cordes ◽

Alexandra Slawin ◽

Eli Zysman-Colman ◽

Finlay Morrison

Keyword(s):

Linear Variation ◽

Ambient Conditions ◽

X Ray Diffraction ◽

X Ray ◽

Vegard’S Law ◽

The Family ◽

Halide Perovskites ◽

Diffraction Patterns ◽

Bandgap Tuning ◽

Lead Halide

<div><div><div>Mixed halide azetidinium lead perovskites AzPbBr3-xXx (X = Cl or I) were obtained by mechanosynthesis. With varying halide composition from Cl- to Br- to I-; the chloride and bromide analogs both form in the hexagonal 6H polytype while the iodide adopts the 9R polytype. An intermediate 4H polytype is observed for mixed Br/I compositions. Overall the structure progresses from 6H to 4H to 9R perovskite polytype with varying halide composition. Rietveld refinement of the powder X-ray diffraction patterns revealed a linear variation in unit cell volume as a function of the average radius of the anion, which is not only observed within the solid solution of each polytype (according to Vegard’s law) but extends uniformly across all three polytypes. This is correlated with a progressive (linear) tuning of the bandgap from 3.41 to 2.00 eV. Regardless of halide, the family of azetidinium halide perovskite polytypes are highly stable, with no discernible change in properties over more than 6 months under ambient conditions</div></div></div>

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Size Isn’t Everything - Compositional Variation in Hybrid Organic-Inorganic Lead Halide Perovskites: Kinetically- versus Thermodynamically-controlled Synthesis

10.26434/chemrxiv.13729063.v1 ◽

2021 ◽

Author(s):

Jiyu Tian ◽

Eli Zysman-Colman ◽

Finlay Morrison

Keyword(s):

Solid Solution ◽

Solid Solutions ◽

Compositional Variation ◽

X Ray Diffraction ◽

Solid Solution Formation ◽

X Ray ◽

H Nmr ◽

Halide Perovskites ◽

A Site ◽

Lead Halide

The formation and study of a partial solid solution <a></a><a>Az1-xFAxPbBr3</a>, using ‘similar’ sized cations azetidinium (Az+) and formamidinium (FA+), was explored via mechanosynthesis and precipitation synthesis. The composition and lattice parameters of samples from both syntheses were analysed by 1H NMR and Rietveld refinement of the powder X-ray diffraction. A clear mismatch in the composition of the perovskite was found between the precipitated samples and the corresponding solutions. Such a mismatch was not observed for samples obtained via mechanosynthesis. The discrepancy suggests products are kinetically-controlled during precipitation, compared to thermodynamically-controlled mechanosynthesis. Furthermore, the cell volume as a function of composition in both 6H (Az-rich) and 3C (FA-rich) solid solutions suggests that FA+ is actually smaller than Az+, contradicting the literature. In the 3C (Az-poor) solid solutions, the extent of Az1-xFAxPbBr3 is unexpectedly smaller than Az1-xMAxPbBr3, again in contradiction to the expectation based on the reported cation sizes. These results indicate that other factors, as yet unidentified, must also contribute to the solid solution formation of organic-inorganic hybrid perovskites, not simply the relative sizes of the A-site cations.

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Raman spectroscopy and X-ray diffraction of lithium niobate at temperatures up to 1300○-4.80pt○C

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:2005126021 ◽

2005 ◽

Vol 126 ◽

pp. 101-105 ◽

Cited By ~ 1

Author(s):

B. Moulin ◽

L. Hennet ◽

D. Thiaudière ◽

P. Melin ◽

P. Simon

Keyword(s):

Raman Spectroscopy ◽

Lithium Niobate ◽

X Ray Diffraction ◽

X Ray

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Structural and Raman Vibrational Studies ofCeO2-Bi2O3Oxide System

Advances in Materials Science and Engineering ◽

10.1155/2009/502437 ◽

2009 ◽

Vol 2009 ◽

pp. 1-4 ◽

Cited By ~ 8

Author(s):

L. Bourja ◽

B. Bakiz ◽

A. Benlhachemi ◽

M. Ezahri ◽

J. C. Valmalette ◽

...

Keyword(s):

Solid Solution ◽

Raman Spectroscopy ◽

Phase Changes ◽

Phase System ◽

X Ray Diffraction ◽

X Ray ◽

Vibrational Studies ◽

Coprecipitation Route

A series of ceramics samples belonging to theCeO2-Bi2O3phase system have been prepared via a coprecipitation route. The crystallized phases were obtained by heating the solid precursors at600∘Cfor 6 hours, then quenching the samples. X-ray diffraction analyses show that forx<0.20a solid solutionCe1−xBixO2−x/2with fluorine structure is formed. For x ranging between 0.25 and 0.7, a tetragonalβ′phase coexisting with the FCC solid solution is observed. For x ranging between 0.8 and 0.9, a new tetragonalβphase appears. Theβ′phase is postulated to be a superstructure of theβphase. Finally, close tox=1, the classical monoclinicα Bi2O3structure is observed. Raman spectroscopy confirms the existence of the phase changes as x varies between 0 and 1.

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