Cova de Can Sadurní, la transformació d’un jaciment. L’episodi sepulcral del neolític postcardial

The present study deals with the structural characterization and classification of the novel compounds <b>1</b>–<b>8</b> into perovskite subclasses and proceeds in extracting the structure–band gap relationships between them. The compounds were obtained from the employment of small, 3–5-atom-wide organic ammonium ions seeking to discover new perovskite-like compounds. The compounds reported here adopt unique or rare structure types akin to the prototype structure perovskite. When trimethylammonium (TMA) was employed, we obtained TMASnI₃ (<b>1</b>), which is our reference compound for a “perovskitoid” structure of face-sharing octahedra. The compounds EASnI₃ (<b>2b</b>), GASnI₃ (<b>3a</b>), ACASnI₃ (<b>4</b>), and IMSnI₃ (<b>5</b>) obtained from the use of ethylammonium (EA), guanidinium (GA), acetamidinium (ACA), and imidazolium (IM) cations, respectively, represent the first entries of the so-called “hexagonal perovskite polytypes” in the hybrid halide perovskite library. The hexagonal perovskites define a new family of hybrid halide perovskites with a crystal structure that emerges from a blend of corner- and face-sharing octahedral connections in various proportions. The small organic cations can also stabilize a second structural type characterized by a crystal lattice with reduced dimensionality. These compounds include the two-dimensional (2D) perovskites GA₂SnI₄ (<b>3b</b>) and IPA₃Sn₂I₇ (<b>6b</b>) and the one-dimensional (1D) perovskite IPA₃SnI₅ (<b>6a</b>). The known 2D perovskite BA₂MASn₂I₇ (<b>7</b>) and the related all-inorganic 1D perovskite “RbSnF₂I” (<b>8</b>) have also been synthesized. All compounds have been identified as medium-to-wide-band-gap semiconductors in the range of <i>E</i>_g = 1.90–2.40 eV, with the band gap progressively decreasing with increased corner-sharing functionality and increased torsion angle in the octahedral connectivity

Divergence in the Behavior of the Charge Density Wave in <i>RE</i>Te₃ (<i>RE </i>= Rare-Earth Element) with Temperature and <i>RE</i> Element

Comparable changes in the volume of RETe3 materials caused by temperature and RE size have opposite trends to the incommensurate charge density wave modulation. This is unique behavior among all reported charge density wave materials

A Double Charge Density Wave in the Single Tellurium Square Net in Cu_0.63EuTe₂?

A Double Charge Density Wave in the Single Tellurium Square Net in Cu0.63EuTe2

Inorganic Single Wall Nanotubes of SbPS₄_-<i>_x</i>Se<i>_x</i> (0 ≤ <i>x</i> ≤ 3) with Tunable Band Gap

A new ternary member, SbPS4, has been added to the growing inorganic nanotube family. This material naturally forms bundles of long, single wall nanotubes

Inorganic Single Wall Nanotubes of SbPS₄_-<i>_x</i>Se<i>_x</i> (0 ≤ <i>x</i> ≤ 3) with Tunable Band Gap

A new ternary member, SbPS4, has been added to the growing inorganic nanotube family. This material naturally forms bundles of long, single wall nanotubes

Charge Density Waves in the Square Nets of Tellurium of <i>AMRE</i>Te₄ (<i>A </i>= K, Na; <i>M</i> = Cu, Ag; <i>RE</i> = La, Ce)

The charge density wave distortions of the square nets of tellurium in AMRETe4 (A = K, Na; M = Cu, Ag; RE = La, Ce) and RETe3 are influenced by the degree of separation and interaction of the tellurium nets. Each combination of A-M-RE in this family generates a unique CDW pattern

A Double Charge Density Wave in the Single Tellurium Square Net in Cu_0.63EuTe₂?

A Double Charge Density Wave in the Single Tellurium Square Net in Cu0.63EuTe2

Divergence in the Behavior of the Charge Density Wave in <i>RE</i>Te₃ (<i>RE </i>= Rare-Earth Element) with Temperature and <i>RE</i> Element

Comparable changes in the volume of RETe3 materials caused by temperature and RE size have opposite trends to the incommensurate charge density wave modulation. This is unique behavior among all reported charge density wave materials

Charge Density Waves in the Square Nets of Tellurium of <i>AMRE</i>Te₄ (<i>A </i>= K, Na; <i>M</i> = Cu, Ag; <i>RE</i> = La, Ce)

The charge density wave distortions of the square nets of tellurium in AMRETe4 (A = K, Na; M = Cu, Ag; RE = La, Ce) and RETe3 are influenced by the degree of separation and interaction of the tellurium nets. Each combination of A-M-RE in this family generates a unique CDW pattern

Divergence in the Behavior of the Charge Density Wave in <i>RE</i>Te₃ (<i>RE </i>= Rare-Earth Element) with Temperature and <i>RE</i> Element

Comparable changes in the volume of RETe3 materials caused by temperature and RE size have opposite trends to the incommensurate charge density wave modulation. This is unique behavior among all reported charge density wave materials