This research investigates the high-pressure behavior of the Ca(Ti0.95Ge0.05)O3 perovskite, a candidate of the locked-tilt perovskite family (orthorhombic compounds characterized by the absence of changes in the octahedral tilt and volume reduction under pressure controlled solely by isotropic compression). The study combines experimental high-pressure synchrotron diffraction data with density functional theory (DFT) calculations, complemented by the X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), to understand the structural evolution of the perovskite under pressure. The results show that CTG undergoes nearly isotropic compression with the same compressibility along all three unit-cell axes (i.e., Ka0 = Kb0 = Kc0, giving a normalized cell distortion factor with pressure dnorm(P) = 1). However, a modest increase in octahedral tilting with pressure is revealed by DFT calculations, qualifying CTG as a new type of GdFeO3-type perovskite that exhibits both isotropic compression and nonlocked tilting. This finding complements two existing types: perovskites with anisotropic compression and tilting changes and those with isotropic compression and locked tilting. The multimethod approach provides valuable insights into the structural evolution of locked-tilt perovskites under high pressure and establishes a protocol for the efficient study of complex high-pressure systems. The results have implications for the design of new functional materials with desirable properties.

Structure Evolution of Ge-Doped CaTiO3 (CTG) at High Pressure: Search for the First 2:4 Locked-Tilt Perovskite by Synchrotron X‑ray Diffraction and DFT Calculations

Matteo Ardit
Primo
;
Sonia Conte
Secondo
;
Giuseppe Cruciani
Penultimo
;
2023

Abstract

This research investigates the high-pressure behavior of the Ca(Ti0.95Ge0.05)O3 perovskite, a candidate of the locked-tilt perovskite family (orthorhombic compounds characterized by the absence of changes in the octahedral tilt and volume reduction under pressure controlled solely by isotropic compression). The study combines experimental high-pressure synchrotron diffraction data with density functional theory (DFT) calculations, complemented by the X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), to understand the structural evolution of the perovskite under pressure. The results show that CTG undergoes nearly isotropic compression with the same compressibility along all three unit-cell axes (i.e., Ka0 = Kb0 = Kc0, giving a normalized cell distortion factor with pressure dnorm(P) = 1). However, a modest increase in octahedral tilting with pressure is revealed by DFT calculations, qualifying CTG as a new type of GdFeO3-type perovskite that exhibits both isotropic compression and nonlocked tilting. This finding complements two existing types: perovskites with anisotropic compression and tilting changes and those with isotropic compression and locked tilting. The multimethod approach provides valuable insights into the structural evolution of locked-tilt perovskites under high pressure and establishes a protocol for the efficient study of complex high-pressure systems. The results have implications for the design of new functional materials with desirable properties.
2023
Ardit, Matteo; Conte, Sonia; Belmonte, Donato; Menescardi, Francesca; Pollastri, Simone; Cruciani, Giuseppe; Dondi, Michele
File in questo prodotto:
File Dimensione Formato  
ArditIC62 - 2023 - Structure evolution of CTG at high pressure.pdf

accesso aperto

Descrizione: Full text editoriale
Tipologia: Full text (versione editoriale)
Licenza: Creative commons
Dimensione 6.94 MB
Formato Adobe PDF
6.94 MB Adobe PDF Visualizza/Apri
ic3c02645_si_001.pdf

accesso aperto

Descrizione: Supporting Information
Tipologia: Altro materiale allegato
Licenza: Creative commons
Dimensione 414.2 kB
Formato Adobe PDF
414.2 kB Adobe PDF Visualizza/Apri

I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2525690
Citazioni
  • ???jsp.display-item.citation.pmc??? 0
  • Scopus 0
  • ???jsp.display-item.citation.isi??? 0
social impact