The Role of Compositional and Structural Dimensionality in Dion-Jacobson Layered Perovskites: A Study of Double to Quadruple Layers by Synthetic and Computational Methods

Author

• Roshni Bhuvan, University of New Orleans, New OrleansFollow

ORCID ID

0000-0001-9274-0900

Date of Award

5-2026

Degree Type

Dissertation

Degree Name

Ph.D.

Degree Program

Chemistry

Department

Chemistry

Major Professor

Dr John B Wiley

Second Advisor

Dr Steven W Rick

Abstract

Understanding the variables governing specific structural features is vital to the synthesis of materials with desirable properties. Scientists can continue tune materials in beneficial ways by determining the underlying logic behind certain structure-property relationships. Exploring these spaces synergistically with experimental and computational approaches is advantageous, illuminating novel reaction pathways, while still being grounded in what is approachable synthetically. Layered perovskites have been of much interest in the recent years due to their magnetic and electrical properties, but also because of their amenability in serving as a topotactic host. The research presented here summarizes the efforts of deconvoluting the effect of interlayer composition and perovskite slab thickness on the final structure of various Dion-Jacobson layered materials. Direct ceramic methods and topochemical ion-exchange reactions were used to create a series of double-, triple- and quadruple-layered alkali niobates to probe these factors further. In the double-layered series, A_1-xA′_xLaNb₂O₇ (A/A′= Li, Na, K, Rb, Cs) solid solutions were synthesized to determine the influence of interlayer cation size on the orientation of perovskite slabs in the compound. Results and characterization of these materials can be found in Chapter 2, and the expansion into the analogous A_1-xA′_xCa₂Nb₃O₁₀ (A/A′= Li, Na, K, Rb, Cs) triple-layered compounds in Chapter 4. In Chapter 5, topotactic synthesis and characterization of ACa₂NaNb₄O₁₃ (A = Li, K) were also done to obtain data on the influence of perovskite slab thickness on final structure-property relationships. In the study of double-layered ALaNb₂O₇ (A = Li, Na, K, Rb, Cs), thermal anomalies in NaLaNb₂O₇ were investigated via high-temperature X-ray diffraction (XRD) and differential scanning calorimetry (DSC), resulting in the discovery of high-temperature polymorphism in this species (Chapter 3). This led to the application of density functional theory (DFT) to explore the energetics behind the successful ion‑exchange reactions used for the synthesis of ALaNb₂O₇ (A = Li, Na, K) members. Chapter 6 shows the results of these calculations, which has good correlation to what is seen in the lab and verified reversibility in these ion-exchange reactions that has been previously unreported. The trends over the entirety of this dissertation seem to indicate the high influence of interlayer cation size and nature on the perovskite slab orientation around the interlayer gallery, while the thickness of the perovskite slab has the highest impact on the thermal stability of the material.

Rights

The University of New Orleans and its agents retain the non-exclusive license to archive and make accessible this dissertation or thesis in whole or in part in all forms of media, now or hereafter known. The author retains all other ownership rights to the copyright of the thesis or dissertation.

Recommended Citation

Bhuvan, Roshni, "The Role of Compositional and Structural Dimensionality in Dion-Jacobson Layered Perovskites: A Study of Double to Quadruple Layers by Synthetic and Computational Methods" (2026). University of New Orleans Theses and Dissertations. 3395.
https://scholarworks.uno.edu/td/3395