Subcategory: Materials Science
Katrina Verlinde - The Pennsylvania State University
Co-Author(s): Dr. Ronald Redwing, The Pennsylvania State University, University Park, PA; Dr. Seng Huat Lee, The Pennsylvania State University, University Park, PA
Ruddlesden-Popper (RP) layered perovskite crystals of the family Srn+1ZrnS3n+1 (n=0, 1, 2, …∞) are theoretically predicted to have ferroelectric properties making them ideal for applications in photovoltaics, sensing, and visible lighting. In this study, both experimental and theoretical x-ray diffraction (XRD) patterns were used to verify the synthesis of a previously unreported n=1 phase of the Srn+1ZrnS3n+1 family, Sr2ZrS4. SrS, Zr, and S powders were compounded via a solid-state reaction with I2 carrier gas. The ampoules containing the source materials were gradually heated to 950°C over 15 hours, held constant for 15 hours, then raised to 1050°C over 12 hours. Once the reaction was complete, the compound’s x-ray powder diffraction (XRD) pattern was observed to have several unexpected peaks, in addition to the peaks known to be associated with our source materials and SrZrS3 (n=∞), an expected product. The objective of this project was to use the unknown peaks to ascertain if the product was a synthesis of an as-of-yet unreported phase of the RP family Srn+1ZrnS3n+1, hypothesized to be either the Sr2ZrS4 (n=1) or Sr3Zr2S7 (n=2) phase. Theoretical diffraction patterns for these phases were calculated with CrystalMaker 10.3 and CrystalDiffract 6.7 software by utilizing space group properties and unit cell lattice parameters of n=1 and n=2 phases of the related RP families: Ban+1ZrnS3n+1, Srn+1ZrnO3n+1, and Ban+1ZrnO3n+1. Using the known properties of these crystals, the relationships between lattice parameters when phase and elemental site makeup were changed were obtained and used to predict XRD patterns for Sr2ZrS4 and Sr3Zr2S7. This data was compared to the original sample compound data, aligning the pattern so that the first two unidentified peaks matched the theoretical pattern. Having done this, the remaining unidentified peaks match very closely with the Sr2ZrS4 (n=1) phase, with Sr3Zr2S7 (n=2) producing a much lower fidelity match. Thus, the synthesized crystal samples were found to contain a mixture of crystals composed of source materials, SrZrS3 (n=∞), and Sr2ZrS4, the first known experimental product of the n=1 phase of Srn+1ZrnS3n+1 RP crystals.
Funder Acknowledgement(s): We would like to thank the National Science Foundation EFRI REM (EFMA-1433378) for funding this research project.
Faculty Advisor: Dr. Ronald Redwing, email@example.com
Role: I performed all x-ray powder diffractions and was responsible for analyzing all of the data that was produced. I also learned to use the CrystalMaker software and took what I learned to normalize and compare the data as described above.