Our members have published numerous papers, with many delving into the various ferroelectric materials for both electric and energy applications. Check out some of Dr. Garten’s papers below for more information on photometric, bulk photovoltaic effect, multiferroics, magnetoelectric, piezoelectric and dielectric materials and applications.
Understanding Crystallization Pathways Leading to Manganese Oxide Polymorph Formation
Hydrothermal synthesis can be quite challenging in metal oxide systems with diverse polymorphism, as reaction products are often sensitive to subtle variations in synthesis parameters. Since this sensitivity is rooted in the non-equilibrium nature of low-temperature crystallization, we propose an ab initio framework to predict how particle size and solution composition influence polymorph stability during nucleation and growth. Click here to read more.
Negative-Pressure Polymorphs Made By Heterostructural Alloying
Polymorphism, the ability of a material to adopt multiple structures, is a fascinating natural phenomenon. Many polymorphs with unusual properties are routinely synthesized by compression under positive pressure. However, changing a material’s structure by applying tension under negative pressure is much more difficult. Within this paper, we show how negative-pressure polymorphs can be synthesized by mixing materials with different crystal structures—a general approach that should be applicable to many materials. Learn more.
Theory-Guided Synthesis of a Metastable Lead-Free Piezoelectric Polymorph
Many technologically critical materials are metastable under ambient conditions, yet the understanding of how to rationally design and guide the synthesis of these materials is limited. This work presents an integrated approach that targets a metastable lead‐free piezoelectric polymorph of SrHfO3. Learn more.
The Existence and Impact of Persistent Ferroelectric Domains in MAPbI3
Methylammonium lead iodide (MAPbI3) exhibits exceptional photovoltaic performance, but substantial controversy remains over the existence and impact of ferroelectricity on the photovoltaic response. With ferroelectric domain engineering, we confirmed ferroelectricity in MAPbI3 single crystals and demonstrated mediation of the electronic response. Click here to keep reading.
Selective Brookite Polymorph Formation Related to the Amorphous Precursor State in TiO2 Thin Films
A wide variety of brookite TiO2 synthesis methods have been published over the past several decades, but few studies discuss the underlying mechanism that stabilizes brookite over its stable counterparts, rutile and anatase. Here, we investigate of the effect of pulsed laser deposition parameters on the as-deposited amorphous precursor titania thin films, which subsequently crystallize into stable and metastable TiO2 polymorphs upon annealing. Read our findings here.
Utilizing TiO2 Amorphous Precursors for Polymorph Selection: An in situ TEM study of phase formation and kinetics
Selective synthesis of metastable polymorphs requires a fundamental understanding of the complex energy landscapes in which these phases form. Recently, the development of in situ high temperature and controlled atmosphere transmission electron microscopy has enabled the direct observation of nucleation, growth, and phase transformations with near atomic resolution. In this work, we directly observe the crystallization behavior of amorphous TiO2 thin films grown under different pulsed laser deposition conditions and quantify the mechanisms behind metastable crystalline polymorph stabilization. Learn more.
Stromataxic Stabilization of a Metastable Layered ScFeO3 Polymorph
Metastable polymorphs—materials with the same stoichiometry as the ground state but a different crystal structure— enable many critical technologies. This work describes the development of a stabilization approach for metastable polymorphs that are difficult to achieve through other stabilization techniques (such as epitaxy or quenching) called stromataxy. Stromataxy is a method based on controlling the precursor structure during the initial stages of material growth to dictate phase formation. Click here to find out how we chose to illustrate this approach.
Phase Formation of Manganese Oxide Thin Films Using Pulsed Laser Deposition
Manganese oxides have enabled a wide range of technologies including oxygen evolution catalysts, lithium ion batteries, and thermochemical water splitting. However, the variable oxidation state and rich polymorphism of manganese oxides make it difficult to find the processing conditions to target a particular phase of manganese oxide. As targeted synthesis requires a more complete understanding of the phase space and the impact of multiple processing variables on phase formation, we demonstrated the impact of substrate temperature, total deposition pressure, partial pressure of oxygen, and target composition on the phase formation of manganese oxides grown using combinatorial pulsed laser deposition (PLD). Click here to continue reading.
For further reading, more papers from Dr. Garten can be found here.