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Book ; Online: Bulk synthesis of Zn$_3$WN$_4$ via solid-state metathesis

Rom, Christopher L. / O'Donnell, Shaun / Huang, Kayla / Klein, Ryan A. / Kramer, Morgan J. / Smaha, Rebecca W. / Zakutayev, Andriy

2024

Abstract: Ternary nitrides are of growing technological importance, with applications as semiconductors, catalysts, and magnetic materials; however, new synthetic tools are needed to advance materials discovery efforts. Here, we show that Zn$_3$WN$_4$ can be ... ...

Abstract	Ternary nitrides are of growing technological importance, with applications as semiconductors, catalysts, and magnetic materials; however, new synthetic tools are needed to advance materials discovery efforts. Here, we show that Zn$_3$WN$_4$ can be synthesized via metathesis reactions between Li$_6$WN$_4$ and Zn$X_2$ ($X$ = Br, Cl, F). In situ synchrotron powder X-ray diffraction and differential scanning calorimetry show that the reaction onset is correlated with the Zn$X_2$ melting point and that product purity is inversely correlated with the reaction's exothermicity. High resolution synchrotron powder X-ray diffraction measurements show that this bulk synthesis produces a structure with substantial cation ordering, as opposed to the disordered structure initially discovered via thin film sputtering. Diffuse reflectance spectroscopy reveals that Zn$_3$WN$_4$ powders exhibit two optical absorption onsets at 2.5 eV and 4.0 eV, indicating wide-bandgap semiconducting behavior and suggesting a small amount of structural disorder. We hypothesize that this synthesis strategy is generalizable because many potential Li-$M$-N precursors (where $M$ is a metal) are available for synthesizing new ternary nitride materials. This work introduces a promising synthesis strategy that will accelerate the discovery of novel functional ternary nitrides and other currently inaccessible materials.
Keywords	Condensed Matter - Materials Science
Subject code	540
Publishing date	2024-01-03
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Mechanistically Guided Materials Chemistry: Synthesis of Ternary Nitrides, CaZrN

Rom, Christopher L / Novick, Andrew / McDermott, Matthew J / Yakovenko, Andrey A / Gallawa, Jessica R / Tran, Gia Thinh / Asebiah, Dominic C / Storck, Emily N / McBride, Brennan C / Miller, Rebecca C / Prieto, Amy L / Persson, Kristin A / Toberer, Eric / Stevanović, Vladan / Zakutayev, Andriy / Neilson, James R

Journal of the American Chemical Society

2024 Volume 146, Issue 6, Page(s) 4001–4012

Abstract: Recent computational studies have predicted many new ternary nitrides, revealing synthetic opportunities in this underexplored phase space. However, synthesizing new ternary nitrides is difficult, in part because intermediate and product phases often ... ...

Abstract	Recent computational studies have predicted many new ternary nitrides, revealing synthetic opportunities in this underexplored phase space. However, synthesizing new ternary nitrides is difficult, in part because intermediate and product phases often have high cohesive energies that inhibit diffusion. Here, we report the synthesis of two new phases, calcium zirconium nitride (CaZrN
Language	English
Publishing date	2024-01-30
Publishing country	United States
Document type	Journal Article
ZDB-ID	3155-0
ISSN	1520-5126 ; 0002-7863
ISSN (online)	1520-5126
ISSN	0002-7863
DOI	10.1021/jacs.3c12114
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Book ; Online: Bulk and film synthesis pathways to ternary magnesium tungsten nitrides

Rom, Christopher L. / Smaha, Rebecca W. / Knebel, Callan A. / Heinselman, Karen N. / Neilson, James R. / Bauers, Sage R. / Zakutayev, Andriy

2023

Abstract: Bulk solid state synthesis of nitride materials usually leads to thermodynamically stable, cation-ordered crystal structures, whereas thin film synthesis tends to favor disordered, metastable phases. This dichotomy is inconvenient both for basic ... ...

Abstract	Bulk solid state synthesis of nitride materials usually leads to thermodynamically stable, cation-ordered crystal structures, whereas thin film synthesis tends to favor disordered, metastable phases. This dichotomy is inconvenient both for basic materials discovery, where non-equilibrium thin film synthesis methods can be useful to overcome reaction kinetic barriers, and for practical technology applications where stable ground state structures are sometimes required. Here, we explore the uncharted Mg-W-N chemical phase space, using rapid thermal annealing to reconcile the differences between thin film and bulk powder syntheses. Combinatorial co-sputtering synthesis from Mg and W targets in a N$_2$ environment yielded cation-disordered Mg-W-N phases in the rocksalt (0.1< Mg/(Mg+W) <0.9), and hexagonal boron nitride (0.7< Mg/(Mg+W) <0.9) structure types. In contrast, bulk synthesis produced a cation-ordered polymorph of MgWN$_2$ that consists of alternating layers of rocksalt-like [MgN$_6$] octahedra and nickeline-like [WN$_6$] trigonal prisms (denoted "rocksaline"). Thermodynamic calculations corroborate these observations, showing rocksaline MgWN$_2$ is stable while other polymorphs are metastable. We also show that rapid thermal annealing can convert disordered rocksalt films to this cation-ordered polymorph near the MgWN$_2$ stoichiometry. Electronic structure calculations suggest that this rocksalt-to-rocksaline structural transformation should also drive a metallic-to-semiconductor transformation. In addition to revealing three new phases (rocksalt MgWN$_2$ and Mg$_3$WN$_4$, hexagonal boron nitride Mg$_3$WN$_4$, and rocksaline MgWN$_2$), these findings highlight how rapid thermal annealing can control polymorphic transformations, adding a new strategy for exploration of thermodynamic stability in uncharted phase spaces.
Keywords	Condensed Matter - Materials Science
Subject code	540
Publishing date	2023-06-03
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Selectivity in Yttrium Manganese Oxide Synthesis via Local Chemical Potentials in Hyperdimensional Phase Space.

Todd, Paul K / McDermott, Matthew J / Rom, Christopher L / Corrao, Adam A / Denney, Jonathan J / Dwaraknath, Shyam S / Khalifah, Peter G / Persson, Kristin A / Neilson, James R

Journal of the American Chemical Society

2021

Abstract: In sharp contrast to molecular synthesis, materials synthesis is generally presumed to lack selectivity. The few known methods of designing selectivity in solid-state reactions have limited scope, such as topotactic reactions or strain stabilization. ... ...

Abstract	In sharp contrast to molecular synthesis, materials synthesis is generally presumed to lack selectivity. The few known methods of designing selectivity in solid-state reactions have limited scope, such as topotactic reactions or strain stabilization. This contribution describes a general approach for searching large chemical spaces to identify selective reactions. This novel approach explains the ability of a nominally "innocent" Na
Language	English
Publishing date	2021-09-07
Publishing country	United States
Document type	Journal Article
ZDB-ID	3155-0
ISSN	1520-5126 ; 0002-7863
ISSN (online)	1520-5126
ISSN	0002-7863
DOI	10.1021/jacs.1c06229
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Selectivity in Yttrium Manganese Oxide Synthesis via Local Chemical Potentials in Hyperdimensional Phase Space

Todd, Paul K. / McDermott, Matthew J. / Rom, Christopher L. / Corrao, Adam A. / Denney, Jonathan J. / Dwaraknath, Shyam S. / Khalifah, Peter G. / Persson, Kristin A. / Neilson, James R.

Journal of the American Chemical Society. 2021 Sept. 07, v. 143, no. 37

2021

Abstract	In sharp contrast to molecular synthesis, materials synthesis is generally presumed to lack selectivity. The few known methods of designing selectivity in solid-state reactions have limited scope, such as topotactic reactions or strain stabilization. This contribution describes a general approach for searching large chemical spaces to identify selective reactions. This novel approach explains the ability of a nominally “innocent” Na₂CO₃ precursor to enable the metathesis synthesis of single-phase Y₂Mn₂O₇: an outcome that was previously only accomplished at extreme pressures and which cannot be achieved with closely related precursors of Li₂CO₃ and K₂CO₃ under identical conditions. By calculating the required change in chemical potential across all possible reactant-product interfaces in an expanded chemical space including Y, Mn, O, alkali metals, and halogens, using thermodynamic parameters obtained from density functional theory calculations, we identify reactions that minimize the thermodynamic competition from intermediates. In this manner, only the Na-based intermediates minimize the distance in the hyperdimensional chemical potential space to Y₂Mn₂O₇, thus providing selective access to a phase which was previously thought to be metastable. Experimental evidence validating this mechanism for pathway-dependent selectivity is provided by intermediates identified from in situ synchrotron-based crystallographic analysis. This approach of calculating chemical potential distances in hyperdimensional compositional spaces provides a general method for designing selective solid-state syntheses that will be useful for gaining access to metastable phases and for identifying reaction pathways that can reduce the synthesis temperature, and cost, of technological materials.
Keywords	density functional theory ; manganese monoxide ; temperature ; thermodynamics ; yttrium
Language	English
Dates of publication	2021-0907
Size	p. 15185-15194.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	3155-0
ISSN	1520-5126 ; 0002-7863
ISSN (online)	1520-5126
ISSN	0002-7863
DOI	10.1021/jacs.1c06229
Database	NAL-Catalogue (AGRICOLA)

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Book ; Online: Mechanistically-guided materials chemistry

Rom, Christopher L. / Novick, Andrew / McDermott, Matthew J. / Yakovenko, Andrey A. / Gallawa, Jessica R. / Tran, Gia Thinh / Asebiah, Dominic C. / Storck, Emily N. / McBride, Brennan C. / Miller, Rebecca C. / Prieto, Amy L. / Persson, Kristin A. / Toberer, Eric / Stevanović, Vladan / Zakutayev, Andriy / Neilson, James R.

synthesis of new ternary nitrides, CaZrN$_2$ and CaHfN$_2$

2023

Abstract	Recent computational studies have predicted many new ternary nitrides, revealing synthetic opportunities in this underexplored phase space. However, synthesizing new ternary nitrides is difficult, in part because intermediate and product phases often have high cohesive energies that inhibit diffusion. Here, we report the synthesis of two new phases, calcium zirconium nitride (CaZrN$_2$) and calcium hafnium nitride (CaHfN$_2$), by solid state metathesis reactions between Ca$_3$N$_2$ and $M$Cl$_4$ ($M$ = Zr, Hf). Although the reaction nominally proceeds to the target phases in a 1:1 ratio of the precursors via Ca$_3$N$_2$ + $M$Cl$_4$ $\rightarrow$ Ca$M$N$_2$ + 2 CaCl$_2$, reactions prepared this way result in Ca-poor materials (Ca$_xM_{2-x}$N$_2$, $x<1$). A small excess of Ca$_3$N$_2$ (ca. 20 mol\%) is needed to yield stoichiometric Ca$M$N$_2$, as confirmed by high-resolution synchrotron powder X-ray diffraction. In situ synchrotron X-ray diffraction studies reveal that nominally stoichiometric reactions produce Zr$^{3+}$ intermediates early in the reaction pathway, and the excess Ca$_3$N$_2$ is needed to reoxidize Zr$^{3+}$ intermediates back to the Zr$^{4+}$ oxidation state of CaZrN$_2$. Analysis of computationally-derived chemical potential diagrams rationalizes this synthetic approach and its contrast from the synthesis of MgZrN$_2$. These findings additionally highlight the utility of in situ diffraction studies and computational thermochemistry to provide mechanistic guidance for synthesis.
Keywords	Condensed Matter - Materials Science
Subject code	540
Publishing date	2023-10-30
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Selectivity in yttrium manganese oxide synthesis via local chemical potentials in hyperdimensional phase space

Todd, Paul K. / McDermott, Matthew J. / Rom, Christopher L. / Corrao, Adam A. / Denney, Jonathan J. / Dwaraknath, Shyam S. / Khalifah, Peter G. / Persson, Kristin A. / Neilson, James R.

2021

Abstract	In sharp contrast to molecular synthesis, materials synthesis is generally presumed to lack selectivity. The few known methods of designing selectivity in solid-state reactions have limited scope, such as topotactic reactions or strain stabilization. This contribution describes a general approach for searching large chemical spaces to identify selective reactions. This novel approach explains the ability of a nominally "innocent" Na$_2$CO$_3$ precursor to enable the metathesis synthesis of single-phase Y$_2$Mn$_2$O$_7$ -- an outcome that was previously only accomplished at extreme pressures and which cannot be achieved with closely related precursors of Li$_2$CO$_3$ and K$_2$CO$_3$. By calculating the required change in chemical potential across all possible reactant-product interfaces in an expanded chemical space including Y, Mn, O, alkali metals, and halogens, using thermodynamic parameters obtained from density functional theory calculations, we identify reactions that minimize the thermodynamic competition from intermediates. In this manner, only the Na-based intermediates minimize the distance in the hyperdimensional chemical potential space to Y$_2$Mn$_2$O$_7$, thus providing selective access to a phase which was previously thought to be metastable. Experimental evidence validating this mechanism for pathway-dependent selectivity is provided by intermediates identified from in situ synchrotron-based crystallographic analysis. This approach of calculating chemical potential distances in hyperdimensional compositional spaces provides a general method for designing selective solid-state syntheses that will be useful for gaining access to metastable phases and for identifying reaction pathways that can reduce the synthesis temperature, and cost, of technological materials. Comment: 30 pages with 5 figures. The first two authors contributed equally to this work
Keywords	Condensed Matter - Materials Science
Subject code	540
Publishing date	2021-04-13
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Combinatorial synthesis of cation-disordered manganese tin nitride MnSnN$_2$ thin films with magnetic and semiconducting properties

Rom, Christopher L. / Smaha, Rebecca W. / Melamed, Celeste L. / Schnepf, Rekha R. / Heinselman, Karen N. / Mangum, John S. / Lee, Sang-Jun / Lany, Stephan / Schelhas, Laura T. / Greenaway, Ann L. / Neilson, James R. / Bauers, Sage R. / Andrew, Jennifer S. / Tamboli, Adele C.

2022

Abstract: Magnetic semiconductors may soon improve the energy efficiency of computers, but materials exhibiting these dual properties remain underexplored. Here, we report the computational prediction and realization of a new magnetic and semiconducting material, ... ...

Abstract	Magnetic semiconductors may soon improve the energy efficiency of computers, but materials exhibiting these dual properties remain underexplored. Here, we report the computational prediction and realization of a new magnetic and semiconducting material, MnSnN$_2$, via combinatorial sputtering of thin films. Grazing incidence wide angle X-ray scattering and laboratory X-ray diffraction studies show a wide composition tolerance for this wurtzite-like MnSnN$_2$, ranging from $20\% <$ Mn/(Mn+Sn) $< 65$\% with cation disorder across this composition space. Magnetic susceptibility measurements reveal a low-temperature transition ($T^{\mathrm{*}} \approx 10$ K) for MnSnN$_2$ and strong antiferromagnetic correlations, although the ordering below this transition may be complex. This finding contrasts with bulk MnSiN$_2$ and MnGeN$_2$, which exhibited antiferromagnetic ordering above 400 K in previous studies. Spectroscopic ellipsometry identifies an optical absorption onset of 1 eV for the experimentally-synthesized phase exhibiting cation disorder, consistent with the computationally-predicted 1.2 eV bandgap for the cation-ordered structure. Electronic conductivity measurements confirm the semiconducting nature of this new phase by showing increasing conductivity with increasing temperature. This work adds to the set of known semiconductors that are paramagnetic at room temperature and will help guide future work targeted at controlling the structure and properties of semiconducting materials that exhibit magnetic behavior.
Keywords	Condensed Matter - Materials Science
Subject code	530
Publishing date	2022-06-07
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Electrochemical and in situ ATR-SEIRAS investigations of methanol and CO electro-oxidation on PVP-free cubic and octahedral/tetrahedral Pt nanoparticles

Levendorf, Augusta M / Chen, De-Jun / Liu, Yangwei / Rom, Christopher L / Tong, YuYe J

RSC advances. 2014 May 15, v. 4, no. 41

2014

Abstract: Most wet-chemical methods that synthesize metal nanoparticles (NPs) of a particular size and desired shape include the use of a stabilizing surfactant, such as poly(vinylpyrrolidone) (PVP). The latter has the ability to prohibit and/or promote surface ... ...

Abstract	Most wet-chemical methods that synthesize metal nanoparticles (NPs) of a particular size and desired shape include the use of a stabilizing surfactant, such as poly(vinylpyrrolidone) (PVP). The latter has the ability to prohibit and/or promote surface sites from participating in electrocatalytic reactions, i.e. the methanol oxidation reaction (MOR). In light of our recent findings that adsorbed PVP can enhance the MOR on Pt NPs, a strong effort was made herein to separate the NP surface orientation effect from that of surface-bound PVP. We report the in situ ATR-SEIRAS (attenuated total reflection-surface enhanced infrared reflection absorption spectroscopy) and electrochemical (EC) studies of MOR and CO oxidation reaction (COR) performed on PVP-free cubic and octahedral/tetrahedral (O/T) Pt NPs that were obtained using an adapted liquid phase UV photo-oxidation (UVPO) technique. Transmission electron microscope (TEM) images showed no observable changes of shape and size after the elimination of the PVP, while the integrity of the atomic surface structure was further confirmed by the orientation-dependent EC stripping analysis of irreversibly adsorbed adatoms, i.e. Bi and Ge. The MOR activity was enhanced by the preferential surface orientation of the O/T Pt NPs compared to commercial Pt black and the cubic Pt NPs. The in situ ATR-SEIRAS measurements showed that the PVP-free Pt NPs adsorbed more bridge-bound gaseous CO than those with residual PVP and the weakly hydrogen-bound interfacial water played an important role for the orientation dependent enhancement in MOR activity. Additionally, the findings of this work are coupled with previously published investigations regarding the influence that PVP exerts on the ultimate activity of the Pt NPs, i.e., the adsorbed PVP enhances further the MOR activity on the O/T but suppresses it on the cubic Pt NPs.
Keywords	bismuth ; carbon monoxide ; catalytic activity ; electrochemistry ; methanol ; nanoparticles ; photooxidation ; platinum ; surfactants
Language	English
Dates of publication	2014-0515
Size	p. 21284-21293.
Publishing place	The Royal Society of Chemistry
Document type	Article
ISSN	2046-2069
DOI	10.1039/c4ra00815d
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Solution and Solid State Structural Chemistry of Th(IV) and U(IV) 4-Hydroxybenzoates.

Vanagas, Nicole A / Wacker, Jennifer N / Rom, Christopher L / Glass, Elliot N / Colliard, Ian / Qiao, Yusen / Bertke, Jeffery A / Van Keuren, Edward / Schelter, Eric J / Nyman, May / Knope, Karah E

Inorganic chemistry

2018 Volume 57, Issue 12, Page(s) 7259–7269

Abstract: Organic ligands with carboxylate functionalities have been shown to affect the solubility, speciation, and overall chemical behavior of tetravalent metal ions. While many reports have focused on actinide complexation by relatively simple monocarboxylates ...

Abstract	Organic ligands with carboxylate functionalities have been shown to affect the solubility, speciation, and overall chemical behavior of tetravalent metal ions. While many reports have focused on actinide complexation by relatively simple monocarboxylates such as amino acids, in this work we examined Th(IV) and U(IV) complexation by 4-hydroxybenzoic acid in water with the aim of understanding the impact that the organic backbone has on the solution and solid state structural chemistry of thorium(IV) and uranium(IV) complexes. Two compounds of the general formula [An
Language	English
Publishing date	2018-06-18
Publishing country	United States
Document type	Journal Article
ZDB-ID	1484438-2
ISSN	1520-510X ; 0020-1669
ISSN (online)	1520-510X
ISSN	0020-1669
DOI	10.1021/acs.inorgchem.8b00919
Database	MEDical Literature Analysis and Retrieval System OnLINE

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