Capsule-based combinatorial study of solubility, transport and crystallization for ammonothermal synthesis of piezoelectric and ferroelectric ternary nitrides

Geng C, Wostatek T, Zenk M, Friedrich J, Schimmel S (2026)

Publication Language: English

Publication Type: Conference contribution, Abstract of lecture

Publication year: 2026

Event location: Warsaw, Poland PL

Abstract

Capsule-based combinatorial study of solubility, transport and crystallization for ammonothermal synthesis of piezoelectric and ferroelectric ternary nitrides

C. Geng,1 T. Wostatek,1 M. Zenk,2 J. Friedrich,2 S. Schimmel1

1Friedrich-Alexander-Universität Erlangen-Nürnberg, Chair of Electron Devices (LEB), Erlangen, 91058, Germany. 2Fraunhofer Institute for Integrated Systems and Device Technology IISB, 91058 Erlangen, Germany

email:chongwei.geng@fau.de

Novel ternary metal nitrides, such as III1−xMexN (III = Ga, Al…, Me = Sc, Y, B, Cr…), provide a wide compositional space for piezoelectric and ferroelectric materials. These materials are promising for energy-efficient computing and high-density non-volatile memory devices [1]. For ammonothermal synthesis of such compounds, the dissolution behavior of many potential starting materials, such as BN, AlN, ScN, has not yet been systematically investigated [2]. Solubility depends strongly on the type of mineralizer, temperature, pressure and density of supercritical ammonia [3]. Therefore, a method is needed to investigate several candidate materials efficiently under defined ammonothermal conditions.

This contribution presents a capsule-based combinatorial approach for studying solubility, transport and crystallization in the ammonothermal process. Several small capsules, fabricated from chemically stable metals with low thermal conductivity, such as Inconel 718, are used as individual reaction chambers in an autoclave with a pronounced internal temperature gradient. Numerical simulations performed with CrysMAS, a software developed by Fraunhofer IISB, indicate that a pronounced internal temperature gradient can exist within an Inconel capsule under ammonothermal conditions. Along the capsule centerline, a longitudinal temperature gradient of 17 K/cm obtained from the bottom to the top of the capsule. The simulation results are used to tailor the capsule geometry to establish suitable temperature conditions inside the capsule for ammonothermal experiments. The results of a series of experiments with boron nitride as the boron-containing educt will be reported, including an evaluation of dissolution, material transport, and crystallization under ammonothermal conditions.

The capsule design enables parallel experiments, protects the autoclave from corrosion, reduces educt consumption for saturating the solution, and provides data for selecting suitable material combinations, mineralizers, and temperature conditions for future synthesis of piezoelectric and ferroelectric ternary nitrides.

Reference:

[1] C.-W. Lee, R.W. Smaha, G.L. Brennecka, N.M. Haegel, P. Gorai, K. Yazawa, APL Mater. 13, 021114, 2025.

[2] T. Wostatek, V.Y.M.R. Chirala, Stoddard, N.; Civas, E.N.; Pimputkar, S.; Schimmel, S. Materials 17, 3104, 2024.

[3] T.M.M. Richter, R. Niewa, Inorganics 2, 29–78, 2014.

Acknowledgements: The authors thank the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)–563184897 for funding.

Authors with CRIS profile

Chongwei Geng Lehrstuhl für Elektronische Bauelemente Thomas Wostatek Lehrstuhl für Elektronische Bauelemente Saskia Schimmel Lehrstuhl für Elektronische Bauelemente

Related research project(s)

Tuning piezo- and ferroelectric properties of III-nitrides by alloying with metal nitrides – crystallization from N2- and NH3-based solutions and gas phases guided by atomistic simulations (PiezoTUNE) SPP 2477: Nitrides4Future – Neuartige Materialien und Konzepte für Bauelemente April 15, 2026 - April 14, 2029

Involved external institutions

Fraunhofer-Institut für Integrierte Systeme und Bauelementetechnologie (IISB) DE Germany (DE)

How to cite

APA:

Geng, C., Wostatek, T., Zenk, M., Friedrich, J., & Schimmel, S. (2026, September). Capsule-based combinatorial study of solubility, transport and crystallization for ammonothermal synthesis of piezoelectric and ferroelectric ternary nitrides. Paper presentation at 2026 Fall Meeting & Exhibit of the European Materials Research Society (E-MRS), Warsaw, Poland, PL.

MLA:

Geng, Chongwei, et al. "Capsule-based combinatorial study of solubility, transport and crystallization for ammonothermal synthesis of piezoelectric and ferroelectric ternary nitrides." Presented at 2026 Fall Meeting & Exhibit of the European Materials Research Society (E-MRS), Warsaw, Poland 2026.

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