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@article{faucris.111171544,
abstract = {The first gallium-containing nitridosilicate CaGaSiN was synthesized in newly developed high-pressure autoclaves using supercritical ammonia as solvent and nitriding agent. The reaction was conducted in an ammonobasic environment starting from intermetallic CaGaSi with NaN as a mineralizer. At 770 K, intermediate compounds were obtained, which were subsequently converted to the crystalline nitride at temperatures up to 1070 K (70–150 MPa). The impact of other mineralizers (e.g., LiN, KN, and CsN) on the product formation was investigated as well. The crystal structure of CaGaSiN was analyzed by powder X-ray diffraction and refined by the Rietveld method. The structural results were further corroborated by transmission electron microscopy, Si MAS-NMR, and first-principle DFT calculations. CaGaSiN crystallizes in the orthorhombic space group Cmc2 (no. 36) with lattice parameters a=9.8855(11), b=5.6595(1), c=5.0810(1) Å, (Z=4, R=0.0326), and is isostructural with CaAlSiN (CASN). Eu doped samples exhibit red luminescence with an emission maximum of 620 nm and FWHM of 90 nm. Thus, CaGaSiN:Eu also represents an interesting candidate as a red-emitting material in phosphor-converted light-emitting diodes (pc-LEDs). In addition to the already known substitution of alkaline-earth metals in (Ca,Sr)AlSiN:Eu, inclusion of Ga is a further and promising perspective for luminescence tuning of widely used red-emitting CASN type materials.},
author = {Haeusler, Jonas and Neudert, Lukas and Mallmann, Mathias and Niklaus, Robin and Kimmel, Anna-Carina and Alt, Nicolas and Schlücker, Eberhard and Oeckler, Oliver and Schnick, Wolfgang},
doi = {10.1002/chem.201605344},
faupublication = {no},
journal = {Chemistry - A European Journal},
keywords = {ammonothermal synthesis; electron diffraction; luminescence; nitrides; nitridosilicates},
pages = {2583-2590},
peerreviewed = {unknown},
title = {{Ammonothermal} {Synthesis} of {Novel} {Nitrides}: {Case} {Study} on {CaGaSiN3}},
volume = {23},
year = {2017}
}
@inproceedings{faucris.109546844,
author = {Kimmel, Anna-Carina and Hertweck, Benjamin and Steigerwald, Thomas and Alt, Nicolas and Schlücker, Eberhard},
booktitle = {IWBNS-IX},
date = {2015-11-02/2015-11-06},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Applicability} and {Corrosion} {Behavior} of {Different} {Nickel} and {Cobalt} {Based} {Superalloys} in {Ammonoacidic} {Crystal} {Growth} {Process}},
venue = {Wonju},
year = {2015}
}
@article{faucris.121862004,
abstract = {The ammonoacidic crystal growth allows industrial production of bulk semiconductor materials like gallium nitride as a widely known material for applications in photonics. A limitation of this process is strong corrosion of the growth autoclave which consequently leads to high impurity density in grown crystals, even if the autoclave is partly lined with state-of-the-art systems. Innovative metallic liner technologies are evaluated which allow a complete lining of the autoclave and peripheral parts. In this way, bridging the gap between fundamental research regarding the corrosive degeneration of possible liner materials and the implementation of novel lined autoclaves for improved growth conditions. Screening tests to find suitable materials and evaluate its potential for development of a liner technology are described.},
author = {Steigerwald, Thomas and Alt, Nicolas and Hertweck, Benjamin and Niewa, Rainer and Schlücker, Eberhard and Zhang, Shiyu},
doi = {10.1002/ceat.201400414},
faupublication = {yes},
journal = {Chemical Engineering & Technology},
keywords = {Ammonothermal crystal growth; High-pressure equipment; High-temperature coatings; Metallic liner technology},
pages = {1835-1844},
peerreviewed = {unknown},
title = {{Applicability} of metals as liner materials for ammonoacidic crystal growth},
volume = {37},
year = {2014}
}
@article{faucris.113963124,
abstract = {The ammonoacidic crystal growth is a comprehensive method for the synthesis of novel compounds like nitrides or amindes but also for the growth of bulk single crystals like gallium or aluminum nitride for power electronics and photonics. In this report we describe a novel liner technology for growth autoclaves, showing high potential for several research purposes. Thereby the applicability of several ceramic materials as liner materials was investigated for the first time. Moreover, the effectivity of the new apparatus was verified in experimental studies. The described concept based on a silicon nitride crucible is characterized by low costs and diverse possible applications. For example its use is of advantage in fundamental research to explore new nitride materials. Furthermore, it shows high potential for X-ray imaging to investigate basic principles in growth of gallium nitride.},
author = {Hertweck, Benjamin and Schimmel, Saskia and Steigerwald, Thomas and Alt, Nicolas and Wellmann, Peter and Schlücker, Eberhard},
doi = {10.1016/j.supflu.2015.01.017},
faupublication = {yes},
journal = {Journal of Supercritical Fluids},
keywords = {Ammonothermal crystal growth; Liner technology; Ceramic materials; Corrosion; Supercritical ammonia; in situ X-ray imaging},
pages = {76-87},
peerreviewed = {Yes},
title = {{Ceramic} liner technology for ammonoacidic synthesis},
volume = {99},
year = {2015}
}
@inproceedings{faucris.281272971,
author = {Schimmel, Saskia and Meisel, Magnus and Hertweck, Benjamin and Steigerwald, Thomas and Nebel, Christoph and Alt, Nicolas and Schlücker, Eberhard and Wellmann, Peter},
booktitle = {5th German-Swiss Conference on Crystal Growth},
date = {2017-03-08/2017-03-10},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Chemical} stability of carbon-based inorganic construction materials for in situ x-ray measurements of ammonothermal crystal growth of nitrides},
venue = {Freiburg},
year = {2017}
}
@article{faucris.106920044,
abstract = {The chemical stability of diamond, silicon carbide, vitreous carbon, and boron carbide in supercritical ammonia containing different mineralizers was investigated. The materials were found to show good corrosion resistance in the presence of selective or all tested mineralizers.Diamond was found to be virtually inert in both ammonoacidic and ammonobasic reaction media.Silicon carbide showed good chemical stability in varying ammonothermal reaction media.The chemical stability of vitreous carbon was found to depend on its manufacturing temperature.Corrosion of boron carbide strongly depends on the mineralizer used as well as on applied mechanical stress.Based on their chemical stability and mechanical properties, the applicability of the materials in the respective ammonothermal reaction media as construction materials is evaluated. Additionally, the applicability of the materials as a window material for both high energy . in situ x-ray imaging and low energy . in situ x-ray diffraction is discussed.},
author = {Schimmel, Saskia and Künecke, Ulrike and Meisel, Magnus and Hertweck, Benjamin and Steigerwald, Thomas and Nebel, Christoph and Alt, Nicolas and Schlücker, Eberhard and Wellmann, Peter},
doi = {10.1016/j.jcrysgro.2016.08.067},
faupublication = {yes},
journal = {Journal of Crystal Growth},
keywords = {A1. Solubility; A1. Solvents; A1. X-ray diffraction; A2. Ammonothermal crystal growth; B1. Inorganic compounds; B1. Nitrides},
pages = {33-42},
peerreviewed = {Yes},
title = {{Chemical} stability of carbon-based inorganic materials for in situ x-ray investigations of ammonothermal crystal growth of nitrides},
volume = {456},
year = {2016}
}
@inproceedings{faucris.109544204,
author = {Kimmel, Anna-Carina and Hertweck, Benjamin and Steigerwald, Thomas and Alt, Nicolas and Schlücker, Eberhard},
booktitle = {EMSF},
date = {2016-05-08/2016-05-11},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Corrosion} {Behaviour} of {Nickel} and {Cobalt} {Based} {Super} {Alloys} in {Supercritical} {Ammonia} {Containing} {Acidic} {Mineralizers} {NH4F} or {NH4Cl}},
venue = {Essen},
year = {2016}
}
@inproceedings{faucris.111233584,
author = {Hertweck, Benjamin and Steigerwald, Thomas and Kimmel, Anna-Carina and Alt, Nicolas and Schlücker, Eberhard},
booktitle = {4th ISHA},
date = {2014-10-26/2017-06-29},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Corrosion} resistance of different superalloys in ammonoacidic environment},
venue = {Bordeaux},
year = {2014}
}
@article{faucris.109512964,
abstract = {The ammonothermal growth of different bulk group III nitride materials enables cost-efficient production of high-quality single crystals. Despite its advantages this process is limited due to the corrosive ammonothermal environment. This environment consists of supercritical ammonia with acidic or basic additives at high temperatures and pressures in high-pressure cells made of a nickel-base alloy. As a consequence of corrosion, large amounts of metallic impurities are detectable in the grown crystals. The mechanisms of corrosion are not well understood. A method is presented to investigate corroded autoclaves, caused by the interaction with supercritical fluid, together with first results regarding the degeneration of autoclave material.},
author = {Steigerwald, Thomas and Alt, Nicolas and Hertweck, Benjamin and Schlücker, Eberhard},
doi = {10.1002/ceat.201300719},
faupublication = {yes},
journal = {Chemical Engineering & Technology},
keywords = {Ammonothermal crystal growth; Autoclaves; High-pressure equipment; High-temperature corrosion; Nickel-base alloy},
pages = {1903-1906},
peerreviewed = {unknown},
title = {{Corrosive} degeneration of autoclaves for the ammonothermal synthesis: {Experimental} approach and first results},
volume = {37},
year = {2014}
}
@article{faucris.111230504,
abstract = {Quantitative data on the solubility of GaN in supercritical ammonia using NH4F as mineralizer are reported. The solubility is determined by in situ x-ray imaging of the dissolution of GaN single crystals. First, solubility values obtained by this method with NH4Cl as mineralizer are presented and discussed with respect to existing literature data Monitoring the dissolution process in situ reveals the time when the solubility limit is reached. Thus, it allows to distinguish the saturation of the solution from dissolution based on mass transport and deposition. This is a key advantage of solubility measurements by in situ x-ray imaging compared to gravimetric methods. Our results indicate that the solubility limit is reached much faster than usually assumed in gravimetric solubility studies and the solubility of GaN in ammonothermal media is significantly lower than reported so far. (C) 2015 Elsevier B.V. All rights reserved.},
author = {Schimmel, Saskia and Lindner, Michael and Steigerwald, Thomas and Hertweck, Benjamin and Richter, Theresia M.M. and Künecke, Ulrike and Alt, Nicolas and Niewa, Rainer and Schlücker, Eberhard and Wellmann, Peter},
doi = {10.1016/j.jcrysgro.2015.02.020},
faupublication = {yes},
journal = {Journal of Crystal Growth},
keywords = {Solubility;Solvents;Mineralizers;Growth from solutions;Ammonothermal crystal growth;Nitrides},
pages = {64-69},
peerreviewed = {Yes},
title = {{Determination} of {GaN} solubility in supercritical ammonia with {NH4F} and {NH4Cl} mineralizer by in situ x-ray imaging of crystal dissolution},
volume = {418},
year = {2015}
}
@article{faucris.109532764,
abstract = {The ammonothermal process is a promising technique for cost-effective growth of nitride based bulk-semiconductors. Degeneration of growth reactors made of a NiFeCr alloy is a limiting factor of the growth process. Corrosion is initiated by supercritical ammonia and acidic as well as basic mineralizer up to 600 °C and 300 MPa. We investigated the corrosion processes with microscopic (optical and scanning electron microscopy) and spectroscopic (energy dispersive X-ray and auger electron spectroscopy) methods. It showed that ammonobasic environments lead to the formation of a nitrited layer. Composition and thickness changes depending on the number of loads. The corrosion layer does not reach a steady state and therefore degenerates as consequence of cyclic ammonothermal loads. For ammonoacidic conditions on the other hand significant general corrosion occurred which is connected to the dissolution of the metal phase in the supercritical. Moreover, a high tendency to stress corrosion cracking was observed.},
author = {Steigerwald, Thomas and Hertweck, Benjamin and Alt, Nicolas and Schlücker, Eberhard},
doi = {10.1016/j.supflu.2014.08.006},
faupublication = {yes},
journal = {Journal of Supercritical Fluids},
keywords = {Ammonothermal crystal growth; Corrosion; Nickel base alloy; Supercritical ammonia},
pages = {158-166},
peerreviewed = {Yes},
title = {{Different} corrosion behaviour of autoclaves made of nickel base alloy 718 in ammonobasic and ammonoacidic environments},
volume = {95},
year = {2014}
}
@article{faucris.109118944,
author = {Fikrt, André and Brehmer, Richard and Milella, Vito-Oronzo and Müller, Karsten and Bösmann, Andreas and Preuster, Patrick and Alt, Nicolas and Schlücker, Eberhard and Wasserscheid, Peter and Arlt, Wolfgang},
doi = {10.1002/201600388},
faupublication = {yes},
journal = {Applied Energy},
peerreviewed = {Yes},
title = {{Dynamic} power supply by hydrogen bound to a liquid organic hydrogen carrier},
year = {2017}
}
@article{faucris.109533424,
abstract = {With an eye on numerical simulations of ammonothermal growth of group III-V bulk single crystals, precise data for viscosity and density are strongly needed. In this work, changes in viscosity depending on temperature and pressure are traced in the developed ball viscometer. There, the falling time is detected by acquiring the acoustic signal of the ball using a high temperature borne-noise acceleration sensor. The results for the viscosity of pure ammonia at ammonothermal conditions already show good accuracy. The apparatus is designed to measure the density in addition to the viscosity, by the substitution of the rolling ball material in later experiments. This is important because the density of the flowing fluid is not constant due to the solubility change of GaN in ammonia by the mineralizers obligatory in ammonothermal process.},
author = {Steigerwald, Thomas and Alt, Nicolas and Hertweck, Benjamin and Schlücker, Eberhard},
doi = {10.1016/j.jcrysgro.2014.06.013},
faupublication = {yes},
journal = {Journal of Crystal Growth},
keywords = {A1. Solvents; Ammonothermal crystal growth; B1. Nitrides; Solubility},
pages = {59-65},
peerreviewed = {Yes},
title = {{Feasibility} of density and viscosity measurements under ammonothermal conditions},
volume = {403},
year = {2014}
}
@inproceedings{faucris.208233995,
author = {Shoshi, Arian and Schaller, Andreas and Freitag, Detlef and Alt, Nicolas and Schlücker, Eberhard},
booktitle = {10th World Congress of Chemical Engineering},
date = {2017-10-01/2017-10-05},
faupublication = {yes},
isbn = {ISBN: 978-84-697-8629-1},
pages = {544},
peerreviewed = {unknown},
title = {{Harvesting} the compression heat energy in high-pressure compressors for the use in processes},
venue = {Barcelona, Spain},
year = {2017}
}
@inproceedings{faucris.281273255,
author = {Schimmel, Saskia and Künecke, Ulrike and Steigerwald, Thomas and Hertweck, Benjamin and Alt, Nicolas and Schlücker, Eberhard and Wellmann, Peter},
booktitle = {German Conference on Crystal Growth},
date = {2014-03-12/2014-03-14},
faupublication = {yes},
peerreviewed = {unknown},
title = {{In} {Situ} {Visualization} of {GaN} {Crystals} in {Ammonothermal} {High} {Pressure} {Autoclaves} by {X}-ray {Imaging}},
venue = {Halle},
year = {2014}
}
@inproceedings{faucris.224756432,
author = {Steger, Daniel and Alt, Nicolas and Schlücker, Eberhard},
booktitle = {Jahrestreffen der ProcessNet-Fachgemeinschaft "Prozess-, Apparate- und Anlagentechnik" (PAAT)},
date = {2016-11-14/2016-11-15},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Modulare} {Pumpensysteme}},
venue = {Karlsruhe},
year = {2016}
}
@article{faucris.121400884,
abstract = {A numerical analysis of an ammonothermal synthesis process for the bulk growth of nitride crystals was performed. The analysis includes the development of a thermal model for a lab-scale ammonothermal autoclave, which was validated by in situ temperature measurements and applied to tailor the temperature field inside the autoclave. Based on the results of the global thermal 2D simulations, a local 3D model was used to include convective phenomena in the analysis. Moreover, the influence of the baffle and different baffle shapes on the flow velocity was investigated. Fluctuations of the temperature as well as the flow velocities occur, indicating that 3D considerations are essential to accurately investigate the heat and mass transport in ammonothermal systems.},
author = {Erlekampf, Jürgen and Seebeck, Jan and Savva, P. and Meissner, Elke and Friedrich, Jochen and Alt, Nicolas and Schlücker, Eberhard and Frey, Lothar},
doi = {10.1016/j.jcrysgro.2014.06.007},
faupublication = {yes},
journal = {Journal of Crystal Growth},
keywords = {A1. 3D CFD; A2. Ammonothermal; B1. Nitrides},
pages = {96-104},
peerreviewed = {Yes},
title = {{Numerical} time-dependent {3D} simulation of flow pattern and heat distribution in an ammonothermal system with various baffle shapes},
volume = {403},
year = {2014}
}
@inproceedings{faucris.224756938,
author = {Steger, Daniel and Weinrich, Abraham and Kögler, Andreas and Alt, Nicolas and Schlücker, Eberhard},
booktitle = {10th World Congress of Chemical Engineering},
date = {2017-10-01/2017-10-05},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Self}-{Adaptive} {Inline}-{Pulsation}-{Damper} for {Positive} {Displacement} {Pumps}},
venue = {Barcelona},
year = {2017}
}
@article{faucris.122188264,
abstract = {Solubility and dissolution kinetics of GaN are investigated, as they represent essential parameters for ammonothermal crystal growth of GaN. In situ X-ray imaging is applied to monitor the dissolving crystal. Both ammonoacidic and ammonobasic conditions are investigated. Compared to NH4F, the dissolution is generally much slower using NaN3 mineralizer, leading to a much longer time needed to establish a saturated solution. The solubility of GaN at 540 °C and 260 MPa in supercritical ammonia with a molar concentration
of NaN3 of 0.72 mmol/ml is determined to be 0.15 ± 0.01 mol%. This suggest a severe
refinement of raw gravimetric literature data also for alkali metal based mineralizers, as we reported previously for ammonium halide mineralizers. The order of magnitude is in good agreement with refined gravimetric solubility data (Griffiths et al., 2016). The apparent discrepancy between the literature and this work regarding the temperature range in which retrograde solubility occurs is discussed. A possible reason for the occurrence of retrograde solubility at high temperatures is described. The paper is complemented by a section pointing out and partially quantifying potential, reactor-material-dependent sources of errors.},
author = {Schimmel, Saskia and Koch, Martina and Macher, Philipp and Kimmel, Anna-Carina and Steigerwald, Thomas and Alt, Nicolas and Schlücker, Eberhard and Wellmann, Peter},
doi = {10.1016/j.jcrysgro.2017.09.027},
faupublication = {yes},
journal = {Journal of Crystal Growth},
keywords = {Solubility; Solvents; Ammonothermal crystal growth; Growth from solutions; Solvothermal crystal growth; Gallium compounds},
pages = {59-66},
peerreviewed = {Yes},
title = {{Solubility} and dissolution kinetics of {GaN} in supercritical ammonia in presence of ammonoacidic and ammonobasic mineralizers},
volume = {479},
year = {2017}
}
@inproceedings{faucris.109520224,
author = {Steigerwald, Thomas and Kimmel, Anna-Carina and Hertweck, Benjamin and Alt, Nicolas and Schlücker, Eberhard},
booktitle = {EMSF},
date = {2016-05-08/2016-05-11},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Solubility} {Studies} of {Gallium} {Nitride} in {Supercritical} {Ammonia} {Containing} {NH4F}},
venue = {Essen},
year = {2016}
}
@article{faucris.120601184,
abstract = {In-situ X-ray visualization of hydrothermal growth of silicalite- 1 is applied as an intermediate step for developing X-ray in-situ visualization techniques for ammonothermal growth of nitride materials. In-situ X-ray imaging of silicalite-1 crystals grown by the bulk material dissolution technique (Shimizu and Hamada, Angew. Chem., Int. Ed. 38, 2725 (1999) [1]) is demonstrated using a stainless steel autoclave equipped with ceramic aluminium oxide windows. Processes in the reaction medium such as local density changes are also visualized. The transferability of the technique to ammonothermal growth of nitrides is evaluated. Furthermore, the applicability of windowless autoclaves for X-ray in-situ monitoring of ammonothermal crystal growth of nitrides is investigated. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim},
author = {Schimmel, Saskia and Künecke, Ulrike and Baser, Hasan-Hüseyin and Steigerwald, Thomas and Hertweck, Benjamin and Alt, Nicolas and Schlücker, Eberhard and Schwieger, Wilhelm and Wellmann, Peter},
doi = {10.1002/pssc.201300656},
faupublication = {yes},
journal = {Physica Status Solidi (C) Current Topics in Solid State Physics},
keywords = {in-situ X-ray imaging;ammonothermal crystal growth;GaN;nitrides},
month = {Jan},
pages = {1439-1442},
peerreviewed = {Yes},
title = {{Towards} {X}-ray in-situ visualization of ammonothermal crystal growth of nitrides},
volume = {11},
year = {2014}
}