Thermodynamic properties and electrical conductivity of Ta3N5 and TaON

Swisher, J. H.; Read, M. H.

doi:10.1007/bf02642054

Cited by 17 publications

(26 citation statements)

References 4 publications

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“…For example, rounded pores are found in dealloyed Ag–Au, whereas striking aligned faceting was found in single crystal MnO films produced by reduction of ZnMn 2 O 4 in forming gas . The shape of the pores is expected to be a function of the surface diffusion rates and the difference of those rates on different facets of the product crystalline structure …”

Section: Resultsmentioning

confidence: 99%

Mesoporous Metal Nitride Materials Prepared from Bulk Oxides

et al. 2012

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International audienceThe preparation of metal nitride materials structured on the nano or mesoscale is challenging due to the need for high sintering temperatures and/or long reaction times. Here, we present a new and simple process for preparing mesoporous transition metal nitrides without the use of nanopatterning or other templating. Mesoporous VN, TiN, CrN, Ta3N5, TaN, NbN, WN, MoN, and Mo2N are obtained by the ammonolysis of bulk ternary oxides containing Zn. The products were characterized by Rietveld refinement of powder X-ray diffraction (PXRD) patterns, scanning electron microscopy (SEM), and nitrogen adsorption/desorption analysis. Our results demonstrate that the pore sizes of these materials range from 10 to 50 nm. By varying the precursor stoichiometry, the transition metal, and processing conditions, many different mesoporous morphologies are obtained. These materials show high surface area and good electrical conductivity

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Section: Resultsmentioning

confidence: 99%

Mesoporous Metal Nitride Materials Prepared from Bulk Oxides

et al. 2012

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“…For example, in our previous work we were unable to form single phase β-TaON thin films in either wet or dry ammonia. 27,36 Moreover, while a significant amount of literature is available on its crystal and electronic structure, 28,29,30,31 and photoelectrochemical performance, 8,10 to date a quantitative analysis of the carrier mobility and lifetime of β-TaON is missing.…”

Section: Introductionmentioning

confidence: 98%

“…(a) Ta-O-N phase diagram after Swisher at al.,28 indicating the region explored in this work. (b) In-situ optical monitoring of the stepwise nitridation of a Ta 2 O 5 thin film.…”

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confidence: 99%

Oxynitrogenography: Controlled Synthesis of Single-Phase Tantalum Oxynitride Photoabsorbers

Respinis¹,

Fravventura

Abdi

et al. 2015

Chem. Mater.

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We propose an in-situ UV-vis monitoring technique called 'oxynitrogenography' as an approach towards the controlled and reproducible synthesis of thin films of different Ta-O-N phases, including the elusive β-TaON phase. The optical absorption changes are measured during annealing of the film at increasing NH 3 /H 2 O ratios, and can be directly correlated to the presence of different phases (Ta 2 O 5 , β-TaON, mixed TaON-Ta 3 N 5 , Ta 3 N 5 ) due to the abrupt change in the absorption edge. After additional XRD analysis, the thermodynamic equilibrium conditions to obtain these various phases are determined, and a phase diagram is constructed. We observe that there is a very narrow range of parameters for the thermodynamic stability of the β-TaON phase. We observe that the carrier mobility increases with the nitrogen content in the sample, from 10 -5 cm 2 /Vs in Ta 2 O 5 , to 10 -2 cm 2 /Vs in β-TaON and the mixed TaON-Ta 3 N 5 , until 10 -1 cm 2 /Vs in Ta 3 N 5 . While the carrier mobility of β-TaON and Ta 3 N 5 is comparable to that of BiVO 4 , the lifetime in the order of milliseconds is comparable to that of crystalline silicon. This is much higher than previously reported and compares favorably with the currently most promising metal oxide-based semiconductors (BiVO 4 , Fe 2 O 3 , WO 3 , Cu 2 O) for photo-electrochemical (PEC) water splitting. Although these long lifetimes may be partly caused by (de-)trapping from shallow trap states, these results clearly demonstrate that a high phase purity is an essential prerequisite for efficient (oxy)nitride-based absorber materials.

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“…On the other hand above 1200°C, some oxidation of the TaON was observed. Similar observations were made during heat treatment of the powder indicating the relatively low thermal stability of the TaON phase at high temperatures 15 . The mechanical properties were therefore only determined for the materials densified using the high‐pressure technique.…”

Section: Discussionmentioning

confidence: 63%

“…Similar observations were made during heat treatment of the powder indicating the relatively low thermal stability of the TaON phase at high temperatures. 15 The mechanical properties were therefore only determined for the materials densified using the high-pressure technique. With an increase in the densification temperature from 9201 to 11001C, a slight increase in the hardness and the K IC values was observed.…”

Section: Discussionmentioning

confidence: 99%

Preparation, Hardness, and Fracture Toughness of Tantalum Oxynitride Ceramics

Matizamhuka

Herrmann

Sigalas

et al. 2007

Journal of the American Ceramic Society

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Tantalum oxynitride powder with a baddeleyite crystal structure was synthesized and densified by hot pressing in Ar and under high pressure using a belt‐type high‐pressure apparatus. The tantalum oxynitride powder could not be densified completely under hot‐pressing conditions at 1400°C. The use of high pressure resulted in dense materials. The samples showed a hardness of 16–17 GPa and a fracture toughness of 3–4 MPa·m1/2. The hardness is higher compared with that of ZrO2 and HfO2 ceramics. The fracture toughness corresponds to the value of fully stabilized ZrO2 due to the absence of any transformation toughening mechanism.

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Thermodynamic properties and electrical conductivity of Ta3N5 and TaON

Cited by 17 publications

References 4 publications

Mesoporous Metal Nitride Materials Prepared from Bulk Oxides

Mesoporous Metal Nitride Materials Prepared from Bulk Oxides

Oxynitrogenography: Controlled Synthesis of Single-Phase Tantalum Oxynitride Photoabsorbers

Preparation, Hardness, and Fracture Toughness of Tantalum Oxynitride Ceramics

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