Fluorine bomb calorimetry. Enthalpies of formation of the diborides of ziconium and hafnium

Johnson, Gerald K.; Greenberg, Elliott; Margrave, John L.; Hubbard, Ward N.

doi:10.1021/je60032a044

Cited by 19 publications

(9 citation statements)

References 16 publications

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“…The calculated values are given for the ground state structure and also for the nearest metastable structure. In the whole, there is an agreement between the experimental and the calculated values and we can emphasize the nice agreement with the calorimetric values of the Kleppa's group [45,48,49,[57][58][59][60][61]64]. This agreement is very good for diborides of transition metals of Ti and V columns.…”

Section: Resultssupporting

confidence: 79%

Enthalpies of Formation of Transition Metal Diborides: A First Principles Study

Colinet

Tedenac

2015

Crystals

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Abstract:The enthalpies of formation of transition metals diborides in various structures have been obtained from density functional theory (DFT) calculations in order to determine the ground state at T = 0 K and p = 0. The evolution of the enthalpies of formation along the 3D, 4D, and 5D series has been correlated to the considered crystal structures. In the whole, the calculated values of the enthalpies of formation of the diborides in their ground state are in good agreement with the experimental ones when available. The calculated values of the lattice parameters at T = 0 K of the ground state agree well with the experimental values. The total and partial electronic densities of states have been computed. Special features of the transition metal electronic partial density of states have been evidenced and correlated to the local environment of the atoms.

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Section: Resultssupporting

confidence: 79%

Enthalpies of Formation of Transition Metal Diborides: A First Principles Study

Colinet

Tedenac

2015

Crystals

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“…-323 T 7 [40] 35.9 T 0.1 [40] 3244 [43] ZrN -342 [44] 38.9 T 0.2 [37] 2955 T 30 [41] ZrO2 -1101 T 1 [37] 50.4 T 0.4 [37] 2710 [45] HfC -208 T 8 [37] 40.1 T 0.2 [37] 3982 T 30 [42] HfB2 -329 T 9 [46] 42.6 [37] 3378 T 20 [22] HfN -374 T 2 [37] 45 T 1 [37] 3330 T 50 [41] HfO2 -1118 T 2 [37] 59.3 T 0.6 [37] 2800 [45] TaC -142 T 3 [37] 42.3 T 0.2 [37] 4003 T 30 [42] An interesting topic are mixtures of metal carbides forming UHTCs. Not only is the enthalpy of mixing relevant to stability of phases, but also a potential mixing entropy among the metal cations.…”

Section: Zrb2mentioning

confidence: 99%

Polymer‐Derived Ultra‐High Temperature Ceramics (UHTCs) and Related Materials

et al. 2019

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Ultra‐high temperature ceramics (UHTCs) represent an emerging class of materials capable of providing mechanical stability and heat dissipation upon operation in extreme environments, e.g., extreme heat fluxes, chemically reactive plasma conditions. In the last few decades, remarkable research efforts and progress were done concerning the physical properties of UHTCs as well as their processing. Moreover, there are vivid research activities related to developing synthetic access pathways to UHTCs and related materials with high purity, tunable composition, nano‐scaled morphology, or improved sinterability. Among them, synthesis methods considering preceramic polymers as suitable precursors to UHTCs have received increased attention in the last few years. As these synthesis techniques allow the processing of UHTCs from the liquid phase, they are highly interesting, e.g., for the fabrication of ultra‐high temperature ceramic composites (UHT CMCs), additive manufacturing of UHTCs, etc. In the present review, UHTCs are in particular discussed within the context of their physical properties as well as energetics. Moreover, various synthesis methods using preceramic polymers to access UHTCs and related materials (i.e., (nano)composites thereof with silica former phases) are summarized and critically evaluated.

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“…[18][19][20][21][22][23]. In addition, Rogl and Potter [5] reported their calculated enthalpy of formation for ZrB 2 .…”

Section: B-zr Systemmentioning

confidence: 99%