Mode coupling and the pressure induced phase transition in thallium azide (TlN3)

Christoe, C. W.; Iqbal, Zafar

doi:10.1016/0038-1098(74)90680-2

Cited by 20 publications

(6 citation statements)

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“…Consequently, the T(E g ) mode was softening in the whole process of Phases II and III. Of note, the displacive structural transitions from tetragonal to monoclinic structure in KN 3, RbN 3 , and TlN 3 are all accompanied by the pressure-dependent softening of T(E g ) mode. ,, Furthermore, onsets of these phase transitions and the completions of the T(E g ) softening are simultaneous in these azides. For RbN 3 , the abnormal softening behavior of T(E g ) triggered a displacive I 4/ mcm to C 2/ m transition under pressure .…”

Section: Resultsmentioning

confidence: 92%

“…For KN 3 , RbN 3 , and TlN 3 , isostructural with CsN 3 at ambient conditions, the softening of T(E g ) mode are all related to the shearing distortion of the tetragonal structure upon compression. 14,16,27 Therefore, we infer that the Phase III still possesses the layered structure, similar to that of Phase II, and a shift of layers parallel to the (001) plane is triggered by compression. The distances of the neighbor Cs + ions between the adjacent layers should be increased due to the shearing distortion of the tetragonal structure, which in turn weaken the corresponding translational vibrations.…”

Section: ■ Experimental Sectionmentioning

confidence: 87%

“…Additionally, CsN 3 was found to has a relatively low polymerization pressure compared with LiN 3 , NaN 3 , and KN 3 . Although amount of experimental and theoretical studies about CsN 3 have been carried out, several problems about CsN 3 under pressure are still unsolved: (1) A controversy was currently existed about the structure of phase IV between recent Raman and X-ray diffraction study. , (2) The pressure-induced evolution of T(E g ) mode has been found to trigger structural phase transitions in the tetragonal KN 3 , RbN 3 , and TlN 3 ; ,, however, it was absent in recent high-pressure study of CsN 3 due to the limitation of measuring range . (3) The high-pressure behaviors of NNN bending vibrations of CsN 3 have not yet been conducted so far, which have been found to play a significant role for exploring the evolution of azide ions under pressure. , …”

Section: Introductionmentioning

confidence: 99%

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High-Pressure Raman and Infrared Spectroscopic Studies of Cesium Azide

Zhu

Jiang

et al. 2016

J. Phys. Chem. C

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In this work, we present the effects of high pressure on the structure and stability of cesium azide (CsN 3 ) with the pressure up to ∼30.0 GPa, as studied by Raman and IR spectroscopy. Three phase transitions of Phase II → III → IV → V were revealed at ∼0.5, ∼3.7, and ∼16.0 GPa. The abnormal softening behavior of T(E g ) mode reveals the shearing distortion during Phase II → III transition. Moreover, changes of lattice modes and splitting of the degenerate T(E g ) and R(E g ) modes in Phase III indicate the breaking of crystallographically equivalent condition of azide ions. Phase IV was found to possess the C2/m structure, and Phase V has a lower symmetry structure than other phases. The IR measurements show the evolution of the NNN bending modes and the IR-active behavior of the symmetric stretch ν 1 mode under pressure, which collectively reveal the rotation and bending of the azide ions upon compression. The azide ions groups were found to further bend under pressure, and the bent azide ions might enhance propensity of nitrogen polymerization.

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Section: Resultsmentioning

confidence: 92%

Section: ■ Experimental Sectionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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High-Pressure Raman and Infrared Spectroscopic Studies of Cesium Azide

Zhu

Jiang

et al. 2016

J. Phys. Chem. C

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“…The change from the tetragonal phase II through phase IV, and finally to phase III may be from an eight-fold to a 4-4 coordination with four long azide-metal bonds and four short azide -metal bonds. (") Such 4 -4 coordination has been observed in AgN,, (29) with distortion which is a consequence of weak covalent bonding between the azide and the thallium ions. At higher temperature the thermal energy masks these distortions.…”

Section: Thallium Azidementioning

confidence: 76%

Thermophysics of alkali and related azides II. Heat capacities of potassium, rubidium, cesium, and thallium azides from 5 to 350 K

Carling¹,

Westrum²

1978

The Journal of Chemical Thermodynamics

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The heat capacities of potassium, rubidium, &urn, and thallium azides were determined from 5 to 350 K by adiabatic calorimetry. Although the alkali-metal azides studied in this work exhibited no thermal anomalies over the temperature range studied, thaIlium azide has a bifurcated anomaly with two maxima at (233.0*0.1) K and (242.0410.02) K. The associated excess entropy was 0.90 calth K-l mol-I. The thermal properties of the azides and the corresponding structurally similar hydrogen difluorides are nearly identical. Both have linear symmetrical anions. However, thallium azide shows a solid-solid phase transition not exhibited by thallium hydrogen difluoride. At 298.

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“…However, until recently, high-pressure phase diagrams of azides were studied only in a narrow pressure range below 4 GPa. [11][12][13][14][15][16][17] Discovery of the polymerization of nitrogen at a pressure near 120 GPa (Ref. 18) renewed interest in inorganic azides as a precursor for the synthesis of extended nitrogen allotropic structures at lower pressures, and their pressure-induced phase transitions have been intensively studied over a wide range of pressures, both theoretically and experimentally.…”

Section: Introductionmentioning

confidence: 99%

Phase transitions of cesium azide at pressures up to 30 GPa studied using in situ Raman spectroscopy

Medvedev

Barkalov

Naumov

et al. 2015

Journal of Applied Physics

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Cesium azide has been studied by Raman spectroscopy at pressures up to %30 GPa at room temperature. The sequence of phase transitions to Phase III (at 0.5 GPa), Phase IV (at 4.3 GPa), and Phase V (at %19 GPa) has been observed in agreement with recent X-ray diffraction studies. Phase III has been found to adopt a monoclinic C2/m structure with two azide anions in nonequivalent positions, where one set of azide anions appears to be orientationally disordered according to the observed Raman spectra. The transition to Phase IV has been associated with orientational ordering of azide anions, while the transition to Phase V has been shown to proceed with a lowering of crystal symmetry. Moreover, spectroscopic features indicate a possible change of bonding in CsN 3 toward formation of covalent bonds at high pressures. V

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Mode coupling and the pressure induced phase transition in thallium azide (TlN3)

Cited by 20 publications

References 13 publications

High-Pressure Raman and Infrared Spectroscopic Studies of Cesium Azide

High-Pressure Raman and Infrared Spectroscopic Studies of Cesium Azide

Thermophysics of alkali and related azides II. Heat capacities of potassium, rubidium, cesium, and thallium azides from 5 to 350 K

Phase transitions of cesium azide at pressures up to 30 GPa studied using in situ Raman spectroscopy

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