<i>Ab initio</i>study of the hygroscopic properties of borate crystals

Lin, Zheshuai; Xu, Liangxiong; Li, R. K.; Wang, Zhizhong; Chen, Chuangtian; Lee, Ming-Hsien; Wang, E. G.; Wang, Dingsheng

doi:10.1103/physrevb.70.233104

Cited by 30 publications

(15 citation statements)

References 17 publications

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“…Comparison of the theoretical (at 0 K) and experimental (at 300 K) equations of state: (a) Fe 3 C cementite, in comparison with high-pressure data of Scott et al [ 19] and Sata et al [ 22]; (b) P6 3 mc-Fe 7 C 3 , in comparison with high-pressure data of Nakajima et al [ 23]; (c) rocksalt-type FeH, in comparison with high-pressure data of Narygina et al [ 46] for the same phase, and of Hirao et al [ 37] for the related dhcp-FeH phase. Theoretical data are for the nonmagnetic state, which has been shown to be stable above 67 GPa for Fe 7 C 3 [ 29] and above 60 GPa [ 20] or 25 GPa [ 21] for Fe 3 C, for FeH at 22 GPa [Error! Reference source not found.]…”

Section: Methodsmentioning

confidence: 99%

“…Using ab initio simulations, Vocadlo et al [ 20] found that collapse of magnetism at ~60 GPa has a major effect on the equation of state of cementite. The magnetic collapse was experimentally observed [ 21] at ~45 GPa; the observation of a large increase of incompressibility lead to the conclusion that the presence of carbon will not improve the match with the observed seismic properties of the inner core. Based on their analysis of the thermal equation of state of Fe 3 C and Fe, Huang et al [ 15] concluded that carbon cannot be a major element of the core.…”

Section: Introductionmentioning

confidence: 96%

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Fe–C and Fe–H systems at pressures of the Earth's inner core

Bazhanova¹,

Oganov²,

Gianola³

2012

Phys.-Usp.

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The solid inner core of the Earth is predominantly composed of iron alloyed with several percent Ni and some lighter elements, Si, S, O, H, and C being the prime candidates. To establish the chemical composition of the inner core it is necessary to find the range of compositions that can explain its observed characteristics. Recently, there have been a growing number of papers investigating C and H as possible light elements in the core, but the results are contradictory. Here, using ab initio simulations, we study the Fe-C and Fe-H systems at inner core pressures (330-364 GPa). Using the evolutionary structure prediction algorithm USPEX, we have determined the lowest-enthalpy structures of possible carbides (FeC, Fe 2 C, Fe 3 C, Fe 4 C, FeC 2 , FeC 3 , FeC 4 and Fe 7 C 3 ) and hydrides (Fe 4 H, Fe 3 H, Fe 2 H, FeH, FeH 2 , FeH 3 , FeH 4 ) and have found that Fe 2 C (space group Pnma) is the most stable iron carbide at pressures of the inner core, while FeH, FeH 3 and FeH 4 are stable iron hydrides at these conditions. For Fe 3 C, the cementite structure (space group Pnma) and the Cmcm structure recently found by random sampling are less stable than the I-4 and C2/m structures found here. We have found that FeH 3 and FeH 4 adopt chemically interesting thermodynamically stable structures, in both compounds containing trivalent iron. We find that the density of the inner core can be matched with a reasonable concentration of carbon, 11-15 mol % (2.6-3.7 wt. %) at relevant pressures and temperatures. This concentration matches that in CI carbonaceous chondrites and corresponds to the average atomic mass in the range 49.3-51.0, in close agreement with inferences from the Birch's law for the inner core. Similarly made estimates for the maximum hydrogen content are unrealistically high, 17-22 mol.% (0.4-0.5 wt. %), which corresponds to the average atomic mass in the range 43.8-46.5. We conclude that carbon is a better candidate light alloying element than hydrogen.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Fe–C and Fe–H systems at pressures of the Earth's inner core

Bazhanova¹,

Oganov²,

Gianola³

2012

Phys.-Usp.

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“…Therefore, we decided to place the nonlinear crystal within an external optical resonator. As a nonlinear material, we chose lithium triborate (LBO) because it can be noncritically phase matched and is expected to be nonhygroscopic [13]. Noncritical phase matching is beneficial because it avoids a walk-off angle between the fundamental and harmonic waves, which tends to distort the harmonic beam shape [14] and limits the interaction length.…”

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confidence: 99%

Continuous-wave single-frequency 532 nm laser source emitting 130 W into the fundamental transversal mode

2010

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The nonlinear effect of second-harmonic generation is an efficient way to realize high-power green laser sources. But when scaling up the harmonic power, many setups reported in the literature have been limited by conversion efficiency degradation or the fundamental laser power. Here we report on the generation of 134 W of cw laser light at a wavelength of 532 nm from a fundamental power of 149 W by second-harmonic generation in an external optical resonator comprising a lithium triborate crystal. The external conversion efficiency was 90%. The harmonic light consisted of a single spectral line. At least 97% of it was emitted into the fundamental transversal mode.

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“…So till now this crystal is the most suitable for the fourth and fifth harmonic generation of Ndbased lasers at 266 and 213 nm [47,50]. On the other hand, even though CLBO can produce much more power output at these UV wavelengths (see Section 3.2.3), the applications of the crystal, such as in micromachining, are hampered by its poor physical chemistry stability, that is, this crystal is very easily crashed by absorbing the water vapor [51]. Although BBO has the largest d eff coefficients for second and third harmonic generation of Nd(Yb)-based lasers, this crystal is not suitable to be applied in these spectrum ranges because of the too large walk-off angles and too small bandwidth compared to the LBO crystal (see Table 3.10).…”

Section: Major Applicationsmentioning

confidence: 99%

Borate Nonlinear Optical Crystals for Frequency Conversion

2012

Nonlinear Optical Borate Crystals

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After the discovery of BBO and LBO during 1979-1987, many research groups are involved in this field because the borate NLO crystals have several outstanding advantages, such as the relative larger second harmonic generation (SHG) coefficients, wide transparent spectral range on the UV side, high damage threshold, and so on. As a result, more than 20 borate NLO crystals have been discovered till now. In this chapter, we will introduce several typical borate crystals, which have indicated important applications, particularly in laser industry. These borate crystals include (1) b-BaB 2 O 4 (BBO), the basic structural unit of which is (B 3 O 6 ) 3À group. (2) LiB 3 O 5 (LBO) family, including CsB 3 O 5 (CBO) and CsLiB 6 O 10 (CLBO), the basic structural unit of which is (

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Ab initiostudy of the hygroscopic properties of borate crystals

Cited by 30 publications

References 17 publications

Fe–C and Fe–H systems at pressures of the Earth's inner core

Fe–C and Fe–H systems at pressures of the Earth's inner core

Continuous-wave single-frequency 532 nm laser source emitting 130 W into the fundamental transversal mode

Borate Nonlinear Optical Crystals for Frequency Conversion

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