CaB6 single crystals grown under high pressure and hightemperature

Xin, Shengwei; Han, Xianyue; Liu, Shaocun; Liu, Zhongyuan; Xu, Bin; Tian, Yongjun

doi:10.1016/j.jcrysgro.2010.09.067

Cited by 11 publications

(8 citation statements)

References 16 publications

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“…A declining trend with decreasing temperature was observed in the   (T) curve of (4N)CaB 6 ; this obvious discrepancy may have been caused by the impurities introduced by the (4N)B powder. The results of (4N)CaB 6 are similar to those of FZ CaB 6 crystals reported by Terashima et al [25], which has been discussed in [23].…”

Section: Resultssupporting

confidence: 88%

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Properties of CaB6 single crystals synthesized under high pressure and temperature

Xin

Liu

Zhao

et al. 2011

Sci. China Phys. Mech. Astron.

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Pure CaB 6 single crystals are synthesized under high pressure (1 GPa) and temperature (1050°C). The temperature-dependence of electric resistivity and Hall coefficient from 2 to 300 K shows that the CaB 6 single crystals are conductors with semi-metallic behavior and electron carriers. Band structure calculations indicate that the conduction and valence bands meet at the X point at the Fermi level, which is consistent with the experimentally determined conducting behavior of CaB 6 single crystals. Calculations of state density suggest that the states at the Fermi level originate from the 2p orbital of the B atoms and the 3d orbital of the Ca atom. Magnetization measurements show the paramagnetic nature of the CaB 6 . The micro-hardness of CaB 6 is 24.39 GPa, and the Raman spectra of CaB 6 yield three sharp peaks at around 780.9, 1138.9, and 1282.1 cm −1 for T 2g , E g , and A 1g , respectively. The specific heat of the crystal is measured and found to be well described by the Debye and Einstein combined model. The fitting results show Debye and Einstein temperatures are 1119 and 199 K, respectively. high pressure, CaB 6 , semi-metallic, single crystals PACS: 75.40.-s, 72.15.-v, 78.30.-j

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Section: Resultssupporting

confidence: 88%

“…Compared with the flux and floating zone methods, the HP-HT method can synthesize CaB 6 crystals through only the direct reaction of pure B and Ca, yielding cleaner crystals. CaB 6 single crystals obtained from this method were studied in detail in terms of their crystal structure and mechanism of growth [23].…”

Section: Introductionmentioning

confidence: 99%

Properties of CaB6 single crystals synthesized under high pressure and temperature

Xin

Liu

Zhao

et al. 2011

Sci. China Phys. Mech. Astron.

Self Cite

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“…The techniques/methodologies used to date for the CaB 6 powder synthesis include mainly, direct elemental reaction, 12) borothermal or borocarbide reduction, 13)19) mechanochemical treatment or combustion assisted metallothermic reduction, 3), 20) solution-based processing, 21)23) molten salt electrolysis, 10),24), 25) floating zone method, 26) and aluminum flux method. 4) Unfortunately, these techniques suffer from at least one of the following drawbacks: use of expensive and/or hazardous raw materials/ precursors (e.g., elemental boron, calcium and NaBH 4 ), requirement of specialty equipment/reaction vessels and high processing temperature/pressure, and/or long processing time, heavy agglomeration and poor purity of final products, and high overall production cost.…”

Section: )11)mentioning

confidence: 99%

Low-temperature synthesis of calcium hexaboride nanoparticles via magnesiothermic reduction in molten salt

Bao

Lin

Hong

et al. 2017

J. Ceram. Soc. Japan

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Calcium hexaboride (CaB 6 ) nanoparticles were prepared via low temperature magnesiothermic reduction of CaO and B 2 O 3 in molten NaCl, KCl or CaCl 2 . The effects of salt type, Mg amount, and firing temperature and time on the reaction extents were examined, and the responsible reaction mechanisms were discussed. Under an identical firing condition, CaCl 2 facilitated the overall synthesis more effectively than the other two salts. In the case of using 20 mol % excessive Mg, phase-pure CaB 6 nanoparticles of ³50 nm were formed in CaCl 2 after 6 h at 800°C. The "dissolution-precipitation" mechanism is believed to be responsible for the molten salt synthesis of high quality nanosized CaB 6 particles at such a low temperature.

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“…The boride compounds display excellent properties of hardness, strength, and chemical stability because of their structural characteristics. Due to the discovery of the superconductivity of MgB 2 [1], the alkaline earth metal borides have been of great concern [1,2,3,4,5]. As an important member of the alkaline earth metal boride, the calcium boron systems are mentioned by many scientists [2,3,4,5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Due to the discovery of the superconductivity of MgB 2 [1], the alkaline earth metal borides have been of great concern [1,2,3,4,5]. As an important member of the alkaline earth metal boride, the calcium boron systems are mentioned by many scientists [2,3,4,5,6]. Tian et al [2] successfully synthesized CaB 4 crystals under high-temperature high-pressure (HPHT) conditions and pointed out a potential synthesis method for the CaB 2 crystal.…”

Section: Introductionmentioning

confidence: 99%

The Studies on Structure and Stability of CaBn Clusters

et al. 2019

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Calcium-boron systems have excellent properties of hardness, strength, and chemical stability, and we studied a series of CaBn clusters to investigate their structures and relative stability. The results showed the most stable structures of CaBn clusters are not planar. The B atoms tend to get together and form the planar ring to stabilize the structure, and the Ca atoms are coordinated to the periphery of the formations. The average binding energy (Eb), fragmentation energy (EF), second-order energy difference (Δ2E), adiabatic detachment energy (ADE), and adiabatic electron affinity (AEA) of the CaBn clusters were calculated to investigate the relative stability and the ability of removing or obtaining an electron. As shown by the results, EF and Δ2E values had obvious odd-even alteration as n increased, which indicated that the formations CaB4, CaB6, and CaB8 were more stable. The ADE values for CaBn clusters with even values of n were higher than those with odd values of n, which indicated CaBn clusters with even values of n had difficultly removing an electron. The AEA values of CaB3 and CaB7 were larger than the others, which meant CaB3 and CaB7 easily obtained an electron. These results provide a useful reference for understanding the formation mechanism and stability of the alkaline earth metal boride as well as guidance for synthesizing the CaBn clusters.

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CaB6 single crystals grown under high pressure and hightemperature

Cited by 11 publications

References 16 publications

Properties of CaB6 single crystals synthesized under high pressure and temperature

Properties of CaB6 single crystals synthesized under high pressure and temperature

Low-temperature synthesis of calcium hexaboride nanoparticles via magnesiothermic reduction in molten salt

The Studies on Structure and Stability of CaBn Clusters

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