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Anomalous melting behavior of polycrystalline bismuth quenched at high temperature and high pressure
Author’s Accepted Manuscript Anomalous melting behavior of polycrystalline bismuth quenched at high temperature and high pressure Yu Shu, Wentao Hu, Zhisheng Zhao, Limin Wang, Zhongyuan Liu, Yongjun Tian, Dongli Yu www.elsevier.com
PII: DOI: Reference:
S0167-577X(15)31018-1 http://dx.doi.org/10.1016/j.matlet.2015.12.065 MLBLUE20025
To appear in: Materials Letters Received date: 13 November 2015 Accepted date: 14 December 2015 Cite this article as: Yu Shu, Wentao Hu, Zhisheng Zhao, Limin Wang, Zhongyuan Liu, Yongjun Tian and Dongli Yu, Anomalous melting behavior of polycrystalline bismuth quenched at high temperature and high pressure, Materials Letters, http://dx.doi.org/10.1016/j.matlet.2015.12.065 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Anomalous melting behavior of polycrystalline bismuth quenched at high temperature and high pressure Yu Shu, Wentao Hu, Zhisheng Zhao, Limin Wang, Zhongyuan Liu, Yongjun Tian, and Dongli Yu* State Key Lab of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China
Abstract Under ambient conditions, bismuth (Bi) adopts a rhombohedral A7 structure, yet Bi treated at high temperature and high pressure (HTHP) has been proven to have derivative structural polytypes that coexist with the common A7 structure. This paper studies the melting behavior of HTHP-treated polycrystalline Bi using differential scanning calorimetry (DSC) and in situ transmission electron microscopy (TEM) measurements. The Bi samples quenched at a pressure of 2 GPa and a temperature above 2000℃ show an additional endothermic peak before the common melting peak of A7-Bi in the DSC curves. This is probably due to the high-temperature relaxation of the distorted A7 configuration. The samples maintain their initial morphology characteristics during repeated heating cycles, indicating the incomplete melting of distorted Bi polytypes. Keyword: Bismuth, thermal properties, electron microscopy, deformation, high temperature and high pressure Introduction Extensive research has been conducted on the structures and physical properties of the semimetal element bismuth (Bi) due to its special status between metals and nonmetals [1-5]. The common structure of Bi under ambient conditions is the so-called rhombohedral A7 structure, which can be considered a distortion of the simple cubic structure and is stabilized by the Peierls-Jones mechanism [1, 6]. The shortest metallic bonds in the Bi structure have some covalency, resulting in a layer-like network, compared with the weak bonding observed between layers. Therefore, the unique bonding environment of Bi results in rich physical behaviors such as solid or liquid transitions at various pressures [7-11], unique melting properties [5, 11, 12-14], and quantum transport [15-18]. Recent research has studied some special forms of Bi such as Bi nanowires [19], Bi nanotubes [20], Bi clusters [21-23], and polycrystalline Bi bulk with distorted A7 structures [24]. As is well known, the mirostructure of matter determines its macrophysical properties. For example, Bi with a common A7 structure is classified as a semimetal with a small band overlap, while Bi nanostructures become semiconductors with a small direct band gap due to the quantum size effect [20]. In this paper, in situ differential
scanning calorimetry (DSC) and transmission electron microscopy (TEM) measurements are used to study the unique melting behavior of polycrystalline Bi samples quenched upon HTHP treatment. We show that a variety of derivative polytypes with distorted A7 structures exist in these samples. These show an extremely interesting large magnetoresistance effect at ambient pressure [25]. Material and methods Bi granules (Alfa Aesar, 99.999%) were sintered and formed into polycrystalline Bi cylinders using an HTHP method similar to that reported in [24]. For simplicity, the quenched Bi samples after the HTHP treatment are denoted as Bi-T-P, where T and P represent the quench temperature and the applied pressure, respectively. A Perkin-Elmer differential scanning calorimeter (DSC 8000) was used to monitor physical or chemical reactions, including phase transitions (such as solid-solid or solid-liquid), crystal-glass transitions, decomposition, and combination. The Bi samples were shaped to form small cuboids with a mass of 30-35 mg. These were placed in an aluminum pan and treated under defined temperature programs of various thermal scan rates and heating cycles under an inert argon atmosphere. The obtained DSC curves were calibrated by eliminating the background effect of the empty aluminum pan, which was exclusively tested. Both the raw granules and the quenched bulk samples were ground in an agate mortar. Then, the fine pieces were loaded into a copper microgrid for selected area electron diffraction (SAED). TEM measurements were carried out on a JEM-2100 with an accelerating voltage of 200 kV. During the measurements, a similar electron beam with low intensity was used by narrowing the diaphragm to block 80~90% of the electron beam. Results and discussions Figure 1a shows the DSC curves of the HTHP-treated samples and the raw Bi material during the first heating cycle with a heating rate of 10 ℃/min. For the raw Bi, a decalescence peak is noted at a temperature T1 of 275℃, which is a little higher than the reference melting point of 271.3℃ for the common Bi crystal [7]. This represents a normal melting peak. However, for the samples quenched at a pressure of 2 GPa and temperatures above 2000℃, a second decalescence peak appears at the temperature T2, which is lower than the normal melting T1 for common Bi. At measurement temperatures up to 300℃, these samples slowly cooled at a rate of 10 ℃ /min to room temperature. After the first heating cycle, the second heating cycle begins with the same heating rate and test temperatures. The shoulder peak is observed again and becomes more significant for the HTHP-treated samples during the second heating cycle (Fig. 1b). In comparison, the decalescence peak of the raw Bi is still the same as the common melting signal. The appearance of the additional decalescence peak during the heating cycles indicates that a distinct thermodynamic process occurs in the HTHP-quenched Bi. The morphologies of the HTHP-treated Bi samples after the heating cycles show large differences compared to the morphologies of the raw Bi. As shown in Fig. 1b inset, the raw Bi changes its bulk shape from an original irregularity to a neat ball, indicating that it normally melted during the
heating cycles. However, the HTHP-treated Bi samples retain their initial rectangular morphology even after 12 heating cycles. The existence of some original pits and scratches indicate that the samples did not melt completely.
Figure 1 DSC heating curves measured at 10 ℃/min for raw Bi and HTHP treated Bi samples for (a) the first heating cycle up to 300℃ and (b) the second heating cycles up to 300℃ after cool down of the first cycle. Inset: the morphology photos of raw Bi, and HTHP-treated Bi samples.
Multiple heating cycles at a rate of 10 ℃/min at temperatures up to 300℃ were conducted in order to observe the changes in the double decalescence peaks of the Bi-2000-2 sample previously treated at 2 GPa and 2000℃. As shown in figure 2a, in the initial three cycles, the relative peak intensity and positions of T1 and T2 shift irregularly. When the heating cycles are executed more than four times, the DSC curves of the sample became similar. The additional peak is located on the left of the main peak, and the difference ΔT= T1−T2 is constant at 3.8℃for the last nine heating cycles. To further consider the effect of the heating rate on the decalescence peaks, the different heating rates of 0.5, 2.5, 10, and 40 ℃/min have been tested for the same Bi-2000-2 sample after 12 heating cycles (Fig. 2b). With a decrease in the heating rate, the positions of the double peaks shift towards lower temperatures, and the peak at T2 becomes sharper and more independent at 0.5 ℃/min, indicating that a distinct thermal behavior occurs at this temperature.
Figure 2 (a) DSC heating curves with multiple heating cycles at a rate of 10 ℃/min at temperatures up to 300℃ for the Bi-2000-2 sample. (b) DSC heating curves at 40 ℃/min, 10 ℃/min, 2.5 ℃/min, and 0.5 ℃/min for the Bi-2000-2 sample after the first 12 heating cycles.
The TEM measurement during the in situ heating process is helpful to directly observe the melting behavior of Bi. For the common raw Bi under electron beam irradiation, the sample shape changes from the undisturbed state to the final spherical shape due to melting, as measured in situ at temperatures of 100, 200, and 220℃ (Fig. 3a-c). In particular, under electron irradiation at a temperature of 220℃, it was observed that the sample melted and partially formed several small liquid nanospheres. Conversely, the HTHP-treated Bi sample could sustain its basic morphology (Fig. 3d-f). When the sample flake was heated to 300℃ and then cooled to 220℃ (Fig. 3f), it was observed that the grain boundaries of the sample became almost invisible compared with those at the initial heating temperatures of 100 and 200℃ (Fig. 3d and e). This indicates that although the heating temperature exceeded the common melting point of Bi, the flake is intact and only the grains are recrystallized. The reason for this result may be the incomplete melting of the HTHP-treated Bi. This is similar to the macroscopic morphology observation after the DSC measurement (Fig. 1f and g). Although the grain boundary changes, the analysis of the SAED data shows that the flake is still crystalline Bi (Fig. 3d-e inset).
Figure 3 In situ TEM measurements for raw Bi and Bi-2000-2. (a), (b), (c) TEM images collected at 100℃, 200℃ and 220℃, respectively, for a broken piece of the raw Bi. (d), (e) TEM images at 100℃ and 200℃, respectively, for a broken piece of Bi-2000-2. Insets are the collected SAEDs along the zone axis of [110]. (f) TEM image and SAED along the zone axis of [2-21] (Inset) after the increase in temperature to 300℃ and then a temperature reduction to 220℃.
From the above observations, the anomalous melting behavior of the HTHP-treated Bi has two important aspects. The first aspect is the appearance of the additional endothermic T2 peak before the normal melting T1 peak. The other aspect is the ability of the HTHP-treated Bi to maintain initial morphologies at temperatures beyond the common melting point. Considering the coexistence of multiple distorted polytypes with normal A7-Bi in the HTHP-treated samples [24], there is a possible explanation. Namely, the first endothermic process before normal melting may be due to the relaxation of some metastable polytypes. The balance of the double endothermic peaks after several heating cycles also implies the relaxation counterpoise of the metastable polytypes. The melting of the A7 configuration dispersed in the multiple-phase samples causes the second endothermic peak. The ability to maintain morphologies may originate from the enhanced covalence of the distorted polytypes. Conclusions To summarize, we studied the anomalous melting behavior of the HTHP-treated polycrystalline bismuth using DSC and TEM measurements. An additional endothermic peak appears before the melting peak of the normal A7-Bi. The polycrystalline samples have the ability to maintain their morphology during multiple heating cycles and temperatures beyond the normal melting point. This research may provide an approach to study the structures and other properties of the HTHP-treated group V semimetal elements due to their similar A7 structures under ambient conditions.
Acknowledgments This work was supported by the National Natural Science Foundation of China (51172197, 51121061, 51332005, 11025418 and 91022029) and the Ministry of Science and Technology of China (2011CB808205 and 2010CB731605).
References [1] P. Cucka, and C.S.Barrett, Acta Cryst., 15 (1962), 865. [2] K.J. Chang and Marvin L. Cohen, Phys. Rev. B, 33 (1986), 7371. [3] Richard J. Needs, Phys. Rev. B, 33 (1986), 3778. [4] J-P. Issi, Aust. J. Phys., 32 (1979), 585. [5] J.P. Gaspard, R. Bellissent, A. Menelle, C.Bergman, and R.Ceolin, Il . Nuovo. Cimento., 12 (1990), 649. [6] Ph. Hofmann, Prog. Surf. Sci., 81 (2006), 191. [7] E. Yu Tonkov, E.G. Ponyatovsky, Phase Transformations of Elements Under High Pressure. CRC press, 2004. [8] F.P. Bundy, Phys. Rev., 110 (1958), 314. [9] A.G. Umnov, V.V. Brazhkin, S.V. Popova, and R.N. Voloshin, J.Phys.: Condens. Matter, 4 (1992), 1427. [10] R.F. Smith, J.H. Eggert, M.D. Saculla, A.F. Jankowski, M. Bastea, and D.G. Hicks, et al., Phys. Rev. Lett., 101 (2008) 065701. [11] Y. Greenberg, E. Yahel, E.N. Caspi, C. Benmore, B. Beuneu, and M.P. Dariel, et al., EPL, 86 (2009), 36004. [12] Nathan Argaman, Phys. Lett. A, 374 (2010) 3982. [13] M.G. Gorman, R. Briggs, E.E. Mcbride, A. Higginbotham, B. Arnold, and J.H Eggert, et al., Phys. Rev. Lett., 155 (2015) 095701. [14] J. Bai, J. Yu, and T. wang, Word Journal of Mechanices, 4 (2014), 203. [15] F.Y. Yang, K. Liu, K. Hong, D.H. Reich, P.C. Searson, and C.L. Chien. Science, 284 (1999), 1335. [16] K. Behnia, L. Balicas, and Y. Koelevich, Science, 317 (2007), 1729. [17] R. Kuchler, L. Steinke, R. Daou, M. Brando, K. Behnia, and F. Steglich, Nat. Mater., 13 (2014), 461. [18] L. Li, J.G. Checkelsky, Y.S. Hor, C. Uher, A.F. Hebard, and R.J. Cava, Science, 321 (2008), 547. [19] Z. Zhang, D. Gekhtman, M. S. Dresselhaus, and J. Y. Ying, Chem Mater 11 (1999), 1659-1665. [20] G. Zhou, L. Li, and G. H. Li, J. Appl. Phys., 109 (2011), 114311. [21] S. Yin, X. Xu, R. Moro, and Walt A. de Heer. Phys. Rev. B, 72 (2005) 174410. [22] L. Gao, P. Li, H. Lu, S.F. Li, and Z.X. Guo. J. Chem. Phys. 128 (2008) 194304. [23] J. Akola, N. Atodiresei, J. Kalikka, J. Larrucea, and R.O. Jones, J. Chem. Phys. 141 (2014), 194503. [24] Y. Shu, W. Hu, Z. Liu, G. Shen, B. Xu, and Z. Zhao, et al., http://arxiv.org/abs/1508.05179 . [25] Yu Shu, et al., Physica Status Solidi B, pssb.201552578R1. (Revisions Being Processed).
Highlights An additional endothermic peak had been observed in the DSC curves of high temperature and high pressure quenched bulk Bi samples and the initial morphology characteristics of these samples is retained during repeated heating cycles.
PII: DOI: Reference:
S0167-577X(15)31018-1 http://dx.doi.org/10.1016/j.matlet.2015.12.065 MLBLUE20025
To appear in: Materials Letters Received date: 13 November 2015 Accepted date: 14 December 2015 Cite this article as: Yu Shu, Wentao Hu, Zhisheng Zhao, Limin Wang, Zhongyuan Liu, Yongjun Tian and Dongli Yu, Anomalous melting behavior of polycrystalline bismuth quenched at high temperature and high pressure, Materials Letters, http://dx.doi.org/10.1016/j.matlet.2015.12.065 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Anomalous melting behavior of polycrystalline bismuth quenched at high temperature and high pressure Yu Shu, Wentao Hu, Zhisheng Zhao, Limin Wang, Zhongyuan Liu, Yongjun Tian, and Dongli Yu* State Key Lab of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China
Abstract Under ambient conditions, bismuth (Bi) adopts a rhombohedral A7 structure, yet Bi treated at high temperature and high pressure (HTHP) has been proven to have derivative structural polytypes that coexist with the common A7 structure. This paper studies the melting behavior of HTHP-treated polycrystalline Bi using differential scanning calorimetry (DSC) and in situ transmission electron microscopy (TEM) measurements. The Bi samples quenched at a pressure of 2 GPa and a temperature above 2000℃ show an additional endothermic peak before the common melting peak of A7-Bi in the DSC curves. This is probably due to the high-temperature relaxation of the distorted A7 configuration. The samples maintain their initial morphology characteristics during repeated heating cycles, indicating the incomplete melting of distorted Bi polytypes. Keyword: Bismuth, thermal properties, electron microscopy, deformation, high temperature and high pressure Introduction Extensive research has been conducted on the structures and physical properties of the semimetal element bismuth (Bi) due to its special status between metals and nonmetals [1-5]. The common structure of Bi under ambient conditions is the so-called rhombohedral A7 structure, which can be considered a distortion of the simple cubic structure and is stabilized by the Peierls-Jones mechanism [1, 6]. The shortest metallic bonds in the Bi structure have some covalency, resulting in a layer-like network, compared with the weak bonding observed between layers. Therefore, the unique bonding environment of Bi results in rich physical behaviors such as solid or liquid transitions at various pressures [7-11], unique melting properties [5, 11, 12-14], and quantum transport [15-18]. Recent research has studied some special forms of Bi such as Bi nanowires [19], Bi nanotubes [20], Bi clusters [21-23], and polycrystalline Bi bulk with distorted A7 structures [24]. As is well known, the mirostructure of matter determines its macrophysical properties. For example, Bi with a common A7 structure is classified as a semimetal with a small band overlap, while Bi nanostructures become semiconductors with a small direct band gap due to the quantum size effect [20]. In this paper, in situ differential
scanning calorimetry (DSC) and transmission electron microscopy (TEM) measurements are used to study the unique melting behavior of polycrystalline Bi samples quenched upon HTHP treatment. We show that a variety of derivative polytypes with distorted A7 structures exist in these samples. These show an extremely interesting large magnetoresistance effect at ambient pressure [25]. Material and methods Bi granules (Alfa Aesar, 99.999%) were sintered and formed into polycrystalline Bi cylinders using an HTHP method similar to that reported in [24]. For simplicity, the quenched Bi samples after the HTHP treatment are denoted as Bi-T-P, where T and P represent the quench temperature and the applied pressure, respectively. A Perkin-Elmer differential scanning calorimeter (DSC 8000) was used to monitor physical or chemical reactions, including phase transitions (such as solid-solid or solid-liquid), crystal-glass transitions, decomposition, and combination. The Bi samples were shaped to form small cuboids with a mass of 30-35 mg. These were placed in an aluminum pan and treated under defined temperature programs of various thermal scan rates and heating cycles under an inert argon atmosphere. The obtained DSC curves were calibrated by eliminating the background effect of the empty aluminum pan, which was exclusively tested. Both the raw granules and the quenched bulk samples were ground in an agate mortar. Then, the fine pieces were loaded into a copper microgrid for selected area electron diffraction (SAED). TEM measurements were carried out on a JEM-2100 with an accelerating voltage of 200 kV. During the measurements, a similar electron beam with low intensity was used by narrowing the diaphragm to block 80~90% of the electron beam. Results and discussions Figure 1a shows the DSC curves of the HTHP-treated samples and the raw Bi material during the first heating cycle with a heating rate of 10 ℃/min. For the raw Bi, a decalescence peak is noted at a temperature T1 of 275℃, which is a little higher than the reference melting point of 271.3℃ for the common Bi crystal [7]. This represents a normal melting peak. However, for the samples quenched at a pressure of 2 GPa and temperatures above 2000℃, a second decalescence peak appears at the temperature T2, which is lower than the normal melting T1 for common Bi. At measurement temperatures up to 300℃, these samples slowly cooled at a rate of 10 ℃ /min to room temperature. After the first heating cycle, the second heating cycle begins with the same heating rate and test temperatures. The shoulder peak is observed again and becomes more significant for the HTHP-treated samples during the second heating cycle (Fig. 1b). In comparison, the decalescence peak of the raw Bi is still the same as the common melting signal. The appearance of the additional decalescence peak during the heating cycles indicates that a distinct thermodynamic process occurs in the HTHP-quenched Bi. The morphologies of the HTHP-treated Bi samples after the heating cycles show large differences compared to the morphologies of the raw Bi. As shown in Fig. 1b inset, the raw Bi changes its bulk shape from an original irregularity to a neat ball, indicating that it normally melted during the
heating cycles. However, the HTHP-treated Bi samples retain their initial rectangular morphology even after 12 heating cycles. The existence of some original pits and scratches indicate that the samples did not melt completely.
Figure 1 DSC heating curves measured at 10 ℃/min for raw Bi and HTHP treated Bi samples for (a) the first heating cycle up to 300℃ and (b) the second heating cycles up to 300℃ after cool down of the first cycle. Inset: the morphology photos of raw Bi, and HTHP-treated Bi samples.
Multiple heating cycles at a rate of 10 ℃/min at temperatures up to 300℃ were conducted in order to observe the changes in the double decalescence peaks of the Bi-2000-2 sample previously treated at 2 GPa and 2000℃. As shown in figure 2a, in the initial three cycles, the relative peak intensity and positions of T1 and T2 shift irregularly. When the heating cycles are executed more than four times, the DSC curves of the sample became similar. The additional peak is located on the left of the main peak, and the difference ΔT= T1−T2 is constant at 3.8℃for the last nine heating cycles. To further consider the effect of the heating rate on the decalescence peaks, the different heating rates of 0.5, 2.5, 10, and 40 ℃/min have been tested for the same Bi-2000-2 sample after 12 heating cycles (Fig. 2b). With a decrease in the heating rate, the positions of the double peaks shift towards lower temperatures, and the peak at T2 becomes sharper and more independent at 0.5 ℃/min, indicating that a distinct thermal behavior occurs at this temperature.
Figure 2 (a) DSC heating curves with multiple heating cycles at a rate of 10 ℃/min at temperatures up to 300℃ for the Bi-2000-2 sample. (b) DSC heating curves at 40 ℃/min, 10 ℃/min, 2.5 ℃/min, and 0.5 ℃/min for the Bi-2000-2 sample after the first 12 heating cycles.
The TEM measurement during the in situ heating process is helpful to directly observe the melting behavior of Bi. For the common raw Bi under electron beam irradiation, the sample shape changes from the undisturbed state to the final spherical shape due to melting, as measured in situ at temperatures of 100, 200, and 220℃ (Fig. 3a-c). In particular, under electron irradiation at a temperature of 220℃, it was observed that the sample melted and partially formed several small liquid nanospheres. Conversely, the HTHP-treated Bi sample could sustain its basic morphology (Fig. 3d-f). When the sample flake was heated to 300℃ and then cooled to 220℃ (Fig. 3f), it was observed that the grain boundaries of the sample became almost invisible compared with those at the initial heating temperatures of 100 and 200℃ (Fig. 3d and e). This indicates that although the heating temperature exceeded the common melting point of Bi, the flake is intact and only the grains are recrystallized. The reason for this result may be the incomplete melting of the HTHP-treated Bi. This is similar to the macroscopic morphology observation after the DSC measurement (Fig. 1f and g). Although the grain boundary changes, the analysis of the SAED data shows that the flake is still crystalline Bi (Fig. 3d-e inset).
Figure 3 In situ TEM measurements for raw Bi and Bi-2000-2. (a), (b), (c) TEM images collected at 100℃, 200℃ and 220℃, respectively, for a broken piece of the raw Bi. (d), (e) TEM images at 100℃ and 200℃, respectively, for a broken piece of Bi-2000-2. Insets are the collected SAEDs along the zone axis of [110]. (f) TEM image and SAED along the zone axis of [2-21] (Inset) after the increase in temperature to 300℃ and then a temperature reduction to 220℃.
From the above observations, the anomalous melting behavior of the HTHP-treated Bi has two important aspects. The first aspect is the appearance of the additional endothermic T2 peak before the normal melting T1 peak. The other aspect is the ability of the HTHP-treated Bi to maintain initial morphologies at temperatures beyond the common melting point. Considering the coexistence of multiple distorted polytypes with normal A7-Bi in the HTHP-treated samples [24], there is a possible explanation. Namely, the first endothermic process before normal melting may be due to the relaxation of some metastable polytypes. The balance of the double endothermic peaks after several heating cycles also implies the relaxation counterpoise of the metastable polytypes. The melting of the A7 configuration dispersed in the multiple-phase samples causes the second endothermic peak. The ability to maintain morphologies may originate from the enhanced covalence of the distorted polytypes. Conclusions To summarize, we studied the anomalous melting behavior of the HTHP-treated polycrystalline bismuth using DSC and TEM measurements. An additional endothermic peak appears before the melting peak of the normal A7-Bi. The polycrystalline samples have the ability to maintain their morphology during multiple heating cycles and temperatures beyond the normal melting point. This research may provide an approach to study the structures and other properties of the HTHP-treated group V semimetal elements due to their similar A7 structures under ambient conditions.
Acknowledgments This work was supported by the National Natural Science Foundation of China (51172197, 51121061, 51332005, 11025418 and 91022029) and the Ministry of Science and Technology of China (2011CB808205 and 2010CB731605).
References [1] P. Cucka, and C.S.Barrett, Acta Cryst., 15 (1962), 865. [2] K.J. Chang and Marvin L. Cohen, Phys. Rev. B, 33 (1986), 7371. [3] Richard J. Needs, Phys. Rev. B, 33 (1986), 3778. [4] J-P. Issi, Aust. J. Phys., 32 (1979), 585. [5] J.P. Gaspard, R. Bellissent, A. Menelle, C.Bergman, and R.Ceolin, Il . Nuovo. Cimento., 12 (1990), 649. [6] Ph. Hofmann, Prog. Surf. Sci., 81 (2006), 191. [7] E. Yu Tonkov, E.G. Ponyatovsky, Phase Transformations of Elements Under High Pressure. CRC press, 2004. [8] F.P. Bundy, Phys. Rev., 110 (1958), 314. [9] A.G. Umnov, V.V. Brazhkin, S.V. Popova, and R.N. Voloshin, J.Phys.: Condens. Matter, 4 (1992), 1427. [10] R.F. Smith, J.H. Eggert, M.D. Saculla, A.F. Jankowski, M. Bastea, and D.G. Hicks, et al., Phys. Rev. Lett., 101 (2008) 065701. [11] Y. Greenberg, E. Yahel, E.N. Caspi, C. Benmore, B. Beuneu, and M.P. Dariel, et al., EPL, 86 (2009), 36004. [12] Nathan Argaman, Phys. Lett. A, 374 (2010) 3982. [13] M.G. Gorman, R. Briggs, E.E. Mcbride, A. Higginbotham, B. Arnold, and J.H Eggert, et al., Phys. Rev. Lett., 155 (2015) 095701. [14] J. Bai, J. Yu, and T. wang, Word Journal of Mechanices, 4 (2014), 203. [15] F.Y. Yang, K. Liu, K. Hong, D.H. Reich, P.C. Searson, and C.L. Chien. Science, 284 (1999), 1335. [16] K. Behnia, L. Balicas, and Y. Koelevich, Science, 317 (2007), 1729. [17] R. Kuchler, L. Steinke, R. Daou, M. Brando, K. Behnia, and F. Steglich, Nat. Mater., 13 (2014), 461. [18] L. Li, J.G. Checkelsky, Y.S. Hor, C. Uher, A.F. Hebard, and R.J. Cava, Science, 321 (2008), 547. [19] Z. Zhang, D. Gekhtman, M. S. Dresselhaus, and J. Y. Ying, Chem Mater 11 (1999), 1659-1665. [20] G. Zhou, L. Li, and G. H. Li, J. Appl. Phys., 109 (2011), 114311. [21] S. Yin, X. Xu, R. Moro, and Walt A. de Heer. Phys. Rev. B, 72 (2005) 174410. [22] L. Gao, P. Li, H. Lu, S.F. Li, and Z.X. Guo. J. Chem. Phys. 128 (2008) 194304. [23] J. Akola, N. Atodiresei, J. Kalikka, J. Larrucea, and R.O. Jones, J. Chem. Phys. 141 (2014), 194503. [24] Y. Shu, W. Hu, Z. Liu, G. Shen, B. Xu, and Z. Zhao, et al., http://arxiv.org/abs/1508.05179 . [25] Yu Shu, et al., Physica Status Solidi B, pssb.201552578R1. (Revisions Being Processed).
Highlights An additional endothermic peak had been observed in the DSC curves of high temperature and high pressure quenched bulk Bi samples and the initial morphology characteristics of these samples is retained during repeated heating cycles.