Superconductivity in mercurides of strontium

A large variety of chemical and physical properties are exhibited by mercurides and amalgams. In this work, we have successfully examined seven strontium mercurides: SrHg₁₁, SrHg₈, Sr₁₀Hg₅₅, SrHg₂, SrHg, Sr₃Hg₂, and Sr₃Hg. The interest in the mercury-rich region is motivated by the large number of mercury-based superconductors that have high mercury content. At the same time, the preparation on the mercury-rich side of the binary phase diagram is experimentally non-trivial, due to the high vapor pressure of mercury and extreme air-sensitivity of mercury-rich compounds. By employing a set of specialized techniques, we were able to discover superconductivity in three mercury-strontium compounds – SrHg₁₁ ($T_c=3.2\pm 0.3$ K, $H_{c2}=0.18\pm 0.05$ T), SrHg₈ ($T_c=3.0\pm 0.1$ K, $H_{c2}=0.35\pm 0.02$ T), and Sr₁₀Hg₅₅ ($T_c=2.2\pm 0.25$ K, $H_{c2}=0.54\pm 0.05$ T).

1 Introduction

Mercury-based compounds (mercurides) and mercury-based alloys (amalgams) have long been of significant interest in chemistry and physics (Ferro, 1954; Bruzzone and Merlo, 1973; Bruzzone and Merlo, 1974; Bruzzone and Merlo, 1975). From their everyday applications (Bjørklund, 1989; Sappl et al., 2017) to their unique superconducting and topological states (Pelloquin et al., 1993; König et al., 2007), a plethora of exciting phenomena emerge in these systems. Many mercury-based materials have unique and complex crystal structures (Tkachuk and Mar, 2008), and it is suggested that the complexity of these structures is directly related to their intriguing physical properties (Steurer and Dshemuchadse, 2016; Dubois and Belin-Ferré, 2010; Urban and Feuerbacher, 2004; Conrad et al., 2009; Samson, 1962; Weber et al., 2009; Svanidze et al., 2019; Prots et al., 2022b). Among the alkali- and alkali-earth-based mercurides, a large variety of crystallographic motifs was observed with almost 40 structure types present, ranging in complexity from simple CsCl structure type (2 atoms per unit cell, Pearson symbol $\bar{c}P2$) to the exceptionally complex Sm₁₁Cd₄₅ structure type (448 atoms per unit cell, Pearson symbol $cF448$). Despite these fascinating atomic environments and peculiar physical properties, an overwhelming majority of mercury-based systems have not been studied in detail – likely due to the difficulties associated with such work (Bjørklund et al., 2017; Hoch, 2019). Moreover, their extreme air- and moisture-sensitivity (Witthaut et al., 2023; Prots et al., 2022a; Prots et al., 2022b), call for a specialized preparation methodology.

The first analysis of mercury-strontium compounds and amalgams was carried out in the end of 19th century (Kerp, 1898; Kerp et al., 1900; Guntz and Roederer, 1906; Devoto and Recchia, 1930), with the first study of crystal structure dating back to 1954 (Ferro, 1954). The binary phase diagram was first unified 20 years later (Bruzzone and Merlo, 1974), and re-evaluated in 2005 (Gumiński, 2005), resulting in reformulation of multiple phases (Kerp et al., 1900; Guntz and Roederer, 1906; Devoto and Recchia, 1930). Both mercurides as well as isostructural families of compounds have been studied after that: for example, Sr₃Hg₂ (Druska et al., 1996), $A$Hg₁₁ ($A$ = K, Rb, Ba or Sr) (Biehl and Deiseroth, 1999), SrHg₃ (Wendorff and Röhr, 2018), and $A_{11-x}$Hg_54+x ($A$ = Ca or Sr) (Tkachuk and Mar, 2008). The aforementioned work on the mercury-strontium compounds has so far focused on the chemical features of these compounds (Ferro, 1954; Kerp et al., 1900; Guntz and Roederer, 1906; Devoto and Recchia, 1930; Biehl and Deiseroth, 1999; Wendorff and Röhr, 2018), leaving the physical properties unknown. Our previous work on mercurides revealed a number of new superconducting (Prots et al., 2022a; Witthaut et al., 2023) and magnetic (Svanidze et al., 2019; Prots et al., 2022b) compounds, which motivated us to re-assess the mercury-strontium binary system. In the current work, we have successfully synthesized SrHg₁₁, SrHg₈, Sr₁₀Hg₅₅, SrHg₂, SrHg, Sr₃Hg₂, and Sr₃Hg. The mercury-rich compounds SrHg₁₁, SrHg₈, and Sr₁₀Hg₅₅ were synthesized in single-crystalline form. Despite their exceptional air-sensitivity, it was possible to conclusively establish that these compounds exhibit superconductivity with critical temperatures Sr₁₀Hg₅₅ ($T_c=2.2\pm 0.25$ K), SrHg₈ ($T_c=3.0\pm 0.1$ K), and SrHg₁₁ ($T_c=3.2\pm 0.3$ K), respectively. The other mercury-strontium phases are para- or diamagnetic down to $T=1.8$ K. This work expands the number of currently known superconducting alkali- or alkali-earth-based mercurides, as summarized in Figure 1 (Claeson and Luo, 1966; Roberts, 1976; Biehl and Deiseroth, 1999; Claeson and Luo, 1966; Hohl et al., 2023; Hänisch et al., 2023).

Figure 1

Figure 1. Binary superconductors containing mercury and alkali or alkali-earth elements. Superconductors reported as part of this work are marked with blue squares, while those reported previously are shown as red circles (Claeson and Luo, 1966; Roberts, 1976; Biehl and Deiseroth, 1999; Claeson and Luo, 1966; Hohl et al., 2023; Hänisch et al., 2023). The maximum value for the superconducting temperature $T_c$ appears to be slightly below that of pure Hg ($T_c$ = 4.2 K).

2 Materials and methods

Several issues complicate experimental investigations of mercury-containing materials – toxicity, high vapor pressure, high chemical reactivity, and extreme air sensitivity – call for a specialized laboratory environment. As we have previously shown (Witthaut et al., 2023; Prots et al., 2022a; Prots et al., 2022b; Svanidze et al., 2019), it is possible to conclusively establish chemical and physical properties of mercurides and amalgams by utilizing a set of dedicated experimental techniques (Leithe-Jasper et al., 2006).

All of the samples were synthesized by combining Hg (droplet, Alfa Aesar, 99.999%) and Sr (pieces, Alfa Aesar, 99.95%), with the Sr:Hg ratio varied from 2:98 to 79:21 (Table 1). Elements were sealed in tantalum tubes, in order to preserve stoichiometry. To protect samples from air and moisture, all syntheses were performed in an argon filled glove box system. The tubes were heated up to 500°C over 24 h and held there for a further 50 h before cooling back to room temperature over 96 h, with the slow cooling ensuring that the samples were able to crystallize efficiently. Mercury-rich samples were then placed into specialized crucibles (Canfield and Svanidze, 2024) (Figure 2) and centrifuged at room temperature to remove excess mercury. While most of the mercury can be eliminated this way, the small remainder can usually be removed by allowing the crystals to sit on gold foil for several days. Resultant single crystals of SrHg₁₁, SrHg₈, and Sr₁₀Hg₅₅ are shown in Figure 2 (bottom). The rest of the compounds were synthesized in polycrystalline form. It is important to note, that secondary phases were present in all samples (Table 1).

Table 1

Table 1. Summary of phase analysis in mercury-strontium samples, synthesized as part of this work.

Figure 2

Figure 2. Top: Experimental solutions used for synthesis and characterization of mercury-strontium compounds. Left: arc melter used for sealing tantalum tubes under argon. Center, top: sealed tantalum tube. Center bottom: Canfield-Svanidze crucible set used for centrifugation of samples. Right, top: tantalum ampoule used for DTA measurements. Right, bottom: modified stainless steel high-pressure capsule used for DSC as an alternative to DTA on mercury-rich samples. Bottom: Single crystals of superconducting strontium mercurides–SrHg₁₁ (sample 1), SrHg₈ (sample 4), and Sr₁₀Hg₅₅ (sample 4, Table 1).

Powder X-ray diffraction was performed on a Huber G670 Image plate Guinier camera with a Ge-monochromator (Cu$K{\alpha }_1$, $\lambda$ = 1.54056 Å). Powders were sealed between two Kapton films to prevent decomposition. Phase identification was carried out using WinXPow software (Darmstadt STOE and Cie GmbH, 2019). The lattice parameters were determined by a least-squares refinement using the peak positions, extracted by profile fitting. The WinCSD software (Akselrud and Grin, 2014) was used for crystallographic analysis. Single crystal diffraction was not carried out due to the extreme air-sensitivity of these materials. The values of the lattice parameters, refined from powder X-ray data, were in agreement with those reported previously (Table 2).

Table 2

Table 2. Properties of mercury-strontium phases, examined as part of this work.

Differential thermal analysis (DTA) was performed using STA 449 F3 Jupiter (NETZSCH) and DCS 404 Pegasus (NETZSCH) set-ups with a 10 K/min heating and cooling rate. The samples were measured in the temperature range from 25°C to 875°C, with the exact ranges based on expected transitions. The previously published mercury-strontium binary phase diagram defined by (Gumiński, 2005) was used as a guide. Samples were sealed in tantalum ampoules, under argon. The particularly challenging part was to evaluate the mercury-rich samples, given their high vapor pressure – this region of the binary phase diagram is also the least explored one. For this, modified stainless steel high-pressure capsules with a volume of 30 $\mu$L from PerkinElmer were used (Figure 2). The sample masses were around 40–50 mg for DTA and 90–100 mg for DSC.

Magnetic properties were examined using a Quantum Design (QD) Magnetic Property Measurement System in the temperature range of 1.8–300 K and under various applied magnetic fields. Samples were sealed in glass tubes to prevent reaction with air. The specific heat data were collected on a QD Physical Property Measurement System from 0.4 K to 10 K and under various applied magnetic fields. Given the high air-sensitivity of the mercury-rich phases, samples were covered with Apiezon N vacuum grease, which resulted in a rather large background (Figure 3, panel a) – and while the transition to the superconducting state was observed, it was unfortunately not possible to carry out an in-depth analysis of the superconducting state. The corresponding $H_{c2}-T$ phase diagrams were constructed and fit to Ginzburg–Landau relation $H_{c2}(T)=H_{c2}(0)(1-{(T/T_c)}^2)/(1+{(T/T_c)}^2)$ describing the temperature dependence of the upper critical field $H_{c2}$. Given low critical temperatures, it was not possible to extract the values of lower critical field $H_{c1}$. The critical temperatures were extracted from the magnetic susceptibility and specific heat data by taking the mid-point of the superconducting transition. For SrHg₈ and SrHg₁₁, a significant variation of the $T_c$ values can be explained by the presence of a homogeneity range (Table 2; Figure 3).

Figure 3

Figure 3. Superconducting properties of strontium mercurides Sr₁₀Hg₅₅, SrHg₈, and SrHg₁₁. (A) Specific heat for Sr₁₀Hg₅₅ (B–D) Magnetic susceptibility for the three superconducting samples, each panel shows one sample which has multiple superconducting transitions. Both ZFC (zero-field-cooled) and FC (field-cooled) curves are shown. (E–G) $H-T$ phase diagrams constructed from the heat capacity and magnetic measurements, from which the values of $T_c$ and $H_{c2}$ can be extracted. For SrHg₈ and SrHg₁₁, variation in stoichiometry from sample to sample yields slightly different $T_c$ values.

3 Results and discussion

As mentioned above, the goal of this work was to revisit the mercury-strontium phases and explore their physical properties. In order to clarify the phases and their evolution with temperature, a complementary analysis of the powder X-ray diffraction and differential thermal analysis was implemented. The following phases were examined: SrHg₁₁, SrHg₈, Sr₁₀Hg₅₅, SrHg₂, SrHg, Sr₃Hg₂, and Sr₃Hg. No evidence of SrHg₃ (Wendorff and Röhr, 2018) or Sr₂Hg (Bruzzone and Merlo, 1974; Gumiński, 2005) was found. The difficulty in stabilizing the former can perhaps be explained by a relatively short liquidus line (Wendorff and Röhr, 2018).

Motivated by the lack of publications addressing physical properties of strontium mercurides, we have performed a thorough analysis of these materials. Much like in our previous work (Witthaut et al., 2023; Prots et al., 2022a; Prots et al., 2022b; Svanidze et al., 2019), we have taken considerable care to protect our samples from decomposition in order to study their intrinsic properties. All of the phases from 25 at.% strontium and up, were found to be either dia- or paramagnetic down to the lowest measured temperature $T=1.8$ K (not shown). However, for the mercury-rich samples, three new superconducting phases were identified – SrHg₁₁, SrHg₈, and Sr₁₀Hg₅₅. While all of these phases were grown in single crystal form, they contain some inclusions of secondary phases (Table 1). This explains why magnetization measurements, shown in Figure 3, show multiple transitions. Each of these transitions can be assigned to the respective phases, present in these samples – SrHg₁₁ ($T_c=3.2\pm 0.3$ K), SrHg₈ ($T_c=3.0\pm 0.1$ K), or Sr₁₀Hg₅₅ ($T_c=2.2\pm 0.25$ K). Uncertainties in $T_c$ were determined by averaging the values obtained from various measurements and various samples. The majority and minority phases in each sample were identified $via$ powder diffraction analysis. For the heat capacity data, a single anomaly is seen around $T=2.2$ K, corresponding to the superconducting transition of Sr₁₀Hg₅₅. This transition is driven to lower temperatures as magnetic field is increased, in accordance with what is expected for a superconductor. Based on the joint analysis of magnetic susceptibility and specific heat data, the $H-T$ phase diagrams were constructed for SrHg₁₁, SrHg₈, and Sr₁₀Hg₅₅. By fitting the data to the Ginzburg–Landau relation, as shown in Figure 3 (bottom), values of the respective $T_c(0)$ and $H_{c2}(0)$ were extracted, as summarized in Table 2. For SrHg₈ and SrHg₁₁, there appears to exist a range of values for both $T_c$ and $H_{c2}$. This can likely be attributed to a presence of the homogeneity range of these materials, as deduced by slight variation of the lattice parameters, summarized in Table 2. The presence of a homogeneity range in the Sr_11-xHg_54+x compound was previously reported to arise from disorder resulting from mixing of Sr and Hg on the same crystallographic position (Tkachuk and Mar, 2008). This, in fact, is rather common for this structure type – similar disorder has been observed in Eu_11-xHg_54+x (Tambornino and Hoch, 2015; Zaremba et al., 2024), which is isostructural to Sr_11-xHg_54+x. The exact mechanism of change in stoichiometry between different samples of SrHg₈ and SrHg₁₁ is less clear. For SrHg₈, single crystal X-ray diffraction analysis did not reveal any disorder present (Tkachuk and Mar, 2010). For SrHg₁₁, only powder X-ray diffraction data was previously analyzed (Biehl and Deiseroth, 1999). In general, in complex compounds with mercury, chemical disorder is enabled by a large number of possible positions for mercury as well as other elements (Svanidze et al., 2019; Tambornino et al., 2015). Crystal structures of both SrHg₈ and SrHg₁₁ are rather complex and have many crystallographic sites. However, in the current study, it was not possible to carry out single crystal diffraction experiments, which could perhaps elucidate the mechanism(s) behind the variation of the lattice parameters in SrHg₈ and SrHg₁₁.

It is important to note that the values of the upper critical fields $H_{c2}$ for SrHg₁₁, SrHg₈, and Sr₁₀Hg₅₅ are about an order of magnitude larger than those observed for other conventional, BCS-type mercury-based superconductors such as LaHg_6.4 ($H_{c2}=0.061$ T (Prots et al., 2022a)), Lu/ScHg₃ ($H_{c2}=0.08$ T (Witthaut et al., 2023)), as well as elemental Hg ($H_{c2}=0.04$ T (Finnemore et al., 1960)). However, given that for all three compounds the values of $H_{c2}$ are significantly below the Pauli limit (Clogston, 1962; Chandrasekhar, 1962) (4.09 T for Sr₁₀Hg₅₅, 5.58 T for SrHg₈, and 5.95 T for SrHg₁₁), it is most likely that the superconductivity of these materials is conventional. Typically, the values of the specific heat jump, as well as the electron-phonon coupling constant can be extracted from the specific heat data, which in this case was not possible. Another argument in favor of conventional superconductivity of strontium mercurides is the robustness of superconductivity to the crystallographic disorder. However, further investigations of the superconducting strontium mercurides, in particular Sr₁₀Hg₅₅, are of interest, given the noncentrosymmetric crystal structure of this compound. Superconductors that lack inversion symmetry can often host a variety of peculiar phenomena (Naskar et al., 2021; Tanaka et al., 2023; Chirolli et al., 2022; Smith et al., 2021), even if their critical temperatures and fields are relatively low. As we have shown previously, a complementary analysis of specific heat and muon spin relaxation, rotation, and resonance ($\mu$SR) can be used to comprehensively understand these systems (Khasanov et al., 2020a; Khasanov et al., 2020b; Beare et al., 2019; Amon et al., 2018).

4 Conclusion

The mercury-strontium compounds were revisited with the emphasis on the mercury-rich phases for two reasons: (i) conflicting reports regarding existing phases and (ii) a possibility of finding new superconductors. The reformulation of the system was made possible by implementing differential thermal analysis coupled with powder X-ray diffraction experiments. Existence of SrHg₁₁, SrHg₈, Sr₁₀Hg₅₅, SrHg₂, SrHg, Sr₃Hg₂, and Sr₃Hg was confirmed.

The physical properties of all phases were probed down to $T=1.8$ K. While the majority of strontium mercurides are paramagnetic or diamagnetic, three new superconductors have been identified: SrHg₁₁ ($T_c=3.2\pm 0.3$ K, $H_{c2}=0.18\pm 0.05$ T), SrHg₈ ($T_c=3.0\pm 0.1$ K, $H_{c2}=0.35\pm 0.02$ T), and Sr₁₀Hg₅₅ ($T_c=2.2\pm 0.25$ K, $H_{c2}=0.54\pm 0.05$ T). While the critical fields are higher than those of other mercury-based superconductors, the superconductivity of SrHg₁₁, SrHg₈, and Sr₁₀Hg₅₅ is likely conventional. However, future investigations of the superconducting state in Sr₁₀Hg₅₅ by means of muon spin relaxation, rotation, and resonance is warranted, given its noncentrosymmetric crystal structure.

Data availability statement

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.

Author contributions

RN: Conceptualization, Data curation, Methodology, Visualization, Writing–original draft, Writing–review and editing. YP: Data curation, Investigation, Methodology, Writing–review and editing. MK: Data curation, Investigation, Methodology, Visualization, Writing–review and editing. NZ: Data curation, Investigation, Methodology, Writing–review and editing. OP: Data curation, Writing–review and editing. MS: Data curation, Investigation, Methodology, Writing–review and editing. LA: Data curation, Investigation, Writing–review and editing. YG: Data curation, Investigation, Methodology, Writing–review and editing. ES: Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Project administration, Supervision, Validation, Writing–original draft, Writing–review and editing.

Funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. Open access funded by Max Planck Society. RN and ES acknowledge the funding from the International Max Planck Research School for Chemistry and Physics of Quantum Materials and the funding provided by the German Research Foundation (DFG-528628333 “Complex compounds based on mercury”). OP acknowledges financial support from the Polish National Agency for Academic Exchange (NAWA) under the Bekker programme (BPN/BEK/2022/1/00190/U/00001).

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

References

Akselrud, L., and Grin, Y. (2014). WinCSD: software package for crystallographic calculations (Version 4). J. Appl. Crystallogr. 47, 803–805. doi:10.1107/s1600576714001058

CrossRef Full Text | Google Scholar

Amon, A., Svanidze, E., Cardoso-Gil, R., Wilson, M. N., Rosner, H., Bobnar, M., et al. (2018). Noncentrosymmetric superconductor BeAu. Phys. Rev. B 97, 014501. doi:10.1103/PhysRevB.97.014501

CrossRef Full Text | Google Scholar

Beare, J., Nugent, M., Wilson, M., Cai, Y., Munsie, T., Amon, A., et al. (2019). muSR and magnetometry study of the type-I superconductor BeAu. Phys. Rev. B 99, 134510. doi:10.1103/physrevb.99.134510

CrossRef Full Text | Google Scholar

Biehl, E., and Deiseroth, H. J. (1999). Preparation, structural relations, and magnetism of amalgams MHg₁₁ (M: K, Rb, Ba, Sr). Z. fur Anorg. Allg. Chem. 625, 1073–1080. doi:10.1002/CHIN.199938008

CrossRef Full Text | Google Scholar

Bjørklund, G. (1989). The history of dental amalgam. Tidsskr. Nor. Laegeforen 109 (34-36), 3582–3585.

PubMed Abstract | Google Scholar

Bjørklund, G., Dadar, M., Mutter, J., and Aaseth, J. (2017). The toxicology of mercury: current research and emerging trends. Environ. Res. 159, 545–554. doi:10.1016/j.envres.2017.08.051

PubMed Abstract | CrossRef Full Text | Google Scholar

Bruzzone, G., and Merlo, F. (1973). The calcium-mercury system. J. Less-Common Metals 32, 237–241. doi:10.1016/0022-5088(73)90091-X

CrossRef Full Text | Google Scholar

Bruzzone, G., and Merlo, F. (1974). The strontium-mercury system. J. Less Common Metals 35, 153–157. doi:10.1016/0022-5088(74)90154-4

CrossRef Full Text | Google Scholar

Bruzzone, G., and Merlo, F. (1975). The barium-mercury system. J. Less-Common Metals 39, 271–276. doi:10.1016/0022-5088(75)90201-5

CrossRef Full Text | Google Scholar

Canfield, P., and Svanidze, E. (2024). Canfield-Svanidze crucible sets. LSP Industrial Ceramics, Inc. Available at: https://www.lspceramics.com/canfield-svanidze-crucibles/.

Google Scholar

Chandrasekhar, B. S. (1962). A note on the maximum critical field of high-field superconductors. Appl. Phys. Lett. 1, 7–8.

CrossRef Full Text | Google Scholar

Chirolli, L., Mercaldo, M. T., Guarcello, C., Giazotto, F., and Cuoco, M. (2022). Colossal orbital edelstein effect in noncentrosymmetric superconductors. Phys. Rev. Lett. 128, 217703. doi:10.1103/physrevlett.128.217703

PubMed Abstract | CrossRef Full Text | Google Scholar

Claeson, T., and Luo, H. L. (1966). Superconducting transition temperatures of mercury-alkaline earth metal compounds. J. Phys. Chem. solids 27, 1081–1085. doi:10.1016/0022-3697(66)90083-7

CrossRef Full Text | Google Scholar

Clogston, A. M. (1962). Upper limit for the critical field in hard superconductors. Phys. Rev. Lett. 9, 266–267.

CrossRef Full Text | Google Scholar

Conrad, M., Harbrecht, B., Weber, T., Jung, D. Y., and Steurer, W. (2009). Large, larger, largest–a family of cluster-based tantalum copper aluminides with giant unit cells. ii. the cluster structure. Acta Crystallogr. Sect. B Struct. Sci. 65, 318–325. doi:10.1107/s0108768109014013

PubMed Abstract | CrossRef Full Text | Google Scholar

Darmstadt STOE and Cie GmbH (2019). Winxpow.

Google Scholar

Devoto, G., and Recchia, E. (1930). The Sr amalgam. Gazz. Chim. Ital. 60, 688–692.

Google Scholar

Druska, C., Doert, T., and Böttcher, P. (1996). Refinement of the crystal structure of Sr₃Hg₂. Z. fur Anorg. Allg. Chem. 622, 401–404. doi:10.1002/zaac.19966220304

CrossRef Full Text | Google Scholar

Dubois, J.-M., and Belin-Ferré, E. (2010). Complex metallic alloys.

Google Scholar

Ferro, R. (1954). The crystal structures of SrCd, BaCd, SrHg and BaHg. Acta Cryst. 7, 781. doi:10.1107/s0365110x5400240x

CrossRef Full Text | Google Scholar

Finnemore, D., Mapother, D., and Shaw, R. (1960). Critical field curve of superconducting mercury. Phys. Rev. 118, 127–129. doi:10.1103/physrev.118.127

CrossRef Full Text | Google Scholar

Gumiński, C. (2005). The Hg-Sr (mercury-strontium) system. J. Phase Equilibria Diffusion 26, 81–86. doi:10.1361/15477030522590

CrossRef Full Text | Google Scholar

Guntz, A., and Roederer, G. (1906). Sur les amalgames de strontium. Bull. Soc. Chim. Fr. 35, 494–503.

Google Scholar

Hänisch, J., Wimbush, S. C., Berger, L. I., and Roberts, B. W. (2023). “Properties of superconductors,” in CRC handbook of chemistry and physics. Editor J. R. Rumble (Boca Raton, FL: CRC Press/Taylor and Francis).

Google Scholar

Hoch, C. (2019). Mein lieblingselement: quecksilber. Nachrichten aus Chem. 67, 54–60. doi:10.1002/nadc.20194090184

CrossRef Full Text | Google Scholar

Hohl, T., Kremer, R. K., Ebbinghaus, S. G., Khan, S. A., Minár, J., and Hoch, C. (2023). Influence of disorder on the bad metal behavior in polar amalgams. Inorg. Chem. 62, 3965–3975. doi:10.1021/acs.inorgchem.2c04430

PubMed Abstract | CrossRef Full Text | Google Scholar

Kerp, W. (1898). Zur kenntnis der amalgame. Z. Anorg. Chem. 17, 284–309. doi:10.1002/zaac.18980170129

CrossRef Full Text | Google Scholar

Kerp, W., Böttger, W., and Iggena, H. (1900). On the knowledge of amalgams. Z. Anorg. Chem. 25, 1–71. doi:10.1002/zaac.19000250102

CrossRef Full Text | Google Scholar

Khasanov, R., Gupta, R., Das, D., Amon, A., Leithe-Jasper, A., and Svanidze, E. (2020a). Multiple-gap response of type-I noncentrosymmetric BeAu superconductor. Phys. Rev. Res. 2, 023142. doi:10.1103/physrevresearch.2.023142

CrossRef Full Text | Google Scholar

Khasanov, R., Gupta, R., Das, D., Leithe-Jasper, A., and Svanidze, E. (2020b). Single-gap versus two-gap scenario: specific heat and thermodynamic critical field of the noncentrosymmetric superconductor BeAu. Phys. Rev. B 102, 014514. doi:10.1103/physrevb.102.014514

CrossRef Full Text | Google Scholar

König, M., Wiedmann, S., Brüne, C., Roth, A., Buhmann, H., Molenkamp, L. W., et al. (2007). Quantum spin hall insulator state in HgTe quantum wells. Sci. 45, 766–770. doi:10.1126/science.1148047

CrossRef Full Text | Google Scholar

Leithe-Jasper, A., Borrmann, H., and Hönle, W. (2006). Max Planck Institute for chemical Physics of solids, scientific report. Dresden: Max-planck-gesellschaft.

Google Scholar

Naskar, M., Mishra, P., Ash, S., and Ganguli, A. (2021). Superconductors with noncentrosymmetric crystal structures. Bull. Mater. Sci. 44, 278. doi:10.1007/s12034-021-02587-z

CrossRef Full Text | Google Scholar

Pelloquin, D., Hervieu, M., Michel, C., Tendeloo, G. V., Maignan, A., and Raveau, B. (1993). A 94 K Hg-based superconductor with a “1212” structure Hg_0.5Bi_0.5Sr₂Ca_1-xR_xCu₂O_6+δ (R=Nd, Y, Pr). Phys. C Supercond. its Appl. 216, 257–263. doi:10.1016/0921-4534(93)90069-3

CrossRef Full Text | Google Scholar

Prots, Y., Krnel, M., Grin, Y., and Svanidze, E. (2022a). Superconductivity in crystallographically disordered LaHg_6.4. Inorg. Chem. 61, 15444–15451. doi:10.1021/acs.inorgchem.2c01987

PubMed Abstract | CrossRef Full Text | Google Scholar

Prots, Y., Krnel, M., Schmidt, M., Grin, Y., and Svanidze, E. (2022b). Uranium-mercury complex antiferromagnet: UHg_6.4. Phys. Rev. B 106, L060412. doi:10.1103/PhysRevB.106.L060412

CrossRef Full Text | Google Scholar

Roberts, B. W. (1976). Survey of superconductive materials and critical evaluation of selected properties. J. Phys. Chem. reference data 5, 581–822. doi:10.1063/1.555540

CrossRef Full Text | Google Scholar

Samson, S. (1962). Crystal structure of NaCd₂. Nature 195, 259–262. doi:10.1038/195259a0

CrossRef Full Text | Google Scholar

Sappl, J., Freund, R., and Hoch, C. (2017). Stuck in our teeth? crystal structure of a new copper amalgam, Cu₃Hg. Crystals 7, 352. doi:10.3390/cryst7120352

CrossRef Full Text | Google Scholar

Smith, M., Andreev, A., and Spivak, B. (2021). Giant magnetoconductivity in noncentrosymmetric superconductors. Phys. Rev. B 104, L220504. doi:10.1103/physrevb.104.l220504

CrossRef Full Text | Google Scholar

Steurer, W., and Dshemuchadse, J. (2016). Intermetallics: structures, properties, and statistics, vol. 26. Oxford University Press.

Google Scholar

Svanidze, E., Amon, A., Borth, R., Prots, Y., Schmidt, M., Nicklas, M., et al. (2019). Empirical way for finding new uranium-based heavy-fermion materials. Phys. Rev. B 99, 220403R. doi:10.1103/physrevb.99.220403

CrossRef Full Text | Google Scholar

Tambornino, F., and Hoch, C. (2015). The mercury-richest europium amalgam Eu₁₀Hg₅₅. Z. fur Anorg. Allg. Chem. 641, 537–542. doi:10.1002/zaac.201400561

CrossRef Full Text | Google Scholar

Tambornino, F., Sappl, J., and Hoch, C. (2015). The Gd₁₄Ag₅₁ structure type and its relation to some complex amalgam structures. J. Alloys Compd. 618, 326–335. doi:10.1016/j.jallcom.2014.08.017

CrossRef Full Text | Google Scholar

Tanaka, H., Watanabe, H., and Yanase, Y. (2023). Nonlinear optical responses in noncentrosymmetric superconductors. Phys. Rev. B 107, 024513. doi:10.1103/physrevb.107.024513

CrossRef Full Text | Google Scholar

Tkachuk, A. V., and Mar, A. (2008). Alkaline-earth metal mercury intermetallics A_11-xHg_54+x (A = Ca, Sr). Inorg. Chem. 47, 1313–1318. doi:10.1021/ic7015148

PubMed Abstract | CrossRef Full Text | Google Scholar

Tkachuk, A. V., and Mar, A. (2010). In search of the elusive amalgam SrHg₈: a mercury-rich intermetallic compound with augmented pentagonal prisms. Dalton Trans. 39, 7132–7135. doi:10.1039/c0dt00304b

PubMed Abstract | CrossRef Full Text | Google Scholar

Urban, K., and Feuerbacher, M. (2004). Structurally complex alloy phases. J. non-crystalline solids 334, 143–150. doi:10.1016/j.jnoncrysol.2003.11.029

CrossRef Full Text | Google Scholar

Weber, T., Dshemuchadse, J., Kobas, M., Conrad, M., Harbrecht, B., and Steurer, W. (2009). Large, larger, largest–a family of cluster-based tantalum copper aluminides with giant unit cells. i. structure solution and refinement. Acta Crystallogr. Sect. B Struct. Sci. 65, 308–317. doi:10.1107/s0108768109014001

PubMed Abstract | CrossRef Full Text | Google Scholar

Wendorff, M., and Röhr, C. (2018). Alkaline-earth tri-mercurides AIIHg₃ (AII=Ca, Sr, Ba): binary intermetallic compounds with a common and a new structure type. Z. fur Kristallogr. - Cryst. Mater. 233, 515–529. doi:10.1515/zkri-2018-2054

CrossRef Full Text | Google Scholar

Witthaut, K., Prots, Y., Zaremba, N., Krnel, M., Leithe-Jasper, A., Grin, Y., et al. (2023). Chemical and physical properties of YHg₃ and LuHg₃. ACS Org. Inorg. Au 3, 143–150. doi:10.1021/acsorginorgau.2c00048

PubMed Abstract | CrossRef Full Text | Google Scholar

Zaremba, N., Krnel, M., Prots, Y., Sichelschmidt, J., Brando, M., Akselrud, L., et al. (2024). Magnetic properties of Eu₁₀Hg₅₅. in preparation.

Google Scholar