Summary Observation of zero resistance above 100 K in Pb 10-x Cu x PO 4 6 O arxiv.org
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Researchers in China have found a compound that exhibits zero resistance above 100 K, indicating the possibility of high-temperature superconductivity.
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Key Points
- Pb 10-x Cu x (PO 4 ) 6 O displays zero resistance above 100 K under ambient pressure, suggesting possible room-temperature superconductivity.
- The synthesis of Pb 10-x Cu x (PO 4 ) 6 O was achieved using solid-phase synthesis and confirmed through X-ray diffraction.
- The successful synthesis of Pb 10-x Cu x (PO 4 ) 6 O indicates its potential as a high-temperature superconductor candidate.
- Electrical measurements showed a clear zero resistance characteristic at 110 K in sample S1, indicating the possibility of superconductivity.
- The Meissner effect was not observed in the samples, suggesting a relatively low superconducting volume fraction.
Summaries
32 word summary
Researchers at Southeast University in China have discovered zero resistance above 100 K in Pb10-xCux(PO4)6O, suggesting potential for high-temperature superconductivity. The compound was synthesized using Cu powder and P in a 3
179 word summary
Researchers from the Department of Physics at Southeast University in China have observed zero resistance above 100 K in a material called Pb 10-x Cu x (PO 4 ) 6 O, indicating the possibility of high-temperature superconductivity. Super
The synthesis process of Pb10-xCux(PO4)6O was conducted using a mixture of Cu powder and P in a molar ratio of 3:1. The mixture was sealed in high vacuum quartz tubes and heated to 550
The X-ray diffraction patterns of precursor materials and the target product of Pb 10-x Cu x (PO 4 ) 6 O were analyzed. The successful synthesis of Pb 10-x Cu x (PO 4 ) 6 O was
This summary reports on the observation of zero resistance above 100 K in the compound Pb 10-x Cu x (PO 4 ) 6 O. The study conducted electrical measurements on sample S1, which showed a clear zero resistance characteristic at
Superconductivity has been observed at high temperatures in various compounds, including iron-based compounds, rare-earth-doped compounds, and hydrogen-rich compounds. Examples include superconductivity at 55 K in Sm[O 1-x F x ]FeAs
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Observation of zero resistance above 100 K in Pb 10-x Cu x (PO 4 ) 6 O
Qiang Hou 1,2 , Wei Wei 1,2 , Xin Zhou 1,2 , Yue Sun 1 , Zhixiang Shi 1
1
Department of Physics, Southeast University, Nanjing 211189, China
Abstract：Room-temperature superconductivity has always been regarded as the ultimate goal in
the fields of solid-state physics and materials science, with its realization holding revolutionary
significance, capable of triggering significant changes in energy transmission and storage. However,
achieving it poses various challenges. Recent research revealed that material Pb 10-x Cu x (PO 4 ) 6 O
displays room-temperature superconductivity under atmospheric pressure, sparking global interest
in further exploration. Here, we utilized solid-phase synthesis to obtain a polycrystalline sample of
Pb 10-x Cu x (PO 4 ) 6 O. X-ray diffraction confirmed its structural consistency with referenced literature.
Zero resistance, which is an important evidence for superconductivity, was observed above 100 K
under ambient pressure in our experiment. Our finding indicates that Pb 10-x Cu x (PO 4 ) 6 O is a possible
candidate for searching high-temperature superconductor.
Introduction
Superconductivity, first observed in 1911, has fascinated scientists due to its unique properties
[1]. It has significantly impacted various fields, from fundamental physics research to practical
applications like magnetic resonance imaging (MRI) machines and particle accelerators [2,3,4,5].
However, one defining limitation stood firmly in the way of its widespread implementation - the
requirement of ultra-low temperatures to achieve the superconducting state. Therefore, over a
century, lots of scientists have mad great efforts to search superconductors with higher transition
temperature, T c . The cuprate superconductors with T c over 150 K and iron-based superconductors
with T c over 50 K have been discovered subsequently [6,7,8,9,10]. In 2015, SH 3 was reported to
show T c ~203 K at a pressure of 155 GPa [11 ,12 ,13 ], then the superconductivity has been
discovered in YH 9 and LaH 10 at 243 K and 260 K under ~ 200 GPa [14,15,16,17]. In March 2023,
Gammon et al reported evidence of near ambient (1 GPa) superconductivity in lutetium-hydrogen-
nitrogen, which attracts worldwide attention [18]. However, its reliability is still under debate [19].
Until now, the room temperature superconductor at ambient pressure has not been confirmed yet.
1 Department of Physics, Southeast University, Nanjing 211189, China.
2 These authors contributed equally: Qiang Hou, Wei Wei, Xin Zhou. e-mail: [email protected]; [email protected] recently, room-temperature superconductivity with T c ~ 400 K at ambient pressure has been
reported in Cu-doped lead-apatite Pb 10-x Cu x (PO 4 ) 6 O (0.9 < x < 1.1) [20,21]. It is a very excited news
for both the research community and the industry. However, more evidence for the
superconductivity need to be confirmed. In this report, we successfully synthesized the Pb 10-
x Cu x (PO 4 ) 6 O
compound, and observed the zero resistance above 100 K, which is an important
evidence for superconductivity.
Experiment
In this manuscript, we synthesized polycrystalline sample of Pb 10-x Cu x (PO 4 ) 6 O using solid-
state sintering. The first step in this experiment involves synthesizing the precursor Lanarkite and
Cu 3 P. First of all, to obtain Lanarkite, a 1:1 stoichiometric mixture of high-purity Pb(SO) 4 powder
(Aladdin 99.99%) and PbO powder (Aladdin 99.999%) was thoroughly mixed by grinding for one
hour. Subsequently, the mixture was placed in two separate containers: a quartz tube under high
vacuum and an alumina crucible exposed to air. The mixture was placed in a muffle furnace and
heated to 725℃ at a rate of 3 ℃/min for 24 hours. We discovered that the mixture sintered in air
ultimately transforms into phase Pb 3 O 2 SO 4 , whereas the mixture sealed in a high-vacuum quartz
tube transforms into phase Lanarkite Pb 2 (SO 4 )O. Specific analysis can be found in the next section.
To synthesize Cu 3 P, the following chemical equation is used: 3Cu + P → Cu 3 P. Cu powder (Aladdin
99.9%) was thoroughly mixed with P (Aladdin 99.999%) in a molar ratio of 3:1 inside a Glovebox
filled with argon. The mixture was sealed into high vacuum quartz tubes, slowly heated to 550 °C
at a rate of 3 ℃/min, and then kept in a furnace for 48 hours to obtain the precursor Cu 3 P.
In order to synthesize Pb 10-x Cu x (PO 4 ) 6 O, we designed four different ratios for our experiment:
2Pb 2 (SO 4 )O +2Cu 3 P→Pb 10-x Cu x (PO 4 ) 6 O (S1);
2Pb 3 O 2 SO 4 +2Cu 3 P→Pb 10-x Cu x (PO 4 ) 6 O (S2);
4.5Pb 2 (SO 4 )O +6Cu 3 P→Pb 10-x Cu x (PO 4 ) 6 O (S3);
4.5Pb 3 O 2 SO 4 +6Cu 3 P→Pb 10-x Cu x (PO 4 ) 6 O (S4).
The batching and grinding processes are conducted inside a Glovebox filled with argon.
Subsequently, the mixture was compressed into 8 mm cylindrical blocks at 6GPa and sealed in a
high vacuum quartz tube. Finally, four evenly mixed raw materials were obtained. These uniformly
mixed pellets were raised to a temperature of 925 °C at a rate of 1.5 °C/minute, held for 10 or 20
hours, and then cooled in a furnace to obtain our target product Pb 10-x Cu x (PO 4 ) 6 O.
The crystal structure of produced samples was examined using an X-ray diffractometer (XRD)
with Cu-Kα radiation on a Bruker D8 Discover diffractometer. The in-plane electrical resistivity
was carried out by the standard four-probe method on a physical property measurement system(PPMS, Quantum Design). Magnetization measurement was preformed by the VSM (vibrating
sample magnetometer) option of PPMS.
Results and Discussion
Figure 1 shows the XRD patterns of the precursors Cu 3 P and Pb 2 (SO 4 )O, along with all the
synthesized products. The data for Cu 3 P in Fig. 1(a) is in complete agreement with the standard
PDF card from software jade 6.5, indicating the pure phase without impurities. For the precursor
Pb 2 (SO 4 )O, the formation of Pb 2 (SO 4 )O and Pb 3 O 2 SO 4 were observed under sintering mixture of
Pb(SO) 4 and PbO in air and vacuum, respectively. To examine the impact of precursor ratios on the
final product, we prepared four samples, namely S1, S2, S3, and S4, each with different precursors
and ratios, as detailed in Table 1. In Fig. 1(c), the powder XRD patterns of S1 and S2 exhibit
identical peak positions, as do those of S3 and S4, suggesting that the choice of precursor,
Pb 2 (SO 4 )O or Pb 3 O 2 SO 4 , has limited effect on the target product. Instead, the peaks of S1 and S3
(or S2 and S4) are almost completely different, indicating that the ratio of precursors Pb 2 (SO 4 )O:
Cu 3 P (or Pb 3 O 2 SO 4 : Cu 3 P) is the key to the synthesis of samples.
(a)
(b)
(c)
½PDF#74-1067
sintering in air
Pb 3 O 2 SO 4
½ PDF#78-2419
Precursor
Cu 3 P
S1
S2
sintering in vaccum
Pb 2 (SO 4 )O S3
½ PDF#33-1486 S4
10 20 30 40 50 60 70 80 90
10
20
30
40
50
60
70
80
90
2θ (deg)
2θ (deg)
Fig. 1 X-ray diffraction patterns of (a) precursor Cu 3 P, (b) Pb 2 (SO 4 )O (sintering in vacuum),
Pb 3 O 2 SO 4 (sintering in air), and (c) target product of Pb 10-x Cu x (PO 4 ) 6 O.
TABLE 1. Precursors and ratio of four samples.
Pb 2 (SO 4 )O: Cu 3 P
Pb 3 O 2 SO 4 : Cu 3 P
1: 1
S1
S2
4.5: 6
S3
S4To validate the successful synthesis of Pb 10-x Cu x (PO 4 ) 6 O, Figure 2 displays the XRD patterns
of the sample in ref. [21] and S1. Remarkably, the XRD diffraction peaks of sample S1 are
consistent with the ref. [21], and on this basis, the phase formation has been improved, with no
distinct CuS 2 peak observed. It provides a strong evidence for the successful synthesis of Pb 10-
x Cu x (PO 4 ) 6 O.
Moreover, high-quality samples guarantee the accuracy of the results we obtained.
(a)
arXiv 2307.12037
(b)
XRD of sample S1
10 20 30 40 50 60 70 80 90
2θ (deg)
Fig. 2 X-ray diffraction patterns of (a) ref. [21] and (b) sample S1.
(a)
0.01
(b)
I = 1 mA
T czero = 110 K
0.1
0.01
0.001
0.001
1E-4
9 T
7 T
5 T
3 T
1 T
0 T
1E-4
1E-5
1E-5
1E-6
1E-6
1E-7
0
50
100
150
T (K)
200
250
300
1E-7
50
100
150
T (K)
Fig 3. (a) Temperature dependence of resistance for sample S1 pallet; (b) Temperature
dependence of resistance for sample S1 under magnetic fields from 0 to 9 T.
200In order to further investigate the physical properties of Pb 10-x Cu x (PO 4 ) 6 O, we conducted
electrical measurements on sample S1, which was divided into several small pieces. Due to the
fragility of the samples, it is difficult to cut them into regular shape. Therefore, we selected some
small pieces for measurement, as shown in the insert of Figure 3(a). Fig. 3(a) shows the temperature
dependence of resistance sample S1, with a clear zero resistance characteristic observed at 110 K,
indicating the possibility of superconductivity. It is worth noting that some other pieces exhibit
semiconductor behavior, consistent with the literature [22]. Above 250K, two significant resistance
jumps are clearly observed, and the temperature-rise and cooling measurement curves perfectly
coincide. It is not clear what is the cause of these large jumps, which may be due to the influence
of the electrode contact. We also measured the temperature dependence of resistance under fields
ranging from 0 to 9 T, as shown in Fig. 3 (b). Inset shows the image of the measured sample S1
with electrodes attached. As the applied magnetic field increases to 5 T, T onset
is gradually suppressed,
c
but T zero
still reaches more than 110 K. When the magnetic field is increased to more than 7 T, the
c
resistance trend is abnormal, which is contrary to normal superconductors that the external
magnetic field will simply reduce the critical temperature of superconductivity. The specific reason
needs our further study. More importantly, the zero resistance is robust under magnetic field, which
indicates possible large upper critical field in this material. To further verify the superconducting
properties, we conducted magnetic measurements on the sample, but unfortunately, no obvious
Meissner signal was observed, indicating that the superconducting volume fraction of the sample
may be very small. The preparation of high-purity samples are still a challenging task.
Conclusion
In conclusion, we successfully synthesized the compound Pb 10-x Cu x (PO 4 ) 6 O, and observed the
zero resistance above 100 K. However, the Meissner effect has not been observed yet in our samples,
which suggests that the superconducting volume is relatively low. We still need more evidences to
confirm the superconductivity, and to identify which component is in charge of the zero resistance
(superconductivity). Besides, whether the T c could be enhanced up to room temperature is still an
open question.
Acknowledge
This work was partly supported by the National Key R&D Program of China (Grant No.
2018YFA0704300), the Strategic Priority Research Program (B) of the Chinese Academy of
Sciences (Grant No. XDB25000000), and the National Natural Science Foundation of China (Grant
No. U1932217).Reference
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