5 Magnetization Plateau of a 2D Layered

Article Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX

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Syntheses, Structure, and 2/5 Magnetization Plateau of a 2D Layered Fluorophosphate Na3Cu5(PO4)4F·4H2O Xiaoyu Yue,† Zhongwen Ouyang,*,† Meiyan Cui,‡ Lei Yin,† Guiling Xiao,† Zhenxing Wang,† Juan Liu,† Junfeng Wang,† Zhengcai Xia,† Xiaoying Huang,‡ and Zhangzhen He*,‡ †

Wuhan National High Magnetic Field Center & School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China ‡ State Key Laboratory of Structure Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, People’s Republic of China S Supporting Information *

ABSTRACT: A new two-dimensional (2D) fluorophosphate compound Na3Cu5(PO4)4F·4H2O with a Cu5 cluster has been synthesized using a conventional hydrothermal method. The compound crystallizes in the orthorhombic crystal system with space group Pnma. The 2D layered structure is formed by cap-like {Cu5(PO4)4F} building units consisting of a Cu4O12F cluster plus a residual cap Cu2+ ion. Magnetic susceptibility exhibits a broad maximum at T2 = 19.2 K due to low-dimensional character followed by a long-range antiferromagnetic ordering at T1 = 11.5 K, which is further confirmed by the specific heat data. High-field magnetization measurement demonstrates a 2/5 quantum magnetization plateau above 40 T. The ESR data indicate the presence of magnetic anisotropy, in accordance with the 2D structure of the system.

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performance.21−23 BaCuPO4Cl, as a member of another fluorophosphates family AMPO4F (A = divalent alkaline earth metal), exhibits a honeycomb-like copper phosphate framework.24 Recently, two new compounds BaCuPO4F and BaCoPO4F were synthesized. Magnetization measurements showed that the Cu compound is paramagnetic down to 2 K, whereas the Co compound exhibits an antiferromagnetic (AFM) ordering at 11.3 K.25 Thus, the transition metal fluorophosphate not only is an idea platform for structural chemistry research but also provides opportunities for finding new interesting magnetic behaviors. On the basis of phosphoric groups, our current motivation is to constitute new 2D Cu-based magnetic compounds. In this paper, a new transition metal fluorophosphate compound Na3Cu5(PO4)4F·4H2O with a 2D corrugated layered structure has been successfully synthesized by a hydrothermal method. The magnetic susceptibility, specific heat, pulsed-high-field magnetization, and electron spin resonance (ESR) have been employed to investigate the magnetism of Na3Cu5(PO4)4F· 4H2O. As a result, the compound undergoes a susceptibility maximum at 19.2 K due to low-D character and a long-range magnetic ordering at 11.5 K. At 2 K, a field-induced 2/5 magnetization plateau with a magnetic moment of 0.45 μB/ Cu2+ is observed above 40 T.

INTRODUCTION Low dimensional (D) materials have attracted extensive attention in the area of material science and condensed matter physics because of their fascinating magnetic and electronic phenomena.1−4 In particular, two-dimensional (2D) Cu-based materials formed by a particular lattice always exhibit frustration effects and rich quantum critical behavior.4−6 A famous example is the 2D kagome lattice compound ZnCu3(OH)6Cl2,7−10 which shows no long-range magnetic order at temperatures down to 50 mK due to the strongly geometric frustration and is thus considered one of the best candidates for realizing a spinliquid state. Similar behavior was found in a triangular-lattice compound like Ba3CuSb2O9.11,12 On the other hand, the spin dimer compound BaCuSi2O6 presents a magnetic-field-induced quantum phase transition, e.g., Bose−Einstein condensation,5,13 whereas SrCu2(BO3)2 with a 2D square spin−lattice exhibits multiple magnetization plateaus and is regarded as another typical quantum critical material.14 Although rich quantum effects exist in these systems, exploring and discovering new 2D Cu-based materials is still a challenge for physicists and chemists. Phosphoric groups serve as a link for transition metal polyhedral units, offering a variety of frameworks in structural chemistry. Beyond that, fluorophosphate compounds with the formula A2MPO4F (A = Na, Li; M = Fe, Mn, Co, Ni) present excellent electrochemical properties for promising applications in rechargeable batteries.15−20 In particular, Li2CoPO4F and Li2NiPO4F exhibit favorable stability, cycle reversibility, and high theoretical capacity in high voltage electrochemical © XXXX American Chemical Society

Received: December 20, 2017

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DOI: 10.1021/acs.inorgchem.7b03159 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

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temperature. Specific heat measurement in zero field from 2 to 30 K was performed with a quantum design physical property measurement system (PPMS) on a 10 mg pellet sample. Pulsed-High-Field Magnetization and ESR Measurements. Pulsed-high-field magnetization was detected by the standard inductive method employing a couple of coaxial pickup coils. The pulsed magnetic field up to 55 T with a duration time of 24 ms was generated by using a long-pulse magnet energized by two 0.8 MJ capacitor banks, which are installed at Wuhan National High Magnetic Field Center, China. The pulsed-field ESR spectra were collected in the fieldincreasing process at a frequency range of 50−500 GHz using Gunn oscillators and backward wave oscillators as light sources. Thermal Analysis. Thermogravimetric analysis (TGA) of Na3Cu5(PO4)4F·4H2O was performed in the NETZSCH STA 449F3 instruments under a nitrogen atmosphere at a heating rate of 10 °C min−1. The powdered samples were placed in Al2O3 crucibles and heated from room temperature to 800 °C.

EXPERIMENTAL SECTION

Synthesis. Single crystals of Na3Cu5(PO4)4F·4H2O were synthesized by a conventional hydrothermal method. A 30 mL Teflon liner was charged with 0.6 mmol of Na2C2O4 (AR, 0.0820 g), 0.6 mmol of Cu(NO3)2·3H2O (AR, 0.0690 g), 4 mmol of NaF (AR, 0.1680 g), 0.5 mL of H3PO4, and 6 mL of deionized water. The autoclaves liner was placed into a stainless steel vessel and heated at 230 °C for 4 days under autogenous pressure and then slowly cooled down to room temperature at a rate of ∼2 °C/h for 4 days. The blue sheet crystals of Na3Cu5(PO4)4F·4H2O were obtained by filtering off and washing with water. The powdered samples used for magnetic measurements were prepared by crushing lots of sheet crystals. The purity of the samples was checked by the X-ray diffraction (XRD) technique shown in Figure S1 in the Supporting Information. Electron probe microanalyzer (EPMA) measurement was taken to check the chemical composition of Na3Cu5(PO4)4F·4H2O, which is shown in Table S1 in the Supporting Information. X-Ray Crystallographic Studies. Single crystals of Na3Cu5(PO4)4F·4H2O were mounted on glassy fibers for singlecrystal XRD measurements. Data collections were performed on a Rigaku Mercury CCD diffractometer equipped with graphitemonochromated Mo Kα radiation (λ = 0.71073 Å) at 293 K. The data sets were corrected for Lorentz and polarization factors as well as for absorption by the Multiscan method.26 The structure determination was completed by direct methods and refined by full-matrix least-squares fitting on F2 by SHELX-2016.27 All non-hydrogen atoms were refined with anisotropic thermal parameters. The hydrogen atoms were located at calculated positions and refined with isotropic thermal parameters. The final refined structural parameters were checked on PLATON.28 Crystallographic data and structural refinements are given in Table 1. The final refined atomic positions, important bond lengths, and angles are summarized in Tables S2−S6 in the Supporting Information.

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RESULTS AND DISCUSSION Structural Descriptions. Single-crystal XRD analysis shows that Na3Cu5(PO4)4F·4H2O crystallizes in the orthorhombic crystal system with space group Pnma. The unit-cell parameters are a = 18.655(5) Å, b = 9.685(3) Å, and c = 9.678(3) Å. There are four Cu atoms, two P atoms, three Na atoms, and one F atom in the asymmetric unit. The coordination environments of Cu, P, and Na atoms are shown in Schemes S1−S3 in the Supporting Information. The two P atoms are coordinated by four oxygen atoms forming a slightly distorted PO4 tetrahedron with P−O bond lengths ranging from 1.521(5) to 1.561(5) Å and O−P−O bond angles in the range from 108.3(3) to 112.3(3)o. The Na atoms have three independent crystallographic sites. The Na1 site is surrounded by six oxygen atoms with Na1−O bond lengths in the range from 2.366(8) to 2.415(7) Å. The Na2 site is surrounded by seven oxygen atoms with Na2−O bond lengths in the range from 2.476(8) to 2.612(9) Å, and Na3 is coordinated by only five oxygen atoms with the Na3−O bond lengths in the range from 2.196(29) to 2.687(11) Å. The lesser coordination bond of Na3 may be due to the 1/2 occupation. Cu atoms have four independent crystallographic sites, among which Cu1, Cu3, and Cu4 are coordinated by four oxygen atoms and one fluorine atom, forming a CuO4F tetragonal pyramid with the Cu−O bond length ranging from 1.909(5) to 1.986(5) Å and Cu−F bond length ranging from 2.386(8) to 2.458(8) Å, while Cu2 sites are coordinated by five oxygen atoms with three Cu−O bond lengths: 1.947(6), 1.970(6), and 2.394(9) Å. Meanwhile, the CuO4F tetragonal pyramids are connected to each other by edge-sharing oxygen and fluorine atoms forming a Cu4O12F cluster (see Figure 1a). The Cu4O12F clusters are linked to a CuO4 square plane forming a cap-like {Cu5(PO4)4F} building unit through four PO4 tetrahedra as bridges, as shown in Figure 1b. The valence states of Cu and P calculated by bond valence sum are very close to their postulated oxidation states of +2 and +5, respectively.29 Figure 2 shows the 2D structure of Na3Cu5(PO4)4F·4H2O viewing along the c-axis and a-axis, respectively. The building units {Cu5(PO4)4F} are connected to each other through corner-sharing O atoms of PO4 tetrahedra, forming a 2D corrugated sheet with vacancies. The 2D layers are separated by Na+ and H2O molecules. It is noted that the {Cu5(PO4)4F} building units in the layer are arranged alternatively upward and downward. Each upward or downward {Cu5(PO4)4F} unit is surrounded by four inverted {Cu5(PO4)4F} units. The building unit {Cu5(PO4)4F} of Na3Cu5(PO4)4F·4H2O is similar to the

Table 1. Crystallographic Data and Structural Refinements for Na3Cu5(PO4)4F·4H2O formula formula weight T, K λ, Å space group a, Å b, Å c, Å α, deg β, deg γ, deg volume, Å3 Z density, g cm−3 absorption coefficient, cm−1 GOF R1, wR2 [I > 2σ(I)]a R1, wR2 (all data)

Na3Cu5(PO4)4F·4H2O 857.61 293(2) 0.71073 Pnma 18.655(5) 9.685(3) 9.678(3) 90 90 90 1748.6(9) 4 3.258 0.654 1.027 0.0589, 0.1377 0.0624, 0.1393

R1 = ∑∥Fo | − |F c∥/∑|Fo |, wR2 = {∑w[(Fo )2 − (Fc )2] 2/ ∑w[(Fo)2]2}1/2

a

Magnetization and Specific Heat Measurements. The magnetization measurements of Na3Cu5(PO4)4F·4H2O were carried out by using a superconducting quantum interference device (SQUID) magnetometer with the VSM option. The powdered samples were placed in a gel capsule sample holder suspended in a plastic drinking straw. Temperature-dependent magnetic susceptibility was measured at 0.1 T. Low-temperature isothermal magnetization was measured at 2 K. Before each measurement, the sample was zero-field cooled (ZFC) from the paramagnetic state at 300 K to the desired B


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Inorganic Chemistry

distances of neighboring Cu···Cu in the Cu4O12F cluster are 3.122(1) Å (Cu3···Cu4) and 3.136(1) Å (Cu1···Cu4), meanwhile the distances in the {Cu5(PO4)4F} building units are 4.189(3) Å (Cu2···Cu1), 4.246(2) Å (Cu2···Cu4), and 4.275(3) Å (Cu2···Cu3), respectively. The distances between Cu5 clusters are 3.969(1) Å (Cu3···Cu4) and 3.914(1) Å (Cu1···Cu4). Magnetic Properties. Figure 4a shows the ZFC heating and field-cooled (FC) cooling magnetic susceptibility curves Figure 1. (a) Cu4O12F cluster and (b) cap-like {Cu5(PO4)4F} building units. The symbols are Cu, blue; O, red; F, slivery; P, pink. Here, J is the exchange interactions in the Cu4 clusters through the Cu−O−Cu route, and J′ is the interactions between the cap Cu2 ion and the Cu4 cluster.

Figure 2. 2D layer structure viewed (a) along the c-axis and (b) along the a-axis, in which the CuO4F square-pyramid is blue, the PO4 tetrahedron is pink, and Na ions are yellow.

crown-like building unit {Cu5(PO4)4Cl2} in Sr2Cu5(PO4)4Cl2· 8H2O.30 The difference is that in Sr2Cu5(PO4)4Cl2·8H2O, the Sr2+ cations are located in the center of vacancies, while the Na+ ions in Na3Cu5(PO4)4F·4H2O are located at the noncentral position of the vacancies. The confused arrangement of Na+ ions may induce a reduction of crystal symmetry in Na3Cu5(PO4)4F·4H2O. By removing the nonmagnetic ions Na+, PO43−, F−, and H2O, the topological structure composed by Cu2+ ions forms a 2D spin−lattice in the layer, which is shown in Figure 3. The

Figure 4. (a) The temperature dependence of magnetic susceptibility and the corresponding reciprocal. The blue and green solid lines indicate the calculated curves from exact diagonalization of the Hamiltonian for isolated Cu5 cluster and Cu4 cluster, respectively. The red solid line represents the Curie−Weiss fitting. (b) ZFC and FC susceptibility from 2 to 50 K measured under different fields. The inset of b shows the differential curves d(χT)/dT.

χ(T) measured at 0.1 T. The ZFC curve exhibits a cusp at T1 = 11.5 K, a typical feature of AFM ordering, and a broad maximum at T2 = 19.2 K, a characteristic of low-D antiferromagnet. Furthermore, a significant deviation of the FC cooling curve from the ZFC heating curve appears at T1 = 11.5 K. This thermal hysteresis may originate from weak ferromagnetic interaction in this compound. A typical Curie− Weiss behavior for χ−1(T) is observed above 50 K, giving rise to Curie constant C = 2.41 emu/mol·K and Curie−Weiss temperature θw = −40.66 K, indicating a dominative AFM interactions between Cu2+ ions. The average value of the interactions is estimated to be J/kB = −32 K from θw = −[zS(S + 1)J]/3 (z = 5 is the number of near-neighbor magnetic ions). The calculated effective magnetic moments is 1.97 μB, which is close to the theoretical value of 1.98 μB for free Cu2+ ion with S = 1/2 and g = 2.29 (see below). Figure 4b shows the ZFC and FC curves measured from 2 to 50 K under different magnetic fields. As the magnetic field increases, the ZFC and FC hysteresis below 11.5 K decreases but still exists. A noteworthy feature is that the AFM ordering at 11.5 K has been suppressed

Figure 3. Topological arrangements of magnetic Cu2+ ions viewed on the a−b plane. C


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Inorganic Chemistry

agreement with the magnetic susceptibility data (see Figure 4). The most prominent feature is the well-defined magnetization plateau above 40 T, in which the magnetization remains unchanged up to 55 T. The magnetic moment of the plateau is 0.45 μB/Cu2+, which is 2/5 of the saturation magnetization Ms = 1.15 μB/Cu2+ with g = 2.29 obtained by ESR spectra (see below). We now qualitatively discuss the origin of the observed magnetism. As shown in Figure 1, by comparing with the supersuper-exchange of the Cu−O−P−O−Cu bond in a caplike {Cu5(PO4)4F} building unit (i.e., Cu5 cluster), the nearestneighbor interaction of Cu2+ ions within the Cu5 cluster would originate from the superexchange of the Cu−O−Cu bond in the Cu4O12F unit (i.e., Cu4 cluster). Ignoring the slight difference in Cu···Cu distance through the Cu−O−Cu bond, the four exchange interactions J in the Cu4 clusters can be regarded as identical. These exchange interactions should be larger than those interactions between the cap Cu2 ion and the Cu4 cluster J′. Considering the relative magnitudes of bond lengths, the intercluster interactions are expected to be relatively weaker due to large bond lengths between the clusters. The Hamiltonian with exchange interaction J between two spins is expressed as H = −2JS1·S2. For simplicity, we consider only the dominant AFM interactions J and J′ within the Cu5 cluster, ignoring the complicated and weak intercluster interactions, some of which may be ferromagnetic. As shown in Figure 4a, exact diagonalization of the Hamiltonian for a Cu5 cluster gives a good description of the magnetic susceptibility above 25 K (blue line). The best parameters are J/kB = −24.3 K and J′/kB = −14.4 K. The green line stands for the contribution of the Cu4 cluster, evidencing that the decrease in experimental susceptibility below 19.2 K arises from a spin-singlet state separated from excited states by finite energy gaps. Below 25 K, the interactions between Cu5 clusters influence the magnetic susceptibility, leading to the deviation of the susceptibility from the calculated curve of the isolated Cu5 cluster. The intercluster interactions might lead to AFM ordering at 11.5 K, which is suppressed above 3 T (see Figure 4b). Observation of the 2/5 magnetization plateau in Figure 6 is quite unusual. Simple arrangement of up-spin (u) and downspin (d) gives 1/5 (uuudd) and 3/5 (uuuud) plateaus. From the exact diagonalization of the Hamiltonian, an isolated Cu5 cluster produces 1/5 and 3/5 plateaus without low-field spin gap, while an isolated Cu4 cluster yields a 1/2 plateau with a finite low-field gap. Obviously, the 2/5 plateau is quantum in nature and cannot be explained by an isolated Cu5 or Cu4 cluster. Very recently,32 a theoretical investigation on the spin1/2 Heisenberg octahedral chain with regularly alternating monomeric and square-plaquette sites has predicted the presence of series magnetization plateaus including the 2/5 plateau. The “monomeric and square-plaquette sites” resemble our cap-like Cu5 cluster. Thus, a 2/5 quantum magnetization plateau is expected in our system. Note that quantum magnetization plateaus were observed in many low-D quantum magnets such as multiple plateaus in the spin dimer SrCu2(BO3)2,33 a 1/3 plateau in diamond-chain azurite34 and trimer chain compound Cu3(P2O6OH)2,35 and a 1/2 plateau in the coupled Cu tetramer.36 In our Na3Cu5(PO4)4F·4H2O, the cap-like Cu5 can be considered as coupled clusters. The nearly linear M(H) curve in Figure 6 could arise from the exchange interactions between the Cu5 clusters. For better simulation of the magnetization plateau, information on magnetic structure

above 3 T, while the broad peak at 19.2 K still exists under higher magnetic field. The magnetic phase transitions can be further confirmed by specific heat measurement in zero field. As shown in Figure 5,

Figure 5. Temperature dependence of the specific heat at zero field. The red line shows the phonon contribution. The inset shows the magnetic contribution Cmag and the relationship between magnetic entropy S and temperature.

the curve exhibits a broad anomaly around T2 = 19.2 K due to low-D magnetism. With further decreasing temperature, a λ-like peak appears at T1 = 11.5 K, evidencing the occurrence of longrange AFM ordering. The background specific heat of the phonon can be estimated by fitting the zero-field data above 20 K to a polynomial Cbg = aT3 + bT5 + cT7. The fitted parameters are a = 0.001486 J/K4 mol Cu2+, b = 0.90466 × 10−5 J/K6 mol Cu2+, and c = 1.09436 × 10−9 J/K8 mol Cu2+. The magnetic contribution Cmag can be obtained by subtracting the phonon contribution from the total specific heat data. By integrating Cmag/T from 2 to 30 K, the entropy change is derived to be ΔS = 1.97 J/(mol K), which is close to 34% of S = R ln(2S+1) calculated for the spin-1/2 Cu2+ system, where R is the gas constant. This indicates that a part of magnetic entropy has been lost through long-rang magnetic ordering at 11.5 K. Figure 6 shows the high-field magnetization curve M(H) measured at 2 K calibrated with SQUID data. As seen from the

Figure 6. High-field magnetization curve measured at 2 K calibrated with the SQUID data. The inset shows the magnetization curves measured by SQUID.

inset of Figure 6, the magnetization increases nearly linearly with magnetic field due to AFM character. The curve exhibits an anomaly around 2 T, where a small field hysteresis between the field-increasing and field-decreasing curves is observed. This might be due to the presence of ferromagnetic correlations,31 in D


Article

Inorganic Chemistry Thermal Analysis. Na3Cu5(PO4)4F·4H2O compound up to 800 shown in Figure 8, the

and a set of realistic intercluster interactions is required. The current results on Na3Cu5(PO4)4F·4H2O would stimulate future studies on quantum effects in coupled spin clusters. Pulsed-High-Field ESR. To further investigate the magnetic anisotropy and the spin correlations, we carried out the high-field ESR measurements of Na3Cu5(PO4)4F·4H2O. No resonances were detected below 300 GHz. Figure 7a shows

The thermal stability measurement of has been carried out by heating the °C under a nitrogen atmosphere. As sample is found to be stable when the

Figure 8. TGA and DTG curves for Na3Cu5(PO4)4F·4H2O.

temperature is below 100 °C. There are two main steps of mass loss. As temperature rises, the first remarkable loss of mass starts at T = 100 °C, then a plateau is seen in the temperature range of 150−280 °C. The mass loss is 8.22% from 100 to 150 °C, which is close to the calculated value 8.39% of four water molecules in Na3Cu5(PO4)4F·4H2O. The second step takes place from 280 to 600 °C, corresponding to the release of fluorine, since the mass loss of 2.37% is close to the theoretical value of 2.21% for fluorine in Na3Cu5(PO4)4F·4H2O. The final residuals of thermal analysis are not further characterized because the residuals were melted with a TGA bucket.

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CONCLUSIONS In summary, we have successfully synthesized a new 2D fluorophosphate compound Na3Cu5(PO4)4F·4H2O with a Cu5 cluster by a conventional hydrothermal method. This compound crystallizes in the orthorhombic crystal system with space group Pnma. The topological arrangements exhibit a 2D corrugated layered lattice. The layer is separated by Na+ and H2O molecules. The magnetic and specific heat data confirm that the compound presents a low-D magnetic character at 19.2 K followed by a long-range magnetic ordering at 11.5 K. In the high-field magnetization curve, an unusual 2/5 magnetization plateau has been observed above 40 T. The ESR data indicate the presence of magnetic anisotropy in this 2D layered spin system. Our compound is expected to be a model material for studying a coupled Cu5 cluster with a quantized magnetization plateau.

Figure 7. (a) Temperature-dependent ESR spectra measured at 360 GHz and (b) frequency-dependent ESR spectra measured at 2 K. The inset of b shows the f-H relationship.

the ESR spectra measured at 360 GHz at different temperatures. At 40 K, the paramagnetic resonance peak is very broad with a half-height width of ΔHp = 2.5 T. Such a broad line width is a signature of exchange narrowing due to exchange interaction between Cu2+ ions. The g factor is evaluated to be g = 2.29. When the temperature is lowered, no significant peak shift is observed until T1 = 11.5 K, below which the resonance field shifts to lower field and a new resonance mode appears at 2 K due to the onset of magnetic ordering. Figure 7b shows the frequency-dependent ESR spectra measured at 2 K and the corresponding frequency-field (f-H) relations. The linear mode 2 may correspond to a transition between the singlet state and the first excited state. For mode 1, a zero-field gap of 260 GHz is derived from the extrapolation of the f-H plot, evidencing the presence of anisotropy. Recalling the 2D layer structure, we ascribe the resonance mode to the AFM resonance with easyplane anisotropy. Exact f-H relations for our multisublattice system are not available at this moment. Assuming Δ = 2HEHA , the anisotropy field is estimated as HA = 1.35 K with g = 2.29 and exchange field HE = 24.3 K.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.7b03159. The simulated and experimental powder XRD patterns, atomic coordination environments, quantitative chemical composition analyses, and the final refined atomic positions and structural parameters for Na3Cu5(PO4)4F·4H2O (PDF) Accession Codes

CCDC 1582250 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_ E


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Zvyagin, S. A.; Sasago, Y.; Uchinokura, K. Magnetic-Field-Induced Condensation of Triplons in Han Purple Pigment BaCuSi2O6. Phys. Rev. Lett. 2004, 93, 087203. (14) Kodama, K.; Takigawa, M.; Horvatic, M.; Betthier, C.; Kageyama, H.; Ueda, Y.; Miyahara, S.; Becca, F.; Mila, F. Magnetic Superstructure in the Two-Dimensional Quantum Antiferromanget SrCu2(BO3)2. Science 2002, 298, 395. (15) Ellis, B. L.; Makahnouk, W. R. M.; Makimura, Y.; Toghill, K.; Nazar, L. F. A Multifunctional 3.5 V Iron-Based Phosphate Cathode for Rechargeable Batteries. Nat. Mater. 2007, 6, 749−753. (16) Nagahama, M.; Hasegawa, N.; Okada, S. High Voltage Performances of Li2NiPO4F Cathode with Dinitrile-Based Electrolytes. J. Electrochem. Soc. 2010, 157, A748−A752. (17) Okada, S.; Ueno, M.; Uebou, Y.; Yamaki, J. I. Fluoride Phosphate Li2CoPO4F as a High-Voltage Cathode in Li-Ion Batteries. J. Power Sources 2005, 146, 565−569. (18) Ramesh, T. N.; Lee, K. T.; Ellis, B. L.; Nazar, L. F. Tavorite Lithium Iron Fluorophosphate Cathode Materials: Phase Transition and Electrochemistry of LiFePO4F-Li2FePO4F. Electrochem. Solid-State Lett. 2010, 13, A43−A47. (19) Kim, S. W.; Seo, D. H.; Kim, H.; Park, K. Y.; Kang, K. A Comparative Study on Na2MnPO4F and Li2MnPO4F for Rechargeable Battery Cathodes. Phys. Chem. Chem. Phys. 2012, 14, 3299−3303. (20) Ellis, B. L.; Makahnouk, W. R. M.; Rowan-Weetaluktuk, W. N.; Ryan, D. H.; Nazar, L. F. Crystal Structure and Electrochemical Properties of A2MPO4F Fluorophosphates (A = Na, Li; M = Fe, Mn, Co, Ni). Chem. Mater. 2010, 22, 1059−1070. (21) Khasanova, N. R.; Gavrilov, A. N.; Antipov, E. V.; Bramnik, K. G.; Hibst, H. Structural Transformation of Li2CoPO4F upon LiDeintercalation. J. Power Sources 2011, 196, 355−360. (22) Wang, D.; Xiao, J.; Xu, W.; Nie, Z.; Wang, C.; Graff, G.; Zhang, J.-G. Preparation and Electrochemical Investigation of Li2CoPO4F Cathode Material for Lithium-Ion Batteries. J. Power Sources 2011, 196, 2241−2245. (23) Dumont-Botto, E.; Bourbon, C.; Patoux, S.; Rozier, P.; Dolle, M. Synthesis by Spark Plasma Sintering: A New Way to Obtain Electrode Materials for Lithium Ion Batteries. J. Power Sources 2011, 196, 2274−2278. (24) Etheredge, K. M. S.; Hwu, S. J. A Novel Honeycomb-Like Copper(II) Phosphate Framework, [BaCl][CuPO4]. Inorg. Chem. 1995, 34, 3123−3125. (25) Qiu, C. Q.; He, Z. Z.; Cui, M. Y.; Chen, S. H. Synthesis and Magnetic Properties of Two Isostructural Fluorosphates BaMPO4F (M= Cu, Co) with a Tunnel Structure. Dalton Trans. 2017, 46, 7261. (26) CrystalClear, version 1.3.5; RigakuCrop.: The Woodlands, TX, 1999. (27) Sheldrick, G. M. Crystal Structure Refinement with SHELXL. Acta Crystallogr., Sect. C: Struct. Chem. 2015, 71, 3. (28) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7. (29) (a) Brown, I. D.; Altermatt, D. Bond-Valence Parameters Obtained from a Systematic Analysis of the Inorganic Crystal Structure Batabase. Acta Crystallogr., Sect. B: Struct. Sci. 1985, 41, 244. (b) Brese, N. E.; O’keeffe, M. Bond-Valence Parameters for Solids. Acta Crystallogr., Sect. B: Struct. Sci. 1991, 47, 192. (30) Qiu, C. Q.; He, Z. Z.; Cui, M. Y.; Chen, S. H.; Tang, Y. Synthesis, Structure and Magnetic Properties of New Layered Phosphate Halides Sr2Cu5(PO4)4X2·8H2O (X = Cl, Br) with a Crown-Like Building Unit. Dalton Trans. 2017, 46, 4461. (31) Sanz, F.; Parada, C.; Rojo, J. M.; Ruiz-Valero, C. Synthesis, Structural Chatacterization, Magnetic Properties, and Ionic Conductivity of Na4M∥3(PO4)2(P2O7)(M∥= Mn, Co, Ni). Chem. Mater. 2001, 13, 1334. (32) Strečka, J.; Richter, J.; Derzhko, O.; Verkholyak, T.; Karl’ová, K. Diversity of Quantum Ground States and Quantum Phase Transitions of a Spin-1/2 Heisenberg Octahedral Chain. Phys. Rev. B: Condens. Matter Mater. Phys. 2017, 95, 224415. (33) Matsuda, Y. H.; Abe, N.; Takeyama, S.; Corboz, P.; Honecker, A.; Manmana, S. R.; Foltin, G. R.; Schmidt, K. P.; Mila, F.; Kageyama,

[email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. ORCID

Xiaoyu Yue: 0000-0003-0673-9810 Zhenxing Wang: 0000-0003-2199-4684 Xiaoying Huang: 0000-0002-3514-216X Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (Grant No. 11474110). Z.Z.H. is grateful for the Joint Fund of Research Utilizing Large-scale Scientific Facilities under cooperative agreement between National Natural Science Foundation of China and Chinese Academy of Sciences (No. U1632159). J.F.W. is grateful for support from the National Natural Science Foundation of China (Grant No. 11574098).

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REFERENCES

(1) Anderson, P. W. The Resonating Valence Bond State in La2CuO4 and Superconductivity. Science 1987, 235, 1196. (2) Takada, K.; Sakurai, H.; Takayama-Muromachi, E.; Izumi, F.; Dilanian, R. A.; Sasaki, T. Superconductivity in Two-Dimensional CoO2 Layers. Nature 2003, 422, 53. (3) Kamihara, Y.; Watanabe, T.; Hirano, M.; Hosono, H. Iron-Based Layered Superconductor La[O1‑xFx]FeAs (x = 0.05−0.12) with TC = 26 K. J. Am. Chem. Soc. 2008, 130, 3296. (4) Lee, P. A. An End to the Drought of Quantum Spin Liquids. Science 2008, 321, 1306. (5) Sebastian, S. E.; Harrison, N.; Batista, C. D.; Balicas, L.; Jaime, M.; Sharma, P. A.; Kawashima, N.; Fisher, I. R. Dimensional Reduction at a Quantum Critical Point. Nature 2006, 441, 617. (6) Zapf, V.; Jaime, M.; Batista, C. D. Bose−Einstein Condensation in Quantum Magnets. Rev. Mod. Phys. 2014, 86, 563. (7) Freedman, D. E.; Han, T. H.; Prodi, A.; Müller, P.; Huang, Q. Z.; Chen, Y. S.; Webb, S. M.; Lee, Y. S.; McQueen, T. M.; Nocera, D. G. Site Specific X-ray Anomalous Dispersion of the Geometrically Frustrated Kagome Magnet, Herbertsmithite, ZnCu3(OH)6Cl2. J. Am. Chem. Soc. 2010, 132, 16185. (8) Han, T. H.; Helton, J. S.; Chu, S.; Nocera, D. G.; RodriguezRivera, J. A.; Broholm, C.; Lee, Y. S. Fractionalized Excitations in the Spin-Liquid State of a Kagome-lattice Antiferromagnet. Nature 2012, 492, 406. (9) Shores, M. P.; Nytko, E. A.; Bartlett, B. M.; Nocera, D. G. A structurally Perfect S = 1/2 Kagome Antiferromagnet. J. Am. Chem. Soc. 2005, 127, 13462. (10) Olariu, A.; Mendels, P.; Bert, F.; Duc, F.; Trombe, J. C.; de Vries, M. A.; Harrison, A. 17O NMR Study of the Intrinsic Magnetic Susceptibility and Spin Dynamics of the Quantum Kagome Antiferromagnet ZnCu3(OH)6Cl2. Phys. Rev. Lett. 2008, 100, 087202. (11) Zhou, H. D.; Choi, E. S.; Li, G.; Balicas, L.; Wiebe, C. R.; Qiu, Y.; Copley, J. R. D.; Gardner, J. S. Spin Liquid State in the S = 1/2 Triangular Lattice Ba3CuSb2O9. Phys. Rev. Lett. 2011, 106, 147204. (12) Shanavas, K. V.; Popovic, Z. S.; Satpathy, S. Electronic Structure of Ba3CuSb2O9: A Candidate Quantum Spin Liquid Compound. Phys. Rev. B: Condens. Matter Mater. Phys. 2014, 89, 085130. (13) Jaime, M.; Correa, V. F.; Harrison, N.; Batista, C. D.; Kawashima, N.; Kazuma, Y.; Jorge, G. A.; Stern, R.; Heinmaa, I.; F


Article

Inorganic Chemistry H. Magnetization of SrCu2(BO3)2 in Ultrahigh Magnetic Fields up to 118 T. Phys. Rev. Lett. 2013, 111, 137204. (34) Rule, K. C.; Wolter, A. U. B.; Süllow, S.; Tennant, D. A.; Brühl, A.; Köhler, S.; Wolf, B.; Lang, M.; Schreuer, J. Nature of the Spin Dynamics and 1/3 Magnetization Plateau in Azurite. Phys. Rev. Lett. 2008, 100, 117202. (35) Hase, M.; Matsuda, M.; Kakurai, K.; Ozawa, K.; Kitazawa, H.; Tsujii, N.; Dönni, A.; Kohno, M.; Hu, X. Direct Observation of the Energy Gap Generating the 1/3 Magnetization Plateau in the Spin-1/2 Trimer Chain Compound Cu3(P2O6OD)2 by Inelastic Neutron Scattering Measurements. Phys. Rev. B: Condens. Matter Mater. Phys. 2007, 76, 064431. (36) Lee, S.; Lee, W. J.; van Tol, J.; Kuhns, P. L.; Reyes, A. P.; Berger, H.; Choi, K. Y. Anomalous Spin Dynamics in the Coupled Spin Tetramer System CuSeO3. Phys. Rev. B: Condens. Matter Mater. Phys. 2017, 95, 054405.

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5 Magnetization Plateau of a 2D Layered

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