S1

Structural, magnetic, and optical properties of A3V4(PO4)6 (A = Mg, Mn, Fe, Co, Ni) – Supporting Information

Spencer H. Porter†, Jie Xiong

&, Maxim Avdeev

♯, David Merz

†, Patrick M. Woodward

&,*, Zhenguo

Huang†,*

†Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW, Australia 2522

♯Bragg Institute, Australian Nuclear Science and Technology Organization, Menai, NSW 2234 Australia

&The Ohio State University, Dept. of Chemistry & Biochemistry, 100 W. 18th Ave, Columbus, OH 43210

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Rietveld Refinement of XRD data Final XRD Rietveld refinements for A3V4(PO4)6 where A is Mg (Figure S1), Mn (Figure S2), Fe (Figure S3), Co (Figure S4), and Ni (Figure S5) led to a P-1 space group assignment. To minimize correlations, rigid bodies were used to model the PO4

3– tetrahedra. Thermal parameters were not refined and were instead set to reasonable values. Rietveld refinement on XRD data for A3V4(PO4)6 where A is Mg, Mn – Ni resulted in respective 1.07 (weighted profile R-factor, Rwp = 14.5), 1.14 (11.5), 1.25 (3.5), 1.05 (6.5), and 1.09 (14.7) goodness-of-fit values. Incident X-rays generated background fluorescence, resulting in elevated noise, making adequate fits challenging.

10 20 30 40 50 602θ (°)

Inte

nsi

ty (

a.u

.)

Figure S1: Rietveld refinement of laboratory XRD data for Mg3V4(PO4)6. Observed (black dots), calculated (red), difference (blue), and Bragg peaks (green hashes) are compared.

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10 20 30 40 50 602θ (°)

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nsi

ty (

a.u

.)

Figure S2: Rietveld refinement of laboratory XRD data for Mn3V4(PO4)6. Observed (black dots), calculated (red), difference (blue), and Bragg peaks (green hashes) are compared.

10 20 30 40 50 602θ (°)

Inte

nsi

ty (

a.u

.)

Figure S3: Rietveld refinement of laboratory XRD data for Fe3V4(PO4)6. Observed (black dots), calculated (red), difference (blue), and Bragg peaks (green hashes) are compared.

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10 20 30 40 50 602θ (°)

Inte

nsi

ty (

a.u

.)

Figure S4: Rietveld refinement of laboratory XRD data for Co3V4(PO4)6. Observed (black dots), calculated (red), difference (blue), and Bragg peaks (green hashes) are compared.

10 20 30 40 50 602θ (°)

Inte

nsi

ty (

a.u

.)

Figure S5: Rietveld refinement of laboratory XRD data for Ni3V4(PO4)6. Observed (black dots), calculated (red), difference (blue), and Bragg peaks (green hashes) are compared.

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Combined SXRD and NPD refinements Combined Rietveld refinements of synchrotron and neutron powder diffraction data were carried out for A3V4(PO4)6, where A is Mg (Figure S6), Fe (Figure S7), Co (Figure S8), and Ni (Figure S9). Unidentified peaks were detected and identified during Rietveld refinement of synchrotron data (Table S1). In Mg3V4(PO4)6 they are attributed to V2O3, but in the remaining A3V4(PO4)6 compounds, the peaks did not produce matches to any known compounds in the ICSD. The NPD fit for Ni3V4(PO4)6 has unaccounted peaks at 2θ = 64, 120.5, and 145°, but these are presumed to be from secondary phase contributions as well. Atomic positions resulting from those refinements for A3V4(PO4)6, where A is Mg (Table S2), Mn (Table S3), Fe (Table S4), Co (Table S5), and Ni (Table S6), are reported.

Table S1: Secondary phase peaks observed in SXRD patterns. The most intense peak (*) is noted.

3.66 3.83 6.635 4.9 5.792.715* 3.31* 6.18 3.26* 5.49*2.475 3.065 5.78 3.22 5.25

5.485* 3.08 4.225.27 2.45 2.754.225 1.61 2.213.923.6653.573.5253.43.213.083.0252.842.7452.635

Mg3V

4(PO

4)6

Mn3V

4(PO

4)6

Fe3V

4(PO

4)6

Co3V

4(PO

4)6

Ni3V

4(PO

4)6

d-spacing (Å)

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Figure S6: Combined room temperature NPD (top) and SXRD (bottom) Rietveld refinements of Mg3V4(PO4)6. Observed (black dots), calculated (red), difference (blue), Bragg peaks (green hashes), secondary phases (purple triangles) and vanadium can (purple hashes) are compared.

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Figure S7: Combined room temperature NPD (top) and SXRD (bottom) Rietveld refinements of Fe3V4(PO4)6. Observed (black dots), calculated (red), difference (blue), indexed peaks (green hashes), secondary phases (purple triangles), and vanadium can (purple hashes) are compared.

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Figure S8: Combined room temperature NPD (top) and SXRD (bottom) Rietveld refinements of Co3V4(PO4)6. Observed (black dots), calculated (red), difference (blue), indexed peaks (green hashes), secondary phases (purple triangles), and vanadium can (purple hashes) are compared.

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Figure S9: Combined room temperature NPD (top) and SXRD (bottom) Rietveld refinements of Ni3V4(PO4)6. Observed (black dots), calculated (red), difference (blue), indexed peaks (green hashes), secondary phases (purple triangles), and vanadium can (purple hashes) are compared.

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Table S2: Room temperature combined SXRD and NPD derived atomic parameters for Mg3V4(PO4)6.

ion site x y z occ Uiso (Å2)

Mg1/V1 1a 0 0 0 0.738/ 0.262(4) 0.00278(4) Mg2 2i 0.2833(4) 0.8137(3) 0.2895(3) 1 0.00278(4)

V3/Mg3 2i 0.3885(3) 0.4628(2) 0.1156(2) 0.934/0.066(2) 0.00278(4) V4/Mg4 2i 0.9525(2) 0.2848(2) 0.4784(1) 0.934/0.066(2) 0.00278(4)

P1 2i 0.2244(4) 0.1422(3) 0.7694(2) 1 0.0037(4) P2 2i 0.0879(4) 0.5893(3) 0.8344(3) 1 0.0037(4) P3 2i 0.6087(4) 0.7694(3) 0.6329(3) 1 0.0037(4)

O1 2i 0.2251(5) 0.1983(4) 0.9448(4) 1 0.0091(3) O2 2i 0.5458(6) 0.6309(4) 0.7153(4) 1 0.0091(3)

O3 2i 0.0133(6) 0.1856(4) 0.6590(4) 1 0.0091(3)

O4 2i 0.1049(6) 0.7878(4) 0.9184(4) 1 0.0091(3)

O5 2i 0.7338(6) 0.9628(4) 0.7689(4) 1 0.0091(3)

O6 2i 0.3733(5) 0.7734(4) 0.5090(4) 1 0.0091(3)

O7 2i 0.0572(5) 0.5432(4) 0.6497(4) 1 0.0091(3)

O8 2i 0.4566(6) 0.2596(4) 0.7707(4) 1 0.0091(3)

O9 2i 0.8734(6) 0.4579(4) 0.8368(4) 1 0.0091(3)

O10 2i 0.7606(6) 0.7222(5) 0.5373(4) 1 0.0091(3)

O11 2i 0.2096(5) 0.9401(4) 0.7063(4) 1 0.0091(3)

O12 2i 0.3088(6) 0.5398(4) 0.9185(4) 1 0.0091(3)

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Table S3: Atomic positions, site occupation, and thermal parameters of room temperature Mn3V4(PO4)6.

Atom Site x y z occ Uiso (Å2)

Mn1/V1 1a 0 0 0 0.964/0.036(8) 0.0044(4) Mn2 2i 0.2853(1) 0.8177(1) 0.2898(1) 1 0.0044(4)

V3/Mn3 2i 0.3852(2) 0.4618(1) 0.1130(1) 0.991/0.009(8) 0.0044(4) V4/Mn4 2i 0.9547(2) 0.2862(1) 0.4740(1) 0.991/0.009(8) 0.0044(3)

P1 2i 0.2208(3) 0.1477(2) 0.7631(2) 1 0.00354(5) P2 2i 0.0962(3) 0.5928(2) 0.8347(2) 1 0.00354(5) P3 2i 0.6037(3) 0.7624(2) 0.6352(2) 1 0.00354(5) O1 2i 0.2182(5) 0.2084(4) 0.9378(4) 1 0.0065(3)

O2 2i 0.5509(5) 0.6325(4) 0.7215(4) 1 0.0065(3) O3 2i 0.0125(5) 0.1834(4) 0.6487(4) 1 0.0065(3) O4 2i 0.8796(5) 0.4613(4) 0.8375(4) 1 0.0065(3)

O5 2i 0.7283(5) 0.9522(4) 0.7628(4) 1 0.0065(3)

O6 2i 0.3655(5) 0.7576(4) 0.5106(4) 1 0.0065(3)

O7 2i 0.0630(5) 0.5369(4) 0.6491(4) 1 0.0065(3)

O8 2i 0.4558(5) 0.2729(4) 0.7714(4) 1 0.0065(3)

O9 2i 0.3105(5) 0.5383(4) 0.9217(4) 1 0.0065(3)

O10 2i 0.7526(5) 0.7074(4) 0.5366(4) 1 0.0065(3) O11 2i 0.2074(5) 0.9494(4) 0.7037(4) 1 0.0065(3) O12 2i 0.1265(5) 0.7881(4) 0.9182(4) 1 0.0065(3)

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Table S4: Room temperature combined SXRD and NPD derived atomic parameters for Fe3V4(PO4)6.

ion site x y z occ Uiso (Å2)

Fe1/V1 1a 0 0 0 0.95/0.05(1) 0.00333(6) Fe2 2i 0.2823(3) 0.8155(2) 0.2917(2) 1 0.00333(6)

V3/Fe3 2i 0.3875(4) 0.4612(3) 0.1141(3) 0.987/0.013(6) 0.00333(6)

V4/Fe4 2i 0.9554(4) 0.2861(3) 0.4752(3) 0.987/0.013(6) 0.00333(6) P1 2i 0.6012(5) 0.7641(4) 0.6326(4) 1 0.0051(5) P2 2i 0.0946(5) 0.5925(4) 0.8361(4) 1 0.0051(5) P3 2i 0.2261(5) 0.1447(4) 0.7642(4) 1 0.0051(5)

O1 2i 0.3613(9) 0.7539(7) 0.5071(7) 1 0.0076(5)

O2 2i 0.2089(8) 0.9446(7) 0.7036(7) 1 0.0076(5)

O3 2i 0.5529(9) 0.6362(7) 0.7227(7) 1 0.0076(5)

O4 2i 0.1236(8) 0.7928(7) 0.9202(7) 1 0.0076(5)

O5 2i 0.4548(9) 0.2705(7) 0.7704(7) 1 0.0076(5)

O6 2i 0.2224(8) 0.2053(7) 0.9403(7) 1 0.0076(5)

O7 2i 0.8753(9) 0.4671(7) 0.8382(7) 1 0.0076(5)

O8 2i 0.7549(9) 0.7128(7) 0.5403(7) 1 0.0076(5)

O9 2i 0.3104(9) 0.5415(7) 0.9189(7) 1 0.0076(5)

O10 2i 0.0161(9) 0.1807(7) 0.6535(7) 1 0.0076(5)

O11 2i 0.7247(8) 0.9628(7) 0.7611(7) 1 0.0076(5)

O12 2i 0.0626(9) 0.5431(7) 0.6526(7) 1 0.0076(5)

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Table S5: Room temperature combined SXRD and NPD derived atomic parameters for Co3V4(PO4)6.

ion site x y z occ Uiso (Å2)

Co1/V1 1a 0 0 0 0.752/0.248(9) 0.00092(4) Co2 2i 0.2915(2) 0.8145(2) 0.2923(1) 1 0.00092(4)

V3/Co3 2i 0.3883(3) 0.4624(2) 0.1146(2) 0.938/0.062(5) 0.00092(4)

V4/Co4 2i 0.9543(3) 0.2847(2) 0.4789(2) 0.938/0.062(5) 0.00092(4) P1 2i 0.2207(4) 0.1411(4) 0.7677(3) 1 0.0080(5) P2 2i 0.0905(4) 0.5895(4) 0.8320(3) 1 0.0080(5) P3 2i 0.6111(4) 0.7694(4) 0.6350(3) 1 0.0080(5)

O1 2i 0.2280(7) 0.2012(7) 0.9476(5) 1 0.0099(4)

O2 2i 0.0123(8 0.6300(7) 0.7154(5) 1 0.0099(4)

O3 2i 0.0122(8) 0.1810(7) 0.6578(5) 1 0.0099(4)

O4 2i 0.8711(8) 0.4556(7) 0.8344(5) 1 0.0099(4)

O5 2i 0.7334(7) 0.9646(7) 0.7655(5) 1 0.0099(4)

O6 2i 0.3705(8) 0.7677(5) 0.5079(5) 1 0.0099(4)

O7 2i 0.0653(7) 0.5435(7) 0.6514(5) 1 0.0099(4)

O8 2i 0.4557(8) 0.2649(7) 0.7732(5) 1 0.0099(4)

O9 2i 0.3130(8) 0.5414(7) 0.9230(7) 1 0.0099(4)

O10 2i 0.7569(8) 0.7199(7) 0.5365(5) 1 0.0099(4)

O11 2i 0.2115(7) 0.9411(7) 0.7083(5) 1 0.0099(4)

O12 2i 0.1081(7) 0.7863(7) 0.9196(5) 1 0.0099(4)

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Table S6: Room temperature combined SXRD and NPD derived atomic parameters for Ni3V4(PO4)6.

ion site x y z occ Uiso (Å2)

Ni1/V1 1a 0 0 0 0.531/0.469(9) 0.00239(5) Ni2 2i 0.2765(3) 0.8101(2) 0.2854(2) 1 0.00239(5)

V2/Ni3 2i 0.3931(4) 0.4629(3) 0.1181(3) 0.883/0.117(5) 0.00239(5)

V3/Ni4 2i 0.9556(4) 0.2831(3) 0.4787(3) 0.883/0.117(5) 0.00239(5) P1 2i 0.2268(5) 0.1391(4) 0.7716(4) 1 0.0057(6) P2 2i 0.0876(6) 0.5917(4) 0.8353(4) 1 0.0057(6) P3 2i 0.6017(5) 0.7695(4) 0.6323(4) 1 0.0057(6)

O1 2i 0.2260(9) 0.1935(7) 0.9511(7) 1 0.0079(6)

O2 2i 0.539(1) 0.6271(7) 0.7068(7) 1 0.0079(6)

O3 2i 0.012(1) 0.1786(7) 0.6646(7) 1 0.0079(6)

O4 2i 0.121(1) 0.7904(7) 0.9199(7) 1 0.0079(6)

O5 2i 0.7326(9) 0.9594(7) 0.7702(7) 1 0.0079(6)

O6 2i 0.367(1) 0.7667(7) 0.5017(7) 1 0.0079(6)

O7 2i 0.054(1) 0.5454(8) 0.6519(7) 1 0.0079(6)

O8 2i 0.455(1) 0.2581(7) 0.7733(7) 1 0.0079(6)

O9 2i 0.8697(9) 0.4567(7) 0.8368(7) 1 0.0079(6)

O10 2i 0.762 (1) 0.7214(8) 0.5347(7) 1 0.0079(6)

O11 2i 0.2169(9) 0.9395(8) 0.7073(7) 1 0.0079(6)

O12 2i 0.306(1) 0.5361(7) 0.9205 (7) 1 0.0079(6)

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Magnetization measurements:

χ(T) (left vertical axis) and χ–1(T) (right vertical axis) for A3V4(PO4)6, where A is Mg (Figure S10), Mn (Figure S11), Fe (Figure S12), and Ni (Figure S13,) convey adherence to Curie-Weiss behavior and indicate the ordering temperature and magnetic character. Coercivity was also probed for the A3V4(PO4)6 series of compounds, where A is Mn (Figure S14), Fe (Figure S15), and Ni (Figure S16).

Figure S10: χ(T) (left y-axis) and χ–1(T) (right y-axis) for Mg3V4(PO4)6. Measured under 1000 Oe.

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Figure S12: χ(T) (left y-axis) and χ–1(T) (right y-axis) for Fe3V4(PO4)6. Measured under 1000 Oe.

Figure S11: χ(T) (left y-axis) and χ–1(T) (right y-axis) for Mn3V4(PO4)6. Measured under 1000 Oe.

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Magnetization of A3V4(PO4)6

The isothermal magnetization at 5 K for A3V4(PO4)6 (Figure S14 – S17) shows linear responses consistent with an antiferromagnetic ground state. The irreversibility displayed by Fe3V4(PO4)6 is attributed to a tiny amount of unidentified ferromagnetic impurity.

Figure S13: χ(T) (left y-axis) and χ–1(T) (right y-axis) for Ni3V4(PO4)6. Measured under 1000 Oe.

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Figure S15: Isothermal magnetization of Fe3V4(PO4)6.

Figure S14: Isothermal magnetization of Mn3V4(PO4)6.

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Figure S16: Isothermal magnetization of Co3V4(PO4)6.

Figure S17: Isothermal magnetization of Ni3V4(PO4)6.

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Kubelka-Munk UV-visible diffuse reflectance:

To help elucidate the contributions of individual d-d transitions, the Kubelka-Munk UV-visible diffuse reflectance was collected for the starting materials (Figure S18). The charge transfer between the non-bonding 2p oxygen atoms and the phosphorous 3p is the most prominent feature for all compounds at energies greater than 335 nm. At lower energies the d-d transitions, are only seen in the A = Co and Ni starting compounds. For Co, there are two peaks at 480 and 580 nm, the former which is a 5-coordinate transition from the trigonal bipyramidal site (4A2 → 4E’’(P)) while the later is two octahedral peaks close together (4T1g → 4T1g(P), 4T1g → 4A2g(F)). In Ni3(PO4)2 there are more peaks (430, 470, 710, 820 nm) and assignment is complicated by the fact that both octahedral and trigonal bipyramidal peaks are expected within similar ranges. However, the 430 nm peak is assigned to the 3A2g → 3T1g(P) octahedral transition while the 820 nm peak is assumed to arise from the combination of the 3A2g → 1Eg(D) and 3A2g → 3T1g(F) octahedral transitions. The 470 and 710 nm peaks are assigned to the trigonal bipyramidal transitions 3E’ → 3A2’(P) and 3E’ → 3A2’(F). The reasoning behind these assignments is that the larger, wider peaks would belong to the octahedral transitions given the prominence of their spin forbidden transitions and greater distortion, while the trigonal bipyramidal transitions would be smaller.

Figure S18: Kubelka-Munk UV-visible diffuse

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reflectance of a) Co3(PO4)2 and b) Ni3(PO4)2 and c) the remaining phosphate starting materials. Bond parameter data: To help evaluate structure property relations, combined SXRD and NPD diffraction were used to generate average polyhedral bond distances (Table S7) and Baur’s D (Table S8).

Mg3V4(PO4)6 Mn3V4(PO4)6 Fe3V4(PO4)6 Co3V4(PO4)6 Ni3V4(PO4)6

M1-O 2.109(3) 2.200(3) 2.181(5) 2.130(4) 2.096(5) M2-O 2.034(4) 2.120(3) 2.086(6) 2.042(5) 2.025(6) M3-O 2.011(4) 2.005(3) 1.998(6) 1.997(5) 2.014(6) M4-O 1.991(4) 2.002(3) 2.001(6) 2.001(5) 2.001(6) P1-O 1.556(4) 1.563(3) 1.552(6) 1.560(5) 1.552(6) P2-O 1.553(4) 1.561(4) 1.550(6) 1.561(5) 1.549(6) P3-O 1.556(4) 1.551(3) 1.553(6) 1.554(5) 1.559(6)

Table S7: Average bond distances (Å) in A3V4(PO4)6.

Table S8: A3V4(PO4)6 polyhedral distortion indices (Baur's D).

Mg3V4(PO4)6 Mn3V4(PO4)6 Fe3V4(PO4)6 Co3V4(PO4)6 Ni3V4(PO4)6

M1-O 0.0415 0.0303 0.0464 0.0408 0.0242 M2-O 0.0135 0.0181 0.0228 0.0204 0.0116 M3-O 0.0232 0.0243 0.0245 0.0209 0.0217 M4-O 0.0300 0.0265 0.0305 0.0285 0.0416 P1-O 0.0113 0.0141 0.0095 0.0224 0.0169 P2-O 0.0135 0.0209 0.0134 0.0147 0.0181 P3-O 0.0077 0.0157 0.0177 0.0147 0.0173