Intermetallics of 4:4:1 and 3:3:1 series in La – (Co,Ni) – M ( M = Bi, Pb, Te, Sb, Sn and Ga, Al) systems and their properties ☆

Two series of isostructural intermetallics have been discovered in our search for new compounds with fused honeycomb motifs, both stable at elevated temperatures (1073 K). They crystallize with orthorhombic unit cells – La 4 Co 4 M ( M = Sn, Sb, Te, Pb, Bi, SG Pbam , a = 8.247 – 8.315(2), b = 21.913 – 22.137(7), c = 4.750 – 4.664(2) Å, V = 850.5 – 869.5(4) Å 3 , Z = 4) and La 3 Ni 3 M ( M = Al, Ga, SG Cmcm , a = 4.1790 – 4.2395(1), b = 10.4921 – 10.6426 (6), c = 13.6399 – 13.7616(8) Å, V = 606.72 – 612.05(7), Z = 3). The crystal structures represent interesting variations of semiregular tilings of corrugated anionic layers and predominantly cationic zigzag motifs. The La 4 Co 4 M compounds reveal a complex type of ordering with a high degree of frustration as could be expected for the Kagom ´ e -related lattices, while magnetic ordering in the La 3 Ni 3 M series is less evident. Electronic structure calculations have been performed for multiple compounds within both series revealing metallic character and visible local minima around the Fermi level. The bonding picture is characterized by nearly equal contributions from the anionic and the cationic components.


Introduction
Polar intermetallic compounds have been extensively investigated exhibiting broad compositional variability and enormous structural complexity [1].While usually polar intermetallics include a wide range of compounds extending from the metal alloys to Zintl compounds [2], considerable attention has been paid to the middle range, compounds with the valence electron count of around 2 [3,4].This group is mostly represented by ternary compounds including active or rare-earth metals, transition metals and a p-block element including some metalloids [5][6][7][8].Among them, trielides and tetrelides are the most frequent and offer a plethora of structural motifs of all dimensionalities, i.e. from clusters to networks and peculiar bonding features [1].Besides compositional wealth such element combination is also interesting in terms of properties.Superconductivity has been detected for many p elements and their compounds, e.g. the majority of the La-Sn binary compounds [9][10][11].On the other hand, rare earth elements, with their high number of unpaired f-electrons, are most important for introducing magnetism.Adding transition metals allows, aside from magnetism, to add additional features including electronic and geometric adjustments leading to interesting properties and unique property combinations.For example, though containing a magnetic element Co, LaCoSi exhibits superconductivity at 4 K [12].It is also known as a catalyst for NH 3 production [13].
Despite the number of discovered compounds, their physical or chemical properties have been investigated to an even lesser extent.The most interesting are ferromagnetism in La 6 Co 13 M [15] and La 4 Co 2 Sn 5 [22], low thermal conductivity in the La-filled cobalt antimonide Skutterudites La x Co 4 Sb 12 [43], superconductivity in La 3 Co 4 Sn 13 , and largely positive and nonsaturating magnetoresistance of La 2 NiGa 12 [32].Some other compounds, e.g.LaNi 4 Ga [44] or LaNi 4 Al [45] showed good hydrogen sorption efficiency.In the latter case, hydrogenation influenced the magnetic properties leading to ferromagnetism [46].LaNi 3 Ga 2 reveals spin fluctuation [47] while excellent MCE (magnetocaloric effect) performance has been observed in a series of R 2 T 2 X [48].Magnetic properties have also been inspected in LaNi 0.75 Ga 3.25 [49], LaNiAl 2 [50], R 2 Ni 2 Ga and R 2 Ni 2 Al [27].
In the present work, we explored two series of isotypic ternary compounds in the La-(Co,Ni)-M systems i.e.La 4 Co 4 M and La 3 Ni 3 M (M = Bi, Pb, Te, Sb, Sn and Ga, Al).Although isocompositional compounds are quite common in these systems, it is interesting to note that the discovery of the La 4 Co 4 M series brought us to the fact that such types of compounds can be obtained with 'antagonistic pairs' [51] (like Co-Pb or Co-Bi).Following the structural studies, magnetic behavior as well as electronic structures have been investigated for both series.

Experimental part and theoretical methods
The La 4 Co 4 Sn and La 3 Ni 3 M (M= Ga and Al) alloys (1 g each) were synthesized by arc-melting of high purity La (99.9%),Ni and Co (99.99%),Sn, Ga and Al (99.999%) with further annealing at 1073 K in vacuum.The observed weight losses never exceeded 0.5%.The La 4 Co 4 M (M= Bi, Pb, Te and Sb) alloys were prepared from arc-melted La 4 Co 4 ligature and Bi, Pb, Te and Sb (all with 99.9% purity) powders to avoid evaporation losses during melting.The ligatures were crushed and mixed with the respective M-metals.Such mixtures were loaded into Ta tubes and sealed under Ar atmosphere.Ta tubes were afterward placed in stainless steel tubes to protect them from oxidation.The samples were heated up to 1073 K for 10 h, kept for 10 h at 1073 K and cooled to 773 K at 3 K/h.Final cooling has been performed by switching off the furnace.
Intensity data sets for powder X-ray diffraction (PXRD) were recorded at room temperature using a Bruker D8 X-ray diffractometer with a Lynx-eye position sensitive detector and Cu-Kα radiation on a zerobackground single crystal Si sample holder.Phase analyses using the Rietveld method [52] of the powder X-ray data were performed using Topas 6 software [53].Rietveld refinements of selected samples are presented in Supporting Information (SI) Fig. S1.
Single-crystal X-ray diffraction (SСXRD) data were collected at 293 K on a Bruker D8 Venture diffractometer (Bruker, USA; Photon 100 CMOS detector, IμS microfocus source: Mo K α radiation, λ = 0.71073 Å, 2 -5).Intensity data sets of reflections and scaling were integrated within the APEX3 software package by using SAINT [54].Absorption corrections were conducted with SADABS [55] and crystal structure solutions with SHELXT [56].For subsequent difference, Fourier analyses and least-squares refinements, SHELXL-2013 [57] was used.The experimental details of the crystal structure determination and refinement as well as the atomic coordinates for La 4 Co 4 Bi and La 3 Ni 3 Ga as representative examples have been collected in Tables 1 and 2.
The microstructure was evaluated with a Zeiss Merlin SEM equipped with a secondary electron (SE) detector and an energy-dispersive X-ray (EDX) spectrometer.The samples for electron microscopy analysis were prepared by standard metallographic techniques through grinding with SiC paper.For the final polishing, a mixture of SiO 2 and H 2 O was used.SEM micrographs are presented in Fig. S2.
Magnetization measurements were conducted using a Physical Property Measurement System (PPMS, Quantum Design, USA).Vibrating Sample Magnetometer (VSM) options were utilized to measure zero-field cooled (ZFC) and field-cooled (FC) magnetization between 2 and 300 K in static fields (DC) up to 7 T. Isothermal magnetization was acquired in applied fields up to 7 T. Polycrystalline samples were filled into polypropylene (PP) capsules, which were mounted into a brass sample holder.
The First-Principles calculations have been led in a similar way to the previous work [58], using the VASP code [59,60], i.e. the electronic properties were determined through Density Functional Theory (DFT) using a pseudopotential approach within the projector augmented-wave (PAW) method, employing collinear spin polarization.The Perdew-Burke-Ernzerhof (PBE) functional [61] in the generalized gradient approximation (GGA), was employed with a cutoff energy of 600 eV.Structural relaxations, encompassing volume, cell shape, and atomic positions, were performed while maintaining the original symmetry, with a convergence criterion set at forces less than 0.05 meV per Å.Сrystal orbital Hamiltonian population (COHP) curves were extracted by the Lobster program [62].Subsequently, phonon calculations were conducted within the harmonic approximation for La 3 Ni 3 Ga and La 4 Co 4 Bi using a supercell approach (2 ×2 ×1, 1 ×1 ×2 respectively), as implemented with the Phonopy code [63].Charge transfer analyses were carried out following Bader's method [64].

Crystal structures
As to the extent of our knowledge, the intriguing hexagonal honeycomb-like structure motifs extending along the 6(3)-fold axis were first observed in La 15 Ni 13 Bi 5 [58], we extended our explorations onto chemically closely related systems.Although identical motifs could not be observed in any of them, two isostructural series were identified, i.e.La 4 Co 4 M (M = Bi, Pb, Te, Sb and Sn) and La 3 Ni 3 M (M = Ga and Al).Both of them crystallize with orthorhombic unit cells though different space groups, Pbam and Cmcm, respectively (Table 1).While La 3 Ni 3 M are ordered ternary representatives of the Er 3 Ge 4 type [65], La 4 Co 4 M are the first representatives of their own type of structure.
The crystal structure of La 4 Co 4 Bi (as a representative of the La 4 Co 4 M series) is best described in terms of relatively separated Co and Bi layers well in line with the antagonistic nature [51] of this pair stacking along the b axis (Fig. 1).Bi atoms form zigzag chains along the a axis being surrounded by La equatorially tricapped prisms.Such a zigzag sequence of the prisms also leaves tetrahedral voids appearing like a distorted (3.6) 2 Kagomé -like ribbon.It is worth noting that such a p-element-centered trigonal prism is a common structural element in an extended family of intermetallics, though they usually condense forming larger triangular conglomerates with an edge size of up to six units [66,67].It is interesting that unit cell of La 4 Co 4 M contracts from Sn to Sb and Te, however, the unit cell shape change is strongly anisotropic where the a parameter is the least affected, the b expands and the c contracts (Table 1).
The cobalt layer represents a slightly corrugated augmented Kagomé lattice (Fig. 1  The crystal structure of La 3 Ni 3 Ga exhibits analogous puckered but polyanionic layers separated by the layers of edge-sharing square pyramids.The latter extend along the a axis but alternate their orientation   [78].From the common features, we must outline that the homoatomic Co network corrugation in both structures is interconnected with the cationic zigzag motifs.La 2 Co 3 exhibits similar hexagonal motifs though in the form of homogeneous slightly distorted honeycombs along the a axis.Contrary, the lattice in Y 2 Co 2 Ga [69] is planar but composed of two elements and shows a bit different tiling scheme -3 2 6 2 (Fig. 3).Apparently, such a tiling scheme is more resistant and can accommodate corrugated cationic motifs keeping the network planarity.More complex augmented or even sandwiched Kagomé lattices have been observed in the series of intermetallics EuT 5 In (T = Cu, Ni) [79,80] also revealing complex magnetic structures.
Related corrugated tilings with truncated hexagonal fragments may extend to 3 2 10 2 or even 3 2 12 2 (Fig. 3) as observed in the crystal structures of Y 4 Co 4 Ga and Y 5 Co 5 Ga or their derivatives, respectively [81,82].Their corrugations involve multiple truncated hexagons including those with two missing vertices in Y 5 Co 5 Ga with even more differentiated shapes.Each missing vertex is again compensated by a rare-earth atom from the interlayer space.In this series, the planar tiling in Y 2 Co 2 Ga shows the highest degree of distortion and extremely short Co-Co distances suggesting possible underoccupation of some positions.Following the general tendency, all Co-Co-Co angles in the corrugated layers show a minimal degree of distortion not exceeding 3 • from the ideal hexagonal angle.Contrary, the heteroatomic component always leads to a more significant distortion and some stretching of the ribbon (∠ Co-Ga-Co = 112.5-115.5 • ).

Magnetic properties
Magnetic properties of the investigated La 4 Co 4 M with M = Sb, Pb and Bi are presented in Fig. 4. For low measuring fields the properties of La 4 Co 4 Sb were biased by small impurity of La 2 Co 1.7 [83] (Table S1).Therefore, on the Fig. 4a susceptibility measured at 5 T is presented.It shows a distinct anomaly at 170 K suggesting occurrence of antiferromagnetic ordering below that temperature.At lowest temperatures the susceptibility shows a small increase, which presumably is connected to some reorientation of magnetic moments.Inverse susceptibility follows the Curie-Weiss (CW) law down to 220 K, with the paramagnetic Curie temperature (θ CW ) as low as − 79.8(1) K, the effective magnetic moment was found to be 7.0(0) μ B per f.u.Assuming that only Co atoms are magnetic, it means that mean value per Co atoms is about 1.75 μ B , which is close to typical values for low-spin Co 2+ configuration.Isothermal magnetization measured at 2 K shows soft magnetic contribution overlaid on the antiferromagnetic (AF)-like, non-saturating behavior.The soft magnetic properties are likely related to aforementioned rise of magnetic susceptibility at low temperatures.In general, soft magnetic properties are not very surprising as strong AF interaction is usually restricted to Kagomé lattices, whereas inter-planar coupling can be way  weaker, yet even ferromagnetic.
To some extent, the situation evidenced for La 4 Co 4 Pb is similar (Fig. 4b).The departure of ZFC and FC (field cooled) curves observed at 170 K is likely connected to the occurrence of a minority ferromagnetic phase La 6 Co 13 Pb [15], while the real ordering temperature seems to be 30 K. Hysteresis loop collected at 2 K shows an interesting wasp-shape (inset to the Fig. 4b), which occurs for materials with coexistence of components with contrasting coercivities.In our case the exchange bias was not observed, hence interaction with the impurity phase could be excluded.For this reason, this could be attributed to the distribution of magnetic domain sizes, which is likely for heavily frustrated systems.
In contrast to the previous cases, the CW behavior of La 4 Co 4 Bi (Fig. 4c) could not be observed due to the antiferromagnetic impurity phase La 2 Co 3 (T N = 315 K [83]).However, at 50 K irreversibility in FC and ZFC curves arises.As apparent the magnetic susceptibility at small fields as well as magnetization collected at 2 K in the magnetic field of 7 T are very small.The isothermal magnetization shows a small ferromagnetic-like contribution overlaid onto an antiferromagnetic signal.Owing to the saturation of the small hysteresis loop of 0.015 µ B only, one may expect that this suggests non-magnetic (van Vleck paramagnetism) or spin glass properties of the La 4 Co 4 Bi.
Magnetic properties of compounds with triangular arrangements of magnetic atoms (hexagonal, pyrochlore or Kagomé lattices) are usually complex as magnetic frustration may favor second or further neighbors to play a crucial role in the RKKY exchange.This is the case for 4:4:1 family, which exhibits decorated Kagomé motifs built from Co atoms stacked within the ac plane (see Fig. 1).The decoration by out-of-plane Co atoms may introduce additional Dzyaloshinskii-Moriya interaction, which favors complex non-collinear, modulated magnetic structures.Usually, cobalt compounds are ferromagnetic, as long as Co is the only magnetic atom in the lattice.Some exceptions are known mainly in the binary R-Co (R = rare earth) system [83,84].In light of the above, we suggest that the compounds do not exhibit magnetic ordering down to  the lowest temperatures studied due to the complexity of the magnetic interactions.
For the La 3 Ni 3 Al compound, the magnetic susceptibility shows no Curie-Weiss behavior, as well as the modified one, in the investigated temperature range (Fig. 5a).The susceptibility shows a broad maximum at about 37 and 22 K for ZFC and FC curves, respectively.Additionally, small departure between the FC and ZFC curves can be noticed below roughly 250 K.However, the collected magnetization curves (inset to Fig. 5a) show an extremely small signal.Measurements performed at higher magnetic fields of 5 T revealed that the sample shows temperature independent behavior above 25 K.The discrepancy between low and high field data is a clear sign that the above-mentioned anomalous behavior originates from spurious phases.This is by isothermal magnetization curves, which shows small ferromagnetic signal with saturation of 0.005 µ B only.It can be presumably associated with traces of pure nickel, hence, ferromagnetic precipitations.Taking above into account the sample can be classified as the van Vleck paramagnet.
For the La 3 Ni 3 Ga alloy, the magnetic susceptibility shows temperature-independent behavior between 200-380 K with hysteresis loops typical of weak paramagnet with extremely small values of magnetic moment (Fig. 5b).The low-temperature part of the susceptibility shows a small maximum at about 51 K, which is presumably related to the traces of the La 2 Ni 7 impurity phase, which was reported to order antiferromagnetically at that temperature [85].The measurements performed at higher magnetic fields did not reveal substantial changes, apart from flattering the curve above 100 K. Additionally, the inverse susceptibility does not follow the Curie-Weiss behavior, which suggests that the sample is van Vleck paramagnet, as well.Below 25 K the magnetic susceptibility shows some rise, which may originate from some traces of pure Ni precipitations at the grains boundaries, as the isothermal magnetization shows some small ferromagnetic component with the saturation moment less than 0.0007 µ B .For both compounds, the lack of the long-range magnetic ordering along with Curie-Weiss behavior is in agreement with electronic structure calculations discussed below.

Electronic structures
To gain a better understanding of the composition-structureproperty relationships in the investigated compounds, band structure calculations have been performed.The initial sets of structural parameters for the selected La   V. Shtender et al.
Table 3.The optimized average volume is comparable to the experimental ones, with a small underestimation (usually not exceeding 1%), though not expected when using the PBE exchange and correlation functional.
Using spin relaxation, only the Co-based compounds converged to a distinguishable ferromagnetic ordering with a weak magnetic moment of about 0.2 μ B /at., mainly held by the Co atoms in 8i and 2d positions (0.9 μ B /at.), with a small ferrimagnetic contribution from La. Several magnetic orders, such as antiferromagnetic, have been tested on the Nibased compounds, all falling to a Pauli paramagnetic, within the pseudopotential approximation.All these spin polarization results show a good agreement with the experimental measurement, where the Ni-based compounds hardly reveal any magnetic ordering.For the Co-based compound, as in the measurement, the calculation shows that the Co atoms hold the major magnetic contribution.The total moment is slightly different, which can be explained by the pseudopotential approximation used.
The electronic DOS is shown in Fig. 6.For all compounds, a small structure around 6 to 8 eV below the Fermi level corresponds to the hybridized sp bands of the M element, while the valence structure is mainly composed of the 3d elements.The filling of these dense bands could be clarified with the Bader analysis, and the corresponding electronic charge transfer is given in Table 3.While La allows to give about 1 electron, the 3d element fills its bands by grabbing 0.7 electrons for Co and 0.9-1.2 for Ni.Since Ni reveals practically filled 3d bands in both spin directions, it serves as a good explanation for the absence of magnetism for both Ni-based compounds.It can be noted that the s-p elements such as Sb, Bi and Pb capture about 1.5 electrons thanks to their highest electronegativity, whereas Al, the worst electronegative, even gives electrons to the system, especially to fill the Ni-3d bands as explained earlier.
The heat of formation, Δ f H, for all compounds has been calculated and shows a value around − 40 kJ/mol, as usual for the intermetallics of La with transition elements [86].The mechanical stability has been studied in the harmonic approximation.As an example, the phonon dispersion curves of La 4 Co 4 Bi and La 3 Ni 3 Ga present no imaginary frequencies (Fig. 7).The M element has acoustic branches in common with Co/Ni, while the heavier atom, La, vibrates at lower frequencies.The La 4 Co 4 Bi presents a vibrational contribution center of the Bi, as the s-p element, located at lower frequencies compared with the Ga, due to the respective weight.4) due to the isolation of the Sn positions.La-La contributions in both structures are comparable as well (Fig. 9).

Conclusions
Two isostructural series, La 4 Co 4 M (M = Sn, Sb, Te, Pb, Bi) and La 3 Ni 3 M (M = Al, Ga) have been synthesized.Both series are characterized by interesting variations of the semiregular tilings of the corrugated anionic layers combined with predominantly cationic zigzag motifs.The layers in La 4 Co 4 M are of augmented Kagomé type with a minimal degree of corrugation, while those in La 3 Ni 3 M have a more complex tiling (3 2 8 2 ) and a more significant degree of corrugation.In Magnetic characterization has been performed for both series.For La 4 Co 4 M compounds, we were unable to prove long-range magnetic ordering due to strong magnetism from impurity phases.Only for the La 4 Co 4 Sb, complex antiferromagnetic ordering below 170 K was suggested.However, it seems that the other compounds show rather weak, frustrated magnetism, if any.No magnetic ordering in the La 3 Ni 3 M series was evidenced.The magnetic susceptibility was found to be temperature independent with no Curie-Weiss behavior, which is likely a sign of van Vleck paramagnetism.From the electronic structure study, the partial charge transfer from La to the other elements explains the filling of the 3d-Ni bands and the corresponding absence of magnetism for Ni-based compounds.
The electronic densities of states of La

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(right)) separating the triangular La/Bi motifs.Due to additional capping Co atoms (yellow), Co hexagons and triangles show a little different degree of distortion with Co-Co distances 2.3544-2.4326(8)Å and 2.3544-2.5211(8)Å, respectively.It is worth noting that none of these distances exceed the sum of two covalent radii of Co (1.27 Å) [68].The Co-Co-Co angles within the hexagons do not deviate significantly from the ideal 120 • angle -119.3-121.7(1)and 117.8-124.3(1)• , however, the angles between the neighboring hexagons along the a axis are 143.4(1)• , quite noticeably deviating from planarity.

Fig. 1 .
Fig. 1.Projection of the crystal structure of La 4 Co 4 Bi on the ab plane (left) and Co Kagomé lattice (right).La atoms are green and lavender, Coorange and yellow, and Biblue.

Fig. 2 .
Fig. 2. Projection of the crystal structure of La 3 Ni 3 Ga on the bc plane (left) and Co/Ga 3 2 8 2 lattice (right).La atoms are green and lavender, Niorange and Ga blue.

Fig. 4 .
Fig. 4. Magnetic properties of La 4 Co 4 M with M=Sb (a), Pb (b), and Bi (c).Field-cooled (FC) and Zero field-cooled (ZFC) curves were measured in the field of 0.01 T, except for La 4 Co 4 Sb, where 5 T magnetic field was used.Isothermal magnetization loops collected at 2 K are presented in the insets.For the La 4 Co 4 Sb compound inverse susceptibility was plotted in the inset to part (a), along with the Curie-Weiss fit (red line).

Fig. 5 .
Fig. 5. Magnetic properties of La 3 Ni 3 Al (a) and La 3 Ni 3 Ga (b).Zero field cooled (ZFC) curves were measured in a field of 0.01 T and 5 T. Inserts show isothermal magnetization curves measured at several temperatures.

4
Co 4 M (M = Bi, Sb and Pb) and La 3 Ni 3 M (M = Ga and Al) have been relaxed and the optimized data have been provided in

Fig. 6 .
Fig. 6.Electronic density of states with partial contribution of each atom for both spin directions of La 4 Co 4 M (M=Bi, Sb, Pb) and La 3 Ni 3 M (M=Ga, Al) compounds.

Fig. 8 .
Fig. 8. -COHP curves of the six types of bonds in the crystal structure of La 3 Ni 3 Ga.Only selected La-Ni, La-Ga and La-La bonds have been plotted for clarity purposes.The Fermi level is indicated by a dotted line.
some sense larger (8 2 ) fragments exist of two truncated hexagons and the corrugation is required to keep the optimized Co-Co-Co bonding angles (~120 • ) within the polyanionic layer.The discovery of the La 4 Co 4 M series brought us to the fact that such types of compounds can be obtained with 'antagonistic pairs' i.e.Co-Pb or Co-Bi.As for the La 3 Ni 3 M compounds, it is only the second observation of such a structure containing La and the first one within R-Ni-M (R= rare earth element, M = Ga and Al) systems.

4
Co 4 M show extensive overlaps, large mostly Co-d states dominating at 0-4 eV below the Fermi level and local minima at E F .Predominantly M-p states could be observed at − 8 eV or below.As for La 3 Ni 3 M large Ni-d states are less broad dominating at 1.5-2.5 eV, while the M-p states are located at 6-7 eV below E F .The bonding picture in both series is qualitatively and quantitatively similar showing enhanced contribution from the La pairs.Even though heteroanionic pairs could not be observed in La 4 Co 4 M total contribution from both anionic pairs in La 3 Ni 3 M is equal to the Co-Co contribution.Similarly, contributions from the La-La pairs are not negligible in both compounds giving ~6% in total.CRediT authorship contribution statement Vitalii Shtender: Writingoriginal draft, Supervision, Methodology, Investigation.Smetana Volodymyr: Writingoriginal draft, Supervision, Investigation.Crivello Jean-Claude: Writingoriginal draft, Investigation.Kravets Anatolii: Writingreview & editing, Investigation, Formal analysis.Gondek Łukasz: Writingoriginal draft, Formal analysis.Mudring Anja-Verena: Writingreview & editing, Formal analysis.Sahlberg Martin: Writingreview & editing, Resources.

Fig. 9 .
Fig. 9. -COHP curves of (left) all Co-Co bonds and (right) three representative La-Co, La-Sn and La-La bonds in the crystal structure of La 4 Co 4 Sn.The Fermi levels are indicated by dotted lines.

Table 1
Crystallographic data and experimental details of the structure determination for the La 4 Co 4 M and La 3 Ni 3 M (M = Bi, Pb, Te, Sb, Sn and Ga, Al).Experiments were carried out at 293 K with Mo Kα radiation.

Table 2
Atomic coordinates and equivalent isotropic displacement parameters for the La 4 Co 4 Bi and La 3 Ni 3 Ga compounds as representative models for the corresponding isostructural series.

Table 3
Relaxed cell parameters after DFT Calculation, Total magnetic moment, Heat of formation and average Bader charge by atom.

Table 4
Bond length ranges, average -ICOHP values and total contributions to bonding interactions in La 3 Ni 3 Ga and La 4 Co 4 Sn.