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A new compound Ce2PtGe3 was synthesized using arc-melting process. The compound crystallizes in an orthorhombic Cmce crystal structure with lattice parameters a = 8.5157(17) A, b = 14.7496(29) A and c = 4.2511(9) A. The structure of Ce2PtGe3 can be derived from the structure of YAlGe, which is another superstructure derivative of the AlB2 prototype crystallizing in the Cmcm space group. The crystal structure of Ce2PtGe3 is composed of infinite arrays of hexagonal [Pt3Ge3] units stacked along the b-axis and the Ce sites are sandwiched between these parallel hexagonal networks, which is closely related to the other known orthorhombic superstructures Ca2AgSi3 (SG: Fmmm) and Ba2LiSi3 (SG: Fddd) in the AlB2 family. Both DC and AC susceptibility measurements reveal a spin glass state probably arising from non-magnetic atomic disorder (NMAD) from positional disorder from a part of Pt and Ge crystallographic sites. This was further supported by specific heat capacity measurements with a high value of γ = 125 mJ mol−1 K−2. The modified Curie–Weiss fitting yielded a residual magnetic moment (χ0) 0.0011 emu mol−1, and Curie paramagnetic temperature, θp = −21.5 K suggesting antiferromagnetic coupling and an effective magnetic moment of 3.09μB per Ce which indicates the presence of Ce3+. A thorough analysis of the temperature dependent resistivity data revealed that the compound might be a Kondo semiconductor at low temperature.

Single crystals (SCs) of the compounds Eu3Ag2In9 and EuCu2Ge2 were synthesized through the reactions run in liquid indium. Eu3Ag2In9 crystallizes in the La3Al11 structure type [orthorhombic space group (SG) Immm] with the lattice parameters: a = 4.8370(1) A, b = 10.6078(3) A, and c = 13.9195(4) A. EuCu2Ge2 crystallizes in the tetragonal ThCr2Si2 structure type (SG I4/mmm) with the lattice parameters: a = b = 4.2218(1) A, and c = 10.3394(5) A. The crystal structure of Eu3Ag2In9 is comprised of edge-shared hexagonal rings consisting of indium. The one-dimensional chains of In6 rings are shared through the edges, which are further interconnected with other six-membered rings forming a three-dimensional (3D) stable crystal structure along the bc plane. The crystal structure of EuCu2Ge2 can be explained as the complex [CuGe](2+δ)– polyanionic network embedded with Eu ions. These polyanionic networks present in the crystal structure of EuCu2Ge2 are shared through the edges of the 011 plane containing Cu and Ge ...

We have demonstrated engineering of the electronic band gap of the hybrid materials based on POMs (polyoxometalates), by controlling its structural complexity through variation in the conditions of synthesis. The pH- and temperature-dependent studies give a clear insight into how these experimental factors affect the overall hybrid structure and its properties. Our structural manipulations have been successful in effectively tuning the optical band gap and electronic band structure of this kind of hybrids, which can find many applications in the field of photovoltaic and semiconducting devices. We have also addressed a common crystallographic disorder observed in Keggin-ion (one type of heteropolyoxometalate [POMs])-based hybrid materials. Through a combination of crystallographic, spectroscopic, and theoretical analysis of four new POM-based hybrids synthesized with tactically varied reaction conditions, we trace the origin and nature of the disorder associated with it and the subtle local structural coordination involved in its core picture. While the crystallography yields a centrosymmetric structure with planar coordination of Si, our analysis with XPS, IR, and Raman spectroscopy reveals a tetrahedral coordination with broken inversion symmetry, corroborated by first-principles calculations.

The compounds Eu 5 In 2 Sb 6 and Yb 5 X 2 Sb 6 ( X = Al, Ga and In) have been synthesized by high frequency induction heating method. The compounds Eu 5 In 2 Sb 6 and Yb 5 X 2 Sb 6 crystallize respectively in the orthorhombic Ca 5 Ga 2 As 6 and Ba 5 Al 2 Bi 6 structure types, space group Pbam . The crystal structure of all the four compounds can be envisaged as a composition of infinite one dimensional [ X 2 Sb 6 ] 10− double chains arranged in parallel fashion along the [110] plane. The oxidation state of the rare earth atom has been deduced from the bond valence sum calculation on the structural data. The deduced values are found to corroborate well with the values that obtained from the magnetic susceptibility and the X-ray absorption near edge spectroscopy.

Pd2Ge nanoparticles were synthesized by superhydride reduction of K2PdCl4 and GeCl4. The syntheses were performed using a solvothermal method in the absence of surfactants, and the size of the nanoparticles was controlled by varying the reaction time. The powder X-ray diffraction (PXRD) and transmission electron microscopy data suggest that Pd2Ge nanoparticles were formed as an ordered intermetallic phase. In the crystal structure, Pd and Ge atoms occupy two different crystallographic positions with a vacancy in one of the Ge sites, which was proved by PXRD and energy-dispersive X-ray analysis. The catalyst is highly efficient for the electrochemical oxidation of ethanol and is stable up to the 250th cycle in alkaline medium. The electrochemical active surface area and current density values obtained, 1.41 cm2 and 4.1 mA cm–2, respectively, are superior to those of the commercial Pd on carbon. The experimentally observed data were interpreted in terms of the combined effect of adsorption energies of CH3CO...

A new compound Eu{sub 2}Pt{sub 3}Si{sub 5} with plate shaped morphology has been grown from excess In flux. The compound crystallizes in the orthorhombic U{sub 2}Co{sub 3}Si{sub 5} structure type, Ibam space group and the lattice parameters are a=10.007(2) A, b=11.666(2) A and c=6.0011(12) A. The crystal structure of this compound can be conceived as inter-twinned chains of [Pt{sub 2}Si{sub 2}] and [PtSi{sub 3}] tetrahedra connected along [100] direction to give rise to a complex three dimensional [Pt{sub 3}Si{sub 5}] network. Temperature dependent magnetic susceptibility data suggests that Eu{sub 2}Pt{sub 3}Si{sub 5} undergoes a strong antiferromagnetic ordering (T{sub N}=19 K) followed by a weak ferromagnetic transition (T{sub C}=5.5 K). The effective magnetic moment/Eu obtained from susceptibility data is 6.78 μ{sub B} accounts mixed valent Eu with almost 85% divalent Eu, which is supported by X-ray absorption near edge spectroscopy. The compound undergoes a metamagnetic transition under applied magnetic field through a probable spin flop mechanism. - Graphical abstract: Eu{sub 2}Pt{sub 3}Si{sub 5}, a new member in the U{sub 2}Co{sub 3}Si{sub 5} (Ibam) family undergoes metamagnetic transition at high magnetic field and Eu is in mixed valence state. - Highlights: • A new compound Eu{sub 2}Pt{sub 3}Si{sub 5} has been synthesizedmore » using indium as an inactive metal flux. • The compound undergoes metamagnetic transition at higher field. • Eu in this compound resides in a mixed valence state.« less

The compound EuAg4In8 has been obtained as single crystals in high yield from reactions run in liquid indium. X-ray diffraction on single crystals suggests that EuAg4In8 crystallizes in the CeMn4Al8 structure type, tetragonal space group I4/mmm with lattice constants a=b=9.7937(2) A and c=5.7492(2) A. Crystal structure of EuAg4In8 is composed of pseudo Frank–Kasper cages occupied by one europium atom in each ring, which are shared through the corner along the ab plane resulting in a three dimensional network. The magnetic susceptibility of EuAg4In8 was measured in the temperature range 2–300 K, which obeyed Curie–Weiss law above 50 K. Magnetic moment value calculated from the fitting indicates the presence of divalent europium, which was confirmed by X-ray absorption near edge spectroscopy. Electrical resistivity measurements suggest that EuAg4In8 is metallic in nature with a probable Fermi liquid behavior at low temperature.

Sm3Ni5Al19 was obtained as large rod shaped single crystals from reactive aluminium flux. Single crystal X-ray diffraction suggests that Sm3Ni5Al19 crystallizes in the Gd3Ni5Al19 structure type, orthorhombic space group Cmcm and lattice constants a = 4.0974(1) A, b = 16.0172(6) A and c = 27.0774(10) A. Sm3Ni5Al19 is a member of the Sm2n+mNi4n+mAl15n+4m series with n = 1 and m = 1. The crystal structure of Sm3Ni5Al19 consists of SmNiAl4 and Sm2Al4Al15 slabs intergrown along the b-axis. Magnetic susceptibility data on Sm3Ni5Al19 confirms the paramagnetic nature with a complicated magnetic ordering below 18 K. The inverse susceptibility data follows modified Curie-Weiss law above 150 K with effective magnetic moment 1.3 μ B/Sm atoms suggests trivalent Sm atoms.

The Yb 2 CuGe 6 and Yb 3 Cu 4 Ge 4 compounds were synthesized from reaction mixtures using indium as flux. Both powder and single crystal X-ray diffraction data were used to refine the crystal structures. Yb 2 CuGe 6 crystallizes in the monoclinic space group C 2/ m in the La 2 AlGe 6 type structure. The lattice parameters are a = 8.0011(16) A, b = 8.1962(16) A, c = 10.682(2) A and β = 100.63(3). The crystal structure of Yb 2 CuGe 6 can be described as the intergrowth of fragments Ge dimmers and zig–zag Ge chains. Yb 3 Cu 4 Ge 4 crystallizes in the orthorhombic space group Immm in the Gd 3 Cu 4 Ge 4 type structure. The lattice parameters are a = 4.1302(8) A, b = 6.5985(13) A and c = 13.691(3) A. X-ray absorption near edge spectroscopy (XANES) measurements indicate that Yb in Yb 2 CuGe 6 and Yb 3 Cu 4 Ge 4 exists as intermediate and trivalent states, respectively. The structural refinement of Yb 2 CuGe 6 is corroborated by total energy calculations within the local density approximation.

The compounds CeGa2 ,C e 0.82Mg0.50Ga1.68, Eu(Mg/Li)xGa2� x (0 6 x 6 0.4) and Eu(Mg/Li)xGa4� x (0 6 x 6 0.73) were synthesized and characterized by X-ray diffraction. CeGa2 and Ce0.82Mg0.50Ga1.68 crystallize in the AlB2 structure type with P6/mmm space group. The structure is composed of infinite arrays of planar hexagonal Ga atoms stacked along the [0 0 1] direction and the Ce atoms are sandwiched between them. Eu(Mg/Li)xGa2� x (0 6 x 6 0.4) crystallize in the KHg2 structure type with Imma space group and consists of the hexagonal rings of M (Li/Mg + Ga) atoms connected along the [1 0 0] plane forming a puckered network with voids occupied by two Eu atoms. The Eu(Mg/Li)xGa4� x (0 6 x 6 0.73) compounds crystallize in the BaAl4 structure type having I4/mmm space group. In Eu(Mg/Li)xGa4� x, the Eu atom occupies the edge and the body centered position of the unit cell while the Ga and M (Li/Mg + Ga) atoms forms a 3D polyanionic framework. Magnetic susceptibility of CeGa2, EuGa2, EuGa4 and their corresponding Li/Mg analogs are discussed.

The indium-rich intermetallic compound EuIrIn4 was synthesized using indium as the active metal flux. The crystal structure of EuIrIn4 was investigated by X-ray powder and single crystal diffraction. EuIrIn4 crystallizes in the YNiAl4 type, Cmcm space group, with lattice parameters, a = 4.5206(9) Å, b = 16.937(3) Å, c = 7.2661(15) Å. Europium atoms in EuIrIn4 are surrounded by three dimensional [IrIn4] polyanionic networks. EuIrIn4 shows two successive antiferromagnetic transitions at 5.4 and 10.8 K. Modified Curie-Weiss fitting on the magnetic susceptibility data within the temperature region 15-300 K gives the effective magnetic moment of 8.45μB/Eu. EuIrIn4 shows pronounced magnetic anisotropy perpendicular to the direction of the applied magnetic field.

Two new intermetallic compounds EuAuIn4 and EuAu2In4 having plate- and rodlike shapes, respectively, were synthesized using indium as an active metal flux. Both compounds crystallize in the orthorhombic system and can be classified as polyindide systems due to the presence of [In4] tetrameric units. EuAuIn4 adopts the YNiAl4 structure type with Cmcm space group and lattice parameters a = 4.6080(3) A, b = 17.0454(8) A, c = 7.5462(4). EuAu2In4 crystallizes in the NdRh2Sn4 structure type with Pnma space group and lattice parameters a = 18.5987(7) A, b = 4.6616(2) A, and c = 7.4669(3) A. EuAuIn4 consists of three-dimensional [AuIn4] units, and the europium atoms reside in the distorted hexagonal channels, whereas, in EuAu2In4, the europium atoms are enclosed by three-dimensional cages of [Au2In4] polyanionic units. Magnetic susceptibility measurements showed Curie–Weiss behavior within the temperature range of 80–300 K for EuAu2In4 and 10–300 K for EuAu2In4 with an effective magnetic moment (μeff) of 5.88 and...

Single crystals (SCs) of the compounds Eu3Ag2In9 and EuCu2Ge2 were synthesized through the reactions run in liquid indium. Eu3Ag2In9 crystallizes in the La3Al11 structure type [orthorhombic space group (SG) Immm] with the lattice parameters: a = 4.8370(1) A, b = 10.6078(3) A, and c = 13.9195(4) A. EuCu2Ge2 crystallizes in the tetragonal ThCr2Si2 structure type (SG I4/mmm) with the lattice parameters: a = b = 4.2218(1) A, and c = 10.3394(5) A. The crystal structure of Eu3Ag2In9 is comprised of edge-shared hexagonal rings consisting of indium. The one-dimensional chains of In6 rings are shared through the edges, which are further interconnected with other six-membered rings forming a three-dimensional (3D) stable crystal structure along the bc plane. The crystal structure of EuCu2Ge2 can be explained as the complex [CuGe](2+δ)– polyanionic network embedded with Eu ions. These polyanionic networks present in the crystal structure of EuCu2Ge2 are shared through the edges of the 011 plane containing Cu and Ge ...

The compounds Eu 5 In 2 Sb 6 and Yb 5 X 2 Sb 6 ( X = Al, Ga and In) have been synthesized by high frequency induction heating method. The compounds Eu 5 In 2 Sb 6 and Yb 5 X 2 Sb 6 crystallize respectively in the orthorhombic Ca 5 Ga 2 As 6 and Ba 5 Al 2 Bi 6 structure types, space group Pbam . The crystal structure of all the four compounds can be envisaged as a composition of infinite one dimensional [ X 2 Sb 6 ] 10− double chains arranged in parallel fashion along the [110] plane. The oxidation state of the rare earth atom has been deduced from the bond valence sum calculation on the structural data. The deduced values are found to corroborate well with the values that obtained from the magnetic susceptibility and the X-ray absorption near edge spectroscopy.

A new compound, Eu3Ir2In15, has been synthesized using indium as an active metal flux. The compound crystallizes in the tetragonal P4/mbm space group with lattice parameters a = 14.8580(4) Å, b = 14.8580(4) Å, and c = 4.3901(2) Å. It was further characterized by SEM-EDX studies. The effective magnetic moment (μeff) of this compound is 7.35 μB/Eu ion with a paramagnetic Curie temperature (θp) of -28 K, suggesting antiferromagnetic interaction. The mixed-valent nature of Eu observed in magnetic measurements was confirmed by XANES measurements. The compound undergoes demagnetization at a low magnetic field (10 Oe), which is quite unusual for Eu-based intermetallic compounds. Temperature-dependent resistivity studies reveal that the compound is metallic in nature. A comparative study was made between Eu3Ir2In15 and hypothetical vacancy-variant Eu5Ir4In10, which also crystallizes in the same crystal structure. However, our computational studies along with control experiments suggest that the latter is thermodynamically less feasible compared to the former, and hence we propose that it is highly unlikely that an RE5T4X10 would exist with X as a group 13 element.

We have synthesized the compounds RE2AgGe3 (RE =Ce, Pr, Nd) by arc melting. The crystal structure obtained from single crystal and powder X-ray diffraction suggests that these compounds crystallize in the α-ThSi2 structure type. The magnetic susceptibility data of Ce2AgGe3 follows Curie–Weiss (CW) law above 25 K without any magnetic ordering down to 2 K. The effective magnetic moment (μeff) was calculated as 2.53 μB/Ce and negative Curie paramagnetic temperature (θp)=−2.4 K hint weak antiferromagnetic coupling among the adjacent spins. Pr2AgGe3 shows a complex magnetic behavior wherein the magnetic susceptibility at field cooled and zero field cooled modes bifurcates at 11.5 K with the latter undergoing a cusp like maxima, probably due to weak ferromagnetic interaction. The θp and μeff obtained are 4 K and 4.33 μB/Pr, respectively. Nd2AgGe3 undergoes multiple magnetic transitions. Temperature dependent resistivity data reveals that three compounds are metallic in nature.

Single crystals of EuAg4In8 are obtained from a melt of Eu, Ag, and In (as the flux) in the molar ratio of 1:1.3:8.7 (alumina crucible in evacuated silica tubes, 1000 °C, 5 h; 850 °C, 2 d).

Single crystals of Yb2CuGe6 (I) and Yb3Cu4Ge4 (II) are prepared by melting of the elements in a Y/Cu/Ge molar ratio of 3:2:6 and 3:3:6, resp., in an indium flux (alumina crucible in evacuated silica tube, 850 °C, 2 d, slow cooling).

Two new intermetallic compounds Eu2AuSi3 and Yb2AuSi3 having prismatic and rod like shapes, respectively, were grown using indium as inert metal flux. The crystal structure of both compounds was refined using X-ray diffraction data on selected single crystals. Both compounds are ordered variants of the AlB2 structure type and crystallize in the orthorhombic system. Eu2AuSi3 adopts the Ca2AgSi3 structure type, Fmmm space group and lattice parameters a = 8.3060(17) A, b = 9.0369(18) A, c = 14.377(3) A. Yb2AuSi3, on the other hand, crystallizes in the Ba2LiSi3 structure type, Fddd space group and lattice parameters a = 8.2003(16) A, b = 14.187(3) A, c = 16.869(3) A. Both Eu2AuSi3 and Yb2AuSi3 consist of two dimensional hexagonal units built up of [Au3Si3] mixed sites and the europium atoms are sandwiched between two adjacent hexagonal layers. Magnetic measurements suggest both compounds have divalent rare earth atoms. The temperature dependent magnetic susceptibility data of Eu2AuSi3 suggests the Curie–Weiss behavior above 30 K and an antiferromagnetic ordering around 26 K. Yb2AuSi3 is diamagnetic in the higher temperature range (>175 K) and is weakly paramagnetic below 100 K indicating a probable valence fluctuation in Yb.