Space Group Ibam Research Articles

LiCuS, an intermediate phase in the electrochemical conversion reaction of CuS with Li: A potential environment-friendly battery and solar cell material

The crystal structure of a ternary sulfide with the approximate composition LiCuS, which is a promising candidate for environment-friendly battery and solar cell materials is reported. The crystal structure was solved by a combination of neutron and X-ray powder diffraction data, and 7Li solid-state NMR analysis. A yellow powder, Li1.1Cu0.9S, was obtained by the reaction of CuS with a slight excess of Li metal. The compound crystallizes in the Na3AgO2 structure type in the space group Ibam. An idealized crystal structure of Li1.1Cu0.9S can be derived from the cubic Li2S structure by moving a part of the Li along the c axis so that these Li atoms become linearly coordinated by S. All the metal sites are occupied by randomly mixed Li and Cu atoms; however, there is a strong preference for linear coordination by Cu. The density functional theory calculations show that Li1.1Cu0.9S is a direct band-gap semiconductor with an energy gap of 1.95 eV in agreement with experimental data.

Synthesis of Na2Mg3X2 (X = Sn, Pb) and Na4Mg4Sn3 and their crystal structures and thermoelectric properties

Novel ternary stannides and a plumbide, Na2Mg3X2 (X = Sn, Pb) and Na4Mg4Sn3, were synthesized by heating the corresponding elements. The crystal structures were determined by single-crystal X-ray diffraction analysis, and the electrical conductivities and Seebeck coefficients were measured. The crystal structures of Na2Mg3X2 [orthorhombic, a = 7.3066(9) Å, b = 14.4559(13) Å, c = 6.6433(7) Å for X = Sn, a = 7.4272(11), b = 14.770(3), c = 6.6852(11) Å for X = Pb] are based on the Mg5Ga2-type structure (space group Ibam, Z = 4). Na4Mg4Sn3 crystallizes in an orthorhombic cell [a = 6.879(3) Å, b = 7.154(2) Å, c = 22.285(7) Å, space group Fmmm, Z = 4] with layers of disordered Na atom arrangement with defects. The electrical conductivities measured for the polycrystalline sintered samples of Na2Mg3Sn2, Na4Mg4Sn3, and Na2Mg3Pb2 were 1.9 × 105 S m−1 at 300 K, 1.6 × 105 S m−1 at 307 K and 3.3 × 105 S m−1 at 300 K, respectively. The Seebeck coefficients (S) of Na2Mg3Sn2, Na4Mg4Sn3, and Na2Mg3Pb2 were +47 to +72, +29 to +67, and +10 to +24 µV K−1, respectively, and increased with increasing temperature of 300–600 K.

Stable structures of He andH2Oat high pressure

The knowledge of the structures that can exist in compounds containing helium is of interest for understanding the conditions where and if this inert element can form structures where closed shell electrons of helium can participate in bonding that is not describable exclusively by van der Waals interactions alone. In this study we examine stable mixtures of He and ${\mathrm{H}}_{2}\mathrm{O}$ at high pressures using a first-principles structure searching method. We find a thermodynamically stable structure that can be characterized by interactions comparable in strength to that of conventional hydrogen bonds. An orthorhombic structure with space group Ibam is identified that has progressively lower enthalpy with increasing pressure above 296 GPa than a mixture of He and ${\mathrm{H}}_{2}\mathrm{O}$. This mechanically and dynamically stable structure is found at pressures that are now becoming accessible to high-pressure techniques.

Mixed valence and metamagnetism in a metal flux grown compound Eu2Pt3Si5

A new compound Eu2Pt3Si5 with plate shaped morphology has been grown from excess In flux. The compound crystallizes in the orthorhombic U2Co3Si5 structure type, Ibam space group and the lattice parameters are a=10.007(2)Å, b=11.666(2)Å and c=6.0011(12)Å. The crystal structure of this compound can be conceived as inter-twinned chains of [Pt2Si2] and [PtSi3] tetrahedra connected along [100] direction to give rise to a complex three dimensional [Pt3Si5] network. Temperature dependent magnetic susceptibility data suggests that Eu2Pt3Si5 undergoes a strong antiferromagnetic ordering (TN=19K) followed by a weak ferromagnetic transition (TC=5.5K). The effective magnetic moment/Eu obtained from susceptibility data is 6.78μB 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.

Cs2Hg3S4: A Low-Dimensional Direct Bandgap Semiconductor

Cs2Hg3S4 was synthesized by slowly cooling a melted stoichiometric mixture of Hg and Cs2S4. Cs2Hg3S4 crystallizes in the Ibam spacegroup with a = 6.278(1) A, b = 11.601(2) A, and c = 14.431(3)A; dcalc = 6.29 g/cm3. Its crystal structure consists of straight chains of [Hg3S4]n2n– that engage in side-by-side weak bonding interactions forming layers and are charge balanced by Cs+ cations. The thermal stability of this compound was investigated with differential thermal analysis and temperature dependent in situ synchrotron powder diffraction. The thermal expansion coefficients of the a, b, and c axes were assessed at 1.56 × 10–5, 2.79 × 10–5, and 3.04 × 10–5 K–1, respectively. Large single-crystals up to ∼5 cm in length and ∼1 cm in diameter were grown using a vertical Bridgman method. Electrical conductivity and photoconductivity measurements on naturally cleaved crystals of Cs2Hg3S4 gave resistivity ρ of ≥108 Ω·cm and carrier mobility-lifetime (μτ) products of 4.2 × 10–4 and 5.82 × 10–5 cm2 V–1 for electro...

Synthesis, characterization and structure solution of ULS-1 |ETMA8(H2O)20|[Si24O48(OH)8], a layered silicate composed of half-sodalite cages

UOP layered silicate-1 (ULS-1), a highly siliceous layered silicate composed of [4262] half sodalite cages, has been synthesized hydrothermally at 100°C from solutions containing ethyltrimethylammonium hydroxide and silica or aluminosilicate sources and the structure solved from powder XRD data in the Ibam spacegroup with a=28.909Å, b=8.380Å, c=11.569Å at room temperature. TGA/MS and NMR, Raman and IR spectroscopic characterization were utilized to examine the properties of ULS-1 and provide information for structure solution. ULS-1 contains the same silicate layer structure and stacking as that found in RUB-15 and DLM-2, but with ethyltrimethylammonium (ETMA) cations in place of tetramethylammonium stabilizing the half sodalite cages. The presence of ETMA increases the interlayer spacing to ∼8.3Å from the previously observed 8Å, but also slightly increases the c unit cell constant in the layer direction.

Two types of adjacent dimer layers in the low-temperature phase of BaCuSi2O6

The low-temperature crystal structure of BaCuSi2O6has been investigated with high-resolution synchrotron x-ray and neutron powder diffraction techniques and has been found to be on average (ignoring the incommensurate modulation) orthorhombic, with the most probable space group Ibam. The Cu-Cu dimers in this material are forming two types of layers with distinctly different interatomic distances. Subtle changes also modify the partially frustrated interlayer Cu-Cu exchange paths. The present results corroborate the interpretation of low-temperature nuclear magnetic resonance and inelastic neutron scattering data in terms of distinct dimer layers. The experimentally determined low-temperature crystal structure of BaCuSi2O6is discussed in terms of its relation to the newer findings of theory and of the complementary experiments.

Synthesis and Crystal Structure of the Partially Oxidized Cyanoplatinates Rb1.75[Pt(CN)4]·1.25H2O and Cs1.75[Pt(CN)4]·0.5H2O

AbstractCrystal structures of partially oxidized cyanoplatinates were determined by single crystal analysis. Rb1.75[Pt(CN)4]·1.25H2O crystallizes monoclinic in the space group P21/c [a = 1171.4(2) pm, b = 3315.3(6) pm, c = 1054.4(2) pm, β = 114.253(2)°, V = 3733.2(11)·106 pm3, Z = 16, Ntotal = 31567, R(F)N = 0.0858]. The compound was obtained by mixing aqueous solutions of Rb2[Pt(CN)4]·1.5H2O and Rb2[Pt(CN)4]Br2. Cs1.75[Pt(CN)4]·0.5H2O crystallizes in the space group Ibam [a = 1266.1(3) pm, b = 1347.5(3) pm, c = 580.4(1) pm, V = 990.2(3)·106 pm3, Z = 4, Ntotal = 5997, R(F)N = 0.0807]. Crystals of the latter were grown by slow electrochemical oxidation of Cs2[Pt(CN)4]·H2O in aqueous solution using platinum wires as electrodes. In both compounds platinum is partially oxidized to Pt+2.25 and the nearly square‐planar tetracyanoplatinate groups are arranged to columns in a staggered conformation. The rubidium compound features a large unit cell with nonlinear chains of platinum atoms and short alternating Pt–Pt distances of 292 and 294 pm, the cesium compound crystallizes more symmetrically with Pt–Pt distances of c/2 = 290 pm. The two compounds were also characterized by differential thermal analysis, thermogravimetry, infrared, and Raman spectroscopy.

A10LaCdSb9 (A=Ca, Yb): A Highly Complex Zintl System and the Thermoelectric Properties

Two new Zintl compounds A(10)LaCdSb(9) (A=Ca, Yb), namely, Ca(9.81(1))La(0.97(1))Cd(1.23(1))Sb(9) and Yb(9.78(1))La(0.97(1))Cd(1.24(1))Sb(9), have been designed and synthesized by applying the Zintl concept. Although both compounds are isoelectronic with their Ca(11)InSb(9) and Yb(11)InSb(9) analogues, they crystallize in a new structure type with the orthorhombic space group Ibam (No.72) and feature very complex anion structures, which are composed of unique [Cd(2)Sb(6)](12-) clusters, dumbbell-shaped [Sb(2)](4-) dimers, and isolated [Sb](3-) anions. For Yb(9.78(1))La(0.97(1))Cd(1.24(1))Sb(9), an extremely low lattice thermal conductivity of 0.29 W m(-1) K(-1) was observed at 875 K, which almost approaches the lowest reported limit of nonglassy or nonionically conducting bulk materials. According to thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses, both compounds show very good thermal stability and no melting or phase transition processes were found below 1173 K. Although related thermoelectric property studies on Yb(9.78(1))La(0.97(1))Cd(1.24(1))Sb(9) only present a maximum ZT of 0.11 at 920 K, owing to its low Seebeck coefficients, these materials are still very promising for their high temperature stability and low thermal conductivity. Furthermore, as mixed cations exist with different charges, it makes this system very flexible in tuning the related electrical properties.

Magnetic and transport properties of Pr2Pt3Si5

We have investigated the magnetic and transport properties of a polycrystalline Pr2Pt3Si5 sample through the dc and ac magnetic susceptibilities, electrical resistivity, and specific heat measurements. The Rietveld refinement of the powder X-ray diffraction data reveals that Pr2Pt3Si5 crystallizes in the U2Co3Si5-type orthorhombic structure (space group Ibam). Both the dc and ac magnetic susceptibility data measured at low fields exhibit sharp anomaly near 15K. In contrast, the specific heat data exhibit only a broad anomaly implying no long range magnetic order down to 2K. The broad Schottky-type anomaly in low temperature specific heat data is interpreted in terms of crystal electric field (CEF) effect, and a CEF-split singlet ground state is inferred. The absence of the long range order is attributed to the presence of nonmagnetic singlet ground state of the Pr3+ ion. The electrical resistivity data exhibit metallic behavior and are well described by the Bloch–Grüniesen–Mott relation.

Syntheses and Structures of Sc2Nb4–xSn5, YNb6Sn6, and ErNb6Sn5: Exploratory Studies in Ternary Rare-Earth Niobium Stannides

Three new rare-earth (RE) niobium stannides, namely, Sc(2)Nb(4-x)Sn(5) (x = 0.37, 0.52), YNb(6)Sn(6), and ErNb(6)Sn(5), have been obtained by reacting the mixture of corresponding pure elements at high temperature and structurally characterized by single-crystal X-ray diffraction studies. Sc(2)Nb(4-x)Sn(5) crystallizes in the orthorhombic space group Ibam (No. 72) and belongs to the V(6)Si(5) type. Its structure features a three-dimensional (3D) network composed of two-dimensionally (2D) corrugated [Nb(2)Sn(2)] and [Nb(2)Sn(3)] layers interconnected via Nb-Sn bonds, forming one type of one-dimensional (1D) narrow tunnels along the c axis occupied by Sc atoms. YNb(6)Sn(6) crystallizes in the hexagonal space group P6/mmm (No. 191) and adopts the HfFe(6)Ge(6) type, and ErNb(6)Sn(5) crystallizes in the trigonal space group R3m (No. 166) and belongs to the LiFe(6)Ge(5) type. Their structures both feature 3D networks based on 2D [Nb(3)Sn], [Sn(2)], and [RESn(2)] layers (RE = Y, Er). In YNb(6)Sn(6), one type of [Nb(3)Sn] layer is interconnected by [Sn(2)] and [YSn(2)] layers via Nb-Sn bonds to form a 3D network. However, in ErNb(6)Sn(5), two types of [Nb(3)Sn] layers are interlinked by [Sn(2)] and [ErSn(2)] layers via Nb-Sn bonds into a 3D framework. Electronic structure calculations and magnetic property measurements for "Sc(2)Nb(4)Sn(5)" and YNb(6)Sn(6) indicate that both compounds show semimetallic and temperature-independent diamagnetic behavior.

Syntheses and Crystal Structures of the Solid Solution Sr4OBr2.89(2)Cl3.11(2) and the Elusive Ba2OBr2

Transparent and colorless single crystals of the compounds Sr4OBr2.89(2)Cl3.11(2) and Ba2OBr2 were obtained by solid-state reactions of SrCl2, SrBr2 and SrO (3 : 3 : 2 molar ratio) or by using an excess of BaO together with BaBr2 and Ba as a flux with the molar ratio 3 : 2 : 2, respectively. Ba2OBr2 crystals are isopointal to K2ZnO2 adopting the orthorhombic space group Ibam (no. 72, Z = 4) with the cell parameters a = 7247.44(10), b = 1297.76(20) and c = 657.43(10) pm. Sr4OBr2.89(2)Cl3.11(2) is isotypic to Ba4OCl6 (or isopointal to K6ZnO4) and crystallizes in the hexagonal space group P63mc (no. 186, Z = 2) with the cell parameters a = 982.20(4) and c = 750.41(7) pm.

Uniform Patterns of Fe-Vacancy Ordering in the Kx(Fe,Co)2–ySe2 Superconductors

The Fe-vacancy ordering patterns in the superconducting KxFe2-ySe2 and non-superconducting Kx(Fe,Co)2-ySe2 samples have been investigated by electron diffraction and high angle annular dark field scanning transmission electron microscopy. The Fe-vacancy ordering occurs in the ab plane of the parent ThCr2Si2-type structure, demonstrating two types of patterns. The superstructure I retains the tetragonal symmetry and can be described with the aI = bI = as{\surd}5 (as is the unit cell parameter of the parent ThCr2Si2-type structure) supercell and I4/m space group. The superstructure II reduces the symmetry to orthorhombic with the aII = as{\surd}2, bII = 2as{\surd}2 supercell and the Ibam space group. This type of superstructure is observed for the first time in KxFe2-ySe2. The Fe-vacancy ordering is inhomogeneous: the disordered areas interleave with the superstructures I and II in the same crystallite. The observed superstructures represent the compositionally-dependent uniform ordering patterns of two species (the Fe atoms and vacancies) on a square lattice. More complex uniform ordered configurations, including compositional stripes, can be predicted for different chemical compositions of the KxFe2-ySe2 (0 < y < 0.5) solid solutions.

Magnetic ordering and crystal field effects in theR2Ir3Sn5(R=La–Nd, Gd–Tm) system

We report on the detailed magnetic properties of polycrystalline ternary rare-earth intermetallic stannide compounds $R$${}_{2}$Ir${}_{3}$Sn${}_{5}$ ($R$ $=$ La--Nd, Gd--Tm). Except for La${}_{2}$Ir${}_{3}$Sn${}_{5}$, all the other compounds of $R$${}_{2}$Ir${}_{3}$Sn${}_{5}$ ($R$ $=$ Ce--Nd, Gd--Tm) crystallize in the orthorhombic Y${}_{2}$Rh${}_{3}$Sn${}_{5}$(Cmc2${}_{1}$) type structure. La${}_{2}$Ir${}_{3}$Sn${}_{5}$ crystallizes in the U${}_{2}$Co${}_{3}$Si${}_{5}$ type orthorhombic crystal structure with the space group Ibam. Transport and magnetization measurements were done from 1.8 to 300 K and the heat-capacity measurement was done from 2 to 30 K. We found from the magnetic measurements that Ce${}_{2}$Ir${}_{3}$Sn${}_{5}$ is a Kondo system, which undergoes an antiferromagnetic ordering at 2.9 K, while no magnetic ordering was observed in Pr${}_{2}$Ir${}_{3}$Sn${}_{5}$ and Nd${}_{2}$Ir${}_{3}$Sn${}_{5}$ down to 1.8 K. The higher rare earths from Gd--Tm of this series exhibit magnetic ordering below 10 K. Crystal field analysis was done on both the magnetic susceptibility and heat capacity to find the crystal field level schemes. From the detailed magnetic measurements, we found that the magnetic ordering temperature deviates from the expected de Gennes scaling, which indicates that the RKKY interaction needs to be modified, including the crystal field effects, to account for this deviation.

Synthesis, Characterization and Crystal Structure of a New One-Dimensional Heterobimetallic Coordination Polymer Based on [(Tp)Fe(CN)3

By using a pre-designed anionic precursor [TpFeIII(CN)3]− (Tp = hydrotris(pyrazolyl)borate) as a structural building block, a new cyanide-bridged one-dimensional heterobimetallic coordination polymer, [(Tp)2Fe 2 III (CN)6Zn·2H2O] n (I) has been prepared and characterized by X-ray single crystal diffraction, Mossbauer and magnetic experiments. Complex I crystallizes in the orthorhombic Ibam space group with a = 14.4094(8) A, b = 18.3003(10) A, c = 12.9855(7) A and consists of rhombic chains, in which the [TpFeIII(CN)3]− unit acts as a bridging bidentate ligand toward two Zn2+ atoms through two of its three cyanide groups. [(Tp)2Fe 2 III (CN)6Zn·2H2O] n (I) crystallizes in the orthorhombic Ibam space group and consists of rhombic chains, in which the [TpFeIII(CN)3]− unit acts as a bridging bidentate ligand toward two Zn2+ atoms through two of its three cyanide groups.

Isolated ∞1[ZnPn2]4− Chains in the Zintl Phases Ba2ZnPn2 (Pn = As, Sb, Bi)—Synthesis, Structure, and Bonding

Reported are the synthesis of three new Zintl phases, Ba2ZnAs2 (I), Ba2ZnSb2 (II), Ba2ZnBi2 (III) and their structural characterization by single-crystal X-ray diffraction. They are isoelectronic and isotypic and crystallize in the orthorhombic space group Ibam, with four formula units per cell (Pearson symbol oI20; K2SiP2 type). Lattice parameters are as follows: a = 13.399(9)/14.133(3)/14.325(6); b = 6.878(5)/7.1919(15)/7.280(3); and c = 6.541(4)/6.9597(15)/7.089(3) A for I/II/III, respectively. The structure can be viewed as polyanionic chains, infinity1[ZnPn2]4- (Pn = As, Sb, Bi), running parallel to the c-axis, with Ba2+ cations separating them. The chains are made of edge-shared ZnPn4 tetrahedra, which are isosteric with the infinity1[SiS4/2] chains in SiS2. This and some other structural parallels with known Zintl phases have been discussed. The experimental results have been complemented by tight-binding linear muffin-tin orbital electronic structure calculations.

Synthesis, structure, and properties of a new 3D hydrogen-bonded porous coordination polymer

A new coordination polymer, [Cd(HMal)(Bipy)(H2O) · 2H2O (I) (H3Mal is malic acid, Bipy is 4,4′-bipyridine), has been synthesized from H3Mal and Bipy under hydrothermal conditions and characterized by elemental analysis, IR, TG, and single-crystal X-ray diffraction. The X-ray diffraction analysis reveals that I (C14H16N2O7Cd) crystallizes in the orthorhombic system, space group Ibam. The adjacent cadmium(II) atoms were first interconnected by the HMal ligands via carboxylate oxygen atoms and its adjacent hydroxyl group to generate an infinite zigzag [Cd(HMal)]n chain, which are further linked by Bipy ligands to form a 2D wavelike layer. Interestingly, the adjacent layers are further connected via hydrogen bonds, giving rise to a 3D porous framework with a cross-sectional area of 11.690 × 9.326 A2. The unit cell parameters for I: a = 8,457(1), b = 22.030(7), c = 23.066(7) V = 4297(2) A3, Z = 4.

Theoretical investigation of the vibrational properties ofBeH2andLi2BeH4

First-principles calculations of BeH2 and Li2BeH4 were performed and compared to inelastic neutron scattering. The crystal structure (P21/c space group) of Li2BeH4 contains BeH4 tetrahedral units similar to those in alpha-BeH2 (Ibam space group), but separated from each other by Li atoms. Calculated vibrational density of states revealed the origin of the observed major vibrational modes. Charge density maps and electronic density of states indicate interplay between covalent and ionic bonding in Li2BeH4 and provide a better understanding of the nature of the bonding in these materials.

Chains of trans-edge connected [ZM 4] tetrahedra (Z = N and O) in the lanthanide nitride chlorides M 2NCl 3 and Na 2M 4ONCl 9 (M = La–Nd)

Single crystals of La 2NCl 3 and Na 2Nd 4ONCl 9 were prepared from LaCl 3, La and NaN 3 or NdCl 3, NdOCl, Nd and NaN 3 (both at 850 °C for 7 d) in silica ampoules by a flux method with NaCl as flux and for the second compound also as sodium source. La 2NCl 3 crystallizes in the orthorhombic system with space group Ibam (no. 72) and four formula units in a unit cell of the dimensions a = 1375.32(9), b = 691.89(5) and c = 618.23(4) pm, while Na 2Nd 4ONCl 9 crystallizes in space group P2 1/ m (no. 11) of the monoclinic system with two formula units in a unit cell of the dimensions a = 803.54(6), b = 1134.26(8), c = 928.31(7) pm and β = 107.109(5)°. In both structures the dominating features are trans-edge connected [ZM 4] tetrahedra in { [ Z M 4 / 2 e ] x + } ∞ 1 chains (M 2NCl 3: M = La, Z = N, x = 3.0; Na 2M 4ONCl 9: M = Nd, Z = (1/2)O + (1/2)N, x = 3.5; superscript e: edge connected). These straight chains run parallel to [0 0 1] in La 2NCl 3 and are connected via trans-edge sharing [(Cl1)La 4] 11+ tetrahedra in the same way as the [NLa 4] 9+ tetrahedra themselves. The second sort of chloride (Cl2) interconnects the layers of the two different types of chains. As a consequence of the lanthanide contraction the nitride chlorides with the composition M 2NCl 3 (M = La–Nd, Gd) crystallize in two different orthorhombic space groups. La 2NCl 3 is structurally isotypic with Ce 2NCl 3 and Pr 2NCl 3 (space group: Ibam), while Nd 2NCl 3 and Gd 2NCl 3 crystallize similarly, but in space group Pbcn. In Na 2Nd 4ONCl 9 the connection between the zigzag chains of trans-edge shared [ZNd 4] 9.5+ tetrahedra (Z = O and N in a 1:1 molar ratio) appears to be more difficult. They are directly coupled via chloride anions and via Cl −–Na +–Cl − bridges (CN(Na +) = 6) in a three-dimensional framework, so the structure is the same as for Na 2Gd 4ONCl 9. Different influences shape the layout of the individual chains as described in the following paper.

Valence fluctuation in Ce 2Co 3Ge 5 and crystal field effect in Pr 2Co 3Ge 5

Polycrystalline samples of ternary rare-earth germanides R 2Co 3Ge 5 (R=La, Ce and Pr) have been prepared and investigated by means of magnetic susceptibility, isothermal magnetization, electrical resistivity and specific heat measurements. All these compounds crystallize in orthorhombic U 2Co 3Si 5 structure (space group Ibam). No evidence of magnetic or superconducting transition is observed in any of these compounds down to 2 K. The unit cell volume of Ce 2Co 3Ge 5 deviates from the expected lanthanide contraction, indicating non trivalent state of Ce ions in this compound. The reduced value of effective moment ( μ eff ≈0.95 μ B ) compared to that expected for trivalent Ce ions further supports valence-fluctuating nature of Ce in Ce 2Co 3Ge 5. The observed temperature dependence of magnetic susceptibility is consistent with the ionic interconfiguration fluctuation (ICF) model. Although no sharp anomaly due to a phase transition is seen, a broad Schottky-type anomaly is observed in the magnetic part of specific heat of Pr 2Co 3Ge 5. An analysis of C mag data suggests a singlet ground state in Pr 2Co 3Ge 5 separated from the singlet first excited state by 22 K and a doublet second excited state at 73 K.