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Eight new compounds with a general formula Ca14–xRExMnSb11 (RE = La–Nd, Sm, Gd–Dy; x ≈ 1) were synthesized by the molten flux method and their structures were established via single-crystal X-ray diffraction. The overarching goal of this study was to investigate the effect of electron doping, via substitution of RE3+ at Ca2+ sites, on the crystal structure and physical properties of Ca14MnSb11, which is a candidate for thermoelectric applications. All studied phases are isostructural, and crystallize in the tetragonal body-centered space group I41/acd (Ca14AlSb11 structure type, Pearson index tI208). The structure is made up of MnSb410– tetrahedra, randomly mixed Ca2+ and RE3+ cations, Sb3– anions, and linear Sb37– polyanions. Comprehensive structural work confirms high rare-earth metal content with Ca2+/RE3+ randomly mixed on all four cation sites, with the caveat that the larger RE atoms (La–Nd) prefer to occupy the Ca2 site, while the smaller RE atoms (Sm, Gd, Tb, and Dy) preferably occupy the Ca1 site. Nearly phase-pure polycrystalline samples have been synthesized using solid-state reactions, and have been used for physical property measurements. The resistivities of the bulk Ca14–xRExMnSb11 (RE = La–Nd, Sm, Gd; x ≈ 1) samples reveal semiconducting behavior, consistent with the notion of electron doping in the parent p-type Ca14MnSb11 material. Magnetic susceptibilities suggest complex magnetic ordering at temperatures below ca. 50 K, likely originating from coupling between two or more magnetic sub-lattices.

Eight new compounds with a general formula Ca14–xRExMnSb11 (RE = La–Nd, Sm, Gd–Dy; x ≈ 1) were synthesized by the molten flux method and their structures were established via single-crystal X-ray diffraction. The overarching goal of this study was to investigate the effect of electron doping, via substitution of RE3+ at Ca2+ sites, on the crystal structure and physical properties of Ca14MnSb11, which is a candidate for thermoelectric applications. All studied phases are isostructural, and crystallize in the tetragonal body-centered space group I41/acd (Ca14AlSb11 structure type, Pearson index tI208). The structure is made up of MnSb410– tetrahedra, randomly mixed Ca2+ and RE3+ cations, Sb3– anions, and linear Sb37– polyanions. Comprehensive structural work confirms high rare-earth metal content with Ca2+/RE3+ randomly mixed on all four cation sites, with the caveat that the larger RE atoms (La–Nd) prefer to occupy the Ca2 site, while the smaller RE atoms (Sm, Gd, Tb, and Dy) preferably occupy the Ca1 site. Nearly phase-pure polycrystalline samples have been synthesized using solid-state reactions, and have been used for physical property measurements. The resistivities of the bulk Ca14–xRExMnSb11 (RE = La–Nd, Sm, Gd; x ≈ 1) samples reveal semiconducting behavior, consistent with the notion of electron doping in the parent p-type Ca14MnSb11 material. Magnetic susceptibilities suggest complex magnetic ordering at temperatures below ca. 50 K, likely originating from coupling between two or more magnetic sub-lattices.

Crystals of Ba7Al4Sb9 (I), Ba7Ga4P9 (II), and Ba7Ga4As9 (III) are prepared by melting the respective elements in molten Al or Pb fluxes (evacuated silica tubes, 960 °C, 20 h (Al flux) or 40 h (Pb flux)).

The four ternary arsenides ATt3As3 (A=K, Rb; Tt=Ge, Sn) were obtained by reaction of the elements at 600–650 °C. They adopt an orthorhombic structure (space group Pnma, Z=4, with cell parameters ranging from a=9.9931(11) A, b=3.7664(4) A, c=18.607(2) A for KGe3As3 to a=10.3211(11) A, b=4.0917(4) A, c=19.570(2) A for RbSn3As3) containing corrugated [Tt3As3] layers built from Tt-centred trigonal pyramids and tetrahedra forming five-membered rings decorated with As handles. They can be considered to be Zintl phases with Tt atoms in +4, +3, and +1 oxidation states. Band structure calculations predict that these compounds are semiconductors with narrow band gaps (0.71 eV in KGe3As3, 0.50 eV in KSn3As3).

The quaternary germanide arsenides ZrCuGeAs and HfCuGeAs were prepared by reaction of “ZrCuGe” or “HfCuGe” precursor materials with As at 800 °C. They are new representatives of the ZrCuSiAs-type structure (tetragonal, space group P4/nmm, Z = 2, Pearson symbol tP8), as determined by single-crystal X-ray diffraction on ZrCuGeAs (a = 3.7155(2) A, c = 9.5644(6) A) and powder X-ray diffraction on HfCuGeAs (a = 3.6935(3) A, c = 9.5557(9) A). They belong in the small category of ZrCuSiAs-type compounds exhibiting strong covalent bonding in three dimensions, as reflected in their location in a structure map and as confirmed by band structure calculations. X-ray photoelectron spectroscopy provides evidence for anionic As atoms. Both compounds exhibit temperature-independent Pauli paramagnetism.

Ternary rare-earth cobalt gallides RE4Co3Ga16 (RE = Gd–Er, Y) have been prepared by arc-melting of the elements followed by annealing at 800 °C. Single crystals of the Gd and Tb members were also grown in the presence of a Ga self-flux. They extend the rare-earth substitution possible in the Sm4Co3Ga16-type structure (Pearson symbol tP23, space group P4/mmm, Z = 1), in which additional Co atoms enter as self-interstitials into the parent RE2CoGa8 structure. Structural refinements were carried out on single-crystal (RE = Gd, Tb) and powder (RE = Dy, Ho, Er, Y) X-ray diffraction data. Cell parameters lie in the ranges of a = 6.03–5.96 A and c = 11.11–10.96 A. Magnetic measurements on RE4Co3Ga16 (RE = Gd, Tb, Dy) reveal that they order antiferromagnetically below TN of 19, 25, and 14 K, respectively; Y4Co3Ga16 is Pauli paramagnetic. The electrical resistivity of Tb4Co3Ga16 undergoes a transition coincident with the magnetic ordering temperature. Band structure calculations on Y4Co3Ga16 indicate that the major bonding contributions arise from Co–Ga and Ga–Ga interactions, with the stuffing of interstitial Co atoms into octahedral sites of the parent Y2CoGa8 structure, which provides additional Co–Ga bonding stabilization.

The series of quaternary sulfides with general formula Ln2CuMS5 (Ln=La, Ce; M=Sb, Bi) have been synthesized by solid-state reactions. Three representative members have been structurally characterized by single-crystal X-ray diffraction. La2CuSbS5 crystallizes in a new structure type (space group Ima2 (no. 46), Z=4, a=13.401(2) A, b=7.592(1) A, c=7.598(1) A, V=773.1(3) A3). The bismuth analogs of composition La2CuBiS5 and Ce2CuBiS5 crystallize with the La2CuInSe5 structure type (space group Pnma (no. 62), Z=4). Lattice parameters for La2CuBiS5: a=11.9213(5) A, b=3.9967(2) A, c=17.0537(8) A, V=812.56(7) A3; lattice parameters for Ce2CuBiS5: a=11.9179(15) A, b=3.9596(5) A, c=16.955(2) A, V=800.13(17) A3). The similarities and the differences between the two structures are discussed. Electronic structure calculations for La2CuSbS5 and La2CuBiS5 are also presented; they suggest semiconducting behavior with energy gaps exceeding 1.7 eV.

Arc-melting and annealing of the elements (evacuated silica tubes, 800 °C, 1 week) is used to prepare ≈50 new quaternary germanides of the series Ln4M2InGe4 (Ln: Ce—Lu except Eu and Yb; M: Fe, Co, Ni, Ru, Rh, Ir) and a different but closely related series Ln4RhInGe4.

Single crystals of the new title Zintl phases are prepared by solid state reactions from mixtures of the elements in the molar ratio of Na:Ca:M:Sb = 3:3:1:4 (M: Al, Ga, In) in sealed Nb containers (1173 K, 24 h).

The title compounds are prepared from the elements (800 °C, 10 d) and characterized by powder and single crystal XRD, electrical resistivity measurements, and TB-LMTO-ASA band structure calculations.

KCdGeAs2 (I) and RbCdGeAs2 (II) are prepared by solid state reactions of stoichiometric mixtures of the elements (alumina crucible in evacuated silica tube, 650 °C (I) and 600 °C (II), 10 d).

The title compounds are prepared by arc melting of stoichiometric amounts of the elements followed by annealing (evacuated quartz tubes, 770 K, 720 h).

Three series of quaternary pnictides, LnCuZnAs2 (Ln: Y, La—Nd, Sm, Gd—Lu), LnAgZnP2 (Ln: La—Nd, Sm, Gd—Dy), and LnAgZnAs2 (Ln: La—Nd, Sm, Gd—Dy) are prepared by solid reaction of the elements (evacuated silica tubes, 1.

The new title compounds (RE: Y, La—Er) are prepared from stoichiometric mixtures of the elements at 1050 °C (14 d) for the sulfides and at 900 °C (5 d) for the selenides, respectively.

The title compounds are prepared from stoichiometric mixtures of the elements (silica tubes, 1050 °C, 96 h) and characterized by powder and single crystal XRD, XPS, magnetic susceptibility measurements, and TB-LMTO-ASA band structure calculations.

The title compounds are synthesized from stoichiometric mixtures of the elements (alumina crucibles, 600 °C, 10 d) and characterized by single crystal XRD and TB-LMTO-ASA band structure calculations.

Ln4Mn2InGe4 (Ln: La Nd, Sm, Gd—Tm, Lu) are prepared by arc melting of stoichiometric mixtures the elements and annealing at 800 °C (evacuated silica tubes, 12 d).

Rb2Cd5As4 (I), Rb2Zn5Sb4 (II) and the solid solution Rb2Cd5(As,Sb)4 (III) are prepared by melting of the elements (Nb tubes in evacuated silica ampule; (I): 923 K, 7 d, ice quenching, (II): 823 K, 10 d, cooling rate 3 K/h).

Ten quaternary arsenides of title are prepared by reaction of stoichiometric mixtures of the elements (alumina crucible, 600—650 °C, 10 d).

The ternary rare-earth zinc arsenides RE Zn 2 As 3 ( RE =La–Pr) have been prepared by reactions of the elements at 800 °C. They adopt new tetragonal structure types, with the La member (space group I 4/ mmm , Z =4, a =4.1133(2) A, c =32.1246(14) A) differing from the Ce and Pr members (space group P 4/ nmm , Z =2, a =4.0804(6)–4.0534(12) A, c =16.089(5)–16.059(10) A, respectively) in the disposition of RE -centred square antiprisms on opposite sides of square As nets. The structures contain thick anionic slabs, built from edge-sharing ZnAs 4 tetrahedra, that can be considered either as stackings of three PbO-type layers or as fragments of the fluorite-type structure. These slabs are deficient in Zn and are reminiscent of the same features in binary arsenide Zn 3 As 2 . LaZn 2 As 3 exhibits temperature-independent paramagnetism whereas CeZn 2 As 3 follows modified Curie–Weiss behavior consistent with Ce 3+ species but with no occurrence of long-range ordering.

Two new ternary phases, (Mo1-xFex)2P (x = 0.30—0.82) and (Mo1-xFex)3P (x = 0.10—0.15) exist in the isothermal section of the title system at 800 °C.

The pnictides Ln2Mn3Cu9P7 (Ln: La—Nd, Sm, Gd—Dy) and Ln2Mn3Cu9As7 (Ln: La—Nd) are prepared from stoichiometric mixtures of the elements (800 °C, 14 d).

The new title compounds are prepared from the elements with excess Ga acting as a self-flux (1000 °C, 7 h).

The title compound is synthesized by reaction of a stoichiometric mixture of the elements (alumina crucible, 850 °C for 2 d and 800 °C for 7 d).

The title compounds are prepared from stoichiometric mixtures of the elements (alumina crucible, 650 °C for K sample, 600 °C for Rb sample, 10 d) and characterized by single crystal XRD and TB-LMTO-ASA band structure calculations.

The new title compounds are prepared by reactions of stoichiometric mixtures of the elements (alumina crucible, 850 °C, 1—4 d) and characterized by single crystal XRD.

The title compounds are prepared from stoichiometric mixtures of the elements (800 °C, 7 d) and characterized by single crystal XRD, electrical resistivity measurements, and TB-LMTO-ASA band structure calculations.

The title compounds are prepared by reaction of “ZrCuGe” or “HfCuGe” precursors (obtained by arc melting of the elements) with As at 800 °C for two weeks.

The compounds LnZn3As3 (Ln: La—Nd, Sm) with polymorphic modifications different from the previously known forms and the corresponding compounds LnCd3As3 (Ln: La—Pr) are prepared from the elements (800 °C, 7 d) and characterized by powder and single crystal XRD, electrical resistivity and magnetic measurements, and TB-LMTO computations.

The title compounds are prepared from the elements (800 °C, 336 h) and characterized by powder and single crystal XRD, magnetic susceptibility and electrical resistivity measurements, and TB-LMTO band structure calculations.

The title compounds are prepared by arc-melting the elements followed by annealing at 800 °C for three weeks.

The title compounds are prepared from stoichiometric mixtures of the elements (900 °C, 7 d) and characterized by powder XRD, XPS, magnetic measurements, and TB-LMTO band structure calculations.

The rare-earth iron arsenides RE 12 Fe 57.5 As 41 (RE = La, Ce) have been prepared by direct reactions of the elements in the presence of a Sn flux. Analysis of single-crystal X-ray diffraction data reveals that they adopt a new orthorhombic structure type (Pearson symbol oP236, space group Pmmn, Z = 2; a = 10.8881(9) A, b = 25.753(2) A, c = 12.5436(10) A for RE = La; a = 10.8376(8) A, b = 25.639(2) A, c = 12.4701(9) A for RE = Ce). In this metal-rich arsenide, the complex three-dimensional network (derived from 4 RE, 24 Fe, and 17 As sites) can be described as being built from unusual wavelike layers of connected As-centered trigonal prisms. Five of the Fe sites are partially occupied. The electronic structure of these compounds was probed through core-line X-ray photoelectron spectra. Magnetic susceptibility measurements indicated ferromagnetic ordering at T c = 125 and 95 K for the La and Ce compounds, respectively. Electrical resistivity measurements on single crystals of Ce 12 Fe 57.5 As 41 showed metallic behavior with a prominent transition that coincides closely with the ferromagnetic ordering temperature.

A new ternary phosphide Y 6 Ni 15− x P 10+ y ( x =0.08, y =0.18) has been obtained in the Y–Ni–P system. Single crystals of this compound have been investigated on a Nonius KappaCCD X-ray diffractometer using Mo Kα radiation ( λ =0.071073 nm). The symmetry has been found to be hexagonal with space group P 6 3 / m and unit cell parameters a =1.6447(1) nm and c =0.37891(2) nm. Structure refinement including anisotropic displacement parameters led to the following results: R F =0.056 ( R w =0.047), GOF=1.060 for 558 reflections with F ( h k l ) > 4 σF ( h k l ). The ternary phosphide Y 6 Ni 15− x P 10+ y exhibits a new structure, which is derived from the Ce 6 Ni 15 P 10 and Nd 3 Ni 7 P 5 structure types.