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By crystallization from strongly acidic aqueous solutions, nickel and zinc tetrahydrogen-decaoxodiperiodate hexahydrate, NiH4I2O10·6H2O and ZnH4I2O10·6H2O, have been obtained and found to be isotypic to CuH4I2O10·6H2O (P21/c, no. 14) with the lattice parameters a = 1070.3, b = 544.0, c = 1187.2 pm, β = 112.6° for the Ni compound and a = 1073.3, b = 545.3, c = 1189.5 pm and β = 112.5° for the Zn compound. The crystal structure of MgH4I2O10·6H2O has been reinvestigated and contrary to former results found to be isotypic to the Cu compound as well. IR and Raman spectra are given and analyzed with respect to the internal vibrations of the H4I2O10 2− ion and the hydrogen bonding system. According to high-temperature Raman spectra and DTA and TG measurements, the compounds decompose in the temperature range up to 300 °C via unknown salts with the anions H4IO6 2− and IO4 − to the corresponding iodates. In the case of the Ni compound the exothermic decomposition to the iodate occurs in two steps.

By solid state reaction of the binary sulfides, a new compound, Mn0.86In0.12Ga2S4, has been synthesized and its crystal structure determined. The compound crystallizes in the space group C2/m (no. 12) with a = 1232.6(2), b = 2636.9(5), c = 642.4(1) pm, β = 100.66(3)°, Z = 14. In the structure empty channels with a cross section of 320× 1082 pm2 running parallel to [001] are present.

The compounds (NH4)3[Ta(O2)4], K3[Ta(O2)4], Rb3[Ta(O2)4] and Cs3[Ta(O2)4] have been prepared and investigated by X-ray powder methods as well as Raman- and IR-spectroscopy. In the case of Rb3[Ta(O2)4] the structure has been solved from single crystal data. It is shown that all these compounds are isotypic and crystallize in the K3[Cr(O2)4] type (SG I 4 2m , No. 121). The infrared- and Raman spectra (recorded on powdered samples) are discussed with respect to the internal vibrations of the peroxo-group and the dodecahedral [Ta(O2)4]3− ion. Symmetry coordinates for the [Ta(O2)4]3− ion are given from which the vibrational modes of the O–O stretching vibrations of the O22− groups, the Ta–O stretching vibrations and the Ta–O bending vibrations are deduced.

By crystallisation from a strongly acidic aqueous solution calciumtetrahydrogen-hexaoxo-diperiodatetetrahydrate CaH4I2O10 ∙ 4 H2O has been obtained. In the structure of this compound (S.G. C2/c, Nr. 15), Z = 4, a = 1986,6(4), b = 564,2(1), c = 1149,4(20) pm, β = 120,62(3)°) centrosymmetric H4I2O10 2− anions in the form of edge-sharing octahedra form layers via hydrogen bonds originating from the acidic, trans-configurated OH groups of the anions. IR and Raman spectra are analysed with respect to the hydrogen bond system and the internal vibrations of the periodate anion. The dehydration of the compound takes place via Ca(IO4)2 ∙ 5 H2O and Ca(IO4)2 ∙2H2O leading at 143°C to the anhydrous metaperiodate Ca(IO4)2 which decomposes above 248°C to Ca(IO3)2.

The magnetic properties of the new polymorphic FeIn2S2Se2 compound are presented. The system crystallizes in the aFeGa2S4 structure at low temperatures, and undergoes a transition to a MgAl2S4-type structure at T48501C. For this high-temperature phase, low-field magnetization data show a peak at T1=12.5(5) K, below which magnetic irreversibility is observed. High-temperature susceptibility fits indicate the presence of antiferromagnetic interactions with a high degree of frustration. The effective magnetic moment leff=4.54(3) lB agrees with the expected 3d 6 (S=2) configuration for Fe 2+ .

The crystal structures of MnSc2S4 and CdSc2S4 have been determined from single crystal X-ray diffraction data. MnSc2S4 crystallises in a normal spinel structure (space group Fd 3 m) while for CdSc2S4 prepared at 900°C space group F 4 3m is observed. In the structure of CdSc2S4 the tetrahedral 8a site of the spinel structure is split into two different sites one of which exhibits a site occupation factor (sof) of only 0.9. A corresponding amount of Cd is found in an additional octahedral site (sof=0.1). The structure can be looked at as a transition state between the spinel and the sodium chloride structure. CdSc2S4 prepared at 600°C adopts a normal spinel structure (space group Fd 3 m) as has been elucidated from X-ray powder diffraction data by Rietveld analysis. The structure of FeSc2S4 has been determined from X-ray powder data by Rietveld analysis. FeSc2S4 crystallises in a normal spinel structure.

The system (1− x )FeIn 2 S 4 – x FeIn 2 Se 4 has been investigated by X-ray powder methods. The subsolidus phase diagram is constructed in the temperature interval 600–1000°C. The spinel type FeIn 2 S 4 exhibits a phase width up to the composition FeIn 2 S 3 Se and the layered FeIn 2 Se 4 is formed for 1≥ x ≥0.65. A new layered compound is formed for 0.55≥ x ≥0.4 which crystallizes at temperatures below 850°C in an α-FeGa 2 S 4 structure with a =363.6 pm and c =1207.1 pm ( x =0.5) for the hexagonal cell and at higher temperatures in the MgAl 2 S 4 -type with a =393.9 pm and c =3843.2 pm ( x =0.5) for the hexagonal cell. Both structures have been refined by the Rietveld-method. All phase boundaries are nearly independent from temperature.

The crystal structure of Rb3NbO8 (SG I4̅2m, Nr. 121) has been determined on single crystals to a final R = 0.041. The structure is isotypic to the K3CrO8 type. Vibrational spectra of the title compound have been recorded on powdered samples and are discussed with respect to the internal vibrations of the peroxo-group and the dodecahedral NbO8 3- ion. The stretching vibrations of the O2 2- groups are found at 838 (Raman) and 813 cm- 1(IR). A factor group analysis for the K3CrO8 type is given.

The title systems have been investigated by X-ray powder diffraction methods on samples quenched at 1300, 1100 and 900 K. A large temperature dependent area is found in the Ge-rich part of the phase diagram in which the samples form glasses. Two new crystalline compounds of composition 0.42CaS/0.15Ga 2 S 3 /0.4GeS, and 0.4SrS/0.15Ga 2 S 3 /0.45GeS 2 have been found. According to powder diffraction data they both crystallize tetragonally with a = 925.0(1), c = 602.4(1) pm for the Ca compound and a = 940.3(1), c = 618.9(1) pm for the Sr compound.

The layered chalcogenides CoGa1.7Ti0.3S4, CoGa1.7V0.3, CoGa1.6Cr0.4S4, CoGaInS4, MnGa1.5Cr0.5S4, MnGa1.4Sc0.6S4, MnGa0.8In1.2S4, MnIn2S1.6Se2.4 and CdIn2S2.1 Se1.9 have been investigated under high-pressure - high-temperature conditions (p ≤ 60 kbar, T ≤ 1600°C). MnIn2S1.6Se2.4 and CdIn2S2.1,S1.9 show a phase transition to spinel-type compounds (a = 11.022(2) and a = 11.059(1) Å, respectively). MnGa0.8In1.2S4 forms a high-pressure polymorph with an olivine-type structure (a = 12. 856(3), b = 7.500(3), c = 6.128(2)Å. All other compounds decompose under the conditions applied. The results of a Rietveld structure refinement for the two high-pressure spinels are presented

The title systems have been investigated on samples quenched at 700, 800 and 1000 °C. Five new compounds have been obtained and characterized by X-ray powder diffraction: Spinel type MgGa0.2Cr1.8S4, two compounds crystallizing in the olivine structure, MgGaCrS4 and MgGaInS4, and two layered materials, MgGa1.5Cr0.5S4 and MgGa1.5In0.5S4. Lattice para­ meters and phase widths of the compounds are given.

The mixed valence compound Ga1.93V0.97S4 has been prepared and characterized by X-ray powder methods. The compound crystallizes in an α-FeGa2S4 structure. The lattice parameters of the hexagonal cell are a = 363.6 and c = 1207.1 pm. The structure has been refined by Rietveld methods.

Lattice dynamical calculations for thiogallate-type compounds A Ga 2 X 4 with A = Cd or Hg, and X = S or Se have been performed on the basis of a short-range force constant model. Discrepancies in the experimental frequencies and crystal structures reported for these compounds in the literature by different groups are discussed with respect to the short-range force constants and potential energy distributions resulting from our calculations.

The title system has been investigated by X-ray powder diffraction methods on samples tempered at 1300, 1100 and 900 K. A large temperature-dependent area is found in which the samples form glasses. A new crystalline compound of composition Ba2.7Ga5.4Ge3.6S18 has been found, crystallizing trigonally in space group R3 with a = 9.600 A and c = 8.684 A . The crystal structure of this compound has been determined from single-crystal X-ray diffraction data and refined to R = 0.101 (Rw = 0.13). Ba and S together form a distorted c.c.p. array in which Ga and Ge occupy tetrahedral sites.

The system (1 - x)NiIn2S4 - xNiIn2Se4 has been investigated by X-ray powder methods. The subsolidus phase diagram is constructed in the temperature interval 600 -1000 °C. The spinel type NiIn2S4 exhibits a phase width up to the composition NiIn2S2Se2 at 900 °C and NiIn2S2.8Se1.2 at 600 °C. A new layered compound is formed for 0.7 ≥ x ≥ 0.5 at 600 °C and for x = 0.6 at 900 °C which crystallizes in the MgAl2S4-type with a = 392.4 and c = 3739.6 pm (x = 0.6) for the hexagonal cell.

In the quasibinary system MnIn 2 S 4 -MnIn 2 Se 4 a series of solid solutions of general formula MnIn 2 S x Se 4- x exists for 2.4 ≥ x ≥ 0.2 with the layered MgAl 2 S 4 structure. The samples have been characterized by X-ray powder diffraction and investigated by electrical measurements and diffuse reflectance spectroscopy. The compounds are semiconductors with optical band gaps varying between 1.6 and 1.2 eV depending on x . From Arrhenius plots of the conductivity data at least two different activation energies E a can be obtained: in the temperature interval from 50 to 200°C we find E a = 0.5 eV, independent of the composition of the samples, while in the high temperature region from 200 to 400°C, E a varies with x from 1.35 to 0.56 eV.

The systems CoGa 2- x Sc x S 4 , ZnGa 2- x Sc x S 4 and CdGa 2- x Sc x S 4 were investigated by X-ray powder methods on polycrystalline samples quenched at 800 and 1000°C. Three new compounds were obtained: CoGa 1.8 Sc 0.2 S 4 ( a =366.1 pm, c =1208.4 pm) and ZnGaScS 4 ( a =373.3 pm, c =1222.8 pm), both crystallizing in an FeGa 2 S 4 -type structure, and a spinel-type CoGa 0.2 Sc 1.8 S 4 ( a =1043.3 pm). Formation of a quaternary compound could not be obtained in the cadmium system.

Quaternary tellurides Cu2MM′Te4 (M = Zn, Cd, Hg and M′ = Si, Ge, Sn) have been prepared by solid state reactions and characterized by X-ray powder methods. All 9 compounds crystallize in a stannite type structure.

The crystal structure of CoGaInS4 has been determined from single crystal X-ray diffraction data and refined to R = 0.03. It crystallizes in the trigonal FeGa2S4 type (space group P 3 m1 , No. 164, a = 3.759(1), c = 12.184(2) A, Z = 1) with the following cation distribution: (Co0.61In0.39Ga)t(Co0.39In0.61)oS4. The system xCoGa2S4-(1 − x)CoIn2S4 is quasibinary. The compound CoGaInS4 has a large region of homogeneity with a marked dependence on temperature, ranging from x = 0.2 to x = 0.8 at 800°C. Compounds with high indium content show a phase transition to the ZnIn2S4(IIIa) type at 1000°C. Electronic spectra have been recorded on samples with different composition and on samples quenched from different temperatures.

Lattice dynamical calculations of the spinel type MCr2S4 (M = Mn, Fe, Cd) have been done using various potential models (short-range, rigid-ion, polarizable-ion). The main results are that (i) the vibrational modes (eigenvectors) and potential energy distributions of the Raman and IR allowed phonon modes of the three chromium sulfides are very similar, (ii) the A-X and B-X short-range force constants (referring to AB2X4) strongly depend on the structural parameter u, i.e., the tetrahedral A-X force constants are smaller than the respective octahedral B-X ones opposite to previous calculations on the basis of an ideal spinel structure with u = 0.25, (iii) bending force constants (X-A-X and X-B-X), but not X-X and B-B repulsive forces, are negligible, (iv) in the case of the breathing mode of the tetrahedral AX4 unit (species A1g) the demand on B-X and X-X (stretching and repulsion) forces is larger than that on the A-X force, and (v) the effective dynamic charges of the bivalent metal ions are nearly zero.

Structure field maps for ternary sulfides crystallizing in common AB 2 X 4 structures are given. They have been obtained from a plot of mean values of pseudopotential radii. There is a good separation of the fields for the different structures. The maps are used to predict possible compositions for new quaternary compounds of ZnIn 2 S 4 type.

The system MgGa2S4MgSc2S4 was studied by X-ray diffraction methods on samples quenched from 800 to 1000°C. Two new compounds MgGaxSc2−xS4 are obtained: for x = 1.6 a new material with FeGa2S4 type structure (trigonal, P 3 m1 (No. 164), a = 373.7(1), c = 1222.0(2) pm) and for x = 1.0 a new olivine type compound (orthorhombic, Pnma (No. 62), a = 1278.5(3), b = 741.9(1), c = 607.2(1) pm). The crystal structure of the olivine type compound MgGaScS4 was determined from single-crystal X-ray diffraction data and refined to R = 0.025. The octahedral 4a site is occupied by 0.7 Sc and 0.3 Mg, the 4c site, which is octahedrally coordinated also by 0.3 Sc and 0.7 Mg, and the tetrahedrally coordinated 4c site by Ga. An analogous cation distribution is found for the olivine MnGaScS4.

The results of a factor group analysis, the symmetry coordinates and vibrational modes of the lattice vibrations of compounds crystallizing in NiAs structure respectively NiAs defect structure (Fe3Se4 type) are presented. A normal coordinate treatment of the NiAs structure is performed using the GF-matrix-method assuming a valence force field with 3 force constants.

Force constants and normal coordinates of MnS2 , FeS2 , RuS2, RuSe2, RuTe2, OsS2 and PtP2 are calculated based on the five ir active vibrations of the pyrite lattice. By setting up a valence force field consisting of short and long range M -X, X2 -X2 and M -M stretching constants it has proved possible to obtain good agreement between experimental and calculated frequencies with expection of FeS2 and RuS2 . The force constants corresponding to the shortest metal chalcogen distances (MnS2: 0.30, RuSe2: 0.88, RuTe2: 0.62, OsS2: 1.32, PtP2: 1.22 mdyn/Å) are mainly responsible for the ir frequencies. For RuSe2 and RuTe2, the forces between adjacent X2 groups are not negligible. Whereas the force constants of OsS2 and PtP2 are of comparable strength, the forces in MnS2 are significantly weaker than those in the other compounds. The normal coordinates of MnS2, OsS2 and PtP2 , and RuSe2 and RuTe2 show significant differences according to both the contribution of the 6 symmetry coordinates to the 5 ir active vibrations and the assignment of the spectra.

The Raman and infrared reflection spectra of the spinel-type halidesLi 2 M II Cl 4 ( M II = Mg, V, Cr, Mn, Fe, Co, Zn, Cd) and Li 2 MnBr 4 including Kramers-Kronig analyses and oscillator-fit calculations are presented. These results are discussed in terms of (i) fast ionic conductivity, (ii) cation distribution, i.e., normal (Li 2 ZnCl 4 ) and inverse spinels, 1:1 ordering of Li and M II in the octahedral sites (Li 2 CoCl 4 ), (iii) phase transitions to an ordered (LiVo 2 type) and disordered NaCl defect structure, and (iv) two-mode behavior of the phonon modes.

On the basis of the rigid ion model and polarizable ion model, lattice dynamical calculations have been carried out for the fluorohalides BaFCl and BaFBr and for the oxyhalides LaOCl, LaOBr, YOCl, SmOCl and GdOCl which crystallize with the tetragonal Matlockite-type structure (PbFCl-type). The results of these calculations: short range force constants, effective dynamical charges and polarizabilities are communicated and discussed. Bonding in the fluorohalides is much more ionic than in the oxyhalides.

The phase diagrams of the quaternary systems M SCr 2 S 3 In 2 S 3 , with M = Co, Cd, and Hg, were studied with the help of X-ray powder photographs of quenched samples, high-temperature X-ray diffraction patterns, DTA and TG measurements, and far-infrared spectra. Because indium sulfides do react with silica tubes, alumina crucibles must be used for annealing the samples. Complete series of mixed crystals are formed among the spinel-type compounds M Cr 2 S 4 , M In 2 S 4 ( M = Cd, Hg), and In 2 S 3 . HgIn 2 S 4 is decomposed at temperatures above 300°C. In the sections CoCr 2 S 4 CoIn 2 S 4 and CoCr 2 S 4 In 2 S 3 relatively large miscibility gaps exist due to the change from normal to inverse spinel structure. But the interchangeability of both systems increases with increasing temperature, and at temperatures above 1000°C, complete series of solid solutions are formed, which can be quenched to ambient temperature. Superstructure ordering like that of ordered α-In 2 S 3 has been found in the In-rich region of the M In 2 S 4 In 2 S 3 solid solutions. The unit cell dimensions of all stoichiometric and phase boundary compounds, e.g., Cd 1.15 In 1.9 S 4 , including the chromium spinels M Cr 2 S 4 ( M = Mn, Zn) and ZnCr 2 Se 4 , are given and discussed in terms of possible deviations from stoichiometry.

The quasibinary systems MGa2S4MCr2S4 are studied for M = Zn, Cd, and Hg by X-ray investigations on powdered samples. The end members of these series show no detectable phase width. The formation of quaternary compounds is not observed. A new sulfide CoGa1.5Cr0.5S4 is obtained in the system CoGa2S4CoCr2S4 and characterized by X-ray and IR studies. CoGa1.5Cr0.5S4 is isomorphous with α-FeGa2S4 and crystallizes trigonally (space group P 3 m1 ) with a = 363.7(1) and c = 1200.7(1) pm. A study of the extension of the phase fields for this compound and the spinel CoCr2S4 in the system CoGa2S4CoCr2S4Cr2S3Ga2S3 is also undertaken.

The infrared spectra of spinel-type compounds A+A3+ Cr4X8 (A+ = Li, Cu, Ag; A3+ = Al, Ga, In; X = S, Se) have been measured. The spectra show that the spinels LiGaCr4S8, LiInCr4S8, CuGaCr4S8, CuInCr4S8, AgInCr4S8, CuGaCr4Se8, CuInCr4Se8, and AgInCr4Se8, whose structures cannot be determined by X-ray methods in all cases, have a structure with 1:1 ordering on the tetrahedral site (space group F 4 3m ). No ordering takes place in AgGaCr4S8. The spectra of the ordered spinels are discussed in relation to two-mode type spectra of spinel mixed crystals.

The quasi-binary systems Zn1-xCdxAl2S4, ZnAl2(1-x)Ga2xS4 and ZnAl2S4(1-x)Se4x have been investigated by X-ray diffraction and vibrational spectroscopy. In the spinel ZnAI2S4 up to 20% of Zn can be replaced by Cd. In the two other systems, ZnAl2S4 has no detectable homogeneity range. The thiogallate phases have much broader ranges of homogeneity. The compositions of the compounds at the phase boundary of the thiogallate phase are Zn0.4Cd0.6Al2S4, ZnGa0.4Al1.6S4, and ZnAl2S2.8Se1.2. At approximately 950 °C ZnAl2Se4 undergoes a reversible phase transition to a wurtzite-type structure. This phase transition is also observed for the solid solutions ZnAl2S4(1-x)Se4x; with 1.0 > x > 0.3. The FIR spectra are discussed.

The far-infrared reflection spectra of hot-pressed samples of the spinels M Cr 2 S 4 with M =Mn, Fe, Co, Zn, Cd, and Hg, MCr 2 Se 4 with M =Zn, Cd, and Hg, and M In 2 S 4 with M =Mn, Fe, Co, Ni, Cd, Hg have been recorded in the range from 40 to 700 cm −1 . The spectra show four reststrahlen bands in the case of normal spinels and up to five in the case of inverse spinels. The transverse and longitudinal optical phonon frequencies at wave vector ∣ q ∣ ⋍ 0 are determined by Kramers-Kronig analysis and the classical oscillator-fit method. Effective ionic charges (normalized splitting, transverse effective charge, Szigeti charge) were calculated from the experimentally determined TO–LO splittings and from the high frequency dielectric constants. The obtained data reveal an increasing covalency of the chalcide spinels in the order selenides > sulfides, chromium compounds > indium compounds, inverse spinels > normal spinels,Ni M′ 2 X 4 > Co M′ 2 X 4 > Fe M′ 2 X 4 ,Mn M′ 2 X 4 > Hg M′ 2 X 4 > Zn M′ 2 X 4 >CD M′ 2 X 4 .

The sections Li 2 M Cl 4−4x Br 4x of the quaternary systems LiCl-LiBr- M Cl 2 - M Br 2 with M = Mn, Cd, and Fe were studied by high-temperature X-ray diffraction patterns and DTA and DSC measurements. In the quasibinary lithium manganese halide system complete series of solid solutions exist between the inverse spinels Li 2 MnCl 4 and Li 2 MnBr 4 . Li 2 MnBr 4 and solid solutions with x > 0.54 undergo phase transitions to tetragonal spinels at lower temperatures. In the nonquasibinary system with M = Cd, only at temperatures near 400°C a complete series of mixed crystals is formed. At lower temperatures the system is mainly two-phase with rock salt-type Li 1− y Cd 0.5 y Cl 1− x Br x and cadmium chloride-type Cd 1− y Li 2 y Cl 2−2 x Br 2 x solid solutions in equilibrium. The lithium iron halide system is similar to that of cadmium, but spinel-type Li 2 FeBr 4 does not exist at any temperature. The manganese and cadmium halide spinels and spinel solid solutions undergo phase transitions to NaCl defect structures at elevated temperatures.

The crystal structure of Zn 1.25 In 2.5 S 3 Se 2 was determined from single crystal data. The compound crystallizes in the trigonal space group P3m1-D 3 3d (No 164) with Z = 2 . The lattice constants (hexagonal setting) are a = 3.927(1) and c = 31.83(1) A˚. The structure is of a layer type and may be described as a slightly distorted hexagonal closed packing of the anions with two In 3+ in octahedral voids and all other cations in tetrahedral coordination. The isotypic compounds Cd 0.5 Ga 2 InS 5 and Hg 0.8 Ga 1.6 In 1.2 S 5 have lattice parameters a = 3.809(1), c = 30.64(1) A˚, and a = 3.820(1), c = 30.929(3) A˚, respectively.

Tetragonal aluminium sulfide crystallizing with the spinel defect structure of the β-In2S3 type has been prepared at ambient pressure. IR and Raman spectra of this compound and of α-Al2S3 are reported and discussed in relation to their crystal structures

The system CdIn 2 S 4− x Se x is investigated by means of X-ray diffraction. There are three phases present in the system: (i) a cubic spinel phase for x = 0 to x = 1.25, (ii) a rhombohedral phase of ZnIn 2 S 4 type for x = 1.75 to x = 2.75, and (iii) a tetragonal thiogallate phase for x = 3.5 to x = 4.0.

Three new compounds, Ag2HgGeS4, Ag2HgSnS4, and Ag2HgSnSe4, crystallizing in the wurtzstannite type structure have been prepared by solid state reactions at 700°C and characterized by X-ray powder methods. A fourth compound of similar composition Ag2HgGeSe4, with an hitherto unknown structure crystallizes cubically with a = 10.796 A.

The following sulphides were precipitated with hydrogen sulphide from solutions of naphthenates in organic solvents: In2S3, CoS, NiS, CuS, ZnS, CdS, HgS, PbS, Ag2S and the thiospinels NiIn2S4, CdIn2S4 and HgIn2S4. Not precipitated are chromium (II) and chromium (III). The ir-spectra of the naphthenates are discussed.