Triclinic Structure of Birefringent Crystals of K(Al0.95Cr0.05)(SO4)2⋅12H2O

The crystal structure of alum K(Al_0.95Cr_0.05)(SO₄)₂12H₂O possessing anomalous birefringence was refined in space groups Pa3 and P1 (a = b = c = 12.165(2) , R = 0.0587). The distortions of cubic symmetry are attributed to the peculiarities of the orientational disorder in the distribution of SO₄ tetrahedra and to the different degrees of distortion of the aluminum octahedra.     

Incorporation of Sulfate or Selenate Groups into Oxotellurates(IV): III. Compounds with Magnesium or Zinc

The mixed oxochalcogenate compounds Mg₂(SO₄)(TeO₃)(H₂O), Mg₃(SO₄)(TeO₃)(OH)₂(H₂O)₂, Zn₂(SeO₄)(TeO₃), and Zn₄(SO₄)(TeO₃)₃ were obtained under hydrothermal conditions (210 °C, autogenous pressure). Structure analyses using single‐crystal X‐ray data revealed tellurium in all four compounds to be present in oxidation state +IV, whereas sulfur or selenium atoms exhibit an oxidation state of +VI. In the crystal structures of the two magnesium compounds, [MgO₅(H₂O)] octahedra [Mg₂(SO₄)(TeO₃)(H₂O) structure, isotypic with the Co and Mn analogues] or [MgO₄(OH)₂] and [MgO₄(OH)₂(H₂O)₂] octahedra [Mg₃(SO₄)(TeO₃)(OH)₂(H₂O)₂ structure, novel structure type] as well as trigonal‐pyramidal TeO₃^2– anions make up metal oxotellurate sheets, which are bridged by SO₄^2– anions. The polar crystal structure of Zn₂(SeO₄)(TeO₃) is isotypic with Zn₂(MoO₄)(TeO₃) and consists of [ZnO₄] tetrahedra, [ZnO₆] octahedra, SeO₄^2– and TeO₃^2– anions as principal building units that are connected into a framework structure. Such a structural arrangement, with basically the same coordination polyhedra as in Zn₂(SeO₄)(TeO₃) but with SO₄^2– instead of SeO₄^2– anions, is also found in the tellurium‐rich compound Zn₄(SO₄)(TeO₃)₃ that crystallizes in a novel structure type.     

Organically‐Templated Zinc and Thorium Sulfates with Chain and Layered Structures

Amine‐templated zinc sulfates of the formulae, [Zn(SO₄)(H₂O)₂(C₁₀N₂H₈)] ( I ) and [C₃N₂H₁₂][Zn(SO₄)] ( II ) both with linear structures have been prepared under hydro/solvothermal conditions. Of these, I has the chain structure formed by ZnO₄N₂octahedra and SO₄ tetrahedra, while II comprises ladders formed by corner‐sharing four‐membered rings. Amine‐templated thorium sulfates of the formula [HN(CH₂)₆NH]₂[Th₂(SO₄)₆(H₂O)₂]·2H₂O, ( III ) and [H₂N(CH₂)₄NH₂][Th₃(SO₄)₇(H₂O)₄]·5H₂O ( IV ) are also obtained under hydrothermal conditions. III has a sheet structure consisting of cages whereas IV has a two‐dimensional structure derived from the connectivity of ladders.     

Crystal structures of sodium magnesium selenate decahydrate,Na2Mg(SeO4)2·10H2O,a new selenate salt,and sodium magnesium selenate dihydrate,Na2Mg(SeO4)2·2H2O

Metal selenates crystallize in many instances in isomorphic structures of the corresponding sulfates. Sodium magnesium selenate decahydrate, Na₂Mg(SeO₄)₂·10H₂O, and sodium magnesium selenate dihydrate, Na₂Mg(SeO₄)₂·2H₂O, were synthesized by preparing solutions of Na₂SeO₄ and MgSeO₄·6H₂O with different molar ratios. The structures contain different Mg octahedra, i.e. [Mg(H₂O)₆] octahedra in the decahydrate and [MgO₄(H₂O)₂] octahedra in the dihydrate. The sodium polyhedra are also different, i.e. [NaO₂(H₂O)₄] in the decahydrate and [NaO₆(H₂O)] in the dihydrate. The selenate tetrahedra are connected with the chains of Na polyhedra in the two structures. O—H…O hydrogen bonding is observed in both structures between the coordinating water molecules and selenate O atoms.     

Hydrothermal synthesis and crystal structure of Cs6[(UO2)4(W5O21)(OH)2(H2O)2]: a new polar uranyl tungstate

The hydrothermal reaction of UO₃, WO₃, and CsIO₄ leads to the formation of Cs₆[(UO₂)₄(W₅O₂₁)(OH)₂(H₂O)₂] and UO₂(IO₃)₂(H₂O). Cs₆[(UO₂)₄(W₅O₂₁)(OH)₂(H₂O)₂] is the first example of a hydrothermally synthesized uranyl tungstate. It's structure has been determined by single-crystal X-ray diffraction. Crystallographic data: tetragonal, space group I4 cm, , , Z=4, MoKα, , R(F)=2.84% for 135 parameters with 2300 reflections with I>2σ(I). The structure is comprised of two-dimensional anionic layers that are separated by Cs⁺ cations. The coordination polyhedra found in the novel layers consist of UO₇ pentagonal bipyramids, WO₆ distorted octahedra, and WO₅ square pyramids. The UO₇ polyhedra are formed from the binding of five equatorial oxygen atoms around a central uranyl, UO₂²⁺, unit. Both bridging and terminal oxo ligands are employed in forming the WO₅ square pyramidal units, while oxo, hydroxo, and aqua ligands are found in the WO₆ distorted octahedra. In the layers, four (UO₂)O₅ polyhedra corner share with equatorial oxygen atoms to form a U₄O₂₄ tetramer entity with a square site in the center; a tungsten atom populates the center of each of these sites to form a U₄WO₂₅ pentamer unit. The pentamer units that result are connected in two dimensions by edge-shared dimers of WO₆ octahedra to form the two-dimensional [(UO₂)₄(W₅O₂₁)(OH)₂(H₂O)₂]^6- layers. The lack of inversion symmetry in Cs₆[(UO₂)₄(W₅O₂₁)(OH)₂(H₂O)₂] can be directly contributed to the WO₅ square pyramids found in the pentamer units. In the structure, all of these polar polyhedra align their terminal oxygens in the same orientation, along the c axis, thus resulting in a polar compound.     

Synthesis, characterization and structure determination of two isotypes of a layered aluminophosphate with a new 2D network topology

Two isotypes of a new layered aluminophosphate, further denoted MDAP-3 and MDAE-1, have been synthesized under hydrothermal conditions using N-methyl-1,3-propanediamine and N-methyl-ethylenediamine, respectively. MDAP-3, with the empirical formula [Al₂(HPO₄)(PO₄)₂](C₄N₂H₁₄)(H₂O), crystallizes in the orthorhombic space group Pna2(1) (No. 33) with , , , Z=4, R₁=0.0498 and wR₂=0.1217. The second solid, MDAE-1, with the empirical formula [Al₂(HPO₄)(PO₄)₂](C₃N₂H₁₂)(H₂O), crystallizes in the same space group with , , , Z=4, R₁=0.0407 and wR₂=0.0954. The two compounds possess the same layer topology. Inorganic layers contain PO₃=O, PO₃OH, AlO₄ and AlO₆ polyhedra, linked together to generate a new 4×8 net. MDAP-3 and MDAE-1 represent the first examples of two-dimensional layered aluminophosphates with the Al₂P₃O₁₂ stoichiometry, and containing AlO₆ octahedra.     

Co3{CH3C(NH3)(PO3H)(PO3)}2 {CH3C(NH3)(PO3H)2}2(H2O)4·2H2O: A cobalt 1-aminoethylidenediphosphonate with a layer structure

This paper describes the structure and magnetic properties of a novel cobalt 1-aminoethylidenediphosphonate compound, namely Co₃{CH₃C(NH₃)(PO₃H)(PO₃)}₂{CH₃C(NH₃)(PO₃H)₂}₂(H₂O)₄·2H₂O (1). The structure contains a trimer unit of Co₃{CH₃C(NH₃)(PO₃H)(PO₃)}₂ in which two equivalent phosphonate ligands chelate and bridge the three cobalt ions. Each trimer unit is further linked to its four equivalent neighbors through corner-sharing of CoO₆ octahedra and CPO₃ tetrahedra, forming a two-dimensional layer in the bc-plane which contains 12-membered rings. These layers are connected to each other by extensive hydrogen bonds. Magnetic studies show that weak antiferromagnetic interactions are mediated between the cobalt ions. Crystal data for 1: monoclinic, space group C2/c, a=27.727(4), b=7.1091(11), , β=118.488(3), , Z=2.     

Synthesis, structure, magnetic susceptibility and Mössbauer and Raman spectroscopies of the new oxyphosphate Fe0.50TiO(PO4)

A new iron titanyl oxyphosphate Fe_0.50TiO(PO₄) was synthesized by both solid-state reaction and Cu²⁺-Fe²⁺ ion exchange method. The material was then characterized by X-ray diffraction, Mössbauer spectroscopy, magnetic susceptibility measurements and Raman spectroscopy. The crystal structure of the compound was refined, using X-ray powder diffraction data, by Rietveld profile method; it crytallizes in the monoclinic system, space group P2₁/c (No.14), with , , , β=120.36°(1), and Z=4. The volume of the title compound is comparable to those of the M_0.50^IITiO(PO₄) series, where M^II=Mg, Co, Ni and Zn. The framework is built up from [TiO₆] octahedra and [PO₄] tetrahedra. [TiO₆] octahedra are linked together by corners and form infinite chains along the c-axis. Ti atoms are displaced from the center of octahedral units showing an alternating short distance (1.73 Å) and a long one (2.22 Å). These chains are linked together by [PO₄] tetrahedra. Fe²⁺ cations occupy a triangle-based antiprism sharing two faces with two [TiO₆] octahedra. Mössbauer and magnetic measurements show the existence of iron only in divalent state, located exclusively in octahedral sites with high spin configuration (t_2g⁴e_g²). Raman study confirms the existence of Ti-O-Ti chains.     

Die Kristallstruktur von Trikobalt(II)-dihydroxidsulfat-dihydrat,Co3(OH)2(SO4)2 · 2 H2O

Tricobalt (II)-dihydroxidesulfate-dihydrate, Co₃(OH)₂(SO₄)₂ · 2H₂O, is orthorhombic: a = 7.21, b = 9.77, c = 12.86 Å, V = 905.9 ų, space group D-Pbcm with four formula units per cell. The atomic positions have been determined by threedimensional Patterson and Fourier synthesis and full-matrix least-squares refinement of single crystal X-ray diffraction data. The structure shows infinite chains [001] of Co? O octahedra sharing one edge with each other. These chains are linked together by alternating SO₄ tetrahedra and additional Co? O octahedra, thus giving rise to a three-dimensional network of polyhedra. There is no similarity to the well known layer structures of most hydroxide salts of divalent metals. The SO₄ tetrahedra are regular while the Co? O octahedra show considerable distortion. The water molecule is coordinated to one Co atom and bonded to sulfate oxygen by two weak hydrogen bridges.     

Hydrogen bond strength in chromates with kröhnkite-type chains, K2Me(CrO4)2·2H2O (Me = Mg, Co, Ni, Zn, Cd)

Infrared spectra of the title compounds with kröhnkite-type infinite octahedral–tetrahedral chains, K₂Me(CrO₄)₂·2H₂O (Me = Mg, Co, Ni, Zn, Cd), are presented in the regions of the uncoupled O–D stretching modes of matrix-isolated HDO molecules (isotopically dilute samples) and water librations. The strengths of the hydrogen bonds are discussed in terms of the respective O_wO bond distances, the Me–water interactions (synergetic effect), the proton acceptor capability of the chromate oxygen atoms as deduced from Brown's bond valence sum of the oxygen atoms. The spectroscopic experiments reveal that hydrogen bonds of medium strength are formed in the chromates. The hydrogen bond strengths decrease in the order Cd > Zn > Ni > Co in agreement with the decreasing covalency of the respective Me–OH₂ bonds in the same order, i.e. decreasing acidity of the water molecules. The infrared band positions corresponding to the water librations confirm the claim that the hydrogen bonds in K₂Cd(CrO₄)₂·2H₂O are stronger than those formed in K₂Mg(CrO₄)₂·2H₂O on one hand, and on the other—the hydrogen bonds in K₂Ni(CrO₄)₂·2H₂O are stronger than those in K₂Co(CrO₄)₂·2H₂O.     

Hydrothermal synthesis and structure characterization of a new 3D vanadium hydrogen phosphite with 14-ring channels: (C5N2H14)[VO(H2O)]3(HPO3)4·H2O

A new 3D vanadium hydrogen phosphite, (C₅N₂H₁₄)[VO(H₂O)]₃(HPO₃)₄·H₂O, has been prepared by hydrothermal reactions and characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, and magnetic techniques. It crystallizes in the triclinic space group P-1 (no. 2) with , , , α=76.124(3)°, β=83.726(4)^o, γ=75.222(4)^o, Z=2. The structure is built up from sharing equatorial oxygen atoms of VO₅(H₂O) octahedra with HPO₃ tetrahedra, which can be viewed as a (3,4) connected net. The framework is mainly constructed by two types of four-ring related chains. Intrachain and interchain hydrogen bonds play an important role on supporting the framework structure. The 14-ring tunnels in the structure are filled with 1-methypiperazinium and water molecules, which also contribute the hydrogen bonding with the vanadium phosphite framework.     

Synthesis and crystal structures of two new Zn(II) coordination polymers with 4,4′-dipyridyl disulfide and dicarboxylate acid

The title compounds, Zn(C₅H₆O₄)(Dpds) · 5H₂O (I) and Zn(C₆H₈O₄)(Dpds) (II) (C₅H₈O₄ = glutaric acid, Dpds = 4,4??-dipyridyl disulfide, and C₆H₁₀O₄ = adipic acid), are two-dimensional metal-organic coordination polymers. In I, the tetrahedra coordinated Zn atoms are bridged by glutarate anions and Dpds ligand to form a 2D layer parallel to (001) plane, which are connected by the 1D water tape notated as T4(2)₅(2) to build up 3D supramolecular architecture. In II, both Dpds ligands and adipate anions act as bidentate bridges, connecting the Zn(II) centers in a tetrahedral coordination geometry into a two-dimensional (4,4) layer. Each layer polycatenates adjacent layers, exhibiting the rare combination of 2D ?? 2D parallels interpenetration.     

Three novel non‐centrosymmetric compounds of glycine: glycine lithium sulfate,glycine nickel dichloride dihydrate and glycine zinc sulfate trihydrate

The crystal structures of three compounds of glycine and inorganic materials are presented and discussed. The ortho­rhombic structure of glycinesulfatodilithium(I), [Li₂(SO₄)(C₂H₅NO₂)]_n, consists of corrugated sheets of [LiO₄] and [SO₄] tetrahedra. The glycine mol­ecules are located between these sheets. The main features of the monoclinic structure of di­aqua­di­chloro­glycinenickel(II), [NiCl₂(C₂H₅NO₂)(H₂O)₂]_n, are helical chains of [NiO₄Cl₂] octahedra connected by glycine mol­ecules. The orthorhombic structure of tri­aqua­glycinesulfatozinc(II), [Zn(SO₄)(C₂H₅NO₂)(H₂O)₃]_n, is made up of [O₃SOZnO₅] clusters. These clusters are linked by glycine mol­ecules into zigzag chains. All three compounds are examples of non‐centrosymmetric glycine compounds.     

Doppelkettenstruktur von (pipzH2)[MnF2(HPO4)(H2O)](H2PO4)

By adding piperazine to a hydrofluoric and phosphoric acid solution of Manganese(III) fluoride, the fluoride phosphate (pipzH₂)[MnF₂(HPO₄)(H₂O)](H₂PO₄) can be crystallized. Its structure is built by piperazinium(2+) cations, (H₂PO₄)^? anions, and an anionic double‐chain of [HPO₄] tetrahedra and [MnO₃F₂(H₂O)] octahedra. The structure is triclinic, space group P , Z = 2, a = 622.97(4), b = 923.46(6), c = 1183.62(7) pm, α = 98.343(6)°, β = 100.747(7)°, γ = 107.642(5)°, R = 0.0289. It is worth noting that a ferrodistortive Jahn‐Teller order is observed with [MnO₃F₂(H₂O)] octahedra strongly elongated along the F–Mn–OH₂ axes perpendicular to the chain plane. The structure is stabilized by very strong hydrogen bonds.     

Structures and syntheses of four Np sulfate chain structures: Divergence from U crystal chemistry

Four Np⁵⁺ sulfates, X₄[(NpO₂)(SO₄)₂]Cl (X=K, Rb) (KS1, RbS1), Na₃[(NpO₂)(SO₄)₂](H₂O)_2.5 (NaS1), and CaZn₂[(NpO₂)₂(SO₄)₄](H₂O)₁₀ (CaZnS1) were synthesized by evaporation of solutions derived from hydrothermal treatment. Their structures were solved by direct methods and refined on the basis of F² for all unique data collected with MoKα radiation and a CCD-based detector to agreement indices (KS1, RbS1, NaS1, CaZnS1) R₁=0.0237, 0.0593, 0.0363, 0.0265 calculated for 2617, 2944, 2635, 2572 unique observed reflections, respectively. KS1 crystallizes in space group P2/n, a=10.0873(4), b=4.5354(2), c=14.3518(6), β=103.383(1)°, , Z=2. RbS1 is also monoclinic, P2/n, with a=10.5375(8), b=4.6151(3), c=16.0680(12), β=103.184(1)°, , Z=2. NaS1 is monoclinic, P2₁/m, with a=7.6615(5), b=7.0184(4), c=11.0070(7), β=90.787(1)°, , Z=4. CaZnS1 is monoclinic, P2₁/m, with a=8.321(2), b=7.0520(2), c=10.743(3), β=91.758(5)°, , Z=2. The structures of KS1 and RbS1 contain chains of edge-sharing neptunyl hexagonal bipyramids, with sulfate tetrahedra attached to either side of the chain by sharing edges with the bipyramids. NaS1 and CaZnS1 both contain chains of neptunyl pentagonal bipyramids and sulfate tetrahedra in which each bipyramid is linked to four tetrahedra, three by sharing vertices and one by sharing an edge. Bipyramids are bridged by sharing vertices with sulfate tetrahedra. Each of these structures exhibits significant departures from those of uranyl sulfates.     

Hydrothermal synthesis and structure of organically templated chain, layered and framework scandium phosphates

Four scandium phosphate-based structures have been prepared hydrothermally in the presence of the primary diamines ethylenediamine and diaminobutane and the primary amine cyclohexylamine and characterised by single crystal and powder X-ray diffraction, ³¹P and ⁴⁵Sc solid-state MAS NMR and chemical analysis. Charge balancing protons in the structures are located using bond valence sum calculations and postulated hydrogen bonding networks. Compound 1, [(H₃NC₂H₄NH₃)₃][Sc₃(OH)₂(PO₄)₂(HPO₄)₃(H₂PO₄)], , a=5.4334(6), b=8.5731(9), , α=79.732(4), β=83.544(4), γ=80.891(5)°, Z=2, is built up of scandium phosphate ribbons, based on trimers of ScO₆ octahedra linked by OH groups. These trimers are joined through phosphate groups bound through three oxygens, and are decorated by phosphate groups linked by a single oxygen atom. The ribbons are arranged parallel to the a-axis and linked one to another by fully protonated ethylenediammonium ions. Compounds 2, [(H₃NC₄H₈NH₃)₃][(Sc(OH₂))₆Sc₂(HPO₄)₁₂(PO₄)₂], , a=13.8724(3), , Z=1, and 3, [(H₃NC₄H₈NH₃)₂(H₃O)][Sc₅F₄(HPO₄)₈], C2/m, a=12.8538(4), b=14.9106(4), , β=101.17(9)°, Z=2, were prepared using diaminobutane as the organic template in the absence and presence, respectively, of fluoride ions in the gel. Compound 2 has a pillared layered structure, in which ScO₆ octahedra are linked by three vertices of hydrogenphosphate groups into sheets and the sheets pillared by ScO₆ octahedra to give a three-dimensionally connected framework isostructural with a previously reported iron(III) hydrogenphosphate. The protonated diaminobutane molecules occupy cavities between the layers. Compound 3 has a layered structure in which isolated ScO₆ octahedra and tetrameric arrangements of ScO₄F₂ octahedra, the latter linked in squares through fluoride ions, are connected by phosphate tetrahedra that share two or three oxygens with scandium atoms. In this structure, the protonated diaminobutane molecules connect the layers, the -NH₃⁺ groups fitting into recesses in the layers. Compound 4, [(C₆H₁₁NH₃)][ScF(HPO₄)(H₂PO₄)], Pbca, a=7.650(3), b=12.867(5), , Z=8, the first scandium phosphate to be prepared with a monoamine, is also a layered solid. In this case, the layers contain single chains of ScO₄F₂ octahedra which share fluoride ions in trans positions. Phosphate tetrahedra bridge across scandiums via two of their four oxygens, both within the same chain and also to neighbouring chains to make up the layer. The protonated amine groups of the cyclohexylamine molecules achieve close contact with phosphates of the layer, while the cyclohexyl moieties, which are in the chair configuration, project into the interlayer space.     

Amine‐Templated One‐Dimensional Metal Sulfates Including a Mixed‐Valent Fe Compound with a Half‐Kagome Structure

Organically templated metal sulfates are relatively new. Six amine‐templated transition‐metal sulfates with different types of chain structures, including a novel iron sulfate with a chain structure corresponding to one half of the kagome structure, were synthesized by hydro/solvothermal methods. Amongst the one‐dimensional metal sulfates, [C₁₀N₂H₁₀][Zn(SO₄)Cl₂] ( 1 ) is the simplest, being formed by corner‐linked ZnO₂Cl₂ and SO₄ tetrahedra. [C₆N₂H₁₈][Mn(SO₄)₂(H₂O)₂] ( 2 ) and [C₂N₂H₁₀][Ni(SO₄)₂(H₂O)₂] ( 3 ) have ladder structures comprising four‐membered rings formed by SO₄ tetrahedra and metal–oxygen octahedra, just as in the mineral kröhnkite. [C₄N₂H₁₂][V^III(OH)(SO₄)₂]?H₂O ( 4 ) and [C₄N₂H₁₂][VF₃(SO₄)] ( 5 ) exhibit chain topologies of the minerals tancoite and butlerite, respectively. The structure of [C₄N₂H₁₂][H₃O][Fe^IIIFe^II F₆(SO₄)] ( 6 ) is noteworthy in that it corresponds to half of the hexagonal kagome structure. It exhibits ferrimagnetic properties at low temperatures and the absence of frustration, unlike the mixed‐valent iron sulfate with the full kagome structure.     

Synthesis, structure, and properties of chromium(III) sulfates

Reactions between CrO₃ and 50- are studied at temperatures up to the boiling point of the acid. Depending on the H₂SO₄ concentration and synthesis temperature, Cr₂(SO₄)₃, CrH(SO₄)₂, (H₃O)[Cr(SO₄)₂], Cr₂(SO₄)₃·H₂SO₄·4H₂O (gross formula), and (H₅O₂)[Cr(H₂O)₂(SO₄)₂], are obtained as identified reaction products in addition to the incompletely characterized chromic-sulfuric acid. The Cr^III-based sulfates are characterized by X-ray powder diffraction, thermogravimetric, and magnetic susceptibility measurements. The nuclear and magnetic structures of Cr₂(SO₄)₃ at are determined, the structure type of (H₃O)[Cr(SO₄)₂] is established, and the crystal structure of (H₅O₂)[Cr(H₂O)₂(SO₄)₂] is firmly stipulated. Magnetic susceptibility data suggest that the samples of CrH(SO₄)₂ are in a micro-crystalline rather than in an amorphous state. All Cr^III-based sulfates synthesized in this study appear to undergo paramagnetic-to-antiferromagnetic transitions at around .     

X-ray attenuation coefficient measurements for photon energies 4.508-13.375 keV in Cu, Cr and their compounds and the validity of the mixture rule

To investigate the validity of the mixture rule which is used to compute the mass attenuation coefficients in compounds, the total mass attenuation coefficients for Cu, Cr elements and Cu₂O, CuC₂O₄, CuCl₂·2H₂O, Cu(C₂H₃O₂)₂·H₂O, Cr₂O₃, Cr(NO₃)₃, Cr₂(SO₄)₃·H₂O, Cr₃(CH₃CO₇)(OH)₂ compounds were measured at photon energies between 4.508 and 13.375 keV by using the secondary excitation method. Ti, Mn, Fe, Ni, Zn, Ge, As, Rb elements were used as secondary exciters. 59.5 keV gamma rays emitted from an annular source were used to excite the secondary exciters and Kα (K-L₃, L₂) rays emitted from the secondary exciter were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. Our measurements indicate that the mixture rule is not a suitable method for the computation of mass attenuation coefficients of compounds especially at an energy that is near the absorption edge. Obtained values were compared with theoretical values.