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The structure of Ni(3-amino-4,4′-bipyridine)[Ni(CN)4] (or known as Ni-BpyNH2) in powder form was determined using synchrotron X-ray diffraction and refined using the Rietveld refinement technique (R= 8.8%). The orthorhombic (Cmca) cell parameters were determined to be a= 14.7218(3) Å, b= 22.6615(3) Å, c= 12.3833(3) Å, V= 4131.29(9) Å3, and Z= 8. Ni-BpyNH2forms a 3-D network, with a 2-D Ni(CN)4net connecting to each other via the BpyNH2ligands. There are two independent Ni sites on the net. The 2-D nets are connected to each other via the bonding of the pyridine “N” atom to Ni2. The Ni2 site is of six-fold coordination to N with relatively long Ni2–N distances (average of 2.118 Å) as compared to the four-fold coordinated Ni1–C distances (average of 1.850 Å). The Ni(CN)4net is arranged in a wave-like fashion. The functional group, –NH2, is disordered and was found to be in the m-position relative to the N atom of the pyridine ring. Instead of having a unique position, N has ¼ site occupancy in each of the four m-positions. The powder reference diffraction pattern for Ni-BpyNH2was prepared and submitted to the Powder Diffraction File (PDF) at the International Centre of Diffraction Data (ICDD).

Quaternary selenide, Pb4In2.6Bi3.4Se13(x= 2.4 member of the Pb4(InxBi6-xSe13solid solution), was synthesized by a solid-state technique, and its structure was determined using powder X-ray diffraction (XRD). Pb4In2.6Bi3.4Se13crystallizes in the orthorhombic space group Pbam(No. 55) with Z= 4. Lattice parameters and calculated density were determined to be a= 22.152(5) Å, b= 27.454(5) Å, and c= 4.1354(6) Å, V= 2515.0(11) Å3, and Dx=7.490 g cm−3. The structure consists of Z-shaped ribbon units and corner-shared infinite one-dimensional [InSe4]∞chains running parallel to the c-axis. The chains and ribbons are further connected by Pb atoms to form a three-dimensional network. Pb atoms are situated in the center of bicapped trigonal prisms. The compound exhibits a semiconductor feature. The Seebeck coefficient of Pb4In2.6Bi3.4Se13was found to be −180 μV K−1at 295 K and −380 μV K−1at 600 K. Combining the values of Seebeck coefficient, electrical conductivity, and thermal conductivity yield a figure of merit, ZT, of about 0.175 at 700 K. The powder XRD pattern of Pb4In2.6Bi3.4Se13was also determined.

X-ray reference powder patterns and structures have been determined for a series of cobalt- and tungsten-containing cubic alkaline-earth perovskites, (BaxSr1–x)2CoWO6(x= 0.1, 0.2, 0.3, 0.5, 0.7, and 0.9). The structure of the end members of the series, Sr2CoWO6and Ba2CoWO6, were tetragonal and cubic, respectively, agreeing with the literature data. From Rietveld refinements, it was found that when x= 0.1 and 0.2, the structure was tetragonal I4/m(a= 5.60481(6) and 5.62305(11) Å and c= 7.97989(12) and 7.9847(2) Å, respectively; Z= 2). When x> 0.2, the structure was cubic (Fm$\bar{3}$m, No. 225; Z= 4) (from x= 0.3 to 0.9, aincreases from 7.98399(13) to 8.08871(10) Å). This tetragonal series of compounds exhibit the characteristics of a distorted double-perovskite structure. The bond valence sum values for the alkaline-earth (Ba, Sr) sites in all (BaxSr1−x)2CoWO6members are greater than the ideal value of 2.0, indicating over-bonding situation, whereas for the W sites, as xincreases, a change from under-bonding to slightly over-bonding situation was observed. Density functional theory calculations revealed that while Sr2CoWO6is a semiconductor, Ba2CoWO6and SrBaCoWO6are half-metals. Powder X-ray diffraction patterns of this series of compounds (BaxSr1−x)2CoWO6, with x= 0.1, 0.2, 0.3, 0.5, 0.7, and 0.9, have been submitted to be included in the Powder Diffraction File.

Structure and optical properties have been successfully determined for a series of niobium- and tantalum-containing layered alkaline-earth silicate compounds, Ba3(Nb6−xTax)Si4O26(x= 0.6, 1.8, 3.0, 4.2, 5.4). The structure of this solid solution was found to be hexagonal P-62m(No. 189), with Z= 1. With xincreases from 0.6 to 5.4, the lattice parameter aincreases from 8.98804(8) to 9.00565(9) Å and cdecreases from 7.83721(10) to 7.75212(12) Å. As a result, the volume decreases from 548.304(11) to 544.479(14) Å3. The (Nb/Ta)O6distorted octahedra form continuous chains along the c-axis. These (Nb/Ta)O6chains are in turn linked with the Si2O7groups to form distorted pentagonal channels in which Ba ions were found. These Ba2+ions have full occupancy and a 13-fold coordination environment with neighboring oxygen sites. Another salient feature of the structure is the linear Si–O–Si chains. When xin Ba3(Nb6−xTax)Si4O26increases, the bond valence sum (BVS) values of the Ba sites increase slightly (2.09–2.20), indicating the size of the cage becoming progressively smaller (over-bonding). While SiO cages are also slightly smaller than ideal (BVS range from 4.16 to 4.19), the (Nb/Ta)O6octahedral cages are slightly larger than ideal (BVS range from 4.87 to 4.90), giving rise to an under-bonding situation. The bandgaps of the solid solution members were measured between 3.39 and 3.59 eV, and the x= 3.0 member was modeled by density functional theory techniques to be 3.07 eV. The bandgaps of these materials indicate that they are potential candidates for ultraviolet photocatalyst.

Powder X-ray diffraction patterns for three forms of MIL-53(Al), a metal organic framework (MOF) compound with breathing characteristics, were investigated using the Rietveld refinement method. These three samples are referred to as the MIL-53(Al)as-syn(the as synthesized sample), orthorhombic, Pnma, a= 17.064(2) Å, b= 6.6069(9) Å, c= 12.1636(13) Å, V= 1371.3(2) Å3, Z= 4), MIL-53(Al)LT-H(low-temperature hydrated phase, monoclinic P21/c, a= 19.4993(8) Å, b= 15.2347(6) Å, c= 6.5687(3) Å, β= 104.219(4) °, V= 1891.55(10) Å3, Z= 8), and MIL-53(Al)HT-D(high-temperature dehydrated phase, Imma, a= 6.6324(5) Å, b= 16.736(2) Å, c= 12.840(2), V= 1425.2(2) Å3, Z= 4). The crystal structures of the “as-syn” sample and the HT-D sample are confirmed to be the commonly adopted ones. However, the structure of the MIL-53(Al)LT-Hphase is confirmed to be monoclinic with a space group of P21/cinstead of the commonly accepted space group Cc, resulting in a cell volume double in size. The structure has two slightly different types of channel. The pore volumes and pore surface area were estimated to be 0.11766 (8) cm3/g and 1461.3(10) m2/g for MIL-53(Al)HT-D(high-temperature dehydrated phase), and 0.08628 (5) cm3/g and 1401.6 (10) m2/g for MIL-53(Al)as-synphases, respectively. The powder patterns for the MIL-53(Al)as-synand MIL-53(Al)HT-Dphases are reported in this paper.

Structural characterization and X-ray reference powder pattern determination have been conducted for the Co- and Zn-containing tridymite derivatives Ba(Co1−xZnx)SiO4(x= 0.2, 0.4, 0.6, 0.8). The bright blue series of Ba(Co1−xZnx)SiO4crystallized in the hexagonal P63space group (No. 173), with Z= 6. While the lattice parameter “a”decreases from 9.126 (2) Å to 9.10374(6) Å from x= 0.2 to 0.8, the lattice parameter “c”increases from 8.69477(12) Å to 8.72200(10) Å, respectively. Apparently, despite the similarity of ionic sizes of Zn2+and Co2+, these opposing trends are due to the framework tetrahedral tilting of (ZnCo)O4. The lattice volume, V, remains comparable between 626.27 Å3and 626.017 (7) Å3from x= 0 to x= 0.8. UV-visible absorption spectrum measurements indicate the band gap of these two materials to be ≈3.3 and ≈3.5 eV, respectively, therefore potential UV photocatalytic materials. Reference powder X-ray diffraction patterns of these compounds have been submitted to be included in the Powder Diffraction File (PDF).

A series of double-perovskite oxides, Sr2RNbO6(R= Sm, Gd, Dy, Ho, Y, Tm, and Lu) were prepared and their crystal structure and powder diffraction reference patterns were determined using the Rietveld analysis technique. The crystal structure of each of the Sr2RNbO6phase is reported in this paper. The R= Gd, Ho, and Lu samples were studied using synchrotron radiation, while R= Sm, Dy, Y, and Tm samples were studied using laboratory X-ray diffraction. Members of Sr2RNbO6are monoclinic with a space group of P21/nand are isostructural with each other. Following the trend of “lanthanide contraction”, from R= Sm to Lu, the lattice parameters “a” of these compounds decreases from 5.84672(10) to 5.78100(3) Å, bfrom 5.93192(13) to 5.80977(3) Å, cfrom 8.3142(2) to 8.18957(5) Å, and Vdecreases from 288.355(11) to 275.057(2) Å3. In this double-perovskite series, the R3+and Nb5+ions are structurally ordered. The average Nb–O bond length is nearly constant, while the average R–O bond length decreases with the decreasing ionic radius of R3+. Powder diffraction patterns for these compounds have been submitted to the Powder Diffraction File (PDF).

The crystal structure and powder patterns were prepared for the distorted perovskite series R(Co3/4Ti1/4)O3(R= La, Pr, Nd, Sm, Eu, Gd, Dy, Ho). The R(Co3/4Ti1/4)O3members are isostructural with each other and are crystallized in the orthorhombic crystal system with space group Pnma, Z= 4. From R= La to Ho, the lattice parameters arange from 5.4614(3) to 5.5368(2) Å, brange from 7.7442(4) to 7.4859(2) Å, and crange from 5.5046(3) to 5.2170(2) Å. The unit-cell volumes, Vwhich range from 232.81(2) to 216.237(11) Å3follow the trend of “lanthanide contraction”. The structure distortion of these compounds is evidenced in the tilt angles θ, ϕ, and ω, which represent rotations of an octahedron about the pseudo-cubic perovskite [110]p, [001]pand [111]paxes. All three tilt angles increase across the lanthanide series (for R= La to R= Ho: θincreases from 8.34° to 17.00°, ϕfrom 6.24° to 8.53°, and ωfrom 10.41° to 18.96°), indicating a greater octahedral distortion as the ionic radius of R3+[r(R3+)] decreases. The bond valence sum values for the (Co/Ti) site and the Rsite of R(Co3/4Ti1/4)O3reveal no significant bond strain in these compounds. X-ray diffraction patterns of the R(Co3/4Ti1/4)O3samples were submitted to the Powder Diffraction File.

X-ray reference powder patterns and structures have been determined for a series of cobalt-, nickel- and zinc-containing niobates, Co(NixZn1-x)Nb4O12(x= 0.2, 0.4, 0.6, 0.8). The Co(NixZn1-x)Nb4O12series crystallize in the space group of Pbcn, which is of the disordered columbite-type structure (a-PbO2). The lattice parameters range from a= 14.11190(13) to 14.1569(3) Å, b= 5.69965(6) to 5.71209(13) Å, c= 5.03332(5) to 5.03673(11) Å, and V= 404.844(8) to 407.296(17) Å3from x= 0.8 to 0.2, respectively. Co(NixZn1-x)Nb4O12contains double zig-zag chains of NbO6octahedra and single chain of (Ni,Zn,Co)O6octahedra run parallel to the bc-plane. Within the same chain the NbO6octahedra share edges, while the adjacent NbO6chains are joined to each other through common oxygen corners. These double NbO6chains are further linked together along the [100]-direction through another (Co,Ni,Zn)O6units, via common oxygen corners. The edge-sharing (Co,Ni,Zn)O6also forms zig-zag chains along the c-axis. Powder X-ray diffraction patterns of this series of compounds have been submitted to be included in the Powder Diffraction File.

The structure of a series of lanthanide iron cobalt perovskite oxides, R(Fe0.5Co0.5)O3(R= Pr, Nd, Sm, Eu, and Gd), have been investigated. The space group of these compounds was confirmed to be orthorhombic Pnma(No. 62), Z= 4. From Pr to Gd, the lattice parameter avaries from 5.466 35(13) Å to 5.507 10(13) Å, bfrom 7.7018(2) to 7.561 75(13) Å, cfrom 5.443 38(10) to 5.292 00(8) Å, and unit-cell volume Vfrom 229.170(9) Å3to 220.376(9) Å3, respectively. While the trend of Vfollows the trend of the lanthanide contraction, the lattice parameter “a” increases as the ionic radius r(R3+) decreases. X-ray diffraction (XRD) and transmission electron microscopy confirm that Fe and Co are disordered over the octahedral sites. The structure distortion of these compounds is evidenced in the tilt angles ?, ?, and ?, which represent rotations of an octahedron about the pseudocubic perovskite [110]p, [001]p, and [111]paxes. All three tilt angles increase across the lanthanide series (for R= Pr to R= Gd: ?increases from 12.3° to 15.2°, ?from 7.5° to 15.8°, and ?from 14.4° to 21.7°), indicating a greater octahedral distortion as r(R3+) decreases. The bond valence sum for the sixfold (Fe/Co) site and the eightfold Rsite of R(Fe0.5Co0.5)O3reveal no significant bond strain. Density Functional Theory calculations for Pr(Fe0.5Co0.5)O3support the disorder of Fe and Co and suggest that this compound to be a narrow band gap semiconductor. XRD patterns of the R(Fe0.5Co0.5)O3samples were submitted to the Powder Diffraction File.

The structures and powder X-ray reference diffraction patterns of the “natural superlattice” series Bi1-xPbxOCuSe (x= 0, 0.02, 0.04, 0.06, 0.08, and 0.10) have been investigated. As the ionic radius of Pb2+is greater than that of Bi3+, the unit-cell volume of Bi1-xPbxOCuSe increases progressively from x= 0 to 0.1, namely, from 137.868(5) to 139.172(11) Å3, as expected. The structure of Bi1-xPbxOCuSe is built from [Bi2(1-x)Pb2xO2]2(1-x)+layers normal to the c-axis alternating with [Cu2Se2]2(1-x)-fluorite-like layers. Pb substitution in the Bi site of Bi1-xPbxOCuSe leads to the weakening of the “bonding” between the [Bi2(1-x)Pb2xO2]2(1-x)+and the [Cu2Se2]2(1-x)-layers. Powder patterns of Bi1-xPbxOCuSe were submitted to be included in the Powder Diffraction File.

X-ray reference powder patterns and crystal structures have been determined for a series of titanium- and cobalt-containing layered alkaline-earth compounds with nominal formula (BaxSr1-x)Ti6Co6O19(x= 0.2, 0.4, 0.6, 0.8). Structural isomorphism of the title compounds with the hexagonal ferrite BaFe12O19and magnetoplumbite (PbFe12O19), was confirmed. The (BaxSr1-x)Ti6Co6O19series crystallize in the space group of P63/mmc(No. 194) and Z= 2. The lattice parameters range from a= 5.90729(6) Å, c= 23.2378(3) Å, and V= 702.27(2) Å3for x= 0.2 to a= 5.914 93(9), c= 23.3391(5) Å, and V= 707.15(2) Å3with x= 0.8. The structure consists of alternating spinel S-block and R-blocks. The tetrahedral sites within the spinel S-blocks are occupied with only Co2+, while Ti4+is mainly located in the octahedral sites of the spinel S-blocks and in the face-sharing octahedral site of the R-blocks. A bipyramidal mixed Co/Ti site was confirmed in the R-block of the structure. Powder X-ray diffraction patterns of this series of compounds have been submitted to be included in the Powder Diffraction File.

X-ray structural characterization and X-ray reference powder patterns have been determined for two series of iron- and cobalt-containing layered compounds (BaxSr1-x)2Co2Fe12O22(x= 0.2, 0.4, 0.6, 0.8) and (BaxSr1-x)Co2Fe16O27(x= 0.2, 0.4, 0.6, 0.8). The (BaxSr1-x)2Co2Fe12O22series of compounds crystallized in the space group R$\bar 3$m(No. 166), with Z= 3. The structure is essentially that of the Y-type hexagonal ferrite, BaM2+Fe63+O11. The lattice parameters range from a= 5.859 15(8) to 5.843 72(8) Å, and c= 43.4975(9) to 43.3516(9) Å for x= 0.2 to 0.8, respectively. The (BaxSr1-x)Co2Fe16O27series (W-type hexagonal ferrite) crystallized in the space group P63/mmc(No. 194) and Z= 2. The lattice parameters range from a= 5.902 05(12) to 5.8979(2) Å and c= 32.9002(10) to 32.8110(13) Å for x= 0.2 to 0.8. Results of measurements of the Seebeck coefficient and resistivity of these two sets of samples indicated that they are insulators. Powder X-ray diffraction patterns of these two series of compounds have been submitted to be included in the Powder Diffraction File.

Cu-paddle-wheel-based Cu3(BTC)2(nicknamed Cu-BTC, where BTC = benzene 1,3,5-tricarboxylate) is a metal organic framework (MOF) compound that adopts a zeolite-like topology. We have determined the pore-size distribution using the Gelb and Gubbins technique, the microstructure using small-angle neutron scattering and (ultra) small-angle X-ray scattering (USAXS\SAXS) techniques, and X-ray powder diffraction reference patterns for both dehydrated d-Cu-BTC [Cu3(C9H3O6)2] and hydrated h-Cu-BTC [Cu3(C9H3O6)2(H2O)6.96] using the Rietveld refinement technique. Both samples were confirmed to be cubic Fm$\bar 3$m(no. 225), with lattice parameters of a= 26.279 19(3) Å, V= 18 148.31(6) Å3for d-Cu-BTC, and a= 26.3103(11) Å, and V= 18 213(2) Å3for h-Cu-BTC. The structure of d-Cu-BTC contains three main pores of which the diameters are approximately, in decreasing order, 12.6, 10.6, and 5.0 Å. The free volume for d-Cu-BTC is approximately (71.85 ± 0.05)% of the total volume and is reduced to approximately (61.33 ± 0.03)% for the h-Cu-BTC structure. The d-Cu-BTC phase undergoes microstructural changes when exposed to moisture in air. The reference X-ray powder patterns for these two materials have been determined for inclusion in the Powder Diffraction File.

The X-ray diffraction powder patterns were prepared and the crystal structures were refined for the double-perovskite series of compounds, Sr2RSbO6(R= Pr, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, Tm, Yb, and Lu). We found the structures of the entire Sr2RSbO6series to be monoclinic with space group P21/n(no. 14), and Z= 2.From R= Lu to Pr, the lattice parameters “a” range from 5.7779(2) to 5.879 05(8) Å, “b” range from 5.7888(2) to 5.969 52(9) Å, “c” range from 8.1767(3) to 8.369 20(12) Å, “ß” range from 90.112(2)° to 90.313(1)°, and “V” range from 273.483(4) to 293.714(7) Å3. These lattice parameters follow the well-established trend of “lanthanide contraction”. The R3+and Sb5+ions are found to be fully ordered in the double-perovskite arrangement of alternating corner-sharing octahedra in a zigzag fashion. The SrO12, RO6, and SbO6cages are all found to have distorted coordination environments. Powder diffraction patterns of these compounds have been prepared, submitted, and published in the Powder Diffraction File.

The crystal structure and powder X-ray diffraction (XRD) patterns for three skutterudite samples, Fe(Sb2+xTe1-x), x= 0.05, 0.10, 0.20, have been determined. These compounds crystallize in the cubic space group $Im\bar 3$. Te was found to randomly substitute in the Sb site. Because of the fact the covalent radius of Sb is greater than that of Te, a trend of increasing lattice parameter has been observed as the xvalue in Fe(Sb2+xTe1-x) increases [cell parameters range from 9.10432(4) to 9.11120(3) Å for x= 0.0 to 0.2, respectively]. The Fe–Sb/Te bond distance also increases progressively [from 2.5358(4) to 2.5388(4) Å] as the Te content decreases. While average Sb/Te–Sb/Te distances in the four-membered rings are similar in these three compounds, the average Sb/Te–Sb/Te edge distances in the octahedral framework increase progressively from 3.5845(12) to 3.5900(13) Å. Reference XRD patterns of these three phases have been prepared to be included in the Powder Diffraction File (PDF).

The structure and X-ray patterns of two series of barium lanthanide cobaltates, namely, Ba4Sr2R2Co4O15(R= La, Nd, Sm, Eu, Gd, and Dy), and Ba5SrR2Co4O15(R= La, Nd, Sm, Eu, and Gd) have been determined. These compounds crystallize in the space group P63mc; the unit-cell parameters of Ba4Sr2R2Co4O15(Rfrom La to Dy) decrease from a= 11.6128(2) Å to 11. 5266(9) Å, c= 6.869 03(11) to 6. 7630(5) Å, and V= 802.23(3) Å3to 778.17(15) Å3, respectively. In the Ba5SrR2Co4O15series (R= La to Gd), the unit-cell parameters decrease from a= 11.735 44(14) Å to 11.619 79(12) Å, c= 6.942 89 (14) Å to 6.836 52(8) Å, and V= 828.08(3) Å3to 799.40(2) Å3. In the general structure of (Ba6-xSrx)R2Co4O15, there are four Co ions per formula unit occupying one CoO6octahedral and three CoO4tetrahedral units. Through corner-sharing of these polyhedra, a larger Co4O15unit is formed. Sr2+ions adopt both octahedral and 8-fold coordination environment. R3+ions adopt 8-fold coordination (mixed site with Sr), while the larger Ba2+ions assume both 10- and 11-fold coordination environments. The samples were found to be insulators. X-ray diffraction patterns of these samples have been determined and submitted to the Powder Diffraction File (PDF).

M2(dhtp)·nH2O (M= Mn, Co, Ni, Zn; dhtp = 2,5-dihydroxyterephthalate), known as MOF74, is a family of excellent sorbent materials for CO2that contains coordinatively unsaturated metal sites and a honeycomb-like structure featuring a broad one-dimensional channel. This paper describes the structural feature and provides reference X-ray powder diffraction patterns of these four isostructural compounds. The structures were determined using synchrotron diffraction data obtained at beam line 11-BM at the Advanced Photon Source (APS) in the Argonne National Laboratory. The samples were confirmed to be hexagonal R 3(No. 148). From M= Mn, Co, Ni, to Zn, the lattice parameter aof MOF74 ranges from 26.131 73(4) Å to 26.5738(2) Å, cfrom 6.651 97(5) to 6.808 83(8) Å, and Vranges from 3948.08 Å3to 4163.99 Å3, respectively. The four reference X-ray powder diffraction patterns have been submitted for inclusion in the Powder Diffraction File (PDF).

The crystal structure of type I clathrate Ba8Ni4Ge42has been determined using neutron powder diffraction, transmission electron microscopy (TEM, for possible superlattice), and extended X-ray absorption fine structure (EXAFS) measurements. Ba8Ni4Ge42is cubic with the space group Pmnand unit-cell parameter a =10.6769(2) Å (Dx= 5.988 g cm-3). The structure combines two different types of polyhedra: the dodecahedron (Ge20, 20-atom cage with 12 pentagonal faces) and the tetrakaidecahedron (Ge24, 24-atom cage with 12 pentagonal and 2 hexagonal faces). Each unit cell contains two Ge20dodecahedra and six Ge24tetrakaidecahedra. The Ge20dodecahedra are linked via the interstitial 6cpositions. The framework structure is formed by a tetrahedrally bounded network of Ge atoms, whereas Ba atoms reside inside the Ge20and Ge24cavities at the 2aand 6dcrystallographic positions, respectively. Ni atoms exclusively occupy the 6cpositions located on the hexagonal faces of the larger tetrakaidecahedra; no Ni atoms are found in the smaller dodecahedra that consist of pentagonal faces. A local structure study using EXAFS supports the coexistence of Ge and Ni on the 6csite. Electron diffraction in TEM reveals no detectable Ge/Ni ordering.

The family of zeolitic imidazolate framework (ZIF) compounds is efficient sorbent materials that can be used for catalytic, ion exchange, gas storage, and gas separation applications. A high-resolution reference X-ray powder diffraction pattern for one of the ZIF members, bis(2-methylimidazolyl)-zinc, C8H10N4Zn (commonly known as ZIF-8), was determined using synchrotron diffraction data obtained at the Advanced Photon Source (APS) in Argonne, IL. The sample was confirmed to be cubic I-43m, with a= 17.01162(6) ?, V= 4932.08 ?3, and Z= 12. The reference X-ray powder diffraction pattern has been submitted for inclusion in the Powder Diffraction File (PDF).

Two selected members of the homologous series An+2BBn?O3n+3(A=Sr and Ca; Band B?=Co) have been investigated for their crystal structures because of their potential applications as thermoelectric materials. A combined Rietveld refinement and spin-polarized magnetic geometry optimization technique was employed for the structural studies. Both the n=3 member, (Sr0.8Ca0.2)5Co4O12, and the n=4 member, Sr6Co5O15, have distorted hexagonal perovskite-related structures that possess one-dimensional cobalt oxide chains separated by alkaline-earth cations. The linear chains consist of one unit of CoO6trigonal prism alternating with nunits of CoO6octahedra. Crystal structures and reference powder X-ray diffraction patterns of (Sr0.8Ca0.2)5Co4O11[P3c1, a=9.4196(2) ?, c=19.9857(6) ?, V=825.83 ?3, and Dx=5.358 g/cm3] and Sr6Co5O15[R32, a=9.497 64(12) ?, c=12.3956(2) ?, V=968.34 ?3, and Dx=5.455 g/cm3] are reported.

This paper reports a reference X-ray powder diffraction pattern for a high-pressure phase, CaCo2O4, which has been reported recently to have a large Seebeck coefficient. The structure of CaCo2O4is orthorhombic with space group Pnma, a=8.789(2) ?, b=2.9006(7) ?, c=10.282(3) ?, V=262.43 ?3, and Dc=5.62 g/cm3. This phase crystallizes in the CaFe2O4-type structure and consists of an edge- and corner-shared CoO6octahedral network. The reference pattern has been submitted to the Powder Diffraction File (PDF).

This paper reports the results of crystallography and crystal chemistry investigation of the (Ba1?xSrx)Y2CuO5(?green phase?) solid solution series by X-ray powder diffraction (XPD) and neutron powder diffraction techniques. The single phase regions for (Ba1?xSrx)Y2CuO5were determined to be 0?x?0.3 for samples prepared at 810 ?C in 100 Pa pO2, and 0?x?0.7 for samples prepared at 930 ?C in air. All single phase (Ba1?xSrx)Y2CuO5samples are isostructural to BaY2CuO5and can be indexed using an orthorhombic cell with the space group Pnma. Lattice parameters, a,b,cand the cell volume, V, of the (Ba1?xSrx)Y2CuO5members decrease linearly with increasing Sr substitution (x) on the Ba site. The general structure of (Ba1?xSrx)Y2CuO5can be considered as having a three-dimensional interconnected network of [YO7],[(Ba,Sr)O11], and [CuO5] polyhedra. The copper ions are located inside distorted [CuO5] ?square? pyramids. These pyramids are connected by the [Y2O11] groups that are formed from two monocapped [YO7] trigonal prisms sharing a triangular face. The Ba2+ions are found to reside in distorted 11-fold coordinated cages. The oxygen sites are essentially fully occupied. XPD reference patterns of two members of the series, (Ba0.3Sr0.7)Y2CuO5and (Ba0.7Sr0.3)Y2CuO5, were prepared for inclusion in the powder diffraction file.

The X-ray Rietveld refinement technique was used to determine the structure and prepare X-ray powder reference patterns for the phases R2Cu9Ti12O36(R=Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, Tm, Yb, and Lu). R2Cu9Ti12O36belongs to the perovskite-related [AC3](B4)O12family of structures, which are cubic with space group Im3. The lattice parameters of the R2Cu9Ti12O36series range from a=7.377 57(2) ?, V=401.550(3) ?3for R=Lu to a=7.399 87(3) ?, and V=405.202(4) ?3for R=Nd. The trend of these lattice parameters parallels the ?lanthanide contraction.? In the structure, R occupies the larger icosahedral Asite of the ideal ABO3perovskite structure, while Ti occupies the distorted octahedral Bsite. The Jahn-Teller cation Cu occupies the Csite. The twelve oxygens surrounding Cu are arranged as three mutually perpendicular rectangles of different size. The smallest and largest rectangles are nearly squares. One-third of the R site is vacant, and the chemical formula can be written as [R2?3X1?3Cu3](Ti4)O12, where X=vacancy. The X-ray powder patterns of R2Cu2Ti12O36have been submitted to ICDD for inclusion in the Powder Diffraction File (PDF).

The structure of BaSrR4O8(where R=La, Nd, Sm, Gd, Eu, Dy, Ho, Y, Er, Tm, Yb, and Lu) has been investigated, and the X-ray reference patterns of these compounds have been prepared using the Rietveld refinement technique. BaSrR2O4are isostructural to BaR2O4, which have the CaFe2O4structure type (orthorhombic, Pnam). The cell parameters of these compounds (R=Lu to La) range from 10.125 04(10) to 10.5501(8) ? for a, 3.362 49(3) to 3.692 04(24) ? for b, 11.846 91(13) to 12.5663(9) ? for c, and 403.33 to 489.47 ?3for V, respectively. There is a linear relationship between Vand the Shannon ionic radius of R. Unlike the BaR2O4compositions (R=Tm, Lu, and Yb), which produced a mixture of Ba3R4O9and unreacted lanthanide oxides, single-phase BaSrTm4O8, BaSrLu4O8, and BaSrYb4O8were successfully prepared.

The structure of the Ba5R8Zn4O21series (R=lanthanides) was investigated using X-ray Rietveld refinements. The compounds were successfully prepared for R=Eu, Gd, Dy, Ho, Er, Tm, and Yb. Ba5R8Zn4O21crystallizes in the tetragonal space group I4/m; for R=Yb to Eu, aranges from 13.635 02(5) to 13.960 62(9) ?, cfrom 5.658 46(3) to 5.784 83(5) ?, and Vfrom 1051.987(8) to 1127.459(14) ?3. The Zn2+ions adopt a fivefold distorted square pyramidal coordination. The seven-coordinate R3+reside in monocapped trigonal prisms. These prisms share edges, and form layers stacked along the caxis. There are two types of BaO polyhedra: bicapped square prisms (BaO10), and irregular BaO10polyhedra. For larger R, Ba5R8Zn4O21was not stable, and tetragonal BaR2ZnO5(La, Nd) and orthorhombic BaR2ZnO5(Sm) phases were observed instead.

The crystal structure of the low-temperature oxidized form of Sr49.5Ca16.5Bi34O151has been determined using a combination of neutron, synchrotron, and laboratory X-ray powder diffraction data. The structure is pseudo-orthorhombic; systematic absences and successful refinement indicated the true structure to be monoclinic, with space group P2l/n. Structural refinement using only neutron powder data yielded the lattice parameters a=8.38 898(29) ?, b=5.99 334(21) ?, c=5.89 586(20) ?, ?=89.997(8)?, and V=296.43(3) ?3. This compound is a distorted perovskite phase [described in the perovskite ABO3formula as Sr(Bi0.7Ca0.3)O3] with ordering of the M-site cations, resulting in the formula A2MM?O6. In this ordered structure, the Asites are solely occupied by Sr, the Msites mainly by Bi, while on the M?sites Bi and Ca are distributed in an approximate ratio of 2:3. The MO6and M?O6octahedra share corners, and are tilted with respect to the neighboring layers with an angle of ?15? around all three axes. The tilt system symbol is a+a?a?according to Glazer notation. All Bi ions are in the 5+oxidation state.

The structures of the solid solution series (Sr4??Ca?)PtO6, with ?=0, 0.85(1), 2, and 3, have been investigated using the Rietveld refinement technique with laboratory X-ray powder diffraction data. A complete solid solution between Sr and Ca was confirmed to exist. These compounds crystallize in the rhombohedral space group R3?c. The cell parameters of the series range from aof 9.4780(3) to 9.7477(1) ?, and cfrom 11.3301(4) to 11.8791(1) ? for ? from 3 to 0, respectively. The structure consists of chains of alternating trigonal prismatic (Sr, Ca)O6and octahedral PtO6units running parallel to the caxis. These chains are connected to each other via a second type of (Sr, Ca) ions, which are surrounded by eight oxygens, in a distorted square antiprismatic geometry. As Ca replaced Sr in Sr4PtO6, it was found to substitute preferentially in the smaller octahedral (Sr, Ca)1 site (6a) rather than at the eight-coordinate (Sr, Ca)2 site (18e). There appears to be an anomaly of cell parameters aand cat the compound Sr3.15Ca0.85PtO6. Their dependence on Ca content changes at ??1.00, where the Ca has fully replaced Sr in the 6asite. The substitution of Sr by Ca reduced the average (Sr, Ca)1?O length from 2.411 to 2.311 ? and (Sr, Ca)2?O from 2.659 to 2.570 ? as the composition varied from Sr4PtO6to SrCa3PtO6. Reference X-ray powder diffraction patterns were prepared from the Rietveld refinement results for these members of the solid solution series. Magnetic susceptibility measurements of three of the samples (?=0, 0.85, 2) show electronic transitions at low temperatures.

The crystal structure of the solid solution alkaline earth plumbate phase Sr4?xCaxPb2O8was investigated using the X-ray Rietveld technique for x=1, 2, and 3. The lattice parameters a, b, c, and Vwere found to decrease linearly as the Sr at site 4hwas replaced by Ca. The structure features chains of edge-sharing PbO6octahedra, linked by seven-coordinated (Ca/Sr)?O monocapped trigonal prisms. The structure is similar to that of Pb3O4, which can be reformulated as Pb2IIPbIVO4. X-ray diffraction patterns for the solid solution members SrCa3Pb2O8, Sr2Ca2Pb2O8, and Sr3CaPb2O8were prepared for inclusion in the Powder Diffraction File.

The crystal structure of Ba4Ti10Al2O27has been refined in a joint Rietveld refinement using neutron and X-ray powder data. The compound crystallizes in the monoclinic space group C2/m, with a=19.7057(3), b=11.3575(2), c=9.8318(2) ?, ?=109.218(1)?, and V=2077.81(5) ?3. It is isostructural to Ba4Ti10Fe2O27and Ba4Ti11ZnO27, and consists of a complex network of corner- and edge-sharing Ti/Al octahedra. The structure can best be described based on close-packed O/Ba-O layers in an 8-layer (8L) chhcchhcsequence. Out of a total of ten Ti/Al sites, Al was found to substitute for Ti mainly in four sites, and the remaining six sites were predominantly occupied by Ti. The unit cell contents derived from the refined site occupancies are Ba16Ti40.48Al7.52O108, essentially identical to the expected Ba16Ti40Al8O108. A reference diffraction pattern of this phase is also reported.

Calculated patterns for the BaR2PdO5series, in which Xis Pd and R=Nd, Sm, Eu, or Gd, have been prepared for materials characterization until experimental patterns can be determined. These compounds are isostructural to the superconductor related ?brown phases? BaLa2CuO5and BaNd2CuO5, which are tetragonal with space group P4/mbm, Z=4. The cell parameters of the Eu and Gd compounds were derived from the La and Nd analogs. The calculated patterns of these four compounds compared well to an experimental pattern of BaNd2CuO5.

Reaction of tungsten (W) with SF6has been studied using two types of samples. The first type (type I) consisted of rods fabricated by a drawing process and the second type (type II) consisted of square plates cut from a hot pressed billet. After the corrosion experiments, scanning electron microscopy (SEM) examination of the type I sample indicated the presence of deep pits parallel to the rod axis. X-ray analysis of these rods showed preferred orientation. Pole figure measurement was subsequently conducted to quantify the preferred orientation by using neutron diffraction. A significant orientation effect on the corrosion process was found, possibly originating from the considerable granular elongation parallel with the rod axis produced during the fabrication process. In contrast, the type II sample showed no directional corrosion and insignificant preferred orientation.

AbstractThe superconductor related phases Ba3R3Cu6O14+x(or Ba2?zR1+zCu3O7+x, with z=0.5), where R = Pr, Nd, Sm, and Eu, have been prepared and characterized by X-ray powder diffraction, ac magnetic susceptibility measurement, resistivity measurement and thermogravimetric analysis (TGA). Attempts to make corresponding compounds with R = Gd, Dy, Y, Er, and Lu were not successful; they do not appear to form for rare-earth elements, R, with an ionic size smaller than Eu. The oxygen content of the successful materials was estimated by TGA. The Ba3R3Cu6Cu14+xcompounds which were sintered at 950?C and annealed in oxygen at 550?C were found to be nonsuperconducting above 10K. Previously reported results for the R=La compound have indicated that it was superconducting with a transition temperature of 15K The oxidation-reduction behavior of the Ba3R3Cu6O14+xmaterials is similar to that of the superconductor phases Ba2RCu3O6+x.These present isostructural compounds are tetragonal with a space group of P4/mmm. The cell parameters range from a = 3.8612(4), c = 11.5624(14) ?, V = 172.38(4) ?3in the Eu compound to a = 3.8893(3), c = 11.6370(11) ?, and V = 176.03(3) ?3in the Pr compound. The standard X-ray diffraction patterns of these materials are given.

AbstractA series of BaO:RxOy:CuO materials has been prepared where R=Y, La, Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. They have been characterized by X-ray powder diffraction methods. All BaR2CuO5phases, commonly referred to as the ?green phases?, are orthorhombic with space group Pbnm(62) and are isostructural. These single phase materials could be prepared with most lanthanides, except for La, Ce, Pr, Nd and Tb. Possible reasons for the exceptions are discussed. Both La and Nd tend to form a brown solid solution of Ba2+2xR4-2xCu2-xO10-2xwith a tetragonal space group of P4/mbm(127). The major phases found in the Ce, Pr and Tb compositions are the perovskite-related structures BaRO3, and in the Pr case, Ba2PrCu3O6+xas well. The cell parameters of the green phase materials increase progressively from the Lu compound to the Sm compound: aranges from 7.0506(6) to 7.2754(4) ?, bfrom 12. 0534(8) to 12. 4029(7) ?, cfrom 5.6099(5) to 5. 7602(3) ?, and the cell volume from 476.75(6) to 519.78(4) ?3. A correlation of the crystallographic data with the size of the R elements is given.

AbstractExternal standard and internal standard calibrations are important procedures for achieving high accuracy in X-ray powder diffraction studies. The theoretical basis as well as procedures for obtaining calibration curves are given. Methods and examples of selecting Standard Reference Materials (SRMs) which are produced and issued by the National Bureau of Standards (NBS), and procedures of sample preparation with these standards are also described. Three examples are presented to indicate the value of using SRMs.

The activity of the high Tctask group of the ICDD Ceramic Subcommittee is described. This activity includes the compilation of X-ray powder diffraction patterns of the high Tcsuperconductors and related phases identified from the International Centre for Diffraction Data/Powder Diffraction File (ICDD/PDF). The coverage of this ICDD/PDF Superconductor SubFile (SC) includes high Tcphases and their structurally related phases, products of elemental substitution in the high Tcphases, phases found in the phase diagrams containing the high Tcphases, as well as potential reaction products with commonly used sample containers, and potential conventional low-temperature (metallic and nonmetallic) superconductors.

Reference X-ray diffraction patterns for the quarternary intermetallic superconductor phases of compositions LuNi2B2C and YNi2B2C are reported. Both materials were synthesized by the arc-melting technique. The patterns of these metallic phases exhibit preferred orientation in an ordinarily pressed sample, which was minimized through special specimen preparation. The observed intensities and the calculated values for both phases agree reasonably well with each other. Both compounds were refined in the space group I4/mmm, with a=3.4647(1) ? and c=10.6330(4) ? for LuNi2B2C and a=3.5271(1) ?, c=10.5361(7) ? for YNi2B2C.

AbstractThe compounds BaR2O4, where R = La, Nd, Sm, Gd, Eu, Dy, Ho and Er have been prepared from a stoichiometric mixture of BaCO3and lanthanide oxides, and characterized by X-ray powder diffraction. Standard X-ray patterns of these phases were prepared. In general, BaR2O4crystallizes in the pervoskite-related CaFe2O4structure which is orthorhombic with a space group Pnam. The cell parameters of these compounds from R = Er to La range from 10.3729(12) to 10.668(2) ? for a, 12.0699(11) to 12.642(2) ? for b, from 3.4356(4) to 3.7037(10) ? for c, and from 450.14(5) ?3to 499.51 ?3for V respectively. A monotonic, linear relationship is obtained when V is plotted against the cube of the ionic radius of R. When R = Tm, Lu and Yb, the BaO?R2O3composition produced the mixture Ba3R4O9and the unreacted lanthanide oxide. Under the present experimental conditions, the compound BaRO3was the predominant component when R = Ce, Pr, and Tb.