New layered bismuth oxides Bi2(BiCaNa)m−1NbmO3m+3(m=2-4) with the Aurivillius type phase were successfully synthesized. The structures of the compounds have been studied by X-ray powder diffraction and refined by the Rietveld method. Bi2.25Ca0.5Na0.25Nb2O9(m=2) has an orthorhombic crystal structure with lattice constants a=5.4478(1) Å;b=5.4770(2) Å;c=24.883(8) Å, space group A21am (No. 36). Bi2CaNaNb3O12 and Bi2.25Ca0.5Na1.25Nb3O12(m=3) are orthorhombic with Fmmm(No. 69) space group and the unit-cell parameters a=5.4473(7) Å, b=5.4770(3) Å, c=32.722(6) Å and a=5.4574(7) Å, b=5.4884 (3) Å, c=32.711(6) Å, respectively. The structure of Bi2CaNa2Nb4O15(m=4) was found to be orthorhombic with parameters a=5.4584(8) Å, b=5.4833(3) Å, c=40.534(1) Å and was refined in the space group A21am (No. 36).

The crystal structure of the perovskite phase KCaF3 has been redetermined at 4.2 and 300 K using powder neutron diffraction collected at the highest resolution. At both temperatures the phase was found to be orthorhombic in space group Pnma, with lattice parameters a=0.622 879(5) nm, b=0.870 031(7) nm, c=0.611 210(5) nm at 4.2 K, and a=0.621 488(6) nm, b=0.876 360(8) nm, c=0.616 481(6) nm at 300 K. The CaF6 octahedron is regular at both temperatures with octahedral rotations of 9.6° and 13.2° for the in-phase and anti-phase tilts, respectively, at 4.2 K. No evidence was found to support the recent revision of the space group from Pnma to the monoclinic space group B21∕m.

The measurement of lattice parameters using the Le Bail method was shown to be inappropriate for a complex, low symmetry, structure, even with high resolution synchrotron diffraction data. The method failed as a result of ambiguous indexing in the absence of constraints on diffraction intensities, that arise when a structural model is used, combined with the large number of reflections. A caution for the use of the Le Bail and other whole-powder pattern decomposition methods is presented, particularly for high reflection density data.

The ternary nitridotungstate Li6WN4 has been synthesized via the solid state reaction of lithium subnitride, Li3N, with W under nitrogen. High quality X-ray powder diffraction data were collected for the crystal-structure determination. Li6WN4 crystallizes in the tetragonal system, space group P42∕nmc, with cell parameters a=6.6759(3) Å and c=4.9280(3) Å, Z=2. Preliminary thermal stability measurements of Li6WN4 show that it is sensitive to moisture, even at room temperature, and decomposes at high temperatures below 1000 °C under flowing nitrogen.

Single-phase (Ho0.50Ca0.50)MnO3 has been successfully prepared by means of solid state reaction at high temperature. Its crystal structure, as well as those of Cr-doped samples(Ho1−xCax)(Mn1−yCry)O3, has been refined by the Rietveld method, using X-ray powder diffraction data. All the examined compounds crystallize in the Pnma space group with a distorted perovskite-type structure. The distortion of the BO6 octahedra, due to the Jahn–Teller Mn3+ ionic species, decreases with the Cr content. Bond valence sum calculations were carried out using the refined results.

Ferrous nitroprusside can be obtained in three structural modifications: two different unstable phases, monoclinic trihydrate and cubic pentahydrate, and the stable one, an orthorhombic dihydrate. This contribution reports the crystal structure of the last one. Cell parameters are: a=13.9734 (2), b=7.4274 (1), and c=10.4697 (1) Å; with four formula units per cell (Z=4). The crystal structure was refined from the corresponding XRD powder pattern using the Rietveld method. Final agreement factors of the refinement process were Rwp=8.46, Rp=6.54, and S=1.38. The crystal structure is formed by a tridimensional assembling of the [Fe(CN)5NO] molecular block through iron atoms bounded at the N end of the CN ligands. The NO group remains unlinked at its O atom. The octahedral coordination of the assembling metal is completed with a coordinated water molecule which stabilizes a second water through a strong hydrogen bond interaction. The tridimensional structure appears as piled up rippled sheets leading to a system of interconnected small cavities which increase their available volume on the material dehydration. This complex loses its crystal water below 100 °C and then remains stable up to above 160 °C when the decomposition process begins with the loss of the NO ligand.

Crystal structures of A0.50SbFe(PO4)3(A=Mn, Cd) phases, obtained by solid state reaction at 920 °C, were determined at room temperature from X-ray powder diffraction (XRD) using the Rietveld method. The structures of the two samples are of the Nasicon-type with the R3 space group. Hexagonal cell parameters for A=Mn and Cd are: a=8.375(1) Å, c=21.597(2) Å and a=8.313(1) Å, c=21.996(2) Å, respectively. From XRD data, it is difficult to unambiguously distinguish between Cd2+ and Sb5+ ions in Cd0.50SbFe(PO4)3 and between Mn2+ and Fe3+ cations in Mn0.50SbFe(PO4)3. Nevertheless the overall set of cation–anion distances within the Nasicon framework clearly shows that the cation distribution can be illustrated by the {[A0.50]3a[◻0.50]3b}M1SbFe(PO4)3 (A=Mn, Cd) crystallographic formula. The divalent A2+ cations and vacancies are ordered within the two positions, 3a and 3b, of the M1 sites. Structure refinements show also a quasi-ordered distribution of Sb5+ and Fe3+ ions within the Nasicon framework. Thus, each A(3a)O6(A=Mn, Cd) octahedron shares two faces with two Fe3+O6 octahedra and each vacancy (◻(3b)O6) site is located between two Sb5+O6 octahedra.

Europium nitride (EuN), which is potentially used as an activator for nitride luminescent materials, was prepared by direct nitridation at 600 °C in a NH3 atmosphere. X-ray powder diffraction and composition analysis of the nitrided sample were carefully conducted under an oxygen-free environment. The nitrided sample was found to be mononitride with NaCl structure. An appreciable amount of oxygen (∼0.06 a.u.) was detected, but no secondary oxide phase was found. The results suggest oxygen dissolution into the lattice of EuN.

X-ray powder diffraction data are presented for nine new phases with the tetragonal tungsten bronze structure. By comparison with the structure of the M=Nb,RE=La analogue, these contain Ba in the large pentagonal sites with coordination number 15, a range of large rare-earth cations and Bi in the twelve coordinate sites, and the smaller cations, Ti and either Nb or Ta, in the octahedral framework sites. The a lattice parameter data of the tetragonal unit cell show an approximately linear variation with trivalent ion radius, apart from Dy, whose value appears to be anomalous; data for c show little variation with trivalent ion radius.

Powder diffraction data for five three-layer Aurivillius ceramics of the form Bi2Sr2−xAxNb2TiO12 (A=Ca,Ba,x=0,0.5,1) have been determined from specimens that were characterized using both X-ray and neutron diffraction. Full Rietveld analysis demonstrated that the crystals were all tetragonal (space group I4∕mmm, #139), with highly aniostropic layered structures with lattice parameters on the order of a=3.9 Å and c=33 Å, and densities on the order of 7 g∕cm3

X-ray powder diffraction data for the high temperature phase of NaBi3V2O10 obtained from in situ high temperature XRD studies are presented. NaBi3V2O10 undergoes a phase transition from triclinic to monoclinic at about 600 °C. The unit cell parameters of the high temperature monoclinic phase at 600 °C are: a=12.3899(21), b=5.5642(10), c=7.1543(18) Å and β=98.393(16)°, V=487.94(13) Å3 and Z=2, ρcal=6.20 g∕cc. On further increasing the temperature, it partially decomposes to a γ-Bi4V2O11 type phase. The details of this phase as well as the stability of NaBi3V2O10 are discussed.

The diosgenin, (25R)-spirost-5-en-3β-ol, was isolated from rhizomes of dioscorea meridensis and characterized by X-ray powder diffraction, IR and MS. The diosgenin was found to be monoclinic, with refined unit cell parameters a=16.774(3), b=7.259(2), c=10.383(2) Å, β=92.74(2)°, V=1262.9(3) (Å3), Z=2, Dx(g∕cm−3)1.089, with space group P21 (No. 4).

Complexes of 1,8-bis(dimethylamino)naphthalene, known also as DMAN, with phthalic acid, terephthalic acid, and 5-aminoisophthalic acid were synthesized and investigated by means of powder diffraction methods. DMAN and phthalic acid complexes crystallize in the orthorhombic system, space group Pnmm (59) with the lattice parameters a=1.17423(3) nm, b=1.7124(4) nm, c=0.9933(4) nm, V=1.997 24 nm3, whereas DMAN complexes with terephthalic acid or 5-aminoisophthalic acid crystallize in the monoclinic system in the space group P2 or P2∕m with the lattice parameters a=2.4337(5) nm, b=0.9665(2) nm, c=1.1800(3) nm, β=91.53(2)°, V=2.774 51 nm3 and a=2.1609(7) nm, b=1.1017(6) nm, c=1.8921(7) nm, β=112.095(34)°, V=4.173 46 nm3, respectively.

X-ray diffraction investigations of two phenol derivatives - 2,2′-Thiobis(4-methyl-6-tert-butylphenol) and 2,2′-Methylenebis(4-methyl-6-tert-butylphenol) were carried out. Both compounds at room temperature have similar cell volume and the same number of molecules in an unit cell. However, 2,2′-Thiobis(4-methyl-6-tert-butylphenol) crystallizes in the monoclinic system with unit cell parameters refined to a=0.8278(2) nm, b=1.2968(4) nm, c=1.9493(7) nm, β=90.93(2)°, space group P21∕n(14), whereas 2,2′-Methylenebis(4-methyl-6-tert-butylphenol) crystallizes in the orthorhombic system with unit cell parameters refined to a=1.6203(5) nm, b=1.2827(5) nm, c=1.0197(3) nm, space group Pna21(33). The investigated C22H30O2S turned out to be a new polymorph of 2,2′-Thiobis(4-methyl-6-tert-butylphenol).