Showing papers in "Crystallography Reports in 2019"

Investigation of the Structure of Crystal-Forming Solutions of Potassium Dihydrogen Phosphate K(H 2 PO 4 ) (KDP type) on the Basis of Modeling Precursor Clusters and According to Small-Angle X-Ray Scattering Data

Abstract: The potassium dihydrogen phosphate K(H2PO4) (KDP) cluster structures formed in aqueous solutions have been theoretically and experimentally investigated. Cluster modeling of the self-assembly of supramolecular KDP structures is performed, and oligomer clusters (dimers, tetramers, and octamers) are determined. Oligomer clusters are found for the first time in saturated KDP aqueous solutions in the temperature range of 5–80°С by small-angle X-ray scattering; their oligomeric composition is quantitatively estimated. It is shown that potassium dihydrogen phosphate exists in the form of dimers in a supersaturated solution in a wide temperature range, and only sharp cooling leads to the occurrence of other clusters: first tetramers and then octamers; the latter are presumably primary chains of the KDP crystal structure. The distance between tetramer centers corresponds to the translation period c = 6.906 A.

X-ray Diffraction Analysis and Electron Microscopy of the Carbon Fiber Structure

Abstract: A technique for studying the carbon-fiber structure using X-ray diffraction and electron microscopy has been developed. Average crystal-structure parameters are determined for samples of commercial polyacrylonitrile carbon fibers by X-ray diffractometry. Electron microscopy study has confirmed the diffraction data and provided data on the fiber macrostructure. A comparative analysis of the structures and quality of the samples under study has been performed based on the results obtained.

The Yttrium, Lanthanum, and Lanthanide Trifluorides: Internal Periodicity of Phase Transitions

Abstract: Internal periodicity of phase transitions (fusion and polymorphism) has been revealed in trifluorides of Y, La, and 14 lanthanides. This periodicity is determined by the internal periodicity of filling of the 4f-electron subshell of rare-earth elements (REEs, R), in which cerium 58Се–64Gd and terbium 65Тb–71Lu subsets can be selected. The lanthanide compression of ionic radii R3+ (15% towards the smaller one) induces the formation of three structure types: LaF3, β-YF3, and α-YF3 (α-UO3). The formula volumes Vform of REE trifluorides of the LaF3 and β-YF3 structure types only partially obey the internal periodicity of lanthanides with an increase in Z. The internal periodicity of the fusion and polymorphism of REE trifluorides (without ScF3) divides RF3 into four structural subgroups: A (R = La–Nd), B (R = Pm–Gd), C (R = Tb–Ho), and D (R = Er–Lu, Y), strictly specifying the percentage and elemental composition of each subgroup. The periodicity of the RF3 polymorphism in the products manifests itself in the crystallization of the melts prone to supercooling in the form of a periodic change of single crystals with coarse- or fine-grained blocks of the low-temperature forms.

Oxophosphoryl Complexes of Dipyrrin: Spectral and Aggregation Characteristics of Solutions and Thin Films

Abstract: The spectral characteristics of a compound representing a new class of organic luminescent materials—dipyrrin oxophosphoryl complex (PODIPY)—in organic solvents and thin films have been investigated. The compound under study exhibits high-intensity fluorescence in solutions, which is preserved when passing to thin films obtained by layer-by-layer deposition onto a substrate using the Langmuir–Schaeffer technique. PODIPY is characterized by has bright solvatochromic fluorescence, which is related to the redistribution of the intensities of absorption and fluorescence bands and their shift. This effect originates from the specific solvation of PODIPY with partition of the oxygen atoms of oxophosphoryl group. A transition from solutions to films and an increase in the number of transfers lead to the fluorescence quenching without the formation of G aggregates in the film.

A Minimal Generating Set of Intermediate-Symmetry Fedorov Groups

Abstract: Minimization of generating sets (sets of generators) indicated in the International Tables for Crystallography has been performed for tetragonal, trigonal, and hexagonal space groups. It is established that generating sets of some groups cannot be minimized to a set of minimally possible power (minimal set) for a given group, which suggests that the generating set used in the International Tables for Crystallography should be improved.

Skeletal Sublattices of Heavy Components As a Basis of Stability of Crystal Structures

Abstract: A crystallographic structural analysis of low- and high-temperature phases of BaSi2O5 and Na3SO4F compounds has been carried out in order to confirm the thesis that the stability of natural-abundant structural types is mainly determined by the configuration of the heaviest components. The geometry of cation (skeletal) sublattices is presented; it is shown that they play a key role in the formation of structures and are relatively stable at temperature phase transitions.

Study of the Influence of a Precipitant Cation on the Formation of Oligomers in Crystallization Solutions of Lysozyme Protein

Abstract: The influence of the precipitant cation type in a series of chlorides (NaCl, KCl, LiCl, NiCl2, CuCl2, CoCl2) on the structure of lysozyme solutions has been investigated by small-angle X-ray scattering (SAXS) under the conditions favorable for tetragonal crystal growth. The influence of the precipitant concentration on the volume fraction of the oligomers (dimers, octamers) formed before the protein crystallization has been studied. Along with monomers, significant amount of dimers (3.5–13.1%) and octamers (1.7–3.6%) is found in the lysozyme solutions when adding a precipitant. The volume fractions of all oligomers increase with an increase in the precipitant concentration and with a decrease in temperature. In the series of monovalent and divalent ions, the octamer volume fraction increases as K+ – Na+ – Li+ and Cu2+ – Ni2+ – Co2+, respectively.

The Influence of Inorganic and Organic Components of Biofilms with Microscopic Fungi on the Phase Composition and Morphology of Crystallizing Calcium Oxalates

Abstract: The influence of organic and inorganic components of biofilms with microscopic fungi on the phase composition and morphology of precipitating calcium oxalates has been experimentally investigated. It is established that biofilm components may facilitate the formation of metastable calcium oxalates (dihydrous weddellite and trihydrous caoxite) in the crystallization range of monohydrous whewellite. It is shown that the decisive role in the formation of weddellite crystals in biofilms is played, along with oxalic acid, by the citric acid released by micromycetes, Fe3+ ions from the environment entrapped by the biofilm, and the ratio of Ca2+ ions and oxalate ions. The transformation of bipyramidal habit of weddellite into bipyramidal‒prismatic habit may be caused by the presence of Mg2+ and $${\text{SO}}_{4}^{{2 - }}$$ ions in the crystallization medium.

Crystallographic Approach to the [2 + 2] Photocycloaddition Topochemical Reactions of Unsaturated Compounds with Single Crystal Retention

Abstract: Based on the results of authors' studies, an approach to the analysis of [2 + 2] photocycloaddition (PCA) topochemical reactions of unsaturated compounds, occurring in a single crystal with either its retention or decomposition under exposure to visible light, has been developed. The main crystal packings, favorable for photoreaction in crystal, are revealed. Conditions for PCA reaction with single crystal retention are established. The factors increasing the probability of implementing crystal packing motifs that are favorable for this reaction (by chemical modification of structural units) are analyzed. The fact of extraordinary implementation of both direct and back (under UV irradiation) photoreactions in the same single crystal is explained.

Minimal Cayley Graphs of Crystallographic Groups

Abstract: The Cayley graphs of crystallographic groups $$G_{p}^{p}$$, constructed on the minimal number of generators, are discussed. Some theorems on the existence of minimal nets, homeomorphic to such graphs, are proven. The Cayley graphs of planar and Fedorov groups, related to the arrangement of molecular crystals, are considered in detail.

Nonlinear Optical Crystals for Second Harmonic Generation

Abstract: Some important nonlinear optical crystal families in three spectral regions (DUV-FIR) have been discussed with reference to their anionic groups. In the M–F–IR region iodides and chalcopyrite-type compound, in the Vis-NIR region sillenites, perovskites and KTP families and in the DUV region borate compound have been investigated. Their important optical and structural factors have been presented. As moderate birefringence increases phase matching wavelength range, the birefringence measurement has been described in more detail. Recent research has focused on optimizing the structure for obtaining high-LDT crystals in the M–F–IR region and removing the layering structure to achieve large-sized crystals in the DUV region. The entry of small ions in the first case and the replacement of stronger interlayer ions such as Ba and Sr, which have a stronger bond with double layer in the second case, are the solutions presented. Combination of two polarized structure units in such a way to make constructive superposition is followed to rise SHG efficiency. The crystals with 3D network are promising for large size growth.

Nanostructured Crystals of Fluorite Phases Sr1 – xRxF2 + x (R Are Rare-Earth Elements) and Their Ordering. 13: Crystal Structure of SrF2 and Concentration Dependence of the Defect Structure of Nonstoichiometric Phase Sr1 – xLaxF2 + x As Grown (x = 0.11, 0.20, 0.32, 0.37, 0.47)

Abstract: The defect structure of as-grown SrF2 and nonstoichiometric phases Sr1 – xLaxF2 + x (x = 0.11, 0.20, 0.32, 0.37, 0.47) single crystals, grown from a melt under identical conditions, has been studied by X-ray diffraction analysis. All crystals belong to the CaF2-type structure, sp. gr. $$Fm\bar {3}m$$ . Deficit of fluorine anions is found in the 8c site in SrF2. Interstitial anions are not visualized in SrF2 in difference electron-density maps. The Sr1 – xLaxF2 + x phases exhibit the presence of vacancies in the main anion motif and interstitial fluorine ions of three types: in two sites 32f (w, w, w) with different coordinates w and in one site 4b. A model of the defect structure of Sr1 – xLaxF2 + x phase is proposed, according to which interstitial fluorine ions and impurity cations La3+ are grouped into clusters of the [Sr1 – nLanF26] tetrahedral configuration. Calculations based on structural data revealed that the average number of La3+ ions per cluster linearly increases from 2.6 to 3.13 with an increase in the LaF3 concentration. The average crystal volume corresponding to one cluster decreases from 1170.6(3) to 336.1(5) A3. The volume of the anion cluster core decreases from 2.52(7) to 2.42(7) A3, passing through a minimum in the composition with x = 0.32, which is similar to that of congruently melting phase, and then increases to 2.44(9) A3 at х = 0.47. Dynamic thermal displacement of matrix anions in Sr1 – xLaxF2 + x is observed in the [111] direction towards the cubic void center in the anion sublattice. Therefore, according to the mechanism of electrical conductivity, anion jumps are most likely in this direction.

Cluster Self-Organization of Intermetallic Systems: 124-Atom Cluster 0@12@32@80 and 44-Atom Cluster 0@12@32 for the Self-Assembly of Li 48 Na 80 Ga 332 -oF920 Crystal Structure

Abstract: A combinatorial and topological analysis has been performed and self-assembly of the Li48Na80Ga332-oF920 crystal structure has been simulated (sp. gr. Fmmm, a = 24.666 A, b = 15.974 A, c = 45.271 A, V = 17 837 A3) using computer methods (the TOPOS program package). It is found that there are 11 827 versions of cluster representation of an atomic 3D net with the number of structural units from 4 to 14. Two framework-forming icosahedral clusters ico-K124 and ico-K44 are determined. The chemical composition of the shells of the three-layer 124-atom nanocluster ico-K124 is 0@12(Ga12)@32(Li20Ga12)@80(Li4Na16Ga60), its diameter is 17 A, and the symmetry is mmm. The chemical composition of the shells of the two-layer 44-atom nanocluster ico-K44 is 0@12(Ga12)@32(Li20Ga12), its diameter is 11 A, and the symmetry is 2/m. The symmetry and topology code of self-assembly of the crystal structure has been reconstructed from iсо-K124 and ico-K44 nanocluster precursors in the following form: primary chain → layer → framework. Ga7 clusters and dual chains of Ga atoms occupy 3D-framework voids.

Symmetry of Structures That Can Be Approximated by Chains of Regular Tetrahedra

Abstract: The noncrystallographic symmetries of chains of regular tetrahedra are determined by mapping the system of algebraic geometry and topology designs to the structural level. It has been shown that the basic structural unit of such a chain is a tetrablock: a seven-vertex linear aggregation over faces of four regular tetrahedra, which is implemented in linear (right- and left-handed) and planar versions. The symmetry groups of linear and planar tetrablocks are isomorphic, respectively, to the projective special linear group PSL(2, 7) of order 168 and the projective general linear group PGL(2, 7) of order 336. A class of structures formed by an assembly of tetrablocks having no common tetrahedra is introduced. Examples of tetrablock assembly over common face, leading to a Boerdijk–Coxeter helix, an α helix, and a helix used as one of collagen models are presented.

New Structure for Photoconductive Antennas Based on {LTG-GaAs/GaAs : Si} Superlattice on GaAs(111) A Substrate

Abstract: The structural characteristics of a new structure for photoconductive antennas have been investigated. This structure is a multilayered epitaxial film grown on a GaAs(111)A substrate; it consists of alternating undoped low-temperature grown GaAs (LTG-GaAs) layers and GaAs layers synthesized in the standard high-temperature regime and doped with silicon (GaAs:Si). The As4/Ga flow ratio γ is chosen such as to produce p-type GaAs:Si layers. LTG-GaAs layers were grown at an enlarged γ value. The samples grown on GaAs(100) substrates were single-crystal, whereas the single-crystal growth on GaAs(111)A substrates changed to polycrystalline when the film thickness reached 320–340 nm. The sizes of As precipitates in annealed samples, their distribution over the film thickness, and specific features of their crystal structure have been analyzed.

Synthesis of YBCO Nanopowders and Properties of Ceramics on Their Basis

Abstract: The structure, morphology, density, and resistivity of nanostructured superconducting YBCO-based ceramics, fabricated from nanopowders prepared by burning nitrate-organic precursors, have been investigated.

Circular Dichroism in Cholesteric Liquid Crystals

Abstract: The circular dichroism in cholesteric liquid crystals (CLCs) has been studied in the absorption bands of dissolved dichroic dyes possessing both the positive and negative linear dichroism. The circular dichroism is studied depending on the position of CLC selective reflection band with respect to the dye absorption band. The induced circular dichroism due to dye absorption is compared to intrinsic CLC circular dichroism due to the light diffraction from the periodic chiral structure.

Nanoscale Effects in PbF 2 –CdF 2 Solid Solutions

Abstract: The specific features of the fluorine-ion transport in nanostructured samples of Рb1 – xCdxF2 solid solutions are studied by the molecular dynamics method. The diffusion coefficients DF of fluorine ions in these samples increase by several orders of magnitude (at room temperature) as compared to bulk crystals. The experimentally observed maximum of fluorine diffusion at 30 mol % CdF2 could be reproduced for spherical nanoparticles more than 15 nm in size. It is shown that the mobility of the F– ions located on the surface of nanospherical particles exceeds several times the mobility of fluorine anions in the particle bulk.

Electron Microscopy of the Surface of Dental Implants and Metal-Containing Nanoparticles Obtained in Supernatants

Abstract: The surface of two dental implant systems, “Nobel Biocare” and “Alpha BiO”, and metal-containing nanoparticles, isolated from the tissues surrounding dental implants, has been investigated. The implant surface structure, the elemental and phase composition of particles, and their arrangement in the granulation tissue have been studied by X-ray tomography, transmission and scanning electron microscopy, z-contrast scanning transmission microscopy, electron diffraction, and energy-dispersive mapping, using microscopes Quanta 200-3D, FEI Тechnai Osiris at an accelerating voltage of 200 kV, and an X-ray microtomograph TOMAC. An analysis of the relief indicates that the emission of nanoparticles from the “Alpha BiO” implant surface to the adjacent tissues is more likely than from the “Nobel Biocare” implant surface. The particles of micrometer and submicrometer sizes of “Nobel Biocare” implants are found to consist mainly of titanium dioxide of both modifications, rutile and anatase, whereas in the case of “Alpha BiO” implants, along with titanium dioxide and titanium nitride, there are aluminum oxides in the particle composition. The elemental composition of nanoparticles is more diverse; it includes Fe, Ca, Na, Cl, S, Si, P, etc. It is revealed that microbial contamination does not always play the leading role in the suppression of previously obtained osteointegration.

The Investigation of the Medieval Russian Bronze Reliquary Cross Pendant Using a Complex of Nondestructive Methods

Abstract: The medieval Russian bronze reliquary cross pendant was investigated using a complex of nondestructive methods in order to determine the degree its integrity and identify the material filling its internal cavity. The metal composition is established. It is found that the cross material was subjected to spatially inhomogeneous corrosion and that the cavity is filled with soil. It is shown that application of complementary nondestructive methods provides the most reliable information on historical heritage objects.

Mesophase-Preceding Crystal Packing of 4,4'-Dialkyl-Substituted Salicylideneanilines; C 10 H 21 O–C 6 H 3 (OH)–CH=N–C 6 H 4 –С 7 Н 13 ) Structure

Abstract: The crystal structure of 4,4'-substituted salicylideneaniline C10H21O–C6H3(OH)–CH=N–C6H4–C7H13 has been investigated by X-ray diffraction. A high degree of disorder of both alkyl chains is revealed. The crystal packing consists of alternating loose aliphatic and closely packed aromatic regions. Weak directional interactions of the С–Н···π type are found in aromatic regions. Specific features of the mesogenic compound crystal packing preceding the mesophase, melting of these compounds, and the formation of mesophase upon isotropic melt cooling are discussed based on the X-ray diffraction and differential scanning calorimetry data.

A Novel Sodium and Chromium Borophosphate Na{Cr[BP2O7(OH)3]}: Synthesis, Crystal Structure, Hydrogen Bonding, and Comparative Crystal Chemistry

Abstract: A novel sodium and chromium borophosphate, obtained by hydrothermal synthesis in the Na2O–P2O5–B2O3–Cr2O3–Н2О system, has been investigated using X-ray diffraction and IR spectroscopy. The monoclinic cell parameters are found to be a = 10.4220(3) A, b = 8.2468(2) A, c = 9.2053(3) A, β = 116.568(4)°, and V = 707.63(4) A3; sp. gr. С2/с. The structure is interpreted and refined to the final reliability factor R1 = 2.23% in the anisotropic approximation of atomic displacements using 1311 reflections, I > 2σ(I). The novel compound is relative to the family of alkaline borophosphates with the general formula A{M[BP2O7(OH)3]} (A is an alkaline or alkaline-earth element; M is a transition метал) and is described by the crystallochemical formula (Z = 4) Na{Cr[BP2O7(OH)3]}, where the compositions of borophosphate anion and microporous framework are in square brackets and braces, respectively. The presence of alternative systems of strong symmetric hydrogen bonds is established; the localization of all hydrogen atomic sites has made it possible to analyze them in detail. An additional electron density peak is found, which can be interpreted as a statistically distributed proton H+. The IR spectrum is characteristic of compounds with strong hydrogen bonding; it confirms the statistical proton distribution over subsites around the inversion center. It is suggested that representatives of this family may possess proton conductivity.

Raman Scattering of Light in Diamond Microcrystals

Abstract: Raman spectra of monodisperse crystalline diamond powders have been studied in dependence of the sample sizes. Raman scattering was excited by a near-IR cw laser (λ0 = 785 nm), which ensured suppression of the photoluminescence signal. Powders consisting of close-packed particles in the form of nanodiamonds (0.2–0.3 µm in size) and microdiamonds of specified sizes (up to 180 µm) have been studied. The recorded Raman spectra of the microdiamond powders are characterized by anomalously high intensity, which is related to the excitation radiation trapping in microparticles, the size of which exceeds significantly the lasing wavelength. The Raman spectra contain a sharp line at a frequency of 1332 cm–1 and additional bands in the vicinity of fundamental-mode overtones.

Anisotropy of Ionic Conductivity of TbF3 Crystals

Abstract: Temperature measurements (in the range of 375–830 K) of the ionic conductivity of terbium trifluoride single crystals (structure type β-YF3) along three unit-cell crystallographic axes (a, b, and c) have been performed. It is found that TbF3 crystals (orthorhombic system, sp. gr. Pnma) have a weak anisotropy of electrical conductivity: σ||b/σ||a = σ||b/σ||c ≈ 2. The conductivity along the b axis is σ||b = 8 × 10–6 S/cm at 500 K. The anisotropy of fluorine-ion conductivity in rare-earth fluorides with β-YF3, LaF3 (tysonite), and β-BaTm2F8 structures is discussed in the contest of the specific features of their atomic structure.

Experimental Study of Two-Beam X-Ray Diffractometry Using Synchrotron Radiation

Abstract: A new scheme of two-beam X-ray diffractometry on the “X-Ray Crystallography and Physical Materials Science” (XCPM) beamline at the Kurchatov Synchrotron Radiation Source (KSRS) has been experimentally investigated. The scheme includes a standard double-crystal monochromator and a narrow slit installed in front of the sample. Measurements have been performed for the Si 111 and 311 reflections in the monochromator and the Si 111 and 220 reflections in the sample crystal. It is shown that this scheme allows one to obtain a near-proper diffraction reflection curve even in the case of symmetric diffraction if the Bragg angle for the monochromator exceeds the Bragg angle for the crystal sample by a factor of 2 or more. The experimental results coincide well with the theory.

Investigation of the Pigments of the Ancient Portrait Terracotta Found in the Kerch Bay

Abstract: The results of studying an ancient terracotta sculpture found in the Kerch bay are presented. An attempt is made to reconstruct the initial terracotta color and determine the palette composition of ancient painters using a complex of analytical methods: optical and scanning electron microscopy, energy-dispersive X-ray microanalysis, X-ray diffraction, and IR spectroscopy. A study of the terracotta made it possible to reveal a polychromatic character of the decor and determine the composition of the pigments. Iron/manganese compounds were used as a dark brown pigment for coloring the hair, beard, and moustache of the ceramic sculpture. Red ochre and gypsum were applied for coloring lips. Sandarac was used as an adhesive layer for depositing inorganic pigments, as well as a protective layer. The portrait terracotta is suggested to play a role of a ship decoration element.

Sortases from a Probiotic Lactobacillus rhamnosus GG: Cloning, Expression, Purification, Crystallization and Preliminary X-Ray Diffraction Study

Abstract: Sortases are membrane-associated cysteine transpeptidases found mainly in Gram-positive bacteria. They have been intensely studied in pathogenic strains as they play a key role in covalent attachment of various virulence-associated surface proteins including pili to the cell wall and also in biogenesis of pili. The recent identification of sortase genes in some members of gut microbiota indicates their likely role in establishing interaction with the human gastrointestinal tract for probiotic traits. While the structural information about sortases thus far is limited to pathogenic bacteria, here we have the produced recombinant form of housekeeping (SrtA) and pilin-specific (SrtC1) sortases from gut-adapted probiotic strain Lactobacillus rhamnosus GG and crystallized them. The crystals of SrtA and SrtC1 diffracted to a resolution of 1.9 A and belonged to monoclinic and tetragonal crystal forms respectively.

Specific Features of the Formation of Gallium, Indium, Bismuth, and Antimony Nanoparticles

Abstract: Gallium, indium, bismuth, and antimony nanoparticles were obtained by vacuum evaporation technique onto glass carbon substrates at an argon gas pressure of 6 × 103 Pa and a melt temperature of 330–380°C. It is established that the evaporation time and temperatures of the melt and substrate determine the sizes, density, and shape of the nanoparticles and crystallites. The high surface tension of gallium melt and excess of the substrate temperature above the gallium crystallization temperature provide the density increase with the decrease of Ga nanoparticle dimensions. On the contrary, the low surface tension and excess of crystallization temperature above the substrate temperature facilitates the formation of antimony crystallites in a shape similar to the Sb unit cell. An increase of the melt and substrate temperatures increased the dimensions and density of indium and bismuth nanoparticles.

Radiation-Induced Changes in the Degree of Crystallinity of Powdered Polytetrafluoroethylene

Abstract: An analysis of the diffraction patterns of powdered polytetrafluoroethylene (PTFE) γ-irradiated at room temperature in a nitrogen atmosphere to doses of 10–500 kGy with a fluence of 1.50 ± 0.3 Gy/s has shown that the diffraction peak 100 of the crystalline phase at 2θ ∼ 18° and the halo at 2θ = 10°–25° are most sensitive to ionizing radiation. It is found that the intensity, FWHM, and position of the maximum of reflection 100 change with an increase in the absorbed dose; this fact is indicative of the doublet nature of the peak profile. It is established that the doublet components differently response to ionizing radiation. The interplanar spacings, amplitude and sign of arising stress, and the degree of crystallinity (DOC) of polymer are calculated as functions of the irradiation dose. The radiation-induced change in the DOC of PTFE should be considered as a complex process, which includes radiative destruction and topochemical reactions of different types in crystals.

New Crystals in the CsHSO 4 –CsH 2 PO 4 –NH 4 H 2 PO 4 –H 2 O System

Abstract: The phase equilibria in the CsHSO4–CsH2PO4–NH4H2PO4–H2O four-component aqueous salt system have been studied. The crystallization ranges and solubilities have been determined for the CsHSO4, NH4H2PO4, and (Cs,NH4)H2PO4 phases and the phases obtained for the first time: (Cs,NH4)4(HSO4)3(H2PO4) and (Cs,NH4)2(HSO4)(H2PO4). Cs3NH4(HSO4)3(H2PO4) and CsNH4(HSO4)(H2PO4) crystals of stoichiometric composition have also been grown for the first time.