共查询到20条相似文献,搜索用时 31 毫秒
1.
Xinxin Zhuang Genbo Su Youping He Guozong Zheng 《Crystal Research and Technology》2006,41(10):1031-1035
A new single crystal for ultraviolet light filter, KCNSH (Potassium Cobalt Nickel Sulfate Hexahydrate) was designed and its crystal structure was studied using X‐ray diffraction in this paper. The empirical of the title compound is K2Co0.1Ni0.9(SO4)2.6H2O with formula weight 437.15. KCNSH crystal belongs to the monoclinic space group P2(1)/c, a=6.1390(3)Å, b=12.1839(6)Å, c=9.0095(4)Å, α=γ=90°, β=105.060(2)°, V=650.74(5)Å3, Z=2, Dc=2.231g/cm3. Using the cooling solution method, we have grown a deep green KCNSH crystal with dimension of 12×12×40mm3. The transmission spectrum of KCNSH in the range from UV to near IR wavelengths, its thermal properties, and the relationship between the structure and optical transmission properties are also studied and further discussed in this paper. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
2.
B.P. Chandra 《Crystal Research and Technology》1982,17(4):505-508
Crystalloluminescence and mechanoluminescence of Ba(ClO3)2 · H2O and 2 K2SO4 · Na2SO4 crystals are investigated. The crystalloluminescence spectra are almost similar to the photoluminescence spectra; however, they differ completely from the mechanoluminescence spectra. The crystalloluminescence excitations may take place due to the various processes: (i) the recombination of ions, (ii) from amorphous to crystalline transition, (iii) from the phase change during the crystallization, and (iv) from the dielectric breakdown by the electric field produced due to the creation of microfracture during the crystal growth. It is concluded that the crystalloluminescence excitation in Ba(ClO3)2 · H2O and 2K2SO4 · Na2SO4 crystals may be chemical in origin. 相似文献
3.
E. V. Kiryanova 《Crystal Research and Technology》2010,45(10):1017-1024
Detailed precision investigation of aqueous solutions of NaBr·2H2O, KBr, RbNO3, and K2SO4 salts showed oscillations of crystal‐solution phase equilibria in the temperature range of 15–45 °C. The maximum deviations from the smooth correlation between the saturation temperature and the salt concentration (up to 4% of concentration and up to 10 °C) were found to correspond to simplest salt‐water ratios. Recently, similar trends were observed for NaNO3, KNO3 and K2CrO4 solutions. Oscillation amplitudes for saturation temperature in the investigated series decreased in the following orders: Na+→K+, Rb+, NH4+ (nitrate systems), CrO42–→SO42– and Br–→NO3– (potassium systems), and NO3–→Br– (sodium systems). Increase in total content of impurities (2‐4‐fold) in solution results in 1.5‐2‐fold elevation of the oscillation amplitudes. A concept of nanoheterophase solution was suggested to account for the observed temperature‐concentration oscillations. The concept is based on the original experimental data on interrelated variation of different properties of aqueous salt solutions depending on their concentrations. Characteristic features of the phase diagrams are discussed and influence of the oscillations on crystal growth is elucidated. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
4.
B. Mazzarotta 《Crystal Research and Technology》1990,25(8):903-911
Crystallization of glaserite (double salt of potassium and sodium sulphate) from aqueous solutions was studied by determining solubility, metastable zone width, growth and dissolution kinetics. Solubility measurements confirmed the presence of a large range of mother liquor compositions from which the precipitation of glaserite at about 73 – 76 wt% K2SO4 is obtained: inside this region the solubility lines resulted curvilinear. The metastability zone is quite large, ranging from 14 to 23 °C, and mainly increases by increasing the Na2SO4 content in the mother liquor. The growth rate of glaserite is second order, slightly size dependent and primarily controlled by diffusion as for K2SO4 but both growth and dissolution constants are quite lower than those for K2SO4. 相似文献
5.
Nataliia Strutynska Marina Bondarenko Nikolay Slobodyanik Vyacheslav Baumer Igor Zatovsky Kostyantin Bychkov Anna Puzan 《Crystal Research and Technology》2016,51(10):627-633
Crystallization of high temperature self‐flux of system Na2O‐K2O‐TiO2‐P2O5 was investigated at different molar ratios (Na+K)/P = 0.9; 1.0 or 1.2 and Na/K = 1.0 or 2.0 over the temperature range 1000–650°C. The conditions of formation of complex phosphates K0.10Na0.90Ti2(PO4)3 (NASICON‐related) and K0.877Na0.48TiІІІ0.357TiІV1.643(PO4)3 (langbeinite‐related) have been established. The new obtained compounds were investigated using FTIR‐spectroscopy, powder and single crystal X‐ray diffraction and optical microscopy methods. The influence of alkaline metal nature on the structure formation of complex phosphates in the high temperature self‐fluxes is discussed. 相似文献
6.
M. S. Grigor’eva A. é. Voloshin E. B. Rudneva V. L. Manomenova S. N. Khakhanov V. Ya. Shklover 《Crystallography Reports》2009,54(4):637-644
The K2Co(SO4)2 · 6H2O-K2Ni(SO4)2 · 6H2O system has been studied, and a series of K2Ni(SO4)2 · 6H2O/K2Co(SO4)2 · 6H2O bicrystals have been grown. The processes of defect formation at the substrate/layer interface K2Co(SO4)2 · 6H2O/K2Ni(SO4)2 · 6H2O are studied by probe microanalysis, X-ray topography, and optical microscopy. It is found that inclusions and threading
dislocations are formed at the interface, due to which elastic stresses relax in the crystal. Nickel is nonuniformly distributed
in the layer; its concentration decreases with an increase in the layer thickness, which is indicative of substrate dissolution
in the initial stage of interaction. A way for the elastic mismatch stresses to relax in heterostructures of brittle crystals
obtained from solutions at low temperatures is proposed which implies the formation of inclusions at the substrate/layer interface.
Original Russian Text ? M.S. Grigor’eva, A.é. Voloshin, E.B. Rudneva, V.L. Manomenova, S.N. Khakhanov, V.Ya. Shklover, 2009,
published in Kristallografiya, 2009, Vol. 54, No. 4, pp. 679–687. 相似文献
7.
Effect of monovalent salts on morphology of calcium carbonate crystallized in Couette‐Taylor reactor
Monovalent ionic additives, Na+, K+ and NHequation/tex2gif-stack-1.gif impact on the morphology and agglomeration of CaCO3 crystals. As increasing the additive concentration, the regular shaped crystals such as rhombohedron and spindle are changed to irregular one due to the inclusion of Na+ and K+ into the crystal structure. The inclusion of Na+ and K+ is detected using ICP‐AES. The partition of coefficients of Na+ and K+ are estimated as 9.74 × 10–4, 9.73×10–4, respectively and the amount of inclusion in the crystals is about 2×103 ppm. However, the inclusion of ions does not modify a crystal structure of calcite. Since NH4+ is large in radius, it is not included in crystal but shifts the spindle shape of crystal to the rhombohedral one. It is interesting to find that such modification of crystal morphology begins to appear at high additive concentration (0.05 M). In addition, the crystal agglomeration is promoted because the electric repulsive charge is reduced as increasing the additive concentration. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
A study was made on a isothermal process for the crystallization of potassium sulfate as an alternative to the cooling process. The process employs addition of 1‐propanol to aqueous salt solutions to achieve the “saltingout” of the K2SO4. This work was carried out using an automated Mettler Toledo model RC1 reactorcrystallizer with 800 ml capacity, and controlled isothermally at 25 °C to test the crystallization of K2SO4 by addition of the alcohol, and from 50 to 10 °C for the cooling crystallization. In both systems, the line of nucleation points was shown to be approximately parallel to the saturation curve, with an average width of 13°C or 3 % mass for crystallization by cooling, compared with 0.2 to 1 % by salting‐out. In experiments on crystallization by cooling, the K2SO4 crystals were 0.27 mm in mean size, showed 7 % agglomeration, and contained 8.5 % moisture. Crystals obtained by salting‐out had a mean size of 0.79 mm, 28 % agglomeration, and 9‐10 % moisture content. A crystal shape factor of approximately of 0.7 was obtained in both systems, apart from the agglomeration. 相似文献
9.
The thermal decomposition of polyhalite (K2SO4 · MgSO4 · 2 CaSO4 · 2H2O) was investigated by DSC/TG and X-ray powder diffraction. The decomposition of the polyhalite starts at 285 °C in releasing the crystal water within one step. Simultaneously the decomposition of the polyhalite into anhydrite and two solid solutions of the compositions K2SO4 · 1.76 MgSO4 · 0.24 CaSO4 and K2SO4 · 0.64 MgSO4 · 1.36 CaSO4 is taking place. The mechanism of decomposition runs through K2SO4 · MgSO4 CaSO4. This phase reacts immediately to the solid solutions, mentioned above. 相似文献
10.
L. F. Malakhova O. A. Alekseeva N. G. Furmanova S. N. Bocharov L. Yu. Kryuchkova 《Crystallography Reports》2010,55(2):206-209
Single crystals without Co and Ni have been crystallized by the substitution method in the K2Ni(SO4)2-Ce(SO4)2-H2SO4-H2O system using K2Co(SO4)2 · 6H2O, K2 (Co,Ni)(SO4)2 · 6H2O, or K2Ni(SO4)2 · 6H2O as protocrystals. The structure of the single crystals obtained has been established by X-ray diffraction analysis. The
crystal structure contains dimer complex anions [Ce2(μ-SO4)2(SO4)6]8−, K+ cations, and crystallization water molecules. 相似文献
11.
M. Georgievskaya B. Albert R. Bubnova G. Cordier C. Bhtz S. Filatov 《Crystal Research and Technology》2008,43(11):1150-1160
In the potassium‐rich part of the binary system Na4B8O14‐K4B8O14 solid solutions have been found that can be described with the formula (Na1‐xKx)4B8O14 with 0.45 ≤ x < 1.0. The crystal structures of (Na0.25K0.75)4B8O14 and (Na0.45K0.55)4B8O14 were refined at room temperature by the Rietveld method. The solid solutions crystallize like K4B8O14 in the triclinic crystal system, space group P ‐1, with K partially substituted for Na. An ordered distribution of the alkali atoms over the four cation sites at room temperature has been discovered. The structure of (Na0.25K0.75)4B8O14 was also refined for data collected at 300 and 500 °C. The refinements show that sodium and potassium atoms are less ordered at higher temperatures. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
12.
B. Mazzarotta 《Crystal Research and Technology》1989,24(5):503-511
The crystallization of K2SO4 from aqueous solutions of glaserite (a double salt of sodium and potassium sulphate) was investigated in an MSMPR cooling apparatus at 35 °C. The precipitation of K2SO4 at an average purity of 93 wt.% was obtained and the crystallization kinetics were derived from the experimental data. The nucleation and growth rates here obtained were, respectively, remarkably higher and slightly lower than those relevant to pure K2SO4: this behaviour may be explained by a faster nucleation and a slower growth of crystals containing also Na2SO4. The effect of small (0.05%) calcium additions to the feed was also tested, which caused an increase of supersaturation and a depression of the growth kinetics, whereas the nucleation one was not appreciably modified. 相似文献
13.
E. V. Kiryanova 《Crystal Research and Technology》2011,46(4):331-339
Using the examples of aqueous salt solutions NaNO3, KNO3, RbNO3, K2SO4, NaBr·2H2O, KBr, and NH4NO3, it was experimentally proven that the new phenomena, i.e. temperature‐concentration oscillations of crystal‐solution phase equilibria detected previously in the range of 15–45 °C remain in the presence of trace impurities (10‐4–10‐3 wt. %) of ion‐active organic matters. The signs of breaks transformation into pair oscillations of “maximum‐minimum” type are established for the K2SO4, NaBr, KBr solutions. The efficiency of influence of trace impurities on phase equilibria sharply rises in the areas of the temperature‐concentration oscillations (the saturation temperature ranges up to 10 K). The impurity efficiency is promoted by the presence of the amides in its content (as compared with the sulphates) and an increase in length of the hydrocarbon radical. The phenomenon is absent in case of an addition of ion‐inactive compounds. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
14.
S. Haussühl 《Crystal Research and Technology》1992,27(2):267-272
Large single crystals of optical quality of triclinic K2Cr2O7 have been grown from aqueous solutions. Their morphological and growth properties are not compatible with point symmetry 1 . Complete sets of the elastic constants and their temperature derivatives were determined from ultrasonic resonances of plane-parallel plates. The elastic behaviour and also the thermal expansion are highly anisotropic. Owing to very strong photoelastic effects these crystals are suited for certain acousto-optic deflection devices. 相似文献
15.
N. L. Sizova N. E. Novikova V. L. Manomenova E. B. Rudneva A. E. Voloshin 《Crystallography Reports》2016,61(3):443-448
The microhardness on the (010) and (001) planes in K2Co(SO4)2 · 6H2O crystal has been measured by the Vickers indentation method. Its values are, respectively, 11500 and 1300 MPa. No microhardness anisotropy of the first kind is revealed on either plane. The fracture geometry under indentation by a spherical indenter and Vickers and Knoop indenters is studied. The crystal has lower brittleness than the isomorphic Cs2Ni(SO4)2 · 6H2O crystal. 相似文献
16.
The elastic, piezoelectric and dielectric constants of pentaerythritol, C(CH2OH)4, have been computed employing the method of long waves and the unscreened rigid ion potential model developed by RAMAMOORTHY and KRISHNAMURTHY. Piezoelectric contribution is taken into account in the computation of elastic constants. This is the first report on the piezoelectric and dielectric constants of pentaerythritol. In the notations followed by LANDOLT-BORNSTEIN the computed piezoelectric constants are: g14 = 4.82, g15 = 4.37, g31 = 16.21 and g36 = 5.89 (in unit of 10−1Vm/N) and the static dielectric constants are: K1 = 2.38 and K3 = 2.47. The hydrogen bonding in pentaerythritol has no effect on its dielectric behaviour. Calculation of acoustic velocities in piezoelectric crystals and as a special case to the crystals of class 4 is explained in detail. Sound velocities calculated from the elastic, piezoelectric and dielectric constants computed in the present investigation agree with the experimental values determined by the ultrasonic method. 相似文献
17.
S. Haussühl 《Crystal Research and Technology》1994,29(1):119-124
Single crystals of the title compounds having optical quality and dimensions of several cm were grown from aqueous solutions. The elastic and thermoelastic constants were determined from ultrasonic resonance frequencies of thick plates. The true point symmetry of K2S2O6 and Rb2S2O6, which is screened by a hexagonal hypermorphy, could be clearly revealed to be trigonal (32) by the existence of the elastic constant c14. In the case of CaS2O6 · 4H2O and SrS2O6 · 4H2O the constant c14 of the specimens appeared too small to confirm the trigonal symmetry group required from electrooptic and non-linear optic effects unambiguously. The isotypy of K2S2O2 and Rb2S2O6 as well as that of CaS2O6 · 4H2O and SrS2O6 · 4H2O is confirmed by their elastic behaviour. The mean elastic stiffness of dithionates is closely related to that of the corresponding sulphates. In the vicinity of the second-order phase transition of K2S2O6 near 235 K weak anomalies of the temperature derivatives of the longitudinal elastic stiffnesses are observed. 相似文献
18.
R. K. Rastsvetaeva I. V. Pekov N. V. Chukanov K. A. Rozenberg L. V. Olysych 《Crystallography Reports》2007,52(5):811-818
The high-sodium variety of cancrinite [Si6.3Al5.7O24][Na2(H2O)2][Na5.7(CO3)0.9(SO4)0.1(H2O)0.6] (Kovdor Massif, Kola Peninsula, Russia) and the calcium-containing variety of cancrisilite [Si6.6Al5.4O24][(Na1.2Ca0.4)(H2O)1.6][Na6(CO3)1.3(H2O)1.2] (Khibiny Massif, Kola Peninsula, Russia) are studied. The trigonal unit cell parameters of the crystal structures under investigation are as follows: a = 12.727(4) Å, c = 5.186(2) Å, and space group P3 for the former mineral and a = 12.607(4) Å, c = 5.111(1) Å, and space group P3 for the latter mineral. The reduced symmetry of the new varieties as compared to the symmetry of typical cancrinite and typical cancrisilite is associated with the specific features in the arrangement of the carbonate groups and water molecules in channels. This inference is confirmed by the IR spectroscopic data. 相似文献
19.
Natural brines sampled from Sebkhats in southern part of Tunisia are considered to be seawater‐type solutions. The equilibrium solubility of this kind of solutions might be described by the fivefold seawatertype system Na+, K+, Mg2+, Cl‐, SO42‐ // H2O. The crystallisation sequences of salts, observed under solar evaporation, of two different Tunisians brines is discussed. Very important differences between the foreseeable results, based on the Equilibrium Solubility Diagram at 25 °C, and the experimental ones are settled. An attempt to explain the differences, based on the so‐called “solar sequences” as well as the “solar diagram” of evaporation, is made. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
20.
Calcium phosphate based bioactive quaternary glass systems P2O5-CaO-Na2O-K2O were prepared by melt growth technique. Glasses were prepared in five different compositions by fixing P2O5 at 47 mol% and CaO at 30.5 mol% and by varying the K2O and Na2O concentrations. The structural properties of the glasses are analyzed using X-ray diffraction (XRD) studies and scanning electron microscopy (SEM) studies; and the composition of the glasses are studied using energy dispersive X-ray spectrum (EDS). The microhardness of the glass systems are studied by Vickers hardness measurements and the bioactivity of the glasses are studied using in vitro study. The thermal properties have been examined by means of thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The ultrasonic velocity measurements show that the addition of K2O contents produces non-bridging oxygen ion and hence weaken of the glass structure. The weakening of the glass structure reduces the ultrasonic velocity and hence an increase in attenuation. 相似文献