Nitrate Crystals Research Articles

Crystallization of ionic salts for calibration of differential scanning calorimeters

This study explores the possibility of using inorganic salts for temperature calibration of Differential Scanning Calorimeters (DSC) on cooling. The crystallization and melting of sodium nitrate, potassium nitrate, and rubidium nitrate has been studied at several cooling and heating rates. It has been found that these salts crystallize at almost the same temperature, at which they melt, meaning that they do not practically supercool. The DSC data have indicated that the median value of the supercooling is around 0.4–0.8°C. The study suggests that the process of crystallization of these and possibly other inorganic salts can be considered for developing new standards to calibrate DSC on cooling.

Measurement of Crystal Face Specific Growth Kinetics

An instrument for measurement of face specific growth kinetics of crystals growing in a solution is developed and applied to crystallization of sodium nitrate (NaNO3) and potassium dihydrogen phosphate (KH2PO4, KDP). The device consists of three major components, a stereovision imaging system that captures in real time the size change in each face direction of the crystal, an ATR-FTIR probe measuring solution concentration and supersaturation, and a small purpose-designed crystallizer that allows a crystal to be fixed in the solution and adequate solution mixing so the concentration measured can reflect the solution concentration near the surfaces of the crystal. The growth rates of all independent faces of NaNO3 and KDP crystals were derived at each time interval. For the NaNO3 crystal, growth rates in the temperature range 298.15–318.15 K and the supersaturation range 0.01–0.11 were measured, enabling a systematic kinetic study. For the KDP crystal, the growth rates were measured just to show the capabi...

Isoconversional Kinetics of Nonisothermal Crystallization of Salts from Solutions.

In this study, differential scanning calorimetry (DSC) has been applied to measure the kinetics of nonisothermal crystallization of potassium nitrate and ammonium perchlorate from unsaturated and saturated aqueous solutions. DSC data have been analyzed by an advanced isoconversional method that demonstrates that the process is represented by negative values of the effective activation energy, which varies with the progress of crystallization. The classical nucleation model can be used to predict and understand the experimentally observed variation in the effective activation energy. The saturated and unsaturated solutions have demonstrated distinctly different crystallization kinetics. It is suggested that the unsaturated solutions undergo a change in crystallization mechanism from homogeneous to heterogeneous nucleation.

Vibrational Energy Relaxation of Water Molecules in a Hydrated Lithium Nitrate Crystal

Water molecules in hydrated salts often have a well-defined geometrical arrangement and form an excellent model system for studying the effects of the hydrogen-bond environment on vibrational energy relaxation. Hydrated lithium nitrate contains two distinct types of crystal water molecules. One water molecule makes strong and weak hydrogen bonds; the other water molecule makes two bifurcated hydrogen bonds. We use femtosecond two-dimensional infrared spectroscopy to probe the vibrational relaxation dynamics of the OD stretch vibration of dilute HDO molecules in lithium nitrate trihydrate. In the temperature range from 22 to 295 K we observe a decrease in vibrational lifetime from 3.8 ± 0.2 to 2.8 ± 0.1 ps for the strongly hydrogen-bonded species, from 5.41 ± 0.08 to 4.14 ± 0.05 ps for the bifurcated hydrogen-bonded species, and from 10.4 ± 0.2 to 8.8 ± 0.4 ps for weakly hydrogen-bonded species. This temperature dependence is opposite to that of the OD stretch vibration of dilute HDO:H2O ice, for which the...

Spectroscopic and theoretical study of the charge transfer interaction effect on the vibrational modes and nonlinear optical properties in l-asparaginium nitrate crystal

Single crystals of l-asparaginium nitrate (LAsnN) were grown by slow evaporation technique. To confirm the crystalline nature of the obtained compound, samples were the subject of an XRPD. The density functional theory (DFT) computations were carried out at B3LYP/6-31G (d) level to reach the optimized geometry, the vibrational spectra and the NLO properties. The excellent agreement between simulated and observed vibrational spectra led to a reliable vibrational assignment. To demonstrate the various charge transfer interactions that stabilize the compound and led to the high nonlinear optical activity, NBO analysis was performed. Also, owing to the hydrogen bond formation, a lowering in the HOMO-LUMO energy gap is noticed. Moreover, as a result of the charge transfer interactions, the symmetry of the nitrate ions was lost and some forbidden modes were excited.

Improved solubility and bioactivity of theophylline (a bronchodilator drug) through its new nitrate salt analysed by experimental and theoretical approaches

Synthesis, crystal structure, vibrational spectroscopy, quantum chemical studies and biological activity of the new semi organic compound, Theophyllinium Nitrate [C7H9N4 O2)+. (NO3)-], are reported here. Crystals of Theophyllinium nitrate (TN) were grown by slow solvent evaporation technique. The crystal packing is dominated by N–H···O intermolecular hydrogen bonds. The cations and anions are aggregated almost parallel leading to a lamellar structure. This molecular aggregation features two alternate hydrogen bonded chain C22(8) and C21(6) motifs. Further, a bifurcated ring R12(4) motifs is also seen. This aggregated molecular sheets are parallel to (2¯06) and (206¯) planes of the crystal. The solubility test is carried out to enhance the physico–chemical activity of the compound. The atomic charge distribution on different atoms of TN has been calculated by Mulliken charge analysis. A detailed interpretation of FT-IR and FT-Raman spectra of TN show that most of the bands are matching between the experimental and theoretical methods. The strong intensity bands and shifting of bands due to intermolecular hydrogen bonds are also investigated. The NBO analysis is carried out to elucidate the stability of the molecule and charge delocalization within the molecule. The HOMO–LUMO analysis reveals molecular stability and chemical reactivity of the present compound. Also, the compound was examined for its antibacterial activity and found to exhibit notable activity against Pseudomonas aeruginosa. This shows that the present compound is a good candidate for the antimicrobial agent apart from its inherent Bronchodilator drug property. Hence, the new compound (TN) may be a good alternative for patients with Chronic Obstructive Pulmonary Disease (COPD) and bacterial infections.

High pressure Raman spectra of monoglycine nitrate single crystal

Single crystal of monoglycine nitrate has been studied by Raman spectroscopy under high pressures up to 5.5GPa. The results show changes in lattice modes in the pressure ranges of 1.1–1.6GPa and 4.0–4.6GPa. The first change occurs with appearance of bands related to the lattice modes as well as discontinuity in the slope of dΩ/dP of these modes. Moreover, bands associated with the skeleton of glycine suggest that the molecule undergoes conformational modifications. The appearance of a strong band at 55cm−1 point to a second phase transition associated with the lattice modes, while the internal modes remain unchanged. These anomalies are probably due to rearrangement of hydrogen bonds. Additionally, decompression to ambient pressure shows that the phase transitions are reversible. Finally, the results show that the nitrate anions play an important role on the stability of the monoglycine nitrate crystal.

Does thiosemicarbazide lead nitrate crystal exist?

The authors of a recent paper (Optik 125 (2014) 2022–2025) claim to have grown a so called thiosemicarbazide lead nitrate (TSLN) crystal by the slow evaporation method. In this comment we prove that TSLN is actually thiosemicarbazide.

Inside Cover: Shape‐Controlled Preparation of Basic Bismuth Nitrate Crystals with High Iodide‐Removal Capacities (ChemNanoMat 2/2016)

Inside Cover: Shape‐Controlled Preparation of Basic Bismuth Nitrate Crystals with High Iodide‐Removal Capacities (ChemNanoMat 2/2016)

Structural, Growth and Characterizations of NLO Crystal: Triglycinium Calcium Nitrate

Single crystals of triglycinium calcium nitrate, a semiorganic nonlinear optical (NLO) material, have been grown by slow solvent evaporation technique at room temperature. The size of the grown crystal is up to the dimension of 29×19×5 mm 3 .The structure of the crystal was analyzed by single crystal X-ray diffraction and the functional groups present in the sample were identified by FTIR spectral analysis in the range 4000-450 cm -1 . The UV-vis-NIR studies was undertaken to find the transmittance in the ultraviolet and visible region. The efficiency of second harmonic generation was analyzed by Kurtz-Perry powder technique and compared with standard KDP crystal. Thermogravimetric and differential thermal analysis have been performed to determine the thermal stability of the crystal. Dielectric properties such as dielectric constant and dielectric loss were studied at various temperatures and frequencies. Vickers microhardness testing was carried out on the as grown crystal surface to reveal the mechanical properties of the crystal. Etching studies were made on the as grown crystal to analyze the structural imperfection of the crystal. Copyright © 2016 VBRI Press.

A phenomenological model for improving understanding of the ammonium nitrate agglomeration process

Ammonium nitrate is intensively used as explosive in the mining industry as the main component of ANFO. The ammonium nitrate is known to be a strong hygroscopic crystal matter which generates problems due to the creation of water bridges between crystals leading later to nucleation and crystallization forming an agglomerated solid cake. The agglomeration process damages the ammonium nitrate performance and is undesirable. Usually either organic or inorganic coatings are used to control agglomeration. In the present work a characterization method of humidity adsorption of the ammonium nitrate crystal was performed under laboratory conditions. Several samples were exposed into a defined humidity in a controlled chamber during 5 hours after which the samples were tested to measure agglomeration as the resistance force to compression. A clear relation was found between coating protection level, humidity and agglomeration. Agglomeration can be then predicted by a phenomenological model based of combination of the mono-layer BET adsorption and CNT nucleation models.

Shape‐Controlled Preparation of Basic Bismuth Nitrate Crystals with High Iodide‐Removal Capacities

AbstractBismuth compounds have generated much interest as agents for the removal of radioactive iodine. In this work, we present the shape‐controlled preparation of basic bismuth nitrate crystals (BBN) in the form of Reuleaux triangles, hexagons, and deformed hexagon disks. Shape control was achieved through modulation of the effect of the shape‐directing agent 2,3‐bis(2‐pyridyl)pyrazine (dpp). The crystals were shown to be capable of iodide removal through reaction with I− to form BiOI. Depending on the degree of saturation, the resultant solids can exhibit colors ranging from yellow (unsaturated) to orange (saturated). Sedimentation of the products facilitates its removal after use. While the removal capacities did not depend on the crystal morphology, the Reuleaux triangle disks exhibited faster reaction rates than the other two shapes. With improved removal capacities of up to 3.6 mmol g−1, fast removal kinetics, good selectivity, and capture irreversibility, the BBN crystals show good potential as agents for radioactive iodine removal.

Hygroscopicity of internally mixed multi-component aerosol particles of atmospheric relevance

The hygroscopic properties of two water-soluble organic compounds (WSOCs) relevant to urban haze pollution (phthalic acid and levoglucosan) and their internally mixtures with inorganic salts (ammonium sulfate and ammonium nitrate) are investigated using a hygroscopicity tandem differential mobility analyzer (H-TDMA) system. The multi-component particles uptake water gradually in the range 5-90% relative humidity (RH). The experimental results are compared with the thermodynamic model predictions. For most mixtures, Extended Aerosol Inorganic Model (E-AIM) predictions agree well with the measured growth factors. The hygroscopic growth of mixed particles can be well described by the Zdanovskii-Stokes-Robinson (ZSR) relation as long as the mixed particles are completely liquid. ZSR calculations underestimate the water uptake of mixed particles at moderate RH due to the partial dissolution of ammonium sulfate in the organic and ammonium nitrate solution in this RH region. The phase of ammonium nitrate in the initial dry particles changes dramatically with the composition of mixtures. The presence of organics in the mixed particles can inhibit the crystallization of ammonium nitrate during the drying process and results in water uptake at low RH (RH < 60%). These results demonstrate that certain representative WSOCs can substantially influence the hygroscopicity of inorganic salts and overall water uptake of particles. (c) 2015 Elsevier Ltd. All rights reserved.

Comparative Study of Nonlinear Semi-Organic Crystals: Glycine Sodium Nitrate

Glycine Sodium Nitrate (GSN) crystals were grown using slow evaporation technique at ambient temperature. Good quality crystals were obtained in the time interval of 5-6 weeks. Energy Dispersive X-ray Analysis (EDAX) and CHN analysis were carried out to check the purity of the grown crystals. Surface morphologies, smoothness and defects were observed by scanning electron microscope. GSN crystals were characterized by powder X-ray diffraction and indexing was done based on monoclinic system. UV-Vis study of the crystals showed that there is a wide range of transparency in the visible region. We also studied Raman and Fourier transform infrared spectra of GSN crystals. The results and their implications are discussed in the paper in detail.

Comparative Study of Nonlinear Semi-Organic Crystals: Glycine Sodium Nitrate

Glycine Sodium Nitrate (GSN) crystals were grown using slow evaporation technique at ambient temperature. Good quality crystals were obtained in the time interval of 5-6 weeks. Energy Dispersive X-ray Analysis (EDAX) and CHN analysis were carried out to check the purity of the grown crystals. Surface morphologies, smoothness and defects were observed by scanning electron microscope. GSN crystals were characterized by powder X-ray diffraction and indexing was done based on monoclinic system. UV-Vis study of the crystals showed that there is a wide range of transparency in the visible region. We also studied Raman and Fourier transform infrared spectra of GSN crystals. The results and their implications are discussed in the paper in detail.

Structural and vibrational spectral studies on hydrogen bonded salts: 4-chloroanilinium maleate and nitrate

In the present study, proton transfer from nitric and maleic acids to amine group (4-chloroaniline) led to hydrogen bonded crystals of 4-chloroanilinium maleate (4CAM) and 4-chloroanilinium nitrate (4CAN) which are investigated by the experimental and theoretical approaches. The molecular structures of these two compounds were optimized with the Density Functional Theory (DFT) using B3LYP function and the Hartree-Fock (HF) level with a6-311 ++G(d,p) basis set. Geometrical parameters of the molecules were also analyzed along with their intermolecular hydrogen bond, which tailors the ions. These analyses show that present molecules are stabilized through the N–H ⋯O and O–H ⋯O hydrogen bonds. The vibrational modes were computed by quantum chemical methods. Further, these modes are investigated by FT-IR and FT-Raman spectroscopy in the range of 4000–400 cm−1. The optimized molecular geometry and computed vibrational spectra are compared with experimental results, which show significant agreement. The natural bond orbital (NBO) analysis was carried out to interpret hyperconjucative interaction and intramolecular charge transfer (ICT). This analysis gives the precise insight into the nature of H-bond interactions. The chemical hardness, electronegativity and chemical potential of the molecules were determined by HOMO–LUMO plot. The frontier molecular orbitals have small band gap value, which signify the possible biological/pharmaceutical activity of the compounds. The proton transfer from the nitric and maleic acids to amine group (of 4-chloroaniline) lead to hydrogen bonded crystals of 4-chloroanilinium maleate (4CAM) and 4-chloroanilinium nitrate (4CAN). The molecular structures of these two compounds were optimized with the Density Functional Theory (DFT) and Hartree-Fock (HF) methods. Geometrical parameters of the molecules were analyzed along with their intermolecular hydrogen bond which tailors the ions. These analyses show that the molecular aggregations are stabilized through the N–H···O and O– H···O hydrogen bonds. The vibrational modes were computed by quantum chemical methods and further investigated by FT-IR and FT- Raman spectroscopy in the range of 4000–400 cm-1.

Reaction mechanism of lanthanum nitrate-doped Mo–La material during solid–liquid spray doping processing

At three critical temperatures which were obtained by thermo-gravimetry-differential thermal analysis–differential scanning calorimetry (TG/DTG/DSC) curves of lanthanum nitrate crystal, the air thermal decomposition experiments and solid–liquid spray doping simulation procedures of lanthanum nitrate crystal were carried out, and their products were analyzed by X-ray diffraction (XRD). Meanwhile, the spray doping processing of MoO2–50 wt% La(NO3)3 composite powder was undergone with lanthanum nitrate solution as the dopant, and doped MoO2 powder was analyzed by XRD. The results demonstrate that during the traditional solid–liquid spray doping processing, lanthanum nitrate, in the form of either crystal or aqueous solution, would be converted into La(NO3)3·4H2O by the dehydration reaction, rather than be decomposed to La2O3 and NO or NO2. Therefore, it is inferred that the oxynitride gas produced from the process is attributed to the decomposition of residual HNO3 in lanthanum nitrate crystal. The source of HNO3 is supported by the chemical composition of lanthanum nitrate crystal.

Optical, Thermal and Nonlinear Properties of Tristhiourea Lanthanum Nitrate

The single crystals of tristhiourea lanthanum nitrate (TTLaN) have been grown by solution growth using slow evaporation technique. The optical study revealed that the crystal has high transmission with lower cut-off wavelength of 235.78 nm. The EDAX analysis confirmed the grown compound elements. The presence of functional groups was identified through Fourier transform-infrared technique. The thermal stability of the crystal was determined from thermo gravimetric and differential thermal analysis curve. The second harmonic generation behavior of TTLaN crystal was tested by Kurtz-Perry powder technique. This single novel semiorganic crystal of TTLaN showed very good optical transmission property, high thermal stability and large non-linearity nature.

Potassium nitrate crystallization from microemulsions of Tergitol NP-4 and AOT in decane

The influence of the KNO3 concentration and the temperature, time, and crystallization method on the size and morphology of KNO3 powders prepared from reverse micellar solutions of the surfactants (Tergitol NP-4 and Tergitol NP-4 + AOT) in decane by isothermal mass crystallization was studied. In spite of the coincidence of the characteristics of the initial microemulsions (hydrodynamic diameter of micelles, interfacial tension, water and salt concentrations), the addition of AOT enhances the dispersion of the powders. The growth of the particle size is observed when the evaporation temperature increases from 35 to 45 °C. The control of the KNO3 content in the microemulsions made it possible to determine reliably the amount of the salt that became solid at different stages of crystallization.

Anisotropic terahertz dielectric responses of sodium nitrate crystals

Terahertz (THz) spectroscopy has become an effective tool to characterize the low-frequency rotational and vibrational modes of molecules. In addition, novel THz dielectric responses and optical properties on the basis of molecular rotation and vibration have attracted lots of attention because of their potential application in THz devices. In this paper, the dielectric response of low-symmetric sodium nitrate crystals in the frequency range of 0.2-1.5 THz was experimentally demonstrated. Four absorption bands at 0.23, 0.47, 0.92, and 1.15 THz were observed in the dielectric spectra and were tentatively ascribed to the rotational motion of nitrate ions. Based on the molecular rotation mechanism, the dielectric anisotropy and dielectric resonance of the crystal were discussed in detail.