Potassium Azide Research Articles

A Born Model Calculation of the Energies of Schottky Pair Formation and Cation Migration in Potassium Azide

AbstractCalculations are presented for the energy of Schottky pair formation and for the activation energy of cation vacancy migration in potassium azide (KN3). Parameters for the repulsive overlap energy of the azide molecule ion have been derived from a Born model treatment of the lattice interactions with the cohesive energy and its first and second derivatives used in the fitting procedure. Three different representations of the repulsive potential are considered. Point defect calculations are performed first in a rigid lattice approximation and then with the effects of polarization and relaxation included. The polarization energy is calculated by a generalized Mott and Littleton method, which accounts for the anisotropy of the lattice, in both zeroth and first order approximations. Relaxations include displacements and rotations of nearest neighbors of the defect configurations. The sensitivity of the results t o the choice of a repulsive potential are discussed.

Field Evaluation of Pesticides Applied to the Soil for Control of Insects and Nematodes Affecting Southern Peas in Georgia1

Soil fumigants DD® Mixture (dichloropropane-chloroproene mixture), DBCP (1,2-dibromo-3-chloropropane), and potassium azide (KN3), and nonvolatile pesticides aldicarb, carbofuran, disulfoton, duPont 1410 (methyl N, N -dimethyl- N' -l (methylcarhamoyl) oxy)-1-thio-oxamimidate), fensulfothion ( O, O -diethyl O-[p -(methyl-(methylsutinyl) phenyl hosphorothioate), and prophos ( O -ethyl S, S -dipropyl phosphorodithioate), were evaluated as soil treatments in 19170 and 1971 for control of plant parasitic nematodes and insects affecting southern peas, Vigna sinensis (Torner) Savi, in southern Georgia. In 1970 plots treated yield carbofuran had significantly taller plants, greater yield, and fewer plants infested with beet armyworms. Spodoptera exigua (Hubner), than other plots. Plants growing in plots treated with KN3 and DBCP were completely free of root galls caused by root-knot nematodes, Meloidogyne incognito (Kofoid & White) nematodes. Split applications of chemicals (1/2 replant and 1/2 postplant) were less effective than applications of the entire dosage of chemical preor post-plant. In 1971 control of thrips, Frankliniella spp. was best, and yield was highest in plots treated with aldicarb. Yield decreases in 1970 were correlated with terminal growth infested with beet armyworms (r = -0.71). In 1971 yield decreases were correlated with thrips injury (r = -0.52) and numbers of root-knot nematodes per 150 cc soil (r = -0.33).

Identification of Optical-Absorption Bands in uv-Irradiated Potassium Azide

The optical-absorption bands of uv-irradiated potassium azide are correlated with the electron-spin-resonance (ESR) spectra of previously identified defects by comparison of thermal annealing kinetics. The bands which peak at 580, 700, and 780 nm are attributed to the ${\mathrm{N}}_{4}^{\ensuremath{-}}$ defect, since their annealing kinetics are identical, with an activation energy of 0.92 \ifmmode\pm\else\textpm\fi{} 0.09 eV. The thermal conversion of the 565-nm band to the 580-, 700-, and 780-nm bands closely resembles that of the ${\mathrm{N}}_{2}^{\ensuremath{-}}$ defect to the ${\mathrm{N}}_{4}^{\ensuremath{-}}$ defect, and, accordingly, the 565-nm band is tentatively attributed to the ${\mathrm{N}}_{2}^{\ensuremath{-}}$ defect. The activation energy for the thermal conversion of the optical spectrum is 0.70 \ifmmode\pm\else\textpm\fi{} 0.05 eV. No ESR spectrum could be correlated with the 360-nm band, which annealed below 140K. All of the observed optical transitions are polarized perpendicular to the $c$ axis. Models are proposed for the electronic structure of ${\mathrm{N}}_{2}^{\ensuremath{-}}$, and of ${\mathrm{N}}_{4}^{\ensuremath{-}}$ in a rectangular conformation, which account qualitatively for the observed optical and ESR spectra.

Antibody plaque formation in vitro in the presence of respiration inhibitors.

The suppressive effects of 4 respiration inhibitors on <i>in vitro </i>antibody plaque formation to sheep erythrocytes by mouse spleen cells in agar gel was determined. Potassium cyanide, at a concentration of 10<sup>––</sup><sup>2</sup> m, and rotenone, at a concentration of 10<sup>––4</sup> m, markedly suppressed antibody plaque-forming cells (PFC) when added to the agar gel <i>in vitro. </i>In contrast, potassium azide, at a concentration of 10<sup>––2</sup> m showed a slight inhibition and thenoyltrifluoroacetone, at a 10<sup>––3</sup> m-concentration, showed no effect. Both cyanide and azide decreased the hemolytic titers of serum hemolysins at a 10<sup>––2</sup> m-concentration. All inhibitors had no effect on serum hemolysins at 10<sup>––3</sup> m-concentration or lower. These results support the concept that actual viability of antibody-forming cells is not necessary for hemolytic plaque formation <i>in vitro, </i>since only relatively large concentrations of respiration inhibitors, much greater than the dosages needed to inhibit cell metabolism, inhibited antibody formation.

Unstable intermediates. Part 111.—Electron spin resonance studies of γ-irradiated frozen aqueous solutions of alkali-metal azides

Aqueous glasses containing potassium or sodium azide at 77 K after exposure to 60Co γ-rays, had e.s.r. spectra containing features characteristic of NH2 radicals. Exposure to 2537 A light also gave NH2 radicals together with an isotropic 5 G triplet characteristic of nitrogen atoms. The NH2 radicals are probably formed from N2–3 or HN–3 by loss of nitrogen molecules and protonation of NH–. This occurs even in glasses containing 10 M alkali hydroxide.

Unstable intermediates. Part 118.—Gamma irradiated potassium azide: electron spin resonance spectra of N–4 and N2–3 radical ions

After exposure of potassium azide to γ-rays at room temperature both N–4 and N2–3 have been identified by e.s.r. spectroscopy. The latter has not previously been detected in this material, but features previously assigned to pairs of N–4 radicals are thought to be better identified with N2–3. This radical is thought to be bent, with a bond angle close to 139°. The e.s.r. parameters are compared with those for other, isoelectronic radicals.

Chemical effects of the nuclear reaction 14N(n,p)14C in potassium azide

Chemical effects of the nuclear reaction 14N(n,p)14C in potassium azide

Nitrification Inhibition in Soil: II. Evaluation of Anhydrous Ammonia‐Potassium Azide Solutions in Eastern Washington

AbstractThe effectiveness of potassium azide (KN3) as a nitrification inhibitor for field‐applied anhydrous NH3 was evaluated on a Naff silt loam in the winter wheat (Triticum aestivum L.) area of eastern Washington. Formulations of KN3 in liquid NH3 of 0, 2, and 6% (w/w) were applied to fallow soil in August 1969 at a rate of 112 kg N/ha (81‐cm spacing) with a special field applicator. The 2% formulation was also applied at a rate of 224 kg N/ha. The NH3 retention zone was sampled periodically through February 1970 and analyzed for NH4+‐N, NO2‐‐N, and NO3‐‐N. Both levels of KN3 were effective in reducing the nitrification rate during the early post injection period, but the higher level was more effective at later dates. Two months after application, the amounts of NO3‐‐N recovered from the retention zone as percent of total extractable N were 67, 48, and 36 for NH3 alone, NH3 + KN3 (2%), and NH3 + KN3 (6%), respectively. Percentage amounts of NO3‐‐N decreased with increase in N application rate. Nitrification inhibition due to KN3 was still evident 6 months after application, particularly at the high N rate. The inhibitory effect of low soil temperature during the winter months was also apparent. These results indicate that KN3 formulated with anhydrous NH3 was an effective nitrification inhibitor for this N source.

Nitrification Inhibition in Soil: I. A Comparison of 2‐Chloro‐6‐(trichloromethyl)pyridine and Potassium Azide Formulated with Anhydrous Ammonia

AbstractThe relative effectiveness of 2‐chloro‐6‐(trichloromethyl) pyridine and potassium azide as nitrification inhibitors, formulated and applied to soil with anhydrous NH3, was compared in laboratory and growth chamber experiments. At an inhibitor level of 10 ppm, and after 14 days, NH4+ concentrations 0 to 2.5 cm from the point of release of NH3, NH3 + KN3, and NH3 + N‐Serve were 695, 810, and 887 ppm N respectively, while after 56 days corresponding values had decreased to 129, 316, and 609 ppm N. After 14 and 56 days of incubation in unplanted pots, KN3 was 60 and 40%, respectively, as effective as N‐Serve in suppressing nitrification. N‐Serve was more effective than KN3 during longer incubation periods because of its greater residual activity.In general, yields of ryegrass (Lolium sp.) and cotton forage (Gossypium hirsutum L.) followed the order of NH3 = NH3 + KN3 > NH3 + N‐Serve. The greater residual activity of N‐Serve compared with KN3 and the absence of root development in the center of the NH3 + N‐Serve retention zone, as well as the stunted and flaccid appearance of roots, was indicative of potential phytotoxicity of N‐Serve in this particular mode of application.

Lattice Dynamics of Potassium Azide. A Group-Theoretical Analysis

The symmetry properties of normal modes of lattice vibrations of the lattice of potassium azide are investigated using the formalism of Maradudin and Vosko. Using a computer code, the symmetry vectors at several points of the Brillouin zone are determined. The interrelations between elements of the dynamical matrix corresponding to these points have also been obtained from the same code. This information has helped in developing a force model to analyze experimental results of neutron scattering studies made recently at this laboratory.

Compressibility of Inorganic Azides

The compressibility of α lead azide, β lead azide, barium azide, potassium azide, sodium azide, and thallium azide have been measured by single-crystal x-ray diffraction techniques for the first time in a new application of the diamond anvil pressure cell. Both the anisotropic and volume compressibilities are reported. The pressures were determined by measurements at the known freezing points of n-hexane and ethanol. A phase transition occurs in thallium azide at a pressure between the freezing points of chloroform (5390 bar) and n-decane (2990 bar). Pressure–temperature observations in the diamond cell of lead azide were carried out to 300°C and approximately 30 kbar. No phase transitions were observed. Radiation damage to azide crystals under high pressures is reduced significantly.

Behavior of Potassium Azide in the Soil

Potassium azide (KN3) was shown to have potential use as a soil fumigant based on the evidence that azide killed dormant seeds in laboratory and field experiments. Volatility was an important factor in the dissipation of KN3; an acid environment greatly increased volatility probably due to rapid conversion to HN3, whereas soil type exerted little influence on vapor loss. Increasing the soil moisture decreased volatility due to water solubility of NH3. KN3 was leachable and weakly adsorbed in various soil types and at different pH levels. From experiments using stoppered flasks to exclude volatility, it was concluded that the dissipation of KN3 was a chemical phenomenon accelerated by elevated temperatures. KN3 dissipated rapidly from an acid soil whether autoclaved or non-autoclaved; however, alkaline soils prevented dissipation of KN3. Apparently, KN3 is converted to HN3 before it is decomposed. Diffusion within the soil was restricted and occurred only in an acid soil. Covering the soil with plastic immediately after application reduced volatility and increased the biological activity of KN3.

Potassium Azide as a Nitrification Inhibitor1

AbstractThe effect of 0, 2, 4, 8, 16, and 32 ppm KN3 on nitrification in soil was studied at 30 and 10 C. At both temperatures, KN3 was an effective nitrification inhibitor. At 30 C, 75 ppm of added NH4 + disappeared in 2 weeks where no KN3 had been added as compared to 4 weeks at the 32 ppm KN3 rate. At 10 C, 4 weeks were required for the NH4+ to disappear at 0 ppm KN3, whereas more NH4+ was present after 18 weeks than initially where 32 ppm KN3 was applied. Concentrations of (NO2‐ + NO3‐)‐ N were found to be similar at all KN3 rates once the NH4+ had disappeared. This indicates that KN3 had no effect on mineralization‐immobilization relationships. The soil pH for both incubation temperatures was 6.8.The effect of 4 ppm KN3 in soil incubated at 30 C was studied at soil pH levels of 4.5, 6.0, and 7.5. The NH4‐N and (NO2‐ + NO3‐)‐N concentrations during 4 weeks incubation indicated that KN3 did not inhibit nitrification at soil pH levels of 4.5 and 6.0 but that nitrification was inhibited at pH 7.5. At 30 C, KN3 does not appear to be an effective nitrification inhibitor for soils of pH less than 6.0.

Exchange coupled paramagnetic molecular ions in ultraviolet irradiated potassium azide

The electron spin resonance spectra of uv irradiated KN 3 indicates that exchange coupling is occuring between some of the radicals that are produced.

Growth of single crystals of potassium azide (KN 3) from the melt

The growth of pure and doped single crystals of potassium azide of cm size is reported. Problems encountered are discussed and practical solutions indicated.

Respiration of sugarbeets following harvest in relation to temperature, mechanical injury and selected chemical treatment

The loss of sugar from sugarbeets during storage is a sIg­ nificant economic factor. Some factors which contribute to this post-harvest loss include dehydration, decay, mechanical injury, sprouting, freezing, respiration and sugar conv~rsions. Although quite variable, sugar losses alone have been estimated (6)3 at approximately I pound of sugar per ton of beets per day over the normal processing period, which may be as long as 4 montbs following harvest. Another es timate (2) places the average loss at more than 40 pounds of sugar per ton of beets pi led, excluding processing loss. There is , therefore, great interest within the beet sugar industry to minimize this loss by improving the handling and storage techniques. Accurate assessment of the various factors contributing to the overall loss is of paramount importance in order to determine where improvement should be made, if proven economically feasib le. Knowledge of sugarbeet respiration and factors which in­ fluel1Ce its magnitude may be of value in developing improved handling and storage techniques. This study was initiated to determine the influence of temperature, mechanical injury and selected chemicals on the respiration rate of sugarbeets. Materials and Methods The sugarbeets (variety GW H-l ) employed in these studies were grown near Fremont, Ohio. They were harvested on October 16 and November 6, 1967. Those from the first harvest were subjected to post-harvest chemical treatments, mecharii cal injury and ethylene treatment. Beets from the second harvest were employed for storage temperature and mechanical injury studies. The beets for both studies upon harvest were topped manuall y (cut just below the crown), a nd cleaned by a high pressure water spray to remove the adhering soil. The chemica l treatment study consisted of 4 lots of approximately 30 beets each, fairly uniform in size, which r eceived a IS-s econd immersion in one of the following treating solutions: 1) potassium azide - a res­

DC Ionic Conductivity of Potassium Azide

AbstractThe electrical conductance of both single crystal and pressed pellets of potassium azide has been measured. The ionic conductance parameters of KN3 were calculated from samples containing known amounts of Ba2+ ion impurity. The conventional theory of association was found to be adequate to describe association between Ba2+ and cation vacancies. A value of 0.2 eV was determined for — ζ, where ζ is the free energy of association of complexes. The following point defect parameters were determined: h, the enthalpy change for the formation of a defect pair = 1.25 eV, Δh, the enthalpy for migration of a cation vacancy = 0.76 eV, s, the entropy change on the formation of a defect pair = 0.119 × 10−3 eV deg−1. Equations describing X0, the number of thermally produced defects in a pure crystal, and μ, the mobility of the cation vacancy, both as a function of temperature have been derived.

Ionic Conductance of Potassium Azide in the Solid State

New experimental results on the dc electrical conductance, between room temperature and 250°C, of potassium azide single crystals and pellets and potassium azide doped with barium azide are described. These data have been interpreted as involving cation current carrying species. Numerical values for the enthalpy of migration and enthalpy of defect pair formation are deduced. These are, respectively Δh1=0.79±0.05 and h=1.43±0.05. Isothermal dc conductance data are also presented and imply that the charge carriers are involved in the thermal decomposition processes of KN3.

Thermoluminescence of potassium azide

Thermoluminescence measurements on potassium azide (KN3), using both x-ray or gamma-ray irradiations, indicate that there are many shallow charge trapping levels. In the temperature range from 10-525 °K a typical sample will have twelve glow peaks and trap depths range from 0·045-0·6 ev. In contrast, ultraviolet light irradiation produces only the three glow peaks at 46, 70 and 80 °K. The glow peaks at 109, 123, 142 and 175 °K continue to occur after the sample has been repeatedly irradiated and heated. However, the peaks at 211, 225 and 245 °K disappear irreversibly after a few irradiation and heating cycles. In addition to the results on `pure' crystals described above, measurements were made on samples containing various amounts of Ca2+, Ba2+, Sr2+ and SO42- ion impurity. The data from these doped samples suggest that the 123 °K peak is associated with a hole-trapping centre which could be the azide analogue of the Vk centre observed in alkali halides. The thermoluminescence results, coupled with other information, give some information about other defects.

Lattice vibrations in alkali azides

The longwavelength lattice vibrations in potassium, rubidium and caesium azides have been calculated using Born's lattice dynamics.