Single crystals potassium

INTRODUCTION This data sheet contains information for single crystal potassium bromide. 

INTRODUCTION This data sheet summarizes properties of single crystal potassium chloride. 

The addition of potassium to Fe single crystals also enliances the activity for ammonia synthesis. Figure A3.10.19 shows the effect of surface potassium concentration on the N2 sticking coefficient. There is nearly a 300-fold increase in the sticking coefficient as the potassium concentration reaches -1.5 x 10 K atoms cm ... 

Bare S R, Strongin D R and Somoqai G A 1986 Ammonia synthesis over iron single crystal catalysts—the effects of alumina and potassium J. Phys. Chem. 90 4726... 

Anatase and mtile are produced commercially, whereas brookite has been produced by heating amorphous titanium dioxide, which is prepared from an alkyl titanate or sodium titanate [12034-34-3] with sodium or potassium hydroxide in. an autoclave at 200—600°C for several days. Only mtile has been synthesized from melts in the form of large single crystals. More recentiy (57), a new polymorph of titanium dioxide, Ti02(B), has been demonstrated, which is formed by hydrolysis of K Ti O to form 20, followed by subsequent calcination/dehydration at 500°C. The relatively open stmcture... 

A single-crystal x-ray diffraction study gives a stmctural formula of Na2 [B5 0g (0H)4]-3H2 0 and contains the pentaborate ion analogous to that found in the corresponding potassium compound (86). 

Mulliii, J.W. and Garside, J., 1967. Crystallization of aluminium potassium sulphate a study in the assessment of crystallizer design data I Single crystal growth rates, II Growth in a fluidised bed. Transactions of the Institution of Chemical Engineers, 45, 285-295. 

Figure 2.5. Potassium (a) and sodium (b) induced work function changes for adsorption at 100 K (open circles) and after annealing to 350 K or upon alkali adsorption at 350 K (open triangles) on Al single crystals.23 Reprinted with permission from the American Vacuum Society.

Figure 8.28. Ammonia rate for two types of iron single crystals (with and without promotion with potassium). [Adapted from D.R. Stongin and G.A. Somorjai,J. Catal. 109 (1988) 51.]...

When the potassium derivative was allowed to stand in ammonia, single crystals of the diammoniate K2[Zn(C2Fl)4]-2NFl3 63 separated.120 A low-temperature, single crystal X-ray analysis of 63 showed it to consist of tetrahedral [Zn(C2H)4]2 ions, which feature almost linear Zn-C-C units. The zinc-carbon bonds (2.053(3) A) are slightly longer than those in 64, while the carbon-carbon bonds are identical (1.203(4) A) in length. 

The catalytic properties of a surface are determined by its composition and structure on the atomic scale. Hence, it is not sufficient to know that a surface consists of a metal and a promoter, say iron and potassium, but it is essential to know the exact structure of the iron surface, including defects, steps, etc., as well as the exact locations of the promoter atoms. Thus, from a fundamental point of view, the ultimate goal of catalyst characterization should be to look at the surface atom by atom, and under reaction conditions. The well-defined surfaces of single crystals offer the best likelihood of atom-by-atom characterization, although occasionally atomic scale information can be obtained from real catalysts under in situ conditions as well, as the examples in Chapter 9 show. 

We begin with the structure of a noble metal catalyst. The emphasis is on the preparation of rhodium on aluminum oxide and the nature of the metal-support interaction. Next we focus on a promoted surface in a review of potassium on noble metals. This section illustrates how single crystal techniques have been applied to investigate to what extent promoters perturb the surface of a catalyst. The third study deals with the sulfidic cobalt-molybdenum catalysts used in hydrotreating reactions. Here we are concerned with the composition and structure of the catalytically active... 

Fig. 44. Single crystal-like I4N-ENDOR spectrum of metmyoglobin with B0 along gli temperature 2.1 K (Mb chromatog-raphically purified, 6 nM in 50% (v/v) glycerol, 0.1 M potassium phosphate buffer, pH = 6.0). (Adapted from Ref. 241)...

Fig. 22. A comparison of the rate of methane synthesis over a clean single crystal Ni(100) catalyst with the corresponding rate over a potassium-doped catalyst. Total reactant pressure is 120 torr, Hj/CO = 4/1. (From Ref. 148.)...

The sodium and potassium salts of 11 and 12 and their hydrates have been synthesized and characterized . The solid state structures of anhydrous potassium salt of 12 and its hydrate have been determined by single-crystal X-ray diffraction (Figure 21). Each structure has nearly planar N2O2 groups arranged as blades of a propeller around the main C-H axis. The three blades have similar helicities, or relative orientations. Helicity can be viewed as the relative orientation of the oxygen of the carbon-bound nitrogen with respect to the plane defined by the HCN atoms for the individual blades . ... 

Grayish-white metal hody-centered cubic crystalline structure density 19.3 g/cm3 melts at 3,422°C vaporizes at 5,555°C vapor pressure 1 torr at 3,990°C electrical resistivity 5.5 microhm-cm at 20°C modulus of elasticity about 50 to 57 x lO psi (single crystal) Poisson s ratio 0.17 magnetic sus-ceptibilty +59 x 10-6 thermal neutron absorption cross section 19.2 + 1.0 barns (2,200m/sec) velocity of sound, about 13,000 ft/sec insoluble in water practically insoluble in most acids and alkabes dissolves slowly in hot concentrated nitric acid dissolves in saturated aqueous solution of sodium chlorate and basic solution of potassium ferricyanide also solubibzed by fusion with sodium hydroxide or sodium carbonate in the presence of potassium nitrate followed by treatment with water... 

Small single crystals, such as those of potassium titanatc, are being used at an annual rate of over 10,000 tons for the reinforcement of nylon and other thermoplastics. These composites are replacing die-cast metals in many applications. Another microfiber, sodium hydroxycarbonate (Dawsonite), also improves the physical properties and flame resistance of many polymers. Many other single crystals, called whiskers, such as alumina, chromia, and boron carbide, have been used for making high-performance composites. 

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