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Brass is among the utility metals for daily life. We present an easy corrosion experiment for demonstration in high school or first-year undergraduate studies. Almost any kind of brass can be dezincified in 1 m hydrochloric acid. Copper as the noble component remains as salmon pink coating on the workpiece while zinc and lead, the latter being a frequent minor alloying component of brass, are dissolved. Lead can be detected as PbS (in-situ generation of H2S from a splinter of FeS or as PbI2 using KI). Zinc can be analyzed as Rinmann's green or via a microchemical drop reaction with dithizone. [ABSTRACT FROM AUTHOR]

The optical control of millimeter waves in image guides composed of a quartz-silicon sandwich structure is investigated for use at W-band frequencies. The controllability of the dispersion characteristics is confirmed both theoretically and experimentally for single-moded guides using a pulse-modulated high-power semiconductor laser source. For the first time, measurement results of the frequency response of the phase shift are presented and, in addition to top side illumination, lateral illumination of the image guide is investigated. Differences between experimental and theoretical data based on a one-dimensional diffusion-controlled nonuniform plasma layer model are attributed to an inhomogeneity of the plasma distribution along the broadside of the silicon strip due to the impact of a huge surface recombination at the cutting area of the silicon strip. Index Terms--Image guide, millimeter-wave phase shifter, millimeter-wave photonics, optical control.

Single crystals of the high-temperature modification of RhSn4 were obtained from a tin flux (1:20 molar ratio; final annealing at 920 K; dissolution of the tin matrix in 2N HCl). The structure was refined from single-crystal X-ray diffractometer data: I41/acd, a=629.73(5), c=2288.36(18) pm, wR2=0.0382, 447 F2 values and 14 variables. β-RhSn4 is isotypic with β-IrSn4. The rhodium atoms have slightly distorted square-antiprismatic tin coordination with Rh–Sn distances of 4×273.4 and 4×274.1 pm. The RhSn8 units are condensed via common edges to layers that are staggered with respect to each other and stacked in ABCD sequence. A 119Sn Mössbauer spectroscopic characterization of ß-RhSn4 and the stannides RhSn3 and α-RhSn4 shows the typical isomer shifts for transition metal stannides. Only for α-RhSn4 the three crystallographically independent tin sites could be resolved, a consequence of the different s-electron density. Treatment of α-RhSn4 under high-pressure (up to 10 GPa)/high-temperature (up to T=1370 K) conditions leads to decomposition into Rh1.5Sn, RhSn2 and β-Sn. [ABSTRACT FROM AUTHOR]

The YCrB4 type borides YTB4 (T = Mo, W, Re) were synthesized from the elements by arc-melting and subsequent annealing. The structures were refined from single crystal X-ray diffractometer data: Pbam, a = 602.84(8), b = 1164.5(1), c = 361.20(4) pm, wR2 = 0.0404, 624 F2 values, 26 variables for YMoB4, a = 603.00(7), b = 1165.1(1), c = 360.63(6) pm, wR2 = 0.0487, 474 F2 values, 26 variables for YWB4, and a = 596.67(6), b = 1154.4(1), c = 360.21(4) pm, wR2 = 0.0465, 544 F2 values, 26 variables for YReB4. The boron atoms build up planar networks which are a tessellation of slightly distorted pentagons and heptagons. Adjacent networks coordinate the transition metal and yttrium atoms in the form of pentagonal and heptagonal prisms, respectively. The four crystallographically distinct boron sites are differentiated by high-resolution 11B solid state isotropic magnetic shifts and nuclear electric quadrupolar coupling constants. Partial site assignments are possible based on comparisons with electric field gradient calculations using the WIEN2k code. 89Y MAS NMR spectroscopic studies suggest substantially weaker Knight shift contributions to the resonance frequencies when compared to other intermetallic yttrium compounds, including other ternary yttrium boride compounds measured previously. [ABSTRACT FROM AUTHOR]