Nitrides resonance structures

Major covalent nitrides include those of boron, sulfur, and phosphorus. Some indication of the nature of the phosphorus nitrides (the phosphazenes) was given in the last section. Boron nitrides have rather similar formulas but involve >77 77 B=N bonds instead of dir—pir P=N bonds. Figure 16.7 shows borazine, sometimes known as inorganic benzene. Note that two resonance structures are necessary to describe this molecule using valence-bond concepts. Experimentally, we find that all the B—N bonds have the same bond length, intermediate between that characteristic of single and double bonds. (Sulfur nitrides will be discussed in Chapter 17.)... 

The azides, except those of mercury) ), Hg(l,i, thalliura(l), 11(1), copper. Cu, silver, Ag, and lead, Pb, are readily prepared from hydrazoic acid and the oxide or carbonate of the metal, or by metathesis of the metal sulfate with barium azide. They are all thermally unstable, giving nitrogen and free metal or occasionally nitride. The azide ion appears to resonate between four structures ... 

On the transducer side, there have been more recent developments like the Lamb oscillator or the so-called film bulk acoustic resonators (FEAR). Lamb wave devices are related to SAW in terms of using interdigitated structures for transduction. The difference, however, is that in a Lamb wave resonator not only the surface, but the entire bulk of the device oscillates. This makes it much less sensitive against viscous damping. FEAR on the other hand consist of a metal/aluminium nitride/metal sandwich, where bulk waves (thickness oscillations) are induced in the AIN material. Eoth these devices have in com-... 

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