Scott R. J. Oliver

A layered tin(II) phosphonate, [Sn(C6H5O3P)]n.

Poly[tin(II)-mu-phenylphosphonato], [Sn(C(6)H(5)O(3)P)](n), was synthesized solvothermally at 423 K and crystallized in the monoclinic system, space group Cc. The inorganic layers consist of alternating pyramidal Sn and tetrahedral P centers, joined by doubly bridging O atoms. The corner-sharing SnO(3) and PO(3)C(6)H(5) polyhedra define a corrugated layer of six-membered rings. The layers are connected along the unique b axis by interdigitated phenyl rings of the phenylphosphonate groups.

BING-2: a layered tin–oxalate potassium fluoride, KSn(C2O4)F

The title compound, KSn(C2O4)F, is a two-dimensional material related to our previously reported three-dimensional framework, Na4Sn4(C2O4)3F6. Both are alkali-metal tin–oxalate materials, but here the compound is layered and has potassium in place of sodium. The material was synthesized solvothermally at 423 K and crystallized in the monoclinic space group P21/c. The structure consists of potassium fluoride layers in the bc plane, which are sandwiched on both sides by tin–oxalate chains that extend along the c axis.

Characterization of Strain-Tolerant Ceramic/SAM Bilayer Coatings

Ceramic coatings can provide an ideal protection for MEMS (MicroElectroMechanical Systems) structures while imposing a great challenge in processing a prime, reliant coating due to their inherent brittleness and defects formed during processing. In an attempt to compensate for the weakness of the ceramic coating, we have developed a low-temperature solution precursor process to create strain-tolerant, protective bilayer coating consisting of an integrated ceramic-organic hybrid material. The top ceramic coating offers an inert, protective layer whereas the underlying nanometer scale self-assembled organic coating provides compliance for the overlying hard coating. Together, these bilayers minimize mechanical and thermal stresses. In addition, organic self-assembled monolayers(SAM) act as a ‘template’ by forming a proper surface functionality for the subsequent growth of hard ceramic coatings. Molecular level understanding of the microstructure and micromechanics involved in the synthesis and processing of the coating is systematically studied by a variety of characterization techniques such as XRD, AFM, SEM/EDS and nanoindentation. This work is also complemented by numerical simulation to provide a clearer understanding of the stress development in the ceramic coating and its interfacial properties.

Development of Protective Coatings for Silicon Devices

Ceramic coatings can be effectively used as a surface protective layer for silicon-based devices due to their inertness and good mechanical properties. One challenge is to avoid the weaknesses that ceramic coatings inherently possess, i.e., low strain tolerance, brittleness, high temperature required to process the film, and difficulty to produce a uniform, dense layer. Therefore, in an attempt to process strain-tolerant ceramic coatings at low temperatures, we develop an aqueous solution precursor processing route. Nanometer scale organic coatings, fabricated by self-assembly processes on the silicon, are used as a ‘template’ to aid the subsequent deposition of hard ceramic coatings (ZrO2 ). The ceramic coatings are deposited by spin coating. The organic self-assembled monolayer (SAM) coating provides temporary strain tolerance for the overlying hard coating upon mechanical and thermomechanical stresses before being decomposed at high temperatures. Molecular level understanding of the coating microstructure and micromechanics involved in the coating processes is systematically approached via experimental tools such as AFM and nanoindenter, as well as numerical simulation.Copyright

Solid State Synthesis and Characterization of Tin-Based Low-Dimensional Materials

We report the synthetic conditions, physical properties and potential applications of late group 14 metal (Sn) 0D, 1D, 2D and 3D extended materials. The structures are primarily neutral chain and anionic layered compounds. The latter are charge-balanced by ammonium cations, as in and BING-7 [Sn(C 2 O 4 )F - ] [NH 4 + ] and BING-8 [Sn(PO 4 H)F - ] [NH 4 + ]. The neutral layered compound and chain compounds BING-1 [Na 4 Sn 4 (C 2 O 4 )F 6 ], BING-2 [KSn(C 2 O 4 )F] and BING-4 [Sn(C 2 O 4 )(C 5 H 5 N)] have also been synthesized solvothermally. Thermogravimetric analysis (TGA) under nitrogen and in-situ variable temperature X-ray diffraction show that the materials decompose in the 200°C to 300°C range to more stable phases. Nuclear magnetic resonance (NMR) was used to monitor the ion-exchange properties of some of the materials. The intercalation properties of these materials are still being investigated.