Tin IV Oxide and Related Materials

Tin (IV) oxide, Sn02, (rutile-type structure), a well-established n-type semiconductor with a wide band gap ( gap = 3.6 eV at 300 K) also has potential applications as a catalyst support,as transparent conducting electrodes,and as a gas sensor.i This material possesses many advantages, such as (i) high thermodynamic stability in air (at least up to 500 °C), (ii) low cost, and (iii) the possibility of the introduction of catalysts or dopants to enhance the sensitivity or selectivity.  

Tin(II) f-butoxide, [(Sn(O-Bu02)2l, as well as the corresponding heterometal alkoxides [M Sn(0-BuOsjz] (M = Ca, Sr, Ba), have been employed as precursors for chemical vapor deposition processes, generating either Sn02 or MSnOs (M = Ca, Sr, Ba).  

Thin films of Pt-doped-Sn02 have been deposited in the temperature range 320 0 °C by MOCVD, using SnEt4 and Pt(hfa)2 hfa = hexafluoroacetylacetonato in an O2 atmosphere. This material was much more sensitive than Sn02 for ethanol detection in dry air.  

In order to enhance conductivity and other properties, Sn02 has been doped with cations containing Sb, In, Cd, Bi, Mo, B, P, Te, or W and/or with F or Cl anions.  

Sn-doped In203 (ITO) is the most widely used transparent conducting oxide (TCO) material. This can be satisfactorily prepared by pyrolitic oxidation of a mixture of ln(dpm)3 and Sn(n-Bu)2(OAc)2 at 550 °C in a oxygen-nitrogen or nitrogen saturated with water vapor atmosphere, 6 [Equation (3.1.3) dpm = 2,2,6,6-tetramethyl-3,5-heptanedionate ]. 

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ITRI has developed and patented processes for preparing and utilizing stable aqueous colloidal sols of tin(IV) oxide and related materials. These products, which contain nanometer-scale particulate tin oxide, are useful precursors for the synthesis of ceramic bodies, powders, and coatings, and may And application in encapsulated pigments, electroconductive materials, catalysts, and transparent tin oxide Aims on glass and other substrates. 

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