Pulsed laser ablation has been used to deposit thin films of SrFeO25+x (x = 0 to ≈0.5). Previous work has shown that the orientation of the films, determined by powder x-ray diffraction depended strongly upon the deposition temperature. Films grown below 770 K showed little or no orientation. A growth temperature of 900 K resulted in films oriented (200). Growth temperatures of > 1000 K produced films oriented predominantly (110). At 673 K in an oxygen atmosphere, oriented films readily converted from the oxygen deficient brownmillerite form (x=0) to the oxygen rich cubic (or distorted cubic) perovskite form (x≈0.3). Films which exhibited no initial orientation did not react with oxygen under these conditions. Cycling non-oriented films between 230 and 800 ppm of oxygen in 101.3 kPa of nitrogen at 673 K resulted in weak (110) orientation. Once oriented, the films reacted readily with oxygen and exhibited measurable resistance changes. The conversion from oxygen deficient to oxygen rich form was monitored by x-ray diffraction and the DC resistance of the films.

We present a novel virtual multi-probe scanning system and a new error separation method for the exact optical profile reconstruction. The system realized the multi-probe function by a single probe that fixed on a flexible hinge stage. The flexible hinge stage has a millimeter-level travel range and driven by a voice coil motor to realize the function of the multi-probe. In this work, a high accuracy profile measurement with a high lateral resolution is realized under the errors of the straightness, zero-adjustment, and yaw. The new method can obtain multiple sets of straightness error of the guideway in one scanning measurement. This novel virtual multi-probe scanning system and its corresponding method has the following benefits: (i) using a single probe to separate straightness error without reversal, and can accurately reconstruct the profile, (ii) the reconstructed profile has a very high lateral resolution, depending on the lateral resolution (μm level) of the probe, (iii) the cumulative amplification effect of zero-adjustment error can be eliminated by our method, (iv) the new method can obtain multiple sets of straightness error with higher reliability and accuracy compared with only one set. These benefits are proved by theoretical derivation and simulation. Experiments also prove that the new method can reconstruct the profile with high accuracy and lateral resolution.

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Thin films of a series of perovskites based on the general formula SrFeO, 5+x have been investigated for their suitability as oxygen sensing materials. When the films are exposed to oxygen of varying partial pressures at temperatures up to 670K, the bulk oxygen content, x, of the films changes and this is accompanied by significant changes in the film optical characteristics. These properties have been measured by transmission spectrophotometry in the uv-vis region using both batch and preliminary in-situ techniques. The data show a dependence of optical transmission on the perovskite oxygen stoichiometry, and a relationship to oxygen composition in the gas phase for sensor response.The perovskites ABO,,,, which have a wide range of oxygen non-stoichiometry and which exhibit high 0, lability at moderate temperatures, ( T < 750K), are suitable candidates for providing oxygen sensing materials. SrFeQ, 5+x has these favourable properties with a range of composition between the oxygen poor and oxygen rich forms approaching x = 0.5. There are four structural phases over this range, [ 1-31; three of order-disorder type based on a distorted-cubic perovskite lattice, and one of orthorhombic brownmillerite type. All of these phases show fast, reversible uptake of 0,at T > 550K, [3], and accompanying this reaction with oxygen are changes in several associated physical properties, [4]. The modification of the optical characteristics of the films are an example of the type of property which is of interest. Thin-films of SrFeO, 5+x are yellow and transparent in the brownmillerite (x s 0) form, and become progressively darker and more optically opaque with increasing x, [5 1. The work reported here describes the study of this process using thin-films of SrFeO, 5+x deposited onto sapphire substrates by pulsed laser ablation. The optical transmission of the films in the uv-vis region of the spectrum has been measured using a batch method. The design and construction of a glass gas-flow cell to facilitate in-situ measurements of transmittance at temperatures up to T s 700K is also described.The parent perovskite, SrFeO,,,, and pellets of this composition for use as targets in the film deposition step were prepared in a tube furnace by thermal treatment and sintering under flowing oxygen or argon as described earlier [ 3 ] . X-ray diffraction was used to confirm the product as single phase. The thin-films of either SrFeO, , or SrFeO-, were grown onto (1102) sapphire substrates by pulsed laser ablation-deposition, (PLD), using an excimer laser operating with Kr/F giving 248nm radiation. The films, approximately lcm x 2cm and ranging in thickness between 200-300nm, were grown on heated substrates in a stainless steel chamber which allowed a controlled atmosphere exposure. Other details of the PLD process are reported elsewhere, [6]. The optical transmittance, (T), of the films over the wavelength range 190 I A I 9OOnm was determined in a batch process using a Cary 1E spectrophotometer. A series of films was exposed to 0, at T = 670K...

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