Effect of transport agent boron triiodide on the synthesis and crystal quality of boron arsenide

Cubic boron arsenide(BAs)has attracted great attention due to its high thermal conductivity,however,its controllable,stable,and ideal preparation remains challenging.Herein,we investigated the effect of iodine-containing transport agents I_(2) and boron triiodide(BI_(3))on BAs synthesized and grown through chemical vapor transport.Results show that similar to the commonly used I_(2),BI_(3) accelerates the synthesis and improves the mass fraction of BAs from ~12% to over 90% at 820℃ and 1.5 MPa,a value beyond the promoting effect of only increasing temperature and pressure.Both agents enhance the quality of BAs crystals by reducing the full width at half maximum by up to 10%-20%.I_(2) agglomerates the grown crystals with twin defects(~50 nm wide),and BI_(3) improves the crystal anisotropy and element uniformity of BAs crystals with narrow twins(~15 nm wide)and increases the stoichiometry ratio(~0.990)to almost 1.Owing to the boron interstitials from the excessive boron supply,the spacing of layers in {111} increases to 0.286 nm in the presence of I_(2).Owing to its coordinated effect,BI_(3) only slightly influences the layer spacing at 0.275 nm,which is close to the theoretical value of 0.276 nm.In the chemical vapor transport,the anisotropic crystals with flat surfaces exhibit single-crystal characteristics under the action of BI_(3).Different from that of I_(2),the coordinated effect of BI_(3) can promote the efficient preparation of high-quality BAs crystal seeds and facilitate the advanced application of BAs.

Model-based Tracking for Agent-based Control Systems in the Case of Sensor Failures

The study on artificial intelligence(AI) methods for tuning of particle accelerators has been reported in many literatures.This paper presents tuning method for agent-based control systems of transport lines in the case of sensor/actuator failures.The method uses model-based tracking concept to relax the demand on sensor data.The condition for successful operation of the stated scheme is derived,and the concept is demonstrated through simulation by applying it to the model of microtron,transport line-1 and booster of indus accelerator.The results show that this approach is very effective in transport line control during sensor/actuator failures.