Dongchul Choi

Characteristics of Indium Tin Oxide (ITO) Nanoparticles Recovered by Lift-off Method from TFT-LCD Panel Scraps

In this study, indium-tin-oxide (ITO) nanoparticles were simply recovered from the thin film transistor-liquid crystal display (TFT-LCD) panel scraps by means of lift-off method. This can be done by dissolving color filter (CF) layer which is located between ITO layer and glass substrate. In this way the ITO layer was easily lifted off the glass substrate of the panel scrap without panel crushing. Over 90% of the ITO on the TFT-LCD panel was recovered by using this method. After separating, the ITO was obtained as particle form and their characteristics were investigated. The recovered product appeared as aggregates of particles less than 100 nm in size. The weight ratio of In/Sn is very close to 91/9. XRD analysis showed that the ITO nanoparticles have well crystallized structures with (222) preferred orientation even after recovery. The method described in this paper could be applied to the industrial recovery business for large size LCD scraps from TV easily without crushing the glass substrate.

Hypereosinophilia Presenting as Eosinophilic Vasculitis and Multiple Peripheral Artery Occlusions without Organ Involvement

We report here a case with hypereosinophilia and peripheral artery occlusion. A 32-yr-old Korean woman presented to us with lower extremity swelling and pain. Angiography revealed that multiple lower extremity arteries were occlusive. The biopsy specimen showed perivascular and periadnexal dense eosinophilic infiltration in dermis and subcutaneous adipose tissue. Laboratory investigations revealed a persistent hypereosinophilia. She was prescribed prednisolone 60 mg daily. Her skin lesion and pain were improved and the eosinophil count was dramatically decreased. After discharge, eosinophil count gradually increased again. Cyanosis and pain of her fingers recurred. She had been treated with cyclophosphamide pulse therapy. Her eosinophilia was decreased, but the cyanosis and tingling sense were progressive. The extremity arterial stenoses were slightly progressed. Skin biopsy showed perivascular eosinophilic infiltration in the dermis and CD40 ligand (CD40L) positive eosinophilic infiltration. The serum TNF-α was markedly increased. These results suggest that CD40L (a member of TNF-α superfamily) could play a role in the inflammatory processes when eosinophil infiltration and activation are observed. We prescribed prednisolone, cyclophosphamide, clopidogrel, cilostazol, beraprost and nifedipine, and she was discharged.

Recovery of indium tin oxide (ITO) and glass plate from discarded TFT-LCD panels using an electrochemical method and acid treatment

The recovery of ITO and the glass substrate from discarded TFT-LCDs, without crushing the glass substrate, was done by using an electrochemical method and acid treatments. Anodic conditions did not show any redox reaction of the ITO except oxygen evolution. The oxygen evolution lifted the ITO layer off the glass substrate with the remaining colour filer and black matrix. Recovery of the ITO was 75%, but it showed an In–Sn ratio of 15.9:1. The recovered ITO was not suitable for reuse directly. It may be that it needed the addition of extra Sn. However, this work presented a new process for the resource circulation of the indium from discarded LCD panels. The free glass substrate was then recovered after removing the colour filter and black matrix by using an acid solution. The optical transmittance of the recovered glass substrate was about 90% in the visible region, and the average roughness was 0.96 nm.

Growth mechanism and photoluminescence properties of controlled PbWO4 micro- and mesocrystals obtained by the surfactant-assisted solvothermal method

In this paper, we report on the ortho-hexaclaval and size-controlled spherical PbWO4 micro- and mesocrystals synthesized by the surfactant-assisted solvothermal method with cationic surfactant cetyltrimethylammonium bromide (CTAB), deionized water or ethylene glycol solvents. The resulting hierarchical PbWO4 crystals were characterized by X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy and selected area electron diffraction. Experimental results indicated that CTAB played a critical role in the formation of specific structures. Finally, the optical properties were investigated at room temperature by means of ultraviolet-visible diffuse reflectance and photoluminescence measurements.

Nanodielectric properties of 16-MHDA self-assembled monolayers

A new type of potential organic nanodielectric was constructed by only 16-mercaptohexadecanoic (16-MHDA) self-assembled monolayers (SAMs). The tunneling effect through the mono- and multilayered 16-MHDA was explained with the Simmons tunneling model by measuring a metal–molecule–metal (M–M–M) sandwich device.

Recovery of ITO nanopowder from a waste ITO target by a simple co-precipitation method

A simple co-precipitation method was used to recover ITO as a nanopowder from the waste ITO target residue in sputtering chambers. The waste ITO target was dissolved in HCl and then ammonia solution was added to make indium tin hydroxide (ITO precursor). After heat treatment up to 400 °C for 6 h, the colour of the ITO precursor changed from white to yellow. The prepared ITO nanopowder was homogeneous with a size of 10 nm and a polycrystalline structure. Over 95 wt% of ITO was recovered using this method. The In/Sn weight ratio was estimated to be 10 : 1, which is very close to commercial ITO. We tried to scale-up the preparation procedure by 20 times to reduce the amount of acid for a more environmentally friendly approach. The particle size was about three times larger than that obtained from the small scale and the In/Sn ratio was slightly different. However, they were still close to commercial ITO.