Ren-Chuan Chang

Effects of the MnO additives on the properties of Pb(Fe2/3W1/3)-PbTiO3 relaxors : Comparison of empirical law and experimental results

In this paper, pure and 0.15wt%MnO additives of (1−x)Pb(Fe2∕3W1∕3)O3–xPbTiO3 [(1−x)PFW−xPT] with x=0.1, 0.2, 0.3, and 0.4 were synthesized by the conventional solid state reaction method. The dielectric diffusion properties were investigated with the empirical law. The lattice structure was found to transfer from tetragonal to pseudocubic and the diffusion phase characteristic is more notable as decreasing PbTiO3 compositions or adding MnO additives. Moreover, the dielectric loss is improved and the space charge polarization effect is vanished as adding MnO additives in 0.7PFW-0.3PT compounds. We suggested it was probably due to the lead vacancy which is substituted by the manganese ions or the interstitial manganese ions intervene into the interstice between the positive and negative ions.

Dielectric behaviors of Pb(Fe2∕3W1∕3)-PbTiO3 relaxors: Models comparison and numerical calculations

Regarding the dielectric characteristics of the diffusion phase transition (DPT) in ferroelectric relaxor materials, several researchers have provided similar but different laws to explain these phenomenon. These laws, presented by Burfoot et al. and Eiras et al., have been proven to provide a better explanation, especially the dielectric diffusion phenomenon, of the incomplete DPT materials if compared with the models presented by Smolensky, and Isupov. However, the differences in fitting adaptability and the physical and mathematical meanings between these two laws have never been discussed. In this paper, we analyze these two laws in the (1−x)Pb(Fe2∕3W1∕3)-xPbTiO3 [(1−x)PFW-xPT] relaxor system using the statistical regression theory. We find that the laws of both Burfoot and Eiras demonstrate the same adaptability and provide smaller estimation bias on the samples than the models of Smolensky and Isupov, despite the complete or incomplete DPT characteristics. When x is smaller, the samples tend to be c...

Improved Hole-Injection and Power Efficiency of Organic Light-Emitting Diodes Using an Ultrathin Li-Doped ZnO Buffer Layer

We report on the advantages of an anode buffer layer of Li-doped ZnO (LZO) on the electro-optical properties of organic light-emitting diodes (OLEDs). LZO layers with different thicknesses were prepared by thermally evaporating the LZO powders and then treating them with ultraviolet (UV) ozone exposure. The turn-on voltage of OLEDs decreased from 4 V (4.2 cd/m 2 ) to 3 V (5.1 cd/m 2 ), the maximum luminance value increased from 16780 to 28150 cd/m 2 and the power efficiency increased from 2.74 to 5.63 Im/W when a 1 nm thick LZO layer was inserted between indium-tin oxide (ITO) anodes and β-naphthylphenylbiphenyl diamine hole-transporting layers. X-ray and ultraviolet photoelectron spectroscopy were performed to show that the formation of the LZO layer and the work function increased by 0.64 eV when the LZO/ITO layer was treated by UV-ozone for 20 min. The surface of the LZO/ITO film became smoother after the UV-ozone treatment. Thus, the hole-injection energy barrier was lowered by inserting an LZO buffer layer, resulting in the decrease of the turn-on voltage and the increase of the power efficiency in OLEDs.

Dielectric Behavior of PFW-PT Relaxors: Model-Parameters Extraction

In this paper, we systematically present the physical and mathematical meanings of the parameters used in Burfoot et al.s and Eiras et al.s model. Based on our experimental results in (l-x)PFW-xPT relaxor system and the theoretically modelling results, it is shown that the parameter values in Burfoot et al.s model and Eiras et al.s model have not any variations after normalizing the maximum dielectric constant and shifting the temperature of the maximum dielectric constant Tm. It is also shown that the parameters in Eiras et al.s model have better physical and mathematical meanings.