Abstract: This paper systematically analyzes the microstructural nonuniformity of ZnO varistors when
Al2O3 dopants are added. The introduction of Al2O3 dopants leads to a decrease of ZnO grain growth rate
and correspondingly an increase of the microstructural uniformity of ZnO varistors. Both the average
value and the standard deviation of ZnO grain sizes decrease with the increase of Al2O3 content,
approximately in a log-linear relation. With detailed experimental results, this study provides quantitative
references for the practice of adding Al2O3 dopants to give ZnO varistors desired microstructural and
Abstract: The effect of Ho2O3 doping on the electrical properties and microstructure of ZnO base varistor
was investigated. It was found that Ho2O3 is an effective dopant for increasing the breakdown electric
filed. The Ho2O3 doping can also improve the nonlinear performance both in low and high current area.
But excessive doping of Ho2O3 will decrease the withstanding surge current. With 0.8mol% Ho2O3
doping, the varistor samples exhibit a breakdown voltage of about 400V/mm, a nonlinear coefficient of 80
and the withstanding surge current of 8/20μs, waveshape is higher than 5kA. Ho2O3 dopant can hinder
ZnO grain growth and make the crystal grains more uniform.
Abstract: The numerical simulation is an effective method for researching the relationship between
macroscopic properties of ZnO varistors and their microstructural characteristics. However, the
computing efficiency is a big problem for further researches. In this paper, a quick piecewise linear
method for solving the complicated nonlinear resistor networks of ZnO varistors is proposed, which can
significantly improve the computing efficiency by a hundred times. The simulating models for the
microstructural characteristics of ZnO varistors are improved based on actual conduction mechanism of
grain boundaries. The simulations of more bulk characteristics of ZnO varistors become possible, such as
alternating current (AC) and surge properties.
Abstract: ZnO varistors with higher voltage gradients are expected in the power system, and the key to
this property is to diminish the grain size. In this paper, nano-sized ZnO particles are used as the raw
material in order to obtain small grains. Pellets are fabricated by two sintering methods: the conventional
pressureless sintering and the spark plasma sintering (SPS). For the samples fabricated by the
conventional sintering, the average grain size varies from 1 μm to more than 10 μm when the sintering
temperature changes from 900 oC to 1200 oC. The voltage gradient can reach as high as 2020 V/mm. The
grain size of the SPS samples is less than 1 μm, and the voltage gradients can reach 963 V/mm.
Abstract: Dense tin oxide based ceramics are a new type of varistor materials. To further understand the
electrical properties of SnO2 varistors doped with CoO, Nb2O5, and Cr2O3, the techniques of capacitancevoltage
(C-V) measurement and deep level transient spectroscopy (DLTS) were used to investigate the
electron traps in the SCN samples (doped with 1.0 mol% CoO and 0.05mol% Nb2O5) and SCNCr samples
(doped with 1.0 mol% CoO, 0.05mol% Nb2O5 and 0.05mol% Cr2O3). Two electron traps were detected:
trap T1 is located at Ec - 0.30 ± 0.01eV and trap T2 is located at Ec – 0.69 ± 0.03eV for both SCN and
SCNCr samples. The variations in the donor density and trap density could be related to the addition of
chromium oxide. The features of these traps are discussed based on the defect theory related to the SnO2
Abstract: Nanocrystalline thick-film gas sensor was fabricated by screen printing method with
CuO-doped tin oxide powder synthesized by hydrothermal method. Average grain size of the CuO-doped
tin oxide powders was typically below 10 nanometers and the thick-films had a narrow grain size
distribution typically below 50 nanometers. Effect of the amount of CuO on the sensing properties was
investigated and the optimal value was found to be 3 wt%. The nanocrystalline CuO-SnO2 thick-film gas
sensors were more sensitive to H2S than those based on commercial micro SnO2 powders, which were
attractive to the detection of low concentrations of H2S gas at relative low temperatures.
Abstract: Co-doped tin oxide thin films were prepared using spin-coating method. Variation of doping
content on the magnetic property and optical property were measured. XRD and magnetic measurement
shows that Co solubility limit in SnO2 is less than 3%. When the doping content is lower than 3%, the
films show good optical transmittance. When the doping content is reached to 10%, the optical
transmittance became lower. When the solution is diluted, the optical transmittance drops more slowly.
Abstract: Multistep electrochemical anodization is an electrochemical experiment orderly conducting in
different electrolytes. In this paper, TiO2 nanotube arrays have been firstly anodic grown in aqueous
electrolyte (H3PO4/HF) and later anodic grown in organic electrolyte (glycerol/NH4F). Compared with
separately anodizing in aqueous and organic electrolyte, the morphology of the resulting nanotube arrays
can be optimized. SEM images showed that the obtained nanotubes have a length of more than 2 μm and
single-pore diameter ranging from 120 to 150 nm. The current work indicates that the multistep electrochemical
anodization has a contribution to the optimization of the morphology of TiO2 nanotube arrays.
Abstract: The self-organized nanotube arrays were fabricated in glycerol electrolyte containing different
additives, such as deionized water or ethylene glycol. The effects of anodization conditions, including
anodic voltage, electrolyte viscosity, additives and ion concentration on the pores size and morphology
were studied. Combined with preoxidation process, high aspect ratio titania nanotube arrays were formed
rapidly in glycerol and saturated NaF solutions at 60 V for 1 h. SEM observation showed that a film with
the thickness of about 10μm was obtained. A possible mechanism of the nanotubes growth was presented.
Abstract: Thin Mn2(NO3)2/PVA precursor nanowire was fabricated via electrospinning technology at a
low temperature in this paper. After dried at 150°C for 10 hours and then sintered at 450°C for 2 hours,
Mn2O3 nanowire was successfully obtained. The nanowire was characterized using X-ray diffraction and
scanning electron microscopy. The results showed that the nanowire was composed of pure Mn2O3 phase.
The nanowire exhibited smooth surface and continuous sharp with length of tens of micrometer. The
diameter of Mn2O3 nanowire was measured and calculated through SEM, which showed most probable
value of about 110 nm and 270 nm. The reason of the diameter separation was also discussed.