Slow Scanning Speed Research Articles

Temperature evolution, phase ratio and corrosion resistance of duplex stainless steels treated by laser surface heat treatment

• Laser surface heat treatment (LSHT) was performed on duplex stainless steels 2304, 2205, and 2507. • The effect of laser spot size and cooling time t 12/8 was investigated by numerical simulation and microstructure analysis. • LSHT obtained the peak temperature, the t 12/8 and the effective depth as 1350 °C, 8.9 s and 1.5 mm respectively. • Austenite percentage increased from 2%, 5%, and 38% to 27%, 36% and 55 % respectively for 2304, 2205, and 2507. • LSHT increased the corrosion pitting temperature from 13, 42 and 66 °C to 19, 52 and 76 °C respectively for 2304, 2205, and 2507. Duplex stainless steels (DSS) are promising materials due to excellent corrosion resistance and good mechanical properties. However, the corrosion resistance of DSS welded joints deteriorates unavoidably due to the unbalanced phase ratio, namely a low austenite percentage resulted from the welding thermal cycle. Laser surface heat treatment (LSHT) exhibits tremendous advantages to restore the corrosion resistance especially regarding efficiency and flexibility. By adjusting laser energy input, including laser power and spot size, different LSHT conditions were applied to DSS 2304, 2205 and 2507, whose austenite content were deliberately decreased to a very low percentage. The temperature evolution during the LSHT was calculated out by finite element analysis. Critical pitting temperature (CPT) was measured to evaluate the corrosion resistance. A long length of laser spot and a slow scanning speed were beneficial for increasing the austenite percentage during the LSHT. With the length of laser spot as 100 mm and the scan speed as 2 mm/s, the laser power was adjusted to obtain a target peak temperature of 1350 ℃, which provided a cooling time t 12/8 as 8.9 s and an effective action depth as 1.5 mm. For DSS 2304 and 2205, the austenite percentage increased from 2% and 5% in deteriorated samples to 28 % and 56 % after the LSHT; the CPT increased from 12.5 and 42.3 ℃ to 19.2 and 51.8 ℃ respectively. DSS 2507 remained the highest austenite percentage after the same deterioration and exhibited the best corrosion resistance under all the used conditions. The influence of LSHT processing parameters and material compositions on the phase transformation and the corrosion resistance was discussed accordingly.

TrueEBSD: Correcting spatial distortions in electron backscatter diffraction maps

Electron backscatter diffraction (EBSD) in the scanning electron microscope is routinely used for microstructural characterisation of polycrystalline materials. Maps of EBSD data are typically acquired at high stage tilt and slow scan speed, leading to tilt and drift distortions that obscure or distort features in the final microstructure map. In this paper, we describe TrueEBSD, an automatic postprocessing procedure for distortion correction with pixel-scale precision. Intermediate images are used to separate tilt and drift distortion components and fit each to a physically-informed distortion model. We demonstrate TrueEBSD on three case studies (titanium, zirconium and hydride containing Zr), where distortion removal has enabled characterisation of otherwise inaccessible microstructural features.

Microwave Photonic Interrogation of a High-Speed and High-Resolution Temperature Sensor Based on Cascaded Fiber-Optic Sagnac Loops

A high-speed and high-resolution temperature sensor based on two cascaded fiber-optic Sagnac loops (FSLs) interrogated using a microwave photonic (MWP) method is proposed and experimentally demonstrated. In the proposed system, an FSL is used as a sensor element. When it is experiencing temperate change, its spectrum is shifted, which leads to the shift in the spectrum of the cascaded FSLs. Instead of measuring the wavelength shift of the spectrum by using an optical spectrum analyzer (OSA), which has a low wavelength resolution and a slow scanning speed, we convert the optical spectrum to the time domain based on spectral shaping and wavelength-to-time (SS-WTT) mapping, and use a digital signal processor (DSP) to extract the sensing information. In our experiment, two cascaded FSLs with two different free spectrum ranges (FSRs) are employed. Due to the Vernier effect, multiple dips in the envelope of the optical spectrum are introduced. By passing a broadband frequency-chirped optical pulse generated by a frequency-swept laser source to the two cascaded FSLs, the sensing information is encoded in the optical spectrum and it is converted to the time domain due to SS-WTT mapping. By detecting the optical waveform at a photodetector (PD), a temporal microwave waveform with its shape identical to the optical spectrum is generated. By using a DSP, the time shift of a dip is measured and the sensing information is precisely demodulated. Experimental result shows that the proposed fiber-optic temperature sensor can provide a temperature resolution of 1.33 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−5</sup> °C at a sensing speed of 23.497 kHz.

Rapid screening of glycoalkaloids in Solanum scabrum and S. nigrum berries using ultra-high-performance liquid chromatography with pathway-specified in-source fragmentation tandem mass spectrometry.

The safe consumption of Solanum scabrum and S. nigrum berries (SNBs) depends on a reliable and rapid chemical screen for the testing of the fruit and/or final food and industrial products for the presence and level of toxic glycoalkaloids. Such a rapid and sensitive screen could also be used by those involved in food safety and forensics, industry, research labs and those in agriculture production, breeding and food processing. Significant variation in the content and composition of glycoalkaloids across SNBs has been reported. To facilitate high-throughput targeted analysis, this work overcame the slow scan speed of a traditional triple quadruple mass spectrometry (QqQ) method by development of a pseudo-MS3 method. In-source fragmentation functioned as a pseudo-MS or pseudo-hydrolysis to trim down the structurally diverse and complex glycosides into five types of aglycone ions, which were then analyzed using multiple reaction monitoring (MRM). Characteristic product ions were selected based on the aglycone skeleton and substitution pattern and associated fragmentation pathway. A compact method with only 15 MRM transitions were developed for high-throughput screening of very diverse glycoalkaloids. Glycosides of the same aglycone type were readily identified in the same transition window without the need for mass spectra interpretation. Validated using solamargine, the sole available standard, the accuracy was 99.7-101.3%, the intra- and inter-day precision were, respectively, 2.5-5.0% and 8.0-9.2%, and the lower limit of detection and quantification were, respectively, 3.1 and 10.2 ng/mL (with 1 μL injection volume). The peudo-MS3 method allowed for high-throughput targeted analysis with compact MRM transitions to address a large number of glycoalkaloids with diverse structures. This method could serve to meet the most heavy-duty demand for rapid inspection of glycoalkaloids in SNBs. This method can be adopted and used by those involved in food safety and forensics, in developing food and industrial products and in genetics and breeding.

Probing the Speed Limits of Scanning Electrochemical Microscopy with In situ Colorimetric Imaging

AbstractDue to the complex nature of probe/substrate interactions in scanning electrochemical microscopy (SECM), SECM has been primarily limited to well‐defined probe geometries and slow scan speeds that reduce imaging throughput. Herein, we show that in situ colorimetric visualization of concentration gradients using pH indicator dyes during SECM measurements can be a powerful tool for understanding the coupled influences of probe geometry and scan speed on the dynamics of localized plumes of electroactive species that mediate probe/substrate interactions. Colorimetric images of plumes generated at a band electrode reveal that probe geometry strongly influences linescan signal distortion and hysteresis at scan speeds surpassing the conventional SECM “speed limit”. Combining mechanistic information from in situ colorimetric imaging with transport models, this article reports design principles that have the potential to enable quantitative SECM with novel probe geometries and at imaging rates that are at least an order of magnitude faster than currently employed.

Control of asymmetric track geometry in printed parts of stainless steels, nickel, titanium and aluminum alloys

In powder bed fusion, distorted temperature fields and deposit dimensions, undesirable surface features, and defects have been attributed to asymmetry in track geometry. It is also thought to affect sensing and control. While data on the asymmetry have been widely reported in the literature for many commonly used alloys, the origin of the asymmetry and the role of alloy composition and process variables are not known. Here we examine the role of local differences in heat transfer from the fusion zone as the origin of asymmetry in the track geometry. We use a mechanistic model of heat transfer and experimental data to examine the role of main process variables and alloy composition on the extent of asymmetry and provide easy-to-use process maps. We show that high laser power and slow scanning speed decreases asymmetry. Marangoni, Fourier and Peclet numbers can be used for controlling asymmetry. Among the four alloys examined, stainless steel 316 and AlSi10Mg are the most and least susceptible to asymmetry because of their lowest and highest thermal diffusivity, respectively.

Direct Fabrication of Ultra-Sensitive Humidity Sensor Based on Hair-Like Laser-Induced Graphene Patterns.

Three-dimensional (3-D) porous graphitic structures have great potential for sensing applications due to their conductive carbon networks and large surface area. In this work, we present a method for facile fabrication of hair-like laser induced graphene (LIG) patterns using a laser scribing system equipped with a 355 nm pulsed laser. The polyimide (PI) film was positioned on a defocused plane and irradiated at a slow scanning speed using a misaligned laser beam. These patterns have the advantages of a large surface area and abundant oxidation groups. We have applied the hair-like LIG patterns to a humidity sensor. The humidity sensor showed good sensitivity characteristics and a large amount of electronic carriers can be stored.

Top-hat and Gaussian laser beam smoothing of ground fused silica surface

Laser smoothing is a promising technique for processing optical glass due non-contact characteristics and easy-adaptability to non-spherical surfaces. The smoothing effects of CO2 laser of top-hat and Gaussian intensity on ground fused silica surfaces were examined in the work. The results show that ground surface with surface micro-roughness of 500 nm (RMS) can be smoothed to <0.5 nm (RMS) with both intensity profiles. Best surface roughness rises with increasing power density of laser and therefore lower power density combined with slow scanning speed is favored to improve surface quality. Numerical model was established to investigate thermal and hydrodynamic transient process to elucidate the underlying mechanism. Simulations show that smoothing process takes place at the same time as the temperature rises due to ever-decreasing viscosity of fused silica. Beam shaping is able to reduce peak power density of high power processing laser and smoothing efficiency might be increased without the loss of the processed quality of glass.

Surface and subsurface characteristics of laser polished Ti6Al4V titanium alloy

This paper aims at investigating the effects of laser power, laser pulse repetition rate and scan speed on the polished metal surface and subsurface characteristics. The influence of initial surface roughness of workpiece on the polishing performance was also taken into account. In this study, Ti6Al4V titanium alloy was selected as a specimen to be polished by a nanosecond pulse laser. The results revealed that the surface roughness was able to be improved by about 43% when the laser fluence of 1–3 J/cm2 was applied. In addition, the proper polishing condition was dependent on the initial surface roughness of workpiece, and a better surface improvement was subjected to a lower initial surface roughness. A thick recast layer, high degree of oxidation and large heat-affected zone with lots of micro-cracks were obtained when too high laser power and slow scan speed were used in the polishing of titanium alloy. With regard to the findings of this study, the suggested polishing conditions could be applied for smoothing the different levels of initial surface roughness of titanium alloy and possibly other similar metals with less subsurface damage.

Conduction modeling of multi-track raster scanning of heat over a rectangular surface region

An analytical conduction model is implemented for the multi-track raster scanning of a heat spot over sequential neighboring tracks upon a half-space surface, focusing on maximum temperature rise as a function of subsurface position as its primary example of a thermal response of interest, with simple rectangular surface regions scanned and the non-dimensionalization of the analysis (to heat spot size and power as well as half-space thermal properties) intended to broaden applicability of model output. As baseline, first the case of isolated single passes is studied, as would also approximate cases of long times between sequential passes, with no heating from a prior pass available to affect that during a following pass. Asymptotic behavior is found describing all slow scanning speed conditions as described by low Peclet number Pe ≤ 0.1, where isotherms of maximum temperature rise may be plotted as a function of position through the subsurface cross-section. Similar description for fast-scanning high Peclet conditions Pe ≥ 40 is also achieved, although temperature rise and depth must both additionally be multiplied by Pe before attaining isotherms asymptotically pertinent for all high Pe. Such high Pe cases are those for which the effect of shorter finite times between neighboring passes is further studied here, since for any given practical stroke length the correspondingly higher scanning speed results in reduced time between passes and thus more opportunity for a heat accumulation effect. Indeed, at a fixed Pe, for a given point within the body cross-section located in proximity to a track several passes into the region being scanned, its temperature rise is greater than for a single isolated pass, and that temperature rise increases further with decreasing time between neighboring passes, as would result from a decreased period of the cyclic scanning motion. This heat accumulation effect builds for passes further into the rectangular surface region from the first track scanned at the region’s edge, and stabilizes after some number of tracks in, a number found to decrease with increased track spacing. Likewise, if instead holding scanning period and in turn time between passes constant, maximum temperature rises at any given position are also found to increase with decreasing Pe, when maximum temperature rise and depth position are expressed in their modified high Peclet asymptotic forms as multiplied by Pe. The analysis further suggests that if maximum temperature rises and depths are both expressed in such modified forms, any further effect of Peclet number may instead be combined with that of non-dimensionalized scanning period as a function only of their product L* = Peτ*, the non-dimensional track length. Finally, while maximum temperature rise behavior around the mid-stroke location will be similar regardless of whether scanning is via back&forth or one-way pass motions and furthermore in one-way motions these maximum temperature rises will remain fairly uniform with position along the track length as each possesses the same elapsed time since proximity during the previous adjacent pass, in back&forth motion the time since proximity during the previous pass before turn-around and in turn maximum temperature rise will instead vary with position along the track.

LiTFSI Concentration Optimization in TEGDME Solvent for Lithium-Oxygen Batteries.

Focus on lithium–oxygen batteries is growing due to their various advantages, such as their high theoretical energy densities and renewable and environmentally friendly characteristics. Nonaqueous organic electrolytes play a key role in lithium–oxygen batteries, allowing the conduction of lithium ions and oxygen transfer in the three phase boundaries (cathode–gas–electrolyte). Herein, we report the effect of lithium salt concentrations in single-solvent lithium–oxygen battery systems systematically (using bis(trifluoromethanesulfonyl)imide (LiTFSI) in tetraethylene glycol dimethyl ether (TEGDME)) on their electrochemical performances. The first discharge capacities and cyclabilities exhibit favorable correlations with the lithium salt concentration, of which using 0.4 and 1.5 M LiTFSI show the best discharge capacities and cyclabilities. The specific capacity of the 0.4 M LiTFSI system reaches 7000 mAh g–1, about 1.3 times that of the commonly used 1 M LiTFSI in TEGDME. Cyclic voltammetry with slow scan speeds further investigates the system stability and reaction mechanism. The surface morphology after the discharge and interface impedance after charging, which are examined using scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS), have significant effects on the comprehensive performances. Conductivity and viscosity play mutual roles in the lithium–oxygen battery performance, while the oxygen solvation has little effect.

Data-Driven Tool Uses Amplitude-Based Statistics To Identify Seismic Fractures

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 191668, “Big Data Analytics for Seismic Fracture Identification Using Amplitude-Based Statistics,” by Egbadon Udegbe, SPE, Eugene Morgan, SPE, and Sanjay Srinivasan, SPE, Pennsylvania State University, prepared for the 2018 SPE Annual Technical Conference and Exhibition, Dallas, 24–26 September. The paper has not been peer reviewed. Data-analysis tools for extracting information about critical subsurface features such as fractures are still evolving. Traditional methods rely on time-consuming iterative work flows, which involve computing seismic attributes, denoising, and expert interpretation. Additionally, the increasingly widespread acquisition of time-lapse seismic surveys has led to heightened demand for reliable automated work flows to assist in deriving feature interpretation from seismic data. The authors present a novel data-driven tool for fast fracture identification in post-stack seismic data•sets. Introduction The paper develops an automated work flow for fast and robust fracture identification that directly uses seismic amplitude data as input. Adapted from real-time face-detection methods, the proposed algorithm computes spatiotemporal amplitude statistics using Haar-like bases to characterize the seismic amplitude properties that correspond to fracture occurrence in a unit window. In this approach, the amplitude data are decomposed into a lower-dimensional collection of simple-to-calculate mini-attributes, which contain gradient and curvature characteristics at varying locations and scales. These features serve as inputs to a cascade of boosted classification trees, which select and combine the most-discriminative features to develop a probabilistic binary classification model. This approach helps to eliminate the computationally intensive and subjective use of seismic attributes in existing approaches. Approach The proposed methodology uses a supervised learning approach. This involves specifying examples of seismic amplitude regions that either contain or do not contain fractures and subsequently presenting these examples to a binary classification scheme that develops a set of rules to distinguish between both fracture and nonfracture windows. Finally, using this trained classification model, any arbitrary amplitude section or volume can be scanned to determine the location of fractures on the basis of the rules defined within the specified window. Training-Window Selection. Careful consideration is required in defining the dimensions of the unit window. In 2D, this unit window is a rectangular region parallel to time and space axes. In 3D, the unit window refers to a cuboidal region with one time and two space axes. The dimensions of the window in the vertical (time) direction are influenced by the time-sampling interval and the source wavelet frequency. In the lateral directions, window dimensions are influenced by the spatial sampling interval, which is a result of the survey acquisition geometry. Overall, smaller unit windows lead to higher resolution in identifying fracture presence. This, however, is achieved at the expense of fewer amplitude features to characterize the window, as well as slower scan speeds, because more regions must be visited to make predictions. Once a seismic amplitude data set with known fracture locations and a unit window with specified dimensions has been established, multiple locations within the data set may be visited and amplitude samples extracted from both fractured and nonfractured regions.

Large-area high-speed scanning probe microscopy using legacy scanners.

In scanning probe microscopy, the scanner dynamically positions the sample relative to the probe, and the upper limit of the imaging speed is governed primarily by the first eigenfrequency of the scanner. The mechanical oscillations of the scanner-even when it operates far from resonance-give rise to image artifacts and negatively affect the image resolution. This paper analytically and experimentally investigates the scanner's dynamics at high scan rates upon scanning over a large area. At slow scan speeds, the frequency spectra of the microcantilever's deflection signal exhibit only the excitation frequency and its harmonics; in contrast, at high scan speeds, the spectra exhibit sidebands centered around the excitation harmonics and separated from them by the scanner's eigenfrequency. Exploiting this phenomenon, a scanner dynamics-based method is proposed to reconstruct the surface topography, and, thereby, to reduce the oscillation-induced image artifacts. The method is proven for a variety of sample surfaces at very high scan rates up to 59.2 Hz (corresponding to a linear speed of 4.74 mm/s) upon scanning over a 40 μm × 40 μm area and is successfully demonstrated to be able to virtually eliminate any image artifacts. A nearly ten-fold increase in the scan rate is demonstrated using even a legacy scanner, with no changes required to the hardware.

Design and implementation of CCD image-based DNA chip scanner with automatic focus calibration

To address the slow scanning speed of the laser confocal method for scanning DNA chips, we designed and built a CCD image-based DNA chip scanner. A high-powered LED was selected as excitation light source. To avoid stray light in the optical path, we designed a light entrance, an extinction dark room, a diaphragm, and an extinctor that eliminated 99.95% of the stray light. A focal automatic calibration scheme is proposed; the only addition to the hardware was the focusing motor and the connection device between the motor and the lens. Furthermore, variance was used as the image sharpness evaluation function, with the combination of rough and fine calibration to increase real-time performance. An experiment showed that the accuracy of automatic focal calibration is higher than that of the manual method with repeatability error of 2.1%, and the time required is between 18.72 and 55.78 s. The sensitivity can reach 1.12 flour/µm2 with a resolution of 10.04 µm. Using the proposed scanner and a commercial Boao scanner on a fluorescence dot on the same genetic defect chip found a consistency coefficient of 0.95. The scanner has the advantage of simple hardware structure, quick detection, and favourite performance.

Laser sintering of cold-pressed Cu powder without binder use

In this work, laser sintering (LS) of cold-pressed copper (Cu) powder without using a binder was demonstrated. To promote the densification of the final part, the Cu powder was cold pressed beforehand, thereby forming a densely packed powder bed for the LS. The densification and microstructural evolution study show that the cold-pressed powder led to an increase of up to 11% in the relative density and a decrease of 10 times in the surface roughness. The influence of the scan speed on the densification and sintering quality was studied. A relatively slow scan speed, 25 µm/s, allowed sufficient atomic diffusion during the LS process and ultimately produced dense Cu parts without cracks and open pores. The introduction of the cold-pressing step into the LS process is critical for achieving high-density powder metallurgy parts without using binders.

A Cross-Hierarchical Scanning Method Based SP-4-WFRFT for Digital Communication Signals

The fractional Fourier transform (FRFT) method has emerged in response to the demand for high-performance time-frequency processing technology. Next, the weighted fractional Fourier transform (WFRFT) method was developed, especially the single-parameter 4-weighted fractional Fourier transform (SP-4-WFRFT), which is most suitable for applications in digital communication systems. Therefore, in receiving systems, research on the scanning method of transformation order has also become the focus of research under the condition of unknown transformation order. However, in the process of inverse transformation, there are many problems, such as long scanning times and slow scanning speed. Thus, to improve the characteristics of a digital communication system based on SP-4-WFRFT, a cross-hierarchical scanning (CHS) method is established. A large number of test results show that the CHS method can achieve fast recovery of data and estimation of transformation order.

Design of a XYZ scanner for home-made high-speed atomic force microscopy

Atomic force microscopy (AFM) is a useful tool in nanoscale measurement. However, conventional AFM suffers from slow scan speed, limiting the use for biological detection or nanofabrication, due to the limited bandwidth of AFM components. In which the resonant frequency of the AFM scanner is usually too low to achieve high-speed scanning. In this paper, a simple and compact home-made high-speed AFM is set up and reported. As an important part of the scanning system, a parallel kinematic piezoelectric actuator (PZT) XYZ scanner is proposed, which can achieve high bandwidth and low coupling errors. Finite element analysis (FEA) is adopted to characterize the scanner, and verified the first two lateral resonance frequency of 5.6 kHz and the vertical resonance frequency is 29 kHz. In addition, some testing experiments are implemented, demonstrating feasibility of the proposed scanner. Finally, it was applied to the home-made AFM system, and some effective scanning imaging results can be obtained.

Three-dimensional nanoscale imaging by plasmonic Brownian microscopy

AbstractThree-dimensional (3D) imaging at the nanoscale is a key to understanding of nanomaterials and complex systems. While scanning probe microscopy (SPM) has been the workhorse of nanoscale metrology, its slow scanning speed by a single probe tip can limit the application of SPM to wide-field imaging of 3D complex nanostructures. Both electron microscopy and optical tomography allow 3D imaging, but are limited to the use in vacuum environment due to electron scattering and to optical resolution in micron scales, respectively. Here we demonstrate plasmonic Brownian microscopy (PBM) as a way to improve the imaging speed of SPM. Unlike photonic force microscopy where a single trapped particle is used for a serial scanning, PBM utilizes a massive number of plasmonic nanoparticles (NPs) under Brownian diffusion in solution to scan in parallel around the unlabeled sample object. The motion of NPs under an evanescent field is three-dimensionally localized to reconstruct the super-resolution topology of 3D dielectric objects. Our method allows high throughput imaging of complex 3D structures over a large field of view, even with internal structures such as cavities that cannot be accessed by conventional mechanical tips in SPM.

Confocal Surface Plasmon Embedded Interferometric Microscope: A Brief Review

In this paper, we firstly explain the concept of surface plasmon resonance imaging and a main key issue in the field of localized SPR imaging, which is the trade-off between resolution and sensitivity. We will then explain how V(z) scanning confocal microscope can overcome the trade-off and enable us to make a localized detection of multiple analytes in small quantities. This paper provides a brief review on a chronological development of the confocal surface plasmon embedded interferometric microscope and highlights the key idea behind each developments. Theoretical detection limit of the confocal system is within a single molecule detection regime, where 100kD molecule can be detected with 100μJ of light in the confocal system. We also discuss some key challenges in achieving the theoretical limit, such as, microphonic vibration and slow scanning speed of the system and how to get around these challenges. Lastly, we discuss some possible future developments to improve the system.

Effect of oxygen annealing on dielectric properties of (In+Nb) doped TiO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; ceramics

Colossal dielectric constant materials have been attracting great attention for their applications in myriad types of miniaturized devices and high-energy-density storage fields. With the demand of size miniaturization in many microelectronic devices, colossal dielectric constant oxides have become essential for modern microelectronic devices, such as dynamic random access memory (DRAM) devices and on-chip capacitors. Recently, in order to obtain the high dielectric permittivity, but with acceptable dielectric loss and less frequency/temperature dependence, the introduction of localized lattice defect states is proposed. Using Nb5+ as electron-donors and In3+ as electron-acceptors is doped into rutile TiO2. And the reduction of Ti4+ ions is affected by the electron-acceptors in the local lattice defect clusters. Thus, the extraordinary colossal permittivity with low dielectric loss over a wide range of frequency and temperature is attributed to the electron-pinned defect-dipoles. There may be complex effects on the origin of novel colossal permittivity properties. In this work, (In1/2Nb1/2)TiO2 ceramics are prepared by the solid state reaction method, and the dielectric properties are studied. Starting materials (TiO2, In2O3, and Nb2O5 99.99%) are weighed as the composition (In1/2Nb1/2)0.05Ti0.95O2. The weighed batches are mixed, calcined, and pressed into disks. Finally, the samples are sintered at 1673 K for 10 h in air, and then some samples are annealed at 1273 K for 5 h in O2 atmosphere (purity 99.99%). The density of the sintered ceramics is initially measured using the geometrical method and then the Archimedes method. The microstructure of the sintered ceramics is investigated with a field electron gun scanning electron microscope (FEI Nova Nano-SEM 450). X-ray diffraction is performed on a Rigaku D/max 2250 diffractometer (Japan) with Cu Kα radiation (40 kV and 50 mA). The data for all the samples are measured with a slow scanning speed 0.01°/s. The crystalline structures are confirmed by using a T64000 Raman spectrometer (Horiba JobinYvon S.A.S., France) with an Ar laser (514.5 nm) operated at 50 mW. The closed cycle cryonic workstation (CFM-9T-H3-IVTI-25 Cryogenic Ltd, London) can provide the temperature range (10–270 K), and dielectric properties are measured at the different frequencies (20 Hz–1 MHz) through an Agilent 4980a LCR meter. The effect of the oxygen annealing on the microstructure, crystal structures and dielectric properties of (In+Nb) co-doped TiO2 ceramics is investigated. The results show that the crystal structure and microstructure are not changed with annealing processing. The annealing process has great effect on the dielectric properties above temperature 60 K. The activation energy changes prove that there possesses at least three different relaxation polarization mechanisms. Both hopping polarization and interfacial polarization are becoming inactive at low temperatures due to insufficient energy to overcome energy barrier for polarization. Complexes polarization associated with InTi′, NbTi·, TiTi′, VO¨ as well as InTi′-NbTi·, InTi′-VO¨-InTi′, InTi′-VO¨-TiTi′, NbTi·-TiTi′, TiTi′-VO¨-TiTi′ are still active as a polarization mechanism. Except for the gathering of the complexes polarization, the interfacial polarization at insulating grain boundary, and polaron polarization due to hopping electron is as co-existing polarization mechanisms in the (In1/2Nb1/2)TiO2 ceramics. The present work identifies the correlation between the colossal permittivity and polaron hopping process in the titled compound.