Influence of isovalent Cd doping concentration and temperature on electric and dielectric properties of ZnO films

Altun, Büşra; Ajjaq, Ahmad; Çağırtekin, Ali Orkun; Er, İrmak Karaduman; Sarf, Fatma; Acar, Selim

doi:10.1016/j.ceramint.2021.06.147

Cited by 22 publications

(7 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The impedance imaginary part values first ascended with the increase in frequency, approached the maximum value, and then descended for all the samples at various temperatures. These observations show that more than one relaxation phenomena are present in our models [66,67].…”

Section: Morphological Analysissupporting

confidence: 57%

Structural, impedance, dielectric and optical characteristics of Cd- substituted Zn_(1−x)Cd_xO nanoparticles at low temperatures

Ahmad¹,

Maqsood²

2021

Phys. Scr.

View full text Add to dashboard Cite

Nanocrystalline Cd substituted ZnO nanoparticles with common formula Zn (1-x) CdxO (x = 0%, 3%, 6%, and 10%) were fabricated by a co-precipitation technique. X-ray diffraction (XRD) and scanning electron microscopy (SEM) was used to investigate the microstructures and morphology of synthesized nanoparticles at room temperature. The outcome of the x-ray diffraction (XRD) study supports the existence of wurtzite crystal structure for ZnO, and Cd substituted ZnO samples conformed that substituted Cd ions are catching up Zn site. The morphological assessments of the fabricated nanoparticles indicated that the nature of the nanoparticles is a slightly hexagonal and mostly spherical shape with size ranges 46-55 nm. The electric impedance of the samples was measured in a wide range of frequency 100Hz–2MHz at different temperatures (140 K-260 K) using an LCR meter. It was observed that the dielectric constants (ἐ), (ε´´), loss tangent (tanδ), and ac conductivity of pure and Cd substituted ZnO nanoparticles depended on frequency. The calculations of dielectric measurement showed that the parameters (ἐ), (ε´´), loss tangent (tanδ) decreased with the increase in frequency. But the ac conductivity enhanced with the frequency, whereas the values of the above parameters increased with the temperature rise. The dielectric parameters are also found to improve with the increase in Cd concentrations. The correlated barrier-hopping (CHB) model dominated in ac conductivity. The reduction in the bandgap was also observed with Cd concentration.

show abstract

Section: Morphological Analysissupporting

confidence: 57%

Structural, impedance, dielectric and optical characteristics of Cd- substituted Zn_(1−x)Cd_xO nanoparticles at low temperatures

Ahmad¹,

Maqsood²

2021

Phys. Scr.

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 99%

“…By AC impedance spectroscopy, the impedance of the ZOL3 sensor [expressed as a complex number (Z* = Z′ + jZ″)] was measured in a wide frequency range from 20 Hz to 10 MHz, where the real component Z′ = Z cos θ represents the resistance and the imaginary component Z″ = Z sin θ represents the reactance (capacitance and inductance) of the sensor. 74 In these equations, θ = ωRC is the phase shift where ω is the angular frequency, R is the resistance, and C is the capacitance of the sensor. 75 When ammonia gas is introduced to the sensor, the impedance curve in the Cole−Cole plot shifted upward (i.e., toward higher impedance values) at 30 °C (Figure 4a), while it shifted downward (i.e., toward lower impedance values) at 150 °C (Figure 4b).…”

Section: Acs Sensorsmentioning

confidence: 99%

Advanced NH₃ Detection by 1D Nanostructured La:ZnO Sensors with Novel Intrinsic p–n Shifting and Ultrahigh Baseline Stability

Ajjaq,

Bulut,

Ozturk

et al. 2024

ACS Sens.

Self Cite

View full text Add to dashboard Cite

Due to its stability, transportability, and ability to be produced using renewable energy sources, NH 3 has become an attractive option for hydrogen production and storage. Detecting NH 3 is then essential, being a toxic and flammable gas that can pose dangers if not properly monitored. ZnO chemiresistive sensors have shown great potential in real NH 3 monitoring applications; yet, research and development in this area are ongoing due to reported limitations, like baseline instabilities and sensitivity to environmental factors, including temperature, humidity, and interferent gases. Herein, we suggest an approach to obtain sensors with competitive performance based on ZnO semiconducting metal oxides. For this purpose, one-dimensional nanostructured pure and La-doped ZnO films were synthesized hydrothermally. Incorporating large rare earth ions, like La, into the bulk lattice of ZnO is challenging and can lead to surface defects that are influential in gassensing reactions. The sensors experienced a temperature-induced p−n shifting at about 100 °C, verified by the Hall effect and AC impedance measurements. The doped sensor showed exceptional stepwise baseline stability and outstanding performance at a relatively low operating temperature (150 °C) with a sensing response of 91 at best (@ 50 ppm NH 3 ) and recorded a tolerance to water vapor up to 70% RH. Alongside p−n shifting, the enhanced performance was discussed in correlation with La doping-triggered changes in the nanostructural and surfacial properties of the films. We validated the proposed technique by producing similar sensors and performing multiple replicates to ensure consistency and reproducibility. We also introduced the fill factor concept into the gas sensor field as a new trustworthy parameter that could improve sensor performance assessment and help rate sensors based on deviation from ideality.

show abstract

“…Thus, the surficial NO sensing features can be understood from the values of activation energies. The rate of resistance change versus temperature for NO target gas can be presumed using the following Arrhenius equation 70 = i k j j j y { z z z R R E kT exp 0 (12) where R is the sensor resistance, K is the Boltzmann factor, T is the temperature (in K), and ΔE is the activation energy. For the estimation of activation energies, the resistance rate change was calculated using the resistance versus time curves on exposure to NO gas with a 100 ppm concentration at different operating temperatures (see Figure S6 in the Supporting Information).…”

Section: Xps Analysismentioning

confidence: 99%

Quick NO Gas Sensing by Ti-Doped Flower–Rod-like ZnO Structures Synthesized by the SILAR Method

Soltabayev

Yergaliuly

Ajjaq

et al. 2022

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

In this study, Ti-doped ZnO films with flower−rod-like nanostructures were synthesized by the successive ionic layer adsorption and reaction (SILAR) method for enhanced NO gas-sensing applications. The stoichiometric ratio of Ti in the host ZnO lattice was confirmed by atomic absorption and energy-dispersive X-ray spectroscopies. All of the synthesized films exhibited a pure wurtzite hexagonal structure that seemed to deteriorate at high Ti doping contents as was manifested by the measured X-ray diffraction patterns. Scanning electron microscopy images of ZnO revealed the coexistence of porous flower-and rod-like structures, which became finer, denser, and more compact with Ti doping. By UV−vis measurements, the transmittance of the synthesized pure ZnO thin film in the visible region (∼75%) increased by about 10% with Ti doping, and the energy band gap seemed to decrease up to some limit of Ti content. Among the fabricated sensors (based on pure ZnO, 1% Ti-doped, 3% Ti-doped, and 5% Ti-doped ZnO films), the best sensing performance was observed for the 1% Ti-doped ZnO film. At first, this was associated with its high density of oxygen vacancies present on the surface of the film and ionized oxygen vacancies present in the ZnO lattice (confirmed, respectively, by X-ray photoelectron and photoluminescence spectroscopies). Nonetheless, this may also be due to its increased crystallinity (confirmed by X-ray diffraction and photoluminescence spectroscopy), high area-to-volume ratio (confirmed by scanning electron microscopy images), high specific surface area (confirmed by Brunauer−Emmett−Teller measurements) as well as high mobility and carrier concentration (confirmed by Hall measurements). The sensor was highly selective to NO gas and showed notable stability as well as very short response and recovery times, which makes it eligible for the early detection of any indoor or outdoor NO gas leakages.

show abstract

Influence of isovalent Cd doping concentration and temperature on electric and dielectric properties of ZnO films

Cited by 22 publications

References 34 publications

Structural, impedance, dielectric and optical characteristics of Cd- substituted Zn_(1−x)Cd_xO nanoparticles at low temperatures

Structural, impedance, dielectric and optical characteristics of Cd- substituted Zn_(1−x)Cd_xO nanoparticles at low temperatures

Advanced NH₃ Detection by 1D Nanostructured La:ZnO Sensors with Novel Intrinsic p–n Shifting and Ultrahigh Baseline Stability

Quick NO Gas Sensing by Ti-Doped Flower–Rod-like ZnO Structures Synthesized by the SILAR Method

Contact Info

Product

Resources

About

Influence of isovalent Cd doping concentration and temperature on electric and dielectric properties of ZnO films

Cited by 22 publications

References 34 publications

Structural, impedance, dielectric and optical characteristics of Cd- substituted Zn(1−x)CdxO nanoparticles at low temperatures

Structural, impedance, dielectric and optical characteristics of Cd- substituted Zn(1−x)CdxO nanoparticles at low temperatures

Advanced NH3 Detection by 1D Nanostructured La:ZnO Sensors with Novel Intrinsic p–n Shifting and Ultrahigh Baseline Stability

Quick NO Gas Sensing by Ti-Doped Flower–Rod-like ZnO Structures Synthesized by the SILAR Method

Contact Info

Product

Resources

About

Structural, impedance, dielectric and optical characteristics of Cd- substituted Zn_(1−x)Cd_xO nanoparticles at low temperatures

Structural, impedance, dielectric and optical characteristics of Cd- substituted Zn_(1−x)Cd_xO nanoparticles at low temperatures

Advanced NH₃ Detection by 1D Nanostructured La:ZnO Sensors with Novel Intrinsic p–n Shifting and Ultrahigh Baseline Stability