Significant Enhancement of Piezoelectric Response in AlN by Yb Addition

This study employs first-principles calculations to investigate how introducing Yb into aluminum nitride (AlN) leads to a large enhancement in the material’s piezoelectric response (d33). The maximum d33 is calculated to be over 100 pC/N, which is 20 times higher than that of AlN. One reason for such a significant improvement in d33 is the elastic-softening effect, which is indicated by a decrease in the elastic constant, C33. The strain sensitivity (du/dε) of the internal parameter, u, is also an important factor for improving the piezoelectric stress constant, e33. On the basis of mixing enthalpy calculations, YbxAl1−xN is predicted to be more stable as a wurtzite phase than as a rock salt phase at composition up to x ≈ 0.7. These results suggest that Yb can be doped into AlN at high concentrations. It was also observed that the dielectric constant, ε33, generally increases with increasing Yb concentrations. However, the electromechanical coupling coefficient, k332, only increases up to x = 0.778, which is likely because of the relatively lower values of ε33 within this range.

Download Full-text

A novel magnetic ZnFe2O4 aerogel photocatalyst for visible light reduction of Cr(VI) at high concentrations: Facile synthesis, enhanced activity and photocatalytic mechanism, combined with first-principles calculations

Ceramics International ◽

10.1016/j.ceramint.2021.10.184 ◽

2021 ◽

Author(s):

Shun-tian Huang ◽

Ju-xiang Tai ◽

Wen-ke Hao ◽

Jia-xin Lu ◽

Si-jia Liu ◽

...

Keyword(s):

Visible Light ◽

First Principles ◽

First Principles Calculations ◽

Facile Synthesis ◽

Light Reduction ◽

Photocatalytic Mechanism ◽

Enhanced Activity ◽

High Concentrations

Download Full-text

DEPENDENCE OF PHYSICAL PROPERTIES OF PIEZOELECTRIC ALUMINUM-SCANDIUM NITRIDE ON SCANDIUM CONCENTRATION

IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA ◽

10.6060/ivkkt.20216406.6384 ◽

2021 ◽

Vol 64 (6) ◽

pp. 95-103

Author(s):

Vladlen V. Zhukov ◽

Denis A. Shcherbakov ◽

Pavel B. Sorokin ◽

Boris P. Sorokin

Keyword(s):

Physical Properties ◽

Rock Salt ◽

Density Functional ◽

Piezoelectric Constant ◽

Bulk Acoustic Wave ◽

Piezoelectric Response ◽

Wurtzite Phase ◽

Scandium Nitride ◽

Salt Phase ◽

Frequency Dependences

In this work the physical properties of the piezoelectric aluminum-scandium nitride (ASN) solid solution as a function of scandium concentration were studied using the density functional theory and experimental methods. The phase transition from the wurtzite phase to the rock salt phase at a Sc concentration of 43% was shown. The barriers of transformation from the wurtzite phase to the rock salt phase for various Sc concentrations were obtained. The behavior of the ASN piezoelectric constant d33 calculated by the piezoelectric constants e33, e31, and e15 shows a sharp increase with increasing Sc concentration compared to aluminum nitride AlN. The relationship between the increase in the piezoelectric response of ASN and the softening of the lattice, accompanied by a decrease in the main elastic constants C11, C33, C44 and C66, as well as a decrease in the c/a ratio with increasing Sc concentration, is shown. ASN films with a predominance of the crystal orientation (00·2) were obtained experimentally by magnetron sputtering. The structural properties of the films were studied by X-ray diffraction analysis. A comparison of the experimentally obtained dependence of the c/a ratio on the Sc concentration with the theoretical values showed a good correspondence. Studies of the physical properties of ASN thin films were performed using microwave multi-overtone composite resonators on diamond substrates with a longitudinal bulk acoustic wave (BAW) as the operating mode in the range of 0.5 – 20 GHz. The frequency dependences of the Q-factor of BAW-resonators with different ASN films were obtained, and the frequency dependences of the square of the modulus of the form factor as |m|2 were calculated. The dependences of the elastic constant С33 and the piezoelectric constant e33 for the ASN films with different Sc concentrations were calculated. The calculated and measured values of these constants are agreed within the experimental error.

Download Full-text

Effect of Additive Glycerol on Piezoelectric Properties of Modified Sol-Gel (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 Ceramics

Materials Science Forum ◽

10.4028/www.scientific.net/msf.993.791 ◽

2020 ◽

Vol 993 ◽

pp. 791-798

Author(s):

Haibibu Aziguli ◽

Tao Zhang ◽

Ping Yu

Keyword(s):

Grain Size ◽

Electromechanical Coupling ◽

Piezoelectric Coefficient ◽

Piezoelectric Properties ◽

Environmental Concern ◽

Sol Gel ◽

Lead Free ◽

Piezoelectric Response ◽

Electromechanical Coupling Coefficient ◽

Ceramic Powders

Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCTZ) ceramics, one of the lead-free pizoelectric materials, were focused due to the environmental concern against lead. A modified BCTZ powder sol-gel fabrication process was experimentally introduced with the addition of glycerol, in order to provide an effective approach to optimize the piezoelectric response of BCTZ ceramics. The results showed that the piezoelectric properties enhanced in terms of the piezoelectric coefficient of d33, 510 pC/N and the electromechanical coupling coefficient of kp, 0.501. The enhancement in electrical properties, such as dielectric, ferroelectric and piezoelectric, could be related to the homogenous microstructure and larger grain size of BCTZ ceramic powders after the introduction of glycerol during the modified sol-gel strategy.

Download Full-text

Large piezoelectric response in a family of metal-free perovskite ferroelectric compounds from first-principles calculations

npj Computational Materials ◽

10.1038/s41524-019-0157-4 ◽

2019 ◽

Vol 5 (1) ◽

Cited By ~ 9

Author(s):

Hui Wang ◽

Huihui Liu ◽

Zeyu Zhang ◽

Zihan Liu ◽

Zhenlong Lv ◽

...

Keyword(s):

First Principles ◽

Piezoelectric Response ◽

First Principles Calculations ◽

Metal Free

Download Full-text

Effect of Low-Temperature Frit on the Sintering Behavior and Properties of 0.95K0.49Na0.51NbO3-0.05LiSbO3 Lead-Free Piezoceramics

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.412.290 ◽

2011 ◽

Vol 412 ◽

pp. 290-293

Author(s):

Zhu Mei Wang ◽

Yue Ming Li ◽

Run Run Li ◽

Zong Yang Shen ◽

Yan Hong

Keyword(s):

Low Temperature ◽

Electromechanical Coupling ◽

Sintering Temperature ◽

Mechanical Quality Factor ◽

Lead Free ◽

Piezoelectric Response ◽

Electromechanical Coupling Coefficient ◽

Sintering Behavior ◽

Mechanical Quality ◽

Reduced Temperature

The effects of low-temperature frit Li2O-Na2O-K2O-B2O3-SiO2-CaO-BaO-ZnO (abbreviated as BS) on the sintering behavior and electrical properties of 0.95K0.49Na0.51NbO3- 0.05LiSbO3 (abbreviated as KNN-LS) lead-free piezoceramics were investigated. The sintering temperature of the KNN-LS ceramics can be reduced from 1080 °C to 1000 °C due to the addition of BS frit. For the 0.5 wt% BS-doped KNN-LS ceramics, which are sintered at reduced temperature of 1000 °C for 2 h, remain relatively high piezoelectric constant d33 (195 pC/N) and planar electromechanical coupling coefficient kp (40.7%). In addition to other optimization effects, such as reduction of dielectric loss from 3.6% to 2.7% and increment of mechanical quality factor Qm from 48 to 70, this BS frit was experimentally proved to be good for low temperature sintering of KNN-based ceramics while maintaining high piezoelectric response.

Download Full-text

Piezoelectricity in hafnia

Nature Communications ◽

10.1038/s41467-021-27480-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Sangita Dutta ◽

Pratyush Buragohain ◽

Sebastjan Glinsek ◽

Claudia Richter ◽

Hugo Aramberri ◽

...

Keyword(s):

First Principles ◽

Piezoelectric Effect ◽

Piezoresponse Force Microscopy ◽

Perovskite Oxides ◽

Ferroelectric Material ◽

Active Oxygen ◽

Piezoelectric Response ◽

First Principles Calculations ◽

Force Microscopy ◽

Epitaxial Strain

AbstractBecause of its compatibility with semiconductor-based technologies, hafnia (HfO2) is today’s most promising ferroelectric material for applications in electronics. Yet, knowledge on the ferroic and electromechanical response properties of this all-important compound is still lacking. Interestingly, HfO2 has recently been predicted to display a negative longitudinal piezoelectric effect, which sets it apart from classic ferroelectrics (e.g., perovskite oxides like PbTiO3) and is reminiscent of the behavior of some organic compounds. The present work corroborates this behavior, by first-principles calculations and an experimental investigation of HfO2 thin films using piezoresponse force microscopy. Further, the simulations show how the chemical coordination of the active oxygen atoms is responsible for the negative longitudinal piezoelectric effect. Building on these insights, it is predicted that, by controlling the environment of such active oxygens (e.g., by means of an epitaxial strain), it is possible to change the sign of the piezoelectric response of the material.

Download Full-text

Thermodynamic Stability, Thermoelectric, Elastic and Electronic Structure Properties of ScMN2-Type (M = V, Nb, Ta) Phases Studied by ab initio Calculations

Condensed Matter ◽

10.3390/condmat4020036 ◽

2019 ◽

Vol 4 (2) ◽

pp. 36 ◽

Cited By ~ 1

Author(s):

Robert Pilemalm ◽

Leonid Pourovskii ◽

Igor Mosyagin ◽

Sergei Simak ◽

Per Eklund

Keyword(s):

Thermoelectric Properties ◽

Thermodynamic Stability ◽

First Principles ◽

Density Functional ◽

Mixing Enthalpy ◽

First Principles Calculations ◽

Electronic Density ◽

Functional Theory ◽

Small Band ◽

Structure Properties

ScMN2-type (M = V, Nb, Ta) phases are layered materials that have been experimentally reported for M = Ta and Nb, but they have up to now not been much studied. However, based on the properties of binary ScN and its alloys, it is reasonable to expect these phases to be of relevance in a range of applications, including thermoelectrics. Here, we have used first-principles calculations to study their thermodynamic stability, elastic, thermoelectric and electronic properties. We have used density functional theory to calculate lattice parameters, the mixing enthalpy of formation and electronic density of states as well as the thermoelectric properties and elastic constants (cij), bulk (B), shear (G) and Young’s (E) modulus, which were compared with available experimental data. Our results indicate that the considered systems are thermodynamically and elastically stable and that all are semiconductors with small band gaps. All three materials display anisotropic thermoelectric properties and indicate the possibility to tune these properties by doping. In particular, ScVN2, featuring the largest band gap exhibits a particularly large and strongly doping-sensitive Seebeck coefficient.

Download Full-text

Thermodynamic description of Ge-Mn-Si

MRS Proceedings ◽

10.1557/opl.2014.448 ◽

2014 ◽

Vol 1642 ◽

Author(s):

Alexandre Berche ◽

Jean-Claude Tédenac ◽

Philippe Jund ◽

Stéphane Gorsse

Keyword(s):

Solid Solution ◽

Gibbs Energy ◽

First Principles ◽

Thermodynamic Description ◽

Intermetallic Phases ◽

Calphad Method ◽

Enthalpies Of Formation ◽

Mixing Enthalpy ◽

First Principles Calculations ◽

First Time

ABSTRACTLiterature data of the Mn-Si system is analyzed and discordances are pointed out. First principles calculations are performed to clarify the enthalpies of formation of the intermetallic phases. Especially the enthalpies of formation of the various possible structures of the MnSix are discussed. On the basis of these new data, a thermodynamic description of the Gibbs energy of the phases is performed using the Calphad method. The system Ge-Mn is also assessed using the Calphad method for the first time.The mixing enthalpy in the D88 solid solution is calculated between Mn5Ge3 and Mn5Si3 by DFT calculations.Finally a thermodynamic description of the ternary system is suggested. Especially the solubility of germanium in MnSix is modeled.

Download Full-text

Atomic Dynamics During Silicon Oxidation and the Nature of Defects at the Si-SiO2 Interface

MRS Proceedings ◽

10.1557/proc-490-59 ◽

1997 ◽

Vol 490 ◽

Cited By ~ 4

Author(s):

S. T. Pantelides ◽

M. Ramamoorthy

Keyword(s):

Thin Film ◽

First Principles ◽

Atomic Scale ◽

Theoretical Research ◽

First Principles Calculations ◽

Common Features ◽

Oxygen Precipitation ◽

High Concentrations ◽

Unified Description

ABSTRACTOxidation of thin-film Si, oxygen precipitation in bulk crystalline Si, and the formation of buried oxide layers (as in the SIMOX process for SOI) have been studied extensively for decades but the underlying atomic scale processes have remained elusive. Furthermore, common features of these phenomena have not been generally appreciated, in part because the kinetics are substantially different in the different cases. In this paper we review recent theoretical research based on atomic-scale first-principles calculations that provides a unified description of the three phenomena. In particular, we account for both the normal and enhanced mode of oxygen diffusion that leads to the formation of oxygen clusters known as thermal donors and their subsequent annealing and evolution into SiO2-like precipitates. It is proposed that a novel family of interface defects that are akin to thermal donors, composed of “frustrated” Si-O bonds, are a natural by-product of thin-film oxidation. An explicit mechanism for the emission of Si interstitials, which occurs during both oxidation and oxygen precipitation, is obtained. It is shown that emission of Si interstitials eliminates the frustrated-bond defects, thus explaining the high quality of the resulting interfaces. It is proposed that frustrated-bond defects are responsible for much of the behavior observed at the Si-SiO2 interface that cannot be accounted by dangling bonds and for the amphoteric traps that occur in high concentrations in SOI material.

Download Full-text