Subjects: Materials Science >> Materials Science (General) submitted time 2023-02-14 Cooperative journals: 《桂林电子科技大学学报》
Abstract： In order to investigate the magnetoelectric coupling performance of BaFe10.2Sc1.8O19 samples at room temperature,
BaFe10.2Sc1.8O19 samples were prepared by solid phase method and sol-gel method. The phase structure was determined by
X-ray diffraction, the prepared samples are all single-phase polycrystals with a space group of P63/mmc. The surface morphology
was observed by field emission scanning electron microscopy, the samples prepared by solid phase method show that
there is not uniform in composition and a "scandium-rich phase". The morphology analysis of the sample prepared by sol-gel
method shows that the grains of BaFe10.2Sc1.8O19 exhibit uniform distribution with hexagonal platelet-shaped structure, and
the grain size is about 3-5 μm. The magnetic results of the samples prepared by the sol-gel method and the solid state reaction
show that the solid state reaction sample undergoes phase transition at about 250 K, and the hysteresis line does not exhibit
magnetoelectric coupling behavior at room temperature; Temperature and magnetic field dependence of magnetization
for the sample prepared by sol-gel method show that BaFe10.2Sc1.8O19 exhibits ferrimagnetic to conical spin structures phase
transition near 330 K. Magnetic field dependence of magnetocapacitance is similar to the behavior in magnetization, which
indicate that the systems exist ferroelectric polarization induced by the conical spin structures. It can be understood by the
inverse Dzyaloshinskii-Moriya model.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-02-14 Cooperative journals: 《桂林电子科技大学学报》
Abstract： In order to improve the performance of BaTiO3 cermics, barium titanate ceramics were prepared by microwave
sintering method, using barium titanate powder synthesized by solid-state method as raw material. The samples were characterized
by XRD, SEM, XPS, LCR analyzer. And the differences between the composition segregation of barium titanate
ceramic particles prepared by microwave sintering and traditional sintering were also analyzed. The results show that the
barium titanate ceramic particles prepared by microwave sintering are uniform in size and the Ba atom at the interface is less
segregation. So the room temperature dielectric constant of barium titanate ceramic is significantly improved. The particle
size of barium titanate ceramics microwave sintered at 1 100 ℃ for 2 h is about 1 μm. And its dielectric constant at room
temperature at 10 kHz is 5 688, and the dielectric loss is 0.021. The section of barium titanate ceramic that has been conventional
sintered at 1 250 ℃ for 2 h does not have obvious particles, which is the dielectric constant at room temperature at
10 kHz is only 3 257, and the dielectric loss is 0.021.
Subjects: Materials Science >> Materials Science (General) submitted time 2022-10-26 Cooperative journals: 《桂林电子科技大学学报》
Abstract： In order to study the electrochemical performance of ternary transition metal oxide as a sodium electrode, hollow
Ni0.75Zn0.25Fe2O4 nanospheres with a diameter of approximately 230 nm were prepared through hydrothermal method. The
prepared hollow Ni0.75Zn0.25Fe2O4 nanospheres have a high specific surface area of 32.6 m2/g and good dispersibility. Hollow
Ni0.75Zn0.25Fe2O4 nanospheres show good cycle life and rate performance when used as the negative electrode of sodium
ion batteries: After 800 cycles at a current density of 200 mA/g, there is still a discharge specific capacity of 178.5 mA·h/g, and
the capacity retention rate is as high as 91.6%; After 800 cycles at a current density of 500 mA/g, the capacity retention
rate is 89.3%. In addition, when the current density is 100, 200, 500, 1 000 and 2 000 mA/g, the average discharge specific
capacity is 212.7, 191.4, 148, 121.8 and 100 mA·h/g, respectively. The good electrochemical performance of the hollow
Ni0.75Zn0.25Fe2O4 nanosphere electrode can be due to its unique hollow structure of the nanosphere, high specific surface
area and shortened electron and ion transmission path, which improve its electrochemical performance during the Na+ insertion/
desorption process.
Subjects: Materials Science >> Materials Science (General) submitted time 2022-10-26 Cooperative journals: 《桂林电子科技大学学报》
Abstract：
In order to study the magnetic phase transition and dielectric relaxation of TbCrO3 at low temperature, TbCrO3
samples were prepared by the sol-gel self-propagating combustion synthesis method, and its magnetic and electrical properties
were analyzed. The crystal structue and physical properties of TbCrO3 were characterized by X-ray diffractometer, field
emission scanning electron microscope and physical property measurement system, respectively. X-ray diffraction results
show that the synthesized TbCrO3 is single with Pbnm space group. The DC magnetization curve shows that the Neel temperature
of the material is TN=162 K, the theoretical value of the effective magnetic moment of the molecule is consistent
with the experimental value obtained by extrapolation of the high-temperature paramagnetic section of the magnetization
curve, indicating that the magnetic properties of the sample follow Curie's law, the Weiss constant is negative (-32.2 K),
indicating the antiferromagnetic coupling characteristics inside the sample. In the dielectric measurement, at low frequency
and high temperature, the sample has dielectric dispersion and giant dielectric constant, which is attributed to space charge
polarization. The sample shows dielectric relaxation near 200 K, and the loss peak moves to high temperature with increasing
frequency. The fitted activation energy is 0.358 eV, which is close to the activation energy of other samples in the
RCrO3 system. According to the relationship between the imaginary part of the dielectric constant and the frequency, the relaxation
is the Maxwell-Wagner relaxation. From impedance spectroscopy analysis, relaxation is caused by the interaction of
grain boundaries and grains. TbCrO3 has a paramagnetic-antiferromagnetic phase transition at low temperature, and dielectric
relaxation shows thermal activation behavior.
Subjects: Materials Science >> Electronic, Optical and Magnetic Materials submitted time 2022-10-26 Cooperative journals: 《桂林电子科技大学学报》
Abstract： In order to improve the magnetic properties of permanent magnetic films and increase the utilization of Ce elements,
the magnetization reversal process of the dual main phase Nd2Fe14B/Ce2Fe14B periodic multilayer film has been
simulated, and the influence of the thickness of the magnetic layer and the number of layers of the multilayer film on the
magnetic properties of the periodic multilayer film during the magnetization reversal process has been systematically studied.
The remanence, coercivity, hysteresis loop of the system and the energy change during the magnetization reversal process
and the magnet are analyzed. The coercive force mechanism will provid a certain reference for the preparation of high-performance
magnets with high Ce content in the future. The research results show that when the thickness of the fixed multilayer
film is constant and the number of the fixed multilayer film is constant, with the increase of the thickness of the magnetic
layer, the coercive force and maximum magnetic energy product of the system gradually decrease; The coercive force
mechanism is mainly dominated by nucleation; when other conditions are the same, the coercivity and magnetic energy product
of the parallel-oriented periodic multilayer film are better than those of the perpendicularly-oriented periodic multilayer
film; the total thickness of the periodic multilayer film increases Will reduce the influence of orientation on coercivity. The
research results will help to deepen understand the magnetization reversal mechanism of the dual-phase Nd-Fe-B/Ce-Fe-B
magnets, and provide a certain reference for optimizing the magnetic properties of permanent magnet films in future experiments.
Key wor
Subjects: Energy Science >> Energy Science （General） submitted time 2022-10-26 Cooperative journals: 《桂林电子科技大学学报》
Abstract： Aerogels with high porosity and low thermal conductivity can absorb sunlight and convert them into thermal energy
to heat water, thus are widely used in the field of solar vapor generation to achieve efficient desalination and sewage treatment.
In order to improve the evaporation rate of aerogels, PAM-PDA-PEG modified aerogels were prepared by freeze-drying
using polyacrylamide (PAM) with good absorbency as substrate, polydopamine (PDA) as hydrophilic modification material
and polyethylene glycol (PEG) as dispersant. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy
(FTIR), ultraviolet/visible/near-infrared spectrophotometer (UV-vis-NIR), water contact angle and Raman spectroscopy
(Raman) were used to characterize the micromorphology, chemical composition, optical properties, hydrophilicity
and water state of the modified aerogels. The photothermal conversion performance of PAM-PDA-PEG were also tested by
simulated evaporation system. The results show that the photothermal conversion performance of pure PAM is weak, but
the modified PAM-PDA-PEG aerogels not only have good absorbance and hydrophilicity, but also contain a large amount of
intermediate water which can effectively reduce the energy required for evaporation. Under the light intensity of 1 kW·m-2,
the evaporation rate of PAM-PDA-PEG reaches 2.40 kg·m-2·h-1, which is five times that of pure PAM. In addition, desalination
and dye removal experiments proved the practical application ability of PAM-PDA-PEG.
Subjects: Materials Science >> Materials Science (General) submitted time 2022-10-26 Cooperative journals: 《桂林电子科技大学学报》
Abstract： Silver selenide (Ag2Se) is a typical thermoelectric material suitable for application near room temperature. Doping
heteroatom is an effective method to optimize the thermoelectric properties. However, the precise doping of Ag2Se prepared
by the wet chemical methods is difficult to accomplish. To achieve precise control of doping content, which is important to
obtain Ag2Se-based materials with high thermoelectric performance, the Ag2Se powders were synthesized by a hydrothermal
method using ethylenediamine as the solvent, silver nitrate (AgNO3) and elemental selenium (Se) as the raw materials.
Then, the matrix Ag2Se was doped with elemental sulfur(S) by a melting method, and bulk materials with high thermoelectric
performance is prepared by a spark plasma sintering (SPS). X-ray diffraction (XRD) and energy dispersive spectrometer
(EDS) were used to conduct phase analysis and microscopic element analysis of the sample doped with sulfur in different
content, and the thermoelectric performance at 300-400 K was tested by a thermoelectric performance test system. The result
shows that the doped sample achieves a significant increase in Seebeck coefficient(α) and a decrease in thermal conductivity(
κ) in the low temperature phase. The Seebeck coefficient (α) of the sample with a doping content of 3% mole is about
-152 μV K- 1 at 393 K, and the thermal conductivity (κ) is 0.91 W m-1 K-1 at 393 K. Finally, the sample doped by 3%
molar sulfur reaches a peak zT to 0.81 at 393 K.
Subjects: Materials Science >> Materials Science (General) submitted time 2022-10-26 Cooperative journals: 《桂林电子科技大学学报》
Abstract： To adopt a low energy consumption and short time-consuming method, high-performance silver selenide (Ag2Se)
based thermoelectric materials was prepared. The different silver-selenium molar ratios (nAgNO3/nSe) silver selenide powder
was synthesized by solvothermal method using ethylenediamine as the solvent, silver nitrate (AgNO3) and elemental selenium
(Se) as raw materials. After spark plasma sintering (SPS) process, the block was obtained. X-ray diffraction (XRD)
and scanning electron microscope (SEM) were used to conduct phase analysis and microscopic morphology observation of the
sample. The thermoelectric performance test system was used to test the pyroelectric performance of the sample. The performance
of the sample was verified by simulation calculation and actual output voltage test of thermoelectric power generation
device. The results shows that with the increase of nAgNO3/nSe, the diffraction peak of the second phase Ag element in
the silver selenide powder increases, which is beneficial to optimize the carrier transport characteristics of the sample. The
highest thermoelectric figure of merit (zT) about 0.74 at room temperature is obtained when the nAgNO3/nSe is 2∶1. A maximum
zT of 1.07 is achieved at 393 K and its average zT value (zTavg) during 303 K~393 K is about 0.82 when the
nAgNO3/nSe is 1.9∶1. Simulation calculation and actual output voltage test of thermoelectric power generation show that the experimentally
prepared silver selenide bulk thermoelectric material is promising to replace N-type Bi2Te3 based thermoelectric material.
Subjects: Materials Science >> Materials Science (General) submitted time 2022-10-26 Cooperative journals: 《桂林电子科技大学学报》
Abstract： In order to study the effect of Sn doping on the structure and thermoelectric properties of ZrCoBi compounds, a series
of ZrCoBi1-xSnx(x=0, 0.05, 0.10, 0.15, 0.20, 0.25) samples with different doping concentrations were prepared by
induction smelting combined with sparking plasma sintering. The phase structure and thermoelectric properties of ZrCo-
Bi1-xSnx samples were tested and analyzed. The experimental results show that the synthesized ZrCoBi based compounds
are all standard Half-Heusler phase, and the maximum solid solubility of Sn in the ZrCoBi matrix is 20%. At the same temperature,
with the increase of Sn doping concentration at the Bi site, the conductivity increases, the Seebeck coefficient increases
first and then decreases, and the ZT value increases continuously. By Sn/Bi substitution, the thermal conductivity of
ZrCoBi1-xSnx is significantly reduced, and the lowest value of the thermal conductivity of ZrCoBi0.80Sn0.20sample is 2.56
W·cm-1·k-1 around 730 K. Due to the increase of power factor and the decrease of thermal conductivity, the ZT value increases
from 0.39 of the undoped ZrCoBi sample to 1.02 of the maximum ZrCoBi0.20Sn0.80 sample around 730 K. Sn doping
introduces acceptor impurity, optimizes carrier concentration, and improves conductivity and power factor. At the same
time, because of the size and mass difference between Sn and Bi atoms, the point defect scattering is enhanced, and the thermal
conductivity is further reduced, thus the ZT value is increased and the thermoelectric properties are improved.
Subjects: Materials Science >> Materials Science (General) submitted time 2022-10-21 Cooperative journals: 《桂林电子科技大学学报》
Abstract： In order to make the silicone material not only as a dielectric or substrate material in the flexible sensor, effective
methods were used to make it play a greater role in flexible sensing by having iontronic pressure sensing characteristics. By
modifying polydimethylsiloxane (PDMS), organic electrolyte was added to PDMS and doped with silica to obtain iontronic
pressure sensing characteristics, and the microscopic morphology of the material was observed. The mechanical and electrical
properties of the material were investigated by comparing the organic electrolyte content and surface roughness. Finally,
the ionic rubber consisting of PDMS, organic electrolyte, and silicon dioxide (the mass ratio is 2∶1∶0.3) possesses good mechanical
property with the Young's modulus of 1.1 MPa, and high sensitivity up to 1.46 nF/(kPa·cm2).
Subjects: Materials Science >> Materials Science (General) submitted time 2022-10-21 Cooperative journals: 《桂林电子科技大学学报》
Abstract： Aim at the problem of LiAlH4 exist excessive hydrogen release temperature and slow hydrogen release kinetics as
hydrogen storage material, a modification method that preparing NiTiO3 and doping it into LiAlH4through mechanical ball
milling was proposed. The effect of NiTiO3 on dehydrogenation properties of LiAlH4 were studied by temperature programmed
desorption and isothermal desorption experiments, and the results show that the initial hydrogen release temperature
of the LiAlH4 doped with w(NiTiO3)=6% decreases to 73 ℃, reduced by 120 ℃ compared to pristine LiAlH4; in isothermal
hydrogen release test, the LiAlH4 of doping 6 wt% NiTiO3 at 180 ℃ can release w(H2)=4.70% in 60 min, pristine
LiAlH4 hardly release hydrogen under the same conditions. The results show activation energy of dehydrogenation of w
(NiTiO3)=6% LiAlH4 decreases to 71.56 kJ/mol for the first step and 122.49 kJ/mol for the second step, indicating for
improving the kinetic performance of hydrogen release. Through XRD analysis, ball milling process destroy stability of Ni-
TiO3 and make it amorphization, while amorphous NiTiO3 can provide active sites and increase hydrogen diffusion channels
for dehydrogenation reaction of LiAlH4. The experimental results show that the modification method doping NiTiO3 effectively
improve dehydrogenation properties of LiAlH4.
Subjects: Electronics and Communication Technology >> Other Disciplines of Electronics and Communication Technology submitted time 2022-10-21 Cooperative journals: 《桂林电子科技大学学报》
Abstract： To enhance the device-performance and long-term stability of printable mesoscopic perovskite solar cells (MPSCs),
an anion-cation synergistic strategy is proposed to introduce the ionic liquid additive 1-ethyl-3-methylimidazolium acetate
(EMIMAC) into the perovskite active layer and use it for the preparation of efficient and stable MPSCs. The experimental
results indicate that the imidazole (EMIM+ ) cation enables ionic defect passivation (e.g., Pb2+ and PbI3- ) through
the coordination effect, which is believed to be beneficial for perovskite crystallization. On the other hand, the acetate
(AC- ) anion tends to coordinate with TiO2 to passivate the oxygen vacancy defects on the TiO2 surface for improved interfacial
contact at the TiO2/perovskite interface. As a result, the synergistic effects of the EMIM+ cation and AC- anion in
the EMIMAC achieves better perovskite crystallinity, more efficient charge transport, and lower nonradiative recombination.
The power conversion efficiency (PCE) of the MPSCs increased from 13.83% to 15.48%, accompanied by a negligible
hysteresis. Furthermore, the unencapsulated MPSCs exhibited excellent long-term stability by maintaining 90% of the initial
PCE after exposure in air (RH=50±5%) for 60 days. The experimental results indicate that the ionic liquid additive
EMIMAC can effectively enhance the PCE and stability of the device, providing an effective strategy for further improving
the device-performance.
Subjects: Materials Science >> Materials Chemistry submitted time 2022-10-19 Cooperative journals: 《桂林电子科技大学学报》
Abstract： On the basis of solid phase sintering to prepare single-phase Sr2Bi2O5, a series of CdS/Sr2Bi2O5 composite photocatalytic materials were prepared by chemical precipitation method to solve the problem of organic pollutants in environmental
pollution. The composite photocatalyst was characterized by XRD, SEM, TEM, EDS and XPS, and its photocatalytic performance was evaluated by degrading MB. After experiments, it is found that the CdS/Sr2Bi2O5 composite photocatalyst consists of two phases: CdS and Sr2Bi2O5. The morphology of agglomerated Sr2Bi2O5 particles is attached to the irregular CdS particles, and the surface of the two phases are in close contact with each other, forming an obvious boundary, and forming a heterojunction. When CdS/Sr2Bi2O5 mole ratio is 1/1, the visible photocatalytic performance is the best, the degradation efficiency of MB reached 95% in 40min, and three cycle tests show that the photocatalyst had good stability and repeatability.The significantly improved photocatalytic performance is mainly attributed to the formation of heterojunction between CdS and Sr2Bi2O5 phases in the composite photocatalyst, which accelerates the separation of photoelectron-generated hole pairs and effectively inhibits the recombination of photoelectron-generated hole pairs.
Subjects: Materials Science >> Materials Mechanics submitted time 2022-10-19 Cooperative journals: 《桂林电子科技大学学报》
Abstract： For exploring the effect of bimetallic co-doping on the hydrogen storage performance of MgH2 hydrogen storage materials, the thermodynamic stability and bonding mechanism of (Fe+Co) co-doping MgH2 hydrogen storage materials system were systematically studied by using first-principles calculations based on density functional theory.The lattice structure of the co-doped system was investigated,and found that the volume of Mg12Fe2Co4H36 and M-g12Fe4Co2H36 cell structure shrank by 16% and 17.5% respectively after (Fe+Co) co-doping .The formation enthalpy of the (Fe+Co) co-doping system was calculated, the calculated results reveal that the formation enthalpy of the system decreases after doping, which is more conducive to the resolution of hydrogen. The charge transfer of Fe and Co before and after doping and the bonding orbital between the metal atom and the hydrogen atom were investigated by calculating the Bader charge and electron density of states of the doping system, the analysis of the electronic structure proved that the electron transfer from the hydrogen atom to the magnesium atom after doping, which is beneficial to the weakening of the Mg—H bond. The (Fe+Co) bimetallic co-doping has a positive effect on the improvement of thermodynamic properties of MgH2 hydrogen storage materials, which provides theoretical guidance for the development of high-performance hydrogen storage materials.
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. submitted time 2022-10-19 Cooperative journals: 《桂林电子科技大学学报》
Abstract： In order to improve the efficiency of fluid calculations and ensure the accuracy of the results,the CUDA programming
platform and the powerful floating-point computing capabilities of the GPU are used to accelerate the Poisseuille flow
simulation calculation based on the lattice Boltzmann method.Two different addressing methods,linear addressing and subscript
addressing are designed,these two addressing methods are respectively applied to the lattice point collision,migration
flow,and macroscopic calculation of the lattice Boltzmann program,then discuss the influence of two addressing methods on
the calculation efficiency of the program. At the same time,unified memory management is used in the program,and the variables
opened up in this way can be used on the host side and the device side at the same time,which simplifies the code complexity
and reduces the consumption of frequently opening up memory for variables.Using Intel(R) Xeon(R) E-52620 v4
CPU and Nvidia Quadro GP100GPU for calculations,the linear addressing method and the subscript addressing method have
obtained 71 times and 25 times the speedup ratio of CPU serial code respectively.
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