Structure and Properties of Hydrogen-Charged Electrochromic Nb2O5 Ceramics

2009 ◽  
Vol 79-82 ◽  
pp. 1619-1622
Author(s):  
Ming Jian Ding ◽  
Wan Ping Chen ◽  
Yan Hong Gu ◽  
Yu Wang
Keyword(s):  
Crystal Structure ◽  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Interstitial Site ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Charging ◽  
Naoh Solution ◽  
Type Conduction

Nb2O5 ceramic pellets were prepared through sintering and hydrogen was introduced into Nb2O5 pellets through a process known as electrochemical hydrogen charging, in which Nb2O5 acted as the cathode in a 0.01 M NaOH solution. The color of Nb2O5 was found dramatically darkened after the treatment while X-ray diffraction indicated that there was no change in the crystal structure. I-V and R-T measurements showed that the resistivity was greatly decreased after hydrogen charging and the resistivity exhibited a negative-temperature-coefficient (NTC). It was proposed that hydrogen can be incorporated into Nb2O5 lattice and occupies at some interstitial site. Nb5+ of Nb2O5 is partially reduced to Nb4+ by hydrogen and the NTC-type conduction results from electron transfer between Nb5+ and Nb4+ through a hopping mechanism.

Aging of iron manganite negative temperature coefficient thermistors

1998 ◽  
Vol 13 (5) ◽  
pp. 1238-1242 ◽  
Author(s):  
T. Battault ◽  
R. Legros ◽  
A. Rousset
Keyword(s):  
Temperature Coefficient ◽  
Spinel Structure ◽  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Octahedral Sites ◽  
Before And After ◽  
Structural Equilibrium ◽  
Electrical Data

“Aging,” defined as the drift of resistance with temperature after 1000 h, was investigated for iron manganite temperature coefficient thermistors. For these devices, aging is relatively large, about 10%. The cationic distributions before and after aging were determined by Mössbauer spectroscopy. These distributions explain all the x-ray diffraction and correlated electrical data. The origin of the aging observed on iron manganites thermistors has been identified. It is due to the migration of Fe3+ ions from tetrahedral to octahedral sites of the spinel structure in order to reach a structural equilibrium.

Preparation and Characterizations of Novel Near Room-Temperature Driven Fe/Sr2Bi2O5 Thermocatalyst

2014 ◽  
Vol 804 ◽  
pp. 63-66
Author(s):  
Pei Wu ◽  
Xue Gang Luo ◽  
Xiao Yan Lin ◽  
Ke Li
Keyword(s):  
Room Temperature ◽  
Negative Temperature Coefficient ◽  
Removal Rate ◽  
Negative Temperature ◽  
X Ray Diffraction ◽  
Total Removal ◽  
Solid State Method ◽  
X Ray ◽  
Conventional Solid State Method ◽  
Molar Percent

In this study, room-temperature driven thermocatalyst (Fe/Sr2Bi2O5 powder) with negative temperature coefficient resistor (NTC) characteristics was prepared by conventional solid state method at various temperatures. Fe/Sr2Bi2O5 powder was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy EDS. The results indicate that Fe/Sr2Bi2O5 powder was prepared and the Fe has been doped successfully in Sr2Bi2O5. The thermocatalyst powder obtained a particular and stable crystal style, meanwhile, besides, well distributed size and rough surface were also found in regard to the thermocatalyst above. On the other hand, the thermocatalyst reactions show that Fe/Sr2Bi2O5 powder has highest removal rate of degradation under the 0.75% (molar percent) content of Fe at 750 oC. The total removal rate of degradation arrives at 93.8% after 3h at 50 oC. Hence, Fe/Sr2Bi2O5 powder may be a potential thermocatalyst at room-temperature for wastewater treatment in the future.

scholarly journals Effect of Al3+ Substitution On Magnetic and DC Electrical Resistivity Properties of NiZnCu Nanoferrites

2021 ◽  
Author(s):  
N MURALI
Keyword(s):  
Electrical Resistivity ◽  
Negative Temperature Coefficient ◽  
Sol Gel ◽  
Combustion Process ◽  
Negative Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Auto Combustion ◽  
Ft Ir ◽  
Resultant Material

Abstract Al substituted Ni0.4Zn0.35Cu0.25Fe2-xAlxO4 (x = 0.00, 0.05, 0.10, 0.15, 0.20) samples is synthesized using the sol-gel auto-combustion process. X-ray diffraction shows its cubic spinel structure. The lattice constant decreases as the Al3+ content increases. The sizes of the crystallites are also decreasing in the range of 32.15 nm to 22.89 nm. The wavenumbers of tetrahedral and octahedral sites sighted in the FT-IR spectra are similar to that of the precursor. The increment in the Al3+ content increases the DC conductivity. The electrical resistivity decrease with an increase in the temperature, i.e., it has a negative temperature coefficient with resistance similar to semiconductors. VSM results show their isotropic nature forming single domain ferrimagnetic particles. The resultant material is widely significant, as indicated by its result.

High-pressure Synthesis, Crystal Structure, and Properties of the First Ternary Zirconium Borate β-ZrB2O5

2008 ◽  
Vol 63 (6) ◽  
pp. 707-712 ◽  
Author(s):  
Johanna S. Knyrim ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Room Temperature ◽  
High Pressure Phase ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Pressure Synthesis ◽  
Pressure Phase

The high-pressure phase β -ZrB2O5 represents the first ternary borate in the system Zr-B-O. The compound was synthesized under high-pressure / high-temperature conditions of 7.5 GPa and 1100 °C in a Walker-type multianvil apparatus. The crystal structure was determined on the basis of single crystal X-ray diffraction data, collected at room temperature. The monoclinic zirconium borate crystallizes in the space group P21/c with the lattice parameters a = 439.04(9), b = 691.2(2), c = 896.8(2) pm, and β = 90.96(3)°. The structure is isotypic to the high-pressure phase β -HfB2O5, which is built up from layers of exclusively corner-sharing BO4 tetrahedra. Between these layers, the cations are coordinated square-antiprismatically by eight oxygen atoms.

Electrical and Magnetic Properties of Pb0.8La0.2Fe0.1Cr0.1Ti0.8O3

2019 ◽  
Vol 201 (1) ◽  
pp. 43-54
Author(s):  
Amrita Nayak ◽  
S. K. Patri ◽  
P. L. Deepti ◽  
B. Behera
Keyword(s):  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Polycrystalline Sample ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
Phase Transition Temperatures ◽  
Different Temperatures

The dielectric spectroscopy of a new ceramic material; Pb0.8La0.2Fe0.1Cr0.1Ti0.8O3 has been studied. The compound was prepared by solid-state reaction method. The structural study from X-ray diffraction technique shows the formation of polycrystalline sample with orthorhombic crystal system at room temperature. Dielectric property of this material has been characterized in the temperature range of 25–450°C and frequency range of 100 Hz – 1 MHz respectively. The phase transition temperatures were at two different temperatures for each frequency. The nature of ac conductivity shows the negative temperature coefficient of resistance type behavior of the material.

Effects of Cd and Cd-Cu Doping on the Microstructure and Electrical Properties of NiMnCoO NTC Ceramics

2011 ◽  
Vol 236-238 ◽  
pp. 1632-1635 ◽  
Author(s):  
Guo Na ◽  
Ya Dong Li
Keyword(s):  
Electrical Properties ◽  
Room Temperature ◽  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
High Thermal Stability ◽  
X Ray Diffraction ◽  
Solid Reaction ◽  
Cu Doping ◽  
X Ray ◽  
Cd Doping

The precursors of CdxNi1-xCo0.2Mn1.8O4(x=0,0.1,0.2,0.3) and Cd0.2Cu0.1Ni0.7Co0.2Mn1.8O4negative temperature coefficient (NTC) ceramics were prepared at room temperature by the solid reaction. These precursors were calcined and then sintered in air at 1100°C. Influence of the Cd and Cd-Cu doping on the microstructure and electrical properties of the NTC ceramics were investigated by X-ray diffraction and SEM technique. The results showed that Cd doping was conducive to reduce the grain size, increase density, and obtain high thermal stability.

Impact of the anion and chalcogen on the crystal structure and properties of 4,6-dimethyl-2-pyrimido(thio)nium halides

2020 ◽  
Vol 76 (5) ◽  
pp. 468-475
Author(s):  
Andrzej Okuniewski ◽  
Damian Rosiak ◽  
Jarosław Chojnacki
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Hydrogen Bonds ◽  
Luminescent Properties ◽  
Structural Motif ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Chloride Monohydrate

By the reaction of urea or thiourea, acetylacetone and hydrogen halide (HF, HBr or HI), we have obtained seven new 4,6-dimethyl-2-pyrimido(thio)nium salts, which were characterized by single-crystal X-ray diffraction, namely, 4,6-dimethyl-2-oxo-2,3-dihydropyrimidin-1-ium bifluoride, C6H9N2O+·HF2 − or (dmpH)F2H, 4,6-dimethyl-2-oxo-2,3-dihydropyrimidin-1-ium bromide, C6H9N2O+·Br− or (dmpH)Br, 4,6-dimethyl-2-oxo-2,3-dihydropyrimidin-1-ium iodide, C6H9N2O+·I− or (dmpH)I, 4,6-dimethyl-2-oxo-2,3-dihydropyrimidin-1-ium iodide–urea (1/1), C6H9N2O+·I−·CH4N2O or (dmpH)I·ur, 4,6-dimethyl-2-sulfanylidene-2,3-dihydropyrimidin-1-ium bifluoride–thiourea (1/1), C6H9N2S+·HF2 −·CH4N2S or (dmptH)F2H·tu, 4,6-dimethyl-2-sulfanylidene-2,3-dihydropyrimidin-1-ium bromide, C6H9N2S+·Br− or (dmptH)Br, and 4,6-dimethyl-2-sulfanylidene-2,3-dihydropyrimidin-1-ium iodide, C6H9N2S+·I− or (dmptH)I. Three HCl derivatives were described previously in the literature, namely, 4,6-dimethyl-2-oxo-2,3-dihydropyrimidin-1-ium chloride, (dmpH)Cl, 4,6-dimethyl-2-sulfanylidene-2,3-dihydropyrimidin-1-ium chloride monohydrate, (dmptH)Cl·H2O, and 4,6-dimethyl-2-sulfanylidene-2,3-dihydropyrimidin-1-ium chloride–thiourea (1/1), (dmptH)Cl·tu. Structural analysis shows that in 9 out of 10 of these compounds, the ions form one-dimensional chains or ribbons stabilized by hydrogen bonds. Only in one compound are parallel planes present. In all the structures, there are charge-assisted N+—H...X − hydrogen bonds, as well as weaker CAr +—H...X − and π+...X − interactions. The structures can be divided into five types according to their hydrogen-bond patterns. All the compounds undergo thermal decomposition at relatively high temperatures (150–300 °C) without melting. Four oxopyrimidinium salts containing a π+...X −...π+ sandwich-like structural motif exhibit luminescent properties.

High-Pressure Synthesis, Crystal Structure, And Properties Of δ-Ce(Bo2)3

2007 ◽  
Vol 62 (6) ◽  
pp. 759-764 ◽  
Author(s):  
Almut Haberer ◽  
Gunter Heymann ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Diffraction Data ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Pressure Synthesis ◽  
Pressure Phase

The cerium meta-oxoborate δ -Ce(BO2)3 was synthesized under high-pressure / high-temperature conditions of 3.5 GPa and 1050 °C in a Walker-type multianvil apparatus. The crystal structure was determined by single crystal X-ray diffraction data, collected at r. t. The compound crystallizes monoclinicly in the space group P21/c with the lattice parameters a = 422.52(8), b = 1169.7(2), c = 725.2(2) pm, and β = 91.33(3)°. The structure is isotypic to the recently published high-pressure phase δ -La(BO2)3, consisting exclusively of corner sharing [BO4]5− tetrahedra

scholarly journals Effect of Cu Substitution on Magnetic and DC Electrical Resistivity Properties of Ni-Zn Nano Ferrites

2021 ◽  
Author(s):  
K. Chandramouli ◽  
P. Anantha Rao ◽  
B. Suryanarayana ◽  
Vemuri Raghavendra ◽  
D. Parajuli ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Negative Temperature Coefficient ◽  
Sol Gel ◽  
Combustion Process ◽  
Negative Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cu Content ◽  
Auto Combustion ◽  
Resultant Material

Abstract Cu substituted Ni0.5Zn0.5-xCuxFe2O4 (x = 0, 0.1, 0.2, 0.3 and 0.4) samples is synthesized using the sol-gel auto-combustion process. X-ray diffraction shows its cubic spinel structure. The lattice constant decreases as the Cu content increases. The sizes of the crystallites are also decreasing in the range of 42.68 nm to 21.75 nm. The wavenumbers of tetrahedral and octahedral sites sighted in the FTIR spectra are similar to that of the precursor. The increment in the copper content increases the DC conductivity. The electrical resistivity decrease with increase in the temperature, i.e. it has a negative temperature coefficient with resistance similar to semiconductors. The remnant ratios R obtained from VSM show their isotropic nature forming single domain ferrimagnetic particles. The resultant material is widely significant, as indicated by its result.

scholarly journals Comprehensive investigation of structural, dielectric and local piezoelectric properties of KNN ceramics

2019 ◽  
Vol 09 (02) ◽  
pp. 1950016 ◽  
Author(s):  
Poonam Kumari ◽  
Madan Lal ◽  
Sunil Kumar ◽  
Radheshyam Rai ◽  
Anupinder Singh ◽  
...  
Keyword(s):  
Negative Temperature Coefficient ◽  
Piezoelectric Properties ◽  
Negative Temperature ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Temperature Coefficient Of Resistance ◽  
X Ray ◽  
Ceramic Samples ◽  
Free Ion ◽  
Diffraction Patterns

In this research paper, we utilized the traditional high-temperature solid-state reaction method to fabricate the K[Formula: see text]Na[Formula: see text]NbO3, K[Formula: see text]Na[Formula: see text]NbO3 and K[Formula: see text]Na[Formula: see text]NbO3 (abbreviated as KNN-1, KNN-2, and KNN-3, respectively) lead-free ion deficient ceramics for understanding the influence of ionic deficiency on the crystalline structure and dielectric/piezoelectric properties of the samples. X-ray diffraction patterns of these samples exhibited a perovskite tetragonal phase. Dielectric anomalies around 287∘C and 471∘C were identified as ferroelectric to ferroelectric and ferroelectric to paraelectric-transition temperatures for KNN-2 at 1[Formula: see text]kHz. It was found that the composition KNN-2 exhibit relatively high Curie temperature i.e., 471∘C. The conductivity plots confirm that the activation energies are frequency-dependent. The impedance behavior in our ceramic samples can be analyzed with the bulk/grain effect. The slope of [Formula: see text] with temperature shows negative temperature coefficient of resistance (NTCR) type behavior in proposed KNN ceramics material.

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