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Author |
Dinger, J.; Friedrich, T.; Reimann, T.; Toepfer, J. |
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Title |
NiMn₂O₄ revisited : temperature-dependent cation distribution from in situ neutron diffraction and thermopower studies |
Type |
A1 Journal article |
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Year  |
2023 |
Publication |
Journal of the American Ceramic Society |
Abbreviated Journal |
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Volume |
106 |
Issue |
3 |
Pages |
1834-1847 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The cation distribution of the negative temperature coefficient (NTC) thermistor spinel NiMn2O4 was studied in the temperature range from 55 to 900 degrees C, using a combined in situ neutron diffraction and thermopower study. Rietveld refinements of in situ neutron diffraction data reveal a temperature dependence of the degree of inversion with an inversion parameter of 0.70(1) at 900 degrees C and 0.87(1) at 55 degrees C. Thermopower measurements were evaluated using a modified Heikes formula, and the [Mn4+]/[Mn3+] ratio on octahedral sites of the spinel structure was calculated considering spin and orbital degeneracy. The inversion degree and disproportionation parameter, determined independently as function of temperature, were used to calculate the cation distribution of NiMn2O4 in the whole temperature range. At high temperature, within the stability range of the spinel, the cation distribution is characterized by a moderate degree of inversion with a concentration of NiB2+${\mathrm{Ni}}\mathrm{B}< |
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Wos |
000880360600001 |
Publication Date |
2022-10-21 |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0002-7820 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
3.9 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 3.9; 2023 IF: 2.841 |
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Call Number |
UA @ admin @ c:irua:192087 |
Serial |
7326 |
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Author |
Zhang, S.; Sahin, H.; Torun, E.; Peeters, F.; Martien, D.; DaPron, T.; Dilley, N.; Newman, N. |
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Title |
Fundamental mechanisms responsible for the temperature coefficient of resonant frequency in microwave dielectric ceramics |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
Journal of the American Ceramic Society |
Abbreviated Journal |
J Am Ceram Soc |
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Volume |
100 |
Issue |
100 |
Pages |
1508-1516 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
The temperature coefficient of resonant frequency ((f)) of a microwave resonator is determined by three materials parameters according to the following equation: (f)=-(1/2 (epsilon) + 1/2 + (L)), where (L), (epsilon), and are defined as the linear temperature coefficients of the lattice constant, dielectric constant, and magnetic permeability, respectively. We have experimentally determined each of these parameters for Ba(Zn1/3Ta2/3)O-3, 0.8 at.% Ni-doped Ba(Zn1/3Ta2/3)O-3, and Ba(Ni1/3Ta2/3)O-3 ceramics. These results, in combination with density functional theory calculations, have allowed us to develop a much improved understanding of the fundamental physical mechanisms responsible for the temperature coefficient of resonant frequency, (f). |
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Place of Publication |
Columbus, Ohio |
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Wos |
000399610800034 |
Publication Date |
2017-02-14 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0002-7820 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.841 |
Times cited |
6 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 2.841 |
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Call Number |
UA @ lucian @ c:irua:143682 |
Serial |
4597 |
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Author |
Abakumov, A.M.; Hadermann, J.; Van Tendeloo, G.; Antipov, E.V. |
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Title |
Chemistry and structure of anion-deficient perovskites with translational interfaces |
Type |
A1 Journal article |
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Year |
2008 |
Publication |
Journal of the American Ceramic Society |
Abbreviated Journal |
J Am Ceram Soc |
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Volume |
91 |
Issue |
6 |
Pages |
1807-1813 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Place of Publication |
Columbus, Ohio |
Editor |
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Language |
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Wos |
000256410700010 |
Publication Date |
2008-04-29 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0002-7820;1551-2916; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.841 |
Times cited |
39 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.841; 2008 IF: 2.101 |
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Call Number |
UA @ lucian @ c:irua:70088 |
Serial |
355 |
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Author |
Fang, P.a.; Gu, H.; Wang, P.l.; Van Landuyt, J.; Vleugels, J.; Van der Biest, O.; |
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Title |
Effect of powder coating on stabilizer distribution in CeO2-stabilized ZrO2 ceramics |
Type |
A1 Journal article |
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Year |
2005 |
Publication |
Journal of the American Ceramic Society |
Abbreviated Journal |
J Am Ceram Soc |
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Volume |
88 |
Issue |
7 |
Pages |
1929-1934 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The phase and microstructure relationship of 12 mol% CeO2-stabilized ZrO2 ceramics prepared from coated powder was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersed Xray spectroscopy (EDS). As compared with the sample prepared with co-precipitated method, which exhibited a similar grain size distribution, the EDS analysis revealed that the powder coating induced a wide distribution of CeO2 solubility, which decreases monotonically with the increase of grain size. This variation of stabilizer content from grain to grain rendered many large grains in the monoclinic phase. Stronger cerium segregation to grain boundaries was observed between large grains, which often form thin amorphous films there. The inhomogeneous; CeO2 distribution keeps more tetragonal ZrO2 grains close to the phase boundary to facilitate the transforming toughness. Addition of an Al2O3 precursor in coated powders effectively raises the overall CeO2 stabilizer content in the grains and preserves more transformable tetragonal phase in the microstructure, which further enhanced the fracture toughness. The dependence of CeO2 solubility on grain size may be explained in a simple coating-controlled diffusion and growth process that deserves further investigation. |
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Place of Publication |
Columbus, Ohio |
Editor |
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Language |
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Wos |
000230128100040 |
Publication Date |
2005-06-23 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0002-7820;1551-2916; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.841 |
Times cited |
11 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.841; 2005 IF: 1.586 |
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Call Number |
UA @ lucian @ c:irua:103156 |
Serial |
830 |
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Author |
Bals, S.; Verbeeck, J.; Van Tendeloo, G.; Liu, Y.-L.; Grivel, J.-C. |
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Title |
Quantitative electron microscopy of (Bi,Pb)2Sr2Ca2Cu3O10+\delta/Ag multifilament tapes during initial stages of annealing |
Type |
A1 Journal article |
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Year |
2005 |
Publication |
Journal of the American Ceramic Society |
Abbreviated Journal |
J Am Ceram Soc |
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Volume |
88 |
Issue |
2 |
Pages |
431-436 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The microstructural and compositional evolution during initial annealing of a superconducting (Bi,Pb)(2)Sr2Ca2Cu3O10+delta/Ag tape is studied using quantitative transmission electron microscopy. Special attention is devoted to the occurrence of Pb-rich liquids, which are crucial for the Bi2Sr2CaCu2O8+delta to (Bi,Pb)(2)Sr2Ca2Cu3O10+delta transformation. Ca and/or Pb-rich (Bi,Pb)(2)Sr2CaCu2O8+delta grains dissolve into a liquid, which reacts with Ca-rich phases to increase the liquid's Ca-content. This leads to (Bi,Pb)(2)Sr2Ca2Cu3O10+delta formation. Apparently, a Ca/Sr ratio of around I is sufficient to keep (Bi,Pb)(2)Sr2Ca2Cu3O10+delta nucleation going. It is confirmed that Ag particles are transported from the Ag-sheath into the oxide core by the liquid and not by mechanical treatment of the tape. |
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Publisher |
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Place of Publication |
Columbus, Ohio |
Editor |
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Language |
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Wos |
000227510200030 |
Publication Date |
2005-02-16 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0002-7820;1551-2916; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.841 |
Times cited |
1 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.841; 2005 IF: 1.586 |
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Call Number |
UA @ lucian @ c:irua:54876UA @ admin @ c:irua:54876 |
Serial |
2754 |
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