scholarly journals Evidence of Phase Transitions and Their Role in the Transient Behavior of Mechanical Properties and Low Temperature Degradation of 3Y-TZP Made from Stabilizer-Coated Powder

Ceramics ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 271-285 ◽  
Author(s):  
Frank Kern
Keyword(s):  
Low Temperature ◽  
Tetragonal Phase ◽  
Sintering Temperature ◽  
Domain Size ◽  
Transient Behavior ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Fine Grain ◽  
Yttria Content ◽  
Temperature Ageing

The substance 3 mol% yttria stabilized zirconia (3Y-TZP) has become a commodity for the manufacture of components in biomedical and engineering applications. Materials made from stabilizer-coated rather than co-precipitated starting powders are known for their superior toughness and low temperature ageing resistance. The reason for this phenomenon is however still not fully understood. In this study, 3Y-TZP materials hot pressed at 1300–1450 °C for 1 h were characterized. It was found that at a sintering temperature of 1375 °C, a transition from fine grain to coarse grain microstructure associated with a shift from tough and ageing resistant to brittle and prone to ageing was observed. The detailed analysis of the phase composition by X-ray diffraction revealed that TZPs consists of up to five crystallographically different phases of zirconia simultaneously whose contents dynamically change with sintering temperature. At low sintering temperature, the predominant phases are a tetragonal phase with low yttria content and large domain size and high tetragonality together with a cubic phase of high yttria content. At high temperature, a tetragonal phase of higher yttria content and lower tetragonality is formed together with a cubic phase of lower yttria content.

scholarly journals Transport and Dielectric Properties of Mechanosynthesized La2/3Cu3Ti4O12 Ceramics

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 313
Author(s):  
Mohamad M. Ahmad ◽  
Hicham Mahfoz Kotb ◽  
Celin Joseph ◽  
Shalendra Kumar ◽  
Adil Alshoaibi
Keyword(s):  
Dielectric Constant ◽  
Sintering Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Boundary Conductivity ◽  
X Ray ◽  
Giant Dielectric ◽  
Mechanochemical Milling ◽  
Giant Dielectric Constant ◽  
Lower Temperature

La2/3Cu3Ti4O12 (LCTO) powder has been synthesized by the mechanochemical milling technique. The pelletized powder was conventionally sintered for 10 h at a temperature range of 975–1025 °C, which is a lower temperature process compared to the standard solid-state reaction. X-ray diffraction analysis revealed a cubic phase for the current LCTO ceramics. The grain size of the sintered ceramics was found to increase from 1.5 ± 0.5 to 2.3 ± 0.5 μm with an increase in sintering temperature from 975 to 1025 °C. The impedance results show that the grain conductivity is more than three orders of magnitude larger than the grain boundary conductivity for LCTO ceramics. All the samples showed a giant dielectric constant (1.7 × 103–3.4 × 103) and dielectric loss (0.09–0.17) at 300 K and 10 kHz. The giant dielectric constant of the current samples was attributed to the effect of internal barrier layer capacitances due to their electrically inhomogeneous structure.

Study on stabilization of cubic Li7La3Zr2O12 by Ge substitution in various atmospheres

2016 ◽  
Vol 09 (06) ◽  
pp. 1642005 ◽  
Author(s):  
Masashi Kotobuki ◽  
Binngong Yan ◽  
Li Lu ◽  
Emil Hanc ◽  
Joanna Molenda
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Tetragonal Phase ◽  
The Other ◽  
Cubic Phase ◽  
Other Hand ◽  
High Temperature Xrd ◽  
Li Ion

Stabilization of high Li ion conductive cubic Li7La3Zr2O[Formula: see text] (LLZ) by Ge substitution in air, N2/O2 and N2 atmospheres are studied by high temperature XRD (HT-XRD) of Ge-added tetragonal LLZ (Ge-LLZ). A formation of low temperature cubic phase caused by CO2 absorption during storage of the Ge-LLZ is observed at about 160[Formula: see text]C in all atmospheres. Additionally, impurity formation of La2Zr2O7 and La2O3 also occurs in all atmospheres. On the other hand, stabilization of cubic phase by substitution of Ge is largely influenced by the atmosphere. The cubic phase is observed at 40[Formula: see text]C after heating Ge-LLZ to 700[Formula: see text]C in air while only tetragonal phase appeared after heating in N2/O2. It is concluded that the heating atmosphere largely influences substitution of Ge, resulting in stabilization of the high Li ion conductive cubic phase.

A new low-loss microwave dielectric ceramic for low temperature cofired ceramic applications

2010 ◽  
Vol 25 (7) ◽  
pp. 1235-1238 ◽  
Author(s):  
Huanfu Zhou ◽  
Xiuli Chen ◽  
Liang Fang ◽  
Dongjin Chu ◽  
Hong Wang
Keyword(s):  
Dielectric Properties ◽  
Low Temperature ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Microwave Dielectric Ceramic ◽  
X Ray Diffraction ◽  
Low Loss ◽  
Dielectric Ceramic ◽  
X Ray ◽  
Microwave Dielectric

A new low sintering temperature microwave dielectric ceramic, Li2ZnTi3O8, was investigated. X-ray diffraction data show that Li2ZnTi3O8 has a cubic structure [P4332(212)] with lattice parameters a = 8.37506 Å, V = 587.44 Å3, and Z = 4 when the sintering temperature is 1050 °C. The Li2ZnTi3O8 ceramic exhibits good microwave dielectric properties with εr about 26.2, Q×f value about 62,000 GHz, and τf about −15 ppm/°C. The addition of BaCu(B2O5) can effectively lower the sintering temperature from 1050 to 900 °C without degrading the microwave dielectric properties. Compatibility with Ag electrode indicates this material can be applied to low temperature cofired ceramic devices.

Low-temperature crystal structure of RS-thiocamphor

2004 ◽  
Vol 219 (9) ◽  
Author(s):  
E. Louise R. Robins ◽  
Michela Brunelli ◽  
Asiloé J. Mora ◽  
Andrew N. Fitch
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Two Phase ◽  
X Ray ◽  
Low Temperature Crystal Structure

AbstractDSC and high-resolution powder X-ray diffraction measurements in the range 295 K–100 K show that RS-thiocamphor undergoes two phase transitions. The first, at around 260 K on cooling, is from the room-temperature body-centred-cubic phase to a short-lived intermediate. At 258 K the low-temperature form starts to appear. The crystal structure of the latter is orthorhombic, space group

A low temperature phase of (NH4)2TeBr6

1969 ◽  
Vol 47 (22) ◽  
pp. 4288-4289 ◽  
Author(s):  
A. K. Das ◽  
I. D. Brown
Keyword(s):  
Low Temperature ◽  
Tetragonal Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Low Temperature Phase

X-Ray diffraction has shown the existence of a low temperature tetragonal phase of (NH4)2TeBr6 having space group P4/mnc(D4h6) with a = 7.501, c = 10.765 Å.

Preparation and Characterization of (1-x)BiScO3-xPbTiO3 Ceramics by Two-Step Sintering

2008 ◽  
Vol 368-372 ◽  
pp. 8-10 ◽  
Author(s):  
Ting Ting Zou ◽  
Xiao Hui Wang ◽  
Long Tu Li
Keyword(s):  
Grain Size ◽  
Low Temperature ◽  
High Performance ◽  
Piezoelectric Properties ◽  
Sintering Temperature ◽  
Sintering Aid ◽  
Potential Approach ◽  
Fine Grain ◽  
Sintering Method

High-performance fine-grain (1-x)BiScO3-xPbTiO3 ceramics were prepared by two-step sintering method. Influences of sintering temperature, holding time, and composition on the microstructure and properties were discussed. The BSPT ceramics obtained via two-step sintering reaches density higher than 95% at a low temperature of 800°C without any sintering aid, and the grain size of the ceramics is also effectively controlled. Excellent piezoelectric properties between the composition of x=0.63 and x=0.64 reveals a probable MPB in this range, suggesting a potential approach to pursue high performance BSPT ceramics.

Variable temperature and high-pressure crystal chemistry of perovskite formamidinium lead iodide: a single crystal X-ray diffraction and computational study

2017 ◽  
Vol 53 (54) ◽  
pp. 7537-7540 ◽  
Author(s):  
Shijing Sun ◽  
Zeyu Deng ◽  
Yue Wu ◽  
Fengxia Wei ◽  
Furkan Halis Isikgor ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Low Temperature ◽  
Tetragonal Phase ◽  
Computational Study ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
Lead Iodide ◽  
X Ray ◽  
Tetragonal Phase Transition

Single crystals of [(NH2)2CH]PbI3 undergo a cubic-to-tetragonal phase transition at low temperature and high pressure.

X-ray diffraction study of the phase transition of K2Mn2(BeF4)3: a new type of low-temperature structure for langbeinites

2001 ◽  
Vol 57 (3) ◽  
pp. 221-230 ◽  
Author(s):  
A. Guelylah ◽  
G. Madariaga ◽  
V. Petricek ◽  
T. Breczewski ◽  
M. I. Aroyo ◽  
...  
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Mode Analysis ◽  
Cubic Phase ◽  
Temperature Phase ◽  
Temperature Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Type ◽  
Low Temperature Phase

The potassium manganese tetrafluoroberyllate langbeinite compound has been studied in the temperature range 100–300 K. Using DSC measurements, a phase transition has been detected at 213 K. The space group of the low-temperature phase was determined to be P1121 using X-ray diffraction experiments and optical observations of the domain structure. The b axis is doubled with respect to the prototypic P213 cubic phase. Lattice parameters were determined by powder diffraction data [a = 10.0690 (8), b = 20.136 (2), c = 10.0329 (4) Å, γ = 90.01 (1)°]. A precise analysis of the BeF4 tetrahedra in the low-temperature phase shows that two independent tetrahedra rotate in opposite directions along the doubled crystallographic axis. A symmetry mode analysis of the monoclinic distortion is also reported. This is the first report of the existence of such a phase transition in K2Mn2(BeF4)3 and also of a new type of low-temperature structure for langbeinite compounds.

EFFECT OF Co3O4 NANOPARTICLE ON THE PROPERTY OF BARIUM TITANATE CERAMIC

2011 ◽  
Vol 01 (02) ◽  
pp. 229-235 ◽  
Author(s):  
W. C. VITTAYAKORN ◽  
D. BUNJONG ◽  
A. RUANGPHANIT ◽  
N. VITTAYAKORN
Keyword(s):  
Barium Titanate ◽  
Dielectric Behavior ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Cell Parameters ◽  
Fine Grain ◽  
Barium Titanate Ceramic ◽  
Lower Temperature ◽  
Titanate Ceramics ◽  
Titanate Ceramic

Effects of the Co3O4 nanoparticle on the phase formation, microstructure and dielectric properties of barium titanate ceramics are investigated in this study. Co3O4 -doped BaTiO3 ceramics were prepared by the conventional mixed oxide method followed by normal sintering in air. Systematic studies of X-ray diffraction (XRD), scanning electron microscopy and dielectric spectroscopy with varying doping levels were performed. The cell parameters, tetragonality and crystallite size of doped ceramics also were calculated from XRD data. Results showed that the single phase of BaTiO3 gave no evidence of unwanted peak forms in any of the samples. Cubic phase occurred after adding Co3O4 at 0.25 mol%. Various grain sizes and shapes were found in this system. Finally, adding Co3O4 in BaTiO3 ceramics resulted in shifting of the Curie point to a lower temperature. The composition, x = 0.25, showed different dielectric behavior, which related to appearance of the cubic phase and fine grain microstructure.

Crack Growth by the Isothermal Martensitic Phase Transformation in Tetragonal Zirconia Polycrystals

2013 ◽  
Vol 738-739 ◽  
pp. 537-541
Author(s):  
Kyu Hong Hwang ◽  
Jong Kook Lee
Keyword(s):  
Phase Transformation ◽  
Low Temperature ◽  
Sintered Density ◽  
Crack Nucleation ◽  
Tetragonal Zirconia ◽  
Surface Cracks ◽  
Yttria Content ◽  
Initial Stage ◽  
Temperature Ageing ◽  
Crack Nucleation And Growth

In this study, we investigated the crack nucleation and growth and propagation on the surface of Y-TZP during isothermal phase transformation by low temperature ageing. Crack initiation and growth on the surface of Y-TZP specimen was dependent on the sintered microstructure, i.e, sintered density, grain size, pore structure, residual stress etc.. In the case of Y-TZP with 2mol % yttria content, phase transformation of tetragonal to monoclinic began on the surface and induced a crack nucleation of specimen at the initial stage of low temperature ageing. Most of cracks in 2Y-TZP by low temperature ageing were firstly formed on the surface of specimens (free surface, weak bonding grains, etc.) where the change of strain free energy for a tetragonal to monoclinic transformation was small, and surface cracks grew into the bulk interior through the grain boundaries.

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