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Title: Phase-change sintering of BaCl 2 transparent ceramics

Publication Date:
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
OSTI Identifier:
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Alloys and Compounds
Additional Journal Information:
Journal Volume: 705; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 21:34:29; Journal ID: ISSN 0925-8388
Country of Publication:

Citation Formats

Shoulders, W. Taylor, and Gaume, Romain M. Phase-change sintering of BaCl 2 transparent ceramics. Netherlands: N. p., 2017. Web. doi:10.1016/j.jallcom.2017.02.071.
Shoulders, W. Taylor, & Gaume, Romain M. Phase-change sintering of BaCl 2 transparent ceramics. Netherlands. doi:10.1016/j.jallcom.2017.02.071.
Shoulders, W. Taylor, and Gaume, Romain M. Mon . "Phase-change sintering of BaCl 2 transparent ceramics". Netherlands. doi:10.1016/j.jallcom.2017.02.071.
title = {Phase-change sintering of BaCl 2 transparent ceramics},
author = {Shoulders, W. Taylor and Gaume, Romain M.},
abstractNote = {},
doi = {10.1016/j.jallcom.2017.02.071},
journal = {Journal of Alloys and Compounds},
number = C,
volume = 705,
place = {Netherlands},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.jallcom.2017.02.071

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  • Compaction of specimens consisting of 70% Al{sub 2}O{sub 3} and 30% of ZrO{sub 2}(2Y{sub 2}O{sub 3}) has been studied during UHF sintering and furnace heating (FH). Kinetics of the change in density and pore size distribution at 1500 and 1600{degrees}C have been studied. The compaction rate is higher with UHF heating than with FH over the whole range of temperature and exposure time. Retention of small pores with UHF heating for a long time supports the high level of capillary forces and promotes ceramic material compaction.
  • High-density tetragonal zirconia, partially stabilized with Y{sub 2}O{sub 3}, produced by low-temperature T < 1600{degrees}C sintering is characterized by exceptionally high strength and fracture toughness ({sigma}{sub bend}{approx}2300 MPa, K{sub Ic} {approx}15 MPa {center_dot}m{sup 1/2}). However, the properties of this material depend strongy on temperature: as the temperature increases to 800 {degrees}C the strength and toughness rapidly decrease. On the other hand, it is well known that sintering at temperatures higher than 2100 {degrees}C (in the area of formation of the cubic phase) makes it possible to produce ceramics whose mean strength and fracture toughness value {sigma}{sub bend} = 400-800 MPa,more » K{sub Ic} {approx}7 MPa{center_dot}m{sup 1/2} remain constant to 1000{degrees}C. The cooling rate after sintering in the region of the cubic phase has a strong effect on the phase composition of the material. In rapid cooling the cubic phase of ZrO{sub 2} undergoes diffisionless transformation to the so-called T{prime}-phase, which differs from T-ZrO{sub 2} by a large amount of dissolved Y{sub 2}O{sub 3} and a low degree of tetragonality. Slow cooling leads to the formation of precipitates of the tetragonal phase in the cubic phase by the diffusion mechanism. There are almost no data on the properties of ZrO{sub 2}-3 % (mol) Y{sub 2}O{sub 3} ceramics produced by sintering in the two-phase (K + T) region at temperatures above 1600{degrees}C. The aim of this work was to study the mechanical properties and phase composition of the above oxides after high temperature vacuum sintering.« less
  • The presence of BaCl2 nanocrystals and the crystallographic phase that they adopt controls the optical behavior of fluorochlorozirconate glass-ceramics. We have used in situ X-ray diffraction heating experiments and ex situ transmission electron microscopy to follow the BaCl2 nanocrystal nucleation and growth processes as a function of heating rate and isothermal hold temperature. The BaCl2 nanocrystals nucleate with the hexagonal crystal structure and grow as spherical particles to a size of similar to 10 to 20nm. They then undergo a structural transformation to the orthorhombic phase and their shape changes to rounded disks, with diameters ranging from 150 to 250nm,more » and thicknesses ranging from 80 to 120nm. The change in size results from Ostwald ripening of the hexagonal BaCl2 nanocrystals to form the orthorhombic BaCl2 nanocrystals.« less
  • In this paper, the effect of the sintering temperature on the low-field dielectric behavior of nonstoichiometric Pb{sub 0.95}La{sub 0.05}(Fe{sub 2/3}W{sub 1/3}){sub 0.65}Ti{sub 0.35}O{sub 3} relaxor ferroelectrics is investigated. The x-ray patterns and the scanning electron microscope images are used to detect the pyrochlore phase and the perovskite structure. The electric properties of the resistivity, the space charge polarization, the temperature-dependent dielectric constant and dielectric loss are discussed. The diffused phase transition and the ordering state are fitted and discussed by using the empirical law and two ordering models. Furthermore, the glassy behavior is determined by using the Curie-Weiss law andmore » the spin-glass model. According to the experimental data and fitting results, the dielectric picture is changed from the short range order relaxorlike behavior to the long range order normal ferroelectric state as increasing the sintering temperature and the glassy behavior is weakened at the lowest and highest sintering temperature at which the pyrochlore phase PWO{sub 4} is induced. Therefore, it is suggested that the 1:1 ordered domain is enhanced by increasing the sintering temperature and the glassy behavior is related to not only the ordering degree also the polar defect pairs. For more ordering degree and polar defect pairs, the glassy is weakened and the correlation of neighboring polar microregions is enhanced.« less