Effect of preparation method on chemical stability of sinterable calcium doped lanthanum chromites

Natsuko Sakai; Tatsuya Kawada; Harumi Yokokawa; Masayuki Dokiya

Effect of preparation method on chemical stability of sinterable calcium doped lanthanum chromites

Natsuko Sakai, Tatsuya Kawada, Harumi Yokokawa, Masayuki Dokiya

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Abstract

The effect of preparation method on the chemical stability of sinterable (La,Ca)CrO_3-δ powder was investigated. The ceramic method (powder mixing method) resulted in inhomogeneous distributions of the calcium content (x) in the perovskite phase (La_1-xCa_xCrO_3-δ) after calcining at a temperature from 1223 to 1373 K. More homogeneous powder was obtained by the liquid mixing m method. The distribution of calcium content caused a large amount of second phases such as calcium oxychromates (Ca_m(CrO₄)_n) in a powder prepared by the ceramic method, and an excess amount of the second phase remained as Ca₅(CrO₄)₃OH on the surface of the ceramics after sintering at 1573 K. During a treatment in an H₂+H₂O gaseous mixture at 1273 K for 627 h, Ca_m(CrO₄)_n decomposed to CaO and α-CaCr₂O₄, and the decomposition was enhanced by the existence of silicon-containing impurities. The liquid mixing method minimized the amount of Ca_m(CrO₄)_n, and resulted in sufficient chemical stability in H₂+H₂O.

Original language	English
Pages (from-to)	1164-1169
Number of pages	6
Journal	Journal of the Ceramic Society of Japan. International ed.
Volume	101
Issue number	11
Publication status	Published - 1993 Nov 1
Externally published	Yes

ASJC Scopus subject areas

Engineering(all)

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@article{7f81bf80604645d8afa6bae373628c44,

title = "Effect of preparation method on chemical stability of sinterable calcium doped lanthanum chromites",

abstract = "The effect of preparation method on the chemical stability of sinterable (La,Ca)CrO3-δ powder was investigated. The ceramic method (powder mixing method) resulted in inhomogeneous distributions of the calcium content (x) in the perovskite phase (La1-xCaxCrO3-δ) after calcining at a temperature from 1223 to 1373 K. More homogeneous powder was obtained by the liquid mixing m method. The distribution of calcium content caused a large amount of second phases such as calcium oxychromates (Cam(CrO4)n) in a powder prepared by the ceramic method, and an excess amount of the second phase remained as Ca5(CrO4)3OH on the surface of the ceramics after sintering at 1573 K. During a treatment in an H2+H2O gaseous mixture at 1273 K for 627 h, Cam(CrO4)n decomposed to CaO and α-CaCr2O4, and the decomposition was enhanced by the existence of silicon-containing impurities. The liquid mixing method minimized the amount of Cam(CrO4)n, and resulted in sufficient chemical stability in H2+H2O.",

author = "Natsuko Sakai and Tatsuya Kawada and Harumi Yokokawa and Masayuki Dokiya",

year = "1993",

month = nov,

day = "1",

language = "English",

volume = "101",

pages = "1164--1169",

journal = "Journal of the Ceramic Society of Japan. International ed.",

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TY - JOUR

T1 - Effect of preparation method on chemical stability of sinterable calcium doped lanthanum chromites

AU - Sakai, Natsuko

AU - Kawada, Tatsuya

AU - Yokokawa, Harumi

AU - Dokiya, Masayuki

PY - 1993/11/1

Y1 - 1993/11/1

N2 - The effect of preparation method on the chemical stability of sinterable (La,Ca)CrO3-δ powder was investigated. The ceramic method (powder mixing method) resulted in inhomogeneous distributions of the calcium content (x) in the perovskite phase (La1-xCaxCrO3-δ) after calcining at a temperature from 1223 to 1373 K. More homogeneous powder was obtained by the liquid mixing m method. The distribution of calcium content caused a large amount of second phases such as calcium oxychromates (Cam(CrO4)n) in a powder prepared by the ceramic method, and an excess amount of the second phase remained as Ca5(CrO4)3OH on the surface of the ceramics after sintering at 1573 K. During a treatment in an H2+H2O gaseous mixture at 1273 K for 627 h, Cam(CrO4)n decomposed to CaO and α-CaCr2O4, and the decomposition was enhanced by the existence of silicon-containing impurities. The liquid mixing method minimized the amount of Cam(CrO4)n, and resulted in sufficient chemical stability in H2+H2O.

AB - The effect of preparation method on the chemical stability of sinterable (La,Ca)CrO3-δ powder was investigated. The ceramic method (powder mixing method) resulted in inhomogeneous distributions of the calcium content (x) in the perovskite phase (La1-xCaxCrO3-δ) after calcining at a temperature from 1223 to 1373 K. More homogeneous powder was obtained by the liquid mixing m method. The distribution of calcium content caused a large amount of second phases such as calcium oxychromates (Cam(CrO4)n) in a powder prepared by the ceramic method, and an excess amount of the second phase remained as Ca5(CrO4)3OH on the surface of the ceramics after sintering at 1573 K. During a treatment in an H2+H2O gaseous mixture at 1273 K for 627 h, Cam(CrO4)n decomposed to CaO and α-CaCr2O4, and the decomposition was enhanced by the existence of silicon-containing impurities. The liquid mixing method minimized the amount of Cam(CrO4)n, and resulted in sufficient chemical stability in H2+H2O.

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M3 - Article

AN - SCOPUS:0027704209

SN - 0912-9200

VL - 101

SP - 1164

EP - 1169

JO - Journal of the Ceramic Society of Japan. International ed.

JF - Journal of the Ceramic Society of Japan. International ed.

IS - 11

ER -

Effect of preparation method on chemical stability of sinterable calcium doped lanthanum chromites

Abstract

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